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   1424篇
  免费   57篇
  国内免费   4篇
耳鼻咽喉   20篇
儿科学   23篇
妇产科学   20篇
基础医学   149篇
口腔科学   29篇
临床医学   75篇
内科学   483篇
皮肤病学   78篇
神经病学   142篇
特种医学   18篇
外科学   178篇
综合类   8篇
一般理论   1篇
预防医学   85篇
眼科学   13篇
药学   76篇
肿瘤学   87篇
  2024年   1篇
  2023年   13篇
  2022年   4篇
  2021年   30篇
  2020年   12篇
  2019年   43篇
  2018年   49篇
  2017年   22篇
  2016年   23篇
  2015年   34篇
  2014年   35篇
  2013年   59篇
  2012年   137篇
  2011年   119篇
  2010年   77篇
  2009年   48篇
  2008年   108篇
  2007年   100篇
  2006年   98篇
  2005年   101篇
  2004年   94篇
  2003年   86篇
  2002年   78篇
  2001年   30篇
  2000年   20篇
  1999年   16篇
  1998年   6篇
  1997年   3篇
  1996年   3篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1990年   4篇
  1989年   6篇
  1988年   4篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   2篇
  1971年   1篇
  1969年   1篇
排序方式: 共有1485条查询结果,搜索用时 15 毫秒
111.
112.
BACKGROUND: This study ascertained the effect of S-adenosyl-L-methionine (SAMe) administration on the ischemia-reperfusion injury associated with pig liver transplantation from non-heart-beating donors (NHBDs) after prolonged warm ischemia. METHOD: Twenty-five animals underwent transplantation with an allograft from an NHBD. After donor cardiac arrest, cardiopulmonary bypass and normothermic recirculation (NR) were performed for 30 min. Ten animals were given SAMe during NR. Donors were cooled to 15 degrees C, and liver procurement was performed. RESULTS: SAMe reduced histologic liver damage 5 days after transplantation. The necrotic area affected 15.9%+/-14.5% of the liver biopsies in controls and 7.4%+/-9% in SAMe livers. Six of eight controls and only one of eight survivors in the SAMe group developed ischemic cholangitis. SAMe reduced apoptosis of hepatocytes 5 days after transplantation and apoptosis of sinusoidal endothelial cells at reperfusion and at 5 days. SAMe increased energy charge at the end of NR and favored the balance between adenosine and xanthine. It was also associated with higher portal blood flow (740+/-59.2 vs. 475.2+/-65.0 mL/min-1/m-2), hepatic hyaluronic acid extraction (132+/-72.2 vs. -205.8+/-64.6 microg/L), and lower levels of alpha-glutathione-S-transferase after reperfusion (2,601%+/-581% with respect to baseline vs. 6,488%+/-5,612%). CONCLUSION: SAMe administration during liver procurement from NHBDs prevents liver endothelial, parenchymal, and biliary tract damage. The protective role of SAMe may be partially mediated by the effect of adenosine during liver procurement.  相似文献   
113.
PURPOSE: A prospective Phase II trial was carried out to evaluate the effectiveness of erythropoietin in improving or maintaining performance status as determined by the Karnofsky performance status (KPS) score and hemoglobin (Hb) levels in lung cancer patients treated with concurrent chemoradiation (CH-RT). METHODS AND MATERIALS: A total of 51 patients with lung cancer (11 with small-cell, limited stage and 40 with non-small-cell disease, 17 with Stage IIIA and 23 with Stage IIIB), who underwent three different concurrent CH-RT protocols were enrolled. Baseline Hb and KPS values were recorded, as were the nadir Hb and KPS values before concurrent CH-RT. The final Hb and KPS values were recorded the last week of concurrent CH-RT. An Hb level of 相似文献   
114.
OBJECTIVE: To determine optimum anthropometric cutoffs for predicting the likelihood ratios of type 2 diabetes mellitus (DM) and hypertension (HT) in Mexicans. RESEARCH METHODS AND PROCEDURES: Data from a randomly selected, nationally representative health survey (2000) with 11,730 men [37.4 (+/- 12.9) years] and 26,647 women [37.3(+/- 12.9) years] were assessed for values of body mass index (BMI) and waist circumference (WC) for predicting DM or HT by receiver operating characteristic curve analyses. Likelihood ratios for DM and HT were calculated, and BMIs or WCs for public-health screening were developed. Subanalyses included regional data. RESULTS: Likelihood ratios of DM and HT increased from BMI values of 22 to 24 kg/m(2) in both sexes and with WC values of 75 to 80 cm in men and 70 to 80 cm in women. The best BMI cutoffs for predicting DM were 26.3 to 27.4 kg/m(2) in men and 27.7 to 28.9 kg/m(2) in women, with similar values for HT, i.e., 26.2 to 27.0 kg/m(2) and 27.7 to 28.5 kg/m(2), for men and women, respectively; WC cutoffs for DM were 93 to 98 cm in men and 94 to 99 cm in women, and cutoffs for HT were 92 to 96 cm and 93 to 96 cm for men and women, respectively. The WC cutoffs had higher sensitivity and specificity than those of BMI. DISCUSSION: The risk for DM and HT starts at lower levels of BMI and WC than those suggested by WHO. WC is a better discriminator than BMI measures for use in public health.  相似文献   
115.
The very few reference epidemiological studies on myelodysplastic syndromes (MDS) have been carried out in Europe: Germany, France, UK and Sweden. We present the first Spanish study on the incidence and characteristics of MDS. The incidence rates, distribution by FAB subtypes, sex and age groups are within the ranges established by the reference studies with minimal differences which we point out and attempt to explain.  相似文献   
116.
Allergic rhinitis is an inflammatory disease associated with local leukotriene release during periods of symptoms. Zileuton, a leukotriene synthesis inhibitor, is known to inhibit the release of leukotriene B4. Because we previously showed that leukotriene B4 is a potent mediator of neutrophil-dependent nasal secretion, we investigated whether Zileuton inhibited allergen-induced nasal secretion. Using a newly developed method for isolating and superfusing a nasal segment, we examined the effect of Zileuton on nasal secretion and neutrophil recruitment in ragweed-sensitized dogs. Instillation of ragweed into the nasal segment caused time-dependent increases in the volume of airway fluid and the recruitment of neutrophils. Zileuton prevented ragweed-induced neutrophil recruitment and nasal secretion. These results indicate that leukotrienes are important mediators of allergy-induced nasal secretion in dogs. Future clinical studies in allergic patients will determine whether there is a therapeutic role for leukotriene synthesis inhibitors in modulating neutrophil recruitment and hypersecretion in the nose.  相似文献   
117.
Developing SCAR markers to study predation on Trialeurodes vaporariorum   总被引:6,自引:0,他引:6  
DNA markers of Trialeurodes vaporariorum were developed to detect remains of these whitefly in the gut of the predator Dicyphus tamaninii. A 2400-bp DNA fragment of T. vaporariorum, absent in other closely related prey species and in the predator banding pattern, was identified by random amplified polymorphic DNA (RAPD) analysis. After cloning and sequencing this fragment, two pairs of sequence-characterized amplified region (SCAR) primers were developed, amplifying single bands of 2100 bp and 310 bp, respectively. Detection of T. vaporariorum DNA in the predator gut was only possible using the primers that amplified the shortest fragment. Specificity tests performed with this pair of primers showed the presence of the 310-bp band for T. vaporariorum in all stages.  相似文献   
118.
119.

Background  

Declining physical activity is associated with a rising burden of global disease. There is little evidence about effective ways to increase adherence to physical activity. Therefore, interventions are needed that produce sustained increases in adherence to physical activity and are cost-effective. The purpose is to assess the effectiveness of a primary care physical activity intervention in increasing adherence to physical activity in the general population seen in primary care.  相似文献   
120.
OBJECTIVES: To develop the first Spanish Pediatric Trauma Registry to collect and evaluate infomation concerning aspects of injuries in our pediatric population. METHODS: From January 1995 to August 1998, 35,946 children younger than 16 years were treated in our hospital for acute injury: 1500 were admitted and included in our database. Our file registry consists of 108 data points including: patient identification, type, place and mechanism of injury, pre-hospital care, transport, assessment on admission, severity scores, diagnostic studies, injuries, treatment morbidity and mortality. RESULTS: Accidents were more frequent in males (68%) than in females. The predominant age group was 12-15 years of age (34%). Accidents were more frequent in the street (35.1%) than at home (18.9%) or school (13%). Falls and traffic-related accidents were the leading cause of injury (39% and 21.2%, respectively). Two hundred and thirty-five (15.7%) had a Pediatric Trauma Score < or = 8. Fifty of these sustained multiple trauma (33%) (Injury Severity Score > or = 15). Musculoskeletal and head trauma were the most frequent injuries (48.5% and 42.0%, respectively). Surgical or orthopedic procedures were performed in 906 patients (56.5%). The average length of stay was 4.5 days (range 1-93 days). Functional impairment in children older than 4 years of age was found in 413 children (33.3%). We encountered 7 deaths in the 1500 patients, or an overall mortality of 0.5%. These 7 deaths were only seen in the I.S.S. > or = 15 group (50 patients) with 14% mortality. CONCLUSIONS: The goals of this Registry are to establish the epidemiology of our injured pediatric population, to review patient care, to develop prevention programs and to compare results with other centers so that potential deficiencies can be corrected.  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