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   2206篇
  免费   42篇
  国内免费   24篇
管理学   184篇
民族学   8篇
人口学   24篇
丛书文集   107篇
理论方法论   64篇
综合类   1338篇
社会学   72篇
统计学   475篇
  2024年   5篇
  2023年   16篇
  2022年   18篇
  2021年   22篇
  2020年   33篇
  2019年   51篇
  2018年   64篇
  2017年   91篇
  2016年   69篇
  2015年   64篇
  2014年   131篇
  2013年   251篇
  2012年   167篇
  2011年   176篇
  2010年   127篇
  2009年   111篇
  2008年   125篇
  2007年   108篇
  2006年   93篇
  2005年   70篇
  2004年   56篇
  2003年   31篇
  2002年   44篇
  2001年   56篇
  2000年   42篇
  1999年   38篇
  1998年   26篇
  1997年   27篇
  1996年   23篇
  1995年   18篇
  1994年   18篇
  1993年   22篇
  1992年   17篇
  1991年   11篇
  1990年   7篇
  1989年   11篇
  1988年   9篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1981年   5篇
  1980年   1篇
  1979年   1篇
  1977年   2篇
排序方式: 共有2272条查询结果,搜索用时 7 毫秒
1.
Modeling cooperation among self-interested agents: a critique   总被引:2,自引:0,他引:2  
Herbert Gintis   《Journal of Socio》2004,33(6):695-714
This paper reviews recent attempts to model cooperation in groups of self-interested unrelated individuals. It concludes that no empirically plausible model has been developed, and the economist's quest for an explanation of human prosociality in terms of self-interested agents has not been successful. We show that the equilibrium criteria employed in standard game-theoretic models have no attractive dynamic properties, and the mechanisms deployed in these models are not generally seen in empirical examples of cooperative groups. We also show that these models are not robust to plausible rates of signaling error and mutation. We present an alternative, involving strongly reciprocal agents, that satisfies all the requirements for a dynamically stable model of cooperation.  相似文献   
2.
讨论了用微量热法测定酶促反应的米氏常数,酶活性,表观速率常数及表观活化能等动力学参数的实验方法和测定原理.介绍了摩尔反应焓的测定和计算方法,并借助过渡状态理论,探讨了酶底复合过程的吉氏自由能、焓和熵等热力学函数值的测定和计算方法  相似文献   
3.
本文研究了原子价层轨道能与共价型分子氢化物中A-H键的振动频率v_(A-H)的关系,结果表明二者间有良好的线性关系,其计算式为: v_(A-H)=-a∑n_1E_1/∑n_1(A)+b (1) V_(A-H)=-c∑n_1E_1/∑n~(B)+d (2)利用上式计算的振动频率V_(A-H)值接近于文献值。从而验证了用韩长日方法计算电负性的合理性。  相似文献   
4.
单元弹性下蛛网理论模型的建立与证明   总被引:3,自引:0,他引:3  
通过对微观经济学蛛网理论的供求动态分析 ,建立了其单元弹性下的模型 ,并给出了严格的证明 ,从而为蛛网理论经济分析提供了理论基础  相似文献   
5.
本文计及表面光学声子的作用以及像电荷的作用,采用变分方法对一些材料外表面束缚极化子的基态能量和自陷能作了数值计算,并对结果进行了讨论,发现:对于Ⅰ—Ⅶ、Ⅱ—Ⅵ,Ⅲ—Ⅴ化合物的外表面,均可形成稳定的束缚极化子,且由于表面光学声子的作用,使这一杂质态更加稳定。  相似文献   
6.
Summary An increase in fish mortality due to fishing can theoretically change the growth and reproduction of fish populations from the viewpoint of adaptation. We address the issue of how an iteroparous fish should convert surplus energy into somatic growth and reproduction at each age under given conditions of mortality. A model of life history, which maximizes the net reproductive rate using the discrete maximum principle, is improved employing a new relationship between body weight and surplus energy which we have recently proposed. The model is applied to the North Sea plaicePleuronectes platessa, for which it has been reported that the average length of young fish had increased whereas that of old ones had decreased for some decades. Although the model cannot directly explain the former phenomenon, the two phenomena can be interpreted as a change in the optimal life history due mainly to an increase in mortality.  相似文献   
7.
The L1 and L2-errors of the histogram estimate of a density f from a sample X1,X2,…,Xn using a cubic partition are shown to be asymptotically normal without any unnecessary conditions imposed on the density f. The asymptotic variances are shown to depend on f only through the corresponding norm of f. From this follows the asymptotic null distribution of a goodness-of-fit test based on the total variation distance, introduced by Györfi and van der Meulen (1991). This note uses the idea of partial inversion for obtaining characteristic functions of conditional distributions, which goes back at least to Bartlett (1938).  相似文献   
8.
Ranked set sampling is a sampling approach that leads to improved statistical inference in situations where the units to be sampled can be ranked relative to each other prior to formal measurement. This ranking may be done either by subjective judgment or according to an auxiliary variable, and it need not be completely accurate. In fact, results in the literature have shown that no matter how poor the quality of the ranking, procedures based on ranked set sampling tend to be at least as efficient as procedures based on simple random sampling. However, efforts to quantify the gains in efficiency for ranked set sampling procedures have been hampered by a shortage of available models for imperfect rankings. In this paper, we introduce a new class of models for imperfect rankings, and we provide a rigorous proof that essentially any reasonable model for imperfect rankings is a limit of models in this class. We then describe a specific, easily applied method for selecting an appropriate imperfect rankings model from the class.  相似文献   
9.
分析了当前我国企业海外能源投资所面临的国际法制困境,指出我国政府应积极行动,力求与国外签订有利于我国企业海外能源投资的能源合作双边协定,并参与区域性及全球性有关国际投资、能源合作规则的制定,从而为企业海外能源投资营造有利的国际法制环境。  相似文献   
10.
多项式零点问题的证明,已见于若干学报或教材.其方法可谓多种多样,但显复杂.本文先将Rolle定理加以推广,称之为“广义Rolle定理”,然后借助于该定理,证明一类著名的多项式零点值问题.  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