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   681篇
  免费   54篇
  国内免费   19篇
耳鼻咽喉   1篇
儿科学   30篇
妇产科学   5篇
基础医学   60篇
口腔科学   28篇
临床医学   90篇
内科学   118篇
皮肤病学   6篇
神经病学   10篇
特种医学   108篇
外科学   22篇
综合类   10篇
预防医学   37篇
眼科学   2篇
药学   175篇
中国医学   2篇
肿瘤学   50篇
  2022年   2篇
  2019年   12篇
  2018年   8篇
  2017年   6篇
  2016年   9篇
  2015年   11篇
  2014年   8篇
  2013年   23篇
  2012年   6篇
  2011年   10篇
  2010年   28篇
  2009年   28篇
  2008年   13篇
  2007年   26篇
  2006年   22篇
  2005年   28篇
  2004年   30篇
  2003年   16篇
  2002年   23篇
  2001年   17篇
  2000年   15篇
  1999年   16篇
  1998年   32篇
  1997年   33篇
  1996年   29篇
  1995年   26篇
  1994年   26篇
  1993年   21篇
  1992年   6篇
  1991年   15篇
  1990年   10篇
  1989年   21篇
  1988年   25篇
  1987年   16篇
  1986年   22篇
  1985年   19篇
  1984年   13篇
  1983年   8篇
  1982年   16篇
  1981年   11篇
  1980年   8篇
  1979年   5篇
  1978年   4篇
  1977年   5篇
  1976年   3篇
  1975年   8篇
  1974年   4篇
  1971年   2篇
  1970年   3篇
  1968年   2篇
排序方式: 共有754条查询结果,搜索用时 0 毫秒
91.
92.
93.
Summary The haemodynamic effects of an i.v. infusion of 2 mg nitrendipine have been studied in six healthy volunteers.Nitrendipine significantly decreased the systolic (–8.3%) diastolic (–19.9%) and mean arterial (–11.6%) blood pressures and the peripheral vascular resistance (–57.8%), and significantly increased leg blood flow (+128%).Stroke volume did not change. Due to the increase in heart rate (+28.5%), the cardiac output (2.8.2%) rose significantly. The haemodynamic effects were closely related to the serum nitrendipine concentration. The sigmoidal Emax-model was appropriate to describe the data.Pronounced interindividual differences in the serum nitrendipine concentrations required to elicit 50% of the maximum haemodynamic effect (EC50) were observed. The EC50 for the increase in leg blood flow ranged from 2.9 to 30.9 ng/ml and for the reduction in peripheral vascular resistance from 2.1 to 25.7 ng/ml. Interindividual differences in EC50 values were less pronounced if based on unbound serum nitrendipine levels.The fraction of nitrendipine not bound to serum proteins showed a three-fold difference between subjects, with free fractions ranging from 0.011 to 0.036. The unbound EC50 values for the increase in leg blood flow varied between 0.06 and 0.44 ng/ml and for the reduction in peripheral vascular resistance from 0.07 to 0.35 ng/ml.Based on the serum concentrations associated with comparable haemodynamic effects nitrendipine was at least three-times more potent than nifedipine.  相似文献   
94.
Malignant uveal melanoma and simulating lesions: MR imaging evaluation   总被引:7,自引:0,他引:7  
Twenty-one patients with intraocular disease were studied by magnetic resonance (MR) imaging and computed tomography (CT). In 13 cases, malignant uveal melanoma was considered the likely diagnosis. Both imaging methods were accurate in determining the location and size of uveal melanomas. MR imaging was superior for the assessment of possible associated retinal detachment, for assessment of vitreous change, and for differentiating uveal melanoma from choroidal hemangioma and choroidal detachment. A case of retinal gliosis could not be differentiated from uveal melanoma by either technique. Uveal melanomas appeared as hyperintense lesions on T1-weighted images and as hypointense lesions on T2-weighted images. High signal intensity of the vitreous was observed in patients with vitritis and in those who were thought to have protein leaking into the vitreous as a result of impairment of the retinal-blood barrier.  相似文献   
95.
OBJECTIVE: To evaluate the accuracy of a rapid assay that wasdeveloped to detect Helicobacter pylori antigen in the stool,using the principle of immunochromatography, in the Chinese population. METHODS: Eligible patients without prior treatment of H.pylori were recruited. An in‐house rapid urease test (RUT) andhistology were used as the gold standard. The results of the rapidstool antigen test were compared with the gold standard. RESULTS: Valid rapid stool antigen test results for interpretationwere obtained from 94 consecutive patients (mean age: 52.5, range:22?82 years). Sensitivity, specificity, positive predictivevalue, negative predictive value and accuracy were, respectively, 77.5%,87.0%, 81.6%, 83.9% and 83.0%.The test was easy to perform and results were available within 15 min. CONCLUSION: The rapid stool antigen test using immunochromatography accuratelydiagnoses H. pylori infection in Chinese patients.  相似文献   
96.
97.
98.
99.
A gene cloning strategy based on the screening of the Expressed Sequence Tags database (dbEST) using sequences of mitochondrial housekeeping proteins of yeast was employed to identify the cDNA encoding the precursor of the human mitochondrial RNA polymerase (h- mtRPOL). The 3831 bp h-mtRPOL cDNA is located on chromosome 19p13.3 and encodes a protein of 1230 amino acid residues. The protein sequence shows significant homologies with sequences corresponding to mitochondrial RNA polymerases from lower eukaryotes, and to RNA polymerases from several bacteriophages. The mitochondrial RNA polymerase carries out the central activity of mitochondrial gene expression and, by providing the RNA primers for replication- initiation, is also implicated in the maintenance and propagation of the mitochondrial genome. Genes involved in the control of mtDNA replication and gene expression are attractive candidates for human disorders due to abnormalities of nucleo-mitochondrial intergenomic signalling. The availability of the h-mtRPOL cDNA will allow us to test its role in mitochondrial pathology. In addition, we propose the 'cyberscreening' of dbEST, based on yeast/human cross-species comparison, as a powerful, simple, rapid and inexpensive method, that may accelerate several-fold the molecular dissection of the human mitochondrial proteome.   相似文献   
100.
We report a patient with Churg-Strauss syndrome (CSS) with asthma, eosinophilia, nasal polyposis and ANCA-associated multisystem vasculitis, who's skin eruption started with erythematous urticarial-plaques followed by haemorrhagic bullae. Histology of the plaques revealed 'flame figures' in the dermis with no granulomatous or vasculitic process, consistent with the diagnosis of eosinophilic cellulitis or Wells' syndrome. The association of CSS and Wells' syndrome observed in this patient may have a common pathogenesis. CSS may induce Wells' syndrome by an unknown factor.  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