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   969篇
  免费   73篇
  国内免费   8篇
耳鼻咽喉   6篇
儿科学   25篇
妇产科学   15篇
基础医学   143篇
口腔科学   33篇
临床医学   63篇
内科学   241篇
皮肤病学   17篇
神经病学   68篇
特种医学   36篇
外科学   68篇
综合类   7篇
一般理论   2篇
预防医学   181篇
眼科学   8篇
药学   58篇
肿瘤学   79篇
  2023年   4篇
  2022年   6篇
  2021年   30篇
  2020年   13篇
  2019年   15篇
  2018年   22篇
  2017年   11篇
  2016年   31篇
  2015年   20篇
  2014年   28篇
  2013年   44篇
  2012年   83篇
  2011年   71篇
  2010年   38篇
  2009年   34篇
  2008年   61篇
  2007年   69篇
  2006年   56篇
  2005年   54篇
  2004年   62篇
  2003年   43篇
  2002年   43篇
  2001年   17篇
  2000年   21篇
  1999年   18篇
  1998年   13篇
  1997年   6篇
  1996年   8篇
  1995年   4篇
  1994年   14篇
  1993年   5篇
  1992年   6篇
  1991年   7篇
  1990年   4篇
  1989年   7篇
  1988年   7篇
  1986年   4篇
  1984年   7篇
  1983年   5篇
  1982年   4篇
  1981年   3篇
  1980年   4篇
  1979年   7篇
  1977年   5篇
  1976年   4篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1941年   2篇
  1939年   2篇
排序方式: 共有1050条查询结果,搜索用时 265 毫秒
1.
Abstract

Objective: This study aims at identifying associations between cognitive function and suicidal ideation in the sample of patients with anxiety and mood disorders (AMD).

Methods: In sum, 186 (age = 39?±?12.3 years; 142 [76.3%] females) patients with AMD were enrolled in the study. Assessment included evaluation of socio-demographic information, medication use, anxiety and depression symptoms. Cognitive tests included measures of psychomotor performance and incidental learning using the Digit Symbol Test. Trail Making Tests respectively measured perceptual speed, task-switching and executive control. Additionally, 21 patients completed tests from the Cambridge Automated Neuropsychological Test Battery measuring set shifting (Interdimensional/extradimensional set-shift), executive planning (Stockings of Cambridge), and decision making (Cambridge Gamble Task [CGT]).

Results: Almost half (45.0%, n?=?86) of the study sample patients had experienced suicidal ideations. In multivariable regression analysis, suicidal ideation was associated with a greater overall proportion of bet and risk taking on the CGT task (β?=?0.726, p?=?.010 and β?=?0.634, p?=?.019), when controlling for socio-demographic characteristics, medication use, anxiety and depression symptoms.

Conclusions: Outpatients with AMD and suicidal ideation could be distinguished by the presence of cognitive deficits in the executive function domain, particularly in impulse-control and risk taking.  相似文献   
2.
There is limited information on the relationship between parental practices that specifically discourage current cigarette smoking and adolescent cessation, and how this relationship varies by age. Among 1629 adolescent smokers, self-reported receipt of parental communication not to smoke was significantly and positively associated with readiness to quit. The strength and significance of this association decreased from early to middle adolescence and was not significant in late adolescence.  相似文献   
3.
4.
Background: The role of intraoperative fluorocholangiography (IOC) in laparoscopic cholecystectomy (LC) is controversial. We evaluated the use of IOC at an institution where the study is performed routinely. Methods: Records of all patients undergoing LC during a 3-year period ending January 1, 1996 were reviewed. Results: A total of 1207 patients received IOC, whereas 116 patients did not. IOC findings were categorized as follows: normal, 1016 cases (84%); CBD stone, 149 cases (12.3%); anomalies, 23 cases (1.9%); duodenal diverticula, 10 cases (0.8%); ductal strictures, four cases (0.3%); and CBD diverticula, 5 cases (0.4%). In the 116 patients who did not receive IOC, 35 of the procedures could not be performed, whereas 81 were not attempted. Of the 149 IOC that showed CBD stones, two were false positives. Anomalies included accessory right hepatic ducts (11 cases), cystic ducts joining the right hepatic duct (seven cases), and abnormal cystic duct entries (five cases). Duct injuries occurred in 5 cases (0.4%), three before and two after IOC. Four injuries were minor; IOC prevented CBD transection. Conclusions: Routine IOC is feasible, safe, accurate, and provides critical information of immediate use during LC. By treating ductal stones at operation and identifying patients without CBD stones, IOC minimizes need for postoperative studies, including endoscopic retrograde cholangiography (ERC).  相似文献   
5.
6.
Knowledge of the response of the primary visual cortex to the various spatial frequencies and orientations in the visual scene should help us understand the principles by which the brain recognizes patterns. Current information about the cortical layout of spatial frequency response is still incomplete because of difficulties in recording and interpreting adequate data. Here, we report results from a study of the cat primary visual cortex in which we employed a new image-analysis method that allows improved separation of signal from noise and that we used to examine the neurooptical response of the primary visual cortex to drifting sine gratings over a range of orientations and spatial frequencies. We found that (i) the optical responses to all orientations and spatial frequencies were well approximated by weighted sums of only two pairs of basis pictures, one pair for orientation and a different pair for spatial frequency; (ii) the weightings of the two pictures in each pair were approximately in quadrature (1/4 cycle apart); and (iii) our spatial frequency data revealed a cortical map that continuously assigns different optimal spatial frequency responses to different cortical locations over the entire spatial frequency range.  相似文献   
7.
Transmissible spongiform encephalopathies (TSE) are attributed to the conversion of the cellular prion protein (PrP(c)) into an abnormal isoform (PrP(sc)). This can be caused by the invasion of living organisms by infectious particles, or be inherited due to mutations on the PrP(c) gene. One of the most intriguing problems of prion biology is the inability to generate the infectious agent in vitro. This argues strongly that other cellular proteins besides those added in test tubes or found in cellular preparations are necessary for infection. Despite recent progress in the understanding of prion pathology, the subcellular compartments in which the interaction and conversion of PrP(c) into PrP(sc) take place are still controversial. PrP(c) interacts with various macromolecules at the cell membrane, in endocytic compartments and in the secretory pathway, all of which may play specific roles in the internalisation of PrP(sc) and conversion of PrP(c). A specific interacting protein required for the propagation of prions was originally proposed as a prion receptor, and later referred to as a ligand, a cofactor, protein X, or a partner. However, current studies indicate that PrP(c) associates with multi-molecular complexes, which mediate a variety of functions in distinct cellular compartments. It is proposed that a deeper understanding of the mechanics of such interactions, coupled to a better knowledge of the corresponding signalling pathways and ensuing cellular responses, will have a major impact on the prevention and treatment of TSE.  相似文献   
8.
Audit of start of anticoagulation treatment in inpatients.   总被引:4,自引:1,他引:4       下载免费PDF全文
AIMS: To develop a method for evaluating the start of anticoagulation treatment in inpatients. METHODS: One hundred case notes were audited using a proforma based on local guidelines in accordance with British Society for Haematology recommendations. RESULTS: Confirmatory investigations were done in 93% and 79% of patients with symptomatic deep venous thrombosis and pulmonary embolism, respectively. Identification of patients' risk factors for anticoagulation by history taking and laboratory tests was often inadequate: baseline coagulation screen, platelet count, liver function and renal function tests were done in 52%, 95%, 70% and 87% of cases, respectively. There was a tendency to undertreat patients: 33% of the activated partial thromboplastin times (APTT) and 58% of the International Normalised Ratios (INR) were subtherapeutic. The heparin-warfarin crossover period was particularly problematic: 37% stopped heparin without an INR that day, or had an INR of less than 2. Microscopic haematuria was monitored occasionally. Of the 62 patients continuing anticoagulation, 72% were discharged with the final INR in the therapeutic range. At discharge, only 74% of patients had documented appointments for the anticoagulant Clinic, the period between discharge and appointment ranging from 0 to 12 days. Of the 25 cases with an appointment exceeding four days after discharge, only six (24%) had arrangements for an interim INR check. CONCLUSIONS: The experience allowed the proforma to become streamlined to a more practical, reliable, and valid tool for use elsewhere. Findings will be fed back to the hospital staff to promote practice improvements before closing the audit loop by re-evaluating practice. Further studies are in progress to identify barriers experienced by doctors in implementing the guidelines and problems in the process of referral to the anticoagulant clinic.  相似文献   
9.
BACKGROUND: The analysis of epidemic influenza virus has been focused on antigenic and genomic characterization of the hemagglutinin (HA) glycoprotein in order to detect new variants for the recommendation of the vaccine strains in each season. Since October 1998, WHO organized a second meeting to evaluate the vaccine formula for the southern hemisphere. OBJECTIVES: (a) Present the antigenic and genomic characterization of influenza strains obtained from the Argentina surveillance network, (b) compare between strains collected in Argentina and other countries with the vaccine formula strains used in each season. STUDY DESIGN: Influenza strains were collected during a 5-year period (1995-1999). Initially, laboratory diagnosis was done by immunofluorescence (IF) assay on clinical samples, followed by viral isolation in Madin-Darby canine kidney (MDCK) cells. The isolates were characterized antigenically by hemagglutination-inhibition (HI) assay with post-infection ferret antisera. The genomic characterization consisted on RT-PCR followed by sequencing of the HA1 portion of the HA gene. The comparison between reference and circulating strains was analyzed by the construction of phylogenetic trees. RESULTS: The H3N2 circulating strains matched the corresponding vaccine component only in 1999, the first year when a vaccine recommended specifically for the southern hemisphere was used. Besides, H1N1 circulating strains matched the corresponding vaccine component only in 1998. Regarding to influenza B, only in 1995, the circulating strains showed no match to the B vaccine component. CONCLUSIONS: The results showed the usefulness of an intensified influenza laboratory surveillance to access the correct vaccine and the importance of having the necessary tools to characterize the circulating strains.  相似文献   
10.
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