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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
421

Soil fertility studies with peanuts

Strauss, John L. January 1949 (has links)
M.S.
422

Molecular phenotypes associated with heifer fertility

Marrella, Mackenzie Ann 16 May 2024 (has links)
Doctor of Philosophy / Before the early 2000s, many producers were heavily selecting for production traits without accounting for the negative relationship between many production traits and fertility. The large decrease in fertility that occurred as a result of these selection practices put a heavy burden on producers. Replacement heifer development is the third largest cost incurred by producers, behind feed and labor. Consequently, the failure of a heifer to conceive in her first breeding season translates directly into financial loss for the producer and lasting consequences on the animal's longevity and performance in subsequent breeding seasons. To make improvements in a trait, or traits, of interest, producers often selectively breed two animals with desirable characteristics. However, the complex nature of fertility traits limits the effectiveness of this method. As a result, researchers have been attempting to identify biological molecules whose abundance differs between cattle of differing fertility potential, termed molecular markers, that could be used to identify superior cattle earlier and more accurately. While a good amount of research has been conducted in mature cows and in a laboratory setting, very few studies have attempted to identify molecular markers of fertility in heifers. Therefore, the objective of this work was to identify different biological molecules (genomic variants, genes, proteins, and metabolites) whose abundance differed between heifers with varying fertility potential. Investigation into DNA variations led to the identification of three variants that were associated with fertility, 16 variants that were associated with health, and 29 variants that were associated with both health and fertility. Given that some variants can impact a trait by changing gene expression, we attempted to identify variations in RNA that were having this effect on heifer fertility. Although some variants were found to influence gene expression, we were unable to correlate these changes with fertility differences. However, in a different study, we were able to identify two genes (APMAP and DNAI7), as well as one protein (alpha-ketoglutarate-dependent-dioxygenase FTO), that differed significantly between fertile and sub-fertile heifers. Importantly, the results of this study allowed us to create a biological profile that was capable of accurately distinguishing 21/22 heifers based on their fertility potential. Finally, investigation of the metabolite profile revealed one metabolite (2-dehydro-D-gluconate) that was differentially abundant between fertile and sub-fertile heifers. Overall, this work sheds light on the complex nature of heifer fertility and provides several potential molecular that could be used to distinguish between heifers of varying reproductive potential.
423

Fertility awareness-based methods of avoiding and achieving pregnancy : an effective means of family planning and promoting women's empowerment

Woodman, Maureen R. 01 January 2010 (has links)
Fertility awareness-based methods or natural family planning methods are an effective means of family planning that is seldom recommended by the medical community. After a review of literature it is concluded that such methods empower women and couples, that there is a need for a referral system and natural family planning clinics, and a need for a standardized fertility consultant license. Furthermore, such methods have been highly effective family planning tools in third world countries with limited access to contraceptives. Research on provider attitudes is scarce and further study is required, considering some women cannot or will not utilize mechanical or barrier methods of contraception.
424

Accumulation and recovery of nitrogen in mixed farming systems using legumes and other fertility building crops

Doel, J. M. January 2012 (has links)
Fertility-building crops (FBCs) offer the opportunity to alleviate the costs of inorganic fertiliser by providing an alternative supply of available nitrogen (N) in soils. A survey of relevant literature reviewed the types of FBCs, their nitrogen accumulation potentials, residue characteristics, and subsequent release patterns. It also identified a paucity of data concerning the response of different species to UK climatic, soil, and management conditions. In order to investigate these relationships further pot and field trials were established in 2007 at the Royal Agricultural College, Cirencester (SP 00481 01382) and at Coates Manor Farm (SO 98473 00402) on Sherborne series (typical Cotswold) soils, to investigate the biology and morphology of FBCs potentially suitable for short term fertility-building, their accumulation of N under field conditions, and its subsequent recovery within test crops. Data so obtained was used as a verification and refinement tool for the FBC model (Cuttle et al, 2003), a simple, commercially applicable, rotation-based model which can be applied to both organic and conventional production systems. Nine leguminous and two non-leguminous FBC treatments were established in April 2007 by straight sowing, followed by mulching at the conclusion of the nitrogen accumulation phase and by undersowing in spring barley (Hordeum sativum). The recovery test crops (winter and spring wheat Triticum aestivum L.) were established in September 2007 and March 2008. All FBCs established successfully. Above-ground dry matter (DM) yield and residue quality (C:N ratio) of FBCs varied significantly (P<0.05) between crops and cropping regimes with a significant correlation (r2=0.418) between DM yields and C:N ratios. FBCs and cropping regimes had significant effects (P<0.001 and P<0.05 respectively) on potential mineralisable nitrogen (PMN) levels in the soil and on the grain yields of winter and spring wheat test crops. Straight sown Lupinus albus, Trifolium pratense, Trifolium repens and a legume mixture resulted in higher winter wheat grain yields. However, the opportunity cost associated with straight sowing (i.e. the gross margin foregone from a spring barley crop) meant that the rotation would probably not be viable economically. Undersown Medicago lupulina, Vicia villosa, T. pratense, T. repens and the legume mixture gave worthwhile yield increases in spring wheat without incurring a yield penalty in the spring barley cover crop. Following enhancement and using actual data from the trials, the FBC model (Cuttle et al, 2003) provided encouraging predictions (R>0.6) for soil mineral nitrogen (SMN) and key parameters were identified for future use. It was concluded that FBCs established for short term soil fertility building could provide a worthwhile enhancement of soil N levels and grain yields in a conventional arable rotation, particularly in spring wheat following FBCs undersown in spring barley. It was also concluded that the FBC model (Cuttle et al, 2003), following further enhancement, and using additional data from these and other similar trials, could provide reasonably accurate estimates of SMN to aid more precise applications of N fertiliser in the future.
425

Endocrine function and fertility preservation in women surviving cancer : a study on cancer treatment and fertility

Botha, Matthys Hendrik 12 1900 (has links)
Thesis (DMed (Obstetrics and Gynaecology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Chapter 1 is a literature review investigating the incidence of cancer in children and young adults. It describes the most important treatment options including chemotherapy, radiotherapy and surgery and the effect of treatment on future endocrine development and fertility. Different primary cancer sites are discussed in more detail. Chapter 2 is a literature review on the effects of cancer surgery in women and the options for fertility sparing. Cervical cancer and pre-cancer are discussed in detail with options for more conservative surgery in selected patients. A summary of the available published cases of trachelectomy with pregnancy outcomes is included. Other gynaecological cancers requiring surgery are also discussed with reference to conservative options. Chapter 3 is a literature review about the medical (pharmacological) options for protection of ovarian function in patients undergoing oncotherapy. The role of gonadotrophin releasing hormone analogues and hormonal contraceptives in ovarian suppression is discussed in detail. Chapter 4 This chapter examines germ cell physiology with reference to cryopreservation. It includes two major parts. Part 1 is the description of germ cell- and follicle physiology, the principles of cryobiology followed by a review of oocyte cryopreservation and ovarian tissue preservation. Both slow freezing and vitrification techniques are described. The second part of chapter 4 is a report on a randomised controlled evaluation of two different slow freezing cryopreservation protocols. This experimental study compared ultrastructural changes in fresh and previously cryopreserved ovarian cortical tissue after equilibration and thawing using two different cryoprotectants. This is the first randomised investigation into DMSO and PROH as cryoprotectants. Chapter 5 is an investigation into cryopreservation of ovarian tissue as a strategy to protect hormonal function and fertility against gonadotoxic treatment. This chapter consists of two parts. The first part is a thorough literature review of all the published work about grafting of previously cryopreserved ovarian tissue. The largest case series found from a single institution was five patients. Another report of six patients included patients from various sites in Denmark. Part 2 is a description of a cohort of patients followed up after re-implantation of previously cryopreserved ovarian cortical tissue. Follow-up hormone levels of 13 individual cases are described in detail. This is the largest case series ever reported. The experimental study described in Chapter 4 and the clinical study described in Chapter 5 was approved by the ethical research committee of the Faculty of Health Sciences, Stellenbosch University, project number N05/10/182. Chapter 6 provides an integrated overview of the incidence and treatment of cancer in young women and how its negative effects may be prevented or mitigated. Aspects of chemotherapy, radiotherapy and surgery are evaluated where it may affect future reproductive health. The role of oocyte and ovarian tissue cryopreservation is discussed. Guidelines are provided for clinicians. / AFRIKAANSE OPSOMMING: Hoofstuk 1 Hierdie is ‘n literatuuroorsig wat die insidensie van kanker in kinders en jong volwassenes ondersoek. Dit sluit die mees belangrike behandelingsopsies in, naamlik chemoterapie, radioterapie en chirurgie en die effek wat behandeling mag hê op toekomstige endokriene ontwikkeling en fertiliteit. ‘n Verskeidenheid kanker tipes word in meer detail beskryf. Hoofstuk 2 Hoofstuk 2 is ‘n literatuuroorsig oor die effekte van kankerchirurgie in vroue en die geleenthede tot beskerming van fertiliteit. Servikale kanker en voorlopers van servikale kanker word bespreek en die opsies vir konserwatiewe chirurgie in uitgesoekte pasiënte word gegee. ‘n Opsomming van die inligting wat beskikbaar is oor tragelektomie en swangerskap uitkomste word ingesluit. Ander ginekologiese kankers wat chirurgie mag benodig, word ook bespreek met verwysing na konserwatiewe hantering. Hoofstuk 3 ‘n Literatuuroorsig oor die mediese (farmakologiese) opsies vir die beskerming van ovariële funksie in pasiënte wat behandeling ontvang vir kanker. Die rol van gonadotropien-vrystellingshormoon-analoë en hormonale kontrasepsie vir ovariële onderdrukking word in detail bespreek. Hoofstuk 4 Hierdie hoofstuk ondersoek kiemselfisiologie met verwysing na vriesbewaring. Dit is verdeel in twee dele. Deel 1 is ‘n beskrywing van kiemsel- en follikelfisiologie en die beginsels van vriesbiologie. Dit word gevolg deur ‘n oorsig van oösiet vriesbewaring en ovariële weefselbewaring. Stadige bevriesing en vitrifikasie- metodes word bespreek. Die tweede deel van hoofstuk 4 is ‘n verslag oor ‘n gerandomiseerde, gekontroleerde evaluasie van twee stadige bevriesingsmetodes. Hierdie eksperimentele studie het die ultrastrukturele veranderinge vergelyk in vars en voorheen bevrore ovariële kortikale weefsel na ekwilibrasie en ontdooiing met twee verskillende vriesbeskermers. Dit is die eerste gerandomiseerde studie oor DMSO en PROH as vriesbeskermers. Hoofstuk 5 Hierdie hoofstuk handel oor ‘n ondersoek na vriesbewaring van ovariële weefsel as ‘n benadering tot beskerming van hormonale funksie en fertiliteit teen gonadotoksiese behandeling. Die hoofstuk bestaan uit twee dele. Die eerste deel is ‘n deeglike oorsig van die literatuur oor al die beskikbare werk wat handel oor terugplasing van voorheen bevrore ovariële weefsel. Die grootste pasiëntreeks van ‘n enkel instelling was slegs vyf pasiënte. ‘n Ander beskrywing van ses pasiënte het pasiënte van verskeie eenhede in Denemarke ingesluit. Deel 2 is ‘n beskrywing van ‘n groep pasiënte wat opgevolg is na oorplanting van voorheen bevrore ovariële kortikale weefsel. Opvolg hormoonvlakke van 13 gevalle word in detail bespreek. Hierdie is die grootste pasiëntreeks wat tot nog toe beskryf is. Die eksperimentele studie wat in hoofstuk 4 beskryf word en die kliniese studie wat in hoofstuk 5 beskryf word, is goedgekeur deur die etiese navorsingskomitee van die Fakulteit Gesondheidswetenskappe van die Universiteit Stellenbosch met die projeknommer N05/10/182 Hoofstuk 6 Hierdie is ‘n geïntegreerde oorsig van die voorkoms en behandeling van kanker in jong vroue en hoe die negatiewe effekte daarvan voorkom of verminder kan word. Aspekte van chemoterapie, radioterapie en chirurgie word geëvalueer ten opsigte van die effek op toekomstige reproduktiewe gesondheid. Die rol van oösiet- en ovariële weefselvriesbewaring word bespreek. Riglyne vir klinici word gegee.
426

EFFECTS OF ELEVATING BLOOD LIPIDS IN ENERGY DEFICIENT ANESTROUS DAIRY HEIFERS ON PITUITARY RESPONSE TO GONADOTROPIN RELEASING HORMONE CHALLENGE.

Johnson, Mark Steven, 1955- January 1985 (has links)
No description available.
427

台灣生育政策之研究 / The Study of Fertility Policy in Taiwan

易雅如, Yi, Ya Ju Unknown Date (has links)
這篇論文的目的在理論的探討及生育政策的轉變的基礎之下,了解文化、社會、經濟和生育之間的關係、台灣政府在生育方面的政策所扮演的角色及這些政策對台灣人口所造成的影響。由法國、德國、英國、美國及日本的經驗,我們可以知道生育政策在人口變遷扮演了一個非重要的角色,而這些成功或失敗的政策可成為政府將來制定相關政策時的參考。 / The purpose of this master thesis “The Study of Fertility Policy in Taiwan” is to examine the relation between culture, society, economy and fertility based upon theories and to introduce the transition of fertility policy, the role of the Taiwan government in influencing and regulating childbearing and assess the demographic impacts of population. Based on the experience of France, Germany, United Kingdom, United States and Japan, fertility policies play an important role in demographic transition and may provide a window into Taiwan’s future development. This study finds that low fertility is a widespread phenomenon in Taiwan and is expected to continue in the foreseeable future. Government policies, as in the cases of France and The United States, are effective in combating low fertility. France is a pioneer in providing financial rewards and services to families and children while minorities and immigration have contributed to increased fertility rates in United States. Without national subsidies and affordable childcare, Taiwan’s fertility policies have failed to maintain a replacement rate since 1983. Judging from policies and practices in advanced countries, Taiwan’s governments should foster a supportive working environment for women and families when they are having or raising children. Specifically, whether Taiwan’s birth rate can be pushed up will depend on measures that offer flexible work schedules, better subsidies for maternity leave, and affordable, high-quality day-care services for career women. Meanwhile, the government should also modulate the education system and redistribute education resources, re-evaluate the relationship between population and sustainable development, better utilize the ageing labor force and strengthen lifelong-learning for older workers.
428

Vliv rozpadu manželských svazků na plodnost v České republice / Impact of Marital Dissolution on Fertility in the Czech Republic

Filasová, Alena January 2013 (has links)
Impact of Marital Dissolution on Fertility in the Czech Republic Abstract The intention of this study is to analyze fertility of people who experience a divorce or husband/wife death in their reproductive age so it could be find out if these people have more or less children than people whose marriage persists until the age of 50. The conclusions are made based on the study of data from the second wave of Generations and Gender Survey which took place in the Czech Republic in 2008. The life table method (its output Survival Distribution Function) and Cox regression model are used for the analysis. Reproductive behavior of people who never enter into marriage, those who spend their reproductive age in the first marriage and those who experience the first marital dissolution before their 50th birthday is compared. The analysis of divorced and widowed people fertility is supplemented by evaluation of an effect that certain variables like age, number of children and age of the youngest child in the year of the first marital dissolution have on the follow-up reproductive behavior of these men and women. The situation about the partnership after the dissolution of the first marriage was identified as the most significant. People who find a new partner after their first marital dissolution have on average more...
429

An economic analysis of fertility in Hong Kong.

January 1985 (has links)
by Wong Yiu Kwong. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985 / Bibliography: leaves 52-54
430

Characteristics of Australian edible fungi in the genus Lepista and investigation into factors affecting cultivation

Stott, Karen Gai, University of Western Sydney, Hawkesbury, Faculty of Science and Technology, School of Science, Food and Horticulture January 1998 (has links)
This thesis focuses on the edible fungus Lepista (Pied Bleu or Wood Blewit). Factors affecting its potential commercial cultivation were explored and a contribution to knowledge of the morphology and cultivation of Australian species of Lepista has been made. Australian collections of Lepista were made within a 200 km zone of Sydney. A study of the morphology and taxonomic species of these collections was undertaken. Intra- and inter-fertility crosses were completed with French L. nuda and L. sordida to determine genetic relationships and biological species. Suitable substrates for agar medium, spawn production and cultivation were explored. The response to temperature of French and Australian Lepista in vitro, and Australian Lepista under cultivation, using cold shock, was observed. The effect of modified atmosphere exchanges per hour, CO2 levels, and cold shock during the cultivation cycle and sporophore production were investigated. A genebank of Australian Lepista was established. Three species of Lepista were found in Australia : L. nuda, L. sordida and L. saeva. Two other groups of Lepista were identified. The use of A. bisporus compost appeared to be optimal for experimental and commercial applications. Australian isolates of Lepista tolerate higher temperatures than French isolates, and grew at double the rate of the French at all temperatures except 5 degrees centigrade. The length of the spawn run was reduced from 43-58 days to 12-16 days with introduced CO2 of 9,000-11,000 ppm, but an erratic cyclic pattern of net CO2 production occurred which could only be stabilised by increasing ventilation. This initial cyclic pattern appeared to inhibit subsequent sporophore formation. / Doctor of Philosophy (PhD)

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