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   939348篇
  免费   66876篇
  国内免费   1374篇
耳鼻咽喉   13087篇
儿科学   24651篇
妇产科学   23412篇
基础医学   134004篇
口腔科学   28361篇
临床医学   81225篇
内科学   184613篇
皮肤病学   19310篇
神经病学   73001篇
特种医学   37003篇
外国民族医学   79篇
外科学   153127篇
综合类   18139篇
现状与发展   1篇
一般理论   249篇
预防医学   62304篇
眼科学   21479篇
药学   73068篇
  3篇
中国医学   2176篇
肿瘤学   58306篇
  2018年   9222篇
  2017年   7235篇
  2016年   7995篇
  2015年   9085篇
  2014年   12290篇
  2013年   17908篇
  2012年   24665篇
  2011年   25540篇
  2010年   15143篇
  2009年   14510篇
  2008年   24961篇
  2007年   26101篇
  2006年   26826篇
  2005年   25754篇
  2004年   24890篇
  2003年   23918篇
  2002年   23467篇
  2001年   54853篇
  2000年   56642篇
  1999年   47068篇
  1998年   10788篇
  1997年   9518篇
  1996年   9636篇
  1995年   8963篇
  1994年   8307篇
  1993年   7620篇
  1992年   35547篇
  1991年   33967篇
  1990年   32771篇
  1989年   31931篇
  1988年   29041篇
  1987年   28300篇
  1986年   26333篇
  1985年   25193篇
  1984年   17867篇
  1983年   15169篇
  1982年   7828篇
  1981年   6796篇
  1979年   15827篇
  1978年   10621篇
  1977年   9075篇
  1976年   7892篇
  1975年   8647篇
  1974年   10484篇
  1973年   9878篇
  1972年   9380篇
  1971年   8868篇
  1970年   8442篇
  1969年   7937篇
  1968年   7209篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
To investigate the role of cell-mediated immunity (CMI) in glomerulonephritis (GN), we identified the infiltrating immune cells both within the glomerulus and in the interstitium. Frozen sections from 103 patients with various forms of GN: 10 with minor glomerular abnormality (MGA) as control, 10 with minimal change nephrotic syndrome (MCNS), 10 with membranous nephropathy (MN), 9 with focal glomerulosclerosis (FGS), 30 with IgA nephropathy (IgAN), 22 with acute post streptococcal glomerulonephritis (APSGN), and 2 with rapidly progressive glomerulonephritis (RPGN) were examined using monoclonal antibodies (MoAb) by indirect immunoalkaline-phosphatase labelling. In most glomerulonephritis, monocyte/M phi and helper/inducer T cells were predominantly infiltrating in the interstitium, but intraglomerular infiltration was rare, except for APSGN. This interstitial infiltration increased proportionally to the level of serum creatinine, and was most prominent in RPGN. Apparently different distribution was seen in APSGN, that is, prominent increase in total number of intra-glomerular monocyte/M phi infiltration with slightly increased T cells. The change was correlated with time after onset; namely the more leucocytic infiltration was observed when the tissue was taken earlier. These data suggest that in APSGN, monocyte/M phi accumulate in glomeruli via cell mediated immunity in addition to humoral immune mechanism resulting in glomerular hypercellularity, whereas in most chronic glomerulonephritis interstitial leucocyte infiltration, particularly helper T cells and monocyte/M phi may play an important role in the progression of glomerulonephritis.  相似文献   
94.
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   
95.
The amount of endothelial cell loss that occurs to the donor cornea during the trephination process was evaluated in 40 porcine eyes. A vital staining technique (alizarin red S and acid violet 19) was used to quantify the extent of endothelial damage and removal. Two types of corneal punches (Weck and H&I0 were used for trephination. The average amount of endothelial loss from the peripheral cornea was 7.9%, accounting for only a 3% loss of endothelial cells over the total surface area of the corneal button. a comparison of the Weck and H&I corneal punches showed no significant difference (P greater than 0.1) by Student's test for both endothelial cell damage and removal.  相似文献   
96.
Multicentricity of hepatocellular carcinoma (HCC) is considered, especially in patients with liver cirrhosis. This paper describes an operative case of a male patient with probable multicentric development of HCC in precirrhotic fibrosis. The main tumors inside the capsule were completely necrotic due to transarterial embolization (TAE). Histologic examination disclosed discrete tiny nodules of HCC that were not detected grossly. They showed highly differentiated trabecular arrangements: Edmondson I. A scirrhous type was noted in the center of the tumors. At the borders of the tumors the carcinoma cells exhibited replacing growth patterns and it was thought that they developed multicentrically. Partial resection must be performed as extensively as possible in a case such as the present one.  相似文献   
97.
98.
99.
Vibrio cholerae was isolated from the blood cultures of a neutropenic patient treated with chemotherapy for non-small-cell lung cancer. Attempts to isolate Vibrio spp. from a rectal swab and stool were unsuccessful. Piperacillin/tazobactam treatment resulted in eradication of the microorganism from the patient's blood. Although Vibrio spp. have occasionally been the source of infection in immunocompromised patients, this report describes the first case of non-0:1 Vibrio cholerae bacteremia in a neutropenic patient with a solid tumour. Electronic Publication  相似文献   
100.
PURPOSE: To compare, using a prospective, randomized controlled study, three methods of teaching a medical school parasitology course: computer-based instruction, traditional lecture-based instruction, and a combination of computer-based and lecture-based instruction. METHOD: A single class of the University of Utah School of Medicine was randomized into three study groups for the second-year parasitology course. The computer group (n = 29) used a locally developed interactive parasitology computer program; the lecture group (n = 32) had traditional lectures, and the combined group (n = 33) used both the computer program and lectures. Students' knowledge was assessed using a pretest, a final examination, and a posttest administered four months after the course. Students also used logs to track the amounts of time they spent studying. Their impressions and course evaluations were collected using a standardized course-evaluation form. RESULTS: The groups' scores on the pretest, final examination, and posttest were not statistically significantly different. Students in the computer group averaged 26.8 hours of studying over the two-week course compared with 32.1 hours in the lecture group and 32.7 hours in the combined group. The difference in study times between the computer and combined groups yielded a significant p value of 0.036. Students were generally positive about the course and the computer program. CONCLUSION: Students can learn parasitology from computer-based instruction as effectively as from traditional lecture-based instruction, and they can do so in less time.  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