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   1685篇
  免费   132篇
  2023年   13篇
  2022年   22篇
  2021年   26篇
  2020年   61篇
  2019年   63篇
  2018年   83篇
  2017年   72篇
  2016年   98篇
  2015年   73篇
  2014年   78篇
  2013年   212篇
  2012年   122篇
  2011年   97篇
  2010年   81篇
  2009年   75篇
  2008年   94篇
  2007年   65篇
  2006年   46篇
  2005年   42篇
  2004年   65篇
  2003年   42篇
  2002年   32篇
  2001年   18篇
  2000年   20篇
  1999年   14篇
  1998年   15篇
  1997年   8篇
  1994年   7篇
  1993年   6篇
  1992年   7篇
  1991年   5篇
  1990年   5篇
  1989年   4篇
  1988年   8篇
  1987年   5篇
  1986年   7篇
  1984年   6篇
  1983年   4篇
  1982年   5篇
  1981年   6篇
  1980年   10篇
  1979年   7篇
  1978年   6篇
  1976年   10篇
  1975年   5篇
  1974年   7篇
  1973年   6篇
  1972年   5篇
  1971年   6篇
  1966年   5篇
排序方式: 共有1817条查询结果,搜索用时 15 毫秒
1.
There is substantial evidence of detrimental psychological sequelae following disasters, including terrorist attacks. The effect of these events on extreme responses such as suicide, however, is unclear. We tested competing hypotheses about such effects by employing autoregressive integrated moving average techniques to model the impact of September 11 and the Oklahoma City bombing on monthly suicide counts at the local, state, and national level. Unlike prior studies that provided conflicting evidence, rigorous time series techniques revealed no support for an increase or decrease in suicides following these events. We conclude that while terrorist attacks produce subsequent psychological morbidity and may affect self and collective efficacy well beyond their immediate impact, these effects are not strong enough to influence levels of suicide mortality.  相似文献   
2.
3.
4.
5.
6.
7.
This article attempts to identify some cognitive tendencies involved in analogical forecasting of the outcomes of medical treatment. Sixty-one medical doctors were involved in two experimental tasks concerned with prediction of the outcomes of a new medical treatment when the result with a first patient was known to be either negative or positive. The same subjects were also tested by the Short Optimism/Pessimism Questionnaire (SO/PQ) to explore relationships between life attitude and the cognitive tendencies observed in the experiment. The following findings were reported: (1) The first step of forecasting was recognized as a Data Evaluation Process (DEP), where the physician decides if the given data are sufficient to forecast the result of the same treatment with a new patient. (2) Two cognitive tendencies were identified: non-data-suggested tendency—drawing a conclusion opposite to the data given; and data-suggested tendency—drawing an optimistic conclusion when forecasting from “positive” data and a pessimistic conclusion when forecasting from “negative” data. The second tendency appeared to be dominant; however, the “positive” data created a stronger atmosphere to draw conclusions on a negative outcome. (3) It was stated that analogical forecasting involves two integrated processes, i.e., concluding and asserting. If the integration process is not complete, the subject is drawing analogical conclusions with a low confidence. (4) An optimistic life attitude appeared to be an important factor in determining analogical forecasting.  相似文献   
8.
The goal of this study was to examine how the kinematics of reciprocal aiming movements were affected by both the objective of the movement and the constraints operating on that movement. In Experiment 1, the objective of the movement was indirectly manipulated by capitalizing on the fact that subjects determine their own accuracy and speed limits, despite uniform task instructions to move as quickly and accurately as possible. A Fitts' type reciprocal aiming paradigm was employed, in which 69 subjects were asked to move a stylus repetitively between two spatially separated targets. Four target widths were orthogonally combined with four movement amplitudes, resulting in 16 conditions. Movements were made on an X-Y digitizing tablet. Based on the mean variable error produced on both targets, subjects were differentiated post hoc into three movement objective groups: speed, accuracy, and speed-plus-accuracy. Kinematic analyses revealed that the programming and execution of movements were systematically influenced by both the movement objective and the movement constraints. That is, movement time, peak velocity, dwell time, acceleration and deceleration time, normalized acceleration and normalized deceleration varied systematically as a function of both the speed-accuracy movement objective and the movement constraints of target size and movement distance. Moreover, the consequences of changing the constraints of the movement were affected by an interaction with the objective of the movement. In Experiment 2, the objective of the movement was directly manipulated by varying speed and/or accuracy instructions to subjects. The basic results of Experiment 1 were substantiated. Overall, the results were consistent with the view that motor control is dependent upon sensory consequences.  相似文献   
9.
In the paper there are introduced and discussed the concepts of an indexed category with quantifications and a higher level indexed category to present an algebraic characterization of some version of Martin-Löf Type Theory. This characterization is given by specifying an additional equational structure of those indexed categories which are models of Martin-Löf Type Theory. One can consider the presented characterization as an essentially algebraic theory of categorical models of Martin-Löf Type Theory. The paper contains a construction of an indexed category with quantifications from terms and types of the language of Martin-Löf Type Theory given in the manner of Troelstra [11]. The paper contains also an inductive definition of a valuation of these terms and types in an indexed category with quantifications.  相似文献   
10.
The present study was conducted to examine the hypothesis that compliant chronically ill patients, typically described as adjusted, reinforce more positive social environments using behavioral controls than noncompliant patients, typically described as maladjusted. Specifically, it is hypothesized that diet-compliant chronic hemodialysis patients emit significnatly more active involvement-in-treatment behaviors and more social behaviors than diet-noncompliant chronic hemodialysis patients. Subjects, who ranged in age from 30 to 77 years, were outpatients at a kidney center. Behavioral observations were conducted to assess the occurrence or frequency of (1) four involvement-in-treatment behaviors that are routinely taught to all patients and (2) two social behaviors, which were patient verbalizations and smiles. The results showed that compliant patients emitted significantly more involvement-in-treatment behaviors and smiles than noncompliant patients. Results support the proposed control framework that compliant, in contrast to non-compliant, chronically ill patients have recourse through positive behavioral controls when adjusting to the stresses of illness. It was proposed that through these controls, compliant patients reinforce positive environments rather than simply respond to life circumstances as given.  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