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   992639篇
  免费   70707篇
  国内免费   1535篇
耳鼻咽喉   13737篇
儿科学   25784篇
妇产科学   24076篇
基础医学   140595篇
口腔科学   29235篇
临床医学   87116篇
内科学   196089篇
皮肤病学   19969篇
神经病学   78089篇
特种医学   38821篇
外国民族医学   84篇
外科学   162806篇
综合类   18661篇
现状与发展   1篇
一般理论   281篇
预防医学   66239篇
眼科学   22523篇
药学   76785篇
  3篇
中国医学   2226篇
肿瘤学   61761篇
  2021年   7408篇
  2019年   7589篇
  2018年   10959篇
  2017年   8459篇
  2016年   9252篇
  2015年   10562篇
  2014年   14468篇
  2013年   20619篇
  2012年   28933篇
  2011年   30043篇
  2010年   17562篇
  2009年   16759篇
  2008年   28700篇
  2007年   29829篇
  2006年   30453篇
  2005年   29238篇
  2004年   27985篇
  2003年   26895篇
  2002年   26051篇
  2001年   55202篇
  2000年   56923篇
  1999年   47351篇
  1998年   11343篇
  1997年   9943篇
  1996年   9981篇
  1995年   9268篇
  1994年   8580篇
  1993年   7863篇
  1992年   35726篇
  1991年   34118篇
  1990年   32913篇
  1989年   32034篇
  1988年   29163篇
  1987年   28389篇
  1986年   26428篇
  1985年   25282篇
  1984年   17991篇
  1983年   15289篇
  1982年   7925篇
  1979年   15879篇
  1978年   10687篇
  1977年   9122篇
  1976年   7933篇
  1975年   8671篇
  1974年   10524篇
  1973年   9900篇
  1972年   9394篇
  1971年   8879篇
  1970年   8469篇
  1969年   7956篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Excision of the rectum should take in account that the main lymphatic spread follows the cranial route and that dissection of the rectal wall should be performed across its adjacent anatomical lamellae. It is not clear whether an extensive pelvic dissection and high ligature of the inferior mesenteric artery are beneficial. Spontaneous or iatrogenic perforation of the tumour considerable increases the incidence of local recurrence. The frequency of postoperative urinary and sexual dysfunction ranges from 3.5-57% and 14-38% respectively. The reported surgical mortality averages 5-6%.  相似文献   
93.
Summary A case of bilateral congenital pseudarthrosis of the clavicle in a baby boy is described. The patient is fully asymptomatic, and no functional impairment is present. This is probably only the seventh case described of this rare congenital anomaly.  相似文献   
94.
Regional effects of craniotomy on cerebral circulation and metabolism, such as regional cerebral blood flow (rCBF), regional cerebral oxygen consumption (rCMRO2), regional oxygen extraction fraction (rOEF), and regional cerebral blood volume (rCBV) were examined by a PET (positron emission tomography) study concerning surgery that was performed on unruptured aneurysm patients. Eight patients with intracranial un-ruptured aneurysms were studied pre- and post-operatively by the 15O labelled-gas steady-state method, using HEADTOME-III. All patients underwent aneurysmal surgery performed by the transsylvian approach. There was a significant increase in the mean OEF values taken from the whole-brains of 8 patients, but there was not a significant change in CBF, CMRO2 or CBV. The increase in OEF was caused by decrease of O2 content, which was caused by post-operative decrease in the Hb value. So, this OEF increase was not the direct effect of craniotomy. In 2 patients, the rCBF and rCMRO2, in the fronto-temporal region (where craniotomy was performed) increased post-operatively. This regional effect suggests transient reactive hyperemia following compressive ischemia during the operative procedure, and metabolic demands for recovery of brain function. In 2 other patients, who had relatively low rCBFs during the pre-operative study, rCBF and rCMRO2 in the bi-frontal region had decreased more at the post-operative study. This change appears to have been caused by removal of cerebrospinal fluid and depression of the frontal lobe. From this study, it becomes evident that the regional effect of craniotomy on cerebral circulation and metabolism is not so great, when adequate microsurgical techniques are used.  相似文献   
95.
96.
97.
98.
99.
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   
100.
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   
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