全文获取类型
收费全文 | 25019篇 |
免费 | 1832篇 |
国内免费 | 533篇 |
专业分类
耳鼻咽喉 | 285篇 |
儿科学 | 598篇 |
妇产科学 | 365篇 |
基础医学 | 3030篇 |
口腔科学 | 560篇 |
临床医学 | 2522篇 |
内科学 | 4008篇 |
皮肤病学 | 666篇 |
神经病学 | 1767篇 |
特种医学 | 1140篇 |
外国民族医学 | 25篇 |
外科学 | 2913篇 |
综合类 | 1928篇 |
现状与发展 | 6篇 |
一般理论 | 6篇 |
预防医学 | 2649篇 |
眼科学 | 273篇 |
药学 | 2463篇 |
13篇 | |
中国医学 | 972篇 |
肿瘤学 | 1195篇 |
出版年
2022年 | 298篇 |
2021年 | 489篇 |
2020年 | 340篇 |
2019年 | 327篇 |
2018年 | 420篇 |
2017年 | 403篇 |
2016年 | 418篇 |
2015年 | 610篇 |
2014年 | 743篇 |
2013年 | 1004篇 |
2012年 | 1459篇 |
2011年 | 1461篇 |
2010年 | 1060篇 |
2009年 | 1007篇 |
2008年 | 1388篇 |
2007年 | 1373篇 |
2006年 | 1304篇 |
2005年 | 1235篇 |
2004年 | 954篇 |
2003年 | 941篇 |
2002年 | 804篇 |
2001年 | 712篇 |
2000年 | 721篇 |
1999年 | 548篇 |
1998年 | 210篇 |
1997年 | 165篇 |
1996年 | 140篇 |
1995年 | 166篇 |
1994年 | 204篇 |
1993年 | 263篇 |
1992年 | 594篇 |
1991年 | 545篇 |
1990年 | 449篇 |
1989年 | 301篇 |
1988年 | 286篇 |
1987年 | 286篇 |
1986年 | 242篇 |
1985年 | 275篇 |
1984年 | 207篇 |
1983年 | 150篇 |
1982年 | 125篇 |
1979年 | 168篇 |
1978年 | 135篇 |
1977年 | 127篇 |
1976年 | 138篇 |
1975年 | 144篇 |
1974年 | 182篇 |
1973年 | 155篇 |
1971年 | 135篇 |
1970年 | 124篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
111.
增白牙膏去除牙面外源性色素临床实验 总被引:2,自引:0,他引:2
目的测试一种增白牙膏用于减少牙面外源性色素的效果. 方法 研究对象121例,年龄21~57岁.实验组60例,对照组61例,两组年龄和性别分布差异无显著性.采用双盲法两组平行设计,根据Lobene色斑指数(LSI)和性别均衡分为两组,随机分配使用实验牙膏或对照牙膏.实验组牙膏含3 %植酸钠和1.3 %焦磷酸钠,对照组牙膏不含相应成分.临床检查分别在基线、3周和6周后进行,由同一人测定LSI.问卷询问刷牙情况. 结果 基线检查、实验3周和6周后实验组LSI分别为3.00、2.16和1.47, 对照组分别为3.10、3.08和2.18.基线检查两组LSI差别无显著性意义, 实验3周和6周后两组LSI比较差异均有显著性意义. 实验组LSI在3周和6周后分别比基线时降低28 %和51 %. 结论含3 %植酸钠和1.3 %焦磷酸钠牙膏能有效减少牙面色素,效果随使用时间而增强. 相似文献
112.
Dr. med. habil. Karl -Heinz Wagner 《Journal of molecular medicine (Berlin, Germany)》1941,20(22):574-576
Zusammenfassung Bei normal ernährten und Vitamin A-frei ernährten Ratten wird bei Sesamölzugabe keine Erhöhung der Thrombocyten beobachtet. Auch bei Gesunden und Kranken mit einer relativen Thrombopenie gelang es nicht, durch Verabreichung von Sesamöl die Thrombocyten zur Norm zu steigern. Die Anwesenheit des Faktors T im Sesamöl wird abgelehnt. 相似文献
113.
A wireless device for the assessment of tardive dyskinesia by means of digital image processing is presented. Four skin-cream dots placed around the subjects' mouth are recorded by a video camera. The image is passed to a framegrabber with a signal processor, where it is converted from analogue to digital. A fast spot-detecting algorithm implemented on the signal processor tracks the dots and passes the information to a personal computer, where a Fourier transformation is performed to calculate the frequency spectrum of the movements. The device provided detailed information on the magnitude and on the frequencies of the movements. Data from a longitudinal investigation suggest a higher sensitivity and reliability than conventional rating scales to detect and evaluate abnormal perioral movements. The device might be useful for the early detection, for the longitudinal assessment (p.e. clinical trials) and in some cases for the differential diagnosis of tardive dyskinesia, thus providing a tool for both research and clinical purposes. 相似文献
114.
A 53-year-old black man developed femoral thrombophlebitis in 1983 following a Harrington nail implantation in his first lumbar vertebral region. There was evidence of pulmonary embolization at that time and recurrently until he developed ventricular fibrillation and died in 1987. The terminal event followed a hypotensive episode during the course of a right ventricular catheterization. Autopsy confirmed the clinical impression that he had multiple recurrent thromboemboli to his lungs. After several years of embolization, the pulmonary arterial circulation was sufficiently occluded to result in pulmonary hypertension. Cor pulmonale was produced, with congestive heart failure leading to a progressively downhill course in the 4 months before his death. 相似文献
115.
116.
117.
118.
Although accustomed to using the Maquet tibial tuberosity advancement, the authors had two similar and rare complications in which a fracture of the tibial shaft occurred at the end of the vertical osteotomy. Both incidents arose from a mechanical incision effect. This can be prevented by making a larger circular hole in the distal portion of the osteotomy. 相似文献
119.
A L Wagner F R Murtagh K S Hazlett J A Arrington 《AJNR. American journal of neuroradiology》1997,18(4):723
PURPOSETo develop an objective method for measuring the optic chiasm and to document its normal range in size.METHODSMeasurements of the height and area of the optic chiasm, made on coronal T1-weighted MR images with the use of commercially available region-of-interest software, were obtained in 114 healthy subjects who had a total of 123 MR studies. A normal range and standard deviation were calculated, and the information was broken down by age and sex.RESULTSThe mean area of the optic chiasm was 43.7 mm2, with a standard deviation of 5.21. The mean width was 14.0 mm, with a standard deviation of 1.68.CONCLUSIONThe area and width of the optic chiasm can be measured with the use of commercially available software, which allows an objective estimate of the chiasm''s size. Knowledge of the normal size range of the optic chiasm can be helpful in the early detection of some disorders. 相似文献
120.
Proliferative and cytolytic responses of human gamma delta T cells display a distinct specificity pattern.
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The function and physiological role of gamma delta T cells are still unknown. Concerning the specificity of these cells, a proliferative response towards microbial ligands has been noted, whereas in terms of effector functions in humans a cytolytic activity against a variety of tumour targets is most prominent. Here we show data demonstrating that the cytolytic activity of activated human gamma delta T cells does not reflect the specificity of these cells in primary in vitro stimulation; moreover, we provide evidence that the recognition of target cells by gamma delta T cells can have different qualities. gamma delta T cells proliferate vigorously in primary in vitro reaction upon stimulation with various B-cell tumour lines but not with the T-cell lines Jurkat or Molt-4. However, gamma delta T cells stimulated primarily with phytohaemagglutinin or with cells from B-cell lines gain unrestricted cytolytic activity against a broad set of tumour targets, including Jurkat and Molt-4; the same set of targets is capable of inducing release of serine esterases (SE) from gamma delta T-effector cells. Whereas the cytolytic activity in the 51Cr-assay against the B-cell lines and against Molt-4 depends on the presence of Ca2+ ions in the assay, the lysis of Jurkat cells is only slightly reduced upon removal of Ca2+ from the medium; the SE release, however, is Ca2+ dependent in all cases. Taken together, these data suggest several different ways of target cell recognition by gamma delta T cells leading to either proliferation or triggering of cytolytic activity, and argue against an involvement of the gamma delta T-cell receptor in the cytotoxic activity of gamma delta T cells. 相似文献