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   3600篇
  免费   271篇
  国内免费   9篇
耳鼻咽喉   21篇
儿科学   107篇
妇产科学   105篇
基础医学   362篇
口腔科学   34篇
临床医学   740篇
内科学   630篇
皮肤病学   38篇
神经病学   248篇
特种医学   117篇
外科学   521篇
综合类   79篇
一般理论   13篇
预防医学   387篇
眼科学   100篇
药学   244篇
中国医学   2篇
肿瘤学   132篇
  2023年   19篇
  2022年   31篇
  2021年   67篇
  2020年   43篇
  2019年   69篇
  2018年   54篇
  2017年   51篇
  2016年   59篇
  2015年   64篇
  2014年   80篇
  2013年   130篇
  2012年   146篇
  2011年   191篇
  2010年   99篇
  2009年   85篇
  2008年   166篇
  2007年   187篇
  2006年   189篇
  2005年   224篇
  2004年   162篇
  2003年   178篇
  2002年   145篇
  2001年   104篇
  2000年   103篇
  1999年   97篇
  1998年   31篇
  1997年   39篇
  1996年   26篇
  1995年   29篇
  1994年   34篇
  1993年   32篇
  1992年   86篇
  1991年   74篇
  1990年   72篇
  1989年   73篇
  1988年   65篇
  1987年   54篇
  1986年   39篇
  1985年   56篇
  1984年   32篇
  1983年   33篇
  1979年   33篇
  1978年   24篇
  1977年   21篇
  1976年   22篇
  1975年   18篇
  1974年   24篇
  1973年   25篇
  1972年   22篇
  1970年   19篇
排序方式: 共有3880条查询结果,搜索用时 15 毫秒
21.
Abdominal complications of intestinal surgery are an important cause of postoperative morbidity and mortality. We define early complications as those occurring within the first 30 days after surgery. The radiological contribution towards prompt and accurate diagnosis of common complications is discussed and the radiologist's role in non-operative management is outlined.  相似文献   
22.
23.
24.
The 1896 precore (PC) mutation is the most frequent cause of hepatitis B virus e-antigen (HBeAg)-negative chronic hepatitis B virus (HBV) infection. Detection of the 1896 PC mutation has application in studies monitoring antiviral therapy and the natural history of the disease. Identification of this mutation is usually performed by direct sequencing, which is both costly and laborious. The aim of this study was to develop a rapid, high-throughput assay to detect the 1896 PC mutation using real-time PCR and molecular-beacon technology. The assay was initially standardized on oligonucleotide targets and plasmids containing the wild-type (WT) and PC mutation and then tested on plasma samples from children with HBV DNA of >10(6) copies/ml. Nine individuals were HBeAg negative and suspected to harbor HBeAg mutations, while 12 children were HBeAg positive and selected as controls. Ninety percent (19 of 21) of plasma samples tested with molecular beacons were in complete agreement with sequencing results. The remaining 10% (2 of 21) of samples were identified as heterogeneous mixtures of WT and mutant virus by molecular beacons, though sequencing found only a homogeneous mutant in both cases. Overall, the 1896 PC mutation was detected by this assay in 55.5% of the children with HBeAg-negative infection. In summary, this assay is a rapid, sensitive, and specific technique that effectively discriminates WT from 1896 PC mutant HBV and may be useful in clinical and epidemiological studies.  相似文献   
25.
26.
27.
28.
Guinea pigs were sensitized by intraperitoneal injection of ovalbumin, 10 micrograms mixed with 100 mg A1(OH)3 in saline. On days 15-30 sensitized guinea pigs were challenged with ovalbumin aerosol (0.5 mg/ml, 30 s, 15 psi) which produced immediate asthmatic responses characterized by dyspnea, convulsions, and some deaths during the first 14 min. Twenty to 24 h later the animals were sacrificed with an overdose of pentobarbital, and lungs, bronchi, and lower trachea were dissected and fixed in 10% neutral buffered formalin. Histopathological examination of randomly coded tissues of the respiratory tract revealed a pulmonary eosinophilic cellular infiltrate in the epithelium/subepithelium of trachea, bronchi, and bronchioles as well as the peribronchial, peribronchiolar, and perivascular areas of the lungs. Oral administration of mepyramine (10 mg/kg) 2 h before aeroallergen challenge provided complete protection against immediate asthmatic responses and prevented deaths during the first 14 min without influencing the late phase associated lung eosinophilic cellular infiltrate. The immediate asthmatic responses were not influenced by methylprednisolone (30 mg/kg) administered orally 24 and 2 h before aeroallergen challenge. Following an additional dose of methylprednisolone 4 h after challenge, there was a significant inhibition of pulmonary eosinophilia (30 mg/kg; -24 h, -2 h, and +4 h). These observations suggest that histamine is the principal mediator of immediate asthma attacks in guinea pigs. Methylprednisolone may be acting by inhibiting the production of eosinophil chemotactic factor of anaphylaxis (platelet-activating factor or leukotriene B4) from the alveolar macrophages, T lymphocytes, and perhaps other cells, thus preventing pulmonary eosinophilia.  相似文献   
29.
The ability of azelastine to influence allergic bronchial eosinophil infiltration in guinea pigs was studied. Aeroallergen challenge of actively sensitized guinea pigs produces eosinophil infiltration in bronchoalveolar lavage fluid collected 20-24 h after aeroallergen exposure. Azelastine and methylprednisolone, administered orally 2 h before challenge, inhibited eosinophilic infiltration yielding the ED50s of 1.55 and 4.48 mg/kg, respectively. WEB-2086, a platelet-activating factor antagonist (3 mg/kg), and theophylline, a phosphodiesterase inhibitor (30 mg/kg), also suppressed allergic bronchial infiltration of eosinophils by 44%. The data obtained in this study demonstrate that azelastine exerts direct bronchial anti-inflammatory activity in guinea pigs.  相似文献   
30.
Cryopreserved spermatozoa from men having treatment for lymphoma or testicular tumour have been reported to function sub-optimally. We report on three successful pregnancies following gamete intra-Fallopian transfer (GIFT) using such cryopreserved sperm samples. In one case, ovum donation was required since the woman had premature ovarian failure.  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