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   234451篇
  免费   11172篇
  国内免费   399篇
耳鼻咽喉   3095篇
儿科学   7280篇
妇产科学   4771篇
基础医学   33616篇
口腔科学   5337篇
临床医学   18510篇
内科学   51770篇
皮肤病学   6226篇
神经病学   20929篇
特种医学   7079篇
外国民族医学   101篇
外科学   29081篇
综合类   992篇
一般理论   62篇
预防医学   21342篇
眼科学   4556篇
药学   16466篇
中国医学   699篇
肿瘤学   14110篇
  2023年   1249篇
  2022年   867篇
  2021年   3476篇
  2020年   2063篇
  2019年   3918篇
  2018年   7483篇
  2017年   4902篇
  2016年   4884篇
  2015年   5470篇
  2014年   5697篇
  2013年   9205篇
  2012年   16049篇
  2011年   15982篇
  2010年   7954篇
  2009年   5919篇
  2008年   13749篇
  2007年   14728篇
  2006年   13549篇
  2005年   13417篇
  2004年   12559篇
  2003年   11455篇
  2002年   10857篇
  2001年   6116篇
  2000年   6216篇
  1999年   5519篇
  1998年   890篇
  1997年   743篇
  1996年   713篇
  1992年   3220篇
  1991年   2884篇
  1990年   2753篇
  1989年   2514篇
  1988年   2386篇
  1987年   2203篇
  1986年   2095篇
  1985年   1892篇
  1984年   1408篇
  1983年   1196篇
  1982年   675篇
  1979年   1213篇
  1978年   849篇
  1977年   798篇
  1975年   803篇
  1974年   992篇
  1973年   1000篇
  1972年   942篇
  1971年   926篇
  1970年   870篇
  1969年   915篇
  1968年   795篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Seven patients with cystic fibrosis aged 6 to 20 were enrolled for 30 months in a daily exercise program. After 12 months conventional chest physiotherapy was withdrawn. Patients with low initial Shwachman scores improved as regards maximal working capacity. Spirometric data and volume of trapped gas indicated opening of closed airways. We suggest that physical exercise in general should be the basis of pulmonary therapy in cystic fibrosis. Other forms of physiotherapy are advisable when hard physical exercise is not feasible.  相似文献   
72.
This case report demonstrates how extracting a maxillary deciduous canine affects the eruption path of a labially displaced ectopically erupting permanent canine. A long-term follow-up is presented, and the biologic mechanisms are discussed.  相似文献   
73.
74.
75.
Muscle strips from the fundus, trigonum and distal ureters obtained from children at operations for vesico-ureteric reflux were studied using histochemical and immunohistochemical methods, and electrical nerve stimulation in an organ bath. A rich supply of cholinergic nerves was found and despite a partial atropine resistance the neurophysiological experiments indicated that the transmitter causing contraction of the detrusor muscle is acetylcholine. Imipramine, which is used in the treatment of enuresis, had no anticholinergic effect on the bladder in the doses used clinically. The adrenergic innervation was very sparse except around the ureter orifices. No contractile alpha-adrenoceptors could be detected but beta receptor mediated relaxation was found, which was neither of the beta 1 nor beta 2 type. A third type of beta receptor is postulated. Peptidergic nerves containing vasoactive intestinal peptide, VIP, were demonstrated in a few nerve terminals running along bundles of smooth muscle. No nerves containing enkephaline, somatostatine or substance P were found. VIP affected the detrusor muscle indicating a possible role as a modulator of transmitter action, while substance P had no effect. The anticholinergic and calcium antagonistic drug terodiline inhibited all muscle activity, whether it was induced by nerve stimulation, cholinergic drugs or a potassium rich solution, making it suitable for treatment of diurnal enuresis.  相似文献   
76.
We identified 15 patients (63 +/- 8 years) in whom CT showed no bleeding within 6 hours of stroke onset but showed ganglionic or lobar hemorrhage less than 18 hours later, without visible underlying infarct (early spontaneous intra-infarct hematoma [ESIH]). No patient had antithrombotic therapy or a coagulation disorder, but eight had hypertension. The second CT was prompted by rapid worsening (in 10) or because the first CT was not available (in five). Prior transient ischemic attacks, silent infarcts on CT, and a potential cardiac source of embolism were more common in patients with ESIH than in 200 patients with primary cerebral hemorrhage (PCH) admitted during the same period. Distal occlusions were present in four of five patients who underwent intracranial studies within the first 2 days. Most of these patients probably had embolism with early and extensive bleeding in the ischemic area. Our findings suggest that ESIH may be under-recognized, while PCH may be overdiagnosed.  相似文献   
77.
Patients with morbid obesity present a series of functional and morphologic alterations and require a careful planning for anesthetic management. We report a case of a woman weighing 260 kg who was operated on twice for the treatment of her base condition. In the first operation, general anesthesia was carried out and in the second one, epidural anesthesia was conducted. Main complications included hypoxemia and hypercapnia which persisted during the first week after operation carried out under general anesthesia.  相似文献   
78.
We studied 362 fractures of the femur that had occurred during the years 1950-57 and 1973-83, and 849 fractures of the tibia that occurred during the the years 1950-55 and 1980-83. There was an increase in age-specific incidence over aged 60 years. The risk of low-energy femoral shaft fractures also had increased in elderly women. Both fracture types shifted their age- and sex-specific incidence in the direction of a fragility pattern. There was no increase in the incidence of tibial shaft fractures. Fracture type, site, and degree of displacement of the tibial fractures remained unchanged during the 30 years, i.e, they were predominantly distal, longitudinal fractures with moderate displacement.  相似文献   
79.
In order to clarify the physiological role in vivo of H2O2-detoxifying enzymes at low and high levels of O2 tension we studied catalase (CAT), glutathione peroxidases (GP), and in vivo peroxidation (TBA-RS) in the lung and heart of Rana perezi frogs chronically treated with hyperoxia, aminotriazole (AT) -a CAT inhibitor-, or both. Hyperoxia did not change CAT, GP or TBA-RS. Aminotriazole caused an almost complete depletion of CAT, a 30% decrease of GP and a 132% (lung) to 200% (heart) increase of TBA-RS. Changes similar to these were found in the group treated with AT in hyperoxia. No mortality or changes in total or organ weight occurred in the experimental groups. Main conclusions are: (1) The maximal hyperoxia tolerance showed by frogs among vertebrates does not need antioxidant enzyme induction from lung or heart and is probably related to the presence of high constitutive levels of GP in relation to metabolic rate. (2) Even in normoxia the tissues present significant amounts of H2O2, and CAT is needed to avoid oxidative damage. GP does not compensate its absence. The implications of these results in relation to oxygen toxicity in man is discussed.  相似文献   
80.
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