全文获取类型
收费全文 | 6376篇 |
免费 | 1259篇 |
国内免费 | 823篇 |
专业分类
化学 | 2634篇 |
晶体学 | 98篇 |
力学 | 347篇 |
综合类 | 50篇 |
数学 | 1499篇 |
物理学 | 3830篇 |
出版年
2024年 | 13篇 |
2023年 | 77篇 |
2022年 | 168篇 |
2021年 | 145篇 |
2020年 | 178篇 |
2019年 | 164篇 |
2018年 | 158篇 |
2017年 | 169篇 |
2016年 | 208篇 |
2015年 | 192篇 |
2014年 | 295篇 |
2013年 | 508篇 |
2012年 | 351篇 |
2011年 | 362篇 |
2010年 | 363篇 |
2009年 | 457篇 |
2008年 | 455篇 |
2007年 | 466篇 |
2006年 | 443篇 |
2005年 | 419篇 |
2004年 | 322篇 |
2003年 | 326篇 |
2002年 | 346篇 |
2001年 | 265篇 |
2000年 | 252篇 |
1999年 | 230篇 |
1998年 | 196篇 |
1997年 | 150篇 |
1996年 | 107篇 |
1995年 | 87篇 |
1994年 | 84篇 |
1993年 | 56篇 |
1992年 | 52篇 |
1991年 | 50篇 |
1990年 | 36篇 |
1989年 | 42篇 |
1988年 | 41篇 |
1987年 | 29篇 |
1986年 | 33篇 |
1985年 | 33篇 |
1984年 | 20篇 |
1983年 | 9篇 |
1982年 | 21篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1972年 | 5篇 |
排序方式: 共有8458条查询结果,搜索用时 15 毫秒
61.
D. Sasireka E. Palaniyandi K. Iyakutti 《International journal of quantum chemistry》2004,99(3):142-152
Local lattice relaxation of substitutional donors in silicon investigated using self‐consistent multiple scattering Xα (MSXα) method within the framework of the standard muffin‐tin potential approximation is extended to substitutional donors in germanium and substitutional acceptors in both silicon and germanium. Incorporating the effect of lattice relaxation surrounding the impurity makes the model suitable for both shallow and deep levels. Chemical trends of some aspects of impurity states, such as local lattice relaxation and charge transfer, of the impurities both in silicon and germanium are inferred. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
62.
Alpeshkumar K. Malde Santosh A. Khedkar Evans C. Coutinho 《Journal of Physical Organic Chemistry》2007,20(2):151-160
Modification of peptides to produce peptidomimetics is of great interest, with the aim of designing potent, selective, and metabolically stable analogs having certain conformational properties. Organoboranes have been reported in the literature with a wide range of therapeutic applications. One of the therapeutically important class of molecules is amine‐carboxyboranes derived from amino acids by replacement of the Cα atom of an amino acid/peptide by boron. The conformational preferences of these peptides, with respect to backbone ω, ?, and ψ torsion angles, have been investigated by theoretical calculations. The amide bond in these molecules has the same geometry in the ground and transition states as the natural peptides. However, the boron isosteres of glycine and alanine peptides are less structured than their natural derivatives, but are distinguished by structures with a positive value for the ? angle, which is normally disfavored for natural peptides. This property could be used to build peptides with a geometry not usually seen in natural peptides. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
63.
首先通过集代数得到了Stone代数的表示定理,然后证明了每一个Stone代数均嵌入到某个集合X上的一个Stone映射类S中. 相似文献
64.
M. V. Semenova 《Siberian Mathematical Journal》2007,48(4):718-732
We prove that the class of finite lattices embeddable into the subsemilattice lattices of semilattices which are (n-ary) trees can be axiomatized by identities within the class of finite lattices, whence it forms a pseudovariety. 相似文献
65.
We prove that directly reducible lattices and selfdual subdirectly irreducible lattices of locally finite length are determined by their sublattice-lattices. As a corollary we obtain that splitting varieties are closed under the isomorphism of sublattice-lattices iff they are selfdual. A class of selfdual non-closed varieties is given too. 相似文献
66.
Protein Conformation of a Lattice Model Using Tabu Search 总被引:1,自引:0,他引:1
We apply tabu search techniques to the problem of determining the optimal configuration of a chain of protein sequences on a cubic lattice. The problem under study is difficult to solve because of the large number of possible conformations and enormous amount of computations required. Tabu search is an iterative heuristic procedure which has been shown to be a remarkably effective method for solving combinatorial optimization problems. In this paper, an algorithm is designed for the cubic lattice model using tabu search. The algorithm has been tested on a chain of 27 monomers. Computational results show that our method outperforms previously reported approaches for the same model. 相似文献
67.
Average Atom Model in Hot Plasmas 总被引:4,自引:2,他引:2
Average Atom Model in Hot PlasmasAverageAtomModelinHotPlasmas¥YuanJianhui;SunYongsheng;ZhengShaotang(InstituteofAppliedPhysic... 相似文献
68.
C S Rajan 《Proceedings Mathematical Sciences》1994,104(2):389-395
LetG be a connected complex semisimple Lie group. Let Γ be a cocompact lattice inG. In this paper, we show that whenG isSL
2(C), nontrivial deformations of the canonical complex structure onX exist if and only if the first Betti number of the lattice Γ is non-zero. It may be remarked that for a wide class of arithmetic
groups Γ, one can find a subgroup Γ′ of finite index in Γ, such that Γ′/[Γ′,Γ′] is finite (it is a conjecture of Thurston
that this is true for all cocompact lattices inSL(2, C)).
We also show thatG acts trivially on the coherent cohomology groupsH
i(Γ/G, O) for anyi≥0. 相似文献
69.
采用无规相近似(RPA)方法,用空心图作为试探波函数,利用Feymann?Hellman定理计算七阶2?+?1维SU(2?)格点规范场的胶球质量,在弱耦合区1/g2?=1.0?–?1.8胶球质量表现出良好的标度行为,基本趋于常数(m/e2?≈1.2?0±0?.0?1)?. 相似文献
70.
多线性Calderón-Zygmund算子的加权有界性 总被引:2,自引:0,他引:2
建立了多线性Calderón-Zygmund算子在比幂权空间更一般的Herz空间和Herz型Hardy空间上的有界性.作为推论,得到了该算子的幂权估计.在这些幂权估计中,权指标可以突破Ap权的指标限制,显示出和经典Calderón-Zygmund算子本质的区别. 相似文献