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   1645篇
  免费   172篇
  国内免费   5篇
耳鼻咽喉   10篇
儿科学   75篇
妇产科学   45篇
基础医学   338篇
口腔科学   24篇
临床医学   133篇
内科学   308篇
皮肤病学   30篇
神经病学   80篇
特种医学   103篇
外科学   271篇
综合类   8篇
预防医学   86篇
眼科学   39篇
药学   121篇
中国医学   3篇
肿瘤学   148篇
  2022年   13篇
  2021年   22篇
  2020年   19篇
  2019年   29篇
  2018年   24篇
  2017年   29篇
  2016年   33篇
  2015年   34篇
  2014年   56篇
  2013年   75篇
  2012年   113篇
  2011年   110篇
  2010年   74篇
  2009年   69篇
  2008年   116篇
  2007年   117篇
  2006年   124篇
  2005年   111篇
  2004年   79篇
  2003年   69篇
  2002年   53篇
  2001年   32篇
  2000年   19篇
  1999年   18篇
  1998年   15篇
  1997年   11篇
  1996年   13篇
  1995年   15篇
  1994年   8篇
  1993年   16篇
  1992年   29篇
  1991年   26篇
  1990年   13篇
  1989年   17篇
  1988年   20篇
  1987年   22篇
  1986年   19篇
  1985年   18篇
  1984年   14篇
  1983年   8篇
  1982年   11篇
  1980年   11篇
  1979年   13篇
  1978年   6篇
  1977年   6篇
  1976年   8篇
  1974年   9篇
  1972年   7篇
  1970年   8篇
  1967年   5篇
排序方式: 共有1822条查询结果,搜索用时 15 毫秒
1.
2.
3.
J Dvorak  D Grob  H Baumgartner  N Gschwend  W Grauer  S Larsson 《Spine》1989,14(10):1057-1064
Thirty-four patients with atlanto-axial instability due to rheumatoid arthritis were examined with plain x-ray views and functional magnetic resonance imaging (MR), and were neurologically evaluated. Transcranial brain stimulation was performed in 25 patients. In 22 cases, the authors observed inflammatory tissue thicker than 3 mm behind the odontoid peg. The spinal canal diameter was significantly decreased in the flexed position. Nine patients showed signs of cranial migration of the axis. The diameter of the spinal cord was measured to be 7.4 mm in the neutral position, and 6.5 mm in flexion. The difference between the diameter of the neutral and flexed positions was highly significant. Twelve of the 34 patients displayed clinical signs of cervical myelopathy, and 13 showed a significant delay of central motor latency, as calculated from the motor evoked potentials. Surgical intervention, either by a posterior approach only or combined with a transoral dens and inflammatory tissue resection, is recommended in patients with progressive atlanto-axial instability, pathologic clinical and neurophysiologic findings, and a spinal cord diameter of less than 6 mm in flexion. Severe pain and cranial migration of the axis, as measured by the MRI, also justify a surgical intervention.  相似文献   
4.
J Dvorak  J Hayek  R Zehnder 《Spine》1987,12(8):726-731
Nine healthy adults and 43 patients with cervical spine injury were examined by using functional (computerized tomography) CT scanning. The ranges of axial rotation at the levels occiput C0-C1, C1-C2, and C2-C3 were measured. A rotation at C0-C1 greater than 8 degrees; at C1-C2, 56 degrees; or a right-left difference C0-C1 greater than 5 degrees and C1-2 greater than 8 degrees indicates hypermobility. A rotation at segment C1-C2 of less than 28 degrees indicates hypomobility. Surgical stabilization of rotatory instability could be considered as a possible therapeutic procedure.  相似文献   
5.
A knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemicsl typcal analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type-IIB (fast-twitch glycolytic) fibres than type- I (slow oxidatve) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle iccupied by type-IIB fibres was higher and that by type-I fibres Was lower in the patients. The patients had a greater number of muscle samples with more than 1% type-IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.  相似文献   
6.
7.
The relationship between the use of cigarettes and other tobacco products and the risk of multiple myeloma was examined in a cohort of nearly 250,000 American veterans followed prospectively for 26 years. Compared with men who had never used tobacco, the risk of death from myeloma was not increased among current (relative risk [RR]=0.9, 95 percent confidence interval [CI]=0.8–1.2) or former (RR=1.0, CI=0.8–1.3) cigarette smokers, nor among users of chewing tobacco or snuff (RR=1.0, CI=0.4–2.3). Risk was only slightly and nonsignificantly increased among pipe or cigar smokers (RR=1.2, CI=0.9–1.5). There was no indication of increasing risk with amount of tobacco used or earlier age at first use. With over 90 percent power to detect a 30 percent increased risk of this tumor occuring among current cigarette smokers, this study provides the strongest evidence to date against an association of cigarette smoking with multiple myeloma.Epidemiology and Biometry Program, Division of Cancer Etiology, National Cancer Institute. Westat, Inc. Rockville, MD. National Cancer Institute, 6130 Executive Blvd, Room 418, Rockville, MD 20892, USA.  相似文献   
8.
9.
A single-purpose analogue-computing device is described for the online assessment of the contractile state of the human myocardium from the left ventricular pressure (Plv) data available during routine cardiac catheterisation. Due attention has been paid to the design of the computer circuits so that they will not process pressure phenomena outside the isovolumic contractile period. Either a \(\left( {\frac{1}{{P_{lv} }}\frac{{dP_{lv} }}{{dt}}} \right)_{max} \) or a plain \(\left( {\frac{{dP_{lv} }}{{dt}}} \right)_{max} \) index is presented on a digitalvoltmeter display, thus obviating the need for any graphical extrapolation or additional computation.  相似文献   
10.
The mechanism of piecemeal degranulation by human eosinophils was investigated. Mature eosinophils that developed in rhIL-5-containing conditioned media from cultured human cord blood mononuclear cells were prepared for ultrastructural studies using a combined technique to image eosinophil peroxidase by cytochemistry in the same sections on which postembedding immunogold was used to demonstrate Charcot-Leyden crystal protein. Vesicular transport of eosinophil peroxidase from the specific granule matrix compartment to the cell surface was associated with piecemeal degranulation. This process involved budding of eosinophil peroxidase-loaded vesicles and tubules from specific granules. Some eosinophil peroxidase that was released from eosinophils remained bound to the cell surface; some was free among the cultured cells. Macrophages and basophils bound the released eosinophil peroxidase to their plasma membranes, internalized it in endocytotic vesicles, and stored it in their respective phagolysosomes and secretory granules. Charcot-Leyden crystal protein was diffusely present in the nucleus and cytoplasm of IL-5-stimulated mature eosinophils. Extensive amounts were generally present in granule-poor and subplasma membrane areas of the cytoplasm in contrast to eosinophil peroxidase, which was secreted and bound to the external surface of eosinophil plasma membranes. These studies establish vesicular transport as a mechanism for emptying the specific eosinophil granule matrix compartment during IL-5-associated piecemeal degranulation.  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