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   1827篇
  免费   181篇
耳鼻咽喉   11篇
儿科学   116篇
妇产科学   29篇
基础医学   260篇
口腔科学   25篇
临床医学   200篇
内科学   350篇
皮肤病学   68篇
神经病学   181篇
特种医学   29篇
外科学   136篇
综合类   30篇
一般理论   5篇
预防医学   274篇
眼科学   11篇
药学   132篇
肿瘤学   151篇
  2023年   26篇
  2022年   34篇
  2021年   58篇
  2020年   39篇
  2019年   65篇
  2018年   69篇
  2017年   46篇
  2016年   41篇
  2015年   52篇
  2014年   50篇
  2013年   81篇
  2012年   135篇
  2011年   115篇
  2010年   59篇
  2009年   48篇
  2008年   73篇
  2007年   105篇
  2006年   85篇
  2005年   89篇
  2004年   84篇
  2003年   63篇
  2002年   59篇
  2001年   42篇
  2000年   42篇
  1999年   41篇
  1998年   21篇
  1997年   12篇
  1996年   12篇
  1995年   18篇
  1994年   14篇
  1992年   13篇
  1991年   18篇
  1990年   22篇
  1989年   31篇
  1988年   21篇
  1987年   18篇
  1986年   14篇
  1985年   14篇
  1984年   15篇
  1981年   6篇
  1979年   10篇
  1978年   11篇
  1975年   8篇
  1973年   14篇
  1972年   9篇
  1971年   10篇
  1970年   9篇
  1969年   10篇
  1968年   11篇
  1967年   7篇
排序方式: 共有2008条查询结果,搜索用时 609 毫秒
1.
2.
3.
4.
BACKGROUND: Paediatric audiology services and screening programmes are currently under review. AIMS AND METHODS: To investigate current practice and performance of the school hearing screening programme (SHSP) by means of a questionnaire. RESULTS: SHSP was found to detect previously unrecognised hearing loss at low cost. Wide variation in practice was shown, and the majority of services had no computerised system for data collection. CONCLUSION: There is a need for nationally agreed protocols and quality assurance procedures.  相似文献   
5.

Background  

The aim of the current study is to investigate the relationship between physical anhedonia and psychopathological parameters, pharmacological parameters or motor side-effects in a sample of inpatients with schizophrenia in an acute episode of their illness.  相似文献   
6.
B W Forsyth  P F Canny 《Pediatrics》1991,88(4):757-763
The long-term consequences for infants with problems of feeding and crying behavior remain unknown. The purpose of this research was to determine whether such children are later perceived by their parents as vulnerable and more often have behavior problems and have different personalities than children without problems in infancy. The implications of managing such problems by changing milk formulas is explored. Mothers of 379 infants were enrolled in the postpartum period. Information about problems of feeding and crying behavior was obtained at 4 months. Thirty-six percent of the infants had problems and the formula had been changed for 17%. At 3 1/2 years, 320 (84%) mothers completed a questionnaire. Children who had had problems were more often perceived as vulnerable (relative risk [RR] 1.86; 95% confidence interval [CI] 1.09, 3.19) and more often had behavior problems (RR 1.78; 95% CI 1.03, 3.07). There were no differences in personality. Children whose problems had been managed by changing milk formulas were more often perceived as vulnerable (RR 2.18; 95% CI 1.05, 4.53). Although allergies were reported significantly more often for those children who had had problems, there were no differences in the prevalence of asthma or eczema. Problems of feeding and crying behavior in early infancy and the way they are managed may have long-term implications for the child.  相似文献   
7.
A reproducible animal model is essential for the study of the pathogenesis of chronic rejection. This study investigates: (i) the optimal pre-transplant blood transfusion conditions to induce tolerance in a strongly rejecting rat kidney allograft model (Dark Agouti to Albino-Surgery) and avoiding post-transplant immunosuppression; (ii) the functional and histological changes that occur in long-term surviving kidneys and their similarity to chronic rejection; and (iii) the maintenance of tolerance. Prolonged survival occurred after administration of at least two donor blood transfusions with concomitant cyclosporin A (5 mg/kg per day). The time-span between transfusions appeared to be critical: 4 days was more effective than 2 or 7 days. Ineffective treatment led to death within the first 2 weeks post-transplant with histological evidence of acute graft rejection. Seventy-five per cent of long-term survivors experienced impaired renal function in the first week which improved spontaneously and remained stable in 93% of the surviving animals after 100 days and in 668 after 200 days. The morphology of long-term allografts was extremely variable from minor to extensive tubular atrophy, interstitial fibrosis, glomerular hypertrophy, focal and segmental glomerulosclerosis and vascular changes. Glomerular hypertrophy occurred in uninephrectomized controls and probably denoted a response to uninephrectomy. Glomerulosclerosis increased with time and was absent in controls. Although chronic damage was evident, the rats remained tolerant to fresh donor skin. Replacement of the original kidney allograft with a fresh donor kidney resulted in 70% survival. These second grafts showed less severe renal dysfunction and morphological damage than the original allografts in the long-term follow up.  相似文献   
8.
To determine the validity of the aspirin/Reye's syndrome association, we developed an epidemiologic investigation to assess the effects of five potential sources of bias. A case-control study incorporated procedures to avoid temporal precedence and susceptibility bias. These included classifying cases as having monophasic or biphasic patterns of illness and matching for severity of symptoms at zero-time. To evaluate the effect of a potential recall bias, an "alternate-condition" control group was enrolled. A medical record review study was conducted to assess the potential for diagnostic bias, and a blanket surveillance of all hospitals in a region was conducted to evaluate reporting bias. Twenty-four case subjects and 48 matched controls were enrolled. Eight-eight percent of case subjects and only 17% of controls had received aspirin prior to the onset of Reye's syndrome (matched odds ratio, 35; 95% confidence interval, 4.2 to 288). Further analyses demonstrated that the association could not be attributed to the five potential sources of bias.  相似文献   
9.
BACKGROUND: Cysteinyl leukotrienes play a disease-regulating role in rhinosinusitis and asthma, particularly aspirin-sensitive disease. They act through 2 G-protein coupled receptors termed cysteinyl leukotriene type 1 receptor (cysLT 1 ) and cysteinyl leukotriene type 2 receptor (cysLT 2 ). We previously compared expression of cysLT 1 on mucosal leukocytes in patients with aspirin-sensitive and aspirin-tolerant rhinosinusitis. OBJECTIVE: To compare expression of cysLT 1 and cysLT 2 on leukocytes, mucus glands, and epithelium in 32 patients with chronic polypoid rhinosinusitis (21 aspirin-sensitive, 11 aspirin-tolerant) and 9 normal controls. METHODS: Total numbers of CD45 + leukocytes, percentages of these cells expressing cysLT 1 or cysLT 2 , and percentages of the total epithelial and glandular areas expressing cysLT 1 or cysLT 2 were measured in sections of nasal biopsies by using immunohistochemistry and image analysis. RESULTS: The percentages of mucosal CD45 + leukocytes expressing cysLT 1 were significantly ( P < .0001) elevated in the aspirin-sensitive but not the aspirin-tolerant patients compared with the controls. In contrast, the percentages of leukocytes expressing cysLT 2 did not differ significantly in the 3 groups. On epithelial and glandular cells, expression of cysLT 2 significantly exceeded that of cysLT 1 in both the patients with rhinosinusitis and the controls ( P < or = .004), although there was no significant difference in the expression of either receptor in the patients with rhinosinusitis (aspirin-sensitive or aspirin-tolerant) and the controls. CONCLUSION: Although cysLT 1 expression predominates on inflammatory leukocytes in patients with aspirin-sensitive rhinosinusitis, the effects of cysteinyl leukotrienes on glands and epithelium may be mediated predominantly through cysLT 2. This has potentially important therapeutic implications.  相似文献   
10.
Clustering of cardiovascular risk factors is thought to occur early in life. The endothelium is an important regulator of microvascular function. We investigated the relationship between microvascular function and cardiovascular risk factors in 145 normal, healthy children aged 11-14 years. Skin microvascular responses, measured using laser Doppler imaging, to iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP), were negatively correlated with percentage body fat ( r =−0.20, P < 0.05 and r =−0.18, P < 0.05, respectively). Subjects were stratified into quintiles based on 2-h, post-feeding glucose levels. Subjects in the upper glucose quintile (range 7.4-11.4 mmol l−1) showed significantly lower vasodilatation to both ACh (   P < 0.005  ) and SNP (   P < 0.02  ) than those in the lower quintile (range 3.9-4.9 mmol l−1). Waist-to-hip ratio and the fasting insulin resistance index were significantly greater in subjects in the upper quintile than those in the lower quintile ( P < 0.001 and P < 0.05, respectively). Additionally, in subjects in the upper glucose quintile, fasting triglyceride correlated with fasting insulin ( r = 0.59, P < 0.001) and with the fasting insulin resistance index ( r = 0.49, P < 0.009), and plasma levels of cholesterol and 2-h glucose were also correlated ( r = 0.40, P < 0.05). In a cross-section of normal children, microvascular function was negatively associated with adiposity. Additionally, in a subgroup of subjects, there was a clustering of high post-feeding glucose, impaired microvascular function, increased insulin resistance and higher central fat distribution. These findings suggest that risk factors for adult cardiovascular disease begin to cluster in normal children, which might have important consequences for development of atherosclerosis later in life.  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