全文获取类型
收费全文 | 14319篇 |
免费 | 1489篇 |
国内免费 | 1497篇 |
专业分类
化学 | 6219篇 |
晶体学 | 88篇 |
力学 | 1261篇 |
综合类 | 243篇 |
数学 | 6269篇 |
物理学 | 3225篇 |
出版年
2024年 | 28篇 |
2023年 | 145篇 |
2022年 | 227篇 |
2021年 | 324篇 |
2020年 | 465篇 |
2019年 | 418篇 |
2018年 | 374篇 |
2017年 | 475篇 |
2016年 | 638篇 |
2015年 | 447篇 |
2014年 | 702篇 |
2013年 | 1378篇 |
2012年 | 719篇 |
2011年 | 868篇 |
2010年 | 792篇 |
2009年 | 849篇 |
2008年 | 866篇 |
2007年 | 919篇 |
2006年 | 873篇 |
2005年 | 772篇 |
2004年 | 699篇 |
2003年 | 653篇 |
2002年 | 558篇 |
2001年 | 438篇 |
2000年 | 399篇 |
1999年 | 344篇 |
1998年 | 307篇 |
1997年 | 264篇 |
1996年 | 236篇 |
1995年 | 196篇 |
1994年 | 154篇 |
1993年 | 124篇 |
1992年 | 106篇 |
1991年 | 103篇 |
1990年 | 57篇 |
1989年 | 64篇 |
1988年 | 49篇 |
1987年 | 30篇 |
1986年 | 34篇 |
1985年 | 33篇 |
1984年 | 31篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 7篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Jerzy Cioslowski 《Theoretical chemistry accounts》1992,81(4-5):319-327
Summary A new index, called the differential density matrix overlap (DDMO), is proposed for assessment of the electron correlation effects in atoms and molecules. DDMO can be easily calculated as the negative value of the correlation energy derivative with respect to the relative position of the occupied and virtual orbitals. DDMO is transparent to physical interpretation. It can serve as a tool for analyzing the accuracy of approximate electron correlation methods and the validity of the Hartree-Fock wavefunction as the zeroth-order approximation. The properties of DDMO are discussed using test calculations on 11 atoms and molecules as an example. 相似文献
102.
蒋忠樟 《数学的实践与认识》2007,37(15):174-179
实对称正定矩阵的复合矩阵正定性的研究已有结论,但对于一般意义下的正定矩阵的复合矩阵是否仍然是正定的研究需要利用一般的正定矩阵的标准形的复合矩阵进行讨论,给出了一般公式及具体算法,为讨论其复合矩阵的正定性提供了基础条件. 相似文献
103.
Laura Montanaro K. Belgacem P. Llewellyn F. Rouquerol F. Merlo Paola Palmero 《Journal of Thermal Analysis and Calorimetry》2007,88(3):789-793
Wet chemical synthesis of precursor oxide ceramics is a method to obtain small particulate powders. Such powders are far more
prone to ageing in air than more traditional precursors. Thermogravimetric analysis is used to highlight the species responsible
for the ageing of ceramic precursors. Indeed water and carbon dioxide are observed to evolve from aged powders. Ceramics obtained
from aged precursors can reach a very low final density with respect to the theoretical value. A large degree of the original
sintering properties can be recovered after washing the aged powders with ethanol in a basic medium. 相似文献
104.
本文研究了独立随机变量之和的绝对矩的几个性质, 其中包括$\ep|X+Y|-\ep|X-Y|$的表达式, 这里$X$和$Y$是相互独立的随机变量. 相似文献
105.
106.
本文解决了超立方体的Laplace矩阵的谱问题.n维超立方体Q。的Laplace矩阵L(Q)的谱specL(Qn)。[0 2 4…2n Cn^0 Cn^1 Cn^2 … Cn^n],.其中2t(t=0,1,2,…,n)为L(Qn)的n+1个不同的特征值,二项式系数Cn为特征值2t的重数. 相似文献
107.
108.
109.
110.
Arne Barinka Stephan Dahlke Wolfgang Dahmen 《Advances in Computational Mathematics》2006,24(1-4):5-34
Recently adaptive wavelet methods have been developed which can be shown to exhibit an asymptotically optimal accuracy/work
balance for a wide class of variational problems including classical elliptic boundary value problems, boundary integral equations
as well as certain classes of noncoercive problems such as saddle point problems. A core ingredient of these schemes is the
approximate application of the involved operators in standard wavelet representation. Optimal computational complexity could
be shown under the assumption that the entries in properly compressed standard representations are known or computable in
average at unit cost. In this paper we propose concrete computational strategies and show under which circumstances this assumption
is justified in the context of elliptic boundary value problems.
Dedicated to Charles A. Micchelli on the occasion of his 60th birthday
Mathematics subject classifications (2000) 41A25, 41A46, 65F99, 65N12, 65N55.
This work has been supported in part by the Deutsche Forschungsgemeinschaft SFB 401, the first and third author are supported
in part by the European Community's Human Potential Programme under contract HPRN-CT-202-00286 (BREAKING COMPLEXITY). The
second author acknowledges the financial support provided through the European Union's Human Potential Programme, under contract
HPRN-CT-2002-00285 (HASSIP) and through DFG grant DA 360/4–1. 相似文献