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   1008713篇
  免费   67043篇
  国内免费   2599篇
耳鼻咽喉   14162篇
儿科学   32051篇
妇产科学   28584篇
基础医学   141434篇
口腔科学   28625篇
临床医学   81607篇
内科学   209410篇
皮肤病学   22567篇
神经病学   79954篇
特种医学   38841篇
外国民族医学   339篇
外科学   155083篇
综合类   19625篇
一般理论   281篇
预防医学   75605篇
眼科学   22618篇
药学   71416篇
中国医学   2328篇
肿瘤学   53825篇
  2021年   8171篇
  2019年   9001篇
  2018年   13555篇
  2017年   9767篇
  2016年   10091篇
  2015年   11381篇
  2014年   15358篇
  2013年   23781篇
  2012年   33832篇
  2011年   35954篇
  2010年   20915篇
  2009年   18804篇
  2008年   32980篇
  2007年   35123篇
  2006年   34658篇
  2005年   34071篇
  2004年   32140篇
  2003年   30890篇
  2002年   30211篇
  2001年   44075篇
  2000年   45683篇
  1999年   38569篇
  1998年   10362篇
  1997年   9397篇
  1996年   9318篇
  1995年   8622篇
  1994年   8220篇
  1992年   29124篇
  1991年   27754篇
  1990年   27122篇
  1989年   25929篇
  1988年   24052篇
  1987年   23639篇
  1986年   22737篇
  1985年   21556篇
  1984年   16109篇
  1983年   13718篇
  1982年   8205篇
  1979年   14863篇
  1978年   10380篇
  1977年   8782篇
  1976年   8319篇
  1975年   9179篇
  1974年   10961篇
  1973年   10484篇
  1972年   9901篇
  1971年   9182篇
  1970年   8830篇
  1969年   8284篇
  1968年   7918篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
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   
132.
The present authors investigated the excretion, distribution and pharmacokinetics of the novel potential antirheumatic agent flobufen and its active metabolite after p.o. and i.v. doses of 2, 10 and 50 mg/kg administered to rats. The drug is resorbed well from the digestive tract and mostly it is metabolized to the principal metabolite M, which is only slowly excreted from the organism mainly by renal clearance. Within the whole dose range the kinetics of the drug is linear. Binding of flobufen and M to proteins is high (95-99%). The highest concentrations of radioactive metabolites (mostly M) were found in the plasma, liver, lungs, kidneys, connective tissue and inflammatory foci. The penetration of metabolites through the placenta and excretion in human milk are relatively important.  相似文献   
133.
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   
134.
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