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   47623篇
  免费   2746篇
  国内免费   163篇
耳鼻咽喉   872篇
儿科学   1681篇
妇产科学   817篇
基础医学   6193篇
口腔科学   1072篇
临床医学   3682篇
内科学   11717篇
皮肤病学   1594篇
神经病学   4282篇
特种医学   1320篇
外科学   5896篇
综合类   221篇
一般理论   19篇
预防医学   3992篇
眼科学   1161篇
药学   2845篇
中国医学   146篇
肿瘤学   3022篇
  2024年   38篇
  2023年   318篇
  2022年   411篇
  2021年   1242篇
  2020年   699篇
  2019年   1307篇
  2018年   1711篇
  2017年   1139篇
  2016年   1142篇
  2015年   1299篇
  2014年   1465篇
  2013年   2040篇
  2012年   3471篇
  2011年   3761篇
  2010年   1999篇
  2009年   1634篇
  2008年   3031篇
  2007年   3203篇
  2006年   2972篇
  2005年   2923篇
  2004年   2674篇
  2003年   2528篇
  2002年   2331篇
  2001年   1194篇
  2000年   1426篇
  1999年   1107篇
  1998年   314篇
  1997年   243篇
  1996年   212篇
  1995年   152篇
  1994年   112篇
  1993年   96篇
  1992年   361篇
  1991年   267篇
  1990年   234篇
  1989年   172篇
  1988年   168篇
  1987年   172篇
  1986年   126篇
  1985年   120篇
  1984年   95篇
  1983年   75篇
  1982年   31篇
  1981年   40篇
  1980年   35篇
  1979年   63篇
  1976年   33篇
  1974年   34篇
  1973年   41篇
  1972年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Germ cell tumors of the testes represent a unique paradigm of diseases which can be cured even in extremely advanced phase. Unfortunately, this makes them unique among adult solid tumors. Seminoma and non seminoma are relatively rare with approximatively 25,000 patients in Europe per year, but numbers are increasing world wide. Different strategies are needed depending on stage and prognostic scores. Seminoma is extremely sensitive to radiation therapy and chemotherapy, while all germ cell tumors show a very good response to chemotherapy. Clinical stage I seminoma is currently treated with radiation, single course carboplatin or surveillance policy. Clinical stage I non seminoma can also be approached with different strategies such as retroperitoneal lymph node dissection, observation or one-two courses of standard chemotherapy. Stage II seminoma may be treated with either radiation or chemotherapy, while for all advanced stages chemotherapy is mandatory. Since the mid-eighties PEB (Cisplatin, Etoposide and Bleomycin) is the regimen of choice and no other schedule has proved superior in terms of efficacy. Surgery on the residual disease is crucial to the whole strategy and should be performed or attempted in all cases. Consequently, the correct treatment strategy for these tumors does not depend only on the ability of a single physician, but on a skilled team specialized in this particular tumor. Second line therapies (VeIP, PEI, TIP) can cure 25%–40% of patients, but improved strategies for resistant tumors are desperately needed. High-dose chemotherapy has shown very good results in some studies while being less impressive in others. In any case, it should remain an option for relapsing patients and could be used in some cases of upfront chemotherapy in patients with slow marker decline, but this should only be considered in referring centers.  相似文献   
43.
A novel assay for factor XIII is described that utilizes exclusively small synthetic peptides as substrates for the cross-linking reaction catalyzed by activated factor XIII (FXIIIa). The acyl donor substrate (selection peptide) is immobilized on a microplate via biotin while the acyl acceptor substrate (detection peptide) is labeled with the fluorochrome Oregon green to allow sensitive detection without the need for secondary enzyme systems for signal amplification. Starting with an amino acid sequence from the fibrin gamma-chain (GQQHHLGGAKQAGDV) as a prototype peptide, the influence of amino acid exchanges were investigated with respect to their impact on the FXIIIa-catalyzed reaction. It was found that FXIIIa readily accepts a broad range of substrate peptides, with a proline neighboring the essential lysine having the most detrimental effect. The assay appears to be valuable for the molecular characterization of factor XIII and may be used for a deeper investigation into the substrate requirements of this final enzyme of wound repair, and eventually also for the characterization of other transglutaminases.  相似文献   
44.
BACKGROUND: Artemisia species pollen represents a major cause of allergy in Central Europe. Variations in the pollen season, the influence of climate variables and the prevalence of pollinosis to it were analyzed in Poznan, in western Poland between 1995 and 2004. METHODS: A Hirst volumetric spore trap was used for atmospheric sampling. Pollination date trend analysis and Spearman correlation tests were performed. Skin prick tests (SPT) and allergen specific immunoglobulin (lg)E antibody measurements were performed in 676 and 524 patients, respectively. RESULTS: The Artemisia species pollen season grew longer due to a clear advance in the starting day and only a slightly earlier end point; the peak day also came slightly earlier. Rainfall in the first fortnight of July highly influenced pollen season severity. Temperature was directly correlated with daily Artemisia species pollen levels; relative humidity was inversely correlated. Twelve percent of patients had a positive SPT reaction to Artemisia species. Their symptoms were rhinitis and conjunctivitis (15%), atopic dermatitis (15%), chronic urticaria (14.3%), bronchial asthma (2.4%), and facial and disseminated dermatitis (1.3%). Elevated specific IgE concentrations were detected in the sera of 10.1% of patients. CONCLUSIONS: Artemisia species pollen is an important cause of pollinosis in western Poland. Pollen season intensity is highly influenced by rainfall in the previous weeks. Trends towards earlier season starts and longer duration, possibly caused by climate change, may have an impact on the allergic population.  相似文献   
45.
OBJECTIVE: To study the effect of seasons on the health-related quality of life (HRQL) of asthmatic children. METHODS: Four groups of asthmatic children 7 to 14 years old were recruited by pediatricians during each season of the year. Their HRQL was assessed by means of the Paediatric Asthma Quality of Life Questionnaire (PAQLQ). Other factors surveyed were asthma severity, atopy, medical treatment, immunotherapy, obesity, parental smoking, and anti-allergic measures. RESULTS: The mean (SD) overall PAQLQ score was highest in summer at 6.2 (1.0) and lowest in autumn at 5.5 (1.2). The same trend was found for domains in summer and autumn, respectively: symptoms, 6.2 (1.0) vs 5.4 (1.4); emotions, 6.5 (0.8) vs 6.0 (1.0); and activities, 5.9 (1.4) vs. 5.0 (1.5). Factors such as male gender (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.41-0.87), being on immunotherapy (OR, 0.59; 95% CI, 0.38-0.92), living in an urban environment (OR, 0.56; 0.33-0.93), and residing on the northern coast of Spain along the Bay of Biscay (OR, 0.56; 0.36-0.89) were independent protective factors against having a total PAQLQ score in the lower tertile. Conversely, being recruited in a primary care setting (OR, 1.55; 1.01-2.38) and having more severe asthma were risks for being in the lower tertile. CONCLUSIONS: Irrespective of the severity of the disease, season has a significant influence on the HRQL of asthmatic children.  相似文献   
46.
47.
PURPOSE: Patient preferences for treatment choices may depend on patient characteristics. Using standard gamble (SG) and willingness to pay (WTP), this study compares preferences for treatment of mandibular fracture among patients in a low-income urban area. PATIENTS AND METHODS: Surveys of African-American and Hispanic adults receiving treatment at King/Drew Medical Center for either mandibular fracture (n = 98) or third molar removal (n = 105) were used to investigate differences in patient characteristics across treatment groups (third molar vs fracture) and treatment preference (wiring vs surgery). RESULTS: The fracture patients were willing to pay more to restore function without scarring or nerve damage than were the third molar patients. Patients who chose surgery were willing to accept a greater risk of possible nerve damage or scarring than those who chose wiring. Among 15 potential predictors of SG and WTP studied in 4 subgroups defined by actual treatment and treatment preference, significant predictors varied, with associations for education and clinical experience for SG and associations with income and psychosocial predictors for WTP. CONCLUSIONS: SG and WTP capture different domains of health values in patients. There is considerable heterogeneity in relationships among patient characteristics and patient preferences across subgroups defined by actual treatment and treatment preferences.  相似文献   
48.
OBJECTIVE: The purpose of the study was to analyze the clinical and radiographic features of central odontogenic myxomas (OM) of the jaws diagnosed over 23 years in a black South African patient sample. STUDY DESIGN: Records of 30 cases of OMs with radiographs of diagnostic quality were retrieved from 52 cases of histopathologically verified OMs from the archives of the Oral Health Center at the University of Limpopo, South Africa. The age, sex, size, location, and radiographic features were compared with the literature. RESULTS: The study consisted of 21 females and 9 males. The correlation between age and size of the tumor was found to be statistically significant (P = .004). Septa were shown to be either reorientated cortical bone or sheets of dense fibrous connective tissue. Indistinct borders mimicked malignancy. The most common radiographic feature was the tennis-racket appearance. CONCLUSIONS: Variations in radiographic presentation make a radiological differential interpretation of OM challenging because the radiographic features overlap with those of other benign and malignant neoplasms.  相似文献   
49.
50.
Hepatic encephalopathy is a reversible state of altered cognition that may occur in patients with acute or chronic liver disease or porto-systemic shunt, and in which known neurological or psychiatric signs may develop. Nitrogenated substances from intestinal digestion reach the brain without being cleared by their passage through the liver due to the presence of porto-systemic shunt. We report two cases of patients with porto-systemic shunt diagnosed with recurrent chronic hepatic encephalopathy refractory to conventional medical treatment. They were satisfactorily treated with shunt embolization using interventionist radiology techniques.  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