全文获取类型
收费全文 | 3485篇 |
免费 | 492篇 |
国内免费 | 276篇 |
专业分类
化学 | 209篇 |
晶体学 | 4篇 |
力学 | 290篇 |
综合类 | 78篇 |
数学 | 3354篇 |
物理学 | 318篇 |
出版年
2024年 | 10篇 |
2023年 | 37篇 |
2022年 | 30篇 |
2021年 | 63篇 |
2020年 | 101篇 |
2019年 | 96篇 |
2018年 | 121篇 |
2017年 | 158篇 |
2016年 | 150篇 |
2015年 | 97篇 |
2014年 | 129篇 |
2013年 | 291篇 |
2012年 | 163篇 |
2011年 | 184篇 |
2010年 | 145篇 |
2009年 | 160篇 |
2008年 | 180篇 |
2007年 | 227篇 |
2006年 | 217篇 |
2005年 | 194篇 |
2004年 | 158篇 |
2003年 | 171篇 |
2002年 | 169篇 |
2001年 | 157篇 |
2000年 | 126篇 |
1999年 | 117篇 |
1998年 | 93篇 |
1997年 | 91篇 |
1996年 | 62篇 |
1995年 | 66篇 |
1994年 | 48篇 |
1993年 | 39篇 |
1992年 | 37篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1957年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有4253条查询结果,搜索用时 562 毫秒
121.
The aim of this paper is to study the existence and the asymptotic behavior of solutions for some reaction–diffusion equations arising in epidemic biology phenomena. We will show that for a rather broad class of nonlinearities, the solutions are global and uniformly bounded, and under suitable assumptions on the parameters of the system, these solutions converge as time goes to infinity to a disease‐free equilibrium point. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
122.
123.
124.
《高分子科学杂志,C辑:聚合物评论》2013,53(2):99-124
Thermally stimulated recovery (TSR) is a non‐conventional mechanical spectroscopy technique that allows to analyse in detail the relaxation processes of polymeric systems in the low frequency region. This work reviews the main aspects and potentialities of this technique. The different kinds of TSR experiments that can be performed, global and thermal sampling (TS) experiments, are described and illustrated with several examples. Also, the different methods for the determination of the thermokinetic parameters (activation energy and pre‐exponential factor) of the thermal sampling (TS) procedure are explained and compared. In this context, the compensation phenomenon, which always appears in TSR results when the studies are performed in the glass transition region of a given system, is discussed. Examples of the application of this technique to different polymeric systems during the last 20 years are provided. An emphasis will be made on the analysis of the effect of crystallinity degree and crosslink density on the TSR response. A comparison between the results (characteristic times and activation energies) obtained by different techniques, namely TSR, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC), is made. 相似文献
125.
本文简要介绍了势能面搜索的两个主要问题,即过渡态搜索和全局势能面搜索,并针对这两个问题介绍了本研究组最近发展的3种方法,即限制最小化双子算法、偏置势函数辅助限制性最小化双子算法以及势能面随机行走方法.这3种方法均只需计算一阶梯度,能够用于快速自动化的搜索过渡态以及势能面.通过几个典型例子分别说明了3种方法的特点及优势. 相似文献
126.
Vando Narciso 《Mathematical Methods in the Applied Sciences》2015,38(4):775-784
This paper is concerned with the existence of a global attractor for the nonlinear viscoelastic beam equation with past history memory where g(ut) is a damping like | ut | rut and f(u) is a source term like | u | αu ? | u | βu, by considering 0 ≤ β < α and r > 0. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
127.
In this paper, applying both Lyapunov function techniques and monotone iterative techniques, we establish new sufficient conditions under which the infected equilibrium of an HIV pathogenesis model with cure rate is globally asymptotically stable. By giving an explicit expression for eventual lower bound of the concentration of susceptible CD4+ T cells, we establish an affirmative partial answer to the numerical simulations investigated in the recent paper [Liu, Wang, Hu and Ma, Global stability of an HIV pathogenesis model with cure rate, Nonlinear Analysis RWA (2011) 12 : 2947–2961]. Our monotone iterative techniques are applicable for the small and large growth rate in logistic functions for the proliferation rate of healthy and infected CD4+ T cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
128.
129.
130.
The READY program: Building a global potential energy surface and reactive dynamic simulations for the hydrogen combustion
下载免费PDF全文
![点击此处可从《Journal of computational chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
READY (REActive DYnamics) is a program for studying reactive dynamic systems using a global potential energy surface (PES) built from previously existing PESs corresponding to each of the most important elementary reactions present in the system. We present an application to the combustion dynamics of a mixture of hydrogen and oxygen using accurate PESs for all the systems involving up to four oxygen and hydrogen atoms. Results at the temperature of 4000 K and pressure of 2 atm are presented and compared with model based on rate constants. Drawbacks and advantages of this approach are discussed and future directions of research are pointed out. © 2014 Wiley Periodicals, Inc. 相似文献