全文获取类型
收费全文 | 2024篇 |
免费 | 199篇 |
国内免费 | 1篇 |
出版年
2021年 | 35篇 |
2020年 | 21篇 |
2019年 | 28篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 35篇 |
2015年 | 68篇 |
2014年 | 79篇 |
2013年 | 119篇 |
2012年 | 97篇 |
2011年 | 86篇 |
2010年 | 57篇 |
2009年 | 58篇 |
2008年 | 72篇 |
2007年 | 69篇 |
2006年 | 81篇 |
2005年 | 62篇 |
2004年 | 52篇 |
2003年 | 45篇 |
2002年 | 55篇 |
2001年 | 74篇 |
2000年 | 39篇 |
1999年 | 30篇 |
1998年 | 25篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 23篇 |
1993年 | 17篇 |
1992年 | 39篇 |
1991年 | 34篇 |
1990年 | 25篇 |
1989年 | 30篇 |
1988年 | 34篇 |
1987年 | 40篇 |
1986年 | 34篇 |
1985年 | 36篇 |
1984年 | 25篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 29篇 |
1977年 | 18篇 |
1976年 | 23篇 |
1974年 | 29篇 |
1973年 | 24篇 |
1972年 | 16篇 |
1971年 | 21篇 |
1969年 | 16篇 |
排序方式: 共有2224条查询结果,搜索用时 531 毫秒
121.
122.
Hansford Kayleigh M. McGinley Liz Wilkinson Samantha Gillingham Emma L. Cull Ben Gandy Sara Carter Daniel P. Vaux Alexander G. C. Richards Simon Hayes Alister Medlock Jolyon M. 《Experimental & applied acarology》2021,84(3):593-606
Experimental and Applied Acarology - Assessing the risk of tick-borne disease in areas with high visitor numbers is important from a public health perspective. Evidence suggests that tick presence,... 相似文献
123.
Human Ecology - I address a contentious element in forest property relations to illustrate the role of ownership in protecting and expanding of forest cover by examining the extent to... 相似文献
124.
Alena Bartukov Arinawa Liz Filartiga Tom Herben Jianqiang Qian Jitka Klimeov 《Annals of botany》2021,127(7):931
Background and AimsRoot sprouting (RS), i.e. the ability to form adventitious buds on roots, is an important form of clonal growth in a number of species, and serves as both a survival strategy and a means of spatial expansion, particularly in plants growing in severely and recurrently disturbed habitats. Occurrence and/or success of plants in severely and recurrently disturbed habitats are determined by two components, namely the ability to produce adventitious buds on roots and the vigour of their production. As mechanisms behind different magnitudes of RS remain unclear, our study investigates: (1) whether the presence or absence of specific tissues in roots can promote or limit RS; and (2) whether there is some relationship between RS ability, RS vigour and species niche.MethodsWe studied RS ability together with RS vigour in 182 Central European herbaceous species under controlled experimental conditions. We used phylogenetic logistic regressions to model the presence of RS, RS vigour, the relationship between RS and anatomical traits and the relationship between RS and parameters of species niches.Key ResultsA quarter of herbs examined were able to produce adventitious buds on roots. They were characterized by their preference for open dry habitats, the presence of secondary root thickening and the occurrence of sclerified cortical cells in roots. Root sprouting vigour was not associated with any specific anatomical pattern, but was correlated with the environmental niches of different species, indicating that preferred disturbed and dry habitats might represent a selection pressure for more vigorous root sprouters than undisturbed and wet habitats.ConclusionsOur study shows that sprouting from roots is quite common in temperate dicotyledonous herbs. Two components of RS – ability and vigour – should be considered separately in future studies. We would also like to focus more attention on RS in herbs from other regions as well as on external forces and internal mechanisms regulating evolution and the functions of RS in both disturbed and undisturbed habitats. 相似文献
125.
Transcriptomic Profiling of Human Pluripotent Stem Cell-derived Retinal Pigment Epithelium over Time
126.
Seung Ho Jung Arpit Saxena Kamaljeet Kaur Emma Fletcher Venkatesh Ponemone James M. Nottingham Joseph A. Sheppe Maria Petroni Jennifer Greene Kelly Graves Manjeshwar Shrinath Baliga Raja Fayad 《Cytokine》2013,61(2):459-468
Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the gastrointestinal tract that affect more than 3 million people worldwide, but the pathological etiology is still unknown. The overall purpose of our investigations was to elucidate the possibility of pathological causes of IBD, and therefore, we determined the difference of inflammatory cytokine profiles in adipose tissue macrophages (ATMs) and T lymphocytes (ATTs) obtained near active lesions of IBD; investigated whether the alteration in ATM activation induces genes involved in collagen formation; and evaluated the effects of fatty acid oxidation inhibitors on factors involved in inflammation and collagen production by ATMs in IBD. Adipose tissues (ATs) were collected near active lesions and also at the margin of resected segments of the bowel from IBD patients with ulcerative colitis (UC) and CD (n = 14/group). Normal appearing ATs from control subjects (n = 14) who had colon resection for adenocarcinoma were collected as far away from the cancer lesion as possible to rule out possible changes. Compared with inactive disease lesions, ATMs and ATTs from active lesions released more IL-6, IL-4 and IL-13. Treatments of cytokine IL-4 and/or IL-13 to ATMs reduced iNOS expression but increased Arg-I expression which were exacerbated when treated with T cell- and adipocyte-conditioned medium. However, fatty acid oxidation inhibitors prevented the effects of cytokines IL-4 and/or IL-13 on iNOS and Arg-I expressions. This study was the first to show the effect of IL-4 and IL-13 on collagen formation, through iNOS and Arg-I expressions, that was exacerbated in a condition that mimics in vivo condition of active lesions. Moreover, our study was the first to provide potential benefits of fatty acid oxidation inhibitors to ATMs on preventing collagen formation; thus, providing therapeutic implications for individuals with intestinal fibrosis and stricture lesions, although future study should be guaranteed to elucidate the underlying mechanisms. 相似文献
127.
Amy L. Fletcher 《New genetics and society》2013,32(1):3-14
This case study of the Estonian Genome Project (EGP) analyses the Estonian policy decision to construct a national human gene bank. Drawing upon qualitative data from newspaper articles and public policy documents, it focuses on how proponents use discourse to link the EGP to the broader political goal of securing Estonia's position within the Western/European scientific and cultural space. This dominant narrative is then situated within the analytical notion of the “brand state”, which raises potentially negative political consequences for this type of market‐driven genomic research. Considered against the increasing number of countries engaging in gene bank and/or gene database projects, this analysis of Estonia elucidates issues that cross national boundaries, while also illuminating factors specific to this small, post‐Soviet state as it enters the global biocybernetic economy. 相似文献
128.
129.
Background
Recent experimental evidence suggests that stressed males find heavier women more attractive than non-stressed males. The aim of this study is to examine whether these results also appear in actual mating patterns of adults from a national sample.Methods
Regression analysis linking partner weight measures to own measures of childhood stress, as measured by mistreatment. Cross-sectional data from the National Longitudinal Study of Adolescent Health, Romantic Partners Sample is used to measure partner weight, childhood stressful events, and socio-demographic characteristics. Childhood experiences of adult mistreatment are retrospectively collected.Results
Men who experienced childhood mistreatment are more likely to have obese female partners during young adulthood. The results are strongest for interactions with social services, adult neglect and physical abuse. We also present novel evidence of the opposite association in similarly stressed women whose male partners are more likely to be thin.Conclusions
These results suggest that preferences for partner characteristics are sensitive to histories of stress and that previously hypothesized patterns occur outside the experimental setting. 相似文献130.
Suzanna E. Forwood Amy Ahern Gareth J. Hollands Paul C. Fletcher Theresa M. Marteau 《PloS one》2013,8(8)