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   11000篇
  免费   1149篇
  国内免费   46篇
耳鼻咽喉   87篇
儿科学   413篇
妇产科学   217篇
基础医学   1358篇
口腔科学   344篇
临床医学   1245篇
内科学   2012篇
皮肤病学   141篇
神经病学   1041篇
特种医学   431篇
外科学   1714篇
综合类   392篇
一般理论   30篇
预防医学   944篇
眼科学   176篇
药学   909篇
中国医学   4篇
肿瘤学   737篇
  2021年   109篇
  2020年   94篇
  2019年   138篇
  2018年   166篇
  2017年   117篇
  2016年   116篇
  2015年   132篇
  2014年   246篇
  2013年   347篇
  2012年   433篇
  2011年   442篇
  2010年   248篇
  2009年   266篇
  2008年   447篇
  2007年   513篇
  2006年   460篇
  2005年   508篇
  2004年   451篇
  2003年   420篇
  2002年   383篇
  2001年   418篇
  2000年   369篇
  1999年   352篇
  1998年   154篇
  1997年   119篇
  1996年   131篇
  1995年   115篇
  1994年   124篇
  1993年   130篇
  1992年   294篇
  1991年   266篇
  1990年   266篇
  1989年   267篇
  1988年   255篇
  1987年   260篇
  1986年   245篇
  1985年   241篇
  1984年   177篇
  1983年   150篇
  1982年   134篇
  1981年   113篇
  1980年   85篇
  1979年   123篇
  1978年   89篇
  1977年   78篇
  1976年   101篇
  1975年   91篇
  1974年   95篇
  1973年   117篇
  1972年   95篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
A method has been developed to compare gastrointestinal (GI) transit time after intrathecal (i.t.) drug injection in the rat. Each animal had a catheter implanted in the i.t. space. Eight rats, on three separate occasions, had either i.t. morphine 16 micrograms kg-1 (in 50 microliters) or intraperitoneal (i.p.) morphine (0.1%) 7.5 mg kg-1 or i.t. saline (50 microliters). The dose of morphine was the ED50 for analgesia by each route. After halothane and oxygen anaesthesia, 10 steel balls and 1 ml of contrast medium were placed into the stomach, the whole procedure being completed within 5 min. Radiographs were taken at 5 min, 3, 6 and 24 h, and the number of balls in the stomach, small and large intestine were counted. The inhibitory effect of i.t. or i.p. morphine on gut motility caused an equally significant delay at 6 h. In a separate series of eight rats the delay by i.t. morphine could be completely antagonized by i.p. naloxone 1 mg kg-1. Thus, i.t. morphine in an analgesic dose even though smaller than the i.p. dose has a similar inhibitory effect on GI tract motility in the rat. This method would enable comparisons on GI transit to be made between a variety of intrathecally administered drugs.  相似文献   
23.
BACKGROUND: Prior treatment with local hyperthermia has been shown to prevent mast cell degranulation and leucocyte histamine release, and to reduce mortality and cellular infiltrates in a model of acute lung injury. Local hyperthermia is effective in reducing the symptoms of the common cold and perennial and seasonal allergic rhinitis, nasal patency also being improved in rhinitis. It is possible that these effects are mediated by common anti-inflammatory mechanisms, and that this treatment may be effective in the treatment of asthma. The effect of prior local hyperthermia on the response to exercise challenge and histamine bronchoprovocation was therefore examined. METHODS: In a randomised, double blind, placebo controlled, crossover study, 10 asthmatic subjects with exercise induced asthma used machines delivering 40 1/minute of fully humidified air at either 42 degrees C (active treatment) or 31 degrees C (placebo treatment) for 30 minutes' tidal breathing. For each pretreatment, at two week intervals they underwent exercise challenges starting one and 24 hours after starting the inhalations. After a further two weeks the protocol was repeated with histamine substituted for the exercise challenges. RESULTS: The mean (SE) maximum percentage fall in forced expiratory volume in one second (FEV1) was significantly lower one hour after treatment with air at 42 degrees C (30.8% (3.1%)) than after treatment with air at 31 degrees C (22.3% (2.9%)). There was no significant effect on exercise challenge at 24 hours, or on histamine challenge at either time point, though there were nonsignificant trends towards protection with exercise at 24 hours and with histamine at one hour. CONCLUSION: In asthmatic subjects the response to exercise challenge is significantly attenuated one hour after treatment with local hyperthermia. This treatment warrants further investigation in the treatment of clinical asthma and other inflammatory disorders.  相似文献   
24.
We have described two children with multiple cutaneous granular cell tumors (GCT) and have reviewed the literature. Multiple tumors of the skin are relatively rare, especially in children, with only 18 pediatric cases previously reported. Surgical excision of rapidly growing or symptomatic lesions is the treatment of choice. In these two children with multiple GCT, three lesions were excised. Specific stains for enolase and S-100 protein clearly demarcated tumor margins after surgical excision. Despite intensive investigation, the histogenesis of this tumor is still in dispute. The most tenable theory at this time is that these tumors are derived either directly from Schwann cells or from undifferentiated cells developing neural characteristics.  相似文献   
25.
Summary The effectiveness of nifedipine retard as a treatment for Raynaud's phenomenon was assessed in 15 patients in a placebo controlled double blind study. An associated connective tissue disease was evident in 7 patients. Changes in finger and forearm blood flow (venous occlusion plethysmography), digital skin temperature and digital systolic pressure were measured acutely before and after a 2-week treatment period. Subjective assessment of efficacy was based on patient diary data. In addition alpha2-adrenoceptor density on platelets was measured before and after chronic nifedipine therapy in both the patient group and in an age-and-sex-matched control group. No significant haemodynamic changes were observed. Nifedipine retard significantly reduced the frequency (p<0.05) with no change in either the duration or severity of vasospastic attacks. Side effects were commono following nifedipine retard. A reduction in alpha2-adrenoceptor density on platelets was observed in patients compared to a control group (p<0.05). Alpha2-adrenoceptor density was unchanged following a 2-week treatment period with nifedipine retard. This study concludes that nifedipine retard is not effective in the treatment of Raynaud's phenomenon over a short time course. Patients with Raynaud's phenomenon have reduced alpha2-adrenoceptor densities on their platelets.  相似文献   
26.
27.
28.
29.
Ossification of the posterior longitudinal ligament (OPLL) is a progressive disorder of the spine which may result in spinal cord compression and myelopathy. While prevalent among Japanese, its occurrence in non-Orientals has been infrequently reported. Nine patients with OPLL have been diagnosed and followed at the Emory Clinic Spine Center over a 5-year period. All of the patients had been misdiagnosed before presentation. Five of the nine had undergone a total of eight ineffective operations. Failure to distinguish OPLL from other more common causes of myelopathy can result in delayed or inappropriate treatment. Illustrative cases and radiographic studies are presented.  相似文献   
30.
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