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   21146篇
  免费   2421篇
  国内免费   15篇
耳鼻咽喉   203篇
儿科学   726篇
妇产科学   552篇
基础医学   3181篇
口腔科学   566篇
临床医学   2442篇
内科学   3538篇
皮肤病学   336篇
神经病学   1575篇
特种医学   728篇
外国民族医学   3篇
外科学   2831篇
综合类   430篇
一般理论   27篇
预防医学   2572篇
眼科学   363篇
药学   1750篇
中国医学   92篇
肿瘤学   1667篇
  2021年   223篇
  2020年   176篇
  2019年   253篇
  2018年   364篇
  2017年   217篇
  2016年   251篇
  2015年   309篇
  2014年   425篇
  2013年   609篇
  2012年   903篇
  2011年   938篇
  2010年   518篇
  2009年   485篇
  2008年   826篇
  2007年   887篇
  2006年   951篇
  2005年   923篇
  2004年   874篇
  2003年   846篇
  2002年   836篇
  2001年   812篇
  2000年   821篇
  1999年   730篇
  1998年   297篇
  1997年   256篇
  1996年   279篇
  1995年   257篇
  1994年   230篇
  1993年   204篇
  1992年   580篇
  1991年   497篇
  1990年   497篇
  1989年   441篇
  1988年   429篇
  1987年   431篇
  1986年   419篇
  1985年   383篇
  1984年   305篇
  1983年   245篇
  1982年   194篇
  1981年   180篇
  1980年   168篇
  1979年   281篇
  1978年   212篇
  1977年   174篇
  1976年   159篇
  1975年   167篇
  1974年   197篇
  1973年   190篇
  1972年   194篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Two children with pleomorphic adenomas developing in heterotopic salivary tissue are presented. These are unusual lesions, rarely seen in adults and not previously described in the pediatric age group.  相似文献   
62.
Reports in the literature suggest that the primary sensory neurons of the olfactory system may provide a direct route of entry for agents into the central nervous system (CNS). To investigate whether cadmium, a heavy metal which is normally excluded from the CNS by the blood-brain barrier, can enter the CNS via the olfactory system, rats were exposed either intranasally (unilaterally) or ip to 109Cd (1 mumol Cd labeled with 1 microCi 109Cd). Rats were allowed to survive 7 days, at which point they were euthanized and the kidneys, livers, right and left forebrains, right and left olfactory bulbs, and right and left olfactory epithelia were removed. Tissues were placed in scintillation vials and radioactivity counted. In rats exposed by intranasal instillation, Cd levels were significantly elevated in the kidney, liver and ipsilateral olfactory bulb and epithelium, but not in the contralateral bulb and epithelium or forebrain areas. With the ip exposure, Cd levels were only elevated in the kidney and liver. In a second study the protocol was repeated (without ip exposure), but the olfactory bulbs and epithelium were washed in EDTA before counting. Cd was still present in the bulbs after washing, suggesting that the metal was internal and not bound to the external membrane. In the final experiment, both time course and dose effect of this phenomenon were explored. Rats were exposed either intransally to 1 mumol Cd labeled with 109Cd (1 microCi) and then sacrificed after 1, 3, 7, or 14 days or were exposed to 0.01, 0.1, or 1.0 mumol Cd labeled with 1 microCi 109Cd and sacrificed after 7 days.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
63.
64.
Drug-dependent patients in general hospitals behave in ways that are difficult for medical and surgical staff to manage. Common problems include drug-seeking, states of intoxication and withdrawal, poor compliance, and behavior that is disruptive or dangerous to others. The authors describe an approach to these problematic behaviors based upon early recognition, a clinical perspective, and administrative action. Institutional initiatives are needed to overcome the practical and conceptual obstacles to effective management of these patients.  相似文献   
65.
Galega officinalis L (goatsrue), a plant introduced from Europe and found in abundance in northern Utah, was tested for toxicity in ewes (Ovis aries). Clinical signs of poisoning induced by doses as small as 0.8 g of dried plant/kg body weight/day included dyspnea, anoxia, and foaming nasal discharge. Pathologic signs in animals that died following overdose of the plant included severe hydrothorax, generalized lung congestion, foamy exudate in bronchioles and trachea, epicardial and endocardial petechiation, and pericardial effusion in severely affected ewes. Microscopic lesions included a severe diffuse alveolar and interlobular edema. No significant alterations in blood constituents were observed in treated animals. Ewes administered the plant on several consecutive days developed an apparent adaptation to the toxin of the plant and were thereby able subsequently to tolerate levels 5-10 times the pre-treatment lethal dose with no discernible adverse clinical or pathological effects.  相似文献   
66.
67.
68.
69.
70.
Antenatal administration of glucocorticoids is often used to facilitate fetal lung maturation in cases of prematurity; however, the effects of betamethasone on maternal immune function have not been established. Therefore maternal immune function was assessed with the use of in vitro techniques. Transient and incomplete suppression of the proliferative response to the T-cell mitogen phytohemagglutinin was demonstrated as early as 24 hours after administration of betamethasone. The magnitude and duration of suppression showed a corresponding increase with advancing gestational age, but these effects were not cumulative and were always short-lived (less than 72 hours). No such suppression of the B-cell mitogen lipopolysaccharide was detected. The nonspecific cellular resistance to infection of maternal monocytes was determined through coincubation with the facultative intracellular pathogen Listeria monocytogenes. Increased phagocytic activity with a normal bactericidal effect was measured in the cell preparations obtained from recipients versus nonrecipients of betamethasone. Taken together, these findings clearly show that both specific and nonspecific immune function are intact in the preterm gravid woman after administration of betamethasone and should allay concerns over its use for reasons of infection control alone.  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