全文获取类型
收费全文 | 1396696篇 |
免费 | 98667篇 |
国内免费 | 3062篇 |
专业分类
耳鼻咽喉 | 20471篇 |
儿科学 | 41991篇 |
妇产科学 | 40093篇 |
基础医学 | 197166篇 |
口腔科学 | 41439篇 |
临床医学 | 118559篇 |
内科学 | 274048篇 |
皮肤病学 | 31159篇 |
神经病学 | 112201篇 |
特种医学 | 56282篇 |
外国民族医学 | 476篇 |
外科学 | 215684篇 |
综合类 | 31515篇 |
现状与发展 | 6篇 |
一般理论 | 511篇 |
预防医学 | 97439篇 |
眼科学 | 32517篇 |
药学 | 104381篇 |
4篇 | |
中国医学 | 3132篇 |
肿瘤学 | 79351篇 |
出版年
2018年 | 12964篇 |
2016年 | 11583篇 |
2015年 | 13088篇 |
2014年 | 18187篇 |
2013年 | 27668篇 |
2012年 | 36235篇 |
2011年 | 38221篇 |
2010年 | 22961篇 |
2009年 | 22207篇 |
2008年 | 36549篇 |
2007年 | 39743篇 |
2006年 | 40266篇 |
2005年 | 38899篇 |
2004年 | 37859篇 |
2003年 | 36593篇 |
2002年 | 36052篇 |
2001年 | 65416篇 |
2000年 | 67139篇 |
1999年 | 57055篇 |
1998年 | 15483篇 |
1997年 | 14094篇 |
1996年 | 13546篇 |
1995年 | 12818篇 |
1994年 | 11968篇 |
1992年 | 43904篇 |
1991年 | 42379篇 |
1990年 | 41603篇 |
1989年 | 40605篇 |
1988年 | 37848篇 |
1987年 | 37283篇 |
1986年 | 35749篇 |
1985年 | 33884篇 |
1984年 | 25366篇 |
1983年 | 21592篇 |
1982年 | 13029篇 |
1981年 | 11918篇 |
1979年 | 24419篇 |
1978年 | 17369篇 |
1977年 | 15112篇 |
1976年 | 13622篇 |
1975年 | 15585篇 |
1974年 | 18417篇 |
1973年 | 17838篇 |
1972年 | 17087篇 |
1971年 | 15958篇 |
1970年 | 15131篇 |
1969年 | 14528篇 |
1968年 | 13598篇 |
1967年 | 12168篇 |
1966年 | 11443篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
T H Bourne D Jurkovic J Waterstone S Campbell W P Collins 《Ultrasound in obstetrics & gynecology》1991,1(1):53-59
Transvaginal ultrasonography with color flow mapping has been used to study changes in intrafollicular blood flow and morphology during follicular rupture and presumed ovulation in one human volunteer. Detailed monitoring started on day 11 of the menstrual cycle and the follicle began to rupture at 14.30 on day 13. This event was preceded by a defined rise and peak in the level of immunoreactive serum luteinizing hormone (LH) by 42 h and 17 h 20 min, respectively. Blood vessels were clearly visible in the inner ring of the follicle (the granulosa layer) at the time of the LH peak and part of the granulosa (probably containing the oocyte) started to detach before the follicle ruptured. The maximum value for the peak blood velocity in the inner vessels was observed 10 s after the start of follicular rupture and there was a concurrent increase in the impedance to blood flow, as reflected by the resistance index and the pulsatility index. The follicle took 14 min 29 s to empty and the corpus haemorrhagicum started to form about 1 min later. These preliminary data suggest that intrafollicular angiogenesis and changes in blood flow can be monitored by a relatively non-invasive technique. Changes in vascularity might be used to predict imminent ovulation and could possibly be identified or modified biochemically to help achieve or avoid a pregnancy. 相似文献
992.
M G Van Luijtelaar F G Wouterlood J A Tonnaer H W Steinbusch 《Synapse (New York, N.Y.)》1991,8(3):162-168
Degeneration of neurons in the central nervous system is associated with morphological changes. Previous observations made at the light microscopical level indicated degeneration of serotonin-immunoreactive (IR) fibers in the aged rat brain. In this study, a comparison at the ultrastructural level was made between serotonin-IR normal thin and aberrant swollen varicose fibers in the caudate-putamen complex of the aged rat. Ultrastructural features such as the size and content of the thin varicose fibers resembled those in the caudate-putamen complex of the young rat as reported by others. The aberrant profiles were swollen, reaching a size of 6 microns. Their vesicles varied in size and were no longer uniformly round. Moreover, distorted mitochondria and membrane-filled vacuolelike structures were a common feature of the aberrant profiles. These changes are indicative of a degenerative process and give further evidence that, whereas many serotonergic fibers are preserved at high age, other serotonergic fibers are degenerating in the caudate-putamen complex of the aged rat. 相似文献
993.
VISUOMOTOR PERFORMANCE OF NORMAL AND CLUMSY CHILDREN. II: ARM-TRACKING WITH AND WITHOUT VISUAL FEEDBACK 总被引:2,自引:2,他引:0
J. H. P. van der Meulen J. J. Denier van der Gon C. C. A. M. Gielen R. H. J. M. Gooskens J. Willemse 《Developmental medicine and child neurology》1991,33(2):118-129
Tracking performance was investigated in normal and clumsy children in two age-groups, six to seven and 10 to 11 years. Target signals moving unpredictably along a straight line had to be tracked, both with and without visual feedback. Performance was described in three ways: (1) performance in the low-frequency range (LF); (2) the delay between target signal and tracking movement (DL); and (3) a measure of tracking quality or over-all similarity in the shape of target signal and tracking movement (Q). Clumsy children in both age-groups had a lower tracking quality (Q) and longer delay (DL) than the normal children. Disturbances in the regulation of attention seemed to affect tracking performance, particularly of the six- to seven-year-old clumsy children. There was no significant difference between normal and clumsy children in the effect of visual feedback on tracking performance. This suggests that clumsiness is not linked to disturbance of integration of visual feedback information and motor processes. 相似文献
994.
995.
996.
997.
998.
999.
Training needs analysis is considered essential to professional and organizational development, for continuing education and for incorporation into professional practice. Increasingly, nurses are encouraged to develop their health promotion role. Despite this there has been relatively little research in Scotland into the health promotion role of the hospital nurse. This study describes the results of a health promotion training needs analysis undertaken on qualified, hospital-based nurses in Lanarkshire, Scotland. Information on the nurses' current health promotion practices, their attitudes and beliefs, their views on role development and priorities for further training were collated, analysed and discussed within the framework of the Health Action Model. This model was originally designed to assist understanding of the gap that exists between an individual intention to act and the eventual health action. However, in this study the ways in which ‘cognitive factors’ (knowledge and beliefs) and ‘motivational factors’ (considering values, attitudes and drives) and pressures from social norms and significant others assisted in the understanding of the nurse's orientation to, and beliefs about, health promotion practice. Fifty-seven per cent of nurses in the study considered health promotion activities to be emerging in clinical care and 4% considered them to be advanced. The interest respondents have in role development and the further integration of health promotion activities into nursing practice was explored by ascertaining the nurses' attitudes and beliefs about their own health promotion role. Of 107 respondents, a majority 72 (67%) agreed health promotion interventions to be an important function of the nurse with 29 (27%) strongly agreeing (n=107). Sixty per cent stated they would be interested in developing their role and 30% were very strongly interested. Recommendations are therefore made for future planning and development strategies for the health promotion role of hospital nurses. 相似文献
1000.