全文获取类型
收费全文 | 9313篇 |
免费 | 271篇 |
国内免费 | 48篇 |
专业分类
化学 | 6837篇 |
晶体学 | 46篇 |
力学 | 116篇 |
数学 | 1442篇 |
物理学 | 1191篇 |
出版年
2020年 | 100篇 |
2019年 | 95篇 |
2016年 | 200篇 |
2015年 | 187篇 |
2014年 | 153篇 |
2013年 | 326篇 |
2012年 | 341篇 |
2011年 | 457篇 |
2010年 | 237篇 |
2009年 | 246篇 |
2008年 | 381篇 |
2007年 | 406篇 |
2006年 | 391篇 |
2005年 | 418篇 |
2004年 | 355篇 |
2003年 | 302篇 |
2002年 | 279篇 |
2001年 | 138篇 |
2000年 | 121篇 |
1999年 | 125篇 |
1998年 | 130篇 |
1997年 | 151篇 |
1996年 | 141篇 |
1995年 | 134篇 |
1994年 | 124篇 |
1993年 | 140篇 |
1992年 | 127篇 |
1991年 | 123篇 |
1990年 | 94篇 |
1989年 | 120篇 |
1988年 | 128篇 |
1987年 | 117篇 |
1986年 | 121篇 |
1985年 | 156篇 |
1984年 | 125篇 |
1983年 | 125篇 |
1982年 | 127篇 |
1981年 | 119篇 |
1980年 | 118篇 |
1979年 | 104篇 |
1978年 | 105篇 |
1977年 | 97篇 |
1976年 | 92篇 |
1974年 | 101篇 |
1973年 | 97篇 |
1971年 | 77篇 |
1961年 | 141篇 |
1960年 | 195篇 |
1959年 | 103篇 |
1958年 | 115篇 |
排序方式: 共有9632条查询结果,搜索用时 312 毫秒
51.
The new linear triamine 2,6-bis(pyrrolidin-2-yl)pyridine ( II ) has been synthesized, and the (R, S)-, (R, R)-, and (S, S)-isomers have been separated. Compared to other triamines showing a similar structure, these new ligands form very stable Cu2+ complexes. No significant difference is observed between the meso and the racemic forms for their binary or ternary mixed-ligand complexes with the amino acids alanine and proline. 相似文献
52.
First examples of amphiphilic alkyl pentakis(phenylethynyl)benzene ethers containing functional groups at the terminal position of their alkoxy chains were synthesized by etherification of pentabromophenol with 11-bromoundecan-1-ol and 11-bromoundecanoic acid ethyl ester, respectively, and subsequent palladium catalyzed, fivefold coupling reactions with the substituted phenylacetylene. Two undecanoic acid derivatives with different pentakis(phenylethynyl)phenoxy substituents in the ω-position were prepared by ester cleavage from the corresponding ethyl esters. The thermal behaviours of five penta-alkynes in their pure states, as well as of their charge transfer complexes formed from mixtures with 2,4,7-tri-nitrofluorenone, were examined. 相似文献
53.
54.
55.
We analyze the quantum measurement properties of dual non-degenerate parametric amplifers in the twin-beam configuration,
in the cascaded back-action-evasion configuration, and in Kerr-type photon-number quantum non-demolition measurements. It
is found that Einstein-Podolsky-Rosen correlations can be obtained between the quadrature components of an idler mode and
the sum of the readout of two signal modes. Furthermore, we discuss dual-mode quantum non-demolition measurements on the combination
of two light modes, and the generation of number-state entanglement.
Received: 12 April 1996/Revised version: 2 July 1996 相似文献
56.
57.
Anders Karlhede 《General Relativity and Gravitation》2006,38(6):1109-1114
The equivalence problem is the problem of deciding whether two metric tensors are related by a coordinate transformation or not. I give a brief historical review of work done on this problem in Stockholm around 1980. 相似文献
58.
59.
60.
Klaus Ziegler 《Journal of multivariate analysis》1997,62(2):233-272
Functional central limit theorems for triangular arrays of rowwise independent stochastic processes are established by a method replacing tail probabilities by expectations throughout. The main tool is a maximal inequality based on a preliminary version proved by P. Gaenssler and Th. Schlumprecht. Its essential refinement used here is achieved by an additional inequality due to M. Ledoux and M. Talagrand. The entropy condition emerging in our theorems was introduced by K. S. Alexander, whose functional central limit theorem for so-calledmeasure-like processeswill be also regained. Applications concern, in particular, so-calledrandom measure processeswhich include function-indexed empirical processes and partial-sum processes (with random or fixed locations). In this context, we obtain generalizations of results due to K. S. Alexander, M. A. Arcones, P. Gaenssler, and K. Ziegler. Further examples include nonparametric regression and intensity estimation for spatial Poisson processes. 相似文献