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   7523篇
  免费   619篇
  国内免费   7篇
耳鼻咽喉   55篇
儿科学   275篇
妇产科学   292篇
基础医学   961篇
口腔科学   92篇
临床医学   1121篇
内科学   1347篇
皮肤病学   348篇
神经病学   675篇
特种医学   180篇
外科学   627篇
综合类   77篇
一般理论   4篇
预防医学   1109篇
眼科学   42篇
药学   522篇
中国医学   7篇
肿瘤学   415篇
  2023年   55篇
  2022年   61篇
  2021年   140篇
  2020年   89篇
  2019年   140篇
  2018年   163篇
  2017年   134篇
  2016年   156篇
  2015年   175篇
  2014年   234篇
  2013年   367篇
  2012年   503篇
  2011年   540篇
  2010年   245篇
  2009年   219篇
  2008年   460篇
  2007年   461篇
  2006年   483篇
  2005年   483篇
  2004年   462篇
  2003年   422篇
  2002年   391篇
  2001年   101篇
  2000年   99篇
  1999年   118篇
  1998年   88篇
  1997年   77篇
  1996年   76篇
  1995年   69篇
  1994年   52篇
  1993年   47篇
  1992年   77篇
  1991年   64篇
  1990年   71篇
  1989年   65篇
  1988年   44篇
  1987年   63篇
  1986年   48篇
  1985年   36篇
  1984年   46篇
  1983年   36篇
  1982年   42篇
  1981年   48篇
  1980年   39篇
  1979年   46篇
  1978年   45篇
  1976年   31篇
  1975年   25篇
  1974年   25篇
  1973年   28篇
排序方式: 共有8149条查询结果,搜索用时 15 毫秒
1.
2.
3.
Several studies have demonstrated that a descending dopaminergic pathway innervates the dorsal and the intermediate gray matter of the spinal cord and have suggested that this pathway is involved in pain modulation and in the control of autonomie functions. Other studies have also demonstrated the presence of dopamine (DA) and DA metabolites as well as of DA receptors in the ventral cord. There is also evidence for the implication of DA in the control of motor functions at the spinal level. The occurrence of a dopaminergic innervation in the ventral horn has been, however, disputed until recently. But recent work has demonstrated that the motoneural cell groups in the ventral horn (lamina IX) are a target for descending dopaminergic fibers. In addition, the possibility that DA is a mediator of primary afferent fibers has also been postulated. Finally, the occurrence of dopaminergic cell bodies has been suggested in the spinal cord. This indicates that DA is probably implicated in a complex manner in spinal functions. In the present paper the possible involvement of DA in sensory and in motor functions at spinal level will be discussed in view of neurochemical observations made in polyarthritic rats, in which pain-related behavior and reduction of locomotor activity associated with a marked decrease in mobility, are observed.  相似文献   
4.
We studied the incidence of cerebral hemorrhage in an animal model of embolic stroke to determine the safety of aspirin, heparin, and tissue plasminogen activator therapies. We occluded the middle cerebral arteries of rabbits with labeled blood clots and administered either tissue plasminogen activator, heparin, aspirin, tissue plasminogen activator plus aspirin, tissue plasminogen activator plus heparin, or saline at various times after stroke. Compared to saline controls, both the aspirin-only and the tissue plasminogen activator-plus-aspirin groups had a significantly higher incidence of cerebral hemorrhage, whereas the heparin and tissue plasminogen activator combination groups did not. We conclude that aspirin antiplatelet therapy alone may increase the risk of hemorrhagic infarction, whereas heparin or tissue plasminogen activator therapy appears to be relatively safe.  相似文献   
5.
6.
Although there are well-established clinical human milk banks in the United States, there are no milk banks specifically intended to foster research on human milk. The authors' goal was to establish a milk bank with a core data set to support exploratory and hypothesis-driven studies on human milk. Donations to the Cincinnati Children's Research Human Milk Bank are accepted within the context of ongoing, hypothesis-driven research or on an ad hoc basis. Donors must give informed consent, and scientists wishing to use the samples must have Institutional review board approval for their use. Development of more research human milk banks can potentially provide resources for multidisciplinary collaboration and advance the study of human milk and lactation.  相似文献   
7.
8.
9.
10.
Metabolism is one of the major determinants for age-related changes in susceptibility to chemicals. Aldehydes are highly reactive molecules present in the environment that also can be produced during biotransformation of xenobiotics and endogenous metabolism. Although the lung is a major target for aldehyde toxicity, early development of aldehyde dehydrogenases (ALDHs) in lung has been poorly studied. The expression of ALDH in liver and lung across ages (postnatal day 1, 8, 22, and 60) was investigated in Wistar-Han rats. In adult, the majority of hepatic ALDH activity was found in mitochondria, while cytosolic ALDH activity was the highest contributor in lung. Total aldehyde oxidation capability in liver increases with age, but stays constant in lung. These overall developmental profiles of ALDH expression in a tissue appear to be determined by the different composition of ALDH isoforms within the tissue and their independent temporal and tissue-specific development. ALDH2 showed the most notable tissue-specific development. Hepatic ALDH2 was increased with age, while the pulmonary form did not. ALDH1 was at its maximum value at postnatal day 1 (PND1) and decreased thereafter both in liver and lung. ALDH3 increased with age in liver and lung, although ALDH3A1 was only detectible in lung. Collectively, the present study indicates that, in the case of aldehyde exposure, the in vivo responses would be tissue and age dependent.  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