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   1778篇
  免费   150篇
  国内免费   12篇
耳鼻咽喉   22篇
儿科学   43篇
妇产科学   7篇
基础医学   215篇
口腔科学   35篇
临床医学   150篇
内科学   499篇
皮肤病学   26篇
神经病学   56篇
特种医学   103篇
外科学   284篇
综合类   77篇
预防医学   99篇
眼科学   45篇
药学   87篇
中国医学   25篇
肿瘤学   167篇
  2023年   12篇
  2022年   15篇
  2021年   44篇
  2020年   35篇
  2019年   30篇
  2018年   56篇
  2017年   31篇
  2016年   32篇
  2015年   57篇
  2014年   51篇
  2013年   56篇
  2012年   92篇
  2011年   119篇
  2010年   62篇
  2009年   58篇
  2008年   85篇
  2007年   99篇
  2006年   102篇
  2005年   75篇
  2004年   100篇
  2003年   104篇
  2002年   64篇
  2001年   56篇
  2000年   52篇
  1999年   39篇
  1998年   24篇
  1997年   20篇
  1996年   22篇
  1995年   18篇
  1994年   15篇
  1993年   15篇
  1992年   24篇
  1991年   26篇
  1990年   27篇
  1989年   25篇
  1988年   27篇
  1987年   28篇
  1986年   26篇
  1985年   17篇
  1984年   17篇
  1983年   9篇
  1982年   6篇
  1981年   7篇
  1980年   7篇
  1979年   7篇
  1977年   10篇
  1976年   4篇
  1974年   5篇
  1972年   7篇
  1971年   7篇
排序方式: 共有1940条查询结果,搜索用时 15 毫秒
1.
The present study aimed to determine the alterations of antioxidant activities in erythrocytes from patients with nonsmall cell lung carcinoma (NSCLC). A comparative study of the systemic antioxidant activities in red blood cell lysate from subjects with NSCLC and healthy control subjects was conducted. The antioxidants catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured using chemical kinetic reactions under spectrophotometry. In total, 189 cases of mostly advanced-stage IIIB or stage IV NSCLC and 202 healthy controls were studied. In subjects with lung cancer, there was similar catalase activity, lower SOD activity (median (interquartile range) 13.4 (9.0-27.2) versus 48.7 (27.0-64.3) U x (ghaemoglobulin(Hb)(-1)), and higher GPx activity (175.2 (126.6-288.3) versus 49.2 (39.5-59.2) mU x (gHb)(-1)) compared with controls. The antioxidant activities in lung cancer subjects were not associated with age, sex, smoking status, or tumour cell types. However, more advanced disease (stage IV compared with stage IIIB) was associated with lower SOD activity. Using multivariable analysis, the presence of lung cancer independently predicted SOD and GPx activities. In conclusion, nonsmall cell lung carcinoma in Chinese subjects is associated with alterations in systemic antioxidant activities, which may play an important role in carcinogenesis.  相似文献   
2.
A 44-year-old female with Cushing's disease associated with a pituitary macroadenoma was treated with cyproheptadine, 24 mg per day, after partial surgical resection of the tumor. A large residual tumor remained. There was no clear suppression of serum and urinary cortisol during therapy, but both levels rose markedly to beyond pre cyproheptadine levels, on withdrawal of the drug. This is the first report on the use of cyproheptadine in Cushing's disease associated with a pituitary macroadenoma. The response in this patient indicates an influence of cyproheptadine on ACTH secretion by the macroadenoma.  相似文献   
3.
目的 大量富集三裂叶蟛蜞菊倍半萜内酯A,B(WTA,WTB)。方法 采用气相色谱法测定WTA和WTB,并以WTA和WTB的含量、洗脱率、精制度为考察指标,研究D101大孔树脂吸附WTA和WTB的工艺条件及参数。结果 通过大孔树脂吸附后,WTA和WTB的洗脱率达90%,50%乙醇洗脱部分中WTA和WTB的含量为总固物的4.01%~4.09%。结论 可以采用大孔树脂富集WTA和WTB。  相似文献   
4.
5.
6.
Sequential contrast-enhanced MR imaging of the penis   总被引:1,自引:0,他引:1  
Kaneko  K; De Mouy  EH; Lee  BE 《Radiology》1994,191(1):75
  相似文献   
7.
8.
The proliferative activity of gastric cancer cells with endocrine features was evaluated in five cases by means of a double-immunostaining procedure. The endocrine cells were recognized by a monoclonal antibody to chromogranin A (CGA) and the proliferative activity by a monoclonal antibody to proliferating cell nuclear antigen (PCNA). With the use of two different chromogens it was easy to determine whether CGA was located in the cytoplasm and whether PCNA was located in the nucleus of the same section. The CGA-positive endocrine cells of the normal gastric antral mucosa could be readily distinguished from the PCNA-positive cells scattered in the mucosal neck zones. Over 1,000 CGA-positive cancer cells were counted per case. A few cells (average, less than 1.0%) exhibited faint nuclear staining with anti-PCNA; in no instance was unequivocal PCNA reactivity demonstrable in the gastric cancer cells with endocrine differentiation. By contrast, the PCNA reaction was positive in one fourth to one third of the other cancer cells. These observations suggest that gastric cancer cells with endocrine features are differentiated and do not participate in the cell cycle.  相似文献   
9.
10.
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