全文获取类型
收费全文 | 8223篇 |
免费 | 510篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 63篇 |
儿科学 | 132篇 |
妇产科学 | 108篇 |
基础医学 | 1079篇 |
口腔科学 | 233篇 |
临床医学 | 851篇 |
内科学 | 1630篇 |
皮肤病学 | 110篇 |
神经病学 | 953篇 |
特种医学 | 581篇 |
外科学 | 1466篇 |
综合类 | 31篇 |
一般理论 | 1篇 |
预防医学 | 248篇 |
眼科学 | 189篇 |
药学 | 478篇 |
中国医学 | 14篇 |
肿瘤学 | 606篇 |
出版年
2024年 | 9篇 |
2023年 | 89篇 |
2022年 | 195篇 |
2021年 | 399篇 |
2020年 | 203篇 |
2019年 | 248篇 |
2018年 | 308篇 |
2017年 | 230篇 |
2016年 | 359篇 |
2015年 | 380篇 |
2014年 | 464篇 |
2013年 | 493篇 |
2012年 | 774篇 |
2011年 | 705篇 |
2010年 | 422篇 |
2009年 | 367篇 |
2008年 | 567篇 |
2007年 | 499篇 |
2006年 | 438篇 |
2005年 | 418篇 |
2004年 | 339篇 |
2003年 | 329篇 |
2002年 | 230篇 |
2001年 | 33篇 |
2000年 | 26篇 |
1999年 | 36篇 |
1998年 | 32篇 |
1997年 | 27篇 |
1996年 | 6篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有8773条查询结果,搜索用时 15 毫秒
101.
Florian Cymer Gunnar von Heijne 《Proceedings of the National Academy of Sciences of the United States of America》2013,110(36):14640-14645
Polytopic membrane proteins are inserted cotranslationally into target membranes by ribosome–translocon complexes. It is, however, unclear when during the insertion process specific interactions between the transmembrane helices start to form. Here, we use a recently developed in vivo technique to measure pulling forces acting on transmembrane helices during their cotranslational insertion into the inner membrane of Escherichia coli to study the earliest steps of tertiary folding of five polytopic membrane proteins. We find that interactions between residues in a C-terminally located transmembrane helix and in more N-terminally located helices can be detected already at the point when the C-terminal helix partitions from the translocon into the membrane. Our findings pinpoint the earliest steps of tertiary structure formation and open up possibilities to study the cotranslational folding of polytopic membrane proteins. 相似文献
102.
Search engines are increasingly used to seek suicide-related information online, which can serve both harmful and helpful purposes. Google acknowledges this fact and presents a suicide-prevention result for particular search terms. Unfortunately, the result is only presented to a limited number of visitors. Hence, Google is missing the opportunity to provide help to vulnerable people. We propose a two-step approach to a tailored optimization: First, research will identify the risk factors. Second, search engines will reweight algorithms according to the risk factors. In this study, we show that the query share of the search term “poisoning” on Google shows substantial peaks corresponding to peaks in actual suicidal behavior. Accordingly, thresholds for showing the suicide-prevention result should be set to the lowest levels during the spring, on Sundays and Mondays, on New Year’s Day, and on Saturdays following Thanksgiving. Search engines can help to save lives globally by utilizing a more tailored approach to suicide prevention. 相似文献
103.
Florian Eisel Meike Boosen Martina Beck Heinrich Heide Ilka Wittig Karl-Friedrich Beck Josef Pfeilschifter 《Biochemical pharmacology》2013,85(1):101-108
Inflammatory glomerular kidney diseases are often accompanied with a massive production of reactive oxygen species (ROS) that affect the function of the glomerular filtration barrier and contribute to mesangiolysis via the induction of cell death in mesangial cells. Intriguingly, ROS also trigger fine-tuned signalling processes that affect gene expression and cell proliferation or migration. To define such redox-driven signalling devices, a proteomics approach was performed to identify the formation of protein complexes induced by ROS. To this end, protein lysates of human podocytes were treated with or without hydrogen peroxide (250 μM). Thereafter cell lysates were subjected to diagonal 2D gel electrophoresis and putative redox-affected proteins were analysed by MS/MS analysis. Among others, the regulatory subunit of protein kinase A (PKA) could be identified that forms homodimers under oxidative conditions. To evaluate whether ROS dependent dimerization of PKA also occurs in a more physiological setting, rat mesangial cells were treated with platelet-derived growth factor-BB (PDGF-BB) to induce ROS formation. This regimen resulted in a redox dependent dimerization of the R-subunits of PKA. To demonstrate whether PDGF-BB induced ROS formation affects PKA dependent pathways, the effects of PDGF-BB on phosphorylation of serine 157 of vasodilator stimulated protein (VASP) a classical target of PKA were analysed. Interestingly PDGF-BB induced VASP phosphorylation in a ROS dependent manner but independent of changes in cAMP levels. Taken together, we demonstrate a redox-mediated activation of PKA by PDGF-BB thus highlighting a physiological role of ROS as regulator of PKA activity in rat mesangial cells. 相似文献
104.
105.
106.
107.
Florian Stengel Andrew J. Baldwin Alexander J. Painter Nomalie Jaya Eman Basha Lewis E. Kay Elizabeth Vierling Carol V. Robinson Justin L. P. Benesch 《Proceedings of the National Academy of Sciences of the United States of America》2010,107(5):2007-2012
Small Heat Shock Proteins (sHSPs) are a diverse family of molecular chaperones that prevent protein aggregation by binding clients destabilized during cellular stress. Here we probe the architecture and dynamics of complexes formed between an oligomeric sHSP and client by employing unique mass spectrometry strategies. We observe over 300 different stoichiometries of interaction, demonstrating that an ensemble of structures underlies the protection these chaperones confer to unfolding clients. This astonishing heterogeneity not only makes the system quite distinct in behavior to ATP-dependent chaperones, but also renders it intractable by conventional structural biology approaches. We find that thermally regulated quaternary dynamics of the sHSP establish and maintain the plasticity of the system. This extends the paradigm that intrinsic dynamics are crucial to protein function to include equilibrium fluctuations in quaternary structure, and suggests they are integral to the sHSPs’ role in the cellular protein homeostasis network. 相似文献
108.
109.
The vast majority of new HIV infections are acquired via the genital and rectal mucosa. Here, we provide an overview of our
current knowledge of how HIV establishes local infection, with an emphasis on viral invasion through the female genital tract.
Studies using human explant tissues and in vivo animal studies have improved our understanding of the cellular and molecular
pathways of infection; this information could be harnessed to design effective HIV vaccines and microbicides. 相似文献
110.