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   3457469篇
  免费   288010篇
  国内免费   13668篇
耳鼻咽喉   48380篇
儿科学   112009篇
妇产科学   89365篇
基础医学   547391篇
口腔科学   91068篇
临床医学   307862篇
内科学   618076篇
皮肤病学   91277篇
神经病学   294117篇
特种医学   137453篇
外国民族医学   686篇
外科学   536901篇
综合类   102817篇
现状与发展   23篇
一般理论   2274篇
预防医学   289373篇
眼科学   79149篇
药学   238290篇
  23篇
中国医学   9688篇
肿瘤学   162925篇
  2021年   55073篇
  2020年   35087篇
  2019年   58112篇
  2018年   71253篇
  2017年   54268篇
  2016年   59878篇
  2015年   74033篇
  2014年   108206篇
  2013年   173390篇
  2012年   92200篇
  2011年   92170篇
  2010年   116714篇
  2009年   121247篇
  2008年   80002篇
  2007年   83421篇
  2006年   94072篇
  2005年   89600篇
  2004年   91725篇
  2003年   82851篇
  2002年   73020篇
  2001年   110181篇
  2000年   104258篇
  1999年   102992篇
  1998年   66110篇
  1997年   63507篇
  1996年   61458篇
  1995年   56906篇
  1994年   51154篇
  1993年   47690篇
  1992年   72901篇
  1991年   69959篇
  1990年   66462篇
  1989年   64917篇
  1988年   60067篇
  1987年   58892篇
  1986年   55266篇
  1985年   55267篇
  1984年   49881篇
  1983年   45439篇
  1982年   41913篇
  1981年   39679篇
  1980年   37202篇
  1979年   40854篇
  1978年   35753篇
  1977年   32732篇
  1976年   30069篇
  1975年   28981篇
  1974年   29719篇
  1973年   28620篇
  1972年   26566篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
991.
The simultaneous determination of cerebrospinal fluid (CSF) and plasma adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in tuberculous meningitis (TBM). CSF and plasma ADA activity were determined in four groups of patients: (i) a 'no meningitis' group of 174 children investigated for possible meningitis, but found to be uninfected; (ii) an aseptic meningitis group of 40 children; (iii) a bacterial meningitis group of 31 children; and (iv) a TBM group of 27 patients (24 children and 3 adults). CSF ADA alone was determined in a further 23 children with aseptic meningitis, 19 with bacterial meningitis and 13 children and 7 adults with TBM. Both the CSF/plasma ADA ratio and the absolute CSF ADA activity were raised in TBM (mean values 0,24 and 12,61 U/I respectively) and bacterial meningitis (mean values 0,59 and 15,43 U/I respectively), but not in the aseptic meningitis group (mean values 0,06 and 2,00 U/I) or the 'no meningitis' group (mean values 0,04 and 1,51 U/I). Both values will distinguish TBM from aseptic meningitis, but do not appear to hold any marked advantages over conventional CSF criteria in the diagnosis of TBM.  相似文献   
992.
993.
994.
995.
996.
997.
The resolution of three 2-substituted derivatives of idazoxan is described. The enantiomers show large separations in activity in a variety of in vitro and in vivo tests, and the active isomers are all potent and selective antagonists at the alpha 2-adrenoreceptor. The significance of these results in relation to those published on the enantiomers of idazoxan and to those on optically active alpha 2-adrenoreceptor agonists is discussed.  相似文献   
998.
Summary Deaza-aminopterin is a folate analog which is transported more rapidly than methotrexate into cells and appears to be more active than methotrexate against human and animal tumor in vitro. Fifteen patients with advanced urothelial tract cancer were given deaza-aminopterin 30–37.5 mg/m2 IV QW. In responding patients drug was given QOW after 4–6 consecutive doses. Doses were escalated or de-escalated by 7.5 mg/m2 depending on toxicity. Twelve patients had received prior chemotherapy which included methotrexate in nine. Three patients achieved a partial remission lasting 1, 3, and 3 months respectively: all responders had previously failed methotrexate after an initial response to a methotrexate containing regimen. None of the six patients who were methotrexate naive responded to deaza-aminopterin; 3 subsequently received methotrexate without response. Mild mucositis was universal and in 5 was severe. Six patients had an increase in liver transaminases probably secondary to anti-folate hepatotoxicity. Other toxicities included diarrhea, nausea, skin rash and fever. Further studies are needed to define the precise efficacy of deaza-aminopterin in patients with urothelial tract cancers.  相似文献   
999.
A survey of pediatricians in private practice in the Denver and Baltimore metropolitan areas was conducted to assess pediatricians' satisfaction with the telephone in their practices. The response rates were 84% (89/106) in Denver and 72% (90/125) in Baltimore. In both cities, 42% of the physicians were dissatisfied with their telephone systems. Dissatisfied physicians were less likely to provide a morning telephone hour (P less than .02), less likely to delegate calls to office staff (P less than .01), more likely to believe that they lacked sufficient time to handle daytime calls (P less than .0001), and more likely to be in group rather than solo practice (P less than .05). Younger age of the respondent approached, but did not reach, statistical significance in its association with dissatisfaction.  相似文献   
1000.
Summary An infant girl is described who had cor triatriatum and partial anomalous pulmonary venous connection of the left pulmonary veins to the coronary sinus, the first report of this combination of lesions. The infant also had a Dandy-Walker malformation and multiple facial and intrathoracic hemangiomas. The cardiac diagnosis was made by two-dimensional echocardiography. Cardiac catheterization and angiography confirmed the findings and also demonstrated a persistent left superior vena cava draining to the coronary sinus. The infant underwent successful surgical repair. Partial anomalous pulmonary venous connection and left superior vena cava not infrequently are associated with cor triatriatum. Although two-dimensional echocardiography is sensitive for the detection of cor triatriatum, preoperative cardiac catheterization is necessary to identify unequivocally systemic and pulmonary venous connections.  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