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   14500篇
  免费   1200篇
  国内免费   94篇
耳鼻咽喉   118篇
儿科学   551篇
妇产科学   338篇
基础医学   1800篇
口腔科学   236篇
临床医学   1676篇
内科学   2894篇
皮肤病学   439篇
神经病学   1349篇
特种医学   597篇
外科学   1840篇
综合类   372篇
一般理论   7篇
预防医学   1221篇
眼科学   256篇
药学   828篇
中国医学   4篇
肿瘤学   1268篇
  2021年   170篇
  2019年   182篇
  2018年   212篇
  2017年   163篇
  2016年   184篇
  2015年   191篇
  2014年   278篇
  2013年   431篇
  2012年   567篇
  2011年   640篇
  2010年   335篇
  2009年   375篇
  2008年   595篇
  2007年   612篇
  2006年   573篇
  2005年   620篇
  2004年   542篇
  2003年   513篇
  2002年   509篇
  2001年   491篇
  2000年   521篇
  1999年   436篇
  1998年   205篇
  1997年   190篇
  1996年   142篇
  1995年   157篇
  1994年   132篇
  1993年   111篇
  1992年   364篇
  1991年   356篇
  1990年   374篇
  1989年   373篇
  1988年   286篇
  1987年   312篇
  1986年   312篇
  1985年   314篇
  1984年   210篇
  1983年   237篇
  1982年   140篇
  1980年   111篇
  1979年   203篇
  1978年   147篇
  1977年   135篇
  1976年   145篇
  1975年   135篇
  1974年   144篇
  1973年   136篇
  1972年   107篇
  1970年   119篇
  1969年   104篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
21.
Desferrioxamine (DFO) metabolism and its pharmacokinetics were studied in a swine model using high-performance liquid chromatography. DFO and three iron-binding metabolites occurred in plasma. Interindividual differences in pharmacokinetics and metabolism were observed. Urine analysis in 4 pigs showed three iron-binding metabolites. The mean percent dose excreted in urine in the form of the parent drug was 45 +/- 10% and 10 +/- 2% (means +/- SD) in the form of metabolites. Of the total amount of the parent drug infused, 3 h after initiation, 87% was in the form of DFO, whereas 13% was present as the DFO-iron III complex which represented 45 mg of urinary iron elimination. The described DFO infusion protocol provides for sufficient DFO to chelate significant amounts of ferric iron in excess of normal levels, thus allowing experimental studies of iron chelation in a variety of disease states.  相似文献   
22.
The qualities of daughter versus same-sex friend relationships were described by 151 married and widowed elderly women. The relation of these qualities to life satisfaction was assessed. Relationship qualities predicted life satisfaction in widowed women but not in married women. Significant predictors of life satisfaction for widows included the emotional support of daughters, the instrumental support of friends and friendship strength. In a comparison of the relationship qualities, both married and widowed respondents described daughters as providing more stimulation, ego support and utility than friends. Respondents also reported that relationships with daughters were stronger than those with friends. Married women described relationships with both daughters and friends as more stimulating than widowed women. The value of assessing qualitative indices compared to quantitative indices of later life relationships is discussed.  相似文献   
23.
24.
Abstract: Evaluation of strategies to improve opportunistic recruitment via general practice of women overdue for a cervical smear requires an accurate behavioural measure. As part of an experimental trial to evaluate the effect of a postgraduate workshop on preventive care, we conducted this methodological study to determine the accuracy of women's recall of an opportunistic discussion about cervical screening, by comparing it against audiotapes ( n = 524). Taking the taped evidence of the trainee's verbal behaviour as the gold standard, sensitivity was 85 per cent (95 per cent confidence interval (CI) 73.1 to 92.0 per cent) and specificity was 78 per cent (CI 73.9 to 81.6 per cent). Given the low rate of opportunistic recruitment by trainees in the main study, only one–third of positive recollections by women of an opportunistic discussion about cervical screening were correct. Until other measures have been validated, women's recall may continue to be used to measure general practitioners' behaviour, but an appreciation of likely bias is recommended.  相似文献   
25.
PURPOSETo evaluate the effect of MR contrast dose versus delayed imaging time on the detection of metastatic brain lesions based on lesion size.METHODSContrast MR examinations with gadoteridol were obtained in 45 patients with brain metastases. The patients were divided into two groups: 16 received cumulative standard dose (0.1 mmol/kg) and 29 received cumulative triple dose (0.3 mmol/kg). Both groups were evaluated at two dose levels (lower dose and higher dose) with two separate injections. Each patient received an initial bolus injection of either 0.05 (cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immediately.RESULTSThere was no difference in the detection rate for lesions larger than 10 mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate.CONCLUSIONIn the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose.  相似文献   
26.
27.
Low-income minority patients from East St. Louis, Illinois, a depressed midwestern urban city, who had visited acute care settings with asthma symptoms, participated in a focus group. Questions were constructed around the Health Belief Model to characterize participants' experiences in receiving asthma care, their confidence in long-term asthma self-management, barriers they perceived to managing their asthma, and recommendations they would make for improving asthma care in their community. Analysis of comments suggests an appreciable understanding of asthma triggers, limited coping behaviors for asthma symptoms, very limited practice of active asthma management, perception of the health care system as frequently insensitive to their needs or their knowledge of their own care, exchange of well-articulated information regarding how to deal with the system, and an apparent lack of awareness of any potential contribution of patient education or support system.  相似文献   
28.
表小檗碱对α受体的作用   总被引:2,自引:0,他引:2  
王嘉陵  方达超 《药学学报》1990,25(4):289-292
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择  相似文献   
29.
Neutrophil bactericidal activity was assessed in patients with type 1 (n=45) and Type 2 diabetes mellitus (n=68) and non-diabetic control subjects (n=40) by measurement of whole blood chemiluminescence. Though chemiluminescence values tended to be highest in the non-diabetic subjects these differences were not statistically significant (mean ± SD) (2.73 ± 1.65 mV (controls), 2.33 ± 1.41 mV (Type 1 diabetes) and 2.38 ± 1.12 mV (Type 2 diabetes), F=1.12, p=0.33). Significant negative correlations were evident, however, in patients with both Type 1 and Type 2 diabetes between chemiluminescence and glycated haemoglobin (rs=-0.35, p=0.005 (Type 1), rs=-0.45, p=0.002 (Type 2), fructosamine (rs=-0.36, p=0.003 (Type 1), rs=-0.42, p=0.004 (Type 2)), and random blood glucose (rs=-0.25, p=0.04 (Type 1), rs=-0.48, p=0.001 (Type 2)). Changes in whole blood chemiluminescence in a further group of 10 patients with Type 2 diabetes mellitus commenced on insulin therapy were followed for 21 days. Serum fructosamine concentrations fell significantly over this time (524 ± 58 μmol l?1 to 405 ± 47 μmol l?1, p<0.001), however, although chemiluminescence values tended to rise these changes were not statistically significant (1.01 ± 0.38 mV to 1.60 ± 0.91 mV, S=4.24, df=5, p=0.52). These results suggest that impaired neutrophil bactericidal function is associated with poor blood glucose control. While it is likely that neutrophil bactericidal function will improve as blood glucose control improves, further studies are required both to confirm this and to demonstrate a reduction in the incidence of clinical bacterial infection.  相似文献   
30.
For almost three decades, many have regarded general hospital psychiatric units as the most appropriate setting for acute treatment of persons with serious mental illness who were once treated mostly in state hospitals. The extent to which this transfer has taken place and the differences between public and private general hospitals have been unclear. Using data from the 1988 National Mental Health Facilities Study and published data from the 1970s, the authors found that nearly half of all general hospitals providing psychiatric services treat persons with serious mental illness. Significant differences in case and payer mix were observed between public and private general hospitals, although these differences were smaller than in the 1970s. The findings suggest increased involvement by private general hospitals in treating patients reimbursed by public payers, but the findings also indicate that persons with serious mental illness and those using Medicaid are still more prevalent in public general hospitals than in private ones.  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