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   35443篇
  免费   2341篇
  国内免费   435篇
耳鼻咽喉   387篇
儿科学   951篇
妇产科学   668篇
基础医学   5033篇
口腔科学   2671篇
临床医学   2907篇
内科学   6706篇
皮肤病学   707篇
神经病学   2547篇
特种医学   869篇
外国民族医学   2篇
外科学   4149篇
综合类   1401篇
一般理论   8篇
预防医学   3716篇
眼科学   517篇
药学   2791篇
  6篇
中国医学   552篇
肿瘤学   1631篇
  2023年   323篇
  2022年   825篇
  2021年   1347篇
  2020年   912篇
  2019年   1108篇
  2018年   1262篇
  2017年   969篇
  2016年   996篇
  2015年   1241篇
  2014年   1517篇
  2013年   1783篇
  2012年   2676篇
  2011年   2911篇
  2010年   1606篇
  2009年   1256篇
  2008年   1927篇
  2007年   1855篇
  2006年   1736篇
  2005年   1448篇
  2004年   1382篇
  2003年   1346篇
  2002年   1235篇
  2001年   927篇
  2000年   834篇
  1999年   623篇
  1998年   256篇
  1997年   191篇
  1996年   164篇
  1995年   150篇
  1994年   131篇
  1993年   113篇
  1992年   270篇
  1991年   260篇
  1990年   249篇
  1989年   233篇
  1988年   221篇
  1987年   166篇
  1986年   150篇
  1985年   164篇
  1984年   125篇
  1983年   94篇
  1979年   104篇
  1978年   91篇
  1975年   80篇
  1974年   88篇
  1973年   84篇
  1971年   57篇
  1970年   69篇
  1969年   60篇
  1967年   70篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Nonvisual perceptions of a wielded object's spatial properties are based on the quantities expressing the object's mass distribution, quantities that are invariant during the wielding. The mechanoreceptors underlying the kind of haptic perception involved in wielding – referred to as effortful, kinesthetic, or dynamic touch – are those embedded in the muscles, tendons, and ligaments. The present experiment's focus was the selectivity of this muscle-based form of haptic perception. For an occluded rod grasped by the hand at some intermediate position along its length, participants can attend to and report selectively the rod's full length, its partial lengths (fore or aft of the hand), and the position of the grip. The present experiment evaluated whether participants could similarly attend selectively when wielding by foot. For a given rod attached to and wielded by foot or attached to (i.e. grasped) and wielded by hand, participants reported (by magnitude production) the rod's whole length or fractional length leftward of the point of attachment. On measures of mean perceived length, accuracy, and reliability, the degree of differentiation of partial from full extent achieved by means of the foot matched that achieved by means of the hand. Despite their neural, anatomical, and experiential differences, the lower and upper limbs seem to abide by the same principles of selective muscle-based perception and seem to express this perceptual function with equal facility.  相似文献   
82.
We document here by Western immunoblotting and immunogold ultracytochemistry that polyclonal antibodies against human lactoferrin (Lf) bind to tubercle and leprosy bacilli. In situ immunogold labeling of Mycobacterium leprae (present in armadillo liver and in human skin) and of Mycobacterium tuberculosis indicated that receptors for anti-Lf antibodies were present both on the cytoplasm and on the envelope of the bacilli. We found by immunoblotting that the 65-kDa heat shock protein is the major component of M. leprae and M. tuberculosis that is responsible for the binding of the anti-Lf probe. Furthermore, we show that anti-Lf immunoglobulin G eluted from the nitrocellulose-transferred mycobacterial 65-kDa protein band did bind back to Lf. Ultracytochemistry of biopsy samples of human lepromas showed that dead or severely damaged M. leprae was strongly marked by the anti-Lf antibodies; a similar pattern of immunogold marking was observed on M. leprae when antibodies against the 65-kDa mycobacterial protein were used. Our results offer direct evidence that the 65-kDa protein of leprosy and tubercle bacilli is recognized with specificity by antibodies against the human protein Lf. The Lf-65-kDa protein antigenic cross-reactivity may contribute to the formation of autoantibodies and immune complexes as well as to other autoimmune events that are frequent in tuberculosis and leprosy. Our immunocytochemical data also suggest that the cross-reactivity may persist for some time after the death of mycobacteria in infected hosts.  相似文献   
83.
84.
A Rebollo  A Silva 《Immunology》1993,80(2):229-235
We have previously described a synergism between the two physiological hormones, retinoic acid (RA) and 1 alpha,25-dihydroxyvitamin D3 (VD) in the induction of U937 cell differentiation towards a more mature state. Herein, we investigated the regulation of cytokine production during RA and/or VD treatment of U937 cells. Cell differentiation was followed by measurement of their capacity to give oxidative responses, and interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and IL-6 gene and protein expression were determined in RA/VD-treated cells, activated or not with lipopolysaccharide (LPS). The undifferentiated and RA-treated U937 cells were unable to produce monokines even when they were stimulated by LPS. VD induced the monokine mRNA expression in U937 cells but failed to induce protein release. However, unlike RA, it primed the cells to secrete monokines upon endotoxin stimulation. A large enhancement of the production of the monokines both at mRNA and protein levels was observed in the U937 cells exposed to the combination of RA + VD. Nevertheless, protein release required a further step of activation of the RA + VD-primed cells. The co-inducer effect of RA and VD was not observed in HL-60 or THP-1 cells and seems to be restricted to U937 cells. These results on cytokine expression support our previous finding that a combination of RA and VD brings the U937 cells to a high stage of myeloid differentiation with major characteristics of monocytes/macrophages.  相似文献   
85.
Abstract

The stethoscope is a major symbol of modern medicine. It is used for diagnosis of different conditions and enables physicians to listen to internal body sounds. Electrocardiography was only introduced in medicine in the beginning of the twentieth century. Today measuring heart’s electrical activity is also fundamental cardiac diseases diagnosis. Although performed with independent devices, requiring physician and patient presence in the same physical space, in combination they enhance cardiovascular assessment. In this paper, a digital stethoscope encapsulation was designed, adding new functionality to this advanced medical device. Today wired and wireless communications enable different medical devices to share data and information, over long distances. Using low-cost hardware technologies, the encapsulation will add the ability to acquire and transmit via Bluetooth the Electrocardiographic activity, determined in the same cardiac focus and synchronised with the Phonocardiographic sound recordings. Several encapsulation concepts were developed and prototyped using 3D printing. They were easily fitted to the digital stethoscope and tested in a hospital environment for ergonomics, acoustic and electric signals acquisition. The best concept was chosen with the help of a physician’s opinion and the final prototype performance was very satisfactory.  相似文献   
86.
87.
88.
89.
90.
Within the context of WHO/CDS/RBM/2000, a survey was conducted in 2001 by the National Malaria Control Program of Benin. Following a well-thought-out choice, the survey took place simultaneously in health areas corresponding to epidemiological regions. Morbidity due to malaria is very high among children under five years admitted in external clinic (44.3% of cases) and (46.5%) for hospitalization. The crude rate of mortality is 129%. The use of non-impregnated bednet is usually met in three health areas, where 47.4% of the household have at least one non-impregnated bednet versus 5.4% of household with impregnated bednets. Percentage of pregnant women sleeping under an impregnated bednet and following chemoprophylaxis is respectively 43.3% and 3.8%. Results obtained at the end of this database survey in 2001 have facilitated the definition of indicators of the process, results and impact which remain very useful for the implementation of the monitoring and assessment system of "Roll Back Malaria" in Benin.  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