• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 234
  • 212
  • 20
  • 20
  • 14
  • 12
  • 9
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 6
  • 5
  • Tagged with
  • 641
  • 175
  • 132
  • 72
  • 71
  • 60
  • 56
  • 51
  • 51
  • 51
  • 50
  • 49
  • 46
  • 43
  • 35
  • 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.
141

Distribution of Living Benthic Foraminifera and Its Relationship with the Pigment Concentration in the Sediments from Coastal Region off Southwestern Taiwan

Chen, Li-Ying 15 August 2012 (has links)
The surface sediments off Southwestern Taiwan were collected during three different cruises in May 2009, November 2009, and March 2010, respectively. The concentrations of chlorophyll-a and phaeopigment, as well as benthic foraminifera species, were analyzed. The results show that the concentration of chlorophyll-a decreases with the distance from the shore, and the concentration of chlorophyll-a also decreases with increasing water depth. The concentration of phaeopigment seems to have no significant relationship with the water depth. The relationships between the concentrations of benthic foraminifera, chlorophyll-a, and phaeopigment are also not significant. Because samples were collected from different water depths on the continental shelf, slope and in a canyon, the oceangraphic setting therefore may be one of the main factors which influences the distribution pattern of benthic foraminifera. According to the EOF analysis, the water depth in sampling sites plays a very important role in terms of the distribution of living benthic foraminifera in this study. The distribution do not show significant difference between collecting seasons. Finally, the concentrations of the chlorophyll-a and phaeopigment decrease drastically in a downcore record. Quinqueloculina spp., an epifaunal foraminifer, shows a significant peak concentration in the depth of 5-6 cm downcore. Bioturbation probably was responsible for this change.
142

Investigations into the seasonal deep chlorophyll maximum in the western North Atlantic, and its possible significande to regional food chain relationships /

Ortner, Peter B. January 1978 (has links)
Thesis (Ph. D.)--Massacnusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977. / Includes bibliographical references (leaves 201-220).
143

The near-bottom chlorophyll A̲ maximum in Onslow Bay : effects of wave events on benthic microalgae resuspension /

Manes, Gianluca. January 2003 (has links) (PDF)
Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : 41-46).
144

Temporal and Spatial Distribution of Chlorophyll on the West Florida Shelf

Ault, Danylle N. 05 April 2006 (has links)
The West Florida Shelf (WFS), typically characterized as being oligotrophic, is one of the most productive continental shelves in the United States. In addition to supporting a large fishing industry, the WFS also supports high biomass blooms of the toxic dinoflagellate Karenia brevis. Because of the large ecological and economic impacts these blooms have on the area, the ECOHAB: Florida program was developed to gain a better understanding of red tides and their initiation, maintenance, and dispersal. This interdisciplinary program consisted of monthly cruises from June 1998 through December 2001, with a hiatus from January through March of 2001. Hydrography, nutrients, chlorophyll a, phaeopigments, and a wide variety of other factors were measured during the cruises. In this paper chlorophyll a and phaeopigment concentration, nutrients, and hydrographic data were examined to explain the temporal and spatial distribution of chlorophyll on the shelf. Average surface chlorophyll values were 0.55 mg/m 3 with near bottom values averaging 0.85 mg/m 3. Chlorophyll was found to be highest near the estuaries of Tampa Bay and Charlotte Harbor with a decreasing gradient seaward. Near bottom chlorophyll values were generally two to fourfold greater than surface values. Midshelf stations (35- 50 m) were characterized by high near bottom chlorophyll, whereas the offshore stations (86-200 m) were characterized by a subsurface chlorophyll maximum ranging between 40 to 80 m deep. Nutrients were generally low across the shelf except for 1998 when a subsurface intrusion of nutrient rich slope water reached to the 20 m isobath. Temperatures ranged from 14.00 ° C to 31.47° C. Salinity ranged from 30.5 to 37.50 in the study area. Four blooms of Karenia brevis, lasting several months, contributed to the high chlorophyll concentrations along the inner shelf. Maximum chlorophyll concentrations of 27.10 mg/m 3 were a result of the October 1999 to March 2000 red tide. Blooms of Trichodesmium and diatoms also were contributors to patterns seen on the shelf. Maximum chlorophyll values were generally highest in the late summer and fall except for offshore values which showed little to no seasonality. Inshore of the 50 m isobath, average phaeopigments comprised from 43 to 68 percent of the measured Chl a, while offshore values were from 68 to over 100 percent. Inshore chlorophyll distributions were attributed to riverine and estuarine flux of nutrients, localized upwelling, and recycling of nutrients aided by salinity and temperature fronts. Midshelf distributions were attributed to the movement of biologically important material through the bottom Ekman layer from offshore to the inshore regions of the shelf. Offshore distributions were attributed to Loop Current upwelling and synoptic scale processes associated with seasonal meteorological forcing.
145

Biocatalysis of tyrosinase in chloroform medium using selected phenolic substrates

Tse, Mara. January 1996 (has links)
The biocatalytic activity of mushroom tyrosinase was optimized in chloroform medium, using five selected phenolic substrates, including catechin (CT), vanillin (VA), chlorogenic acid (CA), p-aminophenol (pAP) and hydroquinone (HQ). The specific activity (SA) of tyrosinase determined as the change in absorbance at the selected wavelength per $ mu$g protein per sec ($ delta$A/$ mu$g protein/sec) in chloroform was much higher than that obtained in aqueous media. The optimal amount of enzymatic protein for tyrosinase biocatalysis in chloroform was found to be 44.0 mg protein/L for CT and VA, 31.6, 180.5 and 90.3 mg protein/L, respectively, for CA, pAP and HQ. The optimal pH for the oxidative activity of tyrosinase in chloroform was 6.0 for all the substrates; however, the optimal temperature for enzymatic activity was 30$ sp circ$C for CT and 25$ sp circ$C for the other four substrates. The use of 1.25 and 6.65 mM catechol in chloroform medium activated the tyrosinase activity maximally by 56.2% and 267.2%, respectively for CT and CA as substrates; however, no effect from catechol (0 to 7 mM) was found with VA, pAP or HQ. In addition, the use of 4.25, 2.25 and 5.39 mM ethylenediamine tetraacetic acid (EDTA) in chloroform, with CT, VA and pAP as substrates, inhibited the tyrosinase activity maximally by 44.3, 84.7 and 67.0%, respectively; however, the use of 4.75 and 1.60 mM EDTA activated the enzyme by 101.9% and 115.9%, respectively, for CA and HQ. The use of high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) demonstrated the phenolic substrate bioconversion, whereas the spectrophotometric scanning showed the product formation during the enzymatic reaction. (Abstract shortened by UMI.)
146

Chlorophyll fluorescence as a measure of cold hardiness and freezing stress in 1 + 1 Douglas-fir seedlings : response to seasonal changes in the nursery /

Fisker, Susan E. January 1992 (has links)
Thesis (M.S.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 37-42). Also available on the World Wide Web.
147

Genetic analysis of chlorophyll deficiency in Melilotus alba x M. dentata hybrids with some observations on meitotic irregularities

Bringhurst, Royce S., January 1950 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 89-90).
148

Bakteriochlorophyllvorstufen und Pigment-Protein-Komplexe in Rhodospirillum rubrum ST3 und GN11

Hammel, Jörg U. January 2006 (has links)
Stuttgart, Univ., Diplomarbeit, 2006.
149

Applications of chlorophyll a fluorescence in bio-optical models of phytoplankton biomass and productivity / by Mary Evans Culver.

Culver, Mary Evans, January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references.
150

Bildgebende Spektroskopie an Pflanzenblättern

Smolyar, Nadiya. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2003--Heidelberg.

Page generated in 0.0568 seconds