全文获取类型
收费全文 | 2400篇 |
免费 | 159篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 15篇 |
妇产科学 | 19篇 |
基础医学 | 415篇 |
口腔科学 | 36篇 |
临床医学 | 212篇 |
内科学 | 190篇 |
皮肤病学 | 21篇 |
神经病学 | 377篇 |
特种医学 | 93篇 |
外科学 | 118篇 |
综合类 | 222篇 |
预防医学 | 539篇 |
眼科学 | 57篇 |
药学 | 158篇 |
2篇 | |
中国医学 | 45篇 |
肿瘤学 | 50篇 |
出版年
2024年 | 4篇 |
2023年 | 30篇 |
2022年 | 90篇 |
2021年 | 121篇 |
2020年 | 84篇 |
2019年 | 71篇 |
2018年 | 75篇 |
2017年 | 68篇 |
2016年 | 79篇 |
2015年 | 86篇 |
2014年 | 101篇 |
2013年 | 205篇 |
2012年 | 117篇 |
2011年 | 136篇 |
2010年 | 100篇 |
2009年 | 116篇 |
2008年 | 128篇 |
2007年 | 121篇 |
2006年 | 107篇 |
2005年 | 118篇 |
2004年 | 78篇 |
2003年 | 70篇 |
2002年 | 58篇 |
2001年 | 39篇 |
2000年 | 40篇 |
1999年 | 25篇 |
1998年 | 35篇 |
1997年 | 32篇 |
1996年 | 26篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 22篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1974年 | 2篇 |
排序方式: 共有2589条查询结果,搜索用时 46 毫秒
1.
2.
Kuo-yi Jade Chang MHealthEc MHM BSc Lisa Lorraine Dillon MSpecEd BPsych Lil Deverell COMS PhD MEd GradDipO&M BEd Mei Ying Boon PhD BOptom FAAO Lisa Keay PhD MPH BOptom 《Clinical & experimental optometry》2020,103(4):434-448
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.
Guowei Zhang Fenger Sun Heping Liu Xiaoyan Ren Hong Xu Mingjie Wang Yizheng Fu 《Materials》2021,14(9)
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
4.
5.
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
6.
R. El Galta C. M. Van Duijn J. C. Van Houwelingen J. J. Houwing-Duistermaat 《Annals of human genetics》2005,69(4):373-381
In genetic epidemiological studies informative families are often oversampled to increase the power of a study. For a proband‐family design, where relatives of probands are sampled, we derive the score statistic to test for clustering of binary and quantitative traits within families due to genetic factors. The derived score statistic is robust to ascertainment scheme. We considered correlation due to unspecified genetic effects and/or due to sharing alleles identical by descent (IBD) at observed marker locations in a candidate region. A simulation study was carried out to study the distribution of the statistic under the null hypothesis in small data‐sets. To illustrate the score statistic, data from 33 families with type 2 diabetes mellitus (DM2) were analyzed. In addition to the binary outcome DM2 we also analyzed the quantitative outcome, body mass index (BMI). For both traits familial aggregation was highly significant. For DM2, also including IBD sharing at marker D3S3681 as a cause of correlation gave an even more significant result, which suggests the presence of a trait gene linked to this marker. We conclude that for the proband‐family design the score statistic is a powerful and robust tool for detecting clustering of outcomes. 相似文献
7.
8.
Auditory Perception and the Control of Spatially Coordinated Action of Deaf and Hearing Children 总被引:1,自引:0,他引:1
G. J. P. Savelsbergh J. B. Netelenbos H. T. A. Whiting 《Journal of child psychology and psychiatry, and allied disciplines》1991,32(3):489-500
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.
分别用聚二醇,1-2丙醇,无水乙醇与水组成不同比例的二元溶剂系统,测定了弱极性药物SMZ及TMP在上述各系统中的溶解度。从而导出药物溶解度与二混合溶剂体积分类间的半实验方程。 相似文献