全文获取类型
收费全文 | 10961篇 |
免费 | 404篇 |
国内免费 | 62篇 |
专业分类
化学 | 7373篇 |
晶体学 | 60篇 |
力学 | 321篇 |
数学 | 2007篇 |
物理学 | 1666篇 |
出版年
2023年 | 73篇 |
2022年 | 122篇 |
2021年 | 225篇 |
2020年 | 202篇 |
2019年 | 190篇 |
2018年 | 202篇 |
2017年 | 173篇 |
2016年 | 381篇 |
2015年 | 339篇 |
2014年 | 346篇 |
2013年 | 655篇 |
2012年 | 749篇 |
2011年 | 843篇 |
2010年 | 471篇 |
2009年 | 462篇 |
2008年 | 701篇 |
2007年 | 666篇 |
2006年 | 636篇 |
2005年 | 570篇 |
2004年 | 496篇 |
2003年 | 402篇 |
2002年 | 396篇 |
2001年 | 179篇 |
2000年 | 162篇 |
1999年 | 118篇 |
1998年 | 100篇 |
1997年 | 115篇 |
1996年 | 157篇 |
1995年 | 77篇 |
1994年 | 99篇 |
1993年 | 78篇 |
1992年 | 82篇 |
1991年 | 61篇 |
1990年 | 65篇 |
1989年 | 61篇 |
1988年 | 48篇 |
1987年 | 51篇 |
1986年 | 45篇 |
1985年 | 60篇 |
1984年 | 76篇 |
1983年 | 52篇 |
1982年 | 60篇 |
1981年 | 38篇 |
1980年 | 50篇 |
1979年 | 43篇 |
1978年 | 41篇 |
1977年 | 35篇 |
1976年 | 23篇 |
1974年 | 22篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
Antonio Zecca 《International Journal of Theoretical Physics》1995,34(7):1083-1091
A straightforward calculation shows that, in contrast to what happens for the Dirac equation in the Kerr metric, the net current of particles is not conserved in the case of the Dirac equation in the Tolman-Bondi and Robertson-Walker space-times. 相似文献
42.
The thermotropic liquid-crystalline phase behaviour of a homologous set of bis[N-[[4-[4-(alkoxy)benzoyloxy]2-hydroxyphenyl]methylene]alkanamino] copper(II) complexes is examined. New data are reported and taken into account in addition to those previously reported in this Journal. The influence of alkoxy and alkanamine groups on the nature and stability of the mesophase is underlined. As a general trend, with some notable exception, smectic (C type) mesomorphism is favoured by longer alkoxy and alkanamine chains. Data concerning some Pd(II) and Ni(II) homologous complexes are also reported. The mesophase stability (nematic phase) is higher for palladium and nickel complexes than for the copper containing homologues. 相似文献
43.
Various tests have been carried out in order to compare the performances of several methods used to solve the non-symmetric linear systems of equations arising from implicit discretizations of CFD problems, namely the scalar advection-diffusion equation and the compressible Euler equations. The iterative schemes under consideration belong to three families of algorithms: relaxation (Jacobi and Gauss-Seidel), gradient and Newton methods. Two gradient methods have been selected: a Krylov subspace iteration method (GMRES) and a non-symmetric extension of the conjugate gradient method (CGS). Finally, a quasi-Newton method has also been considered (Broyden). The aim of this paper is to provide indications of which appears to be the most adequate method according to the particular circumstances as well as to discuss the implementation aspects of each scheme. 相似文献
44.
Antonio Jimé nez-Melado Claudio H. Morales 《Proceedings of the American Mathematical Society》2006,134(2):501-507
We show a fixed point theorem for condensing mappings under a new condition of the Leray-Schauder type. We call it the Interior Condition. We also discuss examples that demonstrate the independence of these two conditions.
45.
46.
47.
48.
Maria Benedetta Fadda Nicoletta Curreli Raffaello Pompei Antonio Rescigno Augusto Rinaldi Enrico Sanjust 《Applied biochemistry and biotechnology》1994,44(3):263-270
A highly active thermostable β-glucosidase was purified to homogeneity from a strain ofTrichoderma sp. The enzyme was an extracellular glycoprotein and showed hydrolytic activity toward several β-glucosides.
Cellobiose was found to be the substrate of choice for this enzyme. This finding could suggest future technological applications
of the purified protein. 相似文献
49.
This paper focuses on a new property for bankruptcy rules, calledsustainability, which requires that the agents with small enough claims be fully reimbursed. We show that the constrained equal-awards rule is the only rule that satisfies path independence and sustainability. Exploiting duality relations, we also provide a characterization of the constrained equal-losses rule, as the only one that satisfies composition and independence of residual claims (the dual property of sustainability). 相似文献
50.
Scopo del lavoro è di studiare la stabilità asintotica per le soluzioni di problemi di evoluzione astratti. Si considerano
operatori differenziali quali ilp-Laplaciano, e il poliarmonico, termini smorzanti e fortemente smorzanti, potenziali di richiamo o di sorgente.
相似文献