全文获取类型
收费全文 | 12802篇 |
免费 | 1144篇 |
国内免费 | 3篇 |
出版年
2023年 | 68篇 |
2022年 | 149篇 |
2021年 | 361篇 |
2020年 | 194篇 |
2019年 | 246篇 |
2018年 | 328篇 |
2017年 | 282篇 |
2016年 | 443篇 |
2015年 | 723篇 |
2014年 | 784篇 |
2013年 | 931篇 |
2012年 | 1078篇 |
2011年 | 1108篇 |
2010年 | 691篇 |
2009年 | 543篇 |
2008年 | 813篇 |
2007年 | 832篇 |
2006年 | 670篇 |
2005年 | 621篇 |
2004年 | 614篇 |
2003年 | 470篇 |
2002年 | 440篇 |
2001年 | 113篇 |
2000年 | 97篇 |
1999年 | 91篇 |
1998年 | 98篇 |
1997年 | 72篇 |
1996年 | 68篇 |
1995年 | 80篇 |
1994年 | 60篇 |
1993年 | 47篇 |
1992年 | 43篇 |
1991年 | 49篇 |
1990年 | 44篇 |
1989年 | 44篇 |
1988年 | 34篇 |
1987年 | 33篇 |
1986年 | 34篇 |
1985年 | 28篇 |
1984年 | 52篇 |
1983年 | 28篇 |
1982年 | 25篇 |
1981年 | 32篇 |
1980年 | 26篇 |
1978年 | 20篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1970年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
1.
An perfusion system was used to assess the effects of chloride channel blockers, dopamine (DA) receptor agonists and antagonists, and GABA receptor agonists and antagonists on prolactin release from the mouse anterior pituitary. Dopamine and muscimol inhibited prolactin release ( respectively). The GABA receptor antagonist bicuculline blocked the inhibition of prolactin release by muscimol but not dopamine. The dopamine receptor antagonist chlorpromazine blocked the dopamine- but not muscimol-induced inhibition of prolactin release. Haloperidol, however, reversed both the muscimol and dopamine induced inhibition of prolactin release. Furthermore, the chloride channel blocker picrotoxinin blocked the inhibition of prolactin release elicited by both dopamine and muscimol. These later results suggest that the anterior pituitary dopamine receptor which mediates the inhibition of prolactin release may be coupled to a picrotoxinin sensitive chloride ionophore and that haloperidol may affect the function of both DA and GABA receptors in the anterior pituitary. 相似文献
2.
Zhaolin Wang Cara Fraley Adam R. Mezo 《Bioorganic & medicinal chemistry letters》2013,23(5):1253-1256
The neonatal Fc receptor, FcRn, prolongs the half-life of IgG in the serum and represents a potential therapeutic target for the treatment of autoimmune disease. Small molecules that block the protein–protein interactions of human IgG–human FcRn may lower pathogenic autoantibodies and provide effective treatment. A novel class of quinoxalines has been discovered as antagonists of the IgG:FcRn protein–protein interaction through optimization of a hit derived from a virtual ligand-based screen. 相似文献
3.
4.
Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research... 相似文献
5.
6.
Hierarchy and monophyly 总被引:1,自引:0,他引:1
7.
Eliot C. Bush Anne E. Clark Chris M. DeBoever Lillian E. Haynes Sidra Hussain Singer Ma Matthew M. McDermott Adam M. Novak John S. Wentworth 《PloS one》2012,7(11)
A significant proportion of enzymes display cooperativity in binding ligand molecules, and such effects have an important impact on metabolic regulation. This is easiest to understand in the case of positive cooperativity. Sharp responses to changes in metabolite concentrations can allow organisms to better respond to environmental changes and maintain metabolic homeostasis. However, despite the fact that negative cooperativity is almost as common as positive, it has been harder to imagine what advantages it provides. Here we use computational models to explore the utility of negative cooperativity in one particular context: that of an inhibitor binding to an enzyme. We identify several factors which may contribute, and show that acting together they can make negative cooperativity advantageous. 相似文献
8.
9.
A Adam J Damas P Franchimont 《Comptes rendus des séances de la Société de biologie et de ses filiales》1980,174(5):856-862
A radioimmunoassay for low molecular weight (LMW) human Kininogen has been carried out. The first step was to prepare LMW Kininogen from human plasma. The proposed method allowed to get chemically pure and biologically active LMW Kininogen. This preparation was used to induce antibody. Optimal conditions for labelling and incubation were determined. This method may be applied to the assay of Kininogen in human plasma. 相似文献
10.
Dysfunctional pulmonary homeostasis and repair, including diseases such as pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD), and tumorigenesis have been increasing over the past decade, a fact that heavily implicates environmental influences. Several investigations have suggested that in response to increased transforming growth factor - beta (TGFβ) signaling, the alveolar type II (ATII) epithelial cell undergoes phenotypic changes that may contribute to the complex pathobiology of PF. We have previously demonstrated that increased tissue stiffness associated with PF is a potent extracellular matrix (ECM) signal for epithelial cell activation of TGFβ. The work reported here explores the relationship between tissue stiffness and exposure to environmental stimuli in the activation of TGFβ. We hypothesized that exposure of ATII cells to fine particulate matter (PM2.5) will result in enhanced cell contractility, TGFβ activation, and subsequent changes to ATII cell phenotype. ATII cells were cultured on increasingly stiff substrates with or without addition of PM2.5. Exposure to PM2.5 resulted in increased activation of TGFβ, increased cell contractility, and elongation of ATII cells. Most notably, on 8 kPa substrates, a stiffness greater than normal but less than established fibrotic lung, addition of PM2.5 resulted in increased cortical cell stiffness, enhanced actin staining and cell elongation; a result not seen in the absence of PM2.5. Our work suggests that PM2.5 exposure additionally enhances the existing interaction between ECM stiffness and TGFβ that has been previously reported. Furthermore, we show that this additional enhancement is likely a consequence of intracellular reactive oxygen species (ROS) leading to increased TGFβ signaling events. These results highlight the importance of both the micromechanical and biochemical environment in lung disease initiation and suggest that individuals in early stages of lung remodeling during fibrosis may be more susceptible than healthy individuals when exposed to environmental injury adjuvants. 相似文献