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   3090篇
  免费   260篇
  国内免费   14篇
耳鼻咽喉   45篇
儿科学   52篇
妇产科学   47篇
基础医学   418篇
口腔科学   47篇
临床医学   246篇
内科学   676篇
皮肤病学   19篇
神经病学   315篇
特种医学   376篇
外科学   439篇
综合类   6篇
一般理论   1篇
预防医学   115篇
眼科学   52篇
药学   145篇
中国医学   5篇
肿瘤学   360篇
  2023年   43篇
  2022年   43篇
  2021年   88篇
  2020年   75篇
  2019年   107篇
  2018年   116篇
  2017年   75篇
  2016年   106篇
  2015年   112篇
  2014年   138篇
  2013年   147篇
  2012年   239篇
  2011年   242篇
  2010年   141篇
  2009年   145篇
  2008年   195篇
  2007年   187篇
  2006年   153篇
  2005年   163篇
  2004年   130篇
  2003年   134篇
  2002年   116篇
  2001年   34篇
  2000年   40篇
  1999年   35篇
  1998年   25篇
  1997年   22篇
  1996年   14篇
  1995年   9篇
  1994年   12篇
  1993年   13篇
  1992年   23篇
  1991年   25篇
  1990年   22篇
  1989年   23篇
  1988年   13篇
  1987年   28篇
  1986年   15篇
  1985年   9篇
  1984年   12篇
  1983年   6篇
  1982年   5篇
  1981年   5篇
  1980年   13篇
  1979年   6篇
  1978年   8篇
  1977年   6篇
  1972年   4篇
  1970年   5篇
  1967年   4篇
排序方式: 共有3364条查询结果,搜索用时 15 毫秒
1.
2.
3.
Objective: Descending and ascending aortomyoplasty are two surgical procedures intended to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). To date, there have been no studies comparing the two surgical techniques. The objective of this study was to compare coronary blood flow augmentation and afterload reduction as produced by descending and ascending aortomyoplasty counterpulsation Methods: Twenty-two mongrel dogs (18–35 kg) underwent IABP application (n=7), descending (n=8), or ascending (n=7) aortomyoplasty. Left anterior descending (LAD) coronary artery blood flow was measured using a Transonic Doppler flow probe. Left ventricular pressure as well as aortic pressures proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. Results: Descending aortomyoplasty induced higher elevation in the LAD blood flow during assisted beats (27% from 10.8±4 to 13.8±6 ml/min, P<0.001) than that induced by either ascending aortomyoplasty (19% from 11.7±5 to 14±5 ml/min, P<0.001) or IABP counterpulsation (18% from 8.6±3 to 10.2±4 ml/min, P<0.001). Conversely, while ascending aortomyoplasty reduced the left ventricular end-diastolic pressure by 16% (from 60±18 to 50±22 mmHg, P<0.001), similar to the 16% after load reduction achieved by the IABP counterpulsation, descending aortomyoplasty failed to induce afterload reduction. Conclusions: Descending aortomyoplasty produces higher coronary blood flow augmentation than either ascending aortomyoplasty or IABP. However, afterload reduction comparable to that achieved by IABP was observed only with ascending aortomyoplasty and not with descending aortomyoplasty.  相似文献   
4.

Background  

For patients suffering of recurrent breast cancer within the irradiated breast, generally mastectomy is recommended. The normal tissue tolerance does not permit a second full-dose course of radiotherapy to the entire breast after a second breast-conserving surgery (BCS). A novel option is to treat these patients with partial breast irradiation (PBI). This approach is based on the hypothesis that re-irradiation of a limited volume will be effective and result in an acceptable frequency of side effects. The following report presents a single center experience with intraoperative radiotherapy (IORT) during excision of recurrent breast cancer in the previously irradiated breast.  相似文献   
5.
Mycobacterium tuberculosis plays a major role in infertility, which is the commonest symptom of genital tuberculosis in women. From August 1987 to July 1988, 109 women presenting with infertility were investigated for tuberculosis. None had any other symptoms or signs of the disease. In all cases it was diagnosed by culture of M. tuberculosis in one or more of the 5 specimens (3 menstrual fluid specimens, endometrial tissue and peritoneal fluid) obtained from each woman. In addition Ziehl-Neelsen staining and histological examination were performed on all the specimens. Twenty-three patients (21%) had positive cultures for M. tuberculosis. Of the 26 positive specimens, 16 (69.6%) were menstrual fluid, 4 (17%) endometrial tissue and 6 (26%) peritoneal fluid (3 patients had more than one positive culture). Chest radiographs were normal in all cases. M. tuberculosis cultured in human tissue must be recognized as a pathogen and necessitates treatment. Selective screening procedures should be done to exclude genital tuberculosis as a cause of infertility.  相似文献   
6.
7.
Inhibition of protein synthesis can alter cellular responsiveness to the classical anticancer drugs. The in vitro response of Chinese hamster ovary (CHO) cells to cisplatin with or without sparsomycin (Sm) was studied with the use of [3H]leucine and [methyl-3H]thymidine incorporation and clonogenic assay. Pretreatment of exponentially growing CHO cells with 1 microgram Sm/ml for 3 or 5 hours decreased [3H]leucine incorporation by 20% and resulted in significant resistance to cisplatin (P = .005). Sm in a concentration of 10 micrograms/ml reduced [3H]leucine and [methyl-3H]thymidine incorporation after 3 hours by 92 and 84%, respectively, and resulted in potentiation of the cisplatin cytotoxicity (P = .004). This effect was the same in the case of nonproliferating cells (P = .005), while protection due to Sm (1 microgram/ml) was seen only during cell proliferation. Simultaneous incubation and postincubation with Sm proved to have much less or no potentiating effect on cisplatin. The mechanisms of both protection and potentiation are still not clear, but our data indicate that Sm is a promising drug for further studies on the modulation of the cancer cell response to classical anticancer drugs.  相似文献   
8.
9.
BACKGROUND: Although normally quiescent, the adult mammalian liver possesses a great capacity to regenerate after different types of injury. Major players in the regeneration process are mature residual cells, including hepatocytes, cholangiocytes and stromal cells. However, if the regenerative capacity of mature cells is impaired, hepatic progenitor cells (HPCs) are activated and expand into the liver parenchyma. Upon transit amplification, the progenitor cells generate new hepatocytes and biliary cells to restore liver homeostasis. AIMS/METHODS: To study the relationship between different histopathological parameters as well as their correlations with clinical parameters and outcome, we examined liver specimens from 74 patients with acute or subacute severe liver impairment by immunohistochemistry for CK7/CK19 (evaluation of HPCs activation/differentiation), Mib1(Ki 67)/P21 (evaluation of proliferative activity/proliferation arrest of hepatocytes) and hematoxylin and eosin (evaluation of hepatocyte loss). RESULTS: Of the 74 patients, 32% survived without transplantation, 14% died without transplantation and 54% were transplanted. Our results show that a threshold of 50% loss of hepatocytes, associated with significant decrease in the proliferative activity of remaining mature hepatocytes, is needed for extensive hepatic progenitor cell activation. Such activation is a sign of disease severity and occurs early (within 1 week) in the disease course. However, development of intermediate hepatocytes, suggesting HPCs differentiation towards mature hepatocytes, takes at least 1 week's time. We found a positive correlation between histopathological parameters (percentage hepatocyte loss, number of proliferating hepatocytes and number of HPCs) and clinical parameters of liver impairment such as model for end stage liver diseases (MELD). Surviving patients compared with those who either died or were transplanted had significantly less hepatocyte loss, less HPCs activation and more mature hepatocyte proliferative activity. Hepatocyte proliferative activity and degree of hepatocyte loss were the most important independent histopathological parameters in predicting outcome. CONCLUSION: Liver biopsy can provide important additional information in a patient with severe acute liver impairment.  相似文献   
10.
Over an 8-year period (1982-1989) 43 patients with subacute and chronic extradural haematomas were treated. The clinical picture of the patients, computed tomography (CT) as well as operative findings and prognosis were evaluated. The radiological picture as seen on CT was correlated with the time interval elapsing between initial trauma and surgery. Operative findings are discussed and the terms 'subacute' and 'chronic' are defined.  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