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   133篇
  免费   16篇
耳鼻咽喉   2篇
儿科学   3篇
基础医学   40篇
口腔科学   1篇
临床医学   17篇
内科学   34篇
神经病学   4篇
特种医学   10篇
外科学   9篇
预防医学   3篇
药学   13篇
肿瘤学   13篇
  2022年   1篇
  2021年   1篇
  2020年   3篇
  2018年   1篇
  2017年   3篇
  2016年   2篇
  2015年   4篇
  2014年   5篇
  2013年   5篇
  2012年   6篇
  2011年   5篇
  2010年   3篇
  2009年   3篇
  2008年   5篇
  2007年   7篇
  2006年   5篇
  2005年   13篇
  2004年   8篇
  2003年   9篇
  2002年   13篇
  2001年   5篇
  2000年   3篇
  1999年   5篇
  1997年   3篇
  1995年   1篇
  1991年   1篇
  1990年   1篇
  1989年   4篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   2篇
  1983年   1篇
  1981年   1篇
  1980年   3篇
  1979年   2篇
  1978年   3篇
  1977年   1篇
  1974年   1篇
  1967年   1篇
  1964年   1篇
  1963年   1篇
  1937年   1篇
  1925年   1篇
  1911年   1篇
  1904年   1篇
排序方式: 共有149条查询结果,搜索用时 15 毫秒
61.
B-cell chronic lymphocytic leukemia (CLL) is not a uniform disease entity; approximately half of the CLL cases have undergone immunoglobulin V(H) gene hypermutation, whereas the other half display unmutated V(H) genes. We investigated genome changes in 12 hypermutated cases (M-CLL) and 22 unmutated cases (UM-CLL) by use of comparative genomic hybridization, G-banding, and multicolor fluorescence in situ hybridization (m-FISH) after optimal mitogen stimulation and FISH analysis of typical CLL aberrations: 11q deletion, 13q deletion, and trisomy 12. Very high frequencies of aberrations were found in both groups: 82% in UM-CLL and 83% in M-CLL. Deletions of 11q and 13q were equally distributed in M-CLL and UM-CLL. However, larger aberrations detectable by CGH, trisomy 12, and complex aberrations were less frequent in M-CLL than in UM-CLL. These observations led to a hypothesis that unmutated and mutated CLL have different biological Backgrounds, given that large and/or complex chromosomal aberrations and hypermutation of the CLL progenitor cells tend to be mutually exclusive.  相似文献   
62.
It has been shown that the primary and secondary somatosensory cortex, as well as the supplementary motor area (SMA), are involved in central processing of proprioceptive signals during passive and active arm movements. However, it is not clear whether different cortical areas are involved in processing of different proprioceptive inputs (skin, joint, muscle receptors), what their relative contributions might be, where kinesthetic sensations are formed within the CNS, and how they interact when the full peripheral proprioceptive machinery acts. In this study we investigated the representation of the brain structures involved in the perception of passive limb movement and illusory movement generated by muscle tendon vibration. Changes in cortical activity as indicated by changes in regional cerebral blood flow (rCBF) were measured using positron emission tomography (PET). Twelve subjects were studied under four conditions: (1) passive flexion-extension movement (PM) of the left forearm; (2) induced illusions of movements (VI) similar to the real PM, induced by alternating vibration of biceps and triceps tendons (70-80 Hz) at the elbow; (3) alternating vibration of biceps and triceps tendons (with 20-50 Hz) without induced kinesthetic illusions (VN); and (4) rest condition (RE). The results show different patterns of cortex activation. In general, the activation during passive movement was higher in comparison with both kinds of vibration, and activation during vibrations with induced illusions of movement was more prominent than during vibrations without induced illusions. When the PM condition was contrasted with the other conditions we found the following areas of activation -- the primary motor (MI) and somatosensory area (SI), the SMA and the supplementary somatosensory area (SSA). In conditions where passive movements and illusory movements were contrasted with rest, some temporal areas, namely primary and associative auditory cortex, were activated, as well as secondary somatosensory cortex (SII). Our data show that different proprioceptive inputs, which induce sensation of movement, are associated with differently located activation patterns in the SI/MI and SMA areas of the cortex. In general, the comparison of activation intensities under different functional conditions indicates the involvement of SII in stimulus perception generation and of the SI/MI and SMA areas in the processing of proprioceptive input. Activation of the primary and secondary auditory cortex might reflect the interaction between somatosensory and auditory systems in movement sense generation. SSA might also be involved in movement sense generation and/or maintenance.  相似文献   
63.
64.
65.
The communication of four children with autistic spectrum disorder was investigated when they were supplied with a speech-generating device (SGD) in three different activities in their home environment: mealtime, story reading and "sharing experiences of the preschool day". An activity based communication analysis, in which collective and individual background factors for the activities were outlined, was used as a basis for the discussion of linguistic coding data derived from video-recordings made before and during SGD intervention. The coded communicative behaviours were engagement in activity, role in turn-taking, communicative form, function and effectiveness. An increase in communicative effectiveness was more noticeable when the SGDs could be used to fulfil goals and roles within the activity. The instruction to the parents to use the SGDs in their communication with the child had an important influence on the activities.  相似文献   
66.
67.
Previous studies indicate that the inflammatory response in diffuse large B-cell lymphomas (DLBCL) is important for the clinical outcome. Mast cells are key regulators in this response; we investigated whether the number of tryptase-positive mast cells is correlated with clinical outcome. Patients with many mast cells had a significantly better event-free survival (EFS) compared to those with few mast cells (P < 0.03 in both germinal centre (GC) and non-GC DLBCL. This supports the idea that the infiltration of mast cells is a reflection of the host inflammatory response and is related to a favourable outcome.  相似文献   
68.
Inflammatory bowel disease (IBD) can be treated effectively by anti-tumour necrosis factor (TNF) therapy. We set out to investigate the unclear immunoregulatory mechanisms of the treatment. Thirty-four patients with IBD treated with anti-TNF were included. Lymphocytes from peripheral blood and intestinal biopsies were analysed by flow cytometry. Regulation of antigen-stimulated proliferation was analysed by blocking of interleukin (IL)-10, transforming growth factor (TGF)-β or depletion of CD25(+) cells in peripheral blood mononuclear cell cultures. No changes in CD4(+)CD25(+), CD25(+)TNF-RII(+) or CD4(+)CD25(+) forkhead box protein 3 (FoxP3(+)) T cells could be observed in peripheral blood after, in comparison to before, 6 weeks of treatment. The suppressive ability of CD4(+)CD25(+) cells did not change. There was an initial decrease of CD4(+)CD25(+) cells in intestinal mucosa after 2 weeks of treatment, followed by an increase of these cells from weeks 2 to 6 of treatment (P < 0·05). This was accompanied by an increased percentage of CD69(+) cells among these cells after 6 weeks of treatment compared to before treatment (P < 0·01). There was also an increase of mucosal T helper type1 cells from weeks 2 to 6 (P < 0·05). In addition, CD25(+)TNF-RII(+) cells in the mucosa were decreased after 6 weeks of treatment compared to before treatment (P < 0·05). Before treatment, peripheral blood mononuclear cell baseline proliferation was increased when IL-10 was blocked (P < 0·01), but not after. In CD25(+) cell-depleted cultures proliferation increased after treatment (P < 0·05). Our data indicate that anti-TNF treatment leads to an induction of effector T cells. Anti-TNF therapy has no significant impact on regulatory T cells in IBD, although the composition of regulatory T cell subsets may change during treatment.  相似文献   
69.
An octasaccharide with high affinity for antithrombin was isolated after partial deaminative cleavage of heparin with nitrous acid. After conversion of the 2,5-anhydro-D-mannose end group to anhydro[1-3H]mannitol, labeled pentasaccharide was released from the octasaccharide by periodate-alkali treatment. Incubation of the pentasaccharide with a recently discovered 3,O-sulfatase from human urine resulted in desulfation, suggesting the occurrence of a 3-sulfate group on the terminal glucosamine residue. The same glucosamine residue was recovered as a 2,5-anhydro[1-3H]mannitol derivative by a procedure involving deamination of the octasaccharide with nitrous acid, reduction of the products with sodium boro[3H]hydride, isolation of 3H-labeled tetrasaccharide by gel chromatography, and release of the labeled end-group by periodate-alkali treatment. Paper electrophoresis indicated disulfated anhydro[3H]mannitol, presumably sulfated at C3 and C6, as a major component, along with smaller amounts of monosulfated (presumably 3-sulfated) anhydro[3H]mannitol. Similar treatment of an analogous tetrasaccharide derived from heparin with low affinity for antithrombin failed to produce any disulfated anhydromannitol. These results suggest that 3-sulfated glucosamine is a unique component of high-affinity heparin, located at a specific position in the antithrombin-binding sequence of the molecule.  相似文献   
70.
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