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   1167篇
  免费   85篇
耳鼻咽喉   5篇
儿科学   27篇
妇产科学   38篇
基础医学   211篇
口腔科学   24篇
临床医学   81篇
内科学   253篇
皮肤病学   13篇
神经病学   140篇
特种医学   27篇
外科学   77篇
综合类   11篇
预防医学   100篇
眼科学   12篇
药学   115篇
中国医学   2篇
肿瘤学   116篇
  2023年   9篇
  2022年   17篇
  2021年   37篇
  2020年   25篇
  2019年   38篇
  2018年   41篇
  2017年   31篇
  2016年   41篇
  2015年   44篇
  2014年   47篇
  2013年   59篇
  2012年   77篇
  2011年   93篇
  2010年   42篇
  2009年   36篇
  2008年   61篇
  2007年   58篇
  2006年   62篇
  2005年   63篇
  2004年   54篇
  2003年   57篇
  2002年   62篇
  2001年   13篇
  2000年   10篇
  1999年   11篇
  1998年   10篇
  1997年   12篇
  1996年   5篇
  1995年   9篇
  1994年   6篇
  1993年   7篇
  1992年   6篇
  1991年   4篇
  1990年   6篇
  1988年   4篇
  1985年   4篇
  1983年   5篇
  1982年   4篇
  1981年   4篇
  1980年   4篇
  1979年   5篇
  1977年   6篇
  1976年   4篇
  1975年   5篇
  1974年   5篇
  1972年   3篇
  1971年   6篇
  1970年   3篇
  1968年   5篇
  1966年   5篇
排序方式: 共有1252条查询结果,搜索用时 15 毫秒
1.
There is no published data about associations between the state of dentition and bone mass in adolescents. The objective of this study was to investigate whether the prevalence of caries and dental malocclusion is associated with bone mass during growth. In 123 healthy Caucasian subjects (72 males, 51 females) aged 14-18 yr, DMFT figures (decayed teeth, missing teeth, filled teeth) and presence of malocclusion, according to Angle classification, were determined. Participants completed a questionnaire regarding dental hygiene, physical activity level, and consumption of sweets. Anthropometry and pubertal stages were examined. Bone mineral density (BMD) was examined using dual energy X-ray absorptiometry (DXA) in the total body, head, and lumbar spine. No association was found between DMFT (mean+/-SD: 8.33+/-3.9) and BMD or Z-scores for BMD. Malocclusion was found in 49 subjects (39.8%) and was more prevalent in females than males. Malocclusion was associated with lower total BMD independently of body size (p=0.001; Z-scores: -0.21+/-0.27 vs +0.33+/-0.17; p=0.1) in males (but not females), producing odds ratio 1.6 (95% confidence interval: 1.09-2.34%; p=0.02). Head BMD was also lower in the males with malocclusion than in those without (p=0.004). Neither caries nor the tooth loss appear to be associated with BMD during growth. Boys with malocclusion are at higher risk of reduced BMD. This suggests that inadequate bone mass accrual in males coexists with impaired growth of the masticatory system in childhood and adolescence, however, the causal pathway is unknown. Factors that produce malocclusion may also affect bone mass or size but further prospective studies are needed to evaluate the relationship.  相似文献   
2.
Purpose: The prevalence of activated protein C resistance (APCR) and associated thrombotic morbidity among patients who undergo arterial reconstruction were investigated.Methods: Preoperative assays for functional APCR and factor V (Leiden) mutation were performed on 262 patients who underwent arterial reconstructions that consisted of cerebrovascular surgery (109), aortic or iliofemoral procedures (76), or infrainguinal bypass procedures (77). Patients were monitored for thrombotic complications during the postoperative period.Results: Depending on the stringency of the definition used, functional APCR was detected in 10.6% to 22.0% of patients tested. Factor V (Leiden) was found in 5.3% of patients. Thrombotic morbidity consisting of myocardial infarction, cerebrovascular event, or graft thrombosis occurred in 9.9% of patients, who were followed-up for a mean of 4.8 months. No significant overall correlations were found between APCR and thrombotic morbidity. Subgroup analysis revealed significant associations between functional APCR and total early postoperative thrombotic complications and early graft failure, and between factor V (Leiden) and early cerebrovascular events and late graft thrombosis (p < 0.03).Conclusions: Functional APCR is somewhat more prevalent among general vascular surgical patients than in the general population, but factor V (Leiden) is no more prevalent. APCR is not a prominent cause of thrombotic morbidity in contemporary vascular surgery. Nonetheless, it is a sufficiently important potential contributor to morbidity among some subgroups to warrant selective testing and directed therapy pending further study. (J Vasc Surg 1997;25:1054-60.)  相似文献   
3.
Pull-through esophageal intubation with a composite, detachable prosthesis allows insertion of the tube only in the narrowing due to the tumor. Using this easy technique, which permits a convenient low, small 3 millimeter gastrotomy, the intra-abdominal contamination is reduced. The end of the tube does not pass across the cardia, so the patient is free from gastroesophageal reflux and its consequences.  相似文献   
4.
BACKGROUND: The life expectancy of individuals with CF has increased to 33 years. Thus, issues such as quality of life and psychological well-being, previously thought to be of lesser importance than physical well-being, are now recognised as significant factors. This study examined the interrelationships between quality of life, family functioning, individual psychopathology and optimism of adolescents with CF. METHODS: Adolescents attending the CF clinic completed a number of questionnaires. Quality of Life was measured using the Cystic Fibrosis Questionnaire, family functioning by the Family Environment Scale (3rd edition), general psychopathology with the Symptom Checklist-90-Revised and optimism for the future by the Hunter Opinions and Personal Expectations Scale. Disease severity was assessed using the Shwachman score and spirometry at the time of questionnaire completion. RESULTS: The level of psychopathology (12.5% of those 13 years and over) in the group was lower than that reported for young people in Australia (15-20%). The results indicated that young people with a delayed diagnosis and those who are alienated from their families may be in need of additional psychosocial support. The group was hopeful and positive about their future and these attributes were independent of clinical measures of disease severity. In general, these young people scored relatively highly on the quality of life scale. For example the mean standardised score for physical functioning was 70 points, for respiratory symptoms was 63 points and for emotional state was 78 points. Increased levels of psychopathology and lack of hope for the future were however associated with lower ratings on a number of quality of life measures. Family cohesiveness, expressiveness and organization were associated with better psychological functioning in the young people. CONCLUSIONS: Adolescents with CF appear to be a psychologically well functioning and well-adjusted group. These findings support the importance of a more sophisticated model of well-being for adolescents with CF, which explores the young person's views on their quality of life and wider support frameworks rather than relying solely on measures of physical health to gauge well-being.  相似文献   
5.
In the present study, morphological examination of patients from two unrelated Polish families with CADASIL was performed. Using light microscopy, there were evident changes characteristic to the disease. On electron microscopy, deposits of granular osmiophillic material (GOM) were found not only in cerebral arteries and veins but also in cerebral capillaries and vessels of the internal organs. These findings indicate that pathological process in CADASIL is generalized and involves also small vessels devoid of smooth muscle cells. Therefore, we propose to consider a replacement for the name CADASIL that better reflects the morphological picture of the disease like, for example, cerebral autosomal dominant vasculopathy with subcortical infarcts and leukoencephalopathy (CADVaSIL) or, to preserve the commonly known acronym, cerebral autosomal dominant angiopathy with subcortical infarcts and leukoencephalopathy.  相似文献   
6.
The clinical specimens received from patients hospitalized in Department of Thoracic Surgery between 1997 and 2001 were microbiologically examined. The main specimen for microbiological examination was pleural fluid (median 34%). The frequency of specimens from bronchial tree increased significantly (from 4% to 26%) with concurrent decrease of sputum (from 29% to 6%). Among isolated pathogens, Gram negative rods were the most frequent (median 48%) and Pseudomonas sp. was the main pathogen among them. Occurrence of staphylococci was median 22% and Staphylococcus aureus, with a little decrease in analyzed period, was still the main Gram positive pathogen. Simultaneously the occurrence of MRSA in the last three years dropped three times. The number of isolations of yeasts have risen from 5.8% to 10.3%.  相似文献   
7.
8.
Shigella dysenteriae 7 (D7) strain was extracted by using the Westphal water/phenol method and the extract obtained (Aq/Ph 68?C) was found to have the receptor activity against both T2 and T4 phages. It was shown by the receptor neutralization test that the examined substance had receptor sites distinctive for T2 and T4 phages. The receptor sites for phage T2 had common antigen specificity with receptor sites of this phage localized inE. coli B in the lipoprotein fraction; the receptor sites of phage T4 had common antigen specificity with receptor sites to phage T4, localized inE. coli B in Aq/Ph 68? C extract. It is suggested that in spite of the different localization, the receptors for the same phage in the different bacterial species examined have common serological specificity.  相似文献   
9.
10.
The conditions for active sensitization of hamster peritoneal and pleural mast cells and IgE-induced histamine release as well as cell desensitization were defined. Immunization of hamsters with ovalbumin (5 g) in Al/OH/3 gel (5 mg) with several boosters resulted in sensitization of peritoneal and pleural mast cells; in the presence of extracellular Ca++, pH of medium 7.2 and at 37°C these cells released up to 70% of histamine on the challenge with specific antigen. Partial release was observed when the cells were challenged with antigen in the absence of extracellular calcium. The rate of release is high during the first seconds of activation and is complete at 1 min. 30 min preincubation of peritoneal and pleural mast cells in calcium-free conditions (in the presence of 4 mM EDTA) resulted in complete desensitization of cells to subsequent action of antigen in potimal conditions. The present experiments demonstrate, that hamster peritoneal and pleural mast cells can be a useful model system forin vitro studies of the mechanisms of IgE-induced cell activation.  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