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   36037篇
  免费   2564篇
  国内免费   68篇
耳鼻咽喉   331篇
儿科学   1241篇
妇产科学   1013篇
基础医学   4659篇
口腔科学   467篇
临床医学   4717篇
内科学   6477篇
皮肤病学   502篇
神经病学   3833篇
特种医学   751篇
外国民族医学   5篇
外科学   3357篇
综合类   405篇
一般理论   45篇
预防医学   4894篇
眼科学   538篇
药学   2453篇
中国医学   24篇
肿瘤学   2957篇
  2024年   45篇
  2023年   302篇
  2022年   552篇
  2021年   1202篇
  2020年   725篇
  2019年   1089篇
  2018年   1240篇
  2017年   873篇
  2016年   1029篇
  2015年   1064篇
  2014年   1414篇
  2013年   2010篇
  2012年   2897篇
  2011年   3163篇
  2010年   1640篇
  2009年   1391篇
  2008年   2499篇
  2007年   2556篇
  2006年   2318篇
  2005年   2209篇
  2004年   1955篇
  2003年   1675篇
  2002年   1713篇
  2001年   272篇
  2000年   239篇
  1999年   255篇
  1998年   344篇
  1997年   267篇
  1996年   186篇
  1995年   196篇
  1994年   144篇
  1993年   136篇
  1992年   105篇
  1991年   85篇
  1990年   73篇
  1989年   66篇
  1988年   75篇
  1987年   65篇
  1986年   59篇
  1985年   37篇
  1984年   54篇
  1983年   57篇
  1982年   36篇
  1981年   38篇
  1980年   22篇
  1979年   31篇
  1978年   24篇
  1977年   32篇
  1976年   22篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.  相似文献   
22.
23.
Multiple options exist for the prevention of deep vein thrombosis (DVT) in medical inpatients. We sought to determine the cost-effectiveness of low-molecular-weight heparin (LMWH) relative to unfractionated heparin (UFH) for DVT prevention in this setting. We conducted a cost-effectiveness analysis from the perspective of a third-party payer employing a decision model and literature-based estimates for inputs. In the base-case analysis, LMWH had little impact on the rate of DVT. Despite higher acquisition costs, however, LMWHs resulted in net savings. Routine use of LMWH saves approximately US$89 per patient. The lower rate of heparin-induced thrombocytopenia (HIT) with LMWH accounted for this differential. Univariate sensitivity analysis revealed the model was moderately sensitive to the odds ratio of HIT with LMWH and the cost of HIT. Multivariate sensitivity analysis confirmed the LMWH approach dominated financially. 'Worst-case' scenario modeling, where LMWH actually increased the risk for DVT, had little effect on the rate of HIT, and was substantially more costly than UFH, still demonstrated that LMWHs were economically superior. Monte-Carlo simulation indicated the 95% confidence interval around the estimate for savings with LMWH ranged from US$7 to US$373. We conclude that, despite their higher cost, LMWHs for thromboprophylaxis in medical patients result in savings.  相似文献   
24.
Infections caused by extended-spectrum beta-lactamase (ESBL)-producing pathogens, particularly Klebsiella pneumoniae, are increasing. The epidemiology of ESBL-producing K. pneumoniae, the mechanisms of resistance, and treatment strategies for infections caused by these organisms are reviewed.  相似文献   
25.
26.
A 26-year-old man who presented with a 2-year history of intermittent gynecomastia with recent onset of fever, night sweats, and abdominal distension was found to have a left-sided adrenocortical carcinoma with metastases to the liver and spine. Sudden death occurred 1 month after his presentation. At autopsy a saddle pulmonary thromboembolus was found occluding the pulmonary outflow tract, with smaller more peripheral pulmonary thromboemboli. No tumor deposits were identified in the thromboemboli. The thromboemboli had arisen from a tongue of tumor that had grown through the left adrenal vein into the inferior vena cava. Despite a high rate of angio-invasion there are very few reports of sudden death resulting from this phenomenon in patients with adrenocortical carcinoma.  相似文献   
27.
28.
29.
30.
OBJECTIVES: To determine whether the increase in the incidence of injury found for the first summer season in which rugby league (RL) was played in the UK was repeated in subsequent summer seasons. DESIGN: A retrospective and prospective cohort study design. SETTING AND PARTICIPANTS: Injuries were recorded from all players who took part in 141 games over 3 summer seasons (1997 to 1999) for 1 professional team. These were compared against rates from previously collected data for 3 earlier winter and 1 summer season. ASSESSMENT OF RISK FACTORS: For each injury it was recorded in which season it occurred; how many games or training sessions, if any, were subsequently missed; the type, site and severity of injury. MAIN OUTCOME MEASURES: Injuries were reported as rate per 1000 hours, also broken down into severity according to the number of games missed and whether subsequent training sessions were missed. RESULTS: A sustained increase in injury incidence has been found comparing summer RL over RL played in the winter. There was an increase in injury rates for all sites and types, but not all reached significance. CONCLUSIONS: Data collected over 6 seasons indicate a higher risk of sustaining an injury playing summer RL, but the cause may be related to a combination of factors. These may include the ground or weather conditions associated with summer rugby, player characteristics or changes in the game itself and future research needs to investigate these further.  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