全文获取类型
收费全文 | 29419篇 |
免费 | 798篇 |
国内免费 | 727篇 |
专业分类
化学 | 3976篇 |
晶体学 | 851篇 |
力学 | 529篇 |
综合类 | 74篇 |
数学 | 22564篇 |
物理学 | 2950篇 |
出版年
2023年 | 79篇 |
2022年 | 102篇 |
2021年 | 154篇 |
2020年 | 181篇 |
2019年 | 661篇 |
2018年 | 693篇 |
2017年 | 422篇 |
2016年 | 427篇 |
2015年 | 396篇 |
2014年 | 855篇 |
2013年 | 1654篇 |
2012年 | 909篇 |
2011年 | 1914篇 |
2010年 | 1856篇 |
2009年 | 2100篇 |
2008年 | 2283篇 |
2007年 | 2269篇 |
2006年 | 1719篇 |
2005年 | 1267篇 |
2004年 | 1168篇 |
2003年 | 893篇 |
2002年 | 731篇 |
2001年 | 595篇 |
2000年 | 555篇 |
1999年 | 614篇 |
1998年 | 559篇 |
1997年 | 458篇 |
1996年 | 606篇 |
1995年 | 564篇 |
1994年 | 558篇 |
1993年 | 474篇 |
1992年 | 419篇 |
1991年 | 288篇 |
1990年 | 230篇 |
1989年 | 250篇 |
1988年 | 162篇 |
1987年 | 188篇 |
1986年 | 168篇 |
1985年 | 266篇 |
1984年 | 209篇 |
1983年 | 124篇 |
1982年 | 192篇 |
1981年 | 170篇 |
1980年 | 120篇 |
1979年 | 91篇 |
1978年 | 109篇 |
1977年 | 92篇 |
1976年 | 78篇 |
1975年 | 20篇 |
1974年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Pavitra Laohapaisan Kanyapat Lumyong Jumreang Tummatorn Charnsak Thongsornkleeb Jaruwan Chatwichien Nantamon Supantanapong Somsak Ruchirawat 《化学:亚洲杂志》2022,17(1):e202101212
ortho-Alkynylarylketone derivatives were employed as key precursors for a one-pot synthesis of arylnaphthalenelactone and furanonaphthol libraries. In this work, we discovered a cost-effective protocol to prepare arylnaphthalenelactones in one-pot using inexpensive starting material, malonate ester, which was conveniently functionalized leading to a variety of structures. Moreover, we also found an unexpected oxy-dearylation reaction which could be used to synthesize furanonaphthol analogs. These novel methods could be applied to a broad range of substrates to give the corresponding products in up to 83% yield. Notably, these classes of compounds exhibited more significant inhibition against protein-tyrosine phosphatase 1B (PTP1B) enzyme than a standard compound, ursolic acid. 相似文献
2.
3.
《Journal of Pure and Applied Algebra》2022,226(10):107043
We use the machinery of categorified Jones-Wenzl projectors to construct a categorification of a type A Reshetikhin-Turaev invariant of oriented framed tangles where each strand is labelled by an arbitrary finite-dimensional representation. As a special case, we obtain a categorification of the coloured Jones polynomial of links. 相似文献
4.
5.
6.
7.
《Mathematische Nachrichten》2018,291(8-9):1177-1190
We introduce homogeneous Besov and Triebel–Lizorkin spaces with variable indexes. We show that their study reduces to the study of inhomogeneous variable exponent spaces and homogeneous constant exponent spaces. Corollaries include trace space characterizations and Sobolev embeddings. 相似文献
8.
We prove a sharp estimate for the k-modulus of smoothness, modelled upon a -Lebesgue space, of a function f in , where Ω is a domain with minimally smooth boundary and finite Lebesgue measure, , and . This sharp estimate is used to establish necessary and sufficient conditions for continuous embeddings of Sobolev-type spaces into generalized Hölder spaces defined by means of the k-modulus of smoothness. General results are illustrated with examples. In particular, we obtain a generalization of the classical Jawerth embeddings. 相似文献
9.
In this paper we study the domain of the generator of stable processes, stable-like processes and more general pseudo- and integro-differential operators which naturally arise both in analysis and as infinitesimal generators of Lévy- and Lévy-type (Feller) processes. In particular we obtain conditions on the symbol of the operator ensuring that certain (variable order) Hölder and Hölder–Zygmund spaces are in the domain. We use tools from probability theory to investigate the small-time asymptotics of the generalized moments of a Lévy or Lévy-type process , for functions f which are not necessarily bounded or differentiable. The pointwise limit exists for fixed if f satisfies a Hölder condition at x. Moreover, we give sufficient conditions which ensure that the limit exists uniformly in the space of continuous functions vanishing at infinity. As an application we prove that the domain of the generator of contains certain Hölder spaces of variable order. Our results apply, in particular, to stable-like processes, relativistic stable-like processes, solutions of Lévy-driven SDEs and Lévy processes. 相似文献
10.