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   315078篇
  免费   12279篇
  国内免费   884篇
耳鼻咽喉   4361篇
儿科学   10623篇
妇产科学   7884篇
基础医学   40585篇
口腔科学   8081篇
临床医学   27360篇
内科学   60485篇
皮肤病学   6377篇
神经病学   23257篇
特种医学   14748篇
外国民族医学   101篇
外科学   46660篇
综合类   2959篇
现状与发展   1篇
一般理论   168篇
预防医学   27123篇
眼科学   7159篇
药学   21959篇
  4篇
中国医学   311篇
肿瘤学   18035篇
  2021年   2138篇
  2019年   2061篇
  2018年   5723篇
  2017年   5564篇
  2016年   5019篇
  2015年   7115篇
  2014年   7541篇
  2013年   8527篇
  2012年   17264篇
  2011年   12714篇
  2010年   6712篇
  2009年   8202篇
  2008年   9815篇
  2007年   11070篇
  2006年   11173篇
  2005年   19395篇
  2004年   20472篇
  2003年   15936篇
  2002年   10836篇
  2001年   5473篇
  2000年   2585篇
  1999年   7030篇
  1998年   2197篇
  1992年   7605篇
  1991年   7791篇
  1990年   8002篇
  1989年   7557篇
  1988年   7033篇
  1987年   6768篇
  1986年   6488篇
  1985年   5896篇
  1984年   4416篇
  1983年   3738篇
  1982年   2161篇
  1981年   1816篇
  1980年   1785篇
  1979年   4290篇
  1978年   2935篇
  1977年   2328篇
  1976年   2008篇
  1975年   2881篇
  1974年   3470篇
  1973年   3039篇
  1972年   2974篇
  1971年   2874篇
  1970年   2696篇
  1969年   2583篇
  1968年   2322篇
  1967年   2251篇
  1966年   1982篇
排序方式: 共有10000条查询结果,搜索用时 30 毫秒
171.
A retrospective study of 232 bladder tumours with minimum follow-up 5 years is presented. The carcinoma was superficial in 66%, muscle-invasive in 31% and could not be staged in 3%. Primary treatment was mainly transurethral resection for superficial tumour, but was cystectomy or radiotherapy in 22 of 29 T1 G3. Of the superficial tumours, 71% recurred. Progression to higher T stage occurred in 15% of Ta and 29% of T1 tumours, and half of these patients died of bladder cancer. The corrected 5-year survival rates in grades 1, 2A, 2B and 3-4 were 96, 84, 64 and 43%, and in stages Ta, T1, T2 and T3 they were 94, 69, 40 and 31%. All patients with T4 tumour died within 4 years. Among the 45 patients with 40 Gy irradiation + cystectomy, the corrected 5-year survival rate was 83% in superficial and 64% in muscle-invasive tumours, and among the 38 with radical radiotherapy the rates in T1-3 were 46, 36 and 13%. Transurethral resection was successful in most Ta cases. Most T1 tumours were, like T2-4, of higher grade than Ta. Prognosis was worse in T1 than in Ta. After progression to muscle-invasive disease, even during close follow-up the outlook was poor, as poor as for patients with primary muscle-invasive disease.  相似文献   
172.
(E)-5-(2-Bromovinyl)-2'-deoxyuridine (1; BrVUdR) inhibits the replication of herpes simplex virus type 1 (HSV-1) and of varicella-zoster virus (VZV) in vitro at concentrations of 0.01 to 0.23 mumol/l, whereas herpes simplex virus type 2 (HSV-2) is influenced only at 5.5 to 27 mumol/l. In comparison to some classical and newly developed antiherpetics, i. e. 5-iodo-2'-desoxyuridine (2; idoxuridine, IDU), 9-beta-D-arabinofuranosyladenine (4; vidarabine Ara-A), 9-(2-hydroxyethoxymethyl) guanine (5; acyclovir, ACV) and 2'-fluoro-5-iodo-1-beta-D-aracytosine (6;FIAC) the following order of decreasing activity was found:1 greater than 6 greater than 5 greater than 2 greater than 4 (against HSV-1) and 6 greater than 2 greater than 5 greater than 1 greater than 4 (against HSV-2). The high selectivity of the antiviral effect of BrVUdR towards HSV-1 and TZV is based on the fact, that proliferation of different mammalian cell lines is inhibited by 50% only at concentrations as high as 90 to 170 mumol/l, resulting in a therapeutical index of 1000 to 10,000. Successful treatment of an HSV-1 encephalitis in mice as well as an HSV-1 keratitis of rabbits confirmed the efficiency of 1 in experimental animal infections. No toxic side effects in both local and systemic applications were observed. Promising data from cell culture and animal experiments recommend 1 as a potential candidate for the local and systemic treatment of HSV-1 and VZV infections in man.  相似文献   
173.
A significant increase of LDL-apolipoprotein B by 13% and LDL-cholesterol by 19% was observed in a group of 9 patients with hyperlipoproteinaemia Type III after bezafibrate treatment. Additional administration of colestipol caused a significant decrease of both LDL-apolipoprotein B by 18% and LDL-cholesterol by 25%. In 10 patients of hyperlipoproteinaemia Type IIb a significant decrease of both LDL-apolipoprotein B by 28% and LDL-apolipoprotein B by 18% was observed after bezafibrate therapy. When bezafibrate was given together with colestipol a further decrease of both LDL-cholesterol by 17% and LDL-apolipoprotein B by 16% occurred. HDL-cholesterol concentration increased significantly in both groups of hyperlipaemic patients during therapy. This may be the effect of both bezafibrate and colestipol. It is concluded that bile acid resins may effectively prevent the LDL-cholesterol concentration increase observed sometimes after clofibrate analogues.  相似文献   
174.
Summary An infant girl is described who had cor triatriatum and partial anomalous pulmonary venous connection of the left pulmonary veins to the coronary sinus, the first report of this combination of lesions. The infant also had a Dandy-Walker malformation and multiple facial and intrathoracic hemangiomas. The cardiac diagnosis was made by two-dimensional echocardiography. Cardiac catheterization and angiography confirmed the findings and also demonstrated a persistent left superior vena cava draining to the coronary sinus. The infant underwent successful surgical repair. Partial anomalous pulmonary venous connection and left superior vena cava not infrequently are associated with cor triatriatum. Although two-dimensional echocardiography is sensitive for the detection of cor triatriatum, preoperative cardiac catheterization is necessary to identify unequivocally systemic and pulmonary venous connections.  相似文献   
175.
The effect of proteases inhibitors, epsilon-amino-caproic acid and gordox, on reproduction of rotavirus SA-11 in MA-104 cells was studied by enzyme immunoassay. These inhibitors were shown to exert an inhibiting effect on rotavirus reproduction.  相似文献   
176.
BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.  相似文献   
177.
To study the hemostyptic effect of aprotinin (Trasylol) in patients undergoing extracorporeal circulation for coronary artery bypass operations, we randomized 12 of 24 patients to receive aprotinin in high dosage (about 800 mg) during extracorporeal circulation. From the resulting two groups each, one patient was excluded from the study because of postoperative myocardial infarction (control group) and surgical hemorrhage (aprotinin group) leading to a second operation. Although heparin was used for anticoagulation in all 22 patients, all had a marked increase in plasma levels of thrombin-antithrombin III complexes during extracorporeal circulation, indicating an intravasal activation of coagulation. By monitoring the plasma levels of fibrin degradation products in patients without aprotinin therapy, we recorded a concomitant hyperfibrinolysis significantly less pronounced in patients receiving aprotinin (p less than 0.005). The mean total postoperative blood loss was lower in patients receiving aprotinin (620 ml) than in control patients (1000 ml; p less than 0.03). The results confirm previous reports of a hemostyptic effect of aprotinin in cardiac operations. This effect is probably due to a prevention of hyperfibrinolysis.  相似文献   
178.
Thirty-five members of a family affected with von Hippel-Lindau's disease (VHL) were examined and lesions were found in nine of them. Four of the lesions were located in the central nervous system; two cerebellar, one spinal, one cerebral. Eye lesions were present in eight of the nine patients and complications developed in seven; six unilateral and one bilateral blindness. Both mortality and morbidity were found to be higher than in other series. This is attributed to insufficient screening of the patients with familial VHL, the late diagnosis was established only after the onset of complications. The importance of screening tests in VHL risk patients is emphasized.  相似文献   
179.
180.
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