全文获取类型
收费全文 | 6741篇 |
免费 | 430篇 |
国内免费 | 505篇 |
专业分类
化学 | 1575篇 |
晶体学 | 13篇 |
力学 | 300篇 |
综合类 | 70篇 |
数学 | 2316篇 |
物理学 | 817篇 |
综合类 | 2585篇 |
出版年
2024年 | 6篇 |
2023年 | 44篇 |
2022年 | 87篇 |
2021年 | 115篇 |
2020年 | 119篇 |
2019年 | 133篇 |
2018年 | 131篇 |
2017年 | 140篇 |
2016年 | 179篇 |
2015年 | 131篇 |
2014年 | 278篇 |
2013年 | 370篇 |
2012年 | 377篇 |
2011年 | 372篇 |
2010年 | 337篇 |
2009年 | 378篇 |
2008年 | 335篇 |
2007年 | 474篇 |
2006年 | 411篇 |
2005年 | 391篇 |
2004年 | 304篇 |
2003年 | 323篇 |
2002年 | 237篇 |
2001年 | 232篇 |
2000年 | 221篇 |
1999年 | 175篇 |
1998年 | 157篇 |
1997年 | 128篇 |
1996年 | 130篇 |
1995年 | 95篇 |
1994年 | 128篇 |
1993年 | 93篇 |
1992年 | 100篇 |
1991年 | 86篇 |
1990年 | 88篇 |
1989年 | 66篇 |
1988年 | 68篇 |
1987年 | 42篇 |
1986年 | 40篇 |
1985年 | 35篇 |
1984年 | 24篇 |
1983年 | 10篇 |
1982年 | 25篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1969年 | 3篇 |
排序方式: 共有7676条查询结果,搜索用时 15 毫秒
1.
对300℃时Mg-Zn-Ce系富镁侧化合物的成分特征、结构和相平衡关系进行了研究.结果表明,Mg-Zn-Ce富镁角存在一个Mg12Ce的二元置换固溶体(Mg,Zn)12Ce,还存在一个三元线性化合物(Mg,Zn)11Ce(τ相).(Mg,Zn)12Ce中Zn的范围为0~7.3%(原子分数),其晶体结构为体心四方晶格.三元线性化合物τ相含Zn为8.5%~43.5%(原子分数),其晶体结构为C底心正交晶格.(Mg,Zn)12Ce和τ相均与α(Mg)存在稳定的两相平衡,且在Mg-Zn-Ce系富镁角还存在三相平衡Mg+(Mg,Zn)12Ce+τ. 相似文献
2.
从编辑学角度分析了平衡范畴的含义、类型和特性.认为质平衡是具有科技编辑特色的平衡范畴类型.平衡范畴具有方法论意义的特性在于:平衡态较易把握;非平衡态引导深化;平衡与非平衡始终是对立统一的.科技编辑应树立平衡意识,充分发挥平衡范畴及其方法的理论意义及实践价值. 相似文献
3.
Dean A. Carlson 《Journal of Mathematical Analysis and Applications》2002,276(2):561-588
The method of equivalent variational methods, originally due to Carathéodory for free problems in the calculus of variations is extended to investigate feedback Nash equilibria for a class of n-person differential games. Both the finite-horizon and infinite-horizon cases are considered. Examples are given to illustrate the presented results. 相似文献
4.
MC模式下顾客需求与厂商供应的纳什均衡 总被引:3,自引:0,他引:3
在大规模定制(MC,Mass Customization)模式下,基于市场需求的复杂化,厂商对个性化的顾客需求很难做出及时准确的反应,而且由于其自身生产能力的限制,不可能对所有的个性化用户进行一一地满足,只可能对已经存在的个性化需求,根据自身的生产能力和规模,以利润最大化及顾客对产品的满意度为目标,对个性化需求进行较准确地预测,从而正确指导生产。本通过博弈论的方法,提出了一个基于顾客对产品的满意度及企业的利润的一个非合作博弈模型,并给出求解纳什均衡的方法。 相似文献
5.
6.
Yuh-Shan Ho 《Adsorption》2004,10(2):151-158
The kinetics of four sorption systems, Cu/tree fern, Pb/tree fern, AB9/activated clay and BR18/activated clay have been studied based on the assumption of a pseudo-second order rate law. Pseudo-isotherms using the pseudo-second order kinetic expression constant have been developed to describe the four liquid-solid sorption systems. The experimental results have been analyzed using a pseudo-Langmuir and a pseudo-Redlich-Peterson isotherm. Both isotherms were found to represent the measured sorption data well. According to the evaluation using the pseudo-Langmuir equation, the monolayer sorption capacities were obtained to be 13.9, 46.6, 124 and 105 mg g–1 for copper, lead, AB9 and BR18 respectively. 相似文献
7.
Hidetaka Tobita 《Journal of Polymer Science.Polymer Physics》2004,42(14):2801-2812
The matrix formula developed in the context of heterochain theory, M?w = M?wp + WF ( I ? M )?1 S , was applied to describe the molecular weight development during free‐radical multicomponent polymerization. All of the required probabilistic parameters are expressed in terms of the kinetic‐rate constants and the various concentrations associated with them. In free‐radical polymerization, the number of heterochain types, N, needs to be extrapolated to infinity, and such extrapolation is conducted with only three different N values. This matrix formula can be used as a benchmark test if other approximate approaches can give reasonable estimates of the weight‐average molecular weights. The moment equations with the average pseudo‐kinetic‐rate constants for branching and crosslinking reactions may provide poor estimates when the copolymer composition drift during polymerization is very significant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2801–2812, 2004 相似文献
8.
For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions. 相似文献
9.
A carousel is a dynamical system that describes the movement of an equilateral linkage in which the midpoint of each rod travels parallel to it. They are closely related to the floating body problem. We prove, using the work of Auerbach, that any figure that floats in equilibrium in every position is drawn by a carousel. Of special interest are such figures with rational perimetral density of the floating chords, which are then drawn by carousels. In particular, we prove that for some perimetral densities the only such figure is the circle, as the problem suggests. 相似文献
10.
Yang Woo Shin 《Operations Research Letters》2004,32(4):364-373
We consider a single server queue with disasters where the arrivals of customers and disasters are correlated. When a disaster occurs, it removes all the customers in the system and there requires repair time for the system to be operated normally. The stationary queue length distribution at the embedded points and at an arbitrary time are presented. 相似文献