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   1189篇
  免费   196篇
  国内免费   13篇
耳鼻咽喉   16篇
儿科学   57篇
妇产科学   58篇
基础医学   294篇
口腔科学   18篇
临床医学   115篇
内科学   190篇
皮肤病学   13篇
神经病学   83篇
特种医学   104篇
外科学   131篇
综合类   36篇
一般理论   1篇
预防医学   89篇
眼科学   6篇
药学   88篇
肿瘤学   99篇
  2021年   14篇
  2019年   12篇
  2016年   15篇
  2015年   22篇
  2014年   28篇
  2013年   29篇
  2012年   41篇
  2011年   44篇
  2010年   30篇
  2009年   32篇
  2008年   39篇
  2007年   52篇
  2006年   43篇
  2005年   30篇
  2004年   36篇
  2003年   30篇
  2002年   46篇
  2001年   38篇
  2000年   30篇
  1999年   36篇
  1998年   35篇
  1997年   26篇
  1996年   34篇
  1995年   41篇
  1994年   23篇
  1993年   18篇
  1992年   30篇
  1991年   19篇
  1990年   37篇
  1989年   44篇
  1988年   53篇
  1987年   51篇
  1986年   41篇
  1985年   32篇
  1984年   30篇
  1983年   19篇
  1982年   16篇
  1981年   9篇
  1980年   9篇
  1979年   14篇
  1978年   11篇
  1977年   8篇
  1976年   10篇
  1975年   14篇
  1974年   15篇
  1973年   10篇
  1972年   20篇
  1971年   10篇
  1970年   9篇
  1968年   11篇
排序方式: 共有1398条查询结果,搜索用时 15 毫秒
1.
Metallic stents have been used in the management of prostatic disease in patients unfit for surgery. A variety of stents have become available but the optimum design and metal of construction has not yet been defined. This study examined one of the potential complications of stent insertion by demonstrating that they are susceptible to encrustation. Using an in vitro model it compares the ability of the different materials used in their construction to resist this encrustation. Titanium appears less able to resist deposition than the other metals examined. The long-term complication of encrustation may inhibit the use of some of these stents.  相似文献   
2.
3.
4.
硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用   总被引:8,自引:1,他引:7  
研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。  相似文献   
5.
6.
7.
Nasal, tracheal and bronchoalveolar injuries resulting from acute ozone exposure of rats were investigated by permeability changes. 99mTc-labeled diethylenetriaminepentaacetate (DPTA) and 125I-labeled bovine serum albumin (BSA) were selectively instilled into localized airway regions of anesthetized rats exposed to 0.8 ppm 03 or clean air for 2 h. Transmucosal transfer of the radiolabeled tracers was detected by counting the radioactivity in blood samples collected at short postinstillation time intervals. Permeability measurements were made on d 0, 1, and 2 after O3 exposure to analyze the extent and persistence of tissue injury in the nasal, tracheal, and bronchoalveolar regions. Normal mucosal permeability was low in nose, intermediate in bronchoalveolar zone, and high in trachea. The O3-related injury, reflected by elevated permeability, was substantial in the trachea and bronchoalveolar zone but was minimal in the nose immediately after the exposure. Abnormal permeability persisted for less than 24 h in the trachea but for more than 24 h in the bronchoalveolar zone. The results are consistent with the properties of O3 of causing greater injury in the smaller airways and the alveolar zone than in the trachea.  相似文献   
8.
A series of 50 specimens of Hodgkin's disease and 10 of reactive follicular hyperplasia were examined by means of indirect immunoperoxidase staining with a monoclonal antibody AGF 4.48: this is known to bind to 3-fucosyl-N-acetyllactosamine, which, in particular, is expressed by granulocyte series cells. Most Reed-Sternberg and many Hodgkin's cells were labelled by the antibody after pretreatment with neuraminidase. Routinely processed paraffin wax embedded sections proved suitable for staining. The findings were comparable with those reported by others with monoclonal antibodies to various other granulocyte markers. This technique is of potential diagnostic value.  相似文献   
9.
Immunoglobulin (Ig) was demonstrated in paraffin sections of 12 trephine bone marrow biopsies by means of the unlabelled antibody peroxidase-antiperoxidase (PAP) method. The Ig-containing cells, which were counted with the Reichert-Jung (Kontron) MOP-AMO3 user-controlled image-analyser, were found to constitute approximately 4·2% of all the nucleated cells in the marrow, a figure significantly higher than those reported by previous workers.  相似文献   
10.
The study investigates the correlation between oocyte maturity and fertilization and a variety of hormonal parameters in follicular fluid and ovarian granulosa cells. A methodology for purification of granulosa cells from contaminating blood cells is also established. A total of 63 follicular aspirates were collected at oocyte retrieval from 30 women superovulated using the long luteinizing hormone- releasing hormone (LHRH analogue)/human menopausal gonadotrophin regimen. Oestradiol, progesterone, testosterone and human chorionic gonadotrophin (HCG) were quantified in follicular fluid and granulosa cells were immunostained for human chorionic gonadotrophin. Immunopurification of granulosa cells from contaminating blood cells was performed. HCG in follicular fluid was significantly high in follicles yielding immature (grade 3) oocytes (P=0.002); there was no correlation with fertilization. Aspirates from follicles containing mature (grade 1) oocytes and oocytes that subsequently fertilized had significantly more granulosa cells immunobound to HCG (P < 0.001, P=0.02). Moreover, the immunomagnetic purification technique provided >98% pure population of granulosa cells. The data demonstrate that HCG in follicular fluid and on granulosa cells may help to predict oocyte maturity and fertilization. Furthermore, immunomagnetic beads provide a reliable procedure for the purification of ovarian granulosa 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