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   968559篇
  免费   99894篇
  国内免费   2345篇
耳鼻咽喉   13844篇
儿科学   32671篇
妇产科学   26663篇
基础医学   140471篇
口腔科学   29259篇
临床医学   85957篇
内科学   203674篇
皮肤病学   25566篇
神经病学   83331篇
特种医学   38404篇
外国民族医学   336篇
外科学   154457篇
综合类   19063篇
一般理论   268篇
预防医学   68400篇
眼科学   21320篇
药学   68793篇
中国医学   2787篇
肿瘤学   55534篇
  2020年   8457篇
  2019年   16490篇
  2018年   18163篇
  2017年   17467篇
  2016年   18678篇
  2015年   19551篇
  2014年   23140篇
  2013年   30346篇
  2012年   29273篇
  2011年   30792篇
  2010年   24604篇
  2009年   20592篇
  2008年   27889篇
  2007年   28445篇
  2006年   28664篇
  2005年   27966篇
  2004年   26828篇
  2003年   26007篇
  2002年   25675篇
  2001年   42038篇
  2000年   43170篇
  1999年   36493篇
  1998年   9985篇
  1997年   9156篇
  1996年   9095篇
  1995年   8453篇
  1994年   8091篇
  1992年   28208篇
  1991年   26986篇
  1990年   26413篇
  1989年   25351篇
  1988年   23555篇
  1987年   23173篇
  1986年   22252篇
  1985年   21154篇
  1984年   15807篇
  1983年   13477篇
  1982年   8088篇
  1979年   14590篇
  1978年   10209篇
  1977年   8627篇
  1976年   8148篇
  1975年   8959篇
  1974年   10697篇
  1973年   10182篇
  1972年   9661篇
  1971年   8919篇
  1970年   8585篇
  1969年   8027篇
  1968年   7684篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Our study was intended to determine whether power Doppler sonography can be considered superior to color Doppler technique in depiction of normal orbital vasculature. Ten healthy volunteers (20 eyes) were examined with a 10 MHz linear probe; each orbital vessel was recorded with both color and power Doppler methods; the images were reviewed independently by all the observers, who agreed that power Doppler clearly is superior to color Doppler technique for evaluation of the anatomy of orbital arteries and veins.  相似文献   
132.
133.
Cultured keratinocytes were used as allografts on burn wounds in two patients. In both patients successful covering of the wounds was obtained. DNA fingerprinting of the epidermis covering the wounds 21 days later showed that the cultured keratinocytes were replaced by the patients' cells.  相似文献   
134.
Free-floating clots of the extracranial internal carotid artery are generally considered as surgical emergencies. This retrospective study analyzes six free-floating clots diagnosed by arteriography. Three of these patients had a fixed stroke while the other three had an evolving stroke. Three patients had antecedent ocular or hemispheric transient ischemic attacks. The causes of free-floating clots in the internal carotid artery were atheromatous stenosis in two cases, ulcerated plaque in three cases, and carotid artery dissection in one. All six patients were seen late, approximately 15 hours after their neurologic accident. They were treated with intravenous heparin over a two to five week period. Repeat arteriograms demonstrated complete clot lysis in four instances, while partial lysis was seen in one case. Moderate extension of thrombus occurred in one case only. No further neurologic complications were noted during the treatment by heparin. As indicated by follow-up arteriographic findings, secondary surgery was performed for major carotid lesions and residual clots in five cases. The free-floating thrombus syndrome of the carotid artery should not be considered as a surgical emergency when discovered late in the wake of an acute neurologic accident.  相似文献   
135.
136.
Professional exposure to vegetable dusts affect the respiratory function of the exposed subjects. A previous survey conducted in an industrial flour-mill demonstrated a higher frequency of respiratory symptoms in workers compared to a control group. Ten subjects employed in a work site particularly exposed to dust were studied. Each subject answered a questionnaire and performed on Mondays and Fridays, at the begenning and end of his work shift, a flow volume curve and an isocapnic hyperventilation test. The aerobiology of the professional environment was also measured. We noted: 1) in the flow volume curves: a drop in the FEV1 during the Monday morning shift, a significant difference between the FEV1 (p<0.05) and the MMEFR 25–75 (p<0.05) measured at 6 am on Monday and Friday, and between the MMEFR 25–75 values obtained at 12 noon on Monday and Friday (p<0.05). 2) after isocapnic hyperventilation, a significant drop in the MMEFR 25–75 at 6 am on Monday (p<0.01) and in the FEV1 and MMEFR 25–75 at 12 noon on Mondays (p<0.05), a significant drop in the FEV1 at 1 pm on Monday (p<0.01).  相似文献   
137.
Acetaldehyde, the first metabolite of ethanol, reacts with haemoglobinin vitro to produce acetaldehyde—haemoglobin adducts.Some clinical studies on the minor haemoglobins have suggestedthat these adducts may be formed in people abusing alcohol.Under hydrolysis of haemoglobin, with oxalic acid at 100°Cin sealed vials, some acetaldehyde was released and then specificallydetermined by HPLC. The kinetics of hydrolysis were studiedusing haemoglobin previously labelled with 14[C] acetaldehyde.The maximum liberation of 14[C] acetaldehyde was obtained after3 hr 30 min hydrolysis and this time factor was then utilizedin the analysis of alcoholic and control haemoglobin. Thus,we have confirmed the formation of acetaldehyde haemoglobinadducts in vivo. It must be noted that the released acetaldehydecorresponds only to an index of the stable adducts. The levelswere higher in alcoholics than in controls (1.417±0.171and 1.295±0.139 nmol/mg Hb, respectively, P<0.001).In conclusion, this marker is not a convenient tool for themonitoring of alcohol exposure levels because of the low differencesbetween alcoholic and control haemoglobins.  相似文献   
138.
Since its introduction in early 1985, the Volk +90D lens has become a very popular auxiliary lens for biomicroscopic fundus evaluation. The Volk +90D lens provides a wide field of view which is accessible by simple scanning of the biomicroscope. The necessity to hand hold the lens, however, has not always provided enough stability, particularly for the novice user. This article describes a newly introduced holder for the Volk +90D lens which mounts on the base of the biomicroscope headrest providing rapid and stable lens placement. Use of this holder improves the technique of retinal examination and photography by stabilizing the image and by freeing both hands to operate the slit lamp biomicroscope. The enhanced stability afforded by this holder also gives the examiner the practical capability of viewing the posterior pole without mydriasis.  相似文献   
139.
Tear mucus crystallization in children with cystic fibrosis   总被引:1,自引:0,他引:1  
Cystic fibrosis is characterized by an abnormally high electrolyte concentration in exocrine secretions. The authors performed the tear mucus ferning test in 26 eyes of children with cystic fibrosis and compared the results to those in an equal number of age-matched normals. The results suggest that the increased electrolyte concentration could be responsible for the increased hyperviscosity of mucus. The tear mucus ferning test appears to be a suitable diagnostic test for the assessment of cystic fibrosis.  相似文献   
140.
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