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   196477篇
  免费   4161篇
  国内免费   439篇
耳鼻咽喉   2761篇
儿科学   7503篇
妇产科学   5895篇
基础医学   25441篇
口腔科学   5851篇
临床医学   15409篇
内科学   35427篇
皮肤病学   4553篇
神经病学   12044篇
特种医学   10678篇
外国民族医学   97篇
外科学   29374篇
综合类   1098篇
一般理论   2篇
预防医学   16376篇
眼科学   4282篇
药学   13580篇
  2篇
中国医学   134篇
肿瘤学   10570篇
  2018年   3518篇
  2017年   3878篇
  2016年   3186篇
  2015年   4855篇
  2014年   4265篇
  2013年   3411篇
  2012年   9789篇
  2011年   4689篇
  2010年   2178篇
  2009年   3854篇
  2008年   2054篇
  2007年   2789篇
  2006年   3037篇
  2005年   11198篇
  2004年   12683篇
  2003年   8273篇
  2002年   3489篇
  2001年   4440篇
  2000年   1796篇
  1999年   5941篇
  1998年   571篇
  1996年   425篇
  1992年   6932篇
  1991年   7174篇
  1990年   7424篇
  1989年   7007篇
  1988年   6537篇
  1987年   6316篇
  1986年   6024篇
  1985年   5314篇
  1984年   3650篇
  1983年   2966篇
  1982年   1050篇
  1981年   801篇
  1980年   867篇
  1979年   3877篇
  1978年   2416篇
  1977年   1824篇
  1976年   1598篇
  1975年   2516篇
  1974年   3155篇
  1973年   2774篇
  1972年   2796篇
  1971年   2787篇
  1970年   2574篇
  1969年   2485篇
  1968年   2254篇
  1967年   2181篇
  1966年   1906篇
  1965年   1140篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
101.
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   
102.
(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   
103.
This content was analysed in patients with chronic periodontitis and in control subjects. In periodontal disease, it was characterized by higher mean concentrations of glycine, proline, tyrosine and delta-aminovaleric acid than in controls (p less than 0.001). However, the range of values varied considerably in the two groups. There were differences between periodontitis and control samples in the proportions of proline to serine (p less than 0.01) and proline to glutamic acid and glutamine (p less than 0.05). Bacterial contamination and decomposition of salivary proteins is responsible for the elevated salivary levels of glycine, proline, tyrosine and delta-aminovaleric acid in the periodontal group.  相似文献   
104.
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   
105.
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   
106.
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   
107.
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   
108.
109.
110.
Reported in this paper are postoperative results recorded from 120 patients, 3 years after selective proximal vagotomy for uncomplicated duodenal ulcer. There was no intraoperative lethality and no recurrence in 96.7 per cent of all cases, while Visick grades I on II were recorded from 98.2 per cent. Radiologically and gastroscopically detected pathological processes receded soon. Average postoperative reduction in acid secretion was 66.2 per cent in BAO and 46.8 per cent in MAO. Acid values re-increased thereafter, and three years later reduction rates still amounted to 43.7 per cent in BAO and 28.6 per cent in MAO. Indications for proximal gastric vagotomy are discussed in some detail.  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