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   17761篇
  免费   834篇
  国内免费   95篇
耳鼻咽喉   180篇
儿科学   375篇
妇产科学   358篇
基础医学   2011篇
口腔科学   1483篇
临床医学   1182篇
内科学   4578篇
皮肤病学   438篇
神经病学   1457篇
特种医学   304篇
外科学   2541篇
综合类   91篇
一般理论   4篇
预防医学   1257篇
眼科学   390篇
药学   897篇
中国医学   103篇
肿瘤学   1041篇
  2024年   12篇
  2023年   134篇
  2022年   281篇
  2021年   591篇
  2020年   337篇
  2019年   534篇
  2018年   624篇
  2017年   411篇
  2016年   427篇
  2015年   531篇
  2014年   746篇
  2013年   905篇
  2012年   1486篇
  2011年   1603篇
  2010年   913篇
  2009年   746篇
  2008年   1220篇
  2007年   1395篇
  2006年   1187篇
  2005年   1032篇
  2004年   918篇
  2003年   758篇
  2002年   775篇
  2001年   98篇
  2000年   79篇
  1999年   85篇
  1998年   119篇
  1997年   99篇
  1996年   89篇
  1995年   58篇
  1994年   56篇
  1993年   48篇
  1992年   31篇
  1991年   30篇
  1990年   29篇
  1989年   16篇
  1988年   20篇
  1987年   16篇
  1986年   17篇
  1985年   17篇
  1984年   28篇
  1983年   19篇
  1982年   11篇
  1981年   24篇
  1980年   20篇
  1979年   10篇
  1978年   9篇
  1977年   18篇
  1976年   13篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Gangliocytic paragangliomas are rare tumors that almost exclusively occur within the second portion of the duodenum. Although these tumors generally have a benign clinical course, they have the potential to recur or metastasize to regional lymph nodes. The case report presented here describes a 57-year-old female patient with melena, progressive asthenia, anemia, and a mass in the second-third portion of the duodenum that was treated by local excision. The patient was diagnosed with a friable bleeding tumor. The histologic analysis showed that the tumor was a 4 cm gangliocytic paraganglioma without a malignant cell pattern. In the absence of local invasion or distant metastasis, endoscopic resection represents a feasible, curative therapy. Although endoscopic polypectomy is currently considered the treatment of choice, it is not recommended if the size of the tumor is > 3 cm and/or there is active or recent bleeding. Patients diagnosed with a gangliocytic paraganglioma should be closely followed-up for possible local recurrence.  相似文献   
2.
3.
4.
5.
6.
7.
8.
9.
BACKGROUND: Solid-organ transplantation has become the treatment of choice for patients with end-stage renal disease, end-stage liver failure, and some patients with type 1 diabetes mellitus. Similarly, surgical expertise and mechanical improvements have led to significant advances in laparoscopic surgery. Laparoscopic interventions are sometimes not pursued in transplant recipients due to the lack of strong supporting evidence for the use of laparoscopic techniques in these patients. METHODS: Using an extensive literature search, we review herein the available data on the utility of laparoscopic interventions in transplant recipients, with particular attention to the risks and benefits, indications, and contraindications for this complex patient population. RESULTS: Although randomized trials are few, multiple case reports indicate that many transplant recipients have benefited from laparoscopic interventions. CONCLUSION: The well-known benefits of laparoscopy could be extended to transplant recipients.  相似文献   
10.
Objectives. Acute unilateral ureteral obstruction (UUO) results in ipsilateral hydronephrosis characterized by a decrease in epidermal growth factor (EGF) mRNA expression and EGF protein levels in the distal renal tubules. UUO results in programmed cell death with increases in the characteristic markers of apoptosis. To suppress the apoptotic response during UUO, recombinant EGF was administered during renal obstruction and the ensuing molecular and histologic changes were studied.Methods. Mature Sprague-Dawley rats underwent left ureteral obstruction and the kidneys were harvested at 24, 48, and 72 hours. Markers of apoptosis included DNA laddering pattern on agarose gel electrophoresis, in situ gap labeling of fragmented DNA for quantitative apoptotic body determination, polyadenylated mRNA expression of SGP-2, and in situ hybridization for sulfated glycoprotein-2 (SGP-2) mRNA. Studies were repeated in rats following administration of 10, 20, and 40 μg of subcutaneous recombinant EGF on a daily basis after UUO.Results. Subcutaneous injection of EGF into unilaterally obstructed rats promotes renal tubular epithelial cell regeneration, as demonstrated by increased cortical mitotic activity. Systemic EGF supplementation in these unilaterally obstructed rats also resulted in a decrease in the intensity of the DNA laddering pattern associated with renal tubular apoptosis. An in situ labeling procedure to identify apoptotic nuclei in the ureterally obstructed kidneys revealed a 50% reduction in apoptosis after EGF administration. Northern blot analysis and in situ hybridization for SGP-2 mRNA or clusterin gene product also revealed a decreased expression in the obstructed and EGF-treated renal parenchyma.Conclusions. These data suggest that EGF, apart from its known role as a mitogenic substance for renal tubular epithelial cells, is also a critical in vivo renal cell survival factor for the developmentally mature kidney.  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