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   2349695篇
  免费   172017篇
  国内免费   5814篇
耳鼻咽喉   32219篇
儿科学   77720篇
妇产科学   66952篇
基础医学   344369篇
口腔科学   65515篇
临床医学   216217篇
内科学   453091篇
皮肤病学   47962篇
神经病学   189931篇
特种医学   88005篇
外国民族医学   699篇
外科学   343128篇
综合类   51117篇
现状与发展   2篇
一般理论   730篇
预防医学   188865篇
眼科学   53284篇
药学   176257篇
  7篇
中国医学   5047篇
肿瘤学   126409篇
  2018年   25307篇
  2017年   19054篇
  2016年   21040篇
  2015年   24126篇
  2014年   33312篇
  2013年   51380篇
  2012年   70464篇
  2011年   75200篇
  2010年   44088篇
  2009年   40971篇
  2008年   70463篇
  2007年   75254篇
  2006年   76009篇
  2005年   73979篇
  2004年   70792篇
  2003年   67928篇
  2002年   66369篇
  2001年   103975篇
  2000年   106663篇
  1999年   90213篇
  1998年   26023篇
  1997年   23490篇
  1996年   23414篇
  1995年   22147篇
  1994年   20869篇
  1993年   19465篇
  1992年   72490篇
  1991年   71426篇
  1990年   69773篇
  1989年   67122篇
  1988年   62331篇
  1987年   60893篇
  1986年   58209篇
  1985年   55694篇
  1984年   41842篇
  1983年   35978篇
  1982年   21707篇
  1981年   19251篇
  1979年   39081篇
  1978年   27691篇
  1977年   23350篇
  1976年   22488篇
  1975年   23881篇
  1974年   28597篇
  1973年   27878篇
  1972年   26190篇
  1971年   24274篇
  1970年   22635篇
  1969年   21300篇
  1968年   20118篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Four cases of cervical vertebral artery (VA) dissection are reported. In three patients VA dissection was associated with neck trauma. All patients were young or middle-aged (range 27 to 49 years). In two there was a history of migraine. Pain preceded neurological symptoms from hours to six weeks. Three patients had neurological deficits including elements of the lateral medullary syndrome, and one experienced recurrent transient ischaemic attacks in the vertebrobasilar territory. Angiographic findings included irregular stenosis, occlusion and pseudoaneurysm; in two patients VA abnormalities were bilateral. All patients were treated with anticoagulants and improved. In a review of 28 cases with traumatic dissection and 29 cases with spontaneous dissection of the VA reported in the literature, distinct clinical and angiographic features emerge. Aetiology remains obscure in most cases of spontaneous dissection and management is still controversial.  相似文献   
992.
Bipolar disorder is a serious mental illness affecting a large number of Americans. While lithium, the treatment of choice for this disorder, is usually effective, a substantial number of individuals with bipolar disorder are not helped by lithium or are intolerant to its side effects. Consequently, investigators are searching for alternative drugs in order to treat lithium-resistant patients. Although a number of alternative drug treatments have been discussed in the literature, only the anticonvulsants carbamazepine and valproate appear to warrant serious consideration at this time. Future research will further define their roles as antimanic agents.  相似文献   
993.
This study was performed to gain a better understanding of EEG frequency analysis test-retest reliability in normal healthy adults, and to evaluate factors which could influence the measured inter-record differences. Nineteen subjects underwent serial EEG recordings at 5 min and 12-16 week intervals. Records were visually edited using a standardized protocol, and FFT frequency analysis performed on segments of 60, 40, or 20 sec total length. Correlation coefficients for broad band features averaged 0.92 over the 5 min retest interval and 0.84 over the 12-16 week interval. There was essentially no difference between correlation coefficients of absolute and relative power features. Coefficients based on 60 sec records were marginally higher than those of 40 or 20 sec records. On the other hand, test-retest percent differences were typically lower for relative as opposed to absolute power features, and 60 sec records showed consistently lower percent differences than did 40 or particularly 20 sec records. Peak alpha frequency and mean frequency were the most stable EEG features at either interval. Montage had significant effects on test-retest differences at the 12-16 week interval. A significant association between intra-record and inter-record variability could not be demonstrated.  相似文献   
994.
995.
996.
In the processing of the waste products of phosphorus containing fertilizer production, several major health-related factors were identified depending on the industrial site's peculiarities: unfavourable microclimate conditions (both cold and heat), relative temperature differences, noise and vibration caused by the equipment, semi-product's, additives' and finished product's dusts, fluorine- and phosphorus-containing substances' affects and poor illumination. The proposed data were used for health-related improvements in the occupational conditions.  相似文献   
997.
NTS fallout-induced multiple myeloma in Utah.   总被引:1,自引:0,他引:1  
  相似文献   
998.
999.
1000.
The contributors propose a selective photometric technique for detection of sodium and potassium cyanides in different washings, sewage, overalls extraction. The technique was based on the formation of a polymetyne dye, and barbituric acid and pyridine reactions. It proved efficient in detecting the cyanides within 0.01-0.054 mg/dm3, 1-100 mg/l, 0.08-1.24 mg/dm3 with deviations not exceeding 23%. Duration of the test was limited to 25-30 min.  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