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   705793篇
  免费   48885篇
  国内免费   1312篇
耳鼻咽喉   9168篇
儿科学   23267篇
妇产科学   17603篇
基础医学   110394篇
口腔科学   19955篇
临床医学   63752篇
内科学   134313篇
皮肤病学   16162篇
神经病学   49431篇
特种医学   25737篇
外国民族医学   76篇
外科学   104467篇
综合类   14818篇
现状与发展   2篇
一般理论   160篇
预防医学   51386篇
眼科学   16318篇
药学   53943篇
  3篇
中国医学   2359篇
肿瘤学   42676篇
  2021年   5431篇
  2018年   7859篇
  2017年   6105篇
  2016年   6818篇
  2015年   7548篇
  2014年   10262篇
  2013年   15376篇
  2012年   20498篇
  2011年   21480篇
  2010年   12715篇
  2009年   11939篇
  2008年   19993篇
  2007年   21507篇
  2006年   21901篇
  2005年   20436篇
  2004年   19986篇
  2003年   18938篇
  2002年   18453篇
  2001年   36329篇
  2000年   36896篇
  1999年   30378篇
  1998年   7875篇
  1997年   6663篇
  1996年   6970篇
  1995年   6627篇
  1994年   6096篇
  1993年   5590篇
  1992年   22967篇
  1991年   22925篇
  1990年   22309篇
  1989年   22076篇
  1988年   20035篇
  1987年   19417篇
  1986年   18467篇
  1985年   17305篇
  1984年   12697篇
  1983年   10741篇
  1982年   5921篇
  1979年   11518篇
  1978年   8128篇
  1977年   6832篇
  1976年   6594篇
  1975年   7268篇
  1974年   8498篇
  1973年   8141篇
  1972年   7658篇
  1971年   7127篇
  1970年   6877篇
  1969年   6306篇
  1968年   5780篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Positron emission tomography was performed on six patients with Rett syndrome to investigate cerebral blood flow and oxygen metabolism, and the results were compared with the concurrent clinical status of the patients. The cerebral metabolic rate of oxygen (CMRO2) was low in five patients, and oxygen extraction fraction was low in four patients; both had a tendency to decline with advancing age. Although the cause is unknown, it is suggested that impaired oxidative metabolism exists in Rett syndrome. An analysis of the distribution among brain regions showed that the ratios of values for the frontal cortex to those for the temporal cortex for both cerebral blood flow and CMRO2 were lower than those for the controls, which may indicate the loss of hyperfrontality in Rett syndrome.  相似文献   
972.
973.
974.
975.
4-(1H-Benzimidazol-1-ylmethyl)-and 4-(2-methyl-1H-benzimidazol-1-ylmethyl)phenyl-β-D-glucopyranosides have been synthesized by glycosylation of the corresponding phenols. The hemolytic activity of the synthesized compounds was studied on whole venous human donor blood at concentrations of 100, 200, and 300 μg/mL. It was established that the glycosides exhibit high biological activity and enter erythrocytes faster than do the initial phenols, which suggests that they are promising for the development of new drugs. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 12, pp. 16–17, December, 2007.  相似文献   
976.
977.
The gamma-irradiation of adult rats with a semi-lethal dose (6 Gy) suppressed the posttraumatic regeneration of skeletal muscles and brought about considerable destructive changes in the thymus. The effect of He-Ne laser radiation at a total dose 4.5-5.4 J/cm2 at each operated leg in irradiated rats stimulated the regenerative capacity of skeletal muscle tissue, the healing of skin-muscle wound, and the processes of postradiation recovery in thymus cells (a decrease of chromosome aberrations). The histological structure of regenerates had more muscle pattern. At the same time, the positive dynamics of regenerative processes in muscles was achieved by an increased functional load on the thymus. To stimulate the regeneration of irradiated muscles on the background of a more moderate load on the thymus, the prolonged period of laser therapy and fragmentary distribution of laser exposures during muscle regeneration were preferable. Wound healing improved visibly. Nor formation of chronic radiation ulcers on operated shins was observed.  相似文献   
978.
979.
A case of radiologically occult lung cancer is presented in which 201TI SPECT of the chest clearly delineated the involved area. A 66-yr-old man underwent chest screening examinations for asymptomatic smokers and presented a positive sputum cytology for lung cancer. Conventional chest x-ray, tomography of computed radiography, and a CT scan failed to locate the lesion in the lung. Thallium-201 SPECT, however, was successful in depicting the area of the involvement.  相似文献   
980.
Neuroprotective activity with magnesium associated with animal models of cerebral ischaemia, seizure, perinatal hypoxia/ischaemia, subarachnoid haemorrhage and traumatic brain injury has provided the justification for clinical stroke trials. However, the recent IMAGES stroke clinical trial found magnesium to be largely ineffective. Hence, due to the negative stroke trial outcome, current FAST-MAG trial and our own experience with magnesium in cerebral ischaemia animal models, we thought it prudent to review these preclinical and clinical studies. We reviewed nine studies describing the use of magnesium following global cerebral ischaemia and fourteen following focal cerebral ischaemia. Four global ischaemia and six focal ischaemia studies did not show a significant neuroprotective effect with magnesium. In the majority of positive magnesium studies animal body temperature was not monitored post-ischaemia. Thus the effects of post-ischaemic hypothermia cannot be ruled out as a confounding factor in positive magnesium cerebral ischaemia studies. Moreover, data from our own laboratory indicates that magnesium is only neuroprotective when combined with post-ischaemic hypothermia. These data provide a possible explanation of why the IMAGES trial was largely unsuccessful, as current stroke patient management does not involve hypothermia induction. Future preclinical and clinical cerebral ischaemia trials with magnesium should consider combining treatment with mild hypothermia.  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