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   3128篇
  免费   179篇
  国内免费   52篇
耳鼻咽喉   184篇
儿科学   42篇
妇产科学   24篇
基础医学   565篇
口腔科学   63篇
临床医学   327篇
内科学   266篇
皮肤病学   22篇
神经病学   532篇
特种医学   120篇
外科学   200篇
综合类   282篇
预防医学   454篇
眼科学   55篇
药学   125篇
  2篇
中国医学   49篇
肿瘤学   47篇
  2024年   8篇
  2023年   31篇
  2022年   100篇
  2021年   143篇
  2020年   102篇
  2019年   82篇
  2018年   101篇
  2017年   92篇
  2016年   94篇
  2015年   123篇
  2014年   130篇
  2013年   267篇
  2012年   150篇
  2011年   161篇
  2010年   133篇
  2009年   156篇
  2008年   154篇
  2007年   151篇
  2006年   146篇
  2005年   138篇
  2004年   106篇
  2003年   85篇
  2002年   71篇
  2001年   56篇
  2000年   64篇
  1999年   37篇
  1998年   46篇
  1997年   56篇
  1996年   41篇
  1995年   39篇
  1994年   20篇
  1993年   26篇
  1992年   12篇
  1991年   27篇
  1990年   17篇
  1989年   22篇
  1988年   13篇
  1987年   13篇
  1986年   9篇
  1985年   27篇
  1984年   20篇
  1983年   22篇
  1982年   11篇
  1981年   13篇
  1980年   12篇
  1979年   7篇
  1978年   6篇
  1977年   7篇
  1976年   6篇
  1968年   2篇
排序方式: 共有3359条查询结果,搜索用时 15 毫秒
1.
2.
Despite orientation and mobility (O&M) being a significant factor determining quality of life of people with low vision or blindness, there are no gold standard measures or agreement on how to measure O&M performance. In the first part of this systematic review, an inventory of O&M outcome measures used by recent studies to assess the performance of orientation and/or mobility of adults with vision impairment (low vision and blindness) is presented. A wide variety of O&M outcome measures have been implemented in different fields of study, such as epidemiologic research and interventional studies evaluating training, assistive technology, vision rehabilitation and vision restoration. The most frequent aspect of outcome measures is efficiency such as time, distance, speed and percentage of preferred walking speed, followed by obstacle contacts and avoidance, and dis/orientation and veering. Other less commonly used aspects are target identification, safety and social interaction and self-reported outcome measures. Some studies employ sophisticated equipment to capture and analyse O&M performance in a laboratory setting, while others carry out their assessment in real-world indoor or outdoor environments. In the second part of this review, the appropriateness of implementing the identified outcome measures to assess O&M performance in clinical and functional O&M practice is evaluated. Nearly a half of these outcome measures meet all four criteria of face validity (either clinical or functional), responsiveness, reliability and feasibility and have the potential to be implemented in clinical or functional O&M practice. The findings of this review confirm the complicated and dynamic nature of O&M. Multiple measures are required in any evaluation of O&M performance to facilitate holistic assessment of O&M abilities and limitations of each individual.  相似文献   
3.
4.
The structural properties, elastic anisotropy, electronic structures and work function of D022-type Al3TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al3Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D022-type Al3TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al3La is the strongest, while that of Al3Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D022-Al3Ta has an excellent strengthening effect.  相似文献   
5.
6.
Heterosexual men and homosexual men rated how arousing different sexual fantasies were and how often they had used these fantasies over the previous year. Within each group, sensual and genital same-orientation fantasies were more arousing than either public-sex or dominance-submissive fantasies, which in turn were more arousing than aggressive-sex fantasies. For both heterosexual and homosexual men the extent to which a fantasy was arousing correlated with the person's experience of the activity depicted in the fantasy. The frequency of use of a fantasy correlated positively with its arousal level but not always subtantially so. The results are discussed in the context of the mediating role of fantasy in human sexual arousal.  相似文献   
7.
具有A-π-D电子结构的苯胺衍生物掺杂的玻璃态高聚物PMMA的有机薄膜经极化取向后显示很强的二次非线性光学性能,其取向弛豫是实用化的一个有待解决的重要问题。木文通过几种苯胺衍生物以不同百分比与PMMA掺杂,用紫外-可见吸收光谱、二次谐波强度测量、动态力学粘弹谱等方法进行了取向弛豫的机理研究,结果表明分子尺寸和形状以及偶极矩的大小对取向弛豫有显著影响。  相似文献   
8.
From birth onwards, auditory stimulation directs and intensifies visual orientation behaviour. In deaf children, by definition, auditory perception cannot take place and cannot, therefore, make a contribution to visual orientation to objects approaching from outside the initial field of view. In experiment 1, a difference in catching ability is demonstrated between deaf and hearing children (10-13 years of age) when the ball approached from the periphery or from outside the field of view. No differences in catching ability between the two groups occurred when the ball approached from within the field of view. A second experiment was conducted in order to determine if differences in catching ability between deaf and hearing children could be attributed to execution of slow orientating movements and/or slow reaction time as a result of the auditory loss. The deaf children showed slower reaction times. No differences were found in movement times between deaf and hearing children. Overall, the findings suggest that a lack of auditory stimulation during development can lead to deficiencies in the coordination of actions such as catching which are both spatially and temporally constrained.  相似文献   
9.
面神经管及其定位的研究   总被引:3,自引:0,他引:3  
本文对80侧颞骨标本研究结果表明,面神经在内耳道、迷路段、水平段和垂直段的长度((?)±SD,mm)成人分别为:12.30±2.47、3.84±0.58、9.95±3.16、11.88±2.37;儿童为11.21±2.27、3.75±1.11、9.66±1.34、11.67±1.75,同时还观测了面神经管与周围结构的关系,为 Bell 面瘫减压术和面神经修补术提供了形态学依据。  相似文献   
10.
The present study assessed the effects of problem-solving (D'Zurilla & Goldfried, 1971) training on two problem-solving tasks. Sixty-one subjects were assigned randomly to and trained in one of the following groups: general orientation (GO)-problem definition (PD)-generation of alternatives (GA)-decision making (DM), GO-PD-GA, GO-PD-DM, GO-GA-DM, GO, and a control group. The six groups did not differ significantly at pretesting on the measures of selecting the best alternative solution and describing problem-solving behaviors used to solve problems. Training was significantly effective on selecting the best alternative solution for all groups compared with the control group at the time of posttesting. The GO-PD-GA-DM and GO-PD-DM groups described significantly more problem-solving behaviors than the GO-PD-GA, GO-GA-DM, and GO groups. All five treatment groups performed significantly better than the control group at the time of post-testing. At follow-up 1 month after posttesting, groups trained with the PD component selected significantly better alternatives than the groups without PD training. Groups trained with the DM component described significantly more problem-solving behaviors at follow-up than the groups trained without the DM component.  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