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   78309篇
  免费   2198篇
  国内免费   30篇
  2020年   649篇
  2019年   767篇
  2018年   4252篇
  2017年   3644篇
  2016年   3190篇
  2015年   1037篇
  2014年   1021篇
  2013年   4830篇
  2012年   2322篇
  2011年   4107篇
  2010年   3530篇
  2009年   2529篇
  2008年   3245篇
  2007年   3537篇
  2006年   1421篇
  2005年   1472篇
  2004年   1285篇
  2003年   1285篇
  2002年   1204篇
  2001年   1832篇
  2000年   1810篇
  1999年   1270篇
  1998年   636篇
  1997年   548篇
  1992年   1142篇
  1991年   1093篇
  1990年   1080篇
  1989年   1024篇
  1988年   957篇
  1987年   951篇
  1986年   931篇
  1985年   1040篇
  1984年   866篇
  1983年   723篇
  1982年   545篇
  1981年   594篇
  1979年   867篇
  1978年   644篇
  1977年   589篇
  1976年   556篇
  1975年   774篇
  1974年   840篇
  1973年   913篇
  1972年   756篇
  1971年   692篇
  1970年   660篇
  1969年   697篇
  1968年   834篇
  1967年   764篇
  1966年   787篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
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   
62.
63.
64.
This study addresses the demands of alternating bimanual syncopation, a coordination mode in which the two hands move in alternation while tapping in antiphase with a metronomic tone sequence. Musically trained participants were required to engage in alternating bimanual syncopation and five other coordination modes: unimanual syncopation where taps are made (with the left or right hand) after every tone; unimanual syncopation where taps are made after every other tone; bimanual synchronization with alternating hands; unimanual synchronized tapping with every tone; and unimanual tapping with every other tone. Variability in tap timing was greatest overall for alternating bimanual syncopation, indicating that it is the most difficult. This appears to be due to instability arising from the simultaneous presence of two levels of antiphase coordination (one between the pacing sequence and the hands, the other between the two hands) rather than factors relating to movement frequency or dexterity limits of the nonpreferred hand.  相似文献   
65.
66.
67.
68.
OBJECTIVE: To examine dysregulation in biological measures associated with histories of abuse in women and whether women with premenstrual dysphoric disorder (PMDD) differ in their dysregulation. DESIGN: Twenty-five women meeting prospective criteria for PMDD and 42 non-PMDD controls underwent structured interview to determine abuse histories and lifetime Axis I diagnoses, excluding those with current Axis I disorders or using medications. MAJOR OUTCOME MEASURES: Plasma cortisol and norepinephrine (NE), heart rate (HR), blood pressure (BP), and vascular resistance index (VRI) were assessed at rest and in response to mental stress. RESULTS: A greater proportion of PMDD women had prior abuse compared with non-PMDD women. Regardless of PMDD status, all abused women had lower plasma NE and higher HRs and tended to have lower plasma cortisol at rest and during stress. Abused women also reported more severe daily emotional and physical symptoms. Greater VRI and BP at rest and during stress were seen only in PMDD women with abuse. CONCLUSION: There is persistent dysregulation in stress-responsive systems in all abused women that cannot be accounted for by current psychiatric illness or medications, and PMDD women may be differentially more vulnerable to the impact of abuse on measures reflecting alpha-adrenergic receptor function.  相似文献   
69.
70.
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