全文获取类型
收费全文 | 5456篇 |
免费 | 452篇 |
国内免费 | 3篇 |
专业分类
5911篇 |
出版年
2023年 | 33篇 |
2022年 | 55篇 |
2021年 | 106篇 |
2020年 | 75篇 |
2019年 | 87篇 |
2018年 | 107篇 |
2017年 | 96篇 |
2016年 | 145篇 |
2015年 | 237篇 |
2014年 | 246篇 |
2013年 | 313篇 |
2012年 | 411篇 |
2011年 | 378篇 |
2010年 | 298篇 |
2009年 | 235篇 |
2008年 | 343篇 |
2007年 | 321篇 |
2006年 | 282篇 |
2005年 | 305篇 |
2004年 | 249篇 |
2003年 | 225篇 |
2002年 | 235篇 |
2001年 | 77篇 |
2000年 | 50篇 |
1999年 | 63篇 |
1998年 | 80篇 |
1997年 | 48篇 |
1996年 | 66篇 |
1995年 | 47篇 |
1994年 | 45篇 |
1993年 | 47篇 |
1992年 | 44篇 |
1991年 | 43篇 |
1990年 | 29篇 |
1989年 | 25篇 |
1988年 | 30篇 |
1987年 | 32篇 |
1986年 | 19篇 |
1985年 | 39篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 29篇 |
1981年 | 21篇 |
1980年 | 28篇 |
1979年 | 18篇 |
1978年 | 16篇 |
1977年 | 19篇 |
1976年 | 22篇 |
1974年 | 16篇 |
1973年 | 21篇 |
排序方式: 共有5911条查询结果,搜索用时 12 毫秒
91.
Robin D. Graham 《Plant and Soil》1980,56(1):181-185
Summary Wheat plants were grown in deep pots at three levels of copper nutrition in an open-sided glasshouse where they were subject to natural infection by powdery mildew. Plant growth and the degree of infection of each leaf were assessed weekly throughout the life of the plants.During the middle phase of growth especially — from tillering to anthesis — severity of infection of leaves was decreased by increasing the level of copper supply. Stems of copper-deficient plants were also severely infected. In these plants serious disease was sustained until final harvest. The results are discussed in relation to known and speculative roles of copper in plants. 相似文献
92.
93.
94.
Pulse-labeled oocyte proteins were found to have a maximum average half-life of 73 h. In general, larger peptides underwent degradation at a faster rate than smaller peptides. In this respect, oocytes are similar to most other cells. Microinjected 125I-labeled bovine serum albumin (BSA) was degraded over a 40 h period with a half-life of 20–30 h, regardless of the method of protein labeling, culture medium employed, size of oocyte microinjected, or hormonal history of the oocyte. The last two results, if applicable to oocyte proteins in general, imply that protein catabolism is constant throughout the later stages of oogenesis and that growth is primarily regulated by a stimulation of anabolism. Individual proteins microinjected into oocytes undergo rates of degradation consistent with turnover rates obtained in other systems. Sequestered 125I-labeled BSA is only partially (40%) degraded, which indicates that, unlike microinjected 125I-labeled BSA, it has access to a cytoplasmic compartment (yolk platelets?) within which it is relatively stable. 相似文献
95.
96.
97.
Protonemata of Onoclea sensibilis and Diyopteris filix-mas elongate in response to both red and far-red light. The promotion caused by far-red is larger than that caused by red light. This phenomenon differs from a typical response to phytochrome, the photoreceptor pigment immediately suggested by the activity of red and far-red light. The phenomenon has been explained by two different hypotheses, one of which holds that phytochrome is solely responsible for the response, whereas the other postulates an interaction between phytochrome and P580, a yellow-green light absorbing pigment, to account for the response. The hypothesis that phytochrome is the sole photoreceptor leads to some specific predictions concerning the shapes of the dose-response curves for light-induced protonema elongation. These predictions were tested with both continuous and short-term irradiation. In all instances saturating far-red light caused greater elongation than did saturating red light, and no dose of red light duplicated the activity of saturating far-red light. Other experiments tested the interactions of red and far-red light and the effects of different doses of yellow-green light on protonema elongation. The results of many of the experiments were not in agreement with the hypothesis that phytochrome is the sole photoreceptor, whereas they were in agreement with the assumption that filament elongation is controlled by both phytochrome and P580. 相似文献
98.
Ceniz Zihni Anastasios Georgiadis Conor M. Ramsden Elena Sanchez-Heras Alexis J. Haas Britta Nommiste Olha Semenyuk James W.B. Bainbridge Peter J. Coffey Alexander J. Smith Robin R. Ali Maria S. Balda Karl Matter 《The Journal of cell biology》2022,221(11)
Phagocytosis requires actin dynamics, but whether actomyosin contractility plays a role in this morphodynamic process is unclear. Here, we show that in the retinal pigment epithelium (RPE), particle binding to Mer Tyrosine Kinase (MerTK), a widely expressed phagocytic receptor, stimulates phosphorylation of the Cdc42 GEF Dbl3, triggering activation of MRCKβ/myosin-II and its coeffector N-WASP, membrane deformation, and cup formation. Continued MRCKβ/myosin-II activity then drives recruitment of a mechanosensing bridge, enabling cytoskeletal force transmission, cup closure, and particle internalization. In vivo, MRCKβ is essential for RPE phagocytosis and retinal integrity. MerTK-independent activation of MRCKβ signaling by a phosphomimetic Dbl3 mutant rescues phagocytosis in retinitis pigmentosa RPE cells lacking functional MerTK. MRCKβ is also required for efficient particle translocation from the cortex into the cell body in Fc receptor–mediated phagocytosis. Thus, conserved MRCKβ signaling at the cortex controls spatiotemporal regulation of actomyosin contractility to guide distinct phases of phagocytosis in the RPE and represents the principle phagocytic effector pathway downstream of MerTK. 相似文献
99.
Alice J L Zheng Aikaterini Thermou Chrysoula Daskalogianni Laurence Malbert-Colas Konstantinos Karakostis Ronan Le
Snchal Van Trang
Dinh Maria C Tovar
Fernandez Sbastien Apcher Sa Chen Marc Blondel Robin Fahraeus 《Nucleic acids research》2022,50(17):10110
Protein aggregates and abnormal proteins are toxic and associated with neurodegenerative diseases. There are several mechanisms to help cells get rid of aggregates but little is known on how cells prevent aggregate-prone proteins from being synthesised. The EBNA1 of the Epstein-Barr virus (EBV) evades the immune system by suppressing its own mRNA translation initiation in order to minimize the production of antigenic peptides for the major histocompatibility (MHC) class I pathway. Here we show that the emerging peptide of the disordered glycine–alanine repeat (GAr) within EBNA1 dislodges the nascent polypeptide-associated complex (NAC) from the ribosome. This results in the recruitment of nucleolin to the GAr-encoding mRNA and suppression of mRNA translation initiation in cis. Suppressing NAC alpha (NACA) expression prevents nucleolin from binding to the GAr mRNA and overcomes GAr-mediated translation inhibition. Taken together, these observations suggest that EBNA1 exploits a nascent protein quality control pathway to regulate its own rate of synthesis that is based on sensing the nascent GAr peptide by NAC followed by the recruitment of nucleolin to the GAr-encoding RNA sequence. 相似文献