全文获取类型
收费全文 | 2334篇 |
免费 | 113篇 |
国内免费 | 242篇 |
专业分类
化学 | 511篇 |
晶体学 | 19篇 |
力学 | 132篇 |
综合类 | 28篇 |
数学 | 1199篇 |
物理学 | 800篇 |
出版年
2023年 | 33篇 |
2022年 | 38篇 |
2021年 | 44篇 |
2020年 | 40篇 |
2019年 | 73篇 |
2018年 | 60篇 |
2017年 | 79篇 |
2016年 | 72篇 |
2015年 | 64篇 |
2014年 | 128篇 |
2013年 | 187篇 |
2012年 | 90篇 |
2011年 | 128篇 |
2010年 | 146篇 |
2009年 | 158篇 |
2008年 | 158篇 |
2007年 | 131篇 |
2006年 | 117篇 |
2005年 | 122篇 |
2004年 | 104篇 |
2003年 | 61篇 |
2002年 | 81篇 |
2001年 | 53篇 |
2000年 | 48篇 |
1999年 | 44篇 |
1998年 | 44篇 |
1997年 | 40篇 |
1996年 | 30篇 |
1995年 | 26篇 |
1994年 | 24篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 6篇 |
1990年 | 16篇 |
1989年 | 17篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 17篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 7篇 |
排序方式: 共有2689条查询结果,搜索用时 328 毫秒
41.
In this work, the gold nanoparticle self-assembly behavior of mica-surface-confined polyelectrolyte/surfactant complex films was investigated. First, modified partially hydrated polyacrylamide (MHPAM)/hexadecyltrimethylammonium bromide (CTAB) complex films were deposited on the mica surface using Langmuir–Blodgett technique. Then, the preadsorbed MHPAM/CTAB complex film mica plate was dipped into the gold aqueous solution and the interesting fractal nanostructured gold network was formed. In addition, the effect of dipping time on gold nanoparticle self-assembly morphology was studied. The mechanism of formation process is briefly proposed. 相似文献
42.
Robert G. Behrens 《Journal of organometallic chemistry》1976,121(3):C63-C65
The results of low temperature heat capacity studies on Mn2(CO)10(s) and Re2(CO)10(s) are compared with literature reports. It is shown that the values of vaporization enthalpies and entropies correspond with those of the low temperature stable phase. 相似文献
43.
高抗冲聚苯乙烯的增韧机理 总被引:12,自引:0,他引:12
概述了以高抗冲聚苯乙烯(HIPS)为中心的有关橡胶增韧机理的理论,并且总结了界面,性能、粒子尺寸、粒 距及缠结密度等因素对橡胶/高分子共混体系性能的影响。 相似文献
44.
建立了处理双原子分子-表面相互作用的推广的LEPS势.借助推广的LEPS势,系统研究了一氧化碳分子在铂低指数表面吸附的动力学特性,重现了低指数表面的分子吸附热、吸附几何及本征振动等实验数据;鉴定了某些不合理的文献信息,预测了实验尚未探测到的重要信息:预测到Pt(100)表面四重洞位的C-O伸缩振动频率为1 962.60 cm-1;预测到Pt(110)表面吸附态的C-O及C-Pt键长分别为115.1、147 pm. 相似文献
45.
Ram Manohar & Rajen Kumar Sinha 《计算数学(英文版)》2022,40(2):147-176
This article studies a posteriori error analysis of fully discrete finite element approximations for semilinear parabolic optimal control problems. Based on elliptic reconstruction approach introduced earlier by Makridakis and Nochetto [25], a residual based a posteriori error estimators for the state, co-state and control variables are derived. The space discretization of the state and co-state variables is done by using the piecewise linear and continuous finite elements, whereas the piecewise constant functions are employed for the control variable. The temporal discretization is based on the backward Euler method. We derive a posteriori error estimates for the state, co-state and control variables in the $L^\infty(0,T;L^2(\Omega))$-norm. Finally, a numerical experiment is performed to illustrate the performance of the derived estimators. 相似文献
46.
Hejun WANG 《数学年刊B辑(英文版)》2024,45(2):179-192
This paper concerns the even Lp Gaussian Minkowski problem in n-dimensional
Euclidean space R
n
. The existence of the solution to the even Lp Guassian Minkowski
problem for p > n is obtained. 相似文献
47.
In this paper we present and study a new algorithm for the Maximum Satisfiability (Max Sat) problem. The algorithm is based on the Method of Conditional Expectations (MOCE, also known as Johnson’s Algorithm) and applies a greedy variable ordering to MOCE. Thus, we name it Greedy Order MOCE (GO-MOCE). We also suggest a combination of GO-MOCE with CCLS, a state-of-the-art solver. We refer to this combined solver as GO-MOCE-CCLS.We conduct a comprehensive comparative evaluation of GO-MOCE versus MOCE on random instances and on public competition benchmark instances. We show that GO-MOCE reduces the number of unsatisfied clauses by tens of percents, while keeping the runtime almost the same. The worst case time complexity of GO-MOCE is linear. We also show that GO-MOCE-CCLS improves on CCLS consistently by up to about 80%.We study the asymptotic performance of GO-MOCE. To this end, we introduce three measures for evaluating the asymptotic performance of algorithms for Max Sat. We point out to further possible improvements of GO-MOCE, based on an empirical study of the main quantities managed by GO-MOCE during its execution. 相似文献
48.
Best possibility of the Furuta inequality 总被引:5,自引:0,他引:5
Let , and . Furuta (1987) proved that if bounded linear operators on a Hilbert space satisfy , then . In this paper, we prove that the range and is best possible with respect to the Furuta inequality, that is, if or , then there exist which satisfy but .
49.
The vertical ionization potentials of difluoramine are calculated by perturbation corrections to Koopmans' theorem. The calculation shows that difluoraimine has three overlapping bands between 15 and 16 eV. The calculated results compare well with the experimental values. The photoelectron spectrum of difluoramine is compared with that of OF2 and CH2F2. 相似文献
50.