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   48243篇
  免费   850篇
  国内免费   3篇
  49096篇
  2020年   548篇
  2019年   677篇
  2018年   942篇
  2017年   986篇
  2016年   1021篇
  2015年   715篇
  2014年   861篇
  2013年   3619篇
  2012年   1546篇
  2011年   1564篇
  2010年   1013篇
  2009年   932篇
  2008年   1390篇
  2007年   1376篇
  2006年   1216篇
  2005年   1077篇
  2004年   1003篇
  2003年   947篇
  2002年   982篇
  2001年   1504篇
  2000年   1429篇
  1999年   1078篇
  1998年   472篇
  1997年   447篇
  1995年   438篇
  1993年   427篇
  1992年   905篇
  1991年   838篇
  1990年   876篇
  1989年   776篇
  1988年   811篇
  1987年   752篇
  1986年   754篇
  1985年   698篇
  1984年   648篇
  1983年   585篇
  1982年   458篇
  1979年   698篇
  1978年   482篇
  1977年   431篇
  1975年   577篇
  1974年   635篇
  1973年   680篇
  1972年   534篇
  1971年   514篇
  1970年   458篇
  1969年   519篇
  1968年   624篇
  1967年   546篇
  1966年   482篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Two studies were conducted in all-electric townhouses and apartments in the winter (N = 83) and summer (N = 54) to ascertain how energy conservation strategies focusing on thermostat change and set-backs and other low-cost/no-cost approaches would affect overall electricity use and electricity used for heating and cooling, the home thermal environment, the perceived comfort of participants, and clothing that was worn. The studies assessed the effectiveness of videotape modeling programs that demonstrated these conservation strategies when used alone or combined with daily feedback on electricity use. In the winter, the results indicated that videotape modeling and/or feedback were effective relative to baseline and to a control group in reducing overall electricity use by about 15% and electricity used for heating by about 25%. Hygrothermographs, which accurately and continuously recorded temperature and humidity in the homes, indicated that participants were able to live with no reported loss in comfort and no change in attire at a mean temperature of about 62 degrees F when home and about 59 degrees F when asleep. The results were highly discrepant with prior laboratory studies indicating comfort at 75 degrees F with the insulation value of the clothing worn by participants in this study. In the summer, a combination of strategies designed to keep a home cool with minimal or no air conditioning, in conjunction with videotape modeling and/or daily feedback, resulted in overall electricity reductions of about 15% with reductions on electricity for cooling of about 34%, but with feedback, and feedback and modeling more effective than modeling alone. Despite these electricity savings, hygrothermograph recordings indicated minimal temperature change in the homes, with no change in perceived comfort or clothing worn. The results are discussed in terms of discrepancies with laboratory studies, optimal combinations of video-media and personal contact to promote behavior change, and energy policies that may be mislabeled as sacrificial and underestimate the effectiveness of conservation strategies such as those investigated in these studies.  相似文献   
994.
Mental arithmetic abilities were studied among unschooled African adults and American college students. A set of problems tested the use of the four basic arithmetic operations. Performance was analyzed for: strategies, implicit arithmetic principles, and explicit explanations of the principles. Both groups showed accurate mental arithmetic strategies related to the base ten structure of their native counting systems. The American students' mental strategies additionally made use of algorithms based on written place values. Several principles were implicit in the calculation strategies of both groups, and both used these principles to short-cut calculations. Though the African subjects did not, the American subjects did describe these abstract principles in explicit common language or algebraic expressions. Relationships between schooling and cognition are discussed.  相似文献   
995.
The time course of memory decay for infant rats may shed light on the processes responsible for infantile amnesia. A taste aversion conditioning procedure appropriate for both neonatal and adult rats was employed in four experiments to investigate the ontogeny of extended retention. In Experiment 1, rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those rats conditioned when 20 or 60 days old demonstrated significant taste aversions. Experiments 2 and 3 established that rats 14-15 days old and older were able to retain significant taste aversions following a 25-day retention interval. Younger rats did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Experiment 4). These findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident.  相似文献   
996.
The functional relation between restricted damage to ventral primary somatosensory neocortex and the ability of rats to acquire conditioned taste aversion (CTA( was examined by a combination of behavioral and neurohistological techniques. Lesions confined exclusively to the established gustatory neocortex (GN) did not disrupt CTA acquisition, nor did lesions confined to suprarhinal cortical areas ventral to the GN. Lesions that encroached on dorsal prepiriform and insular cortices produced CTA acquisition deficits and damaged a large proportion of efferent projections to the prefrontal and precentral neocortex. In a second experiment, lesions of dorsal prepiriform and insular cortices did not modify taste preference-aversion threshold to any of the four taste modalities. It is concluded tha ventral somatosensory neocortical fields, including the established GN, do not mediate CTA acquisition and that rhinal cortices ventral and posterior to the GN are preferentially involved in associative learning for tastes and illness.  相似文献   
997.
This study examines religious faith as associated with adjustment to end-stage renal failure and its treatment regimen of maintenance hemodialysis. Both quantitative and qualitative data were collected initially and after a three-year interval in order to observe changes over time. The variable of the patient's perception of the import of religious faith was found to be positively related to interactional behavior and sick role behavior and to be inversely associated with alienation. Content analysis of qualitative responses for the item of perceived import of religious faith revealed a pattern of increasingly more positive patient attitudes occurring over time.  相似文献   
998.
In order to understand what it means to be a physician, we must, according to Dr. Edmund Pellegrino, analyze four words that capture the essence of the medical enterprise: profession, patient, compassion, and consent. The resultant model provides a rational and secular basis upon which the Jewish or Christian physician can then build an understanding of medicine in its peculiarly religious form. This religious form is likewise characterized by four words: vocation, neighbor, love, and covenant. An analysis of these words provides a model of and for the religious physician.  相似文献   
999.
A limited national sample of 49 school psychologists and 30 regular education teachers provided information on assessment for the purpose of instructional planning. School psychologists listed the types of information they most often collected for this purpose and teachers listed the types of information considered most useful for this purpose. While some indications of agreement were found between school psychologists and teachers, there were also several inconsistencies in the views of the two groups regarding assessment procedures for instructional planning. The findings are discussed in light of empirical evidence on the contribution of various types of assessment data to instructional planning.  相似文献   
1000.
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