全文获取类型
收费全文 | 17533篇 |
免费 | 427篇 |
国内免费 | 320篇 |
专业分类
化学 | 1217篇 |
晶体学 | 42篇 |
力学 | 207篇 |
综合类 | 20篇 |
数学 | 15510篇 |
物理学 | 1284篇 |
出版年
2023年 | 24篇 |
2022年 | 40篇 |
2021年 | 32篇 |
2020年 | 65篇 |
2019年 | 492篇 |
2018年 | 592篇 |
2017年 | 280篇 |
2016年 | 171篇 |
2015年 | 203篇 |
2014年 | 561篇 |
2013年 | 1159篇 |
2012年 | 643篇 |
2011年 | 1123篇 |
2010年 | 980篇 |
2009年 | 1265篇 |
2008年 | 1339篇 |
2007年 | 1289篇 |
2006年 | 1022篇 |
2005年 | 658篇 |
2004年 | 553篇 |
2003年 | 512篇 |
2002年 | 367篇 |
2001年 | 371篇 |
2000年 | 362篇 |
1999年 | 429篇 |
1998年 | 376篇 |
1997年 | 319篇 |
1996年 | 411篇 |
1995年 | 411篇 |
1994年 | 396篇 |
1993年 | 317篇 |
1992年 | 197篇 |
1991年 | 104篇 |
1990年 | 75篇 |
1989年 | 92篇 |
1988年 | 71篇 |
1987年 | 59篇 |
1986年 | 60篇 |
1985年 | 108篇 |
1984年 | 115篇 |
1983年 | 84篇 |
1982年 | 113篇 |
1981年 | 98篇 |
1980年 | 67篇 |
1979年 | 55篇 |
1978年 | 62篇 |
1977年 | 52篇 |
1976年 | 40篇 |
1975年 | 22篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
David Swanson William P. Ziemer 《Calculus of Variations and Partial Differential Equations》2002,14(1):69-84
Let be a connected open set, . We give a sufficient condition for a mapping , , to have the property that sgn is almost everywhere of one sign. Following the work of Müller, Spector, and Tang [MST], we give an application of our results
to the theory of non-linear elasticity.
Received: 13 October 2000 / Accepted: 23 January 2001 / Published online: 4 May 2001 相似文献
102.
New derivation results for integrands and multifunctions via the Lipschitzean approximations are obtained. Applications to multivalued differential equations on closed convex sets are presented. 相似文献
103.
A. Louise Perkins 《BIT Numerical Mathematics》1992,32(4):598-608
The choice of data structures influences the parallelization, efficiency and the manageability of a mesh refinement program. We introduce a mixed directed-undirected graph that combines both communication and scheduling needs. An inverted index is maintained for the directed graph to improve code performance and readability.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. 相似文献
104.
E. Alfinito M. Leo R. A. Leo M. Palese G. Soliani 《Letters in Mathematical Physics》1994,32(3):241-248
The Estabrook-Wahlquist prolongation method is applied to the (compact and noncompact) continuous isotropic Heisenberg model in 1 + 1 dimensions. Using a special realization (an algebra of the Kac-Moody type) of the arising incomplete prolongation Lie algebra, a whole family of nonlinear field equations containing the original Heisenberg system is generated. 相似文献
105.
Ginette Ratovo Jean‐Pierre Souchard Pascale Urizzi Yvon Coulais Franoise Nepveu Etienne Hollande 《应用有机金属化学》2004,18(1):1-8
Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, 111In–L–LDL and 153Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of 111In–L–LDL and 153Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (111In citrate and 153Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as 111In or 153Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that 111In–L–LDL and 153Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with 153Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
106.
107.
Janusz Mierczyński Wenxian Shen Xiao-Qiang Zhao 《Journal of Differential Equations》2004,204(2):471-510
The purpose of this paper is to investigate uniform persistence for nonautonomous and random parabolic Kolmogorov systems via the skew-product semiflows approach. It is first shown that the uniform persistence of the skew-product semiflow associated with a nonautonomous (random) parabolic Kolmogorov system implies that of the system. Various sufficient conditions in terms of the so-called unsaturatedness and/or Lyapunov exponents for uniform persistence of the skew-product semiflows are then provided. Among others, it is shown that if the associated skew-product semiflow has a global attractor and its restriction to the boundary of the state space has a Morse decomposition which is unsaturated or whose external Lyapunov exponents are positive, then it is uniformly persistent. More specific conditions are discussed for uniform persistence in n-species, particularly 3-species, random competitive systems. 相似文献
108.
Jean Dolbeault Maria J Esteban Michael Loss Luis Vega 《Journal of Functional Analysis》2004,216(1):1-21
We prove some sharp Hardy-type inequalities related to the Dirac operator by elementary, direct methods. Some of these inequalities have been obtained previously using spectral information about the Dirac-Coulomb operator. Our results are stated under optimal conditions on the asymptotics of the potentials near zero and near infinity. 相似文献
109.
Xicheng Zhang 《Bulletin des Sciences Mathématiques》2004,128(5):333-340
In this paper we give a representation formula for the heat semigroup on adapted vector fields by the horizontal lift of Ornstein-Uhlenbeck process over Riemannian path space. 相似文献
110.
Baisheng Yan 《Bulletin des Sciences Mathématiques》2003,127(6):467-483
We study the solvability of special vectorial Hamilton-Jacobi systems of the form F(Du(x))=0 in a Sobolev space. In this paper we establish the general existence theorems for certain Dirichlet problems using suitable approximation schemes called W1,p-reduction principles that generalize the similar reduction principle for Lipschitz solutions. Our approach, to a large extent, unifies the existing methods for the existence results of the special Hamilton-Jacobi systems under study. The method relies on a new Baire's category argument concerning the residual continuity of a Baire-one function. Some sufficient conditions for W1,p-reduction are also given along with certain generalization of some known results and a specific application to the boundary value problem for special weakly quasiregular mappings. 相似文献