全文获取类型
收费全文 | 141898篇 |
免费 | 9063篇 |
国内免费 | 7726篇 |
专业分类
化学 | 50066篇 |
晶体学 | 1348篇 |
力学 | 8892篇 |
综合类 | 395篇 |
数学 | 35663篇 |
物理学 | 29447篇 |
综合类 | 32876篇 |
出版年
2024年 | 241篇 |
2023年 | 971篇 |
2022年 | 1792篇 |
2021年 | 1956篇 |
2020年 | 1939篇 |
2019年 | 1824篇 |
2018年 | 12040篇 |
2017年 | 11994篇 |
2016年 | 8403篇 |
2015年 | 3677篇 |
2014年 | 3944篇 |
2013年 | 4690篇 |
2012年 | 8947篇 |
2011年 | 16101篇 |
2010年 | 10355篇 |
2009年 | 10748篇 |
2008年 | 11561篇 |
2007年 | 13444篇 |
2006年 | 4042篇 |
2005年 | 4388篇 |
2004年 | 3994篇 |
2003年 | 4054篇 |
2002年 | 3212篇 |
2001年 | 2239篇 |
2000年 | 1870篇 |
1999年 | 1546篇 |
1998年 | 1158篇 |
1997年 | 988篇 |
1996年 | 974篇 |
1995年 | 761篇 |
1994年 | 702篇 |
1993年 | 552篇 |
1992年 | 451篇 |
1991年 | 396篇 |
1990年 | 343篇 |
1989年 | 289篇 |
1988年 | 236篇 |
1987年 | 187篇 |
1986年 | 159篇 |
1985年 | 105篇 |
1984年 | 69篇 |
1983年 | 64篇 |
1982年 | 54篇 |
1981年 | 53篇 |
1980年 | 57篇 |
1979年 | 61篇 |
1978年 | 41篇 |
1914年 | 46篇 |
1912年 | 41篇 |
1909年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
Julio Castellanos 《Mathematische Zeitschrift》2002,239(4):777-802
We consider complete ideals supported on finite sequences of infinitely near points, in regular local rings with dimensions
greater than two. We study properties of factorizations in Lipman special *-simple complete ideals. We relate it to a type
of proximity, linear proximity, of the points, and give conditions in order to have unique factorization. Several examples
are presented.
Received: 2 February 2000 / in final form: 14 March 2001 / Published online: 18 January 2002 相似文献
112.
113.
114.
可变抽样区间的非参数控制图 总被引:1,自引:1,他引:0
最近几年一些学者研究了可变抽样区间的质量控制图。Amin等提出了可变抽样区间(VSI)的非参数控制图———符号 (Sign)统计量图〔1〕。本文在此基础上研究位置VSI符号控制图的制定方法 ,并设计离散VSI符号控制图。符号控制图的优点是对非正态总体亦可应用 ,并且不需要过程方差的信息。本文将所设计的VSI符号控制图同固定抽样区间 (FSI)的常规图作比较 ,并举实例说明符号控制图的应用 相似文献
115.
Alexander Krasnosel'skii Dmitrii Rachinskii 《NoDEA : Nonlinear Differential Equations and Applications》2002,9(1):93-115
We consider autonomous systems with a nonlinear part depending on a parameter and study Hopf bifurcations at infinity. The
nonlinear part consists of the nonlinear functional term and the Prandtl--Ishlinskii hysteresis term. The linear part of the
system has a special form such that the close-loop system can be considered as a hysteresis perturbation of a quasilinear
Hamiltonian system. The Hamiltonian system has a continuum of arbitrarily large cycles for each value of the parameter. We
present sufficient conditions for the existence of bifurcation points for the non-Hamiltonian system with hysteresis. These
bifurcation points are determined by simple characteristics of the hysteresis nonlinearity. 相似文献
116.
Claudia-Elisabeth Wulz 《Czechoslovak Journal of Physics》2002,52(3):C155-C170
The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described. 相似文献
117.
The existence and uniqueness of classical global solutions to a type of Boussinesq equations with initial and boundary values are studied in this paper. The existence of such solutions is proved by means of compactness theorem and Schauders fixed point theorem, and its uniqueness by the so called energy method.Projects Supported by the Science Fund of the Chinese Academy of Sciences. 相似文献
118.
激光诱导荧光探测水体中溶解有机物浓度 总被引:2,自引:2,他引:0
用Nd∶YAG激光器的三倍频355 nm光作为激发光源,根据激光诱导荧光(LIF)方法激发并探测污染水体的荧光光谱.通过对荧光光谱的分析处理研究归一化荧光强度,即450 nm处水中溶解有机物(DOM)峰与405 nm处水的拉曼峰的比值,反演溶解有机物浓度.用商品腐殖酸和去离子水配置成已知浓度的溶液代替标准DOM溶液进行标定,得到回归方程.结果证明,DOM的归一化荧光强度与水体中DOM浓度有较好的线性关系,因此LIF方法是对大面积水域水质进行动态遥测的较理想方法. 相似文献
119.
This paper proposes two constructive heuristics for the well-known single-level uncapacitated dynamic lot-sizing problem. The proposed heuristics, called net least period cost (nLPC) and nLPC(i), are developed by modifying the average period cost concept from Silver and Meal's heuristic, commonly known as least period cost (LPC). An improved tie-breaking stopping rule and a locally optimal decision rule are proposed in the second heuristic to enhance performance. We test the effectiveness of the proposed heuristics by using 20 benchmarking test problems frequently used in the literature. Furthermore, we perform a large-scale simulation study involving three factors, 50 experimental conditions, and 100?000 randomly generated problems to evaluate the proposed heuristics against LPC and six other well-known constructive heuristics in the literature. The simulation results show that both nLPC and nLPC(i) produce average holding and setup costs lower than or equal to those of LPC in every one of the 50 experimental conditions. The proposed heuristics also outperform each of the six other heuristics evaluated in all experimental conditions, without an increase in computational requirements. Lastly, considering that both nLPC and nLPC(i) are fairly simple for practitioners to understand and that lot-sizing heuristics have been commonly used in practice, there should be a very good chance for practical applications of the proposed heuristics. 相似文献
120.
应用程序用户界面设计 总被引:3,自引:0,他引:3
随着计算机软、硬件技术的发展,应用程序用户界面的重要性与日俱增,而在设计程序时如何合理的编排、处理界面元素,设计出美观实用的用户界面,本文将作出论述。 相似文献