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   1093篇
  免费   59篇
  国内免费   3篇
耳鼻咽喉   2篇
儿科学   48篇
妇产科学   13篇
基础医学   84篇
口腔科学   80篇
临床医学   75篇
内科学   346篇
皮肤病学   10篇
神经病学   169篇
特种医学   33篇
外科学   111篇
综合类   30篇
一般理论   1篇
预防医学   34篇
眼科学   8篇
药学   68篇
中国医学   1篇
肿瘤学   42篇
  2023年   5篇
  2022年   13篇
  2021年   41篇
  2020年   26篇
  2019年   35篇
  2018年   47篇
  2017年   28篇
  2016年   16篇
  2015年   22篇
  2014年   35篇
  2013年   58篇
  2012年   89篇
  2011年   95篇
  2010年   54篇
  2009年   58篇
  2008年   78篇
  2007年   88篇
  2006年   54篇
  2005年   71篇
  2004年   77篇
  2003年   52篇
  2002年   56篇
  2001年   7篇
  2000年   4篇
  1999年   8篇
  1998年   7篇
  1997年   5篇
  1996年   5篇
  1995年   2篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1984年   3篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
  1970年   1篇
排序方式: 共有1155条查询结果,搜索用时 187 毫秒
61.
PURPOSE: A lack of selective alpha1-adrenergic receptor (alpha1-ARs) agonists and antagonists has made it difficult to clarify the precise function of these receptors in the CNS. We recently generated transgenic mice that overexpress either wild-type or a constitutively active mutant alpha 1B-AR in tissues that normally express the receptor. Both wild-type and mutant mice showed an age-progressive neurodegeneration with locomotor impairment and probable stress-induced motor events, which can be partially reversed by alpha 1-AR antagonists. We hypothesized that the wild-type and mutant mice may exhibit spontaneous epileptogenicity as compared with normal (nontransgenic) mice. METHODS: Normal, wild-type, and mutant mice were studied. Twenty mice (1 year old) underwent prolonged video-EEG monitoring over a 4-week period. Raw EEG data were blindly analyzed by visual inspection for the presence of interictal and ictal epileptic activities. RESULTS: During the acute postoperative period (< or = 3 days), both wild-type (26.1 +/- 8.07 spikes/day) and mutant mice (116.87 +/- 55.13) exhibited more frequent interictal spikes than did normal mice (2.17 +/- 0.75; p value, <0.05), but all three groups showed EEG and clinical seizures. During the later monitoring periods (>3 days), wild-type and mutant mice showed more frequent interictal spikes (15.44 +/- 4.07; p < 0.01; and 6.05 +/- 2.46; p < 0.05, respectively) as compared with normal mice (0.41 +/- 0.41), but only mutant mice had spontaneous clinical seizures (means +/- SEM). CONCLUSIONS: The selective overexpression of the alpha 1B-AR is associated with increased in vivo spontaneous interictal epileptogenicity and EEG/behavioral seizures. These results suggest a possible role (direct or indirect) for the alpha 1B-ARs in the development and expression of epileptogenicity.  相似文献   
62.
63.
An attempt was made to assess noninvasively the patency of aorto-coronary bypass grafts by two-dimensional echocardiography (2-D echo) in 21 patients who underwent myocardial revascularization. Fifteen patients had one graft while the other six had two grafts. All 21 patients underwent angiography 6–18 months after operation. A day before angiography a 2-D echo was performed with the aim of visualizing the bypass grafts. In 18 patients with 23 grafts (13 with 1 graft and 5 with 2 grafts) it was possible to visualize the tract of the graft, by 2-D echo; 16 were judged patent on 2-D echo and confirmed by selective angiography, while 5 grafts were considered occluded both on 2-D echo and angiography. The other 2 grafts were considered to be occluded on 2-D echo but angiographic control displayed their patency. In 3 patients 2-D echo failed to visualize grafts that were patent angiographically. These data must be considered preliminary and need validation in a larger number of patients. However it is reasonable to conclude that 2-D echo has a reliable capacity to predict graft patency. Such an application may be of value in sequential control of patients with aorto-coronary bypass surgery, especially when combined with other clinical and/or technical data.  相似文献   
64.
Laparoscopic ligation of the deep and superficial inferior epigastric vessels was done for ten mastectomized patients who elected to have autogenous reconstruction of their breast. All these patients had at least one indication for the delay which included obesity, smoking, or requirement of a large volume of tissue for their reconstruction. The procedure did not add any morbidity or mortality to our patients and was found to be comparable to the “open” delay in preventing partial tissue loss in all but two patients. We describe the use of a minimally invasive procedure to augment the deep superior epigastric pedicled blood supply for the future transverse rectus abdominus flap. We have found in laparoscopic delay a safe, short procedure that is useful in high risk patients who choose the option of autologous breast reconstruction.  相似文献   
65.
66.
Pediatric short bowel syndrome: redefining predictors of success   总被引:2,自引:0,他引:2       下载免费PDF全文
OBJECTIVE: To determine predictors of survival and of weaning off parenteral nutrition (PN) in pediatric short bowel syndrome (SBS) patients. SUMMARY BACKGROUND DATA: Pediatric SBS carries extensive morbidity and high mortality, but factors believed to predict survival or weaning from PN have been based on limited studies. This study reviews outcomes of a large number of SBS infants and identifies predictors of success. METHODS: Multivariate Cox proportional hazards analysis was conducted on 80 pediatric SBS patients. Primary outcome was survival; secondary outcome was ability to wean off PN. Nonsignificant covariates were eliminated. P < 0.05 was considered significant. RESULTS: Over a mean of 5.1 years of follow-up, survival was 58 of 80 (72.5%) and 51 weaned off PN (63.8%). Cholestasis (conjugated bilirubin > or =2.5 mg/dL) was the strongest predictor of mortality (relative risk [RR] 22.7, P = 0.005). Although absolute small bowel length was only slightly predictive, percentage of normal bowel length (for a given infant's gestational age) was strongly predictive of mortality (if <10% of normal length, RR of death was 5.7, P = 0.003) and of weaning PN (if > or =10% of normal, RR of weaning PN was 11.8, P = 0.001). Presence of the ileocecal valve (ICV) also strongly predicted weaning PN (RR 3.9, P < 0.0005); however, ICV was not predictive of survival. CONCLUSIONS: Cholestasis and age-adjusted small bowel length are the major predictors of mortality in pediatric SBS. Age-adjusted small bowel length and ICV are the major predictors of weaning from PN. These data permit better prediction of outcomes of pediatric SBS, which may help to direct future management of these challenging patients.  相似文献   
67.
Context  Limited data exist regarding population-based epidemiologic changes in incidence of infective endocarditis (IE). Objective  To evaluate temporal trends in the incidence and clinical characteristics of IE. Design, Setting, and Patients  Population-based survey using the resources of the Rochester Epidemiology Project of Olmsted County, Minnesota. One hundred seven IE episodes occurred in 102 Olmsted County residents between 1970 and 2000. The modified Duke criteria were used to validate the diagnosis of definite or possible IE. Main Outcome Measures  Incidence of IE, proportion of patients with underlying heart disease, and causative microorganisms and clinical characteristics. Results  Age- and sex-adjusted incidence of IE ranged from 5.0 to 7.0 cases per 100 000 person-years during the study period and did not change significantly over time (P = .42 for trend). Infective endocarditis caused by viridans group streptococci was the most common organism-specific subgroup, with an annual adjusted incidence of 1.7 to 3.5 cases per 100 000; in comparison, IE due to Staphylococcus aureus had an annual adjusted incidence of 1.0 to 2.2 cases per 100 000. No time trend was detected for either pathogen group (P = .63 and P = .66, respectively). An increasing temporal trend was observed in the proportions of prosthetic valve IE cases (P = .09). Among people with underlying heart disease, there was an increasing temporal trend in mitral valve prolapse (P = .04) and a decreasing trend in rheumatic heart disease (P = .08). However, the absolute numbers were small. There was no time trend in rates of valve surgery or 6-month mortality during the study period (P = .97 and P = .59, respectively). Conclusions  In this community-based temporal trend study, we found no substantial change in the incidence of IE over the past 3 decades. Viridans group streptococci continue to outnumber S aureus as the most common causative organisms of IE in this population.   相似文献   
68.
BACKGROUND AND PURPOSE: To assess the long-term acceptance of non-invasive nasal continuous positive air pressure (CPAP) in multiple system atrophy (MSA) patients with polysomnographic (PSG)-confirmed sleep apneas and/or nocturnal stridor. PATIENTS AND METHODS: Sleep-related breathing disorders were investigated by PSG in 22 MSA patients in whom stridor and sleep-related respiratory disturbances were clinically suspected. Patients in whom the first PSG disclosed either a sleep apnea/hypopnea index (AHI)> or =10 or stridor with or without apneas underwent a second PSG for CPAP titration. RESULTS: Three patients presented with an obstructive sleep apnea syndrome without stridor, whereas 15 patients presented stridor occurring alone or accompanied by apneas. Twelve patients pursued CPAP. Two severely disabled patients died a few days after CPAP initiation, and five discontinued CPAP because of discomfort. One patient died after 17 months of follow-up. Since the onset of CPAP, the four remaining patients reported more efficacious sleep and improved daytime alertness. These patients had significantly less severe disease at the time of CPAP initiation. Age, disease duration, the presence of sleep complaints, excessive daytime somnolence (EDS) and AHI did not account for CPAP compliance. CONCLUSION: The severity of motor impairment at the initiation of treatment appears to be the most significant limiting factor for CPAP long-term acceptance.  相似文献   
69.
70.
Recurrent epistaxis is a common pediatric problem with uncertain etiology in most cases. We observed frequent complaints, or history of epistaxis in children with migraine. The aim of this study was to determine whether there is an association between epistaxis and migraine in children. A detailed questionnaire was used to conduct a study of 45 consecutive patients, ages 6-11 years, with migraine, diagnosed according to the 1997 proposed pediatric revisions to the International Headache Society criteria; the patients were evaluated in our Pediatric Neurology Clinic. Control subjects consisted of 64 children without recurrent headaches, matched as a group for age and sex, and drawn as a convenient sample from two general pediatric practices and an elementary school. Sixteen (36%) of 45 patients with migraine had epistaxis as compared with 7 (11%) of 64 control subjects (odds ratio = 4.5; 95% confidence interval 1.6-12.1; P = 0.002). Epistaxis began an average of 3 years before migraine with similar characteristics to idiopathic epistaxis in habitual nose-bleeders, such as onset in early childhood, high incidence in sleep, and family history of epistaxis. This study demonstrates a significant association between migraine and recurrent epistaxis in children. Recurrent epistaxis increased the odds of migraine more than fourfold. Moreover, these data raise the question of whether epistaxis may represent a precursor to childhood migraine. The two disorders may share a common pathogenesis, and a prospective, longitudinal study is required to define further the relationship between them.  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