• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 703
  • 479
  • 221
  • 137
  • 89
  • 27
  • 22
  • 19
  • 16
  • 14
  • 14
  • 14
  • 14
  • 14
  • 14
  • Tagged with
  • 2039
  • 600
  • 409
  • 229
  • 199
  • 197
  • 141
  • 132
  • 127
  • 117
  • 115
  • 113
  • 108
  • 96
  • 95
  • 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.
61

Trace determination of ammonia and methylamines by flow injection extraction : ion chromatography in estuarine and marine environments

Gibb, Stuart William January 1994 (has links)
No description available.
62

Intrauterine insemination to improve fertility with frozen semen in sheep

Findlater, Richard Cameron Fraser January 1989 (has links)
No description available.
63

Opiod-mediated luteinizing hormone control in ewes : ovarian steroid involvement

Yang, K. P. January 1987 (has links)
No description available.
64

The social context of family planning policy in highland Chiapas, Mexico

Thompson, Mary Summers January 1999 (has links)
This thesis focuses on the concept of informed choice in family planning and how numerical and systematic targeting aimed at raising the numbers of contraceptive acceptors fundamentally undermines this concept in highland Chiapas. The Government of Mexico’s policy aims within its Reproductive Health Programme (1995-2000) are to reduce the total fertility rate whilst promoting reproductive health services and family planning choices. Though Mexico has seen a decline in its total fertility rate attributed to increased contraceptive use in urban areas, in rural parts the rate remains high. Consequently, the rural poor, and in Chiapas overwhelmingly indigenous populations, have become a major target of the Reproductive Health Programme. Monthly targets are set for clinics and family planning services are offered systematically every time a woman attends a clinic for whatever reason. Amongst the factors which must be accounted for in assessing family planning provision in highland Chiapas are cultural differences between mestizo providers and the indigenous target groups as well as local economic and political conditions. Presently, the state of Chiapas is highly militarised and under the cloud of a low intensity war precipitated by the Zapatista uprising in 1994. The provision of any kind of health services is difficult under these situations, but more so what one considers the distrust sown between some indigenous communities and the government Who provide the health services. This thesis examines the practicalities of implementing a global policy at a local level and the constraints faced by both providers and intended recipients in the social context of Los Altos. Mindful of the care required in identification most people in this thesis (with the exception of a few well-known academics) appear under pseudonyms.
65

The potential roles of Albizia zygia in cocoa plantation systems of Ghana

Anim-Kwapong, Gilbert John January 1994 (has links)
No description available.
66

Regulation of ovarian function by the germ cell specific DAZL gene

Brown, Yvonne A. R. January 2009 (has links)
The RNA binding protein DAZL (Deleted in Azoospermia) is essential for germ cell survival and subsequent fertility. The transgenic mouse DAZL model has confirmed that knockout (KO) females are infertile as a direct consequence of complete postnatal oocyte ablation. Interestingly, the heterozygous (Het) DAZL females have increased fertility giving rise to significantly more viable offspring, accompanied by significantly reduced plasma FSH and increased inhibin B compared to levels observed in the wildtype (Wt) females. Recent studies to identify putative DAZL mRNA targets suggest that DAZL may have multiple functions and mRNA targets throughout germ cell development. However, how this protein functions within the oocyte and how functional copy number gives rise to increased fertility remains to be fully elucidated. The studies in this thesis sought to identify putative DAZL mRNA targets in addition to molecular mechanisms which may be either affected direct or indirectly as a result of the functional copy number of DAZL (Wt or Het) within the oocyte or follicular unit. Oocytes from Wt and Het were evaluated for their expression of selected oocyte genes and comparative analysis suggests that oocyte gene expression is significantly altered between the genotypes. Genes of interest include Oosp1 and H1foo, both of which are down-regulated in mRNA expression in Het d21 oocytes and d10 ovaries compared to the Wt. Furthermore, an in silico bioinformatics approach was utilised to identify putative DAZL mRNA targets using a consensus DAZL binding sequence. One candidate target, PDCD4, previously identified as a tumour suppressor gene was selected for further investigation. Despite PDCD4 mRNA and protein being highly expressed within the ovary, no difference in mRNA levels between Het and Wt was observed. However, although not ruling out the possibility of being a DAZL target we now have evidence that PDCD4 can function within the steroidogenic cells of the corpus luteum in relation to functional luteolysis. Indirect actions of DAZL upon local regulation and response of follicle growth in culture were evaluated to investigate follicles at the gonadotrophin dependent stage of growth. Individual follicles from Wt and Het d21 mice were cultured in the presence of FSH at 1iu, 0.5iu, 0.1iu and 0.01iu for a six day period. Final follicle size/morphology did not differ between genotypes at 1iu, 0.5iu and 0.1iu of FSH, but by d3 at 0.01iu FSH growth of Wt follicles was significantly (P<0.001) perturbed compared to the Het. Despite no difference in final size between 1iu, 0.5iu, 0.1iu FSH treatments, mRNA analysis of individual follicles demonstrated a significant up-regulation of FSH receptor (P<0.05), aromatase (P<0.05) and inhibin βA (P<0.01) and a significant down-regulation in inhibin βB (P<0.01) expression in the Het follicles compared to the Wt, suggesting an increase in follicle maturity, sensitivity and hence suitability for selection as viable pre-ovulatory follicles. Furthermore, atresia rates from cultured follicles were significantly lower (P<0.05 (1iu, 0.1iu FSH); P<0.01(0.01iu FSH)) in the Het compared to the Wt. These studies provide strong evidence that multiple mechanisms within the oocyte/follicle are directly and indirectly affected as a result of functional copy number of DAZL. Although direct in vivo targets remain to be identified it is clear that DAZL protein potentially targets multiple mRNAs at different stages of development, pre-programming the oocyte to increase the sensitivity of follicle and/or the functioning within a transcription complex regulating development. In conclusion, the beneficial consequences of increased fertility in the Het females is accompanied by a possible acceleration in oocyte and follicle maturation, an increased sensitivity to FSH in vitro with evidence of advanced stages of growth and, a reduction in follicle atresia. These differences support the suggestion that DAZL is having systemic effects on the paracrine communication within the follicle unit between the oocyte and somatic cells altering regulation and subsequent selection, and affecting final ovulation rate and litter size.
67

The physiology and aetiology of intersexuality in pigs

Chalmers, Charlotte January 1988 (has links)
No description available.
68

Studies of aspects of biogeochemical cycling, with particular reference to soil sustainability and to the sea-salt effect

Elias, Eltijani Abdelrahiem January 1996 (has links)
The concept of soil sustainability has been concisely reviewed, to show the central role of biogeochemical cycling in sustaining fertility of both natural and managed soils. The role of sea salt inputs from the atmosphere within the context of biogeochemical cycling of base cations, concentrating upon the ameliorative effects that base cation inputs from the atmosphere may have against soil acidification in acidification-sensitive upland soils in Scotland, is then discussed more fully. Three approaches were used to try to confirm the importance of the sea salt effect to Scottish upland soils. Studies under controlled laboratory conditions provided strong evidence that maintaining soils under field moist conditions caused considerable increases in exchangeable Ca2+:Na + ratios, which could be attributed to internal soil action redistributions in the absence of a sea salt input. The changes in soil pH over time were not as simple as had been initially expected, partly as a consequence of the complications caused by organic matter oxidation. This study clearly showed it is unwise to store field moist soils in a cooled room for a few weeks prior to analysis. Samples stored for 20 months were re-analysed to look for effects that could be attributed to the elimination of sea salt inputs, but the results did not provide evidence for a sea salt effect. Interpretation was difficult because of the possibility of errors occurring as a result of soil storage in a cold room for up to a few weeks prior to soil analysis, and the high degree of organic matter oxidation. The latter results in release of SO42-, which was removed by precipitation of aluminium sulfate. Repacked soil columns containing individual soil horizons were subjected to simulated high sea salt and low sea salt rainfall treatments over three months. One set of soil horizons was pre-treated to remove organic matter. The results of this experiment were much more unequivocal, with large increases in exchangeable Na+ and Mg2+ concentrations and corresponding soil pH shifts. Finally, it was hypothesised that, if soils with low mineral weathering rates in north east Scotland were susceptible to strong sea salt effects, this should be reflected directly in the associated river water composition. This was confirmed experimentally, and there was a strong link between susceptibility to sea salt effects and susceptibility to acidification.
69

Female education and Fertility Desires in Cameroon

Ekane, Duone January 2016 (has links)
AbstractSocio-economic changes have been identified to alter demographic behaviour, most especially fertility desires. Cameroon just like most Sub Saharan African countries started experiencing decline in its fertility rates not too long ago. A couple of factors have been identified to influence women’s childbearing. Education has been pinpointed as one of the pivotal factors that play a role in influencing female fertility desire. Discussion on education in this paper is made in reference to educational attainment. This research had the aim of examining whether education level attainment (i.e. primary, secondary and university) influences women’s desire to have another child in Cameroon. The target group of the study was women who had at least one child, and their ages ranged from 15 to 45 years. To be able to conduct the study the 2011 demographic health survey (DHS) was used. The demographic theory and demand for children concept were used to provide theoretical framework on the topic. The study was based on the contention that the higher the education level of women, the lesser the desire to have children. From the logistic regression performed, the results portrayed that educational level does influence women’s decision to have another child especially for women with primary and secondary education. Women with no education are more likely to want to have another child than women with education. Women with primary and secondary education are significantly less likely to want another child than those with higher education. This result tends to be fall in line to what was expected. The results showed that although education shapes fertility desires, the number of living children, husband employment and household status tend to play more significant role in women’s desire to have another child in Cameroon. Keywords; fertility, Cameroon, female education, demographic health survey, logistic regression
70

Effect of women's education on fertility in Rwanda: Evidence from the 2000 RDHS

Kavatiri, Rwego Albert 14 November 2006 (has links)
Faculty of Humanities School of Social Sciences 0513951x RWEGAL@yahoo.fr / Most studies indicate that women’s education plays a very important role in driving demographic transition. This study aims at exploring the effect of women’s education on fertility in Rwanda. The study is based on the analysis of the 2000 Rwanda Demographic and Health Survey and employs both direct and indirect methods of estimating fertility. Bongaarts proximate determinants model and such statistical analyses as PATH analysis. The major finding of the study is that although fertility is still high in Rwanda there is some evidence of fertility decline and marriage is the most important proximate determinant of fertility in the country. The study recommends that more studies are needed to find out socioeconomic variables that affect fertility and contribute to low contraceptive use in the country.

Page generated in 0.0481 seconds