全文获取类型
收费全文 | 236篇 |
免费 | 28篇 |
专业分类
264篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 22篇 |
2012年 | 16篇 |
2011年 | 26篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有264条查询结果,搜索用时 15 毫秒
1.
This work demonstrates that in vitro sciatic nerves of normal and trembler adult mice can use ketone bodies (beta-hydroxybutyrate and acetoacetate) and butyrate for lipid synthesis. In normal sciatic nerves, beta-hydroxybutyrate is incorporated in total lipids to a larger extent than acetoacetate (141% and 33%, respectively, of acetate incorporation), whereas for trembler sciatic nerves, these percentages are only 69% and 27%. Incorporation of ketone bodies is greater into sterols than into other lipids. Lipid metabolism of ketone bodies in trembler nerves is altered and could reflect a process similar to Wallerian degeneration: a dramatic decrease of sterol and free fatty acid synthesis and an increased synthesis of triglycerides. Moreover, differences seen in precursor incorporation into lipids between normal and trembler sciatic nerves suggest that their lipid metabolism is not the same. 相似文献
2.
Field trials were conducted in Rheola Forest, Wales, Great Britain, to determine the effectiveness of Steinernema feltiae UK strain in controlling the web-spinning larch sawfly Cephalcia lariciphila. Foliar sprays at the rate of 5,000-20,000 nematodes/100 cm branch resulted in 3.4-29.4% infection of sawfly larvae. Soil application of 200 nematodes/cm² resulted in 61% infection of sawfly prepupae and 17.3% of pupae. Prepupal infection ranged from 4.8 to 14.7% 1 year after nematode application. Soil applications of this nematode show that it has potential for biological control of sawfly prepupae. 相似文献
3.
Summary Preincubation at 42o, before infection at permissive temperature by phage , of an Escherichia coli dnaB mutant, provokes a significant increase in survival and mutagenesis of ultraviolet irradiated phage as well as mutagenesis of untreated phage. Similarly to UV irradiation and many chemical mutagens, the inhibition of DNA synthesis by temperature shift of this dnaB mutant induces SOS repair. This work shows that replication blockage in bacterial DNA is not only mutagenic for bacterial DNA itself (Witkin, 1975) but also for normally replicating DNA, probably due to induction of diffusible products. 相似文献
4.
Cryptococcus neoformans cell and culture supernatant extracts were fractionated by ion exchange and gel filtration column chromatography. Various fractions were used to immunize mice, and to assess the release of migration inhibition factor, delayed type hypersensitivity, and protective immunity after challenge with C. neoformans. Results suggest that the C. neoformans fractions, which protect mice, contain a high molecular weight, predominantly carbohydrate antigen that can be distinguished from the capsular polysaccharide. 相似文献
5.
Perrine Pelosse Christopher M. Kribs-Zaleta Marine Ginoux Jorge E. Rabinovich Sébastien Gourbière Frédéric Menu 《PloS one》2013,8(8)
Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments. We developed a simplified multi-stage vector-borne SI epidemiological model to investigate how vector risk-spreading strategies and environmental stochasticity influence the prevalence and evolution of a parasite. This model is based on available knowledge on triatomine biodemography, but its conceptual outcomes apply, to a certain extent, to other vector-borne diseases. Model comparisons between deterministic and stochastic settings led to the conclusion that environmental stochasticity, vector risk-spreading strategies (in particular an increase in the length and variability of development time) and their interaction have drastic consequences on vector population dynamics, disease prevalence, and the relative short-term evolution of parasite virulence. Our work shows that stochastic environments and associated risk-spreading strategies can increase the prevalence of vector-borne diseases and favor the invasion of more virulent parasite strains on relatively short evolutionary timescales. This study raises new questions and challenges in a context of increasingly unpredictable environmental variations as a result of global climate change and human interventions such as habitat destruction or vector control. 相似文献
6.
Ajay Kumar Mishra Perrine Hugon Jean-Christophe Lagier Thi-Tien Nguyen Carine Couderc Didier Raoult Pierre-Edouard Fournier 《Standards in genomic sciences》2013,8(2):290-305
Enorma massiliensis strain phIT is the type strain of E. massiliensis gen. nov., sp. nov., the type species of a new genus within the family Coriobacteriaceae, Enorma gen. nov. This strain, whose genome is described here, was isolated from the fecal flora of a 26-year-old woman suffering from morbid obesity. E. massiliensis strain phIT is a Gram-positive, obligately anaerobic bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,280,571 bp long genome (1 chromosome but no plasmid) exhibits a G+C content of 62.0% and contains 1,901 protein-coding and 51 RNA genes, including 3 rRNA genes. 相似文献
7.
Perrine Hugon Dhamodharan Ramasamy Catherine Robert Carine Couderc Didier Raoult Pierre-Edouard Fournier 《Standards in genomic sciences》2013,8(3):500-515
Kallipyga massiliensis strain ph2T is the type strain of Kallipyga massiliensis gen. nov., sp. nov., the type species of the new genus Kallipyga within the family Clostridiales Incertae Sedis XI. This strain, whose genome is described here, was isolated from the fecal flora of a 26-year-old woman suffering from morbid obesity. K. massiliensis is an obligate anaerobic coccus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 1,770,679 bp long genome (1 chromosome but no plasmid) contains 1,575 protein-coding and 50 RNA genes, including 4 rRNA genes. 相似文献
8.
Mate limitation in populations of the endangered Convolvulus lineatus L.: A case for genetic rescue?
Regina Berjano Perrine Gauthier Alessandro Fisogni David Doblas Virginie Pons John D. Thompson 《Journal for Nature Conservation》2013,21(5):334-341
In self-incompatible clonal plants, the spread of individual plants can exacerbate mate limitation to the point that it becomes a serious constraint on long-term population persistence, especially in small, isolated populations. In such species, it may be necessary to introduce new genetic material from other populations to restore seed production, a strategy termed “genetic rescue”. In this study we assess the potential pertinence of such genetic rescue in the clonal perennial plant Convolvulus lineatus L., whose populations are often highly reduced in spatial extent and are currently being fragmented by land development projects in Mediterranean France. To do so, we quantify fruit production in a range of populations of different size over four years and perform a series of hand-pollination experiments in natural populations to assess whether fruit set is limited by mate availability. We found that C. lineatus is a self-incompatible species that shows extremely low values of fruit set in natural populations and that a principal cause of this low fruit set is a lack of compatible pollen. This may be primarily due to clonal spread that causes individual populations to be comprised of patches containing one or very few incompatibility types. In small populations fragmented by human activities and which show an absence of fruit production, we thus argue that genetic rescue represents a promising conservation management strategy to avoid inevitable long-term future population decline. We discuss how best to introduce new genetic material into the study populations. 相似文献
9.
Paolo Maiuri Emmanuel Terriac Perrine Paul-Gilloteaux Timothée Vignaud Krista McNally James Onuffer Kurt Thorn Phuong A. Nguyen Nefeli Georgoulia Daniel Soong Asier Jayo Nina Beil Jürgen Beneke Joleen Chooi Hong Lim Chloe Pei-Ying Sim Yeh-Shiu Chu Andrea Jiménez-Dalmaroni Manuel Théry 《Current biology : CB》2013,23(1):97
10.
Hai-Ha Le Chadia El-Khatib Margaux Mombled Frédéric Guitarian Muaamar Al-Gobari Mor Fall Perrine Janiaud Ivanny Marchant Michel Cucherat Théodora Bejan-Angoulvant Fran?ois Gueyffier 《PloS one》2016,11(2)