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   401篇
  免费   28篇
  国内免费   1篇
耳鼻咽喉   27篇
儿科学   8篇
妇产科学   5篇
基础医学   77篇
口腔科学   3篇
临床医学   25篇
内科学   153篇
神经病学   39篇
特种医学   6篇
外科学   23篇
综合类   1篇
一般理论   1篇
预防医学   42篇
药学   10篇
中国医学   1篇
肿瘤学   9篇
  2022年   2篇
  2021年   5篇
  2020年   8篇
  2019年   9篇
  2018年   8篇
  2017年   2篇
  2016年   7篇
  2015年   11篇
  2014年   7篇
  2013年   15篇
  2012年   21篇
  2011年   27篇
  2010年   15篇
  2009年   8篇
  2008年   34篇
  2007年   26篇
  2006年   24篇
  2005年   18篇
  2004年   23篇
  2003年   18篇
  2002年   24篇
  2001年   6篇
  2000年   4篇
  1999年   14篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1991年   3篇
  1990年   5篇
  1988年   2篇
  1987年   5篇
  1986年   5篇
  1985年   6篇
  1984年   5篇
  1982年   2篇
  1981年   2篇
  1979年   2篇
  1978年   2篇
  1977年   7篇
  1976年   3篇
  1974年   6篇
  1973年   2篇
  1972年   2篇
  1971年   4篇
  1970年   3篇
  1968年   2篇
  1967年   4篇
排序方式: 共有430条查询结果,搜索用时 46 毫秒
1.
2.
Cytogenetic analysis of peripheral lymphocytes of an infantile patient with a sacral teratoma revealed a constitutional translocation (12;15)(q13;q25) pat. The same translocation was found in four additional relatives. Loss of heterozygosity analysis of the patient's tumor material showed retention of both translocation-derived chromosomes. Since allelic loss in the 12q13 region has been observed in germ cell tumors, we hypothesize that disregulation of genes located at or near the 12q13 breakpoint may be related to the development of this sacral teratoma. As a first step towards the identification of these genes, a 12q13 genomic contig that spans the breakpoint has been constructed.  相似文献   
3.
The distribution of HLA antigen frequencies has been studied in patients with affective disorders. There were no significant differences between bipolar patients, unipolar patients, or controls. Preliminary data on HLA antigen distribution in schizophrenic patients are reported. Our negative results in affective disorders are discussed in relation to HLA studies reported from other laboratories, with special reference to some potential methodological problems.  相似文献   
4.
Differential delayed-type hypersensitivity skin testing with tuberculin purified protein derivatives from Mycobacterium bovis and M. avium is the standard for diagnosing bovine tuberculosis. However, improved tests based on defined, specific antigens are urgently needed. In the present study, a combination of bioinformatics, molecular biology, and bovine models of infection were used to screen mycobacterial proteins for their potential as diagnostic reagents which could be used in a whole-blood assay for diagnosis of tuberculosis. Initial screening of 28 proteins selected in silico and expressed as recombinants in Escherichia coli indicated that CFP-10, ESAT-6, TB27.4, TB16.2, TB15.8, and TB10.4 induced strong gamma interferon responses in experimentally infected cattle. A more thorough investigation over time in two groups of animals infected with a high (10(6) CFU) and a low (10(4) CFU) dose of M. bovis revealed that, for both groups, the strength of the in vitro response to individual antigens varied greatly over time. However, combining the results for ESAT-6, CFP-10, and TB27.4, possibly supplemented with TB10.4, gave sensitivities at different infection stages close to those obtained with M. bovis purified protein derivative. Importantly, while responsiveness to ESAT-6 and CFP-10 correlated strongly for individual samples, the same was not the case for ESAT-6 and TB27.4 responsiveness. The results suggest that combinations of specific antigens such as these have great potential in development of optimized diagnostic systems for bovine tuberculosis.  相似文献   
5.
The metalloprotease ADAM 10 is an important APP alpha-secretase candidate, but in vivo proof of this is lacking. Furthermore, invertebrate models point towards a key role of the ADAM 10 orthologues Kuzbanian and sup-17 in Notch signalling. In the mouse, this function is, however, currently attributed to ADAM 17/TACE, while the role of ADAM 10 remains unknown. We have created ADAM 10-deficient mice. They die at day 9.5 of embryogenesis with multiple defects of the developing central nervous system, somites, and cardiovascular system. In situ hybridization revealed a reduced expression of the Notch target gene hes-5 in the neural tube and an increased expression of the Notch ligand dll-1, supporting an important role for ADAM 10 in Notch signalling in the vertebrates as well. Since the early lethality precluded the establishment of primary neuronal cultures, APPs alpha generation was analyzed in embryonic fibroblasts and found to be preserved in 15 out of 17 independently generated ADAM 10-deficient fibroblast cell lines, albeit at a quantitatively more variable level than in controls, whereas a severe reduction was found in only two cases. The variability was not due to differences in genetic background or to variable expression of the alternative alpha-secretase candidates ADAM 9 and ADAM 17. These results indicate, therefore, either a regulation between ADAMs on the post-translational level or that other, not yet known, proteases are able to compensate for ADAM 10 deficiency. Thus, the observed variability, together with recent reports on tissue-specific expression patterns of ADAMs 9, 10 and 17, points to the existence of tissue-specific 'teams' of different proteases exerting alpha-secretase activity.  相似文献   
6.
A prospective, double-blind, randomized, placebo-controlled study was performed to evaluate the effect of antibiotic prophylaxis in ear surgery. The present study reports on the results of 750 patients, half of whom received cefuroxime for 1 day, the other half, placebo. All postoperative infections occurring within 2 weeks after the intervention were recorded, together with several preoperative and perioperative parameters. It is concluded that exploratory tympanoplasties (including stapedotomy) and “dry perforation” tympanoplasties should be considered “clean” operations according to the American National Research Council and do not benefit from antibiotic prophylaxis. On the other hand, tympanoplasties performed on draining ears and on ears with cholesteatoma should be considered “dirty” operations for which antibiotic prophylaxis may decrease the postoperative infection rate by factor 3. All postoperative infections healed without sequels under proper treatment, except for three that resulted in graft necrosis-one in the placebo group and two in the cefuroxime group. In consequence, prophylaxis may not be mandatory in the dirty group, although the authors advocate its use for the sake of patient and surgeon comfort.  相似文献   
7.
8.
The objective of this study was to investigate the prognostic significance of the ambulatory blood pressure (BP) during night and day and of the night-to-day BP ratio (NDR). We studied 7458 participants (mean age 56.8 years; 45.8% women) enrolled in the International Database on Ambulatory BP in relation to Cardiovascular Outcome. Using Cox models, we calculated hazard ratios (HR) adjusted for cohort and cardiovascular risk factors. Over 9.6 years (median), 983 deaths and 943 cardiovascular events occurred. Nighttime BP predicted mortality outcomes (HR, 1.18-1.24; P<0.01) independent of daytime BP. Conversely, daytime systolic (HR, 0.84; P<0.01) and diastolic BP (HR, 0.88; P<0.05) predicted only noncardiovascular mortality after adjustment for nighttime BP. Both daytime BP and nighttime BP consistently predicted all cardiovascular events (HR, 1.11-1.33; P<0.05) and stroke (HR, 1.21-1.47; P<0.01). Daytime BP lost its prognostic significance for cardiovascular events in patients on antihypertensive treatment. Adjusted for the 24-h BP, NDR predicted mortality (P<0.05), but not fatal combined with nonfatal events. Participants with systolic NDR of at least 1 compared with participants with normal NDR (> or = 0.80 to <0.90) were older, at higher risk of death, but died at higher age. The predictive accuracy of the daytime and nighttime BP and the NDR depended on the disease outcome under study. The increased mortality in patients with higher NDR probably indicates reverse causality. Our findings support recording the ambulatory BP during the whole day.  相似文献   
9.
BACKGROUND: To assess the impact of immediate versus delayed antihypertensive treatment on the outcome of older patients with isolated systolic hypertension, we extended the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) trial by an open-label follow-up study lasting 4 years. METHODS: The Syst-Eur trial included 4695 randomized patients with minimum age of 60 years and an untreated blood pressure of 160-219 mmHg systolic and below 95 mmHg diastolic. The double-blind trial ended after a median follow-up of 2.0 years (range 1-97 months). Of 4409 patients still alive, 3517 received open-label treatment consisting of nitrendipine (10-40 mg daily) with the possible addition of enalapril (5-20 mg daily), hydrochlorothiazide (12.5-25 mg daily), or both add-on drugs. Non-participants (n = 892) were also followed up. RESULTS: Median follow-up increased to 6.1 years. Systolic pressure decreased to below 150 mmHg (target level) in 2628 participants (75.0%). During the 4-year open-label follow-up, stroke and cardiovascular complications occurred at similar frequencies in patients formerly randomized to placebo and those continuing active treatment. These rates were similar to those previously observed in the active-treatment group during the double-blind trial. Considering the total follow-up of 4695 randomized patients, immediate compared with delayed antihypertensive treatment reduced the occurrence of stroke and cardiovascular complications by 28% (P = 0.01) and 15% (P = 0.03), respectively, with a similar tendency for total mortality (13%, P = 0.09). In 492 diabetic patients, the corresponding estimates of long-term benefit (P < 0.02) were 60, 51 and 38%, respectively. CONCLUSIONS: Antihypertensive treatment can achieve blood pressure control in most older patients with isolated systolic hypertension. Immediate compared with delayed treatment prevented 17 strokes or 25 major cardiovascular events per 1000 patients followed up for 6 years. These findings underscore the necessity of early treatment of isolated systolic hypertension.  相似文献   
10.
We present the nature of pathogenic SNP array findings in pregnancies without ultrasound (US) abnormalities and show the additional diagnostic value of SNP array as compared with rapid aneuploidy detection and karyotyping. 1,330 prenatal samples were investigated with a 0.5‐Mb SNP array after the exclusion of the most common aneuploidies. In 2.7% (36/1,330) of the cases, pathogenic chromosome aberrations were found; a microscopically detectable abnormality in 0.7% and a submicroscopic aberration in 2%. Our results show that in addition to the age‐ or screening‐related aneuploidy risk, in pregnancies without US abnormalities, there is a risk of 1:148 (9/1,330) for a (sub)microscopic abnormality associated with an early‐onset often severe disease, 1:222 (6/1,330) for a submicroscopic aberration causing an early‐onset disease, 1:74 (18/1,330) for carrying a susceptibility locus for a neurodevelopmental disorder, and 1:443 (3/1,330) for a late‐onset disorder (hereditary neuropathy with liability to pressure palsies in all three cases). These risk figures are important for adequate pretest counseling so that prospective parents can make informed individualized choices between targeted prenatal testing and broad testing with SNP array. Based on our results, we believe if invasive testing is performed, SNP array should be the preferred cytogenetic technique irrespective of the indication.  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