全文获取类型
收费全文 | 987篇 |
免费 | 2篇 |
国内免费 | 6篇 |
专业分类
系统科学 | 6篇 |
丛书文集 | 1篇 |
教育与普及 | 3篇 |
理论与方法论 | 32篇 |
现状及发展 | 362篇 |
研究方法 | 119篇 |
综合类 | 450篇 |
自然研究 | 22篇 |
出版年
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 9篇 |
2012年 | 55篇 |
2011年 | 64篇 |
2010年 | 20篇 |
2009年 | 6篇 |
2008年 | 29篇 |
2007年 | 32篇 |
2006年 | 48篇 |
2005年 | 26篇 |
2004年 | 45篇 |
2003年 | 39篇 |
2002年 | 25篇 |
2001年 | 32篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1996年 | 5篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 16篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 8篇 |
1975年 | 16篇 |
1974年 | 24篇 |
1973年 | 16篇 |
1972年 | 21篇 |
1971年 | 12篇 |
1970年 | 17篇 |
1969年 | 15篇 |
1968年 | 24篇 |
1967年 | 13篇 |
1966年 | 13篇 |
1965年 | 13篇 |
1964年 | 7篇 |
排序方式: 共有995条查询结果,搜索用时 15 毫秒
91.
E A Rogaeva S Premkumar J Grubber L Serneels W K Scott T Kawarai Y Song D L Hill S M Abou-Donia E R Martin J J Vance G Yu A Orlacchio Y Pei M Nishimura A Supala B Roberge A M Saunders A D Roses D Schmechel A Crane-Gatherum S Sorbi A Bruni G W Small P M Conneally J L Haines F Van Leuven P H St George-Hyslop L A Farrer M A Pericak-Vance 《Nature genetics》1999,22(1):19-22
92.
P S Ohashi T W Mak P Van den Elsen Y Yanagi Y Yoshikai A F Calman C Terhorst J D Stobo A Weiss 《Nature》1985,316(6029):606-609
93.
Changes in the expression of class II antigens of the major histocompatibility complex (MHC) have an integral role in the regulation of immune responses, and are brought about in vitro by soluble mediators. However, the mechanism that underlies in vivo expression of MHC class II antigens in, for example, endothelial cells in the absence of immunological stimulation has not been studied. We demonstrate here that expression of MHC class II antigens is not a constitutive property of endothelial cells, for MHC class II antigen-positive endothelial cells do not express these antigens during treatment with the immunosuppressive agent cyclosporin A. In vivo MHC class II antigen expression by canine endothelial cells is therefore dependent on factors, probably the lymphokine gamma-interferon produced by the immune system, whose secretion is inhibited by cyclosporin A. 相似文献
94.
95.
96.
B. L. van der Waerden 《Archive for History of Exact Sciences》1978,18(4):343-357
Ohne Zusammenfassung 相似文献
97.
H. Van Dael 《Cellular and molecular life sciences : CMLS》1998,54(11):1217-1230
Protein folding is an extremely active field of research where biology, chemistry, computer science and physics meet. Although
the study of protein-folding intermediates in general and equilibrium intermediates in particular has grown considerably in
recent years, many questions regarding the conformational state and the structural features of the various partially folded
intermediate states remain unanswered. Performing kinetic measurements on proteins that have had their structures modified
by site-directed mutagenesis, the so-called protein-engineering method, is an obvious way to gain fine structural information.
In the present review, this method has been applied to a variety of proteins belonging to the lysozyme/α-lactalbumin family. Besides recombinants obtained by point mutations of individual critical residues, chimeric proteins in
which whole structural elements (10 – 25 residues) from α-lactalbumin were inserted into a human lysozyme matrix are examined. The conformational properties of the equilibrium intermediate
states are discussed together with the structural characterization of the partially unfolded states encountered in the kinetic
folding pathway.
Received 28 May 1998; received after revision 6 July 1998; accepted 6 July 1998 相似文献
98.
Regulated expression and binding of three VLA (beta 1) integrin receptors on T cells 总被引:78,自引:0,他引:78
Regulated adhesion of T cells to extracellular matrix (ECM) proteins is likely to be essential in T cell migration. Constitutive binding of various other cell types to ECM components is mediated by members of the VLA (very late antigen) subfamily of integrins. We describe here the regulated binding of resting CD4+ human T cells to ECM through three VLA integrins: VLA-4 and VLA-5 binding to fibronectin (FN), and a novel pathway of VLA-6 binding to laminin (LN). Binding to ECM is regulated in two ways. First, unlike other VLA-mediated interactions, VLA binding activity of the T cells is rapidly and dramatically augmented with cell activation without change in level of expression of the VLA molecules. Second, binding is regulated with T-cell differentiation; memory T cells express three- to four-fold more VLA-4, VLA-5, and VLA-6 than do naive cells, and bind more efficiently through them to FN and LN. 相似文献
99.
100.