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   39170篇
  免费   1597篇
  国内免费   14篇
  2020年   365篇
  2019年   431篇
  2018年   583篇
  2017年   590篇
  2016年   662篇
  2015年   492篇
  2014年   567篇
  2013年   2640篇
  2012年   1104篇
  2011年   1072篇
  2010年   672篇
  2009年   645篇
  2008年   961篇
  2007年   948篇
  2006年   816篇
  2005年   794篇
  2004年   750篇
  2003年   679篇
  2002年   700篇
  2001年   1281篇
  2000年   1224篇
  1999年   894篇
  1998年   397篇
  1992年   865篇
  1991年   810篇
  1990年   825篇
  1989年   723篇
  1988年   716篇
  1987年   692篇
  1986年   718篇
  1985年   797篇
  1984年   592篇
  1983年   549篇
  1982年   372篇
  1981年   361篇
  1980年   346篇
  1979年   690篇
  1978年   432篇
  1977年   419篇
  1976年   414篇
  1975年   589篇
  1974年   669篇
  1973年   718篇
  1972年   621篇
  1971年   586篇
  1970年   574篇
  1969年   563篇
  1968年   755篇
  1967年   666篇
  1966年   597篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
The purpose of this investigation was to evaluate carefully smoking-related knowledge and beliefs and their relationships to smoking status in a large, heterogeneous sample of smokers and nonsmokers in two settings: (a) a large, biracial southern city and (b) a small midwestern community. Participants were 611 (198 male, 413 female) adult respondents to a random-dialing telephone survey in Fargo, North Dakota (n = 200), and Memphis, Tennessee (n = 411). Each participant was given the Smoking Attitudes Survey, which assesses generalized health beliefs as well as health-related problems associated with smoking. Participants' knowledge of smoking-associated diseases (e.g., lung cancer) and of diseases not associated with smoking (e.g., kidney stones) was assessed. Stepwise regression analysis of composite knowledge scores revealed four independent predictors of the health consequences of smoking: education, race, smoking status, and income. Smokers, compared to nonsmokers, reported less knowledge related to the health consequences of smoking, were more likely to be male, were less concerned with the health consequences of smoking, and were more concerned about the health consequences of cholesterol. The best predictor of smokers who had never attempted cessation was their greater concern over weight control when compared to smokers with a history of smoking cessation attempts. The results are discussed in terms of smoking prevention and intervention efforts.  相似文献   
182.
The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described.  相似文献   
183.
Analogical transfer, problem similarity, and expertise   总被引:6,自引:0,他引:6  
When we encounter a new problem, we are often reminded of similar problems solved earlier and may use the solution procedure from an old problem to solve a new one. Such analogical transfer, however, has been difficult to demonstrate empirically, even within a single experimental session. This article proposes a framework for conceptualizing analogical problem solving that can account for the conflicting findings in the literature. In addition, the framework leads to two predictions concerning the transfer behavior of experts and novices. These predictions concern both positive and negative transfer and are based on the different types of features included in the problem representations of experts and novices. First, when two problems share structural features but not surface features, spontaneous positive transfer should be more likely in experts than in novices. Second, when two problems share surface but not structural features, spontaneous negative transfer should be stronger for novices than for experts. These predictions were supported by the results of three experiments involving college students solving a complex arithmetic word problem.  相似文献   
184.
Contextually relevant aspects of meaning   总被引:2,自引:0,他引:2  
A series of six experiments investigated whether inferences about contextually relevant aspects of meaning were encoded into memory during reading. In all the experiments, subjects studied short paragraphs. Then, test sentences were presented that expressed relevant aspects of meaning that had not been explicitly stated in the paragraphs. For example, for a paragraph about searching for the correct color to paint a picture of a tomato, a relevant aspect of meaning would be that tomatoes are red. The test sentences were presented either immediately following the relevant paragraph or after a delay. With immediate testing, it was argued that the facilitation obtained in verification latency could result from processes occurring either when the context was read or when the test sentence was verified. With delayed testing, evidence was found to support the hypothesis that contextually relevant aspects of meaning are incorporated into the memory representation of the paragraph, but such evidence was obtained only when the retrieval environment encouraged the use of newly learned information in the decision process on the test sentence.  相似文献   
185.
Group work as an integral part of counsellor training appears to have been under-utilised. Certainly it is the case that empirical evaluations of such group work appear rarely in guidance and counselling journals. An attempt is made to remedy these deficiencies by reviewing studies relevant to counsellor training and to report on 17 years of research and experience with group work within a counsellor training programme at a New Zealand university.  相似文献   
186.
The vocationally-indecisive individual presents a major counselling problem. The theory and research behind career indecision is discussed and a counselling approach based on identity formation is outlined. Four identity statuses — Identity Achievements, Foreclosures, Identity Diffusions, and Moratoriums — are described and counselling approaches for each are explored.  相似文献   
187.
We explored what kind of information is acquired when amnesic patients are able to exhibit significant retention on tests of cued recall and recognition memory. Amnesic patients and control subjects attempted to learn sets of sentences. Memory for the last word in each sentence was tested after 1 hr in the case of the amnesic patients, or after 1 to 2 weeks in the case of (delayed) control subjects. Amnesic patients and (delayed) control subjects performed at similar levels on tests of cued recall and recognition memory. Amnesic patients were just as confident of their correct answers as were control subjects. However, amnesic patients were no more disadvantaged than control subjects when they were cued indirectly by presenting paraphrases of the original sentences. These findings demonstrate that the residual knowledge retained by amnesic patients can be as flexible, as accessible to indirect cues, and as available to awareness as the knowledge retained by (delayed) control subjects.  相似文献   
188.
A cost-benefit analysis of demand for food.   总被引:20,自引:17,他引:3       下载免费PDF全文
Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio.  相似文献   
189.
Rats were allowed to forage in a simulated natural environment made up of eight food sources (patches) each containing a fixed number of pellets. Two of the eight contained an extra supply of peanuts. The peanut patches were signaled by an olfactory/visual cue located at the bottom of the ladder leading to the patch. In successive phases the number of sessions per day, height of the patches, and availability of peanuts were manipulated. Subjects showed evidence of discrimination learning under these conditions, although the degree of discriminatory behavior varied as a function of environmental manipulations. Assessment of behavior within foraging sessions showed that subjects systematically changed their patterns of utilization of patches across time. Sampling or exploration, as well as food reinforcement, seem implicated in these results.  相似文献   
190.
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