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   1008篇
  免费   72篇
  国内免费   29篇
耳鼻咽喉   32篇
儿科学   33篇
妇产科学   17篇
基础医学   115篇
口腔科学   8篇
临床医学   119篇
内科学   170篇
皮肤病学   12篇
神经病学   78篇
特种医学   86篇
外科学   159篇
综合类   27篇
一般理论   1篇
预防医学   57篇
眼科学   5篇
药学   98篇
中国医学   2篇
肿瘤学   90篇
  2021年   9篇
  2020年   5篇
  2019年   16篇
  2018年   12篇
  2017年   16篇
  2016年   5篇
  2015年   15篇
  2014年   15篇
  2013年   29篇
  2012年   42篇
  2011年   41篇
  2010年   20篇
  2009年   28篇
  2008年   39篇
  2007年   52篇
  2006年   40篇
  2005年   31篇
  2004年   51篇
  2003年   51篇
  2002年   50篇
  2001年   48篇
  2000年   48篇
  1999年   36篇
  1998年   33篇
  1997年   20篇
  1996年   17篇
  1995年   16篇
  1994年   17篇
  1993年   23篇
  1992年   27篇
  1991年   21篇
  1990年   13篇
  1989年   20篇
  1988年   18篇
  1987年   11篇
  1986年   11篇
  1985年   14篇
  1984年   15篇
  1983年   12篇
  1982年   12篇
  1981年   9篇
  1980年   15篇
  1979年   8篇
  1978年   15篇
  1977年   10篇
  1976年   10篇
  1975年   6篇
  1973年   5篇
  1970年   5篇
  1968年   4篇
排序方式: 共有1109条查询结果,搜索用时 46 毫秒
1.
Interleukin (IL)-13 plays a central role in asthma pathogenesis by binding to the IL-13 receptor, which is a heterodimer composed of the IL-13 receptor alpha1 subunit (IL-13Ralpha1) and IL-4Ralpha. The genetic diversity at the IL-13Ralpha1 gene (IL13RA1) locus on chromosome Xq24 was characterised and the association of identified polymorphisms with asthma and atopy phenotypes examined. The promoter and coding region of IL13RA1 were screened for common genetic variants, and polymorphisms found were genotyped in a large cohort of 341 asthmatic Caucasian families (each containing at least two asthmatic siblings) and 182 nonasthmatic control subjects. Genetic association was determined using case-control and transmission disequilibrium test analyses. Two common polymorphisms were identified, a newly found thymidine (T) to guanine (G) transition of nucleotide -281 (-281T>G) single nucleotide polymorphism in the IL13RA1 promoter and the previously described 1365A>G variant in the IL13RA1 proximal 3' untranslated region. No significant association of either -281T>G or 1365A>G with risk of asthma or atopy phenotypes was found, apart from a suggestive association between the IL13RA1 -281T/1365A haplotype and raised total serum immunoglobulin E levels in adult female asthmatics. These findings indicate that the interleukin-13 receptor alpha1 subunit gene -281T>G and 1365A>G polymorphisms do not contribute to asthma susceptibility or severity, although the interleukin-13 receptor alpha1 subunit gene locus might be involved in the control of immunoglobulin E production.  相似文献   
2.
OBJECTIVE: To estimate medium-term success after a technique for ultrasound-guided sclerotherapy for superficial chronic venous disease. DESIGN: A prospective study in a single unit with ultrasound surveillance after treatment. MATERIALS: Results after 1189 treatment sessions for 807 venous saphenous veins and related tributaries or non-saphenous tributaries in 489 patients. METHODS: Univariate life table analysis determined primary and secondary success rates. Multivariate Cox regression analysis detected covariates that affected outcome. RESULTS: Primary and secondary success rates at 36 months for all veins were 52.4% (95%CI 46-58%) and 76.8% (95%CI 71-82%). Cox regression analysis for primary success for all veins showed significantly worse results for saphenous veins compared to tributaries (HR 3.72 - 95%CI 1.9 to 7.3). Cox regression for all saphenous veins showed independently worse results for patients less than 40 years age (HR 2.16 - 95%CI 1.27-3.66), small compared to great saphenous veins (HR 1.58 - 95%CI 1.11-2.24), veins greater than 6mm diameter compared to smaller veins (HR 2.22 - 95%CI 1.40-3.50), liquid compared to foam sclerotherapy (HR 2.20 - 95%CI 1.28-3.78), lower volumes of sclerosant compared to volumes greater than 12 ml (HR 0.51 - 95%CI 0.33-0.81) and highly diluted compared to concentrated sclerosant (HR 2.05 - 95%CI 1.21-3.46) with worse results using highly diluted or undiluted 3% sclerosant compared to a 1.5% concentration. There were no significant differences for primary success for saphenous veins for date of procedure, sex, side, primary or recurrent varicose veins, or commercial type of sclerosant. CONCLUSIONS: Ultrasound-guided sclerotherapy gives satisfactory results if it is accepted that treatment may need to be repeated to achieve secondary success. Results provide a basis for further research to explore factors that might affect outcome. Younger patients with larger diameter saphenous veins may warrant alternative forms of treatment, particularly for small saphenous reflux.  相似文献   
3.
4.
Renz  JF; Kalf  GF 《Blood》1991,78(4):938-944
Chronic exposure of humans to benzene (BZ), a myelotoxin, causes aplastic anemia and acute leukemia. The stromal macrophage that produces interleukin-1 (IL-1), a cytokine essential for hematopoiesis, is a target of BZ's toxicity. Monocyte dysfunction and decreased IL-1 production have been shown to be involved in aplastic anemia in humans. Hydroquinone (HQ), a toxic bone marrow (BM) metabolite of BZ, causes time- and concentration-dependent inhibition of processing of the 34-Kd pre-interleukin-1 alpha (IL-1 alpha) to the 17-Kd mature cytokine in murine P388D1 macrophages and BM stromal macrophages, as measured by Western immunoblots of cell lysate proteins using a polyclonal rabbit antimurine IL-1 alpha antibody. HQ over a 10-fold concentration range had no effect on the lipopolysaccharide (LPS)-induced production of pre- IL-1 alpha precursor or on cell viability or DNA and protein synthesis. Stromal macrophages obtained from the femoral BM of C57Bl/6 mice exposed to BZ (600 or 800 mg/kg body weight) for 2 days were incapable of processing the 34-Kd pre-IL-1 alpha to the mature 17-Kd cytokine when stimulated in culture with LPS. Stromal macrophages from mice coadministered BZ and indomethacin, a prostaglandin H synthase (PHS) inhibitor that has been shown to prevent BZ-induced myelotoxic and genotoxic effects in mice when coadministered with benzene were able to convert the pre-IL-1 alpha to mature cytokine. Administration of recombinant murine IL-1 alpha (rMuIL-1 alpha) to mice before a dose of BZ that causes severe depression of BM cellularity completely prevents BM depression, most probably by bypassing the inability of the stromal macrophage in BZ-treated animals to process pre-IL-1 alpha to the mature cytokine.  相似文献   
5.
A 38 year old woman who had undergone irradiation during infancy for a left facial cutaneous arteriovenous malformation sequentially developed complete palsies of the ipsilateral VII, V, XI, IX, X, XII and VI cranial nerves. Apart from optic and olfactory nerve damage there are few reports of radiotherapy causing cranial nerve injury. We link the unusually extensive and progressive neural damage and the prolonged latency to the patient''s age at time of irradiation.  相似文献   
6.
Efficacy of Intraoperative Cooling Methods   总被引:3,自引:0,他引:3  
Background: Patients may require perioperative cooling for a variety of reasons including treatment of a malignant hyperthermia crisis and induction of therapeutic hypothermia for neurosurgery. The authors compared heat transfer and core cooling rates with five cooling methods.

Methods: Six healthy volunteers were anesthetized with desflurane and nitrous oxide. The cooling methods were 1) circulating water (5 [degree sign] Celsius, full-length mattress and cover), 2) forced air (10 [degree sign] Celsius, full-length cover), 3) gastric lavage (500 ml iced water every 10 min), 4) bladder lavage (300 ml iced Ringer's solution every 10 min), and 5) ice-water immersion. Each method was applied for 40 min or until the volunteers' core temperatures approached 34 [degree sign] Celsius. The volunteers were rewarmed to normothermia between treatments. Core cooling rates were evaluated using linear regression.

Results: The first volunteer developed abdominal cramping and diarrhea after gastric lavage. Consequently, the technique was not again attempted. Bladder lavage increased heat loss 10 [nearly =] 10 W and decreased core temperature 0.8 +/- 0.3 [degree sign] Celsius/h (r2 = 0.99 +/- 0.002; means +/- SD). Forced-air and circulating-water cooling comparably increased heat flux, [nearly =] 170 W. Consequently, core cooling rates were similar during the two treatments at 1.7 +/- 0.5 [degree sign] Celsius/h (r2 = 0.99 +/- 0.001) and 1.6 +/- 1.1 [degree sign] Celsius/h (r2 = 0.98 +/- 0.02), respectively. Immersion in an ice water slurry increased heat loss [nearly =] 600-800 W and decreased core temperature 9.7 +/- 4.4 [degree sign] Celsius/h (r sup 2 = 0.98 +/- 0.01). Immersion cooling was associated with an afterdrop of [nearly =] 2 [degree sign] Celsius.  相似文献   

7.
8.
9.
10.

Background  

Genetic polymorphisms of the TCF7L2 gene are strongly associated with large increments in type 2 diabetes risk in different populations worldwide. In this study, we aimed to confirm the effect of the TCF7L2 polymorphism rs7903146 on diabetes risk in a Brazilian population and to assess the use of this genetic marker in improving diabetes risk prediction in the general population.  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