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   21868篇
  免费   596篇
  国内免费   3篇
管理学   2598篇
民族学   127篇
人才学   6篇
人口学   2058篇
丛书文集   130篇
教育普及   2篇
理论方法论   1937篇
现状及发展   1篇
综合类   310篇
社会学   10702篇
统计学   4596篇
  2023年   116篇
  2021年   114篇
  2020年   339篇
  2019年   557篇
  2018年   548篇
  2017年   795篇
  2016年   538篇
  2015年   432篇
  2014年   530篇
  2013年   3880篇
  2012年   759篇
  2011年   669篇
  2010年   522篇
  2009年   519篇
  2008年   564篇
  2007年   563篇
  2006年   517篇
  2005年   471篇
  2004年   466篇
  2003年   430篇
  2002年   456篇
  2001年   542篇
  2000年   444篇
  1999年   445篇
  1998年   366篇
  1997年   336篇
  1996年   339篇
  1995年   338篇
  1994年   309篇
  1993年   297篇
  1992年   341篇
  1991年   339篇
  1990年   318篇
  1989年   310篇
  1988年   281篇
  1987年   265篇
  1986年   256篇
  1985年   292篇
  1984年   285篇
  1983年   268篇
  1982年   212篇
  1981年   186篇
  1980年   205篇
  1979年   211篇
  1978年   176篇
  1977年   163篇
  1976年   140篇
  1975年   132篇
  1974年   114篇
  1972年   91篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
81.
82.
Using data from 8 random assignment studies and employing meta‐analytic techniques, this article provides systematic evidence that welfare and work policies targeted at low‐income parents have small adverse effects on some school outcomes among adolescents ages 12 to 18 years at follow‐up. These adverse effects were observed mostly for school performance outcomes and occurred in programs that required mothers to work or participate in employment‐related activities and those that encouraged mothers to work voluntarily. The most pronounced negative effects on school outcomes occurred for the group of adolescents who had a younger sibling, possibly because of the increased home and sibling care responsibilities they assumed as their mothers increased their employment.  相似文献   
83.
Not having a variance estimator is a seriously weak point of a sampling design from a practical perspective. This paper provides unbiased variance estimators for several sampling designs based on inverse sampling, both with and without an adaptive component. It proposes a new design, which is called the general inverse sampling design, that avoids sampling an infeasibly large number of units. The paper provide estimators for this design as well as its adaptive modification. A simple artificial example is used to demonstrate the computations. The adaptive and non‐adaptive designs are compared using simulations based on real data sets. The results indicate that, for appropriate populations, the adaptive version can have a substantial variance reduction compared with the non‐adaptive version. Also, adaptive general inverse sampling with a limitation on the initial sample size has a greater variance reduction than without the limitation.  相似文献   
84.
Vulnerability and Agenda: Context and Process in Project Management   总被引:1,自引:0,他引:1  
This paper explores how the project management role is conditioned by the context in which change is progressed. The argument draws on Pettigrew's (1985, 1987) contextual and processual view of change, a view which does not clarify the management implications of contextual variation. Using data from a two-stage research design combining diary and survey methods, four context dimensions are identified, concerning ‘interlocking’, ‘shifting sands’, ‘ownership’ and ‘senior management view’. For analytical purposes, two extreme contexts are characterized as exposing the project manager to high and low levels of ‘vulnerability’ respectively. Project management literature typically offers a rational-linear account of change, and concentrates on ‘content’ and ‘control’ agendas, concerning technical expertise on the one hand, and planning, budgeting and monitoring techniques on the other. Sociological analyses reveal the limitations of the rational-linear account, and focus on the political and cultural dimensions of the ‘process’ agenda. The data suggest how contextual variation affects the relative priority of these agendas. The management implications of these findings are explored, for project management selection, career progression, and the development of diagnostic skills and ‘agenda management’ strategies.  相似文献   
85.
1. Most diagnosed cases of tardive dyskinesia (TD) are mildly inconvenient to the patient, but some can be severe or life-threatening. The primary goal of intervention should be early identification of abnormal movements related to TD and the prescribing of an appropriate medication regimen. 2. Unless specific training occurs and a specific monitoring system is in place, TD movements may be missed. However, not all movements are necessarily related to TD. 3. Although screening and monitoring are valuable, nothing is more important than prevention. New medications must be developed that do not carry the risk of TD, and other approaches to treat TD must be developed.  相似文献   
86.
Australian secondary school students from three Year levels were asked to rate the danger involved in various uses of alcohol, tobacco, inhalants, marijuana and other illicit drugs. These ratings were then factor analyzed for each Year level. The results showed a more refined discrimination among the older students, with type of drug and frequency of use being important considerations. Familiarity was a major consideration for the younger students. The cognitive factors derived from the data are consistent with expectations based on the gateway theory of drug use.  相似文献   
87.
The Dutch reformed individual income tax was implemented on January 1, 1990. The rationale of the tax reform is described, and the major changes are discussed and compared to developments abroad. As far as rate reduction and base-broadening are concerned, the Netherlands has followed the trend in international tax reforms. The Dutch tax reform process, however, focussed more on simplification than in other Western countries.  相似文献   
88.
89.
In the development of many diseases there are often associated random variables which continuously reflect the progress of a subject towards the final expression of the disease (failure). At any given time these processes, which we call stochastic covariates, may provide information about the current hazard and the remaining time to failure. Likewise, in situations when the specific times of key prior events are not known, such as the time of onset of an occult tumour or the time of infection with HIV-1, it may be possible to identify a stochastic covariate which reveals, indirectly, when the event of interest occurred. The analysis of carcinogenicity trials which involve occult tumours is usually based on the time of death or sacrifice and an indicator of tumour presence for each animal in the experiment. However, the size of an occult tumour observed at the endpoint represents data concerning tumour development which may convey additional information concerning both the tumour incidence rate and the rate of death to which tumour-bearing animals are subject. We develop a stochastic model for tumour growth and suggest different ways in which the effect of this growth on the hazard of failure might be modelled. Using a combined model for tumour growth and additive competing risks of death, we show that if this tumour size information is used, assumptions concerning tumour lethality, the context of observation or multiple sacrifice times are no longer necessary in order to estimate the tumour incidence rate. Parametric estimation based on the method of maximum likelihood is outlined and is applied to simulated data from the combined model. The results of this limited study confirm that use of the stochastic covariate tumour size results in more precise estimation of the incidence rate for occult tumours.  相似文献   
90.
Dental caries in children is now recognized as a preventable disease. The use of fluoride and sealants has produced a major reduction in caries prevalence among school aged children in the United States and other countries. A portion of the child population who are educationally and socioeconomically disadvantaged are not fully receiving these benefits. Public policy, insurance and medicaid groups must be made aware of these preventative measures and strategies developed to implement them.  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