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   739篇
  免费   29篇
  国内免费   2篇
耳鼻咽喉   13篇
儿科学   15篇
妇产科学   8篇
基础医学   96篇
口腔科学   23篇
临床医学   64篇
内科学   216篇
皮肤病学   23篇
神经病学   77篇
特种医学   16篇
外科学   84篇
预防医学   55篇
眼科学   2篇
药学   27篇
肿瘤学   51篇
  2023年   1篇
  2022年   14篇
  2021年   25篇
  2020年   14篇
  2019年   24篇
  2018年   19篇
  2017年   6篇
  2016年   13篇
  2015年   25篇
  2014年   20篇
  2013年   45篇
  2012年   52篇
  2011年   55篇
  2010年   32篇
  2009年   36篇
  2008年   38篇
  2007年   41篇
  2006年   59篇
  2005年   55篇
  2004年   51篇
  2003年   42篇
  2002年   26篇
  2001年   4篇
  2000年   4篇
  1999年   4篇
  1998年   4篇
  1997年   8篇
  1996年   11篇
  1995年   5篇
  1994年   4篇
  1993年   1篇
  1992年   6篇
  1991年   3篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1985年   4篇
  1983年   2篇
  1979年   1篇
  1974年   2篇
  1973年   3篇
  1968年   2篇
排序方式: 共有770条查询结果,搜索用时 15 毫秒
1.
OBJECTIVE: To assess antipsychotic medication in the treatment of schizophrenia, based on trial drop-out rates. METHOD: The studies included were randomised controlled trials that compared any of the four clinically best-established atypical antipsychotics (quetiapine, olanzapine, risperidone or clozapine) against either of two typical antipsychotics regarded as the gold standard (haloperidol or chlorpromazine). RESULTS: Meta-analysis indicated less risk of all-cause patient withdrawal from atypical medication trials where dosage was flexible, in both the short, relative risk (RR) 0.70 (95% CI 0.64-0.76), P<0.00001, and long term, RR 0.72 (0.65-0.80), P<0.00001. Similar results were observed for withdrawal due to adverse events, RR: 0.54 (0.41-0.72), P<0.0001. Nevertheless, the favourable effects of atypical medication disappeared in trials relying on fixed dosage. CONCLUSIONS: We detected a significant positive effect in terms of the outcome of treatment discontinuation for atypical versus typical medication, though only where the use of flexible rather than fixed doses (closer to an experimental control situation) was possible.  相似文献   
2.
3.
A comparative study of an O2-diffusion cathode and a H2-diffusion anode has been performed to ascertain the limiting processes, when they are combined in a flow alkaline fuel cell with hydroperoxide ion generation. The linear sweep voltammograms and the impedance diagrams of both electrodes show large differences. The cathode reaction is charge transfer-controlled up to current densities of at least 1 A cm?2, whereas the dissociative adsorption, charge transfer and diffusion of H2 appear to limit the anode reaction. The anode, with limiting current densities of about 90 and 150 mA cm?2 for 1.0 and 6.0 M KOH, respectively, then clearly controls the hydroperoxide ion production in the fuel cell. Diffuse reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy reveal that, the carbon of the H2-diffusion anode does not undergo significant oxygen functionalisation during hydroperoxide ion generation in the fuel cell.  相似文献   
4.
OBJECTIVE   Genetic analysis is now essential for the accurate screening of families with multiple endocrine neoplasia type 2 (MEN2). We present the genetic analyses by both haplotype and direct RET proto-oncogene mutation analysis in seven Mediterranean MEN 2A families and have compared these results with biochemical screening tests and pathological examinations.
DESIGN  Total DNA was extracted from leucocytes. Linkage analysis was performed using five RFLP systems from three loci that flank the MEN2A locus (FNRB, RBP3, D10S15). RET proto-oncogene analysis was carried out by automatic DNA sequencing and adequate digestion of PCR amplified products for exons 10 and 11. Screening for medullary thyroid carcinoma or C-cell hyperplasia was performed by the pentagastrin provocation test. Adrenal medullary function was assessed by measurements of 24-hour urinary excretion of catecholamines and their metabolites. Serum calcium and phosphate measurements were the initial screen for hyperparathyroidism. Serum PTH was determined only if hyperparathyroidism was suggested by the former determinations.
PATIENT   Genetic study was performed in 59 individuals (39 at risk) from seven kindreds of Mediterranean origin with MEN 2A.
RESULTS   Diagnosis by linkage analysis was not possible in 30% of individuals at risk, but RET proto-oncogene analysis identified all these individuals. Mutations of the RET proto-oncogene were detected in exon 10 (codon 618) in one MEN 2A kindred and in exon 11 (codon 634) in the others. The results of direct analysis were concordant with linkage studies in each case. Three individuals from different MEN 2A kindreds, who were subsequently shown not to be gene carriers, had false positive pentagastrin stimulation tests.
CONCLUSION   Biochemical tests can be replaced by direct DNA mutation analysis as the first line screening test in order to identify gene carriers of MEN 2A.  相似文献   
5.
Wolfram syndrome (WS) is an autosomal recessive neurodegenerative disorder characterised by early onset diabetes mellitus and progressive optic atrophy, as well as other clinical features such as deafness, diabetes insipida, renal tract abnormalities and diverse psychiatric illnesses. A gene responsible for WS was identified in 4p16.1 (WFS1). It encodes a putative 890 amino acid transmembrane protein expressed in a wide spectrum of tissues. Recently, a new locus for WS has been located on 4q22-24, providing additional evidence for the genetic heterogeneity of this syndrome. We have studied the presence of WFS1 variants in three groups of individuals: patients with diabetes mellitus, patients with deafness and patients with both conditions. A fourth group of healthy subjects was used as control. We have identified a total of 18 nucleotide changes in the WFS1 gene: three mutations and 15 polymorphisms. Six of these changes were previously undescribed. Four of the 15 polymorphisms studied among the patients group present statistical differences in the allelic and genotypic distribution when comparing affected vs control groups.  相似文献   
6.
7.
Constitutional mutations in the RB1 gene predispose to retinoblastoma development. Hence genetic screening of retinoblastoma patients and relatives is important for genetic counseling purposes. In addition, RB1 gene mutation studies may help decipher the molecular mechanisms leading to tumors with different degrees of penetrance or expressivity. In the course of genetically screening of 107 hereditary and non-hereditary retinoblastoma patients (11 familiar bilateral, 4 familiar unilateral, 49 sporadic bilateral and 43 sporadic unilateral) and kindred from Spain, Colombia and Cuba, using direct PCR sequencing, we observed 45 distinct mutations and four RB1 deletions in 53 patients (9 familiar bilateral, 2 familiar unilateral, 31 sporadic bilateral and 11 sporadic unilateral). Most of these mutations (26/45, 57%) have not been reported before. In 32 patients, the predisposing mutations correspond to nonsense (mainly CpG transitions) and small insertions or deletions whose expected outcome is a truncated Rb protein that lacks the functional pockets and tail. Five single aminoacid replacements and seventeen mutations affecting splicing sites were also observed in retinoblastoma patients. Two of these sixteen mutations are of unclear pathogenic nature.  相似文献   
8.
The aim of this study was to compare the efficacy and tolerability of reboxetine, a uniquely selective noradrenaline reuptake inhibitor, with the selective serotonin reuptake inhibitor, fluoxetine. A double-blind, randomized, parallel-group, multicentre design was employed. One hundred and sixty-eight patients with acute major depressive episodes were randomized to receive oral reboxetine (8-10 mg/day) or oral fluoxetine (20-40 mg/day). The treatment period was 8 weeks. Reboxetine and fluoxetine were similarly effective as assessed by the mean reduction in total Hamilton Depression Rating Scale score, the percentage of responders and patients in remission, Clinical Global Impression severity of illness and global improvement scores and Montgomery-Asberg Depression Rating Scale. A sub-analysis of patients with severe depression indicated that reboxetine had superior efficacy compared with fluoxetine. Both treatments resulted in some improvement in Social Adaptation Self-evaluation Scale total scores and this was more evident for those patients treated with reboxetine who achieved remission. Both treatments were well tolerated. The results indicate that reboxetine is an effective and well tolerated antidepressant, being more effective than fluoxetine in patients with severe depression, and more effective in terms of social functioning in those patients who achieved remission.  相似文献   
9.
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