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   2821篇
  免费   148篇
  国内免费   18篇
耳鼻咽喉   15篇
儿科学   46篇
妇产科学   55篇
基础医学   364篇
口腔科学   49篇
临床医学   245篇
内科学   576篇
皮肤病学   42篇
神经病学   274篇
特种医学   99篇
外科学   572篇
综合类   9篇
预防医学   160篇
眼科学   14篇
药学   170篇
中国医学   3篇
肿瘤学   294篇
  2023年   15篇
  2022年   22篇
  2021年   50篇
  2020年   33篇
  2019年   54篇
  2018年   53篇
  2017年   40篇
  2016年   55篇
  2015年   52篇
  2014年   73篇
  2013年   131篇
  2012年   192篇
  2011年   206篇
  2010年   112篇
  2009年   111篇
  2008年   182篇
  2007年   211篇
  2006年   187篇
  2005年   178篇
  2004年   149篇
  2003年   143篇
  2002年   135篇
  2001年   65篇
  2000年   60篇
  1999年   69篇
  1998年   26篇
  1997年   22篇
  1996年   20篇
  1995年   11篇
  1994年   23篇
  1993年   12篇
  1992年   23篇
  1991年   8篇
  1990年   29篇
  1989年   20篇
  1988年   21篇
  1987年   9篇
  1986年   22篇
  1985年   10篇
  1984年   14篇
  1983年   8篇
  1982年   12篇
  1980年   12篇
  1979年   7篇
  1975年   7篇
  1974年   9篇
  1973年   10篇
  1972年   15篇
  1967年   6篇
  1965年   9篇
排序方式: 共有2987条查询结果,搜索用时 46 毫秒
61.
Beckwith–Wiedemann syndrome (BWS) is an imprinting disorder associating macroglossia, abdominal wall defects, visceromegaly, and a high risk of childhood tumor. Molecular anomalies are mostly epigenetic; however, mutations of CDKN1C are implicated in 8% of cases, including both sporadic and familial forms. We aimed to describe the phenotype of BWS patients with CDKN1C mutations and develop a functional test for CDKN1C mutations. For each propositus, we sequenced the three exons and intron–exon boundaries of CDKN1C in patients presenting a BWS phenotype, including abdominal wall defects, without 11p15 methylation defects. We developed a functional test based on flow cytometry. We identified 37 mutations in 38 pedigrees (50 patients and seven fetuses). Analysis of parental samples when available showed that all mutations tested but one was inherited from the mother. The four missense mutations led to a less severe phenotype (lower frequency of exomphalos) than the other 33 mutations. The following four tumors occurred: one neuroblastoma, one ganglioneuroblastoma, one melanoma, and one acute lymphoid leukemia. Cases of BWS caused by CDKN1C mutations are not rare. CDKN1C sequencing should be performed for BWS patients presenting with abdominal wall defects or cleft palate without 11p15 methylation defects or body asymmetry, or in familial cases of BWS.  相似文献   
62.
Binge-eating disorder is characterized by excessive, uncontrollable consumption of palatable food within brief periods of time. The role of the glutamatergic N-methyl-D-aspartate (NMDA) receptor system in hedonic feeding is poorly understood. The aim of this study was to characterize the effects of the uncompetitive NMDA receptor antagonist memantine on palatable food-induced behavioral adaptations using a rat model, which mimics the characteristic symptomatology observed in binge-eating disorder. For this purpose, we allowed male Wistar rats to respond to obtain a highly palatable, sugary diet (Palatable group) or a regular chow diet (Chow control group), for 1 h a day, under a fixed-ratio 1 (FR1) schedule of reinforcement. Upon stabilization of food responding, we tested the effects of memantine on the Chow and Palatable food groups'' intake. Then, we tested the effects of memantine on food-seeking behavior, under a second-order schedule of reinforcement. Furthermore, we investigated the effects of memantine on the intake of food when it was offered in an aversive, bright compartment of a light/dark conflict test. Finally, we evaluated the effects of memantine on FR1 responding for food, when microinfused into the nucleus accumbens (NAcc) shell or core. Memantine dose-dependently decreased binge-like eating and fully blocked food-seeking behavior and compulsive eating, selectively in the Palatable food group. The drug treatment did not affect performance of the control Chow food group. Finally, intra-NAcc shell, but not core, microinfusion of memantine decreased binge-like eating. Together, these findings substantiate a role of memantine as a potential pharmacological treatment for binge-eating disorder.  相似文献   
63.
Clinical evaluation of 33 male patients affected by multiple symmetric lipomatosis has revealed a previously unreported high prevalence of somatic and autonomic neuropathies. In 84% of the patients, clinical examination revealed signs or symptoms of neural disturbances, ranging from a vibratory sensory loss to severely incapacitating trophic ulcers or Charcot's arthropathy. Electrodiagnostic investigations demonstrated a significant reduction of motor and sensory conduction velocity in the peroneal and sural nerves. Morphometric studies of nerve and muscle biopsies from five patients with multiple symmetric lipomatosis revealed a significant reduction in myelinated fiber density (4435 +/- 593 fibers/mm2 in MSL vs 7660 +/- 800 in controls; p less than 0.05), a selective reduction in the large fibers of 7 to 10 micron in diameter, and signs of chronic denervation-reinnervation processes. Bedside tests for autonomic neuropathy were abnormal in 15 of 20 patients studied. Metabolic studies in these patients confirmed a significant increase in plasma high-density lipoprotein fractions consistent with the diagnosis of hyperalphalipoproteinemia, and a significant reduction in plasma low-density lipoprotein fractions (hypobetalipoproteinemia) associated with a marked enhancement of lipoprotein lipase activity in adipose tissue. Thus, a metabolic factor has to be considered in the pathogenesis of MSL neuropathy.  相似文献   
64.
65.
66.
67.
Conservative surgery for early cancer of the distal rectum   总被引:6,自引:5,他引:6  
From 1967 through 1988, 36 patients underwent local excision of a distal rectal cancer as an initial operative procedure with curative intent. A diagnostic, preoperative protocol was performed to assess the histologic grade of the tumor, the depth of penetration in the rectal wall, and the presence of positive lymph nodes or distant metastases. All patients had a transanal local excision performed under general anesthesia. If preoperative criteria were not confirmed by histopathologic specimen examination, a major operation was advised. To increase the chance of local control, external adjuvant radiotherapy was used in T2 cancers. Postoperative mortality was 0 percent. The postoperative complication rate was 9.3 percent. The observed local recurrence rate was 3 percent, and the rectal cancer-specific death rate was 6 percent. We compared these results with those obtained in 70 concomitant patients operated on by us employing a traditional resection for Dukes' A rectal cancer. There are no statistically significant differences between groups. In light of our findings, a policy of curative local excision is justified in accurately selected cases of distal rectal cancer.  相似文献   
68.
BackgroundThe doubling of the number of people with dementia in the coming decades coupled with the rapid decline in the working population in our graying society is expected to result in a large decrease in the number of professionals available to provide care to people with dementia. As a result, care will be supplied increasingly by untrained informal caregivers and volunteers. To promote effective care and avoid overburdening of untrained and trained caregivers, they must become properly skilled. To this end, the European Skills Training and Reskilling (STAR) project, which comprised experts from the domains of education, technology, and dementia care from 6 countries (the Netherlands, Sweden, Italy, Malta, Romania, and the United Kingdom), worked together to create and evaluate a multilingual e-learning tool. The STAR training portal provides dementia care training both for informal and formal caregivers.ObjectiveThe objective of the current study was to evaluate the user friendliness, usefulness, and impact of STAR with informal caregivers, volunteers, and professional caregivers.MethodsFor 2 to 4 months, the experimental group had access to the STAR training portal, a Web-based portal consisting of 8 modules, 2 of which had a basic level and 6 additional modules at intermediate and advanced levels. The experimental group also had access to online peer and expert communities for support and information exchange. The control group received free access to STAR after the research had ended. The STAR training portal was evaluated in a randomized controlled trial among informal caregivers and volunteers in addition to professional caregivers (N=142) in the Netherlands and the United Kingdom. Assessments were performed with self-assessed, online, standardized questionnaires at baseline and after 2 to 4 months. Primary outcome measures were user friendliness, usefulness, and impact of STAR on knowledge, attitudes, and approaches of caregivers regarding dementia. Secondary outcome measures were empathy, quality of life, burden, and caregivers’ sense of competence.ResultsSTAR was rated positively by all user groups on both usefulness and user friendliness. Significant effects were found on a person-centered care approach and on the total score on positive attitudes to dementia; both the experimental and the control group increased in score. Regarding empathy, significant improvements were found in the STAR training group on distress, empathic concern, and taking the perspective of the person with dementia. In the experimental group, however, there was a significant reduction in self-reported sense of competence.ConclusionsThe STAR training portal is a useful and user-friendly e-learning method, which has demonstrated its ability to provide significant positive effects on caregiver attitudes and empathy.  相似文献   
69.
70.
ObjectivesAdequate hepatic arterial (HA) flow to the bile duct is essential in liver transplantation. This study was conducted to determine if the ratio of directly measured HA flow to weight is related to the occurrence of biliary complications after deceased donor liver transplantation.MethodsA retrospective review of 2684 liver transplants carried out over a 25-year period was performed using data sourced from a prospectively maintained database. Rates of biliary complications (biliary leaks, anastomotic and non-anastomotic strictures) were compared between two groups of patients with HA flow by body weight of, respectively, <5 ml/min/kg (n = 884) and ≥5 ml/min/kg (n = 1800).ResultsPatients with a lower ratio of HA flow to weight had higher body weight (92 kg versus 76 kg; P < 0.001) and lower HA flow (350 ml/min versus 550 ml/min; P < 0.001). A lower ratio of HA flow to weight was associated with higher rates of biliary complications at 2 months, 6 months and 12 months (19.8%, 28.2% and 31.9% versus 14.8%, 22.4% and 25.8%, respectively; P < 0.001).ConclusionsA ratio of HA flow to weight of < 5 ml/min/kg is associated with higher rates of biliary complications. This ratio may be a useful parameter for application in the prevention and early detection of biliary complications.  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