全文获取类型
收费全文 | 224884篇 |
免费 | 1882篇 |
国内免费 | 782篇 |
专业分类
化学 | 104958篇 |
晶体学 | 3145篇 |
力学 | 12718篇 |
综合类 | 3篇 |
数学 | 45139篇 |
物理学 | 61585篇 |
出版年
2021年 | 1085篇 |
2020年 | 1219篇 |
2019年 | 1293篇 |
2018年 | 11926篇 |
2017年 | 11794篇 |
2016年 | 8552篇 |
2015年 | 2436篇 |
2014年 | 2694篇 |
2013年 | 6439篇 |
2012年 | 8610篇 |
2011年 | 16334篇 |
2010年 | 9756篇 |
2009年 | 10192篇 |
2008年 | 12247篇 |
2007年 | 14141篇 |
2006年 | 5662篇 |
2005年 | 6266篇 |
2004年 | 6001篇 |
2003年 | 6063篇 |
2002年 | 5043篇 |
2001年 | 5808篇 |
2000年 | 4302篇 |
1999年 | 3235篇 |
1998年 | 2316篇 |
1997年 | 2369篇 |
1996年 | 2284篇 |
1995年 | 2063篇 |
1994年 | 2014篇 |
1993年 | 1851篇 |
1992年 | 2292篇 |
1991年 | 2396篇 |
1990年 | 2214篇 |
1989年 | 2177篇 |
1988年 | 2158篇 |
1987年 | 2159篇 |
1986年 | 1987篇 |
1985年 | 2442篇 |
1984年 | 2458篇 |
1983年 | 1962篇 |
1982年 | 1968篇 |
1981年 | 1803篇 |
1980年 | 1791篇 |
1979年 | 2076篇 |
1978年 | 2141篇 |
1977年 | 2074篇 |
1976年 | 1997篇 |
1975年 | 1880篇 |
1974年 | 1859篇 |
1973年 | 1903篇 |
1972年 | 1252篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
V. B. Sokolov A. N. Chekhlov T. A. Epishina I. V. Martynov 《Russian Chemical Bulletin》1992,41(2):236-240
The O-(arylcarbamoyl)butyrhydroximoyl chlorides were synthesized, and the x-ray structural analysis (XSA) of one of them — O-(o-tolylcarbamoyl)butyrhydroximoyl chloride — was performed. It was established from the data of the XSA and the PMR spectra that all synthesized compounds are the Z isomers.Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 315–319, February, 1992. 相似文献
992.
Lai-Jiu Lin 《Journal of Global Optimization》2007,38(1):21-39
In this paper, we study an existence theorem of systems of generalized quasivariational inclusions problem. By this result,
we establish the existence theorems of solutions of systems of generalized equations, systems of generalized vector quasiequilibrium
problem, collective variational fixed point, systems of generalized quasiloose saddle point, systems of minimax theorem, mathematical
program with systems of variational inclusions constraints, mathematical program with systems of equilibrium constraints and
systems of bilevel problem and semi-infinite problem with systems of equilibrium problem constraints.
This research was supported by the National Science Council of the Republic of China. 相似文献
993.
Roberto Stasi 《Potential Analysis》2007,26(3):213-224
In this paper we prove the validity of the Maximum Principle for some class of elliptic and parabolic equations of diffusion
type in infinite dimension. The main tools are Asplund’s theorem and Preiss’ theorem on differentiability of Lipschitz functions
in Banach space.
相似文献
994.
The fixed point property for multivalued nonexpansive mappings 总被引:1,自引:0,他引:1
T. Domínguez Benavides 《Journal of Mathematical Analysis and Applications》2007,328(2):1471-1483
We show some properties concerning geometrical constants of Banach spaces which imply the existence of fixed points for multivalued nonexpansive mappings and we study the relationship between these properties. 相似文献
995.
We prove some basic properties of Donaldson’s flow of surfaces in a hyperkähler 4-manifold. When the initial submanifold is symplectic with respect to one Kähler form and Lagrangian with respect to another, we show that certain kinds of singularities cannot form, and we prove a convergence result under a condition related to one considered by M.-T. Wang for the mean curvature flow. 相似文献
996.
Consider a semigroup generated by matrices associated with an edge-coloring of a strongly connected, aperiodic digraph. We
call the semigroup Lie-solvable if the Lie algebra generated by its elements is solvable. We show that if the semigroup is
Lie-solvable then its kernel is a right group. Next, we study the Lie algebra generated by the kernel. Lie algebras generated
by two idempotents are analyzed in detail. We find that these have homomorphic images that are generalized quaternion algebras.
We show that if the kernel is not a direct product, then the Lie algebra generated by the kernel is not solvable by describing
the structure of these algebras. Finally, we discuss an infinite class of examples that are shown to always produce strongly
connected aperiodic digraphs having kernels that are not right groups. 相似文献
997.
998.
The interaction between gene activation and cellular activity has recently emerged as a critical aspect of brain behavior, but the dynamics of networks incorporating these interactions are poorly understood. An interesting phenomena arises when the genetic activation oscillates endogenously and a network of such cells synchronize to a coherent rhythm, such as is the case with the suprachiasmatic nucleus. To explain this synchronization, we propose a model in which a mRNA/protein expression cycle drives neurons electrical activity, and synaptic activation shifts the phase of the protein rhythm. Using lattice networks, we demonstrate that these interactions are sufficient to generate coherent oscillation. © 2006 Wiley Periodicals, Inc. Complexity 12: 67–72, 2006 相似文献
999.
V. V. Platonov A. A. Khadartsev A. Yu. Shvykin D. V. Prokopchenkov V. A. Proskuryakov T. V. Chestnova 《Russian Journal of Applied Chemistry》2006,79(10):1581-1587
The organic matter of schungite rock from the Zazhogino Deposit of Karelian Transonega region was extracted in the sequential mode. The extract composition was determined by several modern physicochemical methods. 相似文献
1000.
S. A. Andronati A. A. Krys’ko B. M. Chugunov T. A. Kabanova A. G. Artemenko 《Russian Journal of Organic Chemistry》2006,42(8):1174-1182
A new series of RGDF mimetics, derivatives of 4-(isoindolin-5-yl)amino-4-oxobutanoic acid, was synthesized. The compounds obtained inhibit efficiently the thrombocytes aggregation in experiments in vitro; their biological targets are fibrinogen receptors. The antiaggregatory activity and the affinity correlate with the hydrophobicity of the compounds. 相似文献