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   8417篇
  免费   211篇
管理学   1219篇
民族学   35篇
人口学   810篇
丛书文集   30篇
理论方法论   667篇
综合类   111篇
社会学   3737篇
统计学   2019篇
  2021年   47篇
  2020年   140篇
  2019年   187篇
  2018年   257篇
  2017年   333篇
  2016年   235篇
  2015年   151篇
  2014年   210篇
  2013年   1407篇
  2012年   282篇
  2011年   262篇
  2010年   193篇
  2009年   186篇
  2008年   164篇
  2007年   204篇
  2006年   174篇
  2005年   176篇
  2004年   160篇
  2003年   152篇
  2002年   155篇
  2001年   202篇
  2000年   196篇
  1999年   174篇
  1998年   132篇
  1997年   130篇
  1996年   127篇
  1995年   106篇
  1994年   105篇
  1993年   98篇
  1992年   140篇
  1991年   119篇
  1990年   119篇
  1989年   111篇
  1988年   97篇
  1987年   90篇
  1986年   95篇
  1985年   108篇
  1984年   114篇
  1983年   124篇
  1982年   100篇
  1981年   88篇
  1980年   85篇
  1979年   94篇
  1978年   91篇
  1977年   80篇
  1976年   67篇
  1975年   67篇
  1974年   58篇
  1973年   58篇
  1971年   49篇
排序方式: 共有8628条查询结果,搜索用时 187 毫秒
171.
This article outlines the potential in the fishing industry viewed from the present. The author argues that current methods are still relatively inefficient and that increases of 50–100 per cent can be expected in the next 10–20 years. Further that these larger catches can contribute markedly to world protein requirements. The article includes consideration of system fishing and concludes with a picture of the British fishing industry being among the most advanced in the world.  相似文献   
172.
Summary In Matlab Bazaar Thana the Cholera Research Laboratory has registered the births, deaths and migrations in a population of approximately 125,000 since 1966. Although this rural area was not the scene of any significant armed encounters, striking changes in birth and death rates were registered during and after the conflict. Birth rates did not change during the relatively brief period of the civil war, but a small decline was registered for one year after the war. Fertility rates which had been declining slightly and irregularly in the pre-war baseline period may have increased slightly during the war and fell substantially in all age groups in the year following the war. The crude death rate, which rose by 37 per cent during the war, was a very sensitive reflection of the administrative and economic problems. Overall infant mortality rose by only 15 per cent over pre-war levels because all of the increase was observed in the post-neo-natal component, which traditionally accounts for less than one-third of the total infant mortality in Bangladesh. Children and older adults accounted for the majority of excess deaths which were largely attributed to acute diarrhoeas and other gastro-intestinal causes. The death rate at ages 1-4 rose by 43 per cent and at ages 5-9 soared to 208 per cent above pre-war baseline rates. All increases in age-specific mortality rates fell to baseline levels during the year following the war, except the 5-9-year age group, in which rates continued to be high largely because of deaths due to dysentery.  相似文献   
173.
Summary Ledermann's one- and two-parameter model life tables are used in order to summarize and compare adult mortality estimates derived from parental survival data, and also to link parental survival with child survival data. The Ledermann models provide an alternative to the logit model used by Brass and Hill. Examination of life tables derived from actual child and adult mortality estimates reveals that although the two types of models yield similar overall levels of mortality, they show marked differences in the estimated patterns by sex and age. It has not been possible to disentangle completely how much of this divergence is due to the models themselves and how much to inadequacies in the data available. Finally, we question whether it is always wise to establish a full life table from child and adult mortality estimates when these are based on data which refer to different periods of exposure to the risk of dying, without allowance for possible distortions resulting from mortality change.  相似文献   
174.
Data from an island-wide probability sample of 4119 Barbadian females aged 16-50 were used to study whether there has been an intergenerational fertility decline between the respondents and their mothers. The fertility of the respondents, all from the low or lower middle class, was significantly lower than that of their mothers. However, the size of the family of procreation was seen to be positively related to the size of the family of orientation; i.e., those from large families tended to have large families and vice versa. There was, however, a regression to the mean. There were no differences between women from small and large families as to fertility norms, age at 1st use of contraceptives, or actual practice of contraception. Women from small families did tend to enter sexual relationships and get pregnant at a later age. The women from small families were better educated, earned higher incomes, and had higher status occupations, all factors which might have influenced their fertility. Women from larger families cited higher numbers for both small and large families than did the women from small families. This indicates a perceptual difference which was, in turn, related to fertility differences.  相似文献   
175.
The matching identification problem (MIP) is a combinatoric search problem related to the fields of learning from examples, boolean functions, and knowledge acquisition. The MIP involves identifying a single “goal” item from a large set of items. Because there is commonly a cost associated with evaluating each guess, the goal item should be identified in as few guesses as possible. As in most search problems, the items have a similar structure, which allows an evaluation of each guessed item. In other words, each guessed item elicits partial information about the goal item, i.e. how similar the guess is to the goal. With this information the goal is more quickly identified.The unordered MIP has been studied by Mehrez and Steinberg (ORSA J. Comput. 7 (1995) 211) in which they proposed two different types of algorithms. The purpose of the present paper is to suggest an improved Spanning Heuristic algorithm. Its improvement increases as the problem size increases. Further results and comparisons are derived for the unordered and ordered cases.This research shows that when the search space is very large, it is better to inquire from items that are known not to be the goal (they have been ruled out by previous guesses), for the purpose of acquiring more information about the goal. As the search space is narrowed, it is better to guess items that have not been ruled out.  相似文献   
176.
177.
This paper reviews the state of the field of the sub-disciplines within UK management research, based upon the submissions of 94 UK higher education institutions to the Business and Management Studies Panel in the UK's 2001 Research Assessment Exercise (RAE). It offers observations on the UK model of the assessment of quality in, and funding of, research conducted in publicly funded higher education institutions.  相似文献   
178.
This study examines a key component of environmental risk communication; trust and credibility. The study was conducted in two parts. In the first part, six hypotheses regarding the perceptions and determinants of trust and credibility were tested against survey data. The hypotheses were supported by the data. The most important hypothesis was that perceptions of trust and credibility are dependent on three factors: perceptions of knowledge and expertise; perceptions of openness and honesty; and perceptions of concern and care. In the second part, models were constructed with perceptions of trust and credibility as the dependent variable. The goal was to examine the data for findings with direct policy implications. One such finding was that defying a negative stereotype is key to improving perceptions of trust and credibility.  相似文献   
179.
Editorial     
Ohne Zusammenfassung  相似文献   
180.
Consider the problem of partitioning n nonnegative numbers into p parts, where part i can be assigned ni numbers with ni lying in a given range. The goal is to maximize a Schur convex function F whose ith argument is the sum of numbers assigned to part i. The shape of a partition is the vector consisting of the sizes of its parts, further, a shape (without referring to a particular partition) is a vector of nonnegative integers (n1,..., np) which sum to n. A partition is called size-consecutive if there is a ranking of the parts which is consistent with their sizes, and all elements in a higher-ranked part exceed all elements in the lower-ranked part. We demonstrate that one can restrict attention to size-consecutive partitions with shapes that are nonmajorized, we study these shapes, bound their numbers and develop algorithms to enumerate them. Our study extends the analysis of a previous paper by Hwang and Rothblum which discussed the above problem assuming the existence of a majorizing shape. This research is partially supported by ROC National Science grant NSC 92-2115-M-009-014.  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