全文获取类型
收费全文 | 367篇 |
免费 | 37篇 |
专业分类
404篇 |
出版年
2022年 | 3篇 |
2021年 | 13篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 16篇 |
2012年 | 24篇 |
2011年 | 14篇 |
2010年 | 17篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1992年 | 5篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1959年 | 2篇 |
1957年 | 3篇 |
1948年 | 2篇 |
1947年 | 2篇 |
1935年 | 3篇 |
1933年 | 2篇 |
1909年 | 2篇 |
排序方式: 共有404条查询结果,搜索用时 15 毫秒
1.
Butow Barbara; Wynne David; Sukenik Assaf; Hadas Ora; Tel-Or Elisha 《Journal of plankton research》1998,20(2):355-369
Lipid peroxidation in Peridinium samples taken from two differentdepths in Lake Kinneret fluctuated throughout the spring withan overall increasing trend. Samples from 0.5 and 5 m showeda similar peroxidation pattern, which was maximal after thefall off in algal biomass. The rapid decline in Peridinium biomasscoincided with ambient lake temperatures of 2123C. Fattyacid composition profiles were similar at both depths, althoughafter the peak of the bloom, a significant increase in polyunsaturatedfatty acids and oleic acid was only found at 0.5 m, togetherwith a decrease in the percentage of polyunsaturated fatty acids.These effects were related to ambient light stress rather thana result of lipid peroxidation. Lake samples taken at differentperiods of the bloom and incubated at various temperatures showeddifferential peroxidation. Higher temperatures caused increasedlipid peroxidation, but this appeared to be dependent on thesampling period. Samples withdrawn from the lake at the beginningof the bloom showed little peroxidation after a 5 day incubationat 14C, room temperature (25C) or ambient lake temperature(16C) compared to mid-bloom samples in which there was a significantincrease in peroxidation when they were incubated at room temperature(25C) or ambient lake temperature (22C). Incubation at 14Cinhibited peroxidation; however, samples from mid-bloom againshowed enhanced peroxidation compared with those from the beginningof the bloom. These in situ results suggested a relationshipbetween temperature, another environmental variable during thebloom and lipid peroxidation in Peridinium. As total dissolvedinorganic carbon (DIC) concentrations fall significantly duringthe progress of the bloom and represent an important sourceof environmental stress, laboratory experiments were establishedto investigate the synergistic effect of temperature and carbonnutrition on lipid peroxidation in Peridinium cultures. Increasedtemperature alone caused a slight increase in lipid peroxidation,but this was greatly augmented by carbon limitation. Althoughcarbon limitation induced increased catalase activity, at highertemperatures activity declined after 48 h, allowing for thesubstantial increase in lipid peroxidation. 相似文献
2.
R. Day J. A. Nielsen A. Korten G. Ernberg K. C. Dube J. Gebhart A. Jablensky C. Leon A. Marsella M. Olatawura N. Sartorius E. Strömgren R. Takahashi N. Wig L. C. Wynne 《Culture, medicine and psychiatry》1987,11(2):123-205
This study reports on the findings from a WHO sponsored cross-national investigation of life events and schizophrenia. Data are presented from a series of 386 acutely ill schizophrenic patients selected from nine field research centers located in developing and developed countries (Aarhus, Denmark; Agra, India; Cali, Colombia; Chandigarh, India; Honolulu, USA; Ibadan, Nigeria; Nagasaki, Japan; Prague, Czechoslovakia; Rochester, USA). On a methodological level, the study demonstrates that life event methodologies originating in the developed countries can be adapted for international studies and may be used to collect reasonably reliable and comparable cross-cultural data on psychosocial factors affecting the course of schizophrenic disorders. Substantive findings replicate the results of prior studies which conclude that socioenvironmental stressors may precipitate schizophrenic attacks and such events tend to cluster in the two to three week period immediately preceding illness onset.The paper was prepared by these authors on behalf of the collaborating investigators listed on page 196. 相似文献
3.
4.
Effect of microspore stage and media on anther culture of peanut (Arachis hypogaea L.) 总被引:2,自引:0,他引:2
Martha C. Willcox Sandra M. Reed Joyce A. Burns J. C. Wynne 《Plant Cell, Tissue and Organ Culture》1991,24(1):25-28
This study was designed to study the effects of stage of microspore development and culture medium on androgenic response in peanut (Arachis hypogaea L.). Anthers of various developmental stages were cultured for 7 days, then fixed and observed cytologically. Three sets of media, involving different basal media, growth regulators, sucrose levels and glutamine concentrations, were tested. In all experiments, the stage of development of the microspores at the time of culture was highly significant. The early uninucleate microspores stage was identified as producing the highest anther response rating. The effect of media was nonsignificant in all experiments. However, the stepwise modification of the media through the course of the study resulted in an almost 8 x increase in anther response rating. Numerically, the best media tested was N6 basal medium with 1 mg 1-1 NAA, 0.1 mg 1-1 BA, 5.5% sucrose, and 3.5 g 1-1 glutamine. While no haploids were obtained, four-nucleate cells were observed, indicating the potential in peanuts for an androgenic reponse. 相似文献
5.
Nitrate reductase: an improved assay method for phytoplankton 总被引:1,自引:0,他引:1
Hochman Ayala; Nissany Aliza; Wynne David; Kaplan Bina; Berman Thomas 《Journal of plankton research》1986,8(2):385-392
A new assay for measuring the activity of nitrate reductasein phytoplankton, based upon the permeability of cells treatedwith toluene to substrates and products, is described. The methodis simple and, since the reaction is carried out directly ona glass fiber filter, can be easily performed in the field oron shipboard. In comparison with previous methods, this techniquegave higher absolute amounts of NO2 formed per unit tuneand higher enzymatic activities per sample volume when testedwith axenic algal cultures and with natural phytoplankton populationsfrom Lake Kinneret, the River Jordan and the Eastern Mediterranean. 相似文献
6.
7.
8.
G. Wynne Griffith A. M. Adelstein P. M. Lambert J. A. C. Weatherall 《BMJ (Clinical research ed.)》1972,3(5826):553-556
Early neonatal mortality in England and Wales in the second quarter of 1970 after a major influenza epidemic was slightly but significantly higher than in the corresponding quarter of the previous year. An increase was also noted in the first quarter of 1970. Analysis of infant mortality and an index of influenza prevalence over the past quarter-century indicates that similar increases occurred in relation to four of the other five major influenza epidemics during the period, the exception being the “Asian ''flu” epidemic of the autumn of 1957. It is suggested that the increased mortality in 1970 was the consequence of an increase in the prematurity rate, but we have no evidence to indicate whether the effect is specifically due to the virus or is nonspecific in nature. 相似文献
9.
The effect of manipulating cereal aphid population development, by either adding aphids or spraying with an aphid-specific insecticide, on the predatory mite fauna was investigated. Populations of the anystid mite, Anystis baccarum (L.) were very small until late June when numbers built up rapidly at the time of the aphid population decline. There was however, no significant relationship between aphids and numbers of mites over the whole season. Preliminary electrophoretic analysis of two enzymes in the gut of anystid mites indicated that they may have been feeding on thrips, Limothrips cerealium Haliday. The free-living soil Mesostigmata had two population peaks, each related, the first positively and the second negatively to aphid populations. 相似文献
10.
Christian Boedeker Michael J. Wynne Giuseppe C. Zuccarello 《Journal of phycology》2023,59(6):1284-1298
The continental coasts and remote islands in the high-latitude Southern Hemisphere, including the subantarctic region, are characterized by many endemic species, high abundance of taxa, and intermediate levels of biodiversity. The macroalgal flora of these locations has received relatively little attention. Filamentous green algae are prolific in the intertidal of southern islands, but the taxonomy, distribution, and evolutionary history of these taxa are yet to be fully explored, mostly due to the difficulty of access to some of these locations. In this study, we examined specimens of the order Cladophorales from various locations in the high-latitude Southern Hemisphere including the subantarctic (the Auckland Islands, Bounty Islands, Campbell Island, Macquarie Island, and Kerguelen Islands), as well as mainland New Zealand, the Chatham Islands, Chile, and Tasmania. The analyses of the rDNA sequences of the samples revealed the existence of two new clades in a phylogeny of the Cladophoraceae. One of these clades is described as the novel genus Vandenhoekia gen. nov., which contains three species that are branched or unbranched. The amended genus Rama is reinstated to accommodate the other clade, and contains four species, including the Northern Hemisphere “Cladophora rupestris.” In Rama both branched and unbranched morphologies are found. It is remarkable that gross morphology is not a predictor for generic affiliations in these algae. This study illustrates that much can still be learned about diversity in the Cladophorales and highlights the importance of new collections, especially in novel locations. 相似文献