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   4023753篇
  免费   284371篇
  国内免费   9071篇
耳鼻咽喉   55889篇
儿科学   131777篇
妇产科学   110654篇
基础医学   573871篇
口腔科学   112085篇
临床医学   370586篇
内科学   776191篇
皮肤病学   92946篇
神经病学   326008篇
特种医学   152264篇
外国民族医学   1141篇
外科学   600932篇
综合类   83701篇
现状与发展   15篇
一般理论   1603篇
预防医学   315083篇
眼科学   93706篇
药学   296409篇
  16篇
中国医学   7858篇
肿瘤学   214460篇
  2019年   32319篇
  2018年   44694篇
  2017年   33875篇
  2016年   38959篇
  2015年   43848篇
  2014年   61257篇
  2013年   92787篇
  2012年   125047篇
  2011年   132763篇
  2010年   79844篇
  2009年   75925篇
  2008年   124274篇
  2007年   132126篇
  2006年   134028篇
  2005年   129330篇
  2004年   124439篇
  2003年   119945篇
  2002年   116010篇
  2001年   183197篇
  2000年   188050篇
  1999年   158990篇
  1998年   47224篇
  1997年   41505篇
  1996年   41659篇
  1995年   40045篇
  1994年   36774篇
  1993年   34603篇
  1992年   124698篇
  1991年   120863篇
  1990年   117553篇
  1989年   113939篇
  1988年   104877篇
  1987年   102763篇
  1986年   96745篇
  1985年   92737篇
  1984年   69329篇
  1983年   59039篇
  1982年   35198篇
  1981年   31696篇
  1979年   62923篇
  1978年   44742篇
  1977年   37780篇
  1976年   35567篇
  1975年   37980篇
  1974年   45306篇
  1973年   43166篇
  1972年   40616篇
  1971年   38158篇
  1970年   35138篇
  1969年   33822篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We describe a mild form of drug-induced pemphigus in a woman with essential arterial hypertension treated with captopril. Complete recovery was observed three weeks after the therapy had been discontinued.  相似文献   
992.
993.
Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from orgnas of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gaschro-matography/massspectrometry (GC/ MS). DNA adducts, 7-methylguanine (7-MeG) and O6-Methylguanine(08-MeG), incorporation of14C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA add,ue,ts in the studied organs was only quantitatively different. The formation of O6-MeG was further pioved by analysing the acidic hydrolysates using HPLC with non-radioactive O6MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis.  相似文献   
994.
Summary A randomised crossover study was performed in subjects with rheumatoid arthritis (or other arthropathies) to investigate if any alteration in the steady pharmacokinetics of the NSAID piroxicam (a drug which is extensively metabolised via cytochrome P450) or its major metabolites occurred as a result of coadministering either cimetidine or nizatidine.Twelve females and 2 males with mean age, weight, and albumin concentrations of 58 years, 61 kg, and 40 g·L–1 respectively, completed the study. Comparisons were made between the following parameters: plasma piroxicam AUCs [AUC0-24(P)], plasma 5-hydroxypiroxicam AUCs [AUC0-24(5-OHP)], the ratio of these i.e. AUC0-24(5-OHP):AUC0-24(p), the % piroxicam daily dose excreted in urine as 5-hydroxypiroxicam (before and after glucuronidase incubation); and the mean of the steady state trough piroxicam, and 5-hydroxypiroxicam concentrations (obtained during each study phase in addition to the wash-out period).A statistically significant difference as a result of initiating either cimetidine or nizatidine was obtained only for the ratio AUC0-23(5-OHP):AUC0-24(P). This was indicative of a weak potential to inhibit piroxicam hydroxylation.No clinically significant alteration in the steady state pharmacokinetics of piroxicam occurred in these subjects as a result of cimetidine or nizatidine coadministration. Consequently it is unlikely that any adverse events would arise from these combinations.  相似文献   
995.
996.
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic.  相似文献   
997.
998.
. Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques. Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral blood neutrophil. Received August 17, 1995; received in revised form and accepted November 27, 1995  相似文献   
999.
We have previously reported the presence of activated (HLA-DR+) T cells in multiple myeloma (MM) patients. These cells produce high amounts of interleukin (IL)-2 and interferon (IFN)-gamma and generate a potent antiplasma cell activity after appropriate in vitro stimulation, but they are unable in vivo to hold in check the disease. Activated T cells are highly susceptible to apoptosis, a form of programmed cell death involved in the modulation of immune responses and regulated by molecules such as Fas (CD95) and bcl-2. The aim of this study was to determine the expression of Fas and bcl-2 antigens and the susceptibility to apoptosis in T cells of MM patients. Fas+ cells were significantly higher, whereas bcl-2+ cells were significantly lower in MM patients than in the controls. MM patients with the highest number of HLA-DR+ T cells showed the highest Fas and the lowest bcl-2 expression. Two-color cytofluorometric analysis confirmed in individual cells that HLA-DR+ T cells coexpressed Fas and lacked bcl-2. Susceptibility to apoptosis was then investigated to evaluate the consequence of dysregulated Fas and bcl-2 expression. The percentage of apoptotic cells after incubation in medium alone (spontaneous apoptosis) or in the presence of methylprednisolone (MP) or anti-Fas monoclonal antibody (triggered apoptosis) was significantly higher in MM and mainly restricted to HLA-DR+ T cells. Spontaneous apoptotosis was reverted by exogenous IL-2. In conclusion, MM T cells have a dysregulated expression of Fas and bcl-2 antigens that is associated with an enhanced susceptibility to apoptosis. These data may unravel a novel mechanism by which activated MM T cells are weakened in their ability to exert an effective antitumor activity in vivo.  相似文献   
1000.
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