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   2363篇
  免费   303篇
  2021年   39篇
  2020年   29篇
  2019年   19篇
  2018年   22篇
  2017年   29篇
  2016年   54篇
  2015年   75篇
  2014年   64篇
  2013年   104篇
  2012年   110篇
  2011年   109篇
  2010年   83篇
  2009年   78篇
  2008年   118篇
  2007年   99篇
  2006年   104篇
  2005年   92篇
  2004年   107篇
  2003年   90篇
  2002年   87篇
  2001年   91篇
  2000年   66篇
  1999年   63篇
  1998年   34篇
  1997年   20篇
  1996年   31篇
  1995年   28篇
  1994年   19篇
  1993年   30篇
  1992年   48篇
  1991年   39篇
  1990年   50篇
  1989年   35篇
  1988年   31篇
  1987年   32篇
  1986年   29篇
  1985年   27篇
  1984年   36篇
  1983年   31篇
  1982年   27篇
  1980年   24篇
  1979年   21篇
  1978年   24篇
  1977年   19篇
  1976年   29篇
  1975年   24篇
  1974年   23篇
  1973年   20篇
  1972年   14篇
  1970年   15篇
排序方式: 共有2666条查询结果,搜索用时 15 毫秒
101.
102.
A total of 150 chief and group chief pharmacists in England took part in a survey of the structure and role of pharmacy committees in hospitals. Just over half of the hospitals had such a committee. About two-thirds of these dealt only with pharmacy matters and one-third dealt also with other matters. The number of new committees set up increased slowly until 1967 and then showed a sharp rise. Their terms of reference, membership, and manner of appointment varied greatly. Among subjects dealt with the cost of drugs and the introduction of new prescribing sheets were prominent. Many of the respondents believed that the work of the committees, often with the help of smaller, more specialized groups, had significantly improved various aspects of the local supply and use of drugs.  相似文献   
103.
104.
105.
106.
107.
Globally among biotic stresses, diseases like blight, rust and blast constitute prime constraints for reducing wheat productivity especially in Bangladesh. For sustainable productivity, the development of disease-resistant lines and high yielding varieties is vital and necessary. This study was conducted using 122 advanced breeding lines of wheat including 21 varieties developed by Bangladesh Wheat and Maize Research Institute (BAMRI) with aims to identify genotypes having high yield potential and resistance to leaf blight, leaf rust and blast diseases. These genotypes were evaluated for resistance against leaf blight and leaf rust at Dinajpur and wheat blast at Jashore under field condition. Out of 122 genotypes tested, 20 lines were selected as resistant to leaf blight based on the area under the diseases progress curve (AUDPC) under both irrigated timely sown (ITS) and irrigated late sown (ILS) conditions. Forty-two genotypes were found completely free from leaf rust infection, 59 genotypes were identified as resistant, and 13 genotypes were identified as moderately resistant to leaf rust. Eighteen genotypes were immune against wheat blast, 42 genotypes were categorized as resistant, and 26 genotypes were identified as moderately resistant to wheat blast. Molecular data revealed that the 16 genotypes showed a positive 2NS segment among the 18 immune genotypes selected against wheat blast under field conditions. The genotypes BAW 1322, BAW 1295, and BAW 1203 can be used as earlier maturing genotypes and the genotypes BAW 1372, BAW 1373, BAW 1297 and BAW 1364 can be used for lodging tolerant due to short plant height. The genotypes WMRI Gom 1, BAW 1349 and BAW 1350 can be selected for bold grain and the genotypes WMRI Gom 1, BAW 1297, BAW 1377 can be used as high yielder for optimum seeding condition but genotypes BAW 1377 and BAW 1366 can be used for late sown condition. The selected resistant genotypes against specific diseases can be used in the further breeding program to develop wheat varieties having higher disease resistance and yield potential.  相似文献   
108.
109.
The physical mechanics of music making is important both in the prevention of injuries and in guiding how music is performed and taught. Electromyography has potential as a resource in understanding the loads involved in instrumental playing; however, only a small number of projects have been undertaken, and little is understood on the muscle activity used during bowing on string instruments. This study aimed to measure the muscle activity at the bowing shoulder of a cellist during cello playing and to establish if fine-wire EMG is useful in understanding muscle recruitment in string players without interfering with normal playing ability. This project used a combination of fine-wire and surface EMG to evaluate the muscular load placed on the right shoulder of a professional cellist whilst playing a set of various bowing exercises. The results indicated that different bowing techniques produced statistically different muscle activity levels, with the supraspinatus muscle in particular maintaining higher mean contraction (20% MVC) during all bowing patterns tested. Fine-wire EMG was useful in measuring shoulder muscle load and did not interfere with normal playing technique of the subject. Overall, the study presents a working protocol from which future studies may be able conduct further research.  相似文献   
110.
The aim of the present work is to evaluate the effect of caffeine, the world’s most popular psychoactive drug, on the electric activity of the rat’s brain that exposed to extremely low-frequency magnetic field (ELF-MF), during 15 days. The obtained results showed that administration of caffeine in a group of rats by dose of 10 mg/kg (equivalent to human daily consumption) caused a reduction in the mean power amplitude of electroencephalogram (EEG) trace for almost all frequency bands especially α (8–12 Hz). It was observed that the influence of caffeine was more evident in motor cortex than in visual cortex. While the exposure of another group to ELF-MF of intensity 0.2 mT during the same period caused an enhancement in the mean power amplitude of most EEG frequency bands; this was more observed in the right hemisphere of the brain than that of the left hemisphere. The administration of caffeine while rats were exposed to ELF-MF, led, after 5 days of exposure, to a great increase in the mean power amplitude of α band at all places of recording electrodes. It may be concluded that caffeine administration was more effective in reducing the hazardous of ELF-MF in motor cortex than in visual cortex.  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