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   8160篇
  免费   823篇
  国内免费   10篇
耳鼻咽喉   55篇
儿科学   143篇
妇产科学   161篇
基础医学   1207篇
口腔科学   205篇
临床医学   915篇
内科学   1702篇
皮肤病学   63篇
神经病学   960篇
特种医学   409篇
外科学   972篇
综合类   175篇
一般理论   2篇
预防医学   823篇
眼科学   265篇
药学   514篇
中国医学   7篇
肿瘤学   415篇
  2021年   128篇
  2020年   78篇
  2019年   132篇
  2018年   131篇
  2017年   109篇
  2016年   105篇
  2015年   123篇
  2014年   179篇
  2013年   278篇
  2012年   435篇
  2011年   388篇
  2010年   219篇
  2009年   201篇
  2008年   353篇
  2007年   351篇
  2006年   357篇
  2005年   317篇
  2004年   332篇
  2003年   264篇
  2002年   313篇
  2001年   253篇
  2000年   207篇
  1999年   201篇
  1998年   100篇
  1997年   89篇
  1996年   107篇
  1995年   88篇
  1994年   78篇
  1993年   69篇
  1992年   215篇
  1991年   185篇
  1990年   182篇
  1989年   199篇
  1988年   184篇
  1987年   163篇
  1986年   149篇
  1985年   162篇
  1984年   133篇
  1983年   120篇
  1982年   74篇
  1981年   65篇
  1980年   66篇
  1979年   105篇
  1978年   87篇
  1977年   82篇
  1975年   72篇
  1974年   85篇
  1973年   78篇
  1972年   70篇
  1970年   69篇
排序方式: 共有8993条查询结果,搜索用时 15 毫秒
51.
52.
The effect of a new dihydropyridine slow-channel calcium blocking agent, nisoldipine, on hemodynamics and myocardial blood flow in normal and collateral-dependent areas distal to a chronic coronary artery occlusion were studied in chronically instrumented, conscious dogs. Nisoldipine produced significant and dose-related decreases in arterial blood pressure, an elevation of heart rate and large increases in coronary blood flow velocity. In dogs with an Ameroid constrictor previously implanted to enhance coronary collateral development, this agent produced large increases in perfusion distal to a chronic coronary artery occlusion. In addition, despite a reduction in arterial pressure, nisoldipine preserved renal cortical, intestinal and skeletal muscle blood flow while increasing tissue flow within liver and cerebral cortex. Thus, nisoldipine increases oxygen supply to collateral-dependent myocardium in the presence of reduced driving pressure for collateral perfusion.  相似文献   
53.
54.
55.
A total of 1249 "cold" solitary thyroid nodules were excised at the Brigham and Women's Hospital from 1948 through 1987. Of these nodules, 241 showed malignant conditions: 123 were papillary, 42 were mixed papillary-follicular, and 43 were pure follicular carcinomas. There were also 23 anaplastic, 8 medullary, and 3 Hürthle cell carcinomas. These patients were followed up from 3 to 31 years, with a mean range of 10 years. Fifty-three patients with well-differentiated tumors underwent total thyroidectomies, and 179 underwent subtotal thyroidectomies (excluding anaplastic, medullary, and Hürthle cell tumors). Regional lymph node involvement was commonly found but appeared not to affect survival; tumor size and local spread and extent of thyroid gland involvement did affect survival. A small percentage of well-differentiated thyroid tumors do, in time, undergo anaplastic change that leads to metastasis and death. There was no 30-day mortality rate. The late mortality rate was 2% for papillary and 14% for follicular carcinomas. Papillary tumors are becoming more common. Older aged patients and male patients appear to carry poorer prognoses for survival. The total thyroidectomy procedure has not improved survival over subtotal thyroidectomy and carries a higher complication rate.  相似文献   
56.
M J Fulham  R A Brooks  M Hallett  G Di Chiro 《Neurology》1992,42(12):2267-2273
A unilateral supratentorial lesion may cause hypometabolism in the contralateral cerebellar hemisphere (crossed cerebellar diaschisis). We analyzed glucose metabolism, measured by PET-FDG, in the posterior fossa in 67 patients (78 PET studies) with primary unilateral supratentorial brain tumors selected for visually obvious metabolic asymmetry in the cerebellar hemispheres. We found that glucose utilization was 17% lower in the contralateral cerebellar cortex (compared with the ipsilateral one), consistent with the selection criterion, and 19% lower in the ipsilateral pons, wherein lie the first order synapses of the corticopontocerebellar pathway. This finding helps to validate the prevalent view that cerebellar diaschisis is due to interruption of afferent input from the corticopontocerebellar pathway. However, glucose metabolism in the contralateral dentate nucleus was relatively preserved--only 2% less than the ipsilateral dentate. This "dentate sparing" suggests preservation of afferent input to the largest of the deep cerebellar nuclei from the Purkinje cells in the cortex, despite interruption of the major excitatory input to the Purkinje cells.  相似文献   
57.
58.
59.
The major causative agents of bacterial meningitis, Haemophilus influenzae serogroup B, Neisseria meningitidis serogroups B and C, Klebsiella pneumoniae, Streptococcus pneumoniae, and two types of Escherichia coli, were cultured in a modified chemically defined Catlin medium and in a commercial version of the unmodified Catlin medium. The spent media were extracted under acidic conditions, and electron-capturing derivatives were prepared by derivatization with trichloroethanol or haptafluorobutyric anhydride. The derivatives were analyzed on a gas chromatograph equipped with a frequency-pulsed electron capture detector and a PEP-2 computer. The data obtained from the study show that these organisms can be easily distinguished from each other on the basis of metabolic products detected in either type of medium. Three different metabolic groups were detected within two serogroups of N. meningitidis. The methods are practical, and the new technique should offer clinical laboratories and hospitals a better method for rapid identification of this important group of pathogens.  相似文献   
60.
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