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   3833篇
  免费   442篇
  国内免费   27篇
耳鼻咽喉   36篇
儿科学   171篇
妇产科学   65篇
基础医学   351篇
口腔科学   64篇
临床医学   401篇
内科学   892篇
皮肤病学   205篇
神经病学   326篇
特种医学   193篇
外国民族医学   1篇
外科学   692篇
综合类   156篇
现状与发展   30篇
一般理论   2篇
预防医学   245篇
眼科学   88篇
药学   146篇
中国医学   16篇
肿瘤学   222篇
  2024年   22篇
  2023年   198篇
  2022年   52篇
  2021年   101篇
  2020年   94篇
  2019年   89篇
  2018年   139篇
  2017年   112篇
  2016年   107篇
  2015年   118篇
  2014年   174篇
  2013年   181篇
  2012年   222篇
  2011年   206篇
  2010年   156篇
  2009年   195篇
  2008年   168篇
  2007年   207篇
  2006年   145篇
  2005年   145篇
  2004年   123篇
  2003年   101篇
  2002年   93篇
  2001年   90篇
  2000年   95篇
  1999年   93篇
  1998年   62篇
  1997年   86篇
  1996年   64篇
  1995年   53篇
  1994年   59篇
  1993年   57篇
  1992年   49篇
  1991年   32篇
  1990年   50篇
  1989年   58篇
  1988年   49篇
  1987年   32篇
  1986年   23篇
  1985年   27篇
  1984年   20篇
  1983年   10篇
  1982年   15篇
  1981年   18篇
  1980年   20篇
  1979年   11篇
  1978年   8篇
  1977年   11篇
  1976年   21篇
  1975年   11篇
排序方式: 共有4302条查询结果,搜索用时 0 毫秒
11.
Between 1968 and 1985, 80 children underwent correction of total anomalous pulmonary venous drainage. There were 47 boys and 33 girls whose ages ranged from 3 days to 16 years (median 2 months, interquartile range 5 years). Seventy (87.5%) were less than 1 year of age at operation. Fifty-eight (72.5%) weighed less than 5 kg, the range being 1.6 to 42 kg (median 3.7 kg, interquartile range 2.4 kg). Forty-five (56%) patients had supracardiac, 14 (17.5%) cardiac, 15 (19%) infracardiac, and 6 (7.5%) had mixed total anomalous pulmonary venous drainage. Follow-up was complete in 78 (97.5%) and ranged from 6 to 189 months (median 58 months, interquartile range 59 months). There were 14 (17.5%) early and six (7.5%) late deaths. Analysis by various factors revealed year of operation as the only factor to affect survival at the 5% level of significance. Early mortality was 29% between 1968-1977 and 11% between 1978-1985 (p = 0.04). Postoperative pulmonary venous obstruction occurred in five (6%) patients between 6 weeks and 3 months after operation. All 5 died, three after reoperation. Five (6%) other children had reoperations, four for residual shunts and one for superior vena caval obstruction.  相似文献   
12.
Endovascular stent-supported angioplasty is a treatment option for atherosclerotic disease of the cervical internal carotid artery in high-risk patients. The traditional transfemoral approach is not suitable for patients who suffer from common femoral artery or abdominal aorta atheropathy. We report a case of carotid stent deployment using the radial route in a 68-year-old man with type B aortic dissection, having severe right internal carotid artery origin stenosis, presenting with ipsilateral retinal ischemic events. Technical aspects of carotid stenting via the radial approach are described and the related literature is discussed.  相似文献   
13.
BACKGROUND: The mainstay of treatment for pemphigus is systemic corticosteroids. Different adjuvants have been used to reduce side-effects of long-term corticotherapy. Gold is an anti-inflammatory drug used in autoimmune diseases, whose use has waned with the advent of new immunosuppressive agents. OBJECTIVE: To study the outcome of the use of intramuscular gold treatment of pemphigus vulgaris refractory to previous therapies. METHODS: Thirteen patients with pemphigus vulgaris who had failed to respond to several prior therapies were treated with aurothiomalate, as a steroid-sparing agent. Patients were monitored to assess disease activity and gold toxicity. RESULTS: Seven patients achieved complete remission. Four patients were able to taper prednisone doses, although pemphigus flared when prednisone was discontinued or reduced. Toxicity was observed in the other two patients. CONCLUSIONS: In 53.4% of the patients, the use of chrysotherapy resulted in the complete clearing of the disease, discontinuation of all systemic therapies and induced a long-term clinical remission. Prednisone doses were able to be reduced in the remaining 46.6%. Any side-effects were reversible with drug discontinuation. Gold therapy showed efficacy as a secondary line treatment in refractory pemphigus vulgaris.  相似文献   
14.
One-hundred and six male children aged 6-23 months with a history of acute watery diarrhoea of less than 72 h duration were randomized to receive either folic acid in a dose of 5 mg at 8-h intervals or placebo for 5 d. There were 54 children in the folic acid group and 52 in the placebo group. The admission characteristics were comparable between the two groups. No significant differences were observed in the intake of oral rehydration solution or stool output between the groups. The mean ± SD of total stool output (g kg−1) was 532 ± 476 vs 479 ± 354 and the duration (h) of diarrhoea was 108 ± 68 vs 103 ± 53 in the folic acid vs placebo group, respectively. The findings, therefore, should have a positive influence on preventing the inappropriate use of folic acid in acute diarrhoea.  相似文献   
15.
16.
Qureshi  Bashir 《JAMA》1998,279(22):1838-1839
  相似文献   
17.
Taxol, a microtubule stabilizer with anticancer activity, mimics the actions of lipopolysaccharide (LPS) on murine macrophages in vitro. Recently, it was shown that taxol-induced macrophage activation was inhibited by the LPS antagonist Rhodobacter sphaeroides diphosphoryl lipid A (RsDPLA). To investigate the mechanisms of taxol-induced macrophage activation, the present study focused on the interaction of LPS, RsDPLA, and taxol in the activation of and binding to macrophages. Taxol alone induced murine C3H/He macrophages to secrete tumor necrosis factor alpha (TNF) and to produce nitric oxide (NO) with kinetics similar to that of LPS. Macrophages from LPS-hyporesponsive C3H/HeJ mice, in contrast, did not yield any detectable TNF and NO production in response to LPS or taxol. RsDPLA inhibited taxol-induced TNF and NO production from C3H/He macrophages in a dose-dependent manner. The inhibition by RsDPLA was specific for LPS and taxol in that RsDPLA did not inhibit heat-killed Listeria monocytogenes- or zymosan-induced TNF production. Polymyxin B blocked the inhibitory effect of RsDPLA on taxol-induced TNF production. The inhibitory activity of RsDPLA appeared to be reversible since macrophages still responded to taxol in inducing TNF production after the RsDPLA was washed out with phosphate-buffered saline prior to the addition of taxol. Taxol-induced TNF production was not inhibited by colchicine, vinblastine, or 10-deacetylbaccatine III. A mutant cell line, J7.DEF3, defective in expression of a CD14 antigen, responded equally well to taxol by producing TNF as did the parent J774.1 cells. This suggested that the activation of macrophages by taxol does not require CD14. Taxol-induced TNF production by the mutant cells was also inhibited by RsDPLA. 125I-labeled LPS and 3H-labeled taxol was reported to bind to J774.1 cells predominantly via CD14 and microtubules, respectively. The binding of 125I-labeled LPS to J7.DEF3 cells was about 30 to 40% of that to J774.1 cells. The binding of 125I-LPS to J774.1 cells was inhibited by unlabeled LPS and RsDPLA but not by taxol. On the other hand, 3H-labeled taxol bound to both J774.1 cells and J7.DEF3 cells in similar time- and dose-dependent manners. The binding of [3H]taxol to these cells was inhibited by taxol but not by LPS or RsDPLA. Although the binding studies failed to examine cross competition for binding to macrophages, a possible explanation of these results is that LPS, RsDPLA, and taxol share the same molecule(s) on murine macrophages for their functional receptor(s), which is neither CD14 nor tubulin.  相似文献   
18.
19.
BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major health problem with an estimated prevalence of 10-15% among smokers. The incidence of moderate COPD, as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD), is largely unknown. AIM: To determine the cumulative incidence of moderate COPD (forced expiratory volume in 1 second/forced vital capacity ratio [FEV1/FVC] <0.7 and FEV1 <80% predicted) and its association with patient characteristics in a cohort of male smokers. DESIGN: Prospective cohort study. SETTING: The city of IJsselstein, a small town in the Netherlands. METHOD: Smokers aged 40-65 years who were registered with local GPs, participated in a study to identify undetected COPD. Baseline measurements were taken in 1998 of 399 smokers with normal spirometry (n = 292) or mild COPD (FEV1/FVC <0.7 and FEV1 >or=80% predicted, n = 107) and follow-up measurements were conducted in 2003. RESULTS: After a mean follow-up of 5.2 years, 33 participants developed moderate COPD (GOLD II). This showed an estimated cumulative incidence of 8.3% (95% CI = 5.8 to 11.4) and a mean annual incidence of 1.6%. No participant developed severe airflow obstruction. The risk of developing moderate COPD in smokers with baseline mild COPD (GOLD I) was five times higher than in those with baseline normal spirometry (one in five versus one in 25). CONCLUSIONS: In a cohort of middle-aged male smokers, the estimated cumulative incidence of moderate COPD (GOLD II) over 5 years was relatively high (8.3%). Age, childhood smoking, cough, and one or more GP contacts for lower respiratory tract problems were independently associated with incident moderate COPD.  相似文献   
20.
The age-related changes in absolute and percentage values of lymphocyte subsets in the peripheral blood of healthy children of different ages (1 month to 13 years) were studied by flow cytometry. The absolute and percentage values for most lymphocyte subpopulations differed substantially with age. Comparisons among age groups from infants through adults revealed progressive declines in the absolute numbers of leukocytes, total lymphocytes, and T, B, and natural killer (NK) cells. The percentages of T cells increased with age. Within the T-lymphocyte population, the CD8+ subset increased but the CD4+ subset decreased, resulting in a declining CD4+/CD8+ ratio. The percentage of B cells declined, but that of NK cells remained unchanged. The percentage of HLA-DR+ T cells increased over time, but their number changed inconsistently. Our findings confirm and extend earlier reports on age-related changes in lymphocyte subpopulations. These data should be useful in the interpretation of disease-related changes, as well as therapy-dependent alterations, in lymphocyte subsets in children of different age groups.  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