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   1528048篇
  免费   94579篇
  国内免费   1826篇
耳鼻咽喉   20948篇
儿科学   48637篇
妇产科学   39528篇
基础医学   232494篇
口腔科学   40309篇
临床医学   137057篇
内科学   284524篇
皮肤病学   34335篇
神经病学   110401篇
特种医学   59974篇
外国民族医学   254篇
外科学   230198篇
综合类   28019篇
现状与发展   3篇
一般理论   360篇
预防医学   108219篇
眼科学   34960篇
药学   121096篇
  8篇
中国医学   3682篇
肿瘤学   89447篇
  2018年   16055篇
  2017年   12335篇
  2016年   14101篇
  2015年   15669篇
  2014年   21231篇
  2013年   31100篇
  2012年   43794篇
  2011年   46978篇
  2010年   27434篇
  2009年   25378篇
  2008年   43335篇
  2007年   47000篇
  2006年   47131篇
  2005年   44931篇
  2004年   43287篇
  2003年   41649篇
  2002年   40184篇
  2001年   78213篇
  2000年   80136篇
  1999年   66465篇
  1998年   16870篇
  1997年   14672篇
  1996年   14681篇
  1995年   13749篇
  1994年   12417篇
  1993年   11919篇
  1992年   49821篇
  1991年   49461篇
  1990年   49089篇
  1989年   47476篇
  1988年   43024篇
  1987年   42066篇
  1986年   39377篇
  1985年   37277篇
  1984年   27177篇
  1983年   23039篇
  1982年   12401篇
  1979年   24811篇
  1978年   16947篇
  1977年   14710篇
  1976年   13611篇
  1975年   15878篇
  1974年   18202篇
  1973年   17621篇
  1972年   16630篇
  1971年   15752篇
  1970年   14565篇
  1969年   13894篇
  1968年   12577篇
  1967年   11281篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Cutaneous plasmacytosis is a rare disorder characterized by a benign proliferation of mature plasma cells that appears as multiple dark-brown to purplish skin lesions, often associated with polyclonal hypergammaglobulinaemia. We present the case of a 55-year-old Caucasian man who suffered from a cutaneous plasmacytosis associated with two different carcinomas. Cutaneous plasmacytosis seems to be a reactive process because most cases reported are not associated with any apparent underlying disease. Nevertheless, because few reported cases were associated with malignancies, screening of additional neoplasms would be justified.  相似文献   
52.
53.
The absence of the temporary incisors could be to a genetic illness or to some multiple premature extractions. These extractions are the aftermaths of the carious lesions or some traumatisms underwent by the temporary incisors. Beyond measure the loss of the space, the premature loss some temporary incisors very often assign the relational development of the child and disturb its psychological development and the aesthetic function. Across some cases clinics, the authors show that the replacement of the temporary incisors is the therapeutic ideal solution. Indeed, the child prosthesis, replacing the temporary absent incisors, solves the psychological, aesthetic and relational problems of the child.  相似文献   
54.
55.
Published data devoted to making and characterization of the properties of polymeric wound dressings with proteolytic action are reviewed. These data are indicative of individual dependence of the physicochemical properties, activity, and stability of each particular enzyme on the type of polymer matrix and the method of immobilization. In order to obtain wound dressings, which are active in physiological medium and retain their activity upon sterilization, it is necessary to optimize the composition and characteristics of a polymer matrix and the enzyme included into its structure. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 8, pp. 24–28, August, 2006.  相似文献   
56.
A Survey of Plants Used as Wild Vegetables in Four Districts of Botswana   总被引:1,自引:0,他引:1  
A survey of plants used as wild vegetables was conducted in four districts of Botswana in August and September 2005. The objective was to determine which wild plants were used as vegetables in the study area, and to document their cooking and preservation methods. Fourteen species representing seven families were mentioned as wild vegetables. In addition, six species from four families had other uses in traditional medicine. The implications of the documented processing methods on the retention of nutrients in the vegetables are discussed.  相似文献   
57.
58.
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   
59.
The aim of this study was to determine whether patients with sickle cell disease (SCD) in steady state had pulmonary abnormalities seen on high-resolution computed tomography (HRCT) and whether any abnormalities correlated with contemporaneously diagnosed lung function abnormalities. A subsidiary question was whether the results of a noninvasive measure of haemolysis (end-tidal carbon monoxide (ETCO) levels) correlated with pulmonary function abnormalities. Thirty three patients with SCD, median (range) age 36 yrs (17-67 yrs) were examined. The degree of lobar volume loss and ground-glass opacification and prominence of central vessels on HRCT were quantitatively assessed. Pulmonary function was assessed by measurements of lung volumes, spirometry, gas transfer and oxygen saturation. ETCO levels were measured using an end-tidal CO monitor. Forced expiratory volume in one second (FEV1), forced vital capacity and total lung capacity significantly correlated with HRCT findings, particularly lobar volume loss. ETCO levels significantly negatively correlated with FEV1, vital capacity measured using a plethysmograph, specific airway conductance and arterial oxygen saturation measured by pulse oxymetry. In conclusion, the present results suggest that high-resolution computed tomography noninvasive assessment of haemolysis might be useful to identify sickle cell disease patients with respiratory function impairment.  相似文献   
60.
Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients' view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.  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