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   3046篇
  免费   162篇
  国内免费   22篇
耳鼻咽喉   19篇
儿科学   63篇
妇产科学   13篇
基础医学   381篇
口腔科学   72篇
临床医学   192篇
内科学   716篇
皮肤病学   28篇
神经病学   376篇
特种医学   108篇
外科学   623篇
综合类   18篇
一般理论   1篇
预防医学   50篇
眼科学   16篇
药学   143篇
中国医学   2篇
肿瘤学   409篇
  2023年   33篇
  2022年   59篇
  2021年   116篇
  2020年   60篇
  2019年   60篇
  2018年   65篇
  2017年   61篇
  2016年   77篇
  2015年   77篇
  2014年   110篇
  2013年   120篇
  2012年   183篇
  2011年   196篇
  2010年   111篇
  2009年   101篇
  2008年   176篇
  2007年   190篇
  2006年   177篇
  2005年   192篇
  2004年   186篇
  2003年   142篇
  2002年   161篇
  2001年   50篇
  2000年   52篇
  1999年   49篇
  1998年   41篇
  1997年   45篇
  1996年   32篇
  1995年   21篇
  1994年   22篇
  1993年   14篇
  1992年   20篇
  1991年   19篇
  1990年   19篇
  1989年   22篇
  1988年   11篇
  1987年   13篇
  1986年   17篇
  1985年   14篇
  1984年   21篇
  1983年   18篇
  1982年   5篇
  1981年   11篇
  1979年   8篇
  1978年   5篇
  1977年   10篇
  1976年   6篇
  1973年   6篇
  1967年   4篇
  1966年   4篇
排序方式: 共有3230条查询结果,搜索用时 15 毫秒
81.
The purposes of this meta-analysis were (1) to examine the associations between work engagement (WE) and the personality dimensions of five-factor model and (2) to determine how much variance in WE is explained by these five factors. We performed a database search for studies related to personality traits and WE, and 36 papers that reported correlation coefficients were selected for the meta-analysis. After correcting for publication bias using the trim-and-fill method, conscientiousness had the strongest association with WE (ρ=0.41), followed by extraversion and openness to experience (0.38), neuroticism (−0.36), and agreeableness (0.27). Moreover, 30% of the WE variance could be explained by the five-factor model (R2=0.33, 95%CI=0.26–0.49) according to a path analysis using the weighted average correlation for unreliability. This proportion was higher than that from a previous meta-analysis of job satisfaction and job performance and was lower than that of personality and WE. Thus, to enhance WE, it is necessary to evaluate both the personality and the psychosocial work environment in detail.  相似文献   
82.
83.
Objective To evaluate the change in the prevalence of burnout during the COVID-19 pandemic among internists and primary care physicians in Japan, and to identify factors associated with the exacerbation of burnout among these populations during this period. Methods This was a cross-sectional study based on two web-based surveys conducted in January 2020 (before the declaration of the COVID-19 pandemic) and June 2020 (during the pandemic). The participants were internists and primary care physicians of the Japanese Chapter of the American College of Physicians. The main outcome was the change in the prevalence of burnout between before and during the “first wave” of the pandemic. We also examined factors associated with the exacerbation of burnout during this period. Results Among the 283 respondents in the first survey and 322 in the second survey, 98 (34.6%) and 111 (34.5%) reported symptoms of burnout, respectively. In June 2020, 82 respondents (25.5%) reported that their level of burnout exacerbated compared to January 2020. Only the experience of self-quarantine was associated with the exacerbation of burnout [odds ratio (OR) 3.12; 95% confidence interval (CI) 1.49-6.50; p=0.002], while being a woman, being a resident physician, and an experience of having worked in a prefecture under a state of emergency were not. Conclusions No marked change in the prevalence of burnout among internists and primary care physicians in Japan was observed during the COVID-19 pandemic as a whole. However, self-quarantine was associated with the exacerbation of the burnout level.  相似文献   
84.
Immunohistochemisty with RD3, a monoclonal antibody specific for three‐repeat (3R) tau, is sometimes hampered by diffuse neuronal staining on formalin‐fixed, paraffin‐embedded sections pretreated with formic acid and heating. Additional pretreatment with potassium permanganate followed by oxalic acid completely eliminated this diffuse RD3‐immunoreactivity (IR) in neurons. Furthermore, this additional pretreatment uniformly enhanced RD3‐IR, as well as RD4‐IR, a monoclonal antibody specific for four‐repeat (4R) tau, on pathological deposits with tau IR. This enhanced sensitivity and specificity may allow more reliable identification of 3R and 4R tau in pathological deposits, which may be variable dependent on disease and regions. Cerebral cortex and midbrain from 8 patients [5 progressive supranuclear palsy (PSP) and 3 corticobasal degeneration (CBD)] were screened for RD3‐ and RD4‐IR with this improved procedure. In addition to RD4‐positive structures found both in cerebral cortex and brainstem, RD3‐positive neurofibrillary tangles (NFTs) were also found in midbrain in 7 of these 8 cases but not in the cortex. Multi‐labeling study demonstrated that most of RD3‐negative neurons were positive for RD4. This reliable demonstration of pathological 3R tau deposits in the brainstem of PSP/CBD, so far presumably characterized by deposition of 4R tau, is useful to map tau‐positive lesions according to their biochemical composition.  相似文献   
85.
Synthesis and gas permeation measurements of several types of polymers from methylstyrene derivatives containing mono-and bis(trialkylsilyl) group(s) were carried out. Upon radical homo-and co-polymerization of silicon-containing monomers high-molecular-weight polymers were obtained. Results from gas permeation measurements showed that these types of silicon-containing polymers exhibit fairly high oxygen permselectivity (ratio of oxygen and nitrogen permeation coefficients P/P = 3,1 ? 4,6), keeping the oxygen permeation coefficients (P) in the range of between 1,4 · 10?9 and 4,5·10?9 cm3 (STP) · cm · cm?2 · s?1 · cmHg?1. From time lag measurements, it was found that permeation coefficients are dependent on the solubility of gases in the membranes rather than on diffusivity. Actually, the oxygen solubility coefficients increase with increasing silicon content in the polymers. Permselectivity of oxygen against nitrogen is governed by polymer constitution rather than by silicon content.  相似文献   
86.
BACKGROUND AND PURPOSE: Symptomatic progression is frequently observed in lacunar infarcts. The exact mechanisms of this phenomenon have not yet been clarified. SUMMARY OF CASES: We report 2 patients with lenticulostriate artery infarcts that presented with skip lesions that were restricted to gray matter. One of the patients subsequently developed symptomatic deterioration; the other experienced no further neurological events. CONCLUSIONS: A possible mechanism of differential vulnerability to ischemia of gray and white matter is considered. White matter may have a longer therapeutic time window for neuroprotective treatment than gray matter.  相似文献   
87.
88.
89.
This study aimed to investigate the levels of serum low-density lipoprotein cholesterol (LDLC) using direct measurement in healthy Japanese school children. The subjects were 621 children (325 boys and 296 girls) aged 9 to 10 in the 4th grade, and 688 children (334 boys and 354 girls) aged 12 to 13 in the 7th grade. The levels of serum LDLC and high-density lipoprotein cholesterol were measured by direct determination (Cholestest LDL and Cholestest NHDL; Daiichi Pure Chemicals Co., Ltd., Tokyo, Japan). In boys in the 4th grade, the mean, the 75th, the 90th and the 95th percentiles of LDLC levels (mg/dl) were 91.6, 104, 124 and 134, respectively. In girls in the 4th grade, they were 92.8, 108, 122 and 130. In boys in the 7th grade, they were 83.4, 96, 113 and 123. In girls in the 7th grade, they were 93.0, 106, 126 and 137. Serum LDLC levels in boys in the 7th grade were lower than those of other groups. The direct measurement of serum LDLC level is useful for evaluation of dyslipidemia in healthy school children, because the method is applicable to non-fasting serum.  相似文献   
90.
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