全文获取类型
收费全文 | 1001篇 |
免费 | 20篇 |
国内免费 | 99篇 |
专业分类
化学 | 195篇 |
晶体学 | 3篇 |
力学 | 24篇 |
综合类 | 8篇 |
数学 | 799篇 |
物理学 | 91篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 11篇 |
2020年 | 28篇 |
2019年 | 23篇 |
2018年 | 23篇 |
2017年 | 20篇 |
2016年 | 17篇 |
2015年 | 22篇 |
2014年 | 40篇 |
2013年 | 90篇 |
2012年 | 32篇 |
2011年 | 53篇 |
2010年 | 30篇 |
2009年 | 69篇 |
2008年 | 83篇 |
2007年 | 92篇 |
2006年 | 63篇 |
2005年 | 40篇 |
2004年 | 52篇 |
2003年 | 39篇 |
2002年 | 38篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 34篇 |
1998年 | 30篇 |
1997年 | 21篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 22篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1120条查询结果,搜索用时 15 毫秒
991.
We show that the Fibered Isomorphism Conjecture of T. Farrell and L. Jones holds for various mapping class groups. In many cases, we explicitly calculate the lower algebraic K-groups, showing that they do not always vanish. 相似文献
992.
In one of our recent papers, the associative and the Lie algebras of Weyl typeA[D]=A⊗F[D] were defined and studied, whereA is a commutative associative algebra with an identity element over a field F of any characteristic, and F[D] is the polynomial algebra of a commutative derivation subalgebraD ofA. In the present paper, a class of the above associative and Lie algebrasA[D] with F being a field of characteristic 0,D consisting of locally finite but not locally nilpotent derivations ofA, are studied. The isomorphism classes and automorphism groups of these associative and Lie algebras are determined 相似文献
993.
本文继续[1,2]关于分布式环网的研究。我们建立了N阶双连环网的同构定理,并证明了同构的双连环网有相等的直径。因此,所有的N阶双连环网可以按同构分类。 相似文献
994.
995.
This paper presents a method for modifying anLU factorization of a matrixA when a Simplex update is performed onA. At each stage of the algorithm, two options are allowed, and in one of these a row permutation ofL is made so that theLU structure is always maintained. The expanding file of operators used in other methods is not required. The result, of an
error analysis is presented in which the error is bounded by the growth in the partial sums ofLU. Various pivotal strategies which minimize a growth bound are discussed and an example is given in which the worst case for
growth occurs repeatedly. Numerical results from experiments on ill-conditioned problems show no tendency for error growth. 相似文献
996.
997.
Nonexistence of stable currents 总被引:1,自引:0,他引:1
Qing-Ming Cheng 《Annals of Global Analysis and Geometry》1995,13(2):197-205
In this paper, we investigate nonexistence of stable integral currents in a compact hypersurface with positive Ricci curvature in a Euclidean spaceR
m+1 and a vanishing theorem concerning the homology group is obtained.The project was supported by NNSFC, FECC and CPSF 相似文献
998.
Takeaki Iwamoto 《Journal of organometallic chemistry》2004,689(8):1337-1341
The results of the thermolysis of 1:2 adducts of stable group-14 element divalent compounds [R2M:, R2=1,1,4,4-tetrakis(trimethylsilyl)butane-1,4-diyl; 1b, M=Ge; 1c, M=Sn] to TEMPO radical are discussed in detail. Whereas the thermal reactions of the 1:2 adducts [R2M(OR′)2, R′=2,2,6,6-tetramethylpiperidin-N-yl; 3b, M=Ge; 3c, M=Sn] are understood to proceed by the initial homolysis of an M-O bond to give the corresponding aminoxy-substituted group-14 element radicals [R2(R′O)M; 2b, M=Ge; 2c, M=Sn] and TEMPO, the subsequent reactions of 2b and 2c were remarkably different to each other; 2b favors the N-O bond fission (path b) to give the corresponding germanone, while 2c prefers the M-O bond fission (path a) to give stannylene (1c). In combining with our previous results for aminoxysilyl radical (2a) [R2(R′O)Si], the origin of the remarkable differences in the reactivity among group-14 element radicals 2a-2c is discussed on the basis of the theoretical calculations for model reactions.Improved syntheses of the precursor dichlorogermane and dichlorostannane of germylene (1b) and stannylene (1c), respectively, are described in Section 3. 相似文献
999.
Summary Because methylmalonic acid (MMA) accumulates in the body fluids of patients suffering from inherited metabolic disorders involving its pathway, the quantitation of this metabolite is not only fundamental to diagnosis but is also important in the follow-up of affected patients under treatment.We describe the method set up and used in our laboratory for the measurement of MMA in body fluids and propose its application to plasma as the reference method for the biochemical diagnosis and follow-up of methylmalonic acidaemias. 相似文献
1000.
Maximum common subgraph isomorphism algorithms for the matching of chemical structures 总被引:1,自引:0,他引:1
The maximum common subgraph (MCS) problem has become increasingly important in those aspects of chemoinformatics that involve the matching of 2D or 3D chemical structures. This paper provides a classification and a review of the many MCS algorithms, both exact and approximate, that have been described in the literature, and makes recommendations regarding their applicability to typical chemoinformatics tasks. 相似文献