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   35961篇
  免费   650篇
  国内免费   2篇
  36613篇
  2020年   378篇
  2019年   518篇
  2018年   699篇
  2017年   768篇
  2016年   730篇
  2015年   534篇
  2014年   603篇
  2013年   2826篇
  2012年   1079篇
  2011年   1186篇
  2010年   745篇
  2009年   777篇
  2008年   1083篇
  2007年   1013篇
  2006年   903篇
  2005年   773篇
  2004年   728篇
  2003年   773篇
  2002年   700篇
  2001年   1232篇
  2000年   1209篇
  1999年   879篇
  1998年   419篇
  1997年   338篇
  1996年   321篇
  1995年   323篇
  1994年   327篇
  1993年   316篇
  1992年   731篇
  1991年   703篇
  1990年   665篇
  1989年   617篇
  1988年   588篇
  1987年   586篇
  1986年   547篇
  1985年   614篇
  1984年   479篇
  1983年   377篇
  1979年   467篇
  1978年   345篇
  1977年   329篇
  1975年   416篇
  1974年   422篇
  1973年   475篇
  1972年   384篇
  1971年   320篇
  1969年   328篇
  1968年   378篇
  1967年   334篇
  1966年   386篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
Previous cross-sectional field and laboratory research has provided mixed results as to whether recruiter characteristics and behaviors influence applicant reactions to employment opportunities. The present research was conducted to examine the effect of recruiter characteristics using a pre-post study design in a naturally occurring setting. In addition, the effects of several potential moderators on recruiter influence were tested. Results indicated that recruiter characteristics had an impact on perceived job attributes, regard for job and company, and likelihood of joining the company. There was little evidence that the effect of recruiter characteristics was moderated by selected applicant, job, or interviewer variables.  相似文献   
172.
Left sidedness and sleep difficulty: the alinormal syndrome   总被引:1,自引:1,他引:0  
Four indexes of laterality: handedness, footedness, eyedness, and earedness, were assessed in a sample of 1274 subjects. Left- and right-sided groups were compared on two aspects of self-reported sleep difficulty: trouble falling asleep and frequent night wakenings. The incidence of sleep difficulty was found to be elevated in the left-sided groups. The results are discussed in terms of a possible complex of behavioral deviations from the statistical norm, called the alinormal syndrome.  相似文献   
173.
174.
175.
Regional cerebral blood flow (rCBF) may be measured with inhalation techniques that use end-expired values of radioactivity to estimate the isotope concentration in arterial blood. These end-expired data are used as an input function in a mathematical equation to derive rCBF. End-expired air is assumed normally to be in equilibrium with the arterial blood at the alveolar surface of the lung during regular (passive) breathing; this assumption may not be valid during continuous phonation. We therefore have analyzed breathing (inhalation/exhalation) patterns and end-expired radioactivity (133Xe) during (1) speaking, (2) singing, and (3) humming of the national anthem, and also during (4) passive breathing. Statistically significant differences in breathing patterns were measured between a group of nonmusicians and two groups of musicians (singers) during the phonation tasks: The nonmusicians breathed more often (and more rapidly) and exhibited less variability in their breathing patterns than did the musicians. Notwithstanding these differences, the shapes of smoothed functions derived from the end-expired values were not influenced appreciably during phonation (except possibly during talking). The latter finding suggests that estimates of rCBF derived with these data should not be confounded seriously because of the continuous phonation.  相似文献   
176.
A long-term temporal component of working memory of rats trained on the radial maze has been shown to be susceptible to disruption by the protein synthesis inhibitor, anisomycin. It is not clear whether protein synthesis played a role in working memory because accurate performance on the radial maze required the storage of a large amount of information, or because the information was to be held in store for relatively long periods of time. This experiment tested these hypotheses by assessing the effect of anisomycin on choice accuracy in a comparatively simple spatial delayed alternation task. Results indicate that under the present training conditions, protein involvement in working memory is related more to the length of the retention interval than to the amount of information retained.  相似文献   
177.
This psychophysiological evaluation of an aerobic exercise program examined specifically whether aerobic training modified Pattern A for those individuals at behavioral risk for developing coronary heart disease, i.e., young Type A individuals. At pretest and posttest of this secondary prevention study, Type A and Type B subjects were assessed in three conditions: aerobic exercise program, nonaerobic activity (Aikido, a martial art) control, and notreatment control. After 10 weeks, Type A but not Type B subjects exhibited lower Pattern A behavior in the aerobic program than in control conditions. Average workout pulse rates and differentially reliable increases in aerobic capacity indicated that aerobic training was indeed aerobic, whereas aikido activity was not. Even though selected nonaerobic factors, such as locus of control and group participation, did not mediate the Pattern A decrease for Type A's when comparing aikido and aerobic conditions, changes in aerobic capacity may have been the mediator. Generalizability of the results and implications for theoretical development and clinical intervention are discussed.  相似文献   
178.
When day-old chicks are trained on a passive avoidance task there is enhanced synthesis of glycoproteins. Bilateral intracerebral injections of 20 mumole of 2-deoxygalactose (2-D-gal), administered just before and just after training on the task, produce amnesia for the avoidance. Amnesia develops slowly over the first hour and persists for at least 24 h subsequently. If 2-D-gal injections are administered 4 h prior to the training or delayed for 3 h after training, no amnesia occurs. Apart from a brief initial suppression of pecking following injection there are no effects of 2-D-gal on other observed behaviors of the birds. Within the first hour this dose of 2-D-gal inhibits [3H]fucose incorporation into acid-insoluble material by 26% (or 68%, calculated relative to free pool fucose). The amnestic effect of 2-D-gal is not shown by galactose, glucose, fucose, or 2-D-glucose. Injecting 40 mumole of galactose simultaneously with the 2-D-gal abolishes the 2-D-gal-induced amnesia; 40 mumole of fucose, however, does not abolish the amnesia. The utility of 2-D-gal as an agent for analyzing the role of glycoproteins in memory formation is discussed.  相似文献   
179.
Previous work has shown that both the perceived and actual critical (maximum) heights of surfaces that afford "sitting on " and "climbing on" can be expressed as constant proportions of each actor's leg length. The current study provides evidence that these judgments of critical action boundaries are based on an existing source of size and distance information that is already scaled with reference to the actor's eyeheight. In Experiment 1 changes in judgments of "perceived eyeheight" (an index of the intrinsic scalar) as a function of viewing distance were shown to be highly correlated with changes in the maximum height that was perceived to afford sitting on or climbing on. In Experiments 2 and 3 observers wore 10-cm blocks and made judgments about whether the heights of various surfaces afforded sitting or climbing. The use of eyeheight-scaled information as the basis for their estimates predicted the obtained pattern of errors in these judgments. With a modicum of experience wearing the blocks, however, observers were able to retune accurately their critical action boundary to a degree that would not have been predicted from their consistent overestimation of the height of the block on which they were standing. These results have implications for understanding how observers obtain information about their specific action boundary.  相似文献   
180.
Homicide which occurs in intimate social relationships was studied using data from three Western Canadian cities. Variables which may be related to the relationship and homicide are also examined. Unstable relationships are clearly differentiated from other relationships and are more likely to result in homicide. Implications for future research 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