首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   48186篇
  免费   3139篇
  国内免费   3422篇
化学   19990篇
晶体学   393篇
力学   3799篇
综合类   498篇
数学   10444篇
物理学   19623篇
  2024年   72篇
  2023年   430篇
  2022年   1057篇
  2021年   1048篇
  2020年   1086篇
  2019年   1112篇
  2018年   963篇
  2017年   1111篇
  2016年   1240篇
  2015年   976篇
  2014年   1565篇
  2013年   2953篇
  2012年   1860篇
  2011年   2062篇
  2010年   1669篇
  2009年   2730篇
  2008年   2975篇
  2007年   3365篇
  2006年   2835篇
  2005年   2219篇
  2004年   1856篇
  2003年   2149篇
  2002年   2558篇
  2001年   1923篇
  2000年   1828篇
  1999年   1543篇
  1998年   1507篇
  1997年   864篇
  1996年   830篇
  1995年   715篇
  1994年   772篇
  1993年   565篇
  1992年   641篇
  1991年   425篇
  1990年   407篇
  1989年   314篇
  1988年   277篇
  1987年   274篇
  1986年   244篇
  1985年   224篇
  1984年   227篇
  1983年   139篇
  1982年   187篇
  1981年   181篇
  1980年   119篇
  1979年   149篇
  1978年   126篇
  1977年   118篇
  1976年   74篇
  1973年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
对于工学硕士的《数理统计》教学的研究   总被引:3,自引:0,他引:3  
滕素珍 《大学数学》2003,19(4):22-25
工学硕士的《数理统计》教学 ,要根据工学硕士的培养目标和数理统计课程的特点编写教材、确定讲授内容和授课方式 .力求使学员掌握处理随机数据的思考方法 ,培养解决问题、分析问题和善于应用知识的能力 .改革《数理统计》教学 ,实现和普及多媒体教学是时代发展的趋势 .  相似文献   
142.
143.
New Exact Solutions to the Combined KdV and mKdV Equation   总被引:2,自引:0,他引:2  
The modified mapping method is developed to obtain new exact solutions to the combined KdV and mKdV equation. The method is applicable to a large variety of nonlinear evolution equations, as long as odd- and even-order derivative terms do not coexist in the equation under consideration.  相似文献   
144.
145.
Bush连续不可微函数的分形性质   总被引:1,自引:0,他引:1  
本文对用递推关系确定的Bush连续不可微函数,找出了迭代函数系(IFS),从而得到它的级数表达式和所具有的自仿射分形的有关性质.最后还计算出函数图象的Hausdorff 维数的准确值.  相似文献   
146.
We briefly review the five possible real polynomial solutions of hypergeometric differential equations. Three of them are the well known classical orthogonal polynomials, but the other two are different with respect to their orthogonality properties. We then focus on the family of polynomials which exhibits a finite orthogonality. This family, to be referred to as the Romanovski polynomials, is required in exact solutions of several physics problems ranging from quantum mechanics and quark physics to random matrix theory. It appears timely to draw attention to it by the present study. Our survey also includes several new observations on the orthogonality properties of the Romanovski polynomials and new developments from their Rodrigues formula.  相似文献   
147.
The paper aims to obtain existence and uniqueness of the solution as well as asymptotic estimate of the solution for singularly perturbed nonlinear third- order Robin boundary value problem with a turning point.In order to achieve this aim,existence and uniqueness of the solution for third-order nonlinear Robin boundary value problem is derived first based on the upper and lower solutions method under relatively weaker conditions.In this manner,the goal of this paper is gained by applying the existence and uniqueness results mentioned above.  相似文献   
148.
The results of studies on electrosynthesis involving carb- and heteroanions generated by cathodic deprotonation of acids (CDA), carried out in the laboratory headed by the author, are surveyed. These studies resulted in the elaboration of efficient electrochemical versions of the known Michaelis-Becker, Wittig-Horner, and Perkin reactions; electrochemical analogs of homolytic aromatic substitution, alkylation, heterocyclization,etc. were developed. Based on CDA, convenient and promising methods for preparing variousN-, O-, P-, S-, andC-alkylated and arylated substances have been developed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1411–1422, August, 1995.The author is grateful to Professor V. A. Dorokhov, Professor V. P. Litvinov, and researchers from the laboratories of N. D. Zelinsky Institute of Organic Chemistry headed by them, who participated in joint studies.The work was carried out with financial support from the International Science Foundation (Grant No. MHYOO).  相似文献   
149.
Asymptotic methods for contact problems are expounded. Some typical integral equations are considered  相似文献   
150.
We consider a class of Markov decision processes withfinite state and action spaces which, essentially, is determined by the following condition: The state space isirreducible under the action of any stationary policy. However, except by this restriction, the transition law iscompletely unknown to the controller. In this context, we find a set of policies under which thefrequency estimators of the transition law are strongly consistent and then, this result is applied to constructadaptive asymptotically discount-optimal policies.Dedicated to Professor Truman O. Lewis, on the occasion of his sixtieth birthdayThis research was supported in part by the Third World Academy of Sciences (TWAS) under Grant TWAS RG MP 898-152, and in part by the Consejo Nacional de Ciencia y Tecnología (CONACYT) under Grant A128CCOEO550 (MT-2).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号