全文获取类型
收费全文 | 21935篇 |
免费 | 3805篇 |
国内免费 | 1786篇 |
专业分类
化学 | 4650篇 |
晶体学 | 65篇 |
力学 | 3392篇 |
综合类 | 569篇 |
数学 | 9937篇 |
物理学 | 8913篇 |
出版年
2024年 | 23篇 |
2023年 | 213篇 |
2022年 | 339篇 |
2021年 | 502篇 |
2020年 | 549篇 |
2019年 | 496篇 |
2018年 | 509篇 |
2017年 | 759篇 |
2016年 | 873篇 |
2015年 | 713篇 |
2014年 | 1189篇 |
2013年 | 1536篇 |
2012年 | 1217篇 |
2011年 | 1392篇 |
2010年 | 1231篇 |
2009年 | 1380篇 |
2008年 | 1568篇 |
2007年 | 1663篇 |
2006年 | 1381篇 |
2005年 | 1249篇 |
2004年 | 1178篇 |
2003年 | 1000篇 |
2002年 | 935篇 |
2001年 | 759篇 |
2000年 | 637篇 |
1999年 | 612篇 |
1998年 | 546篇 |
1997年 | 474篇 |
1996年 | 407篇 |
1995年 | 410篇 |
1994年 | 263篇 |
1993年 | 248篇 |
1992年 | 186篇 |
1991年 | 214篇 |
1990年 | 145篇 |
1989年 | 93篇 |
1988年 | 122篇 |
1987年 | 83篇 |
1986年 | 70篇 |
1985年 | 72篇 |
1984年 | 48篇 |
1983年 | 31篇 |
1982年 | 36篇 |
1981年 | 43篇 |
1980年 | 29篇 |
1979年 | 30篇 |
1978年 | 19篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Andrei‐Florin Albioru 《Mathematische Nachrichten》2019,292(9):1876-1896
The aim of this paper is to establish a well‐posedness result for a boundary value problem of transmission‐type for the standard and generalized Brinkman systems in two Lipschitz domains in , the former being bounded, and the latter, its complement in . As a first step, we establish a well‐posedness result for a transmission problem for the standard Brinkman systems on complementary Lipschitz domains in by making use of the Potential theory developed for such a system. As a second step, we prove our desired result (in L2‐based Sobolev spaces) by using a method based on Fredholm operator theory and the well‐posedness result from the previous step. 相似文献
72.
《Operations Research Letters》2019,47(5):417-420
We analyse the point availability of Gaver’s parallel system supervised by a safety device. For safety reasons, no unit is allowed to operate without supervision. The entire system is attended by two heterogeneous repairmen. Our methodology is based on the theory of sectionally holomorphic functions combined with the notion of dual transforms. As an application we consider Coxian repair time distributions. 相似文献
73.
We consider the chemotaxis‐Navier–Stokes system 1.1-1.4 (Keller–Segel system) in the whole space, which describes the motion of oxygen‐driven bacteria, eukaryotes, in a fluid. We proved the global existence and time decay estimate of solutions to the Cauchy problem 1.1-1.2 in with the small initial data. Moreover, when the fluid motion is described by the Stokes equations, we established the global weak solutions to 1.3-1.4 in with the potential function ? is small and the initial density n0(x) has finite mass. 相似文献
74.
Rong Chen Zhijun Qiao Shouming Zhou 《Mathematical Methods in the Applied Sciences》2019,42(18):6999-7010
Considered herein is a two‐component Novikov equations (called Geng‐Xue system for short) with cubic nonlinearities. The persistence properties and some unique continuation properties of the solutions to the system in weighted Lp spaces are established. Moreover, a wave‐breaking criterion for strong solutions is determined in the lowest Sobolev space by using the localization analysis in the transport equation theory, and we also give a lower bound for the maximal existence time. 相似文献
75.
76.
In this article, we mainly consider the existence problem of a group divisible design GDD of type . We present two recursive constructions for this configuration using candelabra systems and construct explicitly a few small examples admitting given automorphism groups. As an application, several new infinite classes of GDD s of type are produced. Meanwhile a few new infinite families on candelabra quadruple systems with group sizes being odd and stem size greater than one are also obtained. 相似文献
77.
A variety of heterobiaryl compounds have been synthesized by the Suzuki‐Miyaura coupling reactions of heteroaryl halides with potassium aryltrifluoroborates. Pd (OAc)2 was found to be highly efficient for the Suzuki‐Miyaura coupling reactions of various heteroaryl halides with potassium aryltrifluoroborates in aqueous systems, delivering the corresponding heterobiaryl compounds in good to excellent yields. 相似文献
78.
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
79.
In this paper, the existence and multiplicity of positive solutions is established for Schrödinger‐Poisson system of the form where 0 ∈ Ω is a smooth bounded domain in , , and λ > 0 is a real parameter. Combining with the variational method and Nehari manifold method, two positive solutions of the system are obtained. 相似文献
80.
In this paper, we prove the existence and uniqueness of relaxation oscillation cycle of a slow–fast modified Leslie–Gower model via the entry–exit function and geometric singular perturbation theory. Numerical simulations are also carried out to illustrate our theoretical result. 相似文献