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   24957篇
  免费   1624篇
  国内免费   155篇
耳鼻咽喉   335篇
儿科学   613篇
妇产科学   545篇
基础医学   2920篇
口腔科学   897篇
临床医学   2286篇
内科学   5487篇
皮肤病学   506篇
神经病学   1430篇
特种医学   627篇
外国民族医学   6篇
外科学   3340篇
综合类   625篇
一般理论   27篇
预防医学   2054篇
眼科学   840篇
药学   2421篇
  1篇
中国医学   249篇
肿瘤学   1527篇
  2024年   37篇
  2023年   312篇
  2022年   881篇
  2021年   1348篇
  2020年   846篇
  2019年   1080篇
  2018年   1244篇
  2017年   874篇
  2016年   967篇
  2015年   990篇
  2014年   1339篇
  2013年   1545篇
  2012年   2132篇
  2011年   2199篇
  2010年   1271篇
  2009年   960篇
  2008年   1442篇
  2007年   1285篇
  2006年   1110篇
  2005年   955篇
  2004年   792篇
  2003年   699篇
  2002年   587篇
  2001年   180篇
  2000年   191篇
  1999年   172篇
  1998年   100篇
  1997年   70篇
  1996年   68篇
  1995年   62篇
  1994年   48篇
  1993年   57篇
  1992年   72篇
  1991年   60篇
  1990年   74篇
  1989年   54篇
  1988年   55篇
  1987年   38篇
  1986年   49篇
  1985年   43篇
  1984年   43篇
  1983年   43篇
  1982年   39篇
  1981年   23篇
  1979年   33篇
  1978年   32篇
  1977年   24篇
  1976年   34篇
  1974年   28篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
BACKGROUND: Hemangioma is the most common tumor of infancy. Although it has a basically benign nature and usually spontaneously regresses, a small percentage (5%) have complications that need treatment. Many different therapeutic modalities can be used in this tumor. OBJECTIVE: To investigate the effect of a new method of treatment (intralesional bleomycin injection) in complicated hemangiomas. MATERIALS AND METHODS: In the Department of Radiation Oncology at Nemazee Hospital in Shiraz, Iran, from April 1992 to October 1998, 32 patients with complicated hemangioma were treated with four to six courses of direct injection of bleomycin into the lesion. RESULTS: After a minimum follow-up of 6 years, there was 70 to 100% regression in 18 patients, 50 to 70% in 7 cases, and less than 50% reduction in 7 patients. CONCLUSION: Intralesional injection of bleomycin is an easy, safe, and effective therapeutic modality in complicated cutaneous hemangiomas.  相似文献   
72.
73.
Device-induced thrombogenesis was studied in an in vitro model using human blood circulated through an artificial ventricle. A new constant pressure filtration technique was used to detect circulating microemboli, the activated partial thromboplastin time (APTT) test was used to monitor the blood for the presence of anticoagulant activity of heparin, and hemolysis was quantified by measuring the plasma free hemoglobin level. Circulation of blood through a 20-ml stroke volume pneumatically driven ventricle for 6-9 h resulted in a significant reduction of APTT, indicating the loss of the anticoagulant effect of heparin. Microemboli concentration was minimal until the APTT decreased below 125 s, at which time the microemboli concentration increased rapidly. This was presumed to be due to the formation of thrombi following a decrease in heparin activity. A significant increase in hemolysis was also noted when blood was pumped. None of these changes was noted in the nonpumped control blood. Spontaneous loss of heparin activity in blood circulated by a pneumatically driven pump may have clinical implications and may help understanding of the problems associated with device-induced thrombogenesis.  相似文献   
74.
75.
76.
Approximately 5% of Americans over age 65, or 1.5 million individuals, currently reside in the nations's 20,000 nursing homes. The authors present material that lead to three conclusions about this population. First, nutritional deficiencies are common underlying causes of adverse clinical outcomes. Second, nutritional deficiencies are frequently not recognized. Third, opportunities for preventing or correcting undernutrition exist, provided that the significant and reversible nature of the nutrient deficiencies are identified.  相似文献   
77.
78.
79.
The effects of tetracaine (10–50 M) and ryanodine (0.1–10 M) were tested on the slow outward K+ current (I so) and the mechanical tension of isolated frog muscle fibres in a voltage-clamp device (double mannitol-gap) connected to a mechanoelectric transducer. In the concentration range tested, both drugs induced a simultaneous inhibition of tension and current. In all cases the effect on tension was twice that on current. The tetracaine-induced current and tension blocks were fully reversible and dose-dependent. In contrast the ryanodine effects on current and tension were not reversible and did not exhibit a dose dependence except for the delay before the onset of the response, which was shortened when the concentration was raised. Linear regression analysis of the time-dependent and dose-dependent effects of both drugs indicated a strong correlation between the decreases in tension and current. It is concluded that the slow outward current is partly under the control of the Ca2+ release from sarcoplasmic reticulum during contraction.  相似文献   
80.
Osteoclast-rich undifferentiated carcinomas of the urinary tract.   总被引:2,自引:0,他引:2  
Osteoclast-like giant-cell neoplasms of the urinary tract are rare. They are composed of ovoid or spindle-shaped mononuclear cells with evenly spaced osteoclast-like giant cells. Terminology, histogenesis, and biologic behavior of these tumors remain controversial. Six cases of osteoclast-like giant-cell neoplasms of the urinary tract were identified from the consultation files of two of the authors. Patients were all male and elderly (range 65-82), with the exception of one 39-year-old male. In all, 3/6 tumors developed in the bladder and 3/6 in the renal pelvis. Size ranged from 5 to 11 cm. One bladder and three renal pelvis tumors were high stage (pT3) at time of presentation. Adjacent to the osteoclast-like giant-cell neoplasm in the same specimen, all patients had urothelial carcinoma in situ and/or high-grade papillary urothelial carcinoma. Multinucleated cells had identical morphological and immunohistochemical properties of osteoclasts; positive for CD-68, LCA, CD51 and CD54, and negative for cytokeratins and EMA. Varying percentages of mononuclear cells expressed alpha-smooth muscle actin (4/6), desmin (1/6), S-100 (4/6), LCA (2/6) and CD68 (6/6). However, mononuclear cells were also positive for epithelial markers in 4/6 tumors (cytokeratins AE-1/AE-3, Cam 5.2, CK7 and/or EMA). p53 stained mononuclear tumor cells in three cases, paralleling the staining on the accompanying urothelial carcinoma. Ki-67 stained mononuclear tumor cells, but not osteoclast-like giant cells. Follow-up data were available in five cases. One patient developed recurrence of noninvasive urothelial carcinoma and is still alive. Four patients were dead due to disease within 15 months, three with distant metastases. The intimate association of these tumors with urothelial carcinoma along with their immunohistochemical profile supports an epithelial origin for the mononuclear cells and non-neoplastic reactive histiocytic lineage for the osteoclast-like giant cells.  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