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   304篇
  免费   17篇
  国内免费   4篇
耳鼻咽喉   3篇
儿科学   18篇
基础医学   18篇
口腔科学   2篇
临床医学   62篇
内科学   75篇
皮肤病学   1篇
神经病学   23篇
特种医学   6篇
外科学   33篇
综合类   4篇
预防医学   31篇
眼科学   8篇
药学   33篇
中国医学   1篇
肿瘤学   7篇
  2023年   3篇
  2022年   4篇
  2021年   20篇
  2020年   2篇
  2019年   11篇
  2018年   9篇
  2017年   10篇
  2016年   7篇
  2015年   9篇
  2014年   19篇
  2013年   13篇
  2012年   16篇
  2011年   12篇
  2010年   9篇
  2009年   9篇
  2008年   10篇
  2007年   19篇
  2006年   16篇
  2005年   13篇
  2004年   10篇
  2003年   13篇
  2002年   7篇
  2001年   6篇
  2000年   7篇
  1999年   4篇
  1998年   4篇
  1996年   2篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   6篇
  1989年   3篇
  1988年   7篇
  1987年   9篇
  1986年   7篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   2篇
  1972年   3篇
排序方式: 共有325条查询结果,搜索用时 0 毫秒
131.
We analyzed brain MRI data from 372 young adult twins to identify cortical regions in which gray matter thickness and volume are influenced by genetics. This was achieved using an A/C/E structural equation model that divides the variance of these traits, at each point on the cortex, into additive genetic (A), shared (C), and unique environmental (E) components. A strong genetic influence was found in frontal and parietal regions. In addition, we correlated cortical thickness with full-scale intelligence quotient for comparison with the A/C/E maps, and several regions where cortical structure was correlated with intelligence quotient are under genetic control. These cortical measures may be useful phenotypes to narrow the search for quantitative trait loci influencing brain structure.  相似文献   
132.
A major challenge in neuroscience is finding which genes affect brain integrity, connectivity, and intellectual function. Discovering influential genes holds vast promise for neuroscience, but typical genome-wide searches assess approximately one million genetic variants one-by-one, leading to intractable false positive rates, even with vast samples of subjects. Even more intractable is the question of which genes interact and how they work together to affect brain connectivity. Here, we report a novel approach that discovers which genes contribute to brain wiring and fiber integrity at all pairs of points in a brain scan. We studied genetic correlations between thousands of points in human brain images from 472 twins and their nontwin siblings (mean age: 23.7 ± 2.1 SD years; 193 male/279 female). We combined clustering with genome-wide scanning to find brain systems with common genetic determination. We then filtered the image in a new way to boost power to find causal genes. Using network analysis, we found a network of genes that affect brain wiring in healthy young adults. Our new strategy makes it computationally more tractable to discover genes that affect brain integrity. The gene network showed small-world and scale-free topologies, suggesting efficiency in genetic interactions and resilience to network disruption. Genetic variants at hubs of the network influence intellectual performance by modulating associations between performance intelligence quotient and the integrity of major white matter tracts, such as the callosal genu and splenium, cingulum, optic radiations, and the superior longitudinal fasciculus.  相似文献   
133.
Valproate-induced hyperammonemic encephalopathy is a rare event clinically characterized by impaired sensorium, vomiting, headache, seizures and focal neurological deficits. The pathogenesis of this dreadful complication is not well understood, although hyperammonemia has been implicated in causation of encephalopathy. In this submission, we have highlighted a case of valproate-induced encephalopathy who presented mainly with bilateral cerebellar features and generalized slowing on electroencephalogram. High index of suspicion of valproate-induced hyperammonemic encephalopathy is required if diffuse ataxia is present as it is a potentially reversible clinical disorder.  相似文献   
134.
135.
136.
Objective To determine factors associated with breastfeeding in rural communities. Methods We combined qualitative and quantitative data from the Family Life Project, consisting of: (1) a longitudinal cohort study (N = 1292) of infants born September 2003–2004 and (2) a parallel ethnographic study (N = 30 families). Demographic characteristics, maternal and infant health factors, and health services were used to predict breastfeeding initiation and discontinuation using logistic and Cox regression models, respectively. Ethnographic interviews identified additional reasons for not initiating or continuing breastfeeding. Results Fifty-five percent of women initiated breastfeeding and 18% continued for at least 6 months. Maternal employment at 2 months and receiving WIC were associated with decreased breastfeeding initiation and continuation. Ethnographic data suggested that many women had never even considered breastfeeding and often discontinued breastfeeding due to discomfort, embarrassment, and lack of assistance. Conclusions Breastfeeding rates in these rural communities lag behind national averages. Opportunities for increasing breastfeeding in rural communities include enhancing workplace support, maximizing the role of WIC, increasing hospital breastfeeding assistance, and creating a social environment in which breastfeeding is normative.  相似文献   
137.
PurposePediatric gastrostomy tubes (G-tubes) are associated with frequent postoperative problems and consumption of healthcare resources. We hypothesized that a small cohort of patients disproportionately drives healthcare resource utilization after G-tube insertion. This study aimed to characterize this population in order to implement evidence-based pathways to reduce healthcare utilization after G-tube insertion.MethodsAll surgically placed pediatric G-tubes at a quaternary care center between March 2011 and June 2018 were retrospectively reviewed. Healthcare utilization including radiographic studies, emergency department (ED) visits, hospital admissions, procedures, and diagnoses was abstracted. Encounter specific charges based on CPT codes were collected. Statistical analyses were performed with Mann Whitney U, Fisher's Exact Test, and multivariate nominal logistic regression. Institutional review board approval was obtained.ResultsDuring the study period, 189 patients underwent G-tube insertion; 24% of patients presented to the ED two or more times and accounted for 82% of ED visits. This cohort of high ED utilizers was more likely to present with G-tube dislodgement [both within the first three months (early) and after three months (late)], required more radiographic studies, and accrued significantly more charges compared to low ED utilizers. Multivariate analyses demonstrated high ED utilization was significantly associated with non-Caucasian race and the surgeon performing the procedure.ConclusionsAt our institution, a significant proportion of healthcare utilization following G-tube placement is consumed by a relatively small cohort of children. Future efforts will target patients with two or more G-tube related ED visits or an early G-tube dislodgement for additional education and integration with outpatient resources.Type of studyRetrospective study.Level of evidenceLevel II.  相似文献   
138.
Abstract Background:   Proximal embolization of the splenic artery (PSAE) has recently been reported for traumatic splenic injury. The suggested mechanism of action entails a decrease in the splenic blood pressure without ischemia due to collateral blood supply. The main complications of selective embolization are continuous bleeding, splenic infarcts and splenic abscesses. The main complications of observation alone are continuous bleeding and formation of splenic pseudoaneurysms. Our aim was to assess the efficacy of PSAE in the cessation of bleeding without formation of pseudoaneurysms, and the outcome of the spleen after such intervention. Methods:   A prospective observational study of all patients undergoing PSAE for traumatic splenic injury in our institution over a 33-month period. Clinical and Doppler sonographic examinations were performed to assess cessation of bleeding, splenic blood flow, and formation of splenic pseudoaneurysms, infarcts or abscesses. Results:   During 33 months, 11 patients with blunt abdominal trauma and tomographic evidence of either high grade or actively bleeding splenic injuries were treated by PSAE. During follow-up, no patient underwent surgery or repeated embolization. Preserved blood flow was found on Doppler sonography in 82% of the patients and no pseudoaneurysms were demonstrated. A perisplenic collection was found in one patient and responded well to percutaneous drainage. Conclusions:   Proximal embolization of the splenic artery for severe splenic injury is highly successful in cessation of bleeding while preserving splenic architecture. There were minimal complications in this series demonstrated by clinical and Doppler examinations.  相似文献   
139.
A case of acute lupus pneumonitis followed by high-resolution CT   总被引:1,自引:0,他引:1  
A 43-year-old woman was admitted to our hospital because of fever and dyspnea. She had facial rash, hair-loss, arthralgia, urinary casts, thrombocytopenia, lymphocytopenia, and deposits of IgG, IgM, C3 in the epidermis. SLE was diagnosed. She also had severe dyspnea, which gradually progressed. In spite of steroid pulse therapy and cyclophosphamide, she eventually died about two months after admission. Chest X-ray film showed bilateral ground-glass shadow and volume-loss. High-resolution CT of the lung showed marked high density area with airbronchogram in the posterior part and a gradually enlarging slight high density area in the anterior area. Pathological findings of the posterior area were atelectasis and dense fibrosis. The findings of the anterior area were collapsed alveoli and dilated alveolar ducts. These findings might suggest that alveolar collapse play a major role in the course of pulmonary fibrosis of this patient.  相似文献   
140.
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