全文获取类型
收费全文 | 6200篇 |
免费 | 684篇 |
国内免费 | 628篇 |
专业分类
化学 | 1551篇 |
晶体学 | 8篇 |
力学 | 487篇 |
综合类 | 238篇 |
数学 | 3240篇 |
物理学 | 1988篇 |
出版年
2024年 | 15篇 |
2023年 | 78篇 |
2022年 | 210篇 |
2021年 | 286篇 |
2020年 | 198篇 |
2019年 | 174篇 |
2018年 | 129篇 |
2017年 | 222篇 |
2016年 | 288篇 |
2015年 | 214篇 |
2014年 | 352篇 |
2013年 | 401篇 |
2012年 | 372篇 |
2011年 | 355篇 |
2010年 | 276篇 |
2009年 | 387篇 |
2008年 | 404篇 |
2007年 | 379篇 |
2006年 | 370篇 |
2005年 | 326篇 |
2004年 | 259篇 |
2003年 | 245篇 |
2002年 | 217篇 |
2001年 | 183篇 |
2000年 | 190篇 |
1999年 | 139篇 |
1998年 | 137篇 |
1997年 | 125篇 |
1996年 | 103篇 |
1995年 | 60篇 |
1994年 | 77篇 |
1993年 | 41篇 |
1992年 | 39篇 |
1991年 | 33篇 |
1990年 | 28篇 |
1989年 | 28篇 |
1988年 | 24篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 3篇 |
排序方式: 共有7512条查询结果,搜索用时 312 毫秒
91.
It is proved that the center of an automorphism group Aut(FVL2) of a free vector lattice FVL2 on a set of two free generators is isomorphic to a multiplicative group of positive reals. It is shown that the free vector lattice FVL2 has an isomorphic representation by continuous piecewise linear functions of the real line; as a consequence, the ideal lattice and the root system for rectifying ideals in FVL2 are amply described. Similar results are obtained for a free vector lattice FVL2
Q
2 generated by two elements over a field of rational numbers. 相似文献
92.
Qun Luo 《Journal of Global Optimization》2006,34(4):589-595
In the paper, by using Ky Fan’s section theorem, we obtain an existence theorem for vector equilibrium problems. Motivated
by the ideas of Kinoshita and McLennan, we introduce the concept of the essential component of the solution set for vector
equilibrium problems, and we prove that there exists at least one essential component of the solution set for every vector
equilibrium problem satisfying some conditions.
Research was partially supported by the Natural Science Foundation of Guangdong Province, P. R. China. 相似文献
93.
Wanpracha Art Chaovalitwongse Oleg A. Prokopyev Panos M. Pardalos 《Annals of Operations Research》2006,148(1):227-250
Epilepsy is among the most common brain disorders. Approximately 25–30% of epilepsy patients remain unresponsive to anti-epileptic
drug treatment, which is the standard therapy for epilepsy. In this study, we apply optimization-based data mining techniques
to classify the brain's normal and epilepsy activity using intracranial electroencephalogram (EEG), which is a tool for evaluating
the physiological state of the brain. A statistical cross validation and support vector machines were implemented to classify
the brain's normal and abnormal activities. The results of this study indicate that it may be possible to design and develop
efficient seizure warning algorithms for diagnostic and therapeutic purposes.
Research was partially supported by the Rutgers Research Council grant-202018, the NSF grants DBI-980821, CCF-0546574, IIS-0611998,
and NIH grant R01-NS-39687-01A1. 相似文献
94.
We give a self‐contained proof of the preservation theorem for proper countable support iterations known as “tools‐preservation”, “Case A” or “first preservation theorem” in the literature. We do not assume that the forcings add reals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
95.
H. Eduardo Roman 《Journal of statistical physics》1990,58(1-2):375-382
Extensive Monte Carlo simulations of theant-in-the-labyrinth problem on randomL* L* L simple cubic lattices are performed, forL up to 960 on a CRAY-YMP supercomputer. The exponentk for the rms displacementr witht inrt
k
is found to bek=0.190±0.003. As a second approach, large percolation clusters with chemical shells up to 300 are generated on a simple cubic lattice at criticality. The diffusion equation is then solved by using the exact enumeration technique. The corresponding critical exponentd
w
is found to be 1/d
w
=0.250±0.003.On leave from I. Institut für Theoretische für Physik, Universität Hamburg, D-2000 Hamburg, Federal Republic of Germany. 相似文献
96.
Let (X, , ) be a finite atomless measure space,L a convex subfamily of , andY andZ locally convex Hausdorff topological vector spaces which are ordered by the conesC andD, respectively. LetF:LY beC-convex andG:LZ beD-convex set functions. Consider the following optimization problem (P): minimizeF(), subject to L andG()
D
. The paper generalizes the Moreau-Rockafellar theorem with set functions. By applying this theorem, a Kuhn-Tucker type optimality condition and a Fritz John type optimality condition for problem (P) are established. The duality theorem for problem (P) is also studied.This work was partially supported by National Science Council, Taipei, Taiwan. This paper was written while the first author was visiting at the University of Iowa, 1987-88.The authors would like to express their gratitude to the two anonymous referees for their valuable comments. Also, they would like to thank Professor P. L. Yu for his encouragement and suggestions which improved the material presented here considerably. 相似文献
97.
98.
The construction of an expert-like system for machine scheduling called SCHEDULE is presented. Essential parts of SCHEDULE were developed by students in a laboratory course Operations Research on Microcomputers at the University of Karlsruhe, Germany. SCHEDULE consists of the components data base, knowledge base, inference engine, explanation facility, dialog component, and knowledge acquisition component. The knowledge base contains an algorithm base for solving different types of scheduling problems. To establish the rules of the knowledge base the well-known three-field classification of deterministic machine scheduling problems and the concept of the reduction digraph are exploited. Experiences gained during building and demonstrating SCHEDULE are reported. 相似文献
99.
100.
采用固相反应法合成A缺位的(La0.8Sr0.2)0.95MnO3(LSM95)作为阴极材料,Zr0.9Sc0.1SO1.95(SSZ)商业粉体作为电解质材料,溶胶-凝胶法合成的La0.8Sr0.2Cr0.5Mn0.5O3-(LSCrM)作为阳极电催化材料,利用流延、共烧结及浸渍法得到结构为LSCrM-CeO2|SSZ|3YSZ-LSM95的阴极支撑型固体氧化物燃料电池,分别在氢气气氛和甲烷气氛中进行电化学性能测试. 结果表明,浸渍0.11 g·cm -2 CeO2的LSCrM-CeO2|SSZ|3YSZ-LSM95单电池在以CH4为燃料时,600、650、700、750和800 oC下的功率密度分别为1.68、4.70、12.40、28.08和54.78 mW·cm -2,表现出一定的电化学性能和较好的稳定性. 相似文献