全文获取类型
收费全文 | 2273篇 |
免费 | 449篇 |
国内免费 | 515篇 |
专业分类
化学 | 1433篇 |
晶体学 | 58篇 |
力学 | 93篇 |
综合类 | 25篇 |
数学 | 765篇 |
物理学 | 863篇 |
出版年
2024年 | 19篇 |
2023年 | 117篇 |
2022年 | 167篇 |
2021年 | 199篇 |
2020年 | 204篇 |
2019年 | 141篇 |
2018年 | 142篇 |
2017年 | 161篇 |
2016年 | 165篇 |
2015年 | 142篇 |
2014年 | 183篇 |
2013年 | 258篇 |
2012年 | 216篇 |
2011年 | 210篇 |
2010年 | 154篇 |
2009年 | 125篇 |
2008年 | 92篇 |
2007年 | 99篇 |
2006年 | 102篇 |
2005年 | 47篇 |
2004年 | 29篇 |
2003年 | 19篇 |
2002年 | 44篇 |
2001年 | 51篇 |
2000年 | 35篇 |
1999年 | 35篇 |
1998年 | 16篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 13篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1959年 | 2篇 |
1957年 | 1篇 |
1936年 | 3篇 |
排序方式: 共有3237条查询结果,搜索用时 187 毫秒
31.
Qing-yao Wang Jia-qi Fang Lu-lu Deng Xiao-jiang Hao Shu-zhen Mu 《Chemistry Central journal》2017,11(1):138
The regioselective demethoxylation and dehalogenation of dihalogenated dibenzocyclooctadiene lignans derivatives were realized in a one-step reaction with excellent yields in the sodium and t-butanol reaction system. 相似文献
32.
Yun-an Yan 《化学物理学报(中文版)》2017,30(3):277-286
A wide range of quantum systems are time-invariant and the corresponding dynamics is dictated by linear differential equations with constant coefficients.Although simple in mathematical concept,the integration of these equations is usually complicated in practice for complex systems,where both the computational time and the memory storage become limiting factors.For this reason,low-storage Runge-Kutta methods become increasingly popular for the time integration.This work suggests a series of s-stage sth-order explicit RungeKutta methods specific for autonomous linear equations,which only requires two times of the memory storage for the state vector.We also introduce a 13-stage eighth-order scheme for autonomous linear equations,which has optimized stability region and is reduced to a fifth-order method for general equations.These methods exhibit significant performance improvements over the previous general-purpose low-stage schemes.As an example,we apply the integrator to simulate the non-Markovian exciton dynamics in a 15-site linear chain consisting of perylene-bisimide derivatives. 相似文献
33.
研究了经典N=2李共形超代数的导子和第二上同调群的结构,并应用第二上同调群的结果确定了该李共形超代数的泛中心扩张. 相似文献
34.
35.
本文研究了复线性微分方程解的增长性问题.利用两类具有某种渐进增长性质的函数作为线性微分方程的系数,讨论了两类二阶线性微分方程解的增长性,获得了方程解为无穷级.这些结果推广了先前的一些结果. 相似文献
36.
37.
In this paper, we analyze finite time stability for a class of differential equations with finite delay. Some sufficient conditions for the finite time stability results are derived based on delayed matrix exponential approach and Jensen’s and Coppel’s inequalities. Finally, we demonstrate the validity of designed method and make some discussions by using a numerical example. 相似文献
38.
39.
《中国化学快报》2023,34(5):107821
We report the Lewis acid catalysis of aryldiazonium salts, and their Lewis acidity applications in photogeneration of aryl radicals under additive-, photocatalyst- and transition metal-free conditions. In this visible light-mediated transformation, the Lewis acidic character of aryldiazonium salts enables access to the photoactive charge transfer complex with dichalcogenides. The usefulness and versatility of this new protocol are demonstrated through the chalcogenation of a variety of aryldiazonium salts. 相似文献
40.
《中国化学快报》2023,34(7):107811
Herein, a bidirectional polarization strategy is proposed for hosting efficient and durable lithium-sulfur battery (Li-S) electrochemistry. By co-doping electronegative N and electropositive B in graphene matrix (BNrGO), the bidirectional electron redistribution enables a higher polysulfide affinity over its mono-doped counterparts, contributing to strong sulfur immobilization and fast conversion kinetics. As a result, BNrGO as the cathode host matrix realizes excellent cycling stability over 1000 cycles with a minimum capacity fading of 0.027% per cycle, and superb rate capability up to 10 C. Meanwhile, decent areal capacity (6.46 mAh/cm2) and cyclability (300 cycles) are also achievable under high sulfur loading and limited electrolyte. This work provides instructive insights into the interaction between doping engineering and sulfur electrochemistry for pursuing superior Li-S batteries. 相似文献