全文获取类型
收费全文 | 3122篇 |
免费 | 97篇 |
国内免费 | 18篇 |
专业分类
化学 | 2044篇 |
晶体学 | 15篇 |
力学 | 61篇 |
数学 | 531篇 |
物理学 | 586篇 |
出版年
2023年 | 23篇 |
2022年 | 18篇 |
2021年 | 76篇 |
2020年 | 77篇 |
2019年 | 65篇 |
2018年 | 52篇 |
2017年 | 62篇 |
2016年 | 109篇 |
2015年 | 90篇 |
2014年 | 100篇 |
2013年 | 223篇 |
2012年 | 231篇 |
2011年 | 243篇 |
2010年 | 147篇 |
2009年 | 119篇 |
2008年 | 177篇 |
2007年 | 183篇 |
2006年 | 168篇 |
2005年 | 130篇 |
2004年 | 114篇 |
2003年 | 93篇 |
2002年 | 87篇 |
2001年 | 39篇 |
2000年 | 38篇 |
1999年 | 43篇 |
1998年 | 28篇 |
1997年 | 36篇 |
1996年 | 28篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 22篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 28篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 18篇 |
1981年 | 27篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1974年 | 11篇 |
1973年 | 6篇 |
1972年 | 7篇 |
排序方式: 共有3237条查询结果,搜索用时 15 毫秒
1.
Synthesis of diisocyanides with phenolic groups and their polymerization to helically chiral poly(quinoxaline‐2,3‐diyl)s 下载免费PDF全文
Johannes Scholz Michael Reggelin 《Journal of polymer science. Part A, Polymer chemistry》2015,53(11):1320-1329
The development of synthetic routes which lead to five new diisocyanide monomers with one or two phenolic groups is described. Their polymerization behavior is studied with Pd‐ and Ni‐based initiators, as well as under microwave irradiation. The polymerizability is mainly dominated by steric effects as is concluded from experiments using different protecting groups. Chiroptical properties of these new polymers are studied by CD‐spectroscopy. After deprotection, helically chiral poly(quinoxalin‐2,3‐diyl)s are obtained which display a Brønsted function attached to a stereolabile biaryl axis whose configuration should be influenced by the chiral polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1320–1329 相似文献
2.
3.
Ricardo Celorrio Vı́ctor Domínguez Francisco-Javier Sayas 《Comptes Rendus Mathematique》2002,334(10):923-926
In this work we study the solution of Laplace's equation in a domain with holes by an iteration consisting of splitting the problem in an exterior one, around the holes, plus an interior problem in the unholed domain. We show the existence of a decomposition of the solution when the exterior problem is represented by means of a single-layer protential. Also, for the three-dimensional case and with some adjustments for the two-dimensional case, we prove convergence of the method by writing the iteration as a Jacobi iteration for an operator equation and studying the spectrum of the iteration operator. To cite this article: R. Celorrio et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 923–926. 相似文献
4.
Tereza C. R. dos Santos Ricardo Q. Aucélio Reinaldo C. Campos 《Mikrochimica acta》2003,142(1-2):63-66
A simple and direct spectrofluorimetric method has been developed for the determination of aluminum using alizarin red PS
(1,2,4-trihydroxy 9,10-anthraquinone-3-sulfonic acid). The method is based on the strong fluorescence (480/564 nm) of Al3+ and alizarin red. Experimental parameters such as pH, concentration of the ligand, ionic strength of the solution, reaction
time and temperature were optimized in order to maximize the analytical signal. Interferences of several ions (anions and
cations) were studied and evaluated. The linear range of the method extends from 3 to 100 μg L−1. Limit of detection (3sb) was 0.9 μg L−1. The method was tested with a silicate certified reference material. Interferences were eliminated by a liquid extraction
with cupferron.
Author for correspondence. E-mail: aucelior@rdc.puc-rio.br
Received September 10, 2002; accepted January 15, 2003
Published online May 5, 2003 相似文献
5.
6.
Ricardo Mañé 《Bulletin of the Brazilian Mathematical Society》1997,28(2):141-153
The objective of this note is to present some results, to be proved in a forthcoming paper, about certain special solutions of the Euler-Lagrange equations on closed manifolds. Our main results extend to time dependent periodic Lagrangians with minor modifications.We have chosen the autonomous case because this formally simpler framework allows to reach more easily the core of our concepts and results. Moreover the autonomous case exhibits certain special features involving the energy as a first integral that deserve special attention. They are closely related to the link found by Carneiro [C] between the energy and Mather's action function [Ma].Reprinted by permission of Addison Wesley Longman Ltd. 相似文献
7.
Ricardo García-Pelayo Iván Salazar William C. Schieve 《Journal of statistical physics》1993,72(1-2):167-187
An analytically solvable model for sand avalanches of noninteracting grains of sand, based on the Chapman-Kolmogorov equations, is presented. For a single avalanche, distributions of lifetimes, sizes of overflows and avalanches, and correlation functions are calculated. Some of these are exponentials, some are power laws. Spatially homogeneous distributions of avalanches are also studied. Computer simulations of avalanches of interacting grains of sand are compared to the solutions to the Chapman-Kolmogorov equations. We find that within the range of parameters explored in the simulation, the approximation of noninteracting grains of sand is a good one. 相似文献
8.
9.
10.