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   34536篇
  免费   1335篇
  国内免费   19篇
  2020年   352篇
  2019年   515篇
  2018年   676篇
  2017年   733篇
  2016年   704篇
  2015年   529篇
  2014年   570篇
  2013年   2765篇
  2012年   1033篇
  2011年   1137篇
  2010年   728篇
  2009年   705篇
  2008年   1005篇
  2007年   930篇
  2006年   849篇
  2005年   765篇
  2004年   700篇
  2003年   739篇
  2002年   656篇
  2001年   1247篇
  2000年   1217篇
  1999年   871篇
  1998年   393篇
  1997年   313篇
  1996年   319篇
  1995年   313篇
  1993年   312篇
  1992年   739篇
  1991年   717篇
  1990年   689篇
  1989年   626篇
  1988年   605篇
  1987年   598篇
  1986年   566篇
  1985年   626篇
  1984年   492篇
  1983年   385篇
  1979年   473篇
  1978年   352篇
  1977年   339篇
  1976年   309篇
  1975年   414篇
  1974年   424篇
  1973年   482篇
  1972年   386篇
  1971年   325篇
  1969年   331篇
  1968年   380篇
  1967年   339篇
  1966年   391篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
21.
We investigated eye‐movements during preschool children's pictorial recall of seen objects. Thirteen 3‐ to 4‐year‐old children completed a perceptual encoding and a pictorial recall task. First, they were exposed to 16 pictorial objects, which were positioned in one of four distinct areas on the computer screen. Subsequently, they had to recall these pictorial objects from memory in order to respond to specific questions about visual details. We found that children spent more time fixating the areas in which the pictorial objects were previously displayed. We conclude that as early as age 3–4 years old, children show specific eye‐movements when they recall pictorial contents of previously seen objects.  相似文献   
22.
Abstract: One claim about I , regularly made and almost universally endorsed, is that uses of the term are logically guaranteed to refer successfully (if they refer at all). The claim is only rarely formulated perspicuously or argued for. Such obscurity helps disguise the fact that those who profess to advance the claim actually turn out to support not a logical guarantee at all but merely high security through fortunate coincidence. This is not surprising. For we have no good reason to accept the claim – granted, any use of I is apt to refer successfully; but that can be explained by pragmatic features of its use. And we have some reason to reject the claim – it is notoriously difficult to see how genuine reference and guaranteed success do not exclude each other when considered as properties of the logic of any term.  相似文献   
23.
24.
Evaluated the effect of varied physician affect on subject recall, anxiety, and perceptions in a simulated tense and ambiguous medical situation. Forty women at risk for breast cancer viewed videotapes of an oncologist presenting--with either worried or nonworried affect--mammogram results. Although the mammogram results and the oncologist were the same in both presentation, analyses indicated that, compared to the women receiving the results from a nonworried physician, the women receiving the results from a worried physician recalled significantly less information, perceived the clinical situation as significantly more severe, reported significantly higher levels of state anxiety, and had significantly higher pulse rates. These results suggest that physician affect plays a critical role in patient reaction to medical information. Implications for compliance research, patient satisfaction, and physician training are discussed.  相似文献   
25.
26.
Although perceived health risk plays a prominent role in theories of health behavior, its empirical role in risk taking is less clear. In Study 1 (N = 129), 2 measures of drivers' risk-taking behavior were found to be unrelated to self-estimates of accident concern but to be related to self-ratings of driving skill and the perceived thrill of driving. In Study 2 (N = 405), out of a wide range of potential influences, accident concern had the weakest relationship with risk taking. The authors concluded that although health risk is a key feature in many theories of health behavior and a central focus for researchers and policy makers, it may not be such a prominent factor for those actually taking the risk.  相似文献   
27.
28.
OBJECTIVE: This report reviews the evidence that informs the role of health and mental health care providers in addressing youth smoking cessation. DESIGN: Qualitative literature review. RESULTS: Physicians do not consistently screen adolescents for tobacco use and fail to provide recommended cessation advice. Challenges to addressing smoking cessation include the need for procedures to ensure confidentiality and the existence of competing demands to provide other services. Few published studies have specifically addressed the effectiveness of clinical interventions. Interventions that require return visits or follow-up phone contacts are technically difficult to implement in this population. Successful interventions may require resources not available in nonresearch settings. Most studies have used brief clinical intervention as a control condition, making it impossible to evaluate its effectiveness. CONCLUSION: There is little evidence that supports current clinical smoking cessation guidelines for adolescents. More research is needed to develop inexpensive, efficient clinical interventions that can provide youths access to smoking cessation help. Future challenges include reorganizing clinical systems to offer greater counseling by support staff or in electronic formats and to provide effective booster messages and follow-up care in a population that is difficult to track.  相似文献   
29.
An electronic apparatus using infrared beams for monitoring the movements of individual bees under dark conditions is described. The searching behavior of workers in an arena was monitored over 2-h periods. Mean ambulatory velocity for one bee over a distance of 100 mm was 45.6±1.51 mm/sec (n=45). Thigmokinesis and temporal activity patterns are illustrated.  相似文献   
30.
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