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   1340872篇
  免费   94333篇
  国内免费   2914篇
耳鼻咽喉   19791篇
儿科学   40451篇
妇产科学   38779篇
基础医学   187987篇
口腔科学   39897篇
临床医学   113077篇
内科学   263246篇
皮肤病学   30374篇
神经病学   106830篇
特种医学   53848篇
外国民族医学   435篇
外科学   208928篇
综合类   31069篇
现状与发展   6篇
一般理论   436篇
预防医学   92342篇
眼科学   31463篇
药学   100272篇
  4篇
中国医学   2989篇
肿瘤学   75895篇
  2018年   11868篇
  2015年   11934篇
  2014年   16880篇
  2013年   25650篇
  2012年   33234篇
  2011年   35093篇
  2010年   21014篇
  2009年   20576篇
  2008年   33752篇
  2007年   36842篇
  2006年   37413篇
  2005年   36134篇
  2004年   35232篇
  2003年   34156篇
  2002年   33680篇
  2001年   63722篇
  2000年   65442篇
  1999年   55506篇
  1998年   14766篇
  1997年   13587篇
  1996年   13038篇
  1995年   12316篇
  1994年   11555篇
  1992年   42820篇
  1991年   41327篇
  1990年   40605篇
  1989年   39611篇
  1988年   37011篇
  1987年   36464篇
  1986年   34935篇
  1985年   33144篇
  1984年   24867篇
  1983年   21094篇
  1982年   12715篇
  1981年   11605篇
  1980年   10798篇
  1979年   23954篇
  1978年   17101篇
  1977年   14864篇
  1976年   13410篇
  1975年   15282篇
  1974年   18102篇
  1973年   17580篇
  1972年   16825篇
  1971年   15735篇
  1970年   14930篇
  1969年   14357篇
  1968年   13465篇
  1967年   12027篇
  1966年   11274篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
51.
52.
53.
In chronic myeloid leukaemia, CD34(+) stem/progenitor cells appear resistant to imatinib mesylate (IM) in vitro and in vivo. To investigate the underlying mechanism(s) of IM resistance, it is essential to quantify Bcr-Abl kinase status at the stem cell level. We developed a flow cytometry method to measure CrkL phosphorylation (P-CrkL) in samples with <10(4) cells. The method was first validated in wild-type (K562) and mutant (BAF3) BCR-ABL(+) as well as BCR-ABL(-) (HL60) cell lines. In response to increasing IM concentration, there was a linear reduction in P-CrkL, which was Bcr-Abl specific and correlated with known resistance. The results were comparable to those from Western blotting. The method also proved to be reproducible with small samples of normal and Ph(+) CD34(+) cells and was able to discriminate between Ph(-), sensitive and resistant Ph(+) cells. This assay should now enable investigators to unravel the mechanism(s) of IM resistance in stem cells.  相似文献   
54.
There is increasing evidence that the assessment of eosinophilic airway inflammation using induced sputum and measurement of airway hyperresponsiveness provides additional, clinically important information concerning asthma control. The aim of this study was to directly compare the effects of different treatments on these markers in patients with asthma and persistent symptoms, despite the use of low-dose inhaled corticosteroids. A double-blind four-way crossover study was performed, which compared a 1-month treatment with budesonide 400 mug b.i.d., additional formoterol, additional montelukast and placebo in 49 patients with uncontrolled asthma despite budesonide 100 mug b.i.d., with each treatment separated by a 4-week washout period. The change in sputum eosinophil count with formoterol (2.4 to 3.8% change, 0.6-fold reduction, 95% confidence interval (CI) 0.5-0.9) differed significantly from placebo (2.8 to 2.5% change, 1.1-fold reduction, 95% CI 0.7-1.6) and high-dose budesonide (2.7 to 1.6% change, 1.6-fold reduction, 95% CI 1.2-2.2). The effects of montelukast did not differ from placebo. The changes in methacholine airway responsiveness were small and did not differ between treatments. High-dose budesonide had the broadest range of beneficial effects on other outcomes, including symptom scores, morning peak expiratory flow and forced expiratory volume in one second. In conclusion, treatment given in addition to low-dose inhaled corticosteroids results in modest benefits. Formoterol and high-dose budesonide have contrasting effects on eosinophilic airway inflammation.  相似文献   
55.
56.
Severe adverse effects during the use of ovulation inhibitors occur mostly in women who have an elevated risk for the development of certain diseases owing to hereditary or acquired factors. By means of a careful personal or family history analysis as well as specific laboratory examinations, an existing predisposition may frequently be diagnosed and the individual risk associated with the use of oral contraceptive inhibitors may be estimated. The present contribution describes the potential effects of treatment with ovulation inhibitors on women with thrombophilia, cardiovascular disease, diabetes mellitus, dyslipidemia, overweight or underweight, tumors, psychiatric and neurological diseases and autoimmune disease. The hormonal methods and non-hormonal alternatives available for contraception are elucidated according to existing lesions and risk factors and the advantages and disadvantages are discussed.  相似文献   
57.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  相似文献   
58.
59.
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