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   1140459篇
  免费   72985篇
  国内免费   1768篇
耳鼻咽喉   14802篇
儿科学   37410篇
妇产科学   28760篇
基础医学   181713篇
口腔科学   30520篇
临床医学   102572篇
内科学   215090篇
皮肤病学   25738篇
神经病学   79429篇
特种医学   42222篇
外国民族医学   126篇
外科学   169567篇
综合类   21626篇
现状与发展   3篇
一般理论   251篇
预防医学   83229篇
眼科学   26410篇
药学   86689篇
  4篇
中国医学   3244篇
肿瘤学   65807篇
  2021年   8657篇
  2018年   12562篇
  2017年   9481篇
  2016年   10731篇
  2015年   11987篇
  2014年   16216篇
  2013年   24320篇
  2012年   33551篇
  2011年   35972篇
  2010年   21028篇
  2009年   19473篇
  2008年   33157篇
  2007年   36010篇
  2006年   35920篇
  2005年   33931篇
  2004年   33034篇
  2003年   31633篇
  2002年   30695篇
  2001年   54892篇
  2000年   55784篇
  1999年   46147篇
  1998年   12255篇
  1997年   10360篇
  1996年   10650篇
  1995年   10031篇
  1994年   9172篇
  1992年   34737篇
  1991年   35351篇
  1990年   34688篇
  1989年   34324篇
  1988年   31286篇
  1987年   30662篇
  1986年   28901篇
  1985年   27372篇
  1984年   20213篇
  1983年   17182篇
  1982年   9365篇
  1979年   18806篇
  1978年   13255篇
  1977年   10941篇
  1976年   10946篇
  1975年   12542篇
  1974年   14479篇
  1973年   13940篇
  1972年   13009篇
  1971年   12307篇
  1970年   11765篇
  1969年   10880篇
  1968年   10123篇
  1967年   9022篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
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   
52.
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   
53.
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   
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.
57.
58.
59.
Abstract The pain of cluster headache attacks is severe, excruciating and selectively responsive to subcutaneous sumatriptan. Serious cardiovascular events attributed to sumatriptan are extremely rare and have most often been reported in patients at significant cardiovascular risk, or in overt cardiovascular disease. They also have occurred, however, in patients without evidence of cardiovascular disease. We describe a 42-year-old man with episodic cluster headache without history of coronary artery disease who was admitted to our coronary care unit for acute myocardial infarction after 3 h of subcutaneous injection of sumatriptan. During hospitalisation cluster headache attacks were successfully treated with e.v. indomethacin.  相似文献   
60.
BACKGROUND: The incidence of malignant melanoma of the skin has risen in every part of the world where reliable cancer registration data are found. OBJECTIVE: Our study aims to describe the changing incidence of and survival from invasive cutaneous malignant melanoma in Malta, by analysing the data from the 211 cases that were registered at the Malta National Cancer Registry between 1993 and 2002. RESULTS: The age standardized incidence rates for invasive cutaneous malignant melanoma rose from 3.7 per 100,000 population per year for males and 5.1 for females in the first 5-year period, to 8.0 per 100,000 population per year for males and 5.9 for females in the second 5-year period. In both sexes, numbers of thin (< or = 1.0 mm) invasive melanomas increased significantly between 1993 and 2002; males also registered a significant increase in intermediate-thickness (1.01-4.0 mm) melanomas. The increase in numbers of thin and intermediate-thickness melanomas between the two 5-year periods was greatest in patients aged 60 years and over. The overall absolute 5-year survival rate for the first period was 74% and for the second period 92%. CONCLUSION: Numbers of reported cases of invasive cutaneous malignant melanoma in Malta have more than doubled during the 10-year study period. This is mostly due to a marked rise in the diagnosis of thin melanomas in both sexes, occurring mainly in patients aged 60 years and over. As thin melanomas are of low metastasizing potential, this has resulted in an increase in survival between the two 5-year study periods.  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