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   373篇
  免费   8篇
管理学   68篇
民族学   1篇
人口学   25篇
理论方法论   30篇
综合类   1篇
社会学   218篇
统计学   38篇
  2019年   5篇
  2018年   9篇
  2017年   6篇
  2016年   7篇
  2015年   3篇
  2014年   6篇
  2013年   87篇
  2012年   19篇
  2011年   7篇
  2010年   2篇
  2009年   8篇
  2008年   5篇
  2007年   11篇
  2006年   7篇
  2005年   8篇
  2004年   8篇
  2003年   5篇
  2002年   6篇
  2001年   11篇
  2000年   7篇
  1999年   5篇
  1998年   7篇
  1997年   6篇
  1996年   5篇
  1995年   7篇
  1994年   10篇
  1993年   8篇
  1992年   8篇
  1991年   8篇
  1990年   9篇
  1989年   2篇
  1988年   6篇
  1987年   6篇
  1986年   6篇
  1985年   4篇
  1984年   6篇
  1983年   5篇
  1982年   5篇
  1981年   7篇
  1980年   6篇
  1979年   4篇
  1978年   2篇
  1977年   5篇
  1976年   4篇
  1975年   3篇
  1973年   2篇
  1972年   2篇
  1970年   1篇
  1968年   1篇
  1964年   1篇
排序方式: 共有381条查询结果,搜索用时 15 毫秒
31.
Ralph H Sprague  Jr  Hugh J Watson 《Omega》1976,4(6):657-671
Just recently, information systems with rather unique characteristics have begun to emerge. These systems usually referred to as Decision Support Systems, feature decision models, a data base and the decision maker as subsystems and are specifically oriented to supporting decision making. This article examines Decision Support Systems and their application to banks.  相似文献   
32.
Two assumptions used in risk assessment are investigated: (1) the assumption of fraction of lifetime dose rate assumes that the risk from a fractional lifetime exposure at a given dose rate is equal to the risk from full lifetime exposure at that same fraction of the given dose rate; (2) the assumption of fraction of lifetime risk assumes that the risk from a fractional lifetime exposure at a given dose rate is equal to that same fraction of the risk from full lifetime exposure at the same dose rate. These two assumptions are equivalent when risk is a linear function of dose. Thus both can be thought of as generalizations of the assumption that cancer risk is proportional to the total accumulated lifetime dose (or average daily dose), which is often made to assess the risk from short-term exposures. In this paper, the age-specific cumulative hazard functions are derived using the two-stage model developed by Moolgavkar, Venzon, and Knudson for situations when the exposure occurs during a single period or a single instant. The two assumptions described above are examined for three types of carcinogens, initiator, completer, and promoter, in the context of the model. For initiator and completer, these two assumptions are equivalent in the low-dose region; for a promoter, using the fraction of lifetime risk assumption is generally more conservative than that of the fraction of lifetime dose rate assumption. Tables are constructed to show that the use of either the fraction of lifetime dose rate assumption or the fraction lifetime risk assumption can both underestimate and overestimate the true risk for the three types of carcinogens.  相似文献   
33.
A nonparametric estimator of the probability distribution of time-to-tumor is incorporated into an algorithm for calculating linearly extrapolated dosage limits from an animal carcino-genesis bioassay. The procedure is illustrated with tumor data from a mouse bioassay with 2-acetylaminofluorene. Extrapolated dosage limits for an excess risk of 10-6 differ by only a factor of 2 across the six replicates of the experiment.  相似文献   
34.
35.
It is twenty-five years since the passing of Karen Horney. A productive professional who dared to differ with Sigmund Freud, Horney has written clearly and brilliantly, almost in a "common-sensical" style, about the development of neurotic character structure and interpersonal relationships. Her stress on cultural, societal, and family influences has strong implications for theorists and professional practitioners in the field of marriage and the family. Her optimistic view of human nature, especially as it relates to the possibility for change at all ages and stages, should be a continuous inspiration to those helping disturbed individuals, relationships, marriages, and families. This is a tribute to a rare, worthy human being.  相似文献   
36.
Abstract Previous models of community satisfaction and attachment have not included personal economic attitudes and behaviors as independent variables. Their inclusion is theoretically justified when residents of communities are viewed as consumers in a larger social/economic context first and residents of a particular community second. As locally-oriented economic processes—once part of the community experience—were removed to nonlocal markets, local economic and demographic attributes became less important to rural residents' experience of community. In two rural communities with extreme scores on a service center viability index, satisfaction with employment and location of employment are important predictors.  相似文献   
37.
In any analysis of a decision problem involving public risks, ethical implications are introduced. In some cases, these ethical implications may be introduced simply because an analysis is being done. Additional ethical implications may be inherently part of the methodology being utilized or introduced into the specific analysis of the decision problem. In this paper, we investigate where and how ethical implications enter when using the methodology of decision analysis to examine problems involving public risks. We conclude that the methodology of decision analysis is sufficiently robust to allow for numerous different ethical viewpoints to be accounted for in any specific analysis. Stated alternatively, decision analyses of public risks can be conducted in a manner consistent with utilitarianism, deontological theories, libertarianism, egalitarianism, and so forth. However, any specific analysis has embedded within it numerous ethical implications. This suggests that the careful ethical scrutiny of analyses involving the methodology of decision analysis should be placed on the specific application and not on the methodology per se or on the fact that an analysis is undertaken.  相似文献   
38.
The area under the receiver operating characteristic curve (AUC) is the most commonly reported measure of discrimination for prediction models with binary outcomes. However, recently it has been criticized for its inability to increase when important risk factors are added to a baseline model with good discrimination. This has led to the claim that the reliance on the AUC as a measure of discrimination may miss important improvements in clinical performance of risk prediction rules derived from a baseline model. In this paper we investigate this claim by relating the AUC to measures of clinical performance based on sensitivity and specificity under the assumption of multivariate normality. The behavior of the AUC is contrasted with that of discrimination slope. We show that unless rules with very good specificity are desired, the change in the AUC does an adequate job as a predictor of the change in measures of clinical performance. However, stronger or more numerous predictors are needed to achieve the same increment in the AUC for baseline models with good versus poor discrimination. When excellent specificity is desired, our results suggest that the discrimination slope might be a better measure of model improvement than AUC. The theoretical results are illustrated using a Framingham Heart Study example of a model for predicting the 10-year incidence of atrial fibrillation.  相似文献   
39.
Abstract

Research involving administrative healthcare data to study patient outcomes requires the investigator to account for the patient’s disease burden in order to reduce the potential for biased results. Here we develop a comorbidity summary score based on variable importance measures derived from several statistical and machine learning methods and show it has superior predictive performance to the Elixhauser and Charlson indices when used to predict 1-year, 5-year, and 10-year mortality. We used two large Veterans Administration cohorts to develop and validate the summary score and compared predictive performance using the area under ROC curve (AUC) and the Brier score.  相似文献   
40.
The North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT) have focused attention on risk assessment of potential insect, weed, and animal pests and diseases of livestock. These risks have traditionally been addressed through quarantine protocols ranging from limits on the geographical areas from which a product may originate, postharvest disinfestation procedures like fumigation, and inspections at points of export and import, to outright bans. To ensure that plant and animal protection measures are not used as nontariff trade barriers, GATT and NAFTA require pest risk analysis (PRA) to support quarantine decisions. The increased emphasis on PRA has spurred multiple efforts at the national and international level to design frameworks for the conduct of these analyses. As approaches to pest risk analysis proliferate, and the importance of the analyses grows, concerns have arisen about the scientific and technical conduct of pest risk analysis. In January of 1997, the Harvard Center for Risk Analysis (HCRA) held an invitation-only workshop in Washington, D.C. to bring experts in risk analysis and pest characterization together to develop general principles for pest risk analysis. Workshop participants examined current frameworks for PRA, discussed strengths and weaknesses of the approaches, and formulated principles, based on years of experience with risk analysis in other setting and knowledge of the issues specific to analysis of pests. The principles developed highlight the both the similarities of pest risk analysis to other forms of risk analysis, and its unique attributes.  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