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   149055篇
  免费   32096篇
  国内免费   2398篇
耳鼻咽喉   5176篇
儿科学   5407篇
妇产科学   2447篇
基础医学   2962篇
口腔科学   1509篇
临床医学   26589篇
内科学   46964篇
皮肤病学   7469篇
神经病学   14693篇
特种医学   6342篇
外科学   40823篇
综合类   244篇
现状与发展   72篇
预防医学   6940篇
眼科学   3389篇
药学   903篇
中国医学   7篇
肿瘤学   11613篇
  2024年   684篇
  2023年   4788篇
  2022年   1193篇
  2021年   3087篇
  2020年   6022篇
  2019年   2155篇
  2018年   7380篇
  2017年   7331篇
  2016年   8413篇
  2015年   8399篇
  2014年   15465篇
  2013年   15574篇
  2012年   5382篇
  2011年   5390篇
  2010年   10291篇
  2009年   14202篇
  2008年   5705篇
  2007年   3936篇
  2006年   6429篇
  2005年   3691篇
  2004年   2969篇
  2003年   1936篇
  2002年   2026篇
  2001年   3783篇
  2000年   2993篇
  1999年   3196篇
  1998年   3637篇
  1997年   3454篇
  1996年   3351篇
  1995年   3204篇
  1994年   1934篇
  1993年   1558篇
  1992年   1368篇
  1991年   1403篇
  1990年   1050篇
  1989年   1170篇
  1988年   1012篇
  1987年   846篇
  1986年   880篇
  1985年   713篇
  1984年   545篇
  1983年   517篇
  1982年   511篇
  1981年   398篇
  1980年   358篇
  1979年   306篇
  1978年   328篇
  1977年   396篇
  1975年   278篇
  1972年   302篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
944.
SUMMARY The study explored the incidence of clinical feminisation and the sex hormone levels of 18 Nigerian patients with liver cirrhosis (LC) alone and 18 patients with LC and hepatocellular carcinoma (HCC). The incidence (11%) of clinical feminisation in Nigerian patients was lower than values reported from other countries and there was no association between feminising signs and the sex hormone levels of the patients. Plasma oestradiol and sex hormone-binding globulin (SHBG) levels were significantly higher and testosterone lower in patients with liver diseases than in 18 age-matched normal controls. Serum concentrations of oestradiol were also found to be significantly higher in patients with LC alone than in those with LC and HCC. A possible promotive role for oestrogens in the development of HCC from the cirrhotic liver is discussed.  相似文献   
945.
946.
The pancreas gives rise to a remarkable variety of neoplasms other than ductal adenocarcinoma. Although no individual type of tumor in this category is prevalent enough to qualify as common, most types are currently encountered with a frequency far greater than that in decades of the recent past. This change is largely the result of the expanded use of contemporary abdominal imaging. The unusual tumors of the pancreas vary greatly in their biologic behavior and, accordingly, in their clinical consequences and therapeutic requirements. Accurate diagnosis, therefore, can be of considerable clinical relevance. Not only is it worthwhile to distinguish one type of unusual pancreatic tumors from another, it is perhaps of even greater consequence to distinguish the unusual tumors from ordinary pancreatic adenocarcinomas. The goals of this discussion are to expand radiologic awareness of these uncommon but interesting pancreatic neoplasms and to increase familiarity with their diagnostically salient features.  相似文献   
947.
948.
949.
Background: Percutaneous closed needle biopsy of musculoskeletal neoplasms has gained in popularity. However, it remains controversial whether or not to resect the needle tract for fear of a local recurrence. A single published case report exists, noting the lone tract recurrence of an extremity skeletal osteosarcoma. Methods: We report on three additional individuals who demonstrated that tract local recurrences may occur after a closed needle biopsy for nonosteosarcoma, nonextremity sarcomas. For perspective, the world literature is reviewed to identify tract recurrences for other malignancies and the results of needle biopsy in musculoskeletal neoplasms. Results: Eighty-nine percent of needle tract local recurrences occur when carcinomas are subjected to biopsy, as reported in the literature. Forty-seven cases since 1950 are described representing essentially all tumor types. The nature of musculoskeletal neoplasms makes closed biopsy more difficult than for softer, more homogeneous, and easier to access neoplasms. Conclusions: Local recurrences of sarcoma may occur in closed needle biopsy tracts. Strong consideration should be given to open biopsy and tract resection.  相似文献   
950.
Background: The overexpression of p53 has been found to be correlated with prognosis of some carcinomas, including gastric cancer, but no studies have reported on its relationship to the location of gastric cancer. In the present study, we compared the p53 expression of proximal and distal gastric cancer concerning histopathology and prognosis. Methods: A total of 170 tumors in the patients with proximal (80 cases) and distal (90 cases) gastric cancer were studied by immunohistochemical methods. Results: p53 immunopositivity was detected in 28.8% of all tumors. The p53-positive expression in proximal gastric cancer was higher than in distal gastric cancer (38.8% vs. 20.0%, p<0.05). A 5-year survival analysis showed that there is no significant difference between tumors that are p53 positive and p53 negative. No correlation was found between p53 expression and histopathology of gastric cancer. Conclusion: p53 nuclear staining is not useful as a prognostic indicator or as a parameter in gastric cancer.  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