全文获取类型
收费全文 | 9323篇 |
免费 | 1104篇 |
国内免费 | 657篇 |
专业分类
化学 | 1155篇 |
晶体学 | 35篇 |
力学 | 1082篇 |
综合类 | 142篇 |
数学 | 4709篇 |
物理学 | 3961篇 |
出版年
2024年 | 31篇 |
2023年 | 87篇 |
2022年 | 491篇 |
2021年 | 488篇 |
2020年 | 301篇 |
2019年 | 230篇 |
2018年 | 270篇 |
2017年 | 243篇 |
2016年 | 305篇 |
2015年 | 256篇 |
2014年 | 417篇 |
2013年 | 598篇 |
2012年 | 383篇 |
2011年 | 473篇 |
2010年 | 437篇 |
2009年 | 512篇 |
2008年 | 550篇 |
2007年 | 527篇 |
2006年 | 509篇 |
2005年 | 473篇 |
2004年 | 350篇 |
2003年 | 406篇 |
2002年 | 366篇 |
2001年 | 277篇 |
2000年 | 245篇 |
1999年 | 249篇 |
1998年 | 181篇 |
1997年 | 205篇 |
1996年 | 135篇 |
1995年 | 113篇 |
1994年 | 129篇 |
1993年 | 98篇 |
1992年 | 99篇 |
1991年 | 93篇 |
1990年 | 61篇 |
1989年 | 51篇 |
1988年 | 55篇 |
1987年 | 43篇 |
1986年 | 33篇 |
1985年 | 45篇 |
1984年 | 42篇 |
1983年 | 13篇 |
1982年 | 37篇 |
1981年 | 27篇 |
1980年 | 30篇 |
1979年 | 33篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Antonio Vitolo 《Journal of Differential Equations》2003,194(1):166-184
This paper is concerned with the maximum principle for second-order linear elliptic equations in a wide generality. By means of a geometric condition previously stressed by Berestycki-Nirenberg-Varadhan, Cabré was very able to improve the classical ABP estimate obtaining the maximum principle also in unbounded domains, such as infinite strips and open connected cones with closure different from the whole space. Now we introduce a new geometric condition that extends the result to a more general class of domains including the complements of hypersurfaces, as for instance the cut plane. The methods developed here allow us to deal with complete second-order equations, where the admissible first-order term, forced to be zero in a preceding result with Cafagna, depends on the geometry of the domain. 相似文献
32.
Guang-hua DONG~ Yan-pei LIU Department of Mathematics School of Science Beijing Jiaotong University Beijing China 《中国科学A辑(英文版)》2007,50(11):1563-1570
In this paper,we provide a new class of up-embeddable graphs,and obtain a tight lower bound on the maximum genus of a class of 2-connected pseudographs of diameter 2 and of a class of diameter 4 multi-graphs.This extends a result of Skoviera. 相似文献
33.
P. Q. Khanh 《Journal of Optimization Theory and Applications》1995,87(2):359-378
We prove the Kuhn-Tucker sufficient optimality condition, the Wolfe duality, and a modified Mond-Weir duality for vector optimization problems involving various types of invex-convexlike functions. The class of such functins contains many known generalized convex functions. As applications, we demonstrate that, under invex-convexlikeness assumptions, the Pontryagin maximum principle is a sufficient optimality condition for cooperative differential games. The Wolfe duality is established for these games.The author is indebted to the referees and Professor W. Stadler for valuable remarks and comments, which have been used to revise considerably the paper. 相似文献
34.
35.
对数似然比与整值随机变量序列的一类强律 总被引:2,自引:0,他引:2
本文引进对数似然比作为整值随机变量序列相对于服从几何分布的独立随机变量序列的偏差的一种度量,并通过限制对数似然比给出了样本空间的一个子集.在此子集上得到了一类用不等式表示的强律,其中包含整值随机变量序列与相对熵密度及几何分布的熵函数有关的若干极限性质. 相似文献
36.
Detailed pH-dependent steady state and picosecond time-resolved tryptophan fluorescence studies on thiocyanate and azide complexes
of horseradish peroxidase have been carried out. The fluorescence decay of the single tryptophan in these species was fitted
to a discrete three exponential model. Maximum entropy method analysis also gave three distinct regions of lifetime distributions.
The fast subnanosecond lifetime component was found to have > 97% amplitude contribution while other two longer lifetime components
have small contributions. Small contributions from the nanosecond lifetime components possibly arise from apoprotein impurity
or some small amount of disordered heme conformer of the protein. pH dependence of the fast picosecond lifetime components
was found to show a systematic behavior which has been interpreted in the light of obligatory conformation change associated
with activation of the enzyme at low pH. 相似文献
37.
38.
39.
事件空间中二阶非Четаев型非完整系统的守恒律 总被引:1,自引:1,他引:0
研究事件空间中二阶非чeTaeB型非完整系统的守恒律。提出事件空间中的Jourdain原理,引入事件空间中的Jorudain生成元,给出无限小变换下的Jourdain原理的不变性条件。在一定条件下得到事件空间中系统的守恒律。并举例说明结果的应用。 相似文献
40.
K. Holmåker 《Journal of Optimization Theory and Applications》1991,71(2):205-235
Some optimization problems concerning a substrate in a fluid are considered. The concentration of the substrate is affected by diffusion, convection, and elimination by enzymes, and the problem is to find the optimal distribution of enzymes. In this paper, the rate of elimination and the transmission coefficient are optimized. Mathematically, these problems are optimal control problems, and they are analyzed by means of Pontryagin's maximum principle. 相似文献