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   1015篇
  免费   41篇
  国内免费   39篇
耳鼻咽喉   13篇
儿科学   44篇
妇产科学   21篇
基础医学   96篇
口腔科学   21篇
临床医学   99篇
内科学   233篇
皮肤病学   23篇
神经病学   36篇
特种医学   179篇
外科学   118篇
综合类   19篇
预防医学   41篇
眼科学   10篇
药学   99篇
中国医学   4篇
肿瘤学   39篇
  2021年   9篇
  2018年   11篇
  2017年   9篇
  2015年   13篇
  2014年   18篇
  2013年   23篇
  2012年   18篇
  2011年   19篇
  2010年   21篇
  2009年   33篇
  2008年   21篇
  2007年   37篇
  2006年   28篇
  2005年   15篇
  2004年   20篇
  2003年   17篇
  2002年   21篇
  2001年   25篇
  2000年   24篇
  1999年   29篇
  1998年   53篇
  1997年   51篇
  1996年   43篇
  1995年   30篇
  1994年   28篇
  1993年   33篇
  1992年   15篇
  1991年   22篇
  1990年   15篇
  1989年   36篇
  1988年   24篇
  1987年   28篇
  1986年   21篇
  1985年   28篇
  1984年   23篇
  1983年   28篇
  1982年   16篇
  1981年   22篇
  1980年   20篇
  1979年   9篇
  1978年   19篇
  1977年   12篇
  1976年   10篇
  1975年   13篇
  1974年   7篇
  1973年   10篇
  1972年   11篇
  1971年   8篇
  1970年   10篇
  1965年   10篇
排序方式: 共有1095条查询结果,搜索用时 15 毫秒
1.
2.
3.
Dermatofibrosarcoma protuberans (DFSP) previously called Morbus Darier is an intermediate grade sarcoma with a fairly high rate of recurrence, it occurs most commonly on the trunk and extremities but may also occur in the head and neck region. Treatment of choice is wide excision. A 69-year-old female patient with a 57-year history of dermatofibrosarcoma protuberans is presented. The lesion appeared on the right forehead and both eyelids at the age of 12 years. The patient required 64 surgeries mostly for the head and neck lesions.  相似文献   
4.
Evaluation of serum levels of FSH, LH, prolactin, testosterone and oestradiol is not predictive of the increases of sperm count after varicocelectomy. Increased level of oestradiol reflects the lack of possibility of sperm motility increase after varicocelectomy.  相似文献   
5.
Oral pretreatment with aldosterone or corticosterone blocked the memory-enhancing effects of the calcium antagonist nimodipine, the ACE inhibitor captopril, the NMDA blocker CGP 37 849, and the glycine antagonist strychnine in a passive-avoidance test in mice. The memory-disturbing effects of phenobarbitone, diazepam, CGP 37 849 and scopolamine were not influenced by the hormonal pretreatment. These findings could indicate the involvement of a steroid-sensitive mechanism in drug-induced improvement of memory. In the light of clinical observations showing elevated cortisol levels in Alzheimer patients, the results might also explain why only a limited number of these patients respond to therapy with memory enhancers.  相似文献   
6.
7.
Normal and diseased isolated lungs: high-resolution CT   总被引:8,自引:0,他引:8  
  相似文献   
8.
Tumor targeting by an aptamer.   总被引:10,自引:0,他引:10  
Aptamers are small oligonucleotides that are selected to bind tightly and specifically to a target molecule. We sought to determine whether aptamers have potential for in vivo delivery of radioisotopes or cytotoxic agents. METHODS: TTA1, an aptamer to the extracellular matrix protein tenascin-C, was prepared in fluorescent and radiolabeled forms. After in vivo administration, uptake and tumor distribution of Rhodamine Red-X-labeled aptamer was studied by fluorescence microscopy. In glioblastoma (U251) and breast cancer (MDA-MB-435) tumor xenografts, biodistribution and imaging studies were performed using TTA1 radiolabeled with (99m)Tc. Tenascin-C levels and tumor uptake were studied in a variety of additional human tumor xenografts. To assess the effect of radiometal chelate on biodistribution, mercapto-acetyl diglycine (MAG(2)) was compared with diethylenetriaminepentaacetic acid and with MAG(2)-3,400-molecular-weight PEG (PEG(3,400)). RESULTS: Intravenous injection of fluorescent aptamer TTA1 produced bright perivascular fluorescence in a xenografted human tumor within 10 min. In the ensuing 3 h, fluorescence diffused throughout the tumor. Labeled with (99m)Tc, TTA1 displayed rapid blood clearance, a half-life of less than 2 min, and rapid tumor penetration: 6% injected dose (%ID)/g at 10 min. Tumor retention was durable, with 2.7 %ID/g at 60 min and a long-lived phase that stabilized at 1 %ID/g. Rapid tumor uptake and blood clearance yielded a tumor-to-blood ratio of 50 within 3 h. Both renal and hepatic clearance pathways were observed. Using the (99m)Tc-labeled aptamer, images of glioblastoma and breast tumors were obtained by planar scintigraphy. Aptamer uptake, seen in several different human tumors, required the presence of the target protein, human tenascin-C. Modification of the MAG(2) radiometal chelator dramatically altered the uptake and clearance patterns. CONCLUSION: TTA1 is taken up by a variety of solid tumors including breast, glioblastoma, lung, and colon. Rapid uptake by tumors and rapid clearance from the blood and other nontarget tissues enables clear tumor imaging. As synthetic molecules, aptamers are readily modified in a site-specific manner. A variety of aptamer conjugates accumulate in tumors, suggesting imaging and potentially therapeutic applications.  相似文献   
9.
10.
Shiota  Y; Wilson  JG; Harjes  K; Zanjani  ED; Tavassoli  M 《Blood》1993,82(5):1436-1444
The adhesion of hematopoietic progenitor cells to bone marrow stromal cells is critical to hematopoiesis and involves multiple effector molecules. Stromal cell molecules that participate in this interaction were sought by analyzing the detergent-soluble membrane proteins of GBI/6 stromal cells that could be adsorbed by intact FDCP-1 progenitor cells. A single-chain protein from GBI/6 cells having an apparent molecular weight of 37 Kd was selectively adsorbed by FDCP-1 cells. This protein, designated p37, could be surface-radiolabeled and thus appeared to be exposed on the cell membrane. An apparently identical 37- Kd protein was expressed by three stromal cell lines, by Swiss 3T3 fibroblastic cells, and by FDCP-1 and FDCP-2 progenitor cells. p37 was selectively adsorbed from membrane lysates by a variety of murine hematopoietic cells, including erythrocytes, but not by human erythrocytes. Binding of p37 to cells was calcium-dependent, and was not affected by inhibitors of the hematopoietic homing receptor or the cell-binding or heparin-binding functions of fibronectin. It is proposed that p37 may be a novel adhesive molecule expressed on the surface of a variety of hematopoietic cells that could participate in both homotypic and heterotypic interactions of stromal and progenitor 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