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   9489篇
  免费   234篇
管理学   1412篇
民族学   52篇
人才学   1篇
人口学   953篇
丛书文集   28篇
理论方法论   752篇
综合类   134篇
社会学   4077篇
统计学   2314篇
  2022年   57篇
  2021年   83篇
  2020年   185篇
  2019年   247篇
  2018年   347篇
  2017年   399篇
  2016年   301篇
  2015年   184篇
  2014年   282篇
  2013年   1575篇
  2012年   349篇
  2011年   302篇
  2010年   236篇
  2009年   225篇
  2008年   193篇
  2007年   221篇
  2006年   197篇
  2005年   193篇
  2004年   173篇
  2003年   162篇
  2002年   170篇
  2001年   215篇
  2000年   202篇
  1999年   183篇
  1998年   143篇
  1997年   137篇
  1996年   139篇
  1995年   117篇
  1994年   109篇
  1993年   99篇
  1992年   150篇
  1991年   123篇
  1990年   118篇
  1989年   112篇
  1988年   99篇
  1987年   93篇
  1986年   96篇
  1985年   111篇
  1984年   114篇
  1983年   125篇
  1982年   98篇
  1981年   88篇
  1980年   86篇
  1979年   95篇
  1978年   92篇
  1977年   80篇
  1976年   67篇
  1975年   68篇
  1974年   59篇
  1973年   59篇
排序方式: 共有9723条查询结果,搜索用时 265 毫秒
131.
Immigration has long been a national and state concern. The 1989 Legalized Population Survey (LPS-1) collected data on illegal immigrants to the US who subsequently became legalized aliens under the provisions of the 1986 Immigration Reform and Control Act. These data are used in a study assessing whether undocumented male and female immigrants improve their earnings and occupational status over time and the extent of variation in occupational status and mobility by gender and region. The data indicate that both undocumented men and women, on average, improved their earnings and occupational status between their first jobs in the US and their jobs just before applying for legalization under the 1986 Immigration Reform and Control Act. However, the earnings, occupational status, and occupational mobility of men were greater than for women.  相似文献   
132.
The Spanish Civil War (1936—1939) interrupted the evolution and development of social pedagogy, which in Spain had reached similar levels as in other European countries. This was followed by a period when Spain was isolated from developments in social welfare and the changes that go along with the economic and social transformations of cities and give rise to community action, self-help and popular education programmes. The reinstatement of democracy and of new City Councils that are genuinely devoted to solve the problems of the population are the starting point for new social services, that is for social work and social pedagogy. Initially it was practical work that gave an answer to emerging demand, followed by theoretical analysis and efforts of conceptualisation. The professionals and later the universities lead the debate on methodology. The interest and involvement of the universities increased as the Diploma in Social Education was introduced as a new university degree.  相似文献   
133.
LetX1,X2, ..., be real-valued random variables forming a strictly stationary sequence, and satisfying the basic requirement of being either pairwise positively quadrant dependent or pairwise negatively quadrant dependent. LetF^ be the marginal distribution function of theXips, which is estimated by the empirical distribution functionFn and also by a smooth kernel-type estimateFn, by means of the segmentX1, ...,Xn. These estimates are compared on the basis of their mean squared errors (MSE). The main results of this paper are the following. Under certain regularity conditions, the optimal bandwidth (in the MSE sense) is determined, and is found to be the same as that in the independent identically distributed case. It is also shown thatn MSE(Fn(t)) andnMSE (F^n(t)) tend to the same constant, asn→∞ so that one can not discriminate be tween the two estimates on the basis of the MSE. Next, ifi(n) = min {k∈{1, 2, ...}; MSE (Fk(t)) ≤ MSE (Fn(t))}, then it is proved thati(n)/n tends to 1, asn→∞. Thus, once again, one can not choose one estimate over the other in terms of their asymptotic relative efficiency. If, however, the squared bias ofF^n(t) tends to 0 sufficiently fast, or equivalently, the bandwidthhn satisfies the requirement thatnh3n→ 0, asn→∞, it is shown that, for a suitable choice of the kernel, (i(n) ?n)/(nhn) tends to a positive number, asn→∞ It follows that the deficiency ofFn(t) with respect toF^n(t),i(n) ?n, is substantial, and, actually, tends to ∞, asn→∞. In terms of deficiency, the smooth estimateF^n(t) is preferable to the empirical distribution functionFn(t)  相似文献   
134.
In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures.  相似文献   
135.
We explore how natural selection acts upon genes for cooperation, altruism and selfishness in an prisoner's dilemma played by family members. A key parameter determining behavior is that parents and children have different expectations of future offspring. Examining asexual and sexually reproducing populations we show that which strategy of cooperation and defection proves be stable depends on the relative reproduction potential of the players and what proportion of the population is young. "Rotten kids" with altruistic parents can be a stable outcome where reproductive success is the goal, and natural selection may lead individuals to care about their unborn progeny. (JEL D10, H31)  相似文献   
136.
Are you prepared to ride the waves of change? Will you be ready when the pink slip arrives? Health care executives who can jump a little higher and run a little faster will go further in the draft. Those of you who are prepared for change will always be appealing to recruiters and prospective employers. How can you ride these turbulent waves and not capsize? This article explores some suggestions for positioning yourself: Proper positioning with the inevitable changes in mind will help you move your career in a forward direction.  相似文献   
137.
Medical practices historically have not been examined in terms of their organizational structures and of the appropriateness of their structures for survival as business entities. In this paper, we propose a model for the typical medical practice and discuss its fit with current organizational theory. It is apparent that the medical practice organization does not fit with the demands of a rapidly changing and complex environment. To survive and grow, the medical practice organization must align itself with others that have an interest and stake in the health care system, develop teamwork among physicians, bridge the gap between physicians and others in the organization, and recognize that the work done in the organization depends on other components of the organization.  相似文献   
138.
This study examines the impact of mandatory seat belt laws on fatal and incapacitating injury rates in the states. Annual data for all 50 states for the period 1975-1991 are used. Pooled time series analysis is employed. The general conclusion that emerges from this analysis is that seat belt laws significantly impact state fatal injury rates. Primary enforcement and all-seat coverage provisions appear to be particularly effective in reducing fatality rates.  相似文献   
139.
The need for long-term care is driven both by the growth of the elderly population and changes in the age relations of morbidity, disability, and mortality. Data show these relations changed in the U.S. elderly population from 1982 to 1989. Chronic disability prevalence declined between the 1982 and 1989 U.S. National Long Term Care Surveys. Among those impaired, many persons using personal assistance to meet their needs shifted to the use of assisted housing and special equipment. The relation of these trends to other changes--such as the increasing educational level of the elderly population--is examined to estimate how future changes in disability and morbidity may affect the demand for long-term care. Disabilities at specific times as well as their transition rates were examined to determine how long individuals need long-term care. The analyses suggest that, while the amount of long-term care services needed will increase rapidly, the types and amounts of services used by the U.S. elderly population will undergo significant change.  相似文献   
140.
SupposeL(X) is the law of a positive random variableX, andZ is positive and independent ofX. Admissible solution pairs (L(X),L(Z)) are sought for the in-law equation $\hat X \cong X o Z$ °Z, where $L\left( {\hat X} \right)$ is a weighted law constructed fromL(X), and ° is a binary operation which in some sense is increasing. The class of weights includes length biasing of arbitrary order. When ° is addition and the weighting is ordinary length biasing, the class of admissibleL(X) comprises the positive infinitely divisible laws. Examples are given subsuming all known specific cases. Some extensions for general order of length-biasing are discussed.  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