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   2590066篇
  免费   184708篇
  国内免费   7568篇
耳鼻咽喉   34283篇
儿科学   85259篇
妇产科学   71611篇
基础医学   363766篇
口腔科学   69699篇
临床医学   234804篇
内科学   515860篇
皮肤病学   62473篇
神经病学   213670篇
特种医学   99981篇
外国民族医学   736篇
外科学   386641篇
综合类   50447篇
现状与发展   5篇
一般理论   970篇
预防医学   196491篇
眼科学   56746篇
药学   188107篇
  8篇
中国医学   5332篇
肿瘤学   145453篇
  2021年   20008篇
  2019年   20648篇
  2018年   29334篇
  2017年   22631篇
  2016年   26266篇
  2015年   29537篇
  2014年   40485篇
  2013年   60513篇
  2012年   80342篇
  2011年   84602篇
  2010年   51076篇
  2009年   49191篇
  2008年   79121篇
  2007年   83920篇
  2006年   85675篇
  2005年   81847篇
  2004年   78833篇
  2003年   76158篇
  2002年   73437篇
  2001年   128469篇
  2000年   131383篇
  1999年   110542篇
  1998年   31281篇
  1997年   27944篇
  1996年   28247篇
  1995年   27403篇
  1994年   25089篇
  1993年   23439篇
  1992年   85202篇
  1991年   81606篇
  1990年   78831篇
  1989年   76093篇
  1988年   69515篇
  1987年   68028篇
  1986年   63560篇
  1985年   60537篇
  1984年   44967篇
  1983年   37971篇
  1982年   22467篇
  1981年   19996篇
  1979年   38971篇
  1978年   27455篇
  1977年   23268篇
  1976年   21512篇
  1975年   22830篇
  1974年   26801篇
  1973年   25390篇
  1972年   23763篇
  1971年   21966篇
  1970年   20188篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
Children who expect they can bring about good outcomes and avoid bad outcomes tend to experience more personal successes. Little is known about factors that contribute to these ‘control expectancies’. The purpose of the present study was to determine whether children's internal control expectancies occur in the context of parents’ internal control expectancies, low family strain, and high family cohesiveness and whether these factors are more strongly related to daughters’ than sons’ control expectancies. A community sample of 85 children aged 9–11 years and their parents (85 mothers; 63 fathers) completed rating scales. Fathers’ more internal control expectancies and mothers’ reports of fewer family strains were associated with daughters’ but not sons’ greater internal control expectancies, and greater family cohesiveness was related to both daughters’ and sons’ internal control orientations. These findings suggest that family factors may contribute to children's, particularly daughters’, development of internal control expectancies.  相似文献   
66.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  相似文献   
67.
68.
In the 6th Basic Plan for Long-Term Electricity Supply and Demand (6th BPE) for Korea, for the first time, the environmental costs of air pollution caused by oxides of sulfur (SOx), oxides of nitrogen (NOx), and particulate matters (PM) from power plants were estimated and included. However, several deficiencies in evaluating the environmental costs were found. In this study, (1) the validity of the environmental costs used in the 6th BPE was assessed, (2) a systematic approach was suggested and used to improve the environmental costs estimation, and (3) the sensitivity of the cost of generating electricity to the environmental costs by fuel type with the proposed approach was discussed. We found that the applied environmental costs used in the 6th BPE did not fully include the demographic characteristics of Korea. By applying more realistic parameter values, it was found that the newly estimated environmental cost was about 23 times higher than the cost estimated in the original 6th BPE for coal-fired power plants and about 1.5 times higher for liquefied natural gas (LNG)-fired power plants, suggesting that LNG-fired power plants are more economical if using more realistic environmental costs. Thus, it is critical to check the validity of parameter values when calculating environmental costs.  相似文献   
69.
70.
We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous‐wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end‐hole catheter was required to determine the subvalvular and valvular components of the obstruction.  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