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   3091篇
  免费   319篇
  国内免费   6篇
耳鼻咽喉   16篇
儿科学   113篇
妇产科学   45篇
基础医学   435篇
口腔科学   50篇
临床医学   454篇
内科学   497篇
皮肤病学   60篇
神经病学   203篇
特种医学   167篇
外科学   389篇
综合类   75篇
一般理论   3篇
预防医学   398篇
眼科学   11篇
药学   225篇
  2篇
肿瘤学   273篇
  2021年   45篇
  2020年   40篇
  2019年   42篇
  2018年   43篇
  2017年   45篇
  2016年   44篇
  2015年   46篇
  2014年   73篇
  2013年   98篇
  2012年   139篇
  2011年   146篇
  2010年   88篇
  2009年   83篇
  2008年   147篇
  2007年   135篇
  2006年   140篇
  2005年   136篇
  2004年   112篇
  2003年   115篇
  2002年   105篇
  2001年   102篇
  2000年   104篇
  1999年   104篇
  1998年   60篇
  1997年   50篇
  1996年   37篇
  1995年   41篇
  1994年   39篇
  1993年   30篇
  1992年   95篇
  1991年   80篇
  1990年   80篇
  1989年   89篇
  1988年   65篇
  1987年   58篇
  1986年   45篇
  1985年   48篇
  1984年   33篇
  1983年   31篇
  1982年   25篇
  1981年   19篇
  1980年   19篇
  1979年   45篇
  1978年   18篇
  1977年   28篇
  1976年   25篇
  1975年   28篇
  1974年   27篇
  1973年   24篇
  1967年   18篇
排序方式: 共有3416条查询结果,搜索用时 0 毫秒
141.
Classical Hutchinson-Gilford progeria syndrome (HGPS) is caused by LMNA mutations that generate an alternatively spliced form of lamin A, termed progerin. HGPS patients present in early childhood with atherosclerosis and striking features of accelerated aging. We report on two pedigrees of adult-onset coronary artery disease with progeroid features, who were referred to our International Registry of Werner Syndrome (WS) because of clinical features consistent with the diagnosis. No mutations were identified in the WRN gene that is responsible for WS, among these patients. Instead, we found two novel heterozygous mutations at the junction of exon 10 and intron 11 of the LMNA gene. These mutations resulted in the production of progerin at a level substantially lower than that of HGPS. Our findings indicate that LMNA mutations may result in coronary artery disease presenting in the fourth to sixth decades along with short stature and a progeroid appearance resembling WS. The absence of early-onset cataracts in this setting should suggest the diagnosis of progeroid laminopathy. This study illustrates the evolving genotype-phenotype relationship between the amount of progerin produced and the age of onset among the spectrum of restrictive dermopathy, HGPS, and atypical forms of WS.  相似文献   
142.
143.
Using a multiple‐deviant oddball paradigm, this study examined second graders' brain responses to Cantonese speech. We aimed to address the question of whether a change in a consonant or lexical tone could be automatically detected by children. We measured auditory mismatch responses to place of articulation and voice onset time (VOT), reflecting segmental perception, as well as Cantonese lexical tones including level tone and contour tone, reflecting suprasegmental perception. The data showed that robust mismatch negativities (MMNs) were elicited by all deviants in the time window of 300–500 ms in second graders. Moreover, relative to the standard stimuli, the VOT deviant elicited a robust positive mismatch response, and the level tone deviant elicited a significant MMN in the time window of 150–300 ms. The findings suggest that Hong Kong second graders were sensitive to neural discriminations of speech sounds both at the segmental and suprasegmental levels.  相似文献   
144.
The etiology for the majority of congenital heart defects (CHD) is unknown. We identified a patient with unbalanced atrioventricular septal defect (AVSD) and hypoplastic left ventricle who harbored an ~0.3 Mb monoallelic deletion on chromosome 3p14.1. The deletion encompassed the first four exons of FOXP1, a gene critical for normal heart development that represses cardiomyocyte proliferation and expression of Nkx2.5. To determine whether FOXP1 mutations are found in patients with CHD, we sequenced FOXP1 in 82 patients with AVSD or hypoplastic left heart syndrome. We discovered two patients who harbored a heterozygous c.1702C>T variant in FOXP1 that predicted a potentially deleterious substitution of a highly conserved proline (p.Pro568Ser). This variant was not found in 287 controls but is present in dbSNP at a 0.2% frequency. The orthologous murine Foxp1 p.Pro596Ser mutant protein displayed deficits in luciferase reporter assays and resulted in increased proliferation and Nkx2.5 expression in cardiomyoblasts. Our data suggest that haploinsufficiency of FOXP1 is associated with human CHD.  相似文献   
145.
Complicated skin and soft tissue infections (cSSTI) are common and frequently require treatment in hospital. Comprehensive current data on management practices in patients hospitalized with cSSTI are limited. REACH was a retrospective, observational cohort study designed to provide data on current clinical management of moderate to severe cSSTI in European hospitals. Data were collected via an electronic case report form from 129 sites in ten European countries. The study population comprised patients ≥18 years, hospitalized between March 2010 and February 2011 with cSSTI who received intravenous antibiotic treatment. Presented here is an analysis of the disease characteristics, treatment patterns during hospitalization and clinical outcomes identified by the study. The total population included 1995 patients (mean age 60.6 years; 57.7% male). Initial antibiotic treatment modification was reported in 39.6% (n = 791) of patients; it was more common in patients with co-morbidities (42.6%), those requiring surgical intervention (43.4%), those with more severe infections such as bacteraemia (51.6%) or with fascia affected (49.0%), those admitted to the intensive care unit (56.2%) and those with lesions > 50 cm2 (44.3%). A switch to narrower-spectrum antibiotic treatment (streamlining) occurred in 5.6% of patients. Mean length of hospital stay was 18.5 days (±19.9; median 12.0) and the total mortality rate was 3.4%. The data collected in REACH give a comprehensive and current view of real-life clinical management of cSSTI in European hospitals and provide evidence of a high rate of initial antibiotic treatment modification.  相似文献   
146.
Clinical aspects of pelvic inflammatory disease   总被引:2,自引:0,他引:2  
Pelvic inflammatory disease (PID) is a common and poorly managed condition. Untreated or inadequately treated, it leads to tubal infertility, ectopic pregnancy and chronic pelvic pain. Diagnostic difficulties are compounded by the wide variety of clinical presentations and the insensitivity and poor specificity of laboratory tests. Better recognition of mild and atypical disease needs a high index of suspicion whenever young, sexually active women present with gynaecological symptoms. Laparoscopy supplemented by microbiological tests and fimbrial minibiopsy should be regarded as the diagnostic 'gold standard' for research studies; new studies are required to identify techniques which might reduce under- and over-diagnosis. Early treatment reduces the risk of an adverse effect on fertility. Any therapeutic regimen selected should be effective against the common aetiological agents Chlamydia trachomatis, Neisseria gonorrhoeae, genital mycoplasmas and aerobic and anaerobic bacteria. Since at least 60% of cases of PID can be attributed to infection with a sexually transmitted organism, partner notification forms an essential part of management.   相似文献   
147.
Appendiceal intussusception is a rare entity. The majority of cases reported in the literature address surgical and colonoscopic approaches to treatment of the condition. The existing radiologic literature largely describes the sonographic and double-contrast enema findings of appendiceal intussusception. We present a case of appendiceal intussusception and describe the air-contrast enema, sonographic and CT findings.  相似文献   
148.
Mechanical efficiency during repetitive vertical jumping   总被引:1,自引:0,他引:1  
The purpose of this study was to compare mechanical efficiency between repeated static jumps (SJ), countermovement jumps (CMJ), drop jumps from 75% of maximum CMJ jump height (75DJ) and drop jumps from 125% of maximum CMJ height (125DJ). Subjects included eight jump-trained males. All subjects completed 30 continuous repetitions in the SJ, CMJ, 75DJ, and 125DJ. Oxygen consumption, peak force and center of mass displacement for each repetition during the four jumping patterns were measured. ME was calculated from a combination of force-time curves, displacement-time curves and lactate-corrected oxygen consumption values. In addition, muscle activity was recorded from the vastus medialis, vastus lateralis and biceps femoris using surface electromyography (EMG). 125DJ and 75DJ resulted in significantly (P ≤ 0.05) greater ME in comparison to CMJ and SJ. CMJ resulted in significantly greater ME in comparison to SJ. In addition, braking phase muscle activity was significantly greater in 125DJ and 75DJ in comparison to CMJ. Negative work was significantly different between 125DJ, 75DJ and CMJ (125DJ > 75DJ > CMJ). There was a significant positive correlation (r = 0.68) between ME and negative work performed across 125DJ, 75DJ and CMJ. These findings suggest that stretch-shortening cycle movements, which include a strenuous braking phase combined with simultaneous high muscle activity, increase ME. This may be due to optimal muscle-tendon unit kinetics and usage of stored elastic energy.  相似文献   
149.
150.
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