全文获取类型
收费全文 | 30335篇 |
免费 | 1736篇 |
国内免费 | 1041篇 |
专业分类
化学 | 10490篇 |
晶体学 | 364篇 |
力学 | 943篇 |
综合类 | 121篇 |
数学 | 10153篇 |
物理学 | 11041篇 |
出版年
2023年 | 183篇 |
2022年 | 320篇 |
2021年 | 320篇 |
2020年 | 399篇 |
2019年 | 698篇 |
2018年 | 488篇 |
2017年 | 499篇 |
2016年 | 437篇 |
2015年 | 441篇 |
2014年 | 492篇 |
2013年 | 1661篇 |
2012年 | 827篇 |
2011年 | 1346篇 |
2010年 | 843篇 |
2009年 | 1265篇 |
2008年 | 1382篇 |
2007年 | 1455篇 |
2006年 | 1353篇 |
2005年 | 960篇 |
2004年 | 1328篇 |
2003年 | 1454篇 |
2002年 | 2002篇 |
2001年 | 1984篇 |
2000年 | 1812篇 |
1999年 | 1951篇 |
1998年 | 1693篇 |
1997年 | 1041篇 |
1996年 | 571篇 |
1995年 | 334篇 |
1994年 | 287篇 |
1993年 | 184篇 |
1992年 | 165篇 |
1991年 | 135篇 |
1990年 | 213篇 |
1989年 | 203篇 |
1988年 | 132篇 |
1987年 | 109篇 |
1986年 | 172篇 |
1985年 | 225篇 |
1984年 | 209篇 |
1983年 | 89篇 |
1982年 | 156篇 |
1981年 | 262篇 |
1980年 | 249篇 |
1979年 | 126篇 |
1978年 | 178篇 |
1977年 | 120篇 |
1976年 | 77篇 |
1975年 | 81篇 |
1974年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Thies Dirksmeyer Paul Stahl Dr. Cecilia Vallet Prof. Dr. Shirley Knauer Prof. Dr. Michael Giese Prof. Dr. Carsten Schmuck Dr. Christoph Hirschhäuser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202104618
A transfection vector that can home in on tumors is reported. Whereas previous vectors that allow moderately cell selective gene transfection used larger systems, this small-molecule approach paved the way for precise structure-activity relationship optimization. For this, biotin, which mediates cell selectivity, was combined with the potent DNA-binding motif tetralysine-guanidinocarbonypyrrol via a hydrophilic linker, thus enabling SAR-based optimization. The new vector mediated biotin receptor (BR)-selective transfection of cell lines with different BR expression levels. Computer-based analyses of microscopy images revealed a preference of one order of magnitude for the BR-positive cell lines over the BR-negative controls. 相似文献
62.
63.
64.
Balázs Gerencsér 《Stochastic Processes and their Applications》2019,129(9):3570-3584
The paper concerns a particular example of the Gibbs sampler and its mixing efficiency. Coordinates of a point are rerandomized in the unit square to approach a stationary distribution with density proportional to for with some large parameter .Diaconis conjectured the mixing time of this process to be which we confirm in this paper. This improves on the currently known estimate. 相似文献
65.
66.
67.
68.
Let K and S be locally compact Hausdorff spaces and let X be a strictly convex Banach space of finite dimension at least 2. In this paper, we prove that if there exists an isomorphism T from onto satisfying then K and S are homeomorphic. Here denotes the Schäffer constant of X. Even for the classical cases , and , this result is the X‐valued Banach–Stone theorem via isomorphism with the largest distortion that is known so far, namely . On the other hand, it is well known that this result is not true for , even though K and S are compact Hausdorff spaces. 相似文献
69.
In this article, we study for the ‐realization of the vector‐valued Schrödinger operator . Using a noncommutative version of the Dore–Venni theorem due to Monniaux and Prüss, we prove that the ‐realization of , defined on the intersection of the natural domains of the differential and multiplication operators which form , generates a strongly continuous contraction semigroup on . We also study additional properties of the semigroup such as extension to L1, positivity, ultracontractivity and prove that the generator has compact resolvent. 相似文献
70.
We prove that a WLD subspace of the space consisting of all bounded, countably supported functions on a set Γ embeds isomorphically into if and only if it does not contain isometric copies of . Moreover, a subspace of is constructed that has an unconditional basis, does not embed into , and whose every weakly compact subset is separable (in particular, it cannot contain any isomorphic copies of ). 相似文献