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   46775篇
  免费   1751篇
  国内免费   17篇
  48543篇
  2020年   505篇
  2019年   588篇
  2018年   840篇
  2017年   772篇
  2016年   905篇
  2015年   618篇
  2014年   795篇
  2013年   4548篇
  2012年   1360篇
  2011年   1380篇
  2010年   937篇
  2009年   938篇
  2008年   1374篇
  2007年   1255篇
  2006年   1161篇
  2005年   986篇
  2004年   996篇
  2003年   998篇
  2002年   947篇
  2001年   1330篇
  2000年   1309篇
  1999年   1021篇
  1998年   547篇
  1997年   483篇
  1996年   583篇
  1995年   594篇
  1994年   572篇
  1993年   542篇
  1992年   995篇
  1991年   892篇
  1990年   894篇
  1989年   791篇
  1988年   803篇
  1987年   780篇
  1986年   766篇
  1985年   762篇
  1984年   705篇
  1983年   581篇
  1982年   482篇
  1981年   510篇
  1980年   470篇
  1979年   661篇
  1978年   520篇
  1976年   470篇
  1975年   580篇
  1974年   587篇
  1973年   634篇
  1972年   590篇
  1971年   530篇
  1968年   546篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
153.
Context and structure in conceptual combination   总被引:8,自引:0,他引:8  
  相似文献   
154.
Two modes of learning for interactive tasks   总被引:5,自引:0,他引:5  
N A Hayes  D E Broadbent 《Cognition》1988,28(3):249-276
  相似文献   
155.
The care of the patient with cancer requires the development not only of a medical plan, but an ethical plan as well. This plan should integrate the physician's and the patient's perceptions of medical and ethical propriety. Jewish biomedical ethical principles are based on the teaching of the Old Testament and its various interpretations. In this paper, I discuss how these principles can be used to help guide the physician caring for the patient with cancer. Other ethical systems could be applied in a similar fashion.  相似文献   
156.
Hindsight bias: An interaction of automatic and motivational factors?   总被引:1,自引:0,他引:1  
If subjects are asked to recollect a former response after having been informed about the correct response, their recollection tends to approach the correct response. This effect has been termedhindsight bias. We studied hindsight bias in an experiment requiring numerical responses to almanac-type questions for physical quantities. We varied (1) the time at which the correct information was provided, (2) the encoding of the original responses by asking/not asking subjects to give a reason for the respective response, and (3) the motivation to recall correctly. We found that hindsight is less biased if reasons are given and if the correct information is provided at an earlier time. Motivation had only interactive effects: (1) With high motivation to recall correctly, the time the correct information was provided had no influence. (2) With reasons given, the variation of motivation showed no effect. These results rule out purely motivational and purely automatic explanations.  相似文献   
157.
158.
The precaution adoption process   总被引:47,自引:0,他引:47  
This article presents a critique of current models of preventive behavior. It discusses a variety of factors that are usually overlooked-including the appearance of costs and benefits over time, the role of cues to action, the problem of competing life demands, and the ways that actual decision behavior differs from the rational ideal implicit in expectancy-value and utility theories. Such considerations suggest that the adoption of new precautions should be viewed as a dynamic process with many determinants. The framework of a model that is able to accommodate these additional factors is described. This alternative model portrays the precaution adoption process as an orderly sequence of qualitatively different cognitive stages. Data illustrating a few of the suggestions made in the article are presented, and implications for prevention programs are discussed.  相似文献   
159.
The finding that there are maturational differences between the ability to learn and to perform a task requiring young Wistar rats to inhibit a response was examined. Using an operant task, different from that employed in the previous studies, it was established that the finding was not task specific. The relative contribution of different periods in the early training stage to later savings in learning was also examined. It was confirmed that there is an early performance deficit by weanling rats on tasks requiring them to inhibit a previously learned response in the presence of a discriminative cue. Rats given early training on the task during this period of performance deficit nevertheless showed significant savings in later learning of the task, indicating that they had learned as much in that stage as they would have if given the same training at an age when performance is at the adult level. It was revealed that despite age-related differences in performance it was not so much the age at which early training took place as the amount of training given that affected later savings. The results are discussed in light of evidence of similar differences between the learning and performance of discrimination tasks exhibited by young children.  相似文献   
160.
The modulation of attacks, genital sniffs, and mounts in male SJL/J mice by ovarian-dependent urogenital substances in the urine voided by estrous females was examined. Urogenital substances were applied onto the external urogenital areas of ovariectomized mice. When compared with urine voided by estrous females, which stimulated genital sniffing, mounting, and reduced aggression, bladder urine was ineffective. Genital sniffing and mounting was stimulated by estradiol-17 beta, vaginal fluids, and preputial extract. Aggression was reduced by estradiol-17 beta, urethral catheterized urine, and vaginal fluids. Preputialectomy reduced, but did not eliminate, urinary stimulation of genital sniffing and mounting. Preputial extract stimulated aggression. Urogenital substances from ovariectomized females were ineffective in reducing attacks and stimulating genital sniffs and mounts. It was concluded that the ovarian-dependent chemosignals in the urine voided by estrous females are contributed by the urethra, vagina, and preputial gland, perhaps in part through the excretion of unconjugated estrogens.  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