全文获取类型
收费全文 | 25006篇 |
免费 | 1958篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 180篇 |
儿科学 | 971篇 |
妇产科学 | 775篇 |
基础医学 | 3418篇 |
口腔科学 | 419篇 |
临床医学 | 3340篇 |
内科学 | 4558篇 |
皮肤病学 | 336篇 |
神经病学 | 2978篇 |
特种医学 | 456篇 |
外科学 | 2139篇 |
综合类 | 319篇 |
一般理论 | 47篇 |
预防医学 | 3225篇 |
眼科学 | 453篇 |
药学 | 1738篇 |
中国医学 | 31篇 |
肿瘤学 | 1634篇 |
出版年
2023年 | 223篇 |
2022年 | 258篇 |
2021年 | 522篇 |
2020年 | 380篇 |
2019年 | 591篇 |
2018年 | 658篇 |
2017年 | 518篇 |
2016年 | 511篇 |
2015年 | 591篇 |
2014年 | 874篇 |
2013年 | 1223篇 |
2012年 | 1789篇 |
2011年 | 1859篇 |
2010年 | 982篇 |
2009年 | 947篇 |
2008年 | 1526篇 |
2007年 | 1673篇 |
2006年 | 1643篇 |
2005年 | 1532篇 |
2004年 | 1516篇 |
2003年 | 1368篇 |
2002年 | 1292篇 |
2001年 | 334篇 |
2000年 | 270篇 |
1999年 | 271篇 |
1998年 | 272篇 |
1997年 | 232篇 |
1996年 | 178篇 |
1995年 | 168篇 |
1994年 | 137篇 |
1993年 | 167篇 |
1992年 | 159篇 |
1991年 | 152篇 |
1990年 | 125篇 |
1989年 | 123篇 |
1988年 | 102篇 |
1987年 | 95篇 |
1986年 | 76篇 |
1985年 | 104篇 |
1984年 | 81篇 |
1983年 | 102篇 |
1982年 | 99篇 |
1981年 | 92篇 |
1980年 | 96篇 |
1979年 | 79篇 |
1978年 | 67篇 |
1976年 | 62篇 |
1974年 | 68篇 |
1973年 | 72篇 |
1972年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Anthony J Ireland Helen Knight Martyn Sherriff 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):323-326
Self-etching primers have recently been introduced to simplify the orthodontic bonding process. The aim of this study was to compare the effectiveness of such a product with conventional 2-stage etching and priming with 37% o-phosphoric acid and a conventional unfilled primer. Twenty consecutive patients having orthodontic bonds placed were selected to participate in this cross-mouth control study. Diagonally opposite quadrants were randomly allocated to either the self-etching primer group or the conventional etching and priming group. A total of 364 teeth were bonded with a light-cured diacrylate adhesive; bond failures were then monitored over 6 months. There were 20 bond failures (10.99%) in the self-etching primer group and 9 bond failures (4.95%) in the conventional etch and priming group over this period. The results were analyzed with the McNemar test and 95% confidence interval. The difference between the failure proportions was -0.06 with an associated 95% confidence interval of -0.121 to 0.001. This study produced weak evidence to suggest that bond failures with a self-etching primer will be higher than those with conventional etching and priming. This increased likelihood of bond failure must be weighed against the time advantage of the self-etching primer when used at the initial bonding appointment. 相似文献
14.
Martina Ballmaier Elizabeth R Sowell Paul M Thompson Anand Kumar Katherine L Narr Helen Lavretsky Suzanne E Welcome Heather DeLuca Arthur W Toga 《Neuropsychopharmacology》2004,55(4):382-389
BACKGROUND: In elderly depression, volumetric brain imaging findings suggest abnormalities of the frontal lobe, particularly the orbitofrontal cortex, and the hippocampus. No studies to date have mapped cortical abnormalities over the entire brain surface in major depression. Here, we conducted detailed spatial analyses of brain size and gray matter within the cortical mantle in elderly patients with major depression. METHODS: High-resolution, three-dimensional, structural magnetic resonance imaging data and cortical pattern matching methods were used in 24 depressed elderly patients and 19 group-matched controls to measure local brain size and proportions of gray matter at thousands of homologous cortical surface locations. RESULTS: Prominent brain size reductions were observed in the depressed subjects in the orbitofrontal cortex bilaterally. Cortical gray matter measurements revealed significant gray matter increases in the orbitofrontal cortex, adjacent to focal trend level significant decreases of gray matter in the same region. Depressed patients also exhibited significant gray matter increases in parietal cortices, as well as the left temporal cortex. CONCLUSIONS: Complex cortical changes may contribute to the brain size reduction of the orbitofrontal cortex and to the gray matter abnormalities detected in orbitofrontal cortex and temporoparietal cortices, thereby providing a potentially new window into the pathophysiology of elderly depression. 相似文献
15.
16.
Helen Penn 《Early child development and care》1995,108(1):1-18
This paper analyses the diverse services currently available for children under five in the UK, and considers the nature of the demand for them. It recounts the initiative made by Strathclyde Region to co-ordinate and integrate pre-five provision, administratively and at a service level. It then considers the efforts of other local authorities to integrate administratively and looks at some of the complexities of attempting to do so at a service level. 相似文献
17.
Patients suffering from semantic dementia provide important constraints on theories of the structure and organisation of semantic memory. In this article we report one such patient, AM, whose progressive deterioration of semantics enables us to address the much-debated issue of whether conceptual structure is hierarchically organised. The hierarchical account predicts that brain damage should impair lower levels of the hierarchy (property information) before affecting higher level (category) information (Warrington and Shallice, Q. J. Exp. Psychol. 1975, 27, 635–657). We evaluate this prediction by repeated testing of AM in two studies—a semantic priming task and a verification task—over an 18 month period, contrasting the progressive deterioration of properties (functional and perceptual) and category relations (category co-ordinates and category labels). Properties were preserved longer than category information, arguing against a hierarchical account of semantic memory. In addition, functional properties were most robust to brain damage, supporting our claim that functional information plays a special role in semantic representations (Durrant-Peatfield et al., Proc. 19th Ann. Conf. of the Cognitive Science Society. Erlbaum, Mahwah, NJ, 1997, pp. 193–198. Tyler et al., Cognitive Neuropsychol. 1997, 14, 511–545). 相似文献
18.
Systemic sclerosis secondary to occupational exposure 总被引:1,自引:0,他引:1
19.
Tsungai Chipato MRCOG David L. Healy PhD FRACOG Beverley Vollenhoven MRACOG Helen M. Buckler MRCP 《The Australian & New Zealand journal of obstetrics & gynaecology》1991,31(4):383-384
We present these 3 cases to alert others to the possibility of severe pain with rapid shrinkage of fibroids occurring during LHRH analogue treatment. We suggest management of such events should not be surgical except for vaginal excision of prolapsed fibroid polyps. 相似文献
20.
Helen Statham 《Sociology of health & illness》1994,16(3):408-410