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   665篇
  免费   29篇
  国内免费   19篇
耳鼻咽喉   1篇
儿科学   39篇
妇产科学   8篇
基础医学   68篇
口腔科学   30篇
临床医学   61篇
内科学   118篇
皮肤病学   5篇
神经病学   82篇
特种医学   110篇
外科学   32篇
综合类   9篇
预防医学   43篇
眼科学   2篇
药学   30篇
中国医学   2篇
肿瘤学   73篇
  2023年   3篇
  2022年   2篇
  2021年   2篇
  2019年   14篇
  2018年   12篇
  2017年   7篇
  2016年   12篇
  2015年   11篇
  2014年   14篇
  2013年   37篇
  2012年   23篇
  2011年   23篇
  2010年   30篇
  2009年   30篇
  2008年   15篇
  2007年   20篇
  2006年   19篇
  2005年   12篇
  2004年   22篇
  2003年   10篇
  2002年   12篇
  2001年   6篇
  2000年   10篇
  1999年   12篇
  1998年   32篇
  1997年   34篇
  1996年   29篇
  1995年   24篇
  1994年   25篇
  1993年   22篇
  1992年   11篇
  1991年   5篇
  1990年   11篇
  1989年   25篇
  1988年   23篇
  1987年   12篇
  1986年   22篇
  1985年   13篇
  1984年   12篇
  1983年   10篇
  1982年   15篇
  1981年   7篇
  1980年   5篇
  1978年   3篇
  1976年   2篇
  1975年   6篇
  1970年   1篇
  1969年   1篇
  1941年   1篇
  1910年   1篇
排序方式: 共有713条查询结果,搜索用时 0 毫秒
51.
Standard single-unit recording and stimulation techniques were used to assess the topographic organization, receptive field properties, and projections of cells (n = 297) in the ophthalmic-maxillary part of the trigeminal ganglion in 6 normal adult rats and 15 adults with unilateral infraorbital nerve section at birth (cells recorded ipsilateral to lesion: n = 641; cells recorded on the intact side: n = 223). Stimulating electrodes were placed on the central portion of the regenerate infraorbital nerve and in the trigeminal brain stem subnucleus caudalis in 6 nerve-damaged rats and at equivalent points in 5 normal animals. Data from the normal rats and the intact side of the nerve-damaged animals were identical and were considered together. Of these cells, 73.5% had infraorbital receptive fields. Of these, 77.2% were discharged by vibrissa stimulation (43.8% slow-adapt type I, 10.3% slow-adapt type II, 27.6% low-velocity sensitive rapid adapt, 16.8% high-velocity sensitive rapid adapt, and 1.5% noxious-biased), while the rest responded best to guard hair deflection (12.0%), gentle skin indentation (4.5%), or a strong pinch or deep pressure (6.3%). In stereotaxically matched penetrations in ganglia ipsilateral to the neonatal infraorbital nerve lesions, only 40.6% of the cells had infraorbital receptive fields. Of these, only 37.7% responded to vibrissa stimulation (29.8% slow-adapt type I, 1.2% slow-adapt type II, 2.2% low-velocity sensitive rapid adapt, 32.9% high-velocity sensitive rapid adapt, 33.9% noxious). Other infraorbital cells responded best to guard hair deflection (11.9%), gentle skin indentation (10.8%), or a strong pinch or deep pressure (39.6%). An additional 30 cells did not have a detectable receptive field and were identified only by infraorbital and brain-stem shocks. We also recorded cells with unusual infraorbital receptive fields: 9 units responded to more than 1 vibrissa, 4 were activated by both vibrissa and guard hair deflection, 10 had unusually large skin or deep receptive fields, 1 had a split receptive field, and 7 were discharged only by deep pressure to the region of the nerve section. Seven cells with infraorbital receptive fields were not driven by infraorbital shocks, and 2 were not activated by brain-stem shocks. In normal rats, all cells with infraorbital receptive fields were driven by both electrodes. The percentages of receptive field types for noninfraorbital cells were unchanged in ganglia ipsilateral to the damaged nerve.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
52.
Meyerovitz  MF; Reagan  K; Friedman  PL 《Radiology》1989,171(3):866-868
Posteroanterior (PA) and caudally angulated PA views were obtained in 20 patients undergoing routine coronary arteriography. Although the left main coronary artery (LMCA) was seen well on both views in all patients, the PA-caudal view improved depiction of the LMCA bifurcation in 15 (75%). In addition, the PA-caudal view markedly improved depiction of the circumflex artery, affording optimal depiction of this artery and its branches in 78%-89% of patients. Neither the PA nor the PA-caudal view allowed adequate depiction of the left anterior descending artery. Thus, the PA-caudal view should supplant the PA view in routine coronary arteriography.  相似文献   
53.
Reconstruction of facial burn sequelae]   总被引:2,自引:0,他引:2  
The deep burns of the face can lead to horrible scars functionally and aesthetically. Treatment of these scars need several surgical interventions frequently and during many years. In our region we deal with this type of wounds as team work, multidisciplinary approach carrying out many process starting by emergency treatment of acute burns till the social rehabilitation. The expansion technique was great help in improving the shape of scars, by using the expanding skin as full thickness grafts. Reconstruction of the anatomical units and application of aesthetic techniques (like rhinoplasty, lifting, tattooing and autologous fat injections) participate equally in improving the quality of results. Many examples of treatments of burns scars are shown.  相似文献   
54.
Intracellular recording and horseradish peroxidase (HRP) injection techniques were used to delineate the structural and functional characteristics of the superior collicular cells in the hamster, which could be antidromically activated from the first cervical segment of the spinal cord. Thirty-one such neurons were characterized, filled with HRP, and recovered. Complete physiological data were obtained from another 21 tectospinal cells for which anatomical data were sufficient only to define the laminar location of the cell body from which recordings were made. Of the total sample of 52 cells, 7.7% had their somata in the stratum griseum intermediale (SGI), 50% were in the stratum album intermedium (SAI), 36.5% were in the stratum griseum profundum (SGP), and 5.8% were in the stratum album profundum (SAP). The tectospinal cells were fairly uniform morphologically. They had large (27.7 +/- 5.5 microns diameter) cell bodies, which gave rise to an average of 6.7 +/- 1.2 primary dendrites. These were generally smooth and extended up to 500 microns away from the cell body. In many cases, they ascended out of the deep laminae into the stratum opticum (SO) and/or stratum griseum superficiale (SGS). The axons of TS cells averaged 3.4 +/- 0.8 microns in diameter, and they generally coursed radially to the SAP where they curved around the periaqueductal gray and entered the predorsal bundle. These axons often gave rise to collaterals that arborized in the deep laminae of the ipsilateral superior colliculus and subjacent reticular formation. The tectospinal cells were also fairly uniform physiologically. Their average conduction latency was 2.0 +/- 2.3 ms, and this variable had a strong negative correlation (-.81) with axon diameter for the recovered cells. Most (63.5%) of the TS cells were exclusively somatosensory and gave rapidly adapting responses to deflection of vibrissae and/or guard hairs; 7.7% were bimodal (visual-somatosensory); 11.5% had complex (Rhoades et al., '83) somatosensory receptive fields; 1.9% were discharged only by a noxious pinch, and 15.4% were unresponsive. A common feature of all bimodal tectospinal neurons was dendrites that extended at least as far dorsally as the SO. Whereas there were no other clear-cut correlations between the structural and functional characteristics of these tectal neurons, we did note that all of the cells with complex somatosensory receptive fields received inhibitory input from axons that either originated from, or passed through, the contralateral superior colliculus.  相似文献   
55.
BACKGROUND: In routine practice, the evaluation of the nutritional status of patients with cancer is not always performed although there is frequent modification as disease progresses. The validated screening and evaluation tools currently available are time-consuming and costly. In this study we analysed factors that could be used to identify patients likely to need nutritional surveillance or intervention. PATIENTS AND METHODS: A cross-sectional survey was carried out for 2 weeks in June 2006 on 477 patients with cancer. RESULTS: 30.2% of the patients had lost more than 10% of their body weight since the start of the illness. After adjustment, the factors significantly associated with weight loss were: depressive state (OR = 3.49; P = 0.002), digestive or ENT tumours (OR = 3.20; P = <0.001), chemotherapy (OR = 2.66; P = 0.011), male gender (OR = 2.30; P = 0.001) and professional status (OR = 2.08; P = 0.02). Using a logistic model, we calculated the risk of weight loss as a function of the presence of the identified predictive factors. CONCLUSION: We report a simple screening tool, which will not replace the available evaluation methods but will enable targeting of the patients most likely, after a specific evaluation, to benefit from nutritional intervention. This remains to be validated in further prospective studies.  相似文献   
56.
目的:观察低血糖指数的膳食对2型糖尿病患者氧化应激状态的影响。方法:2004-10/11在上海市静安区二个社区卫生服务中心招募受试者,经医生明确诊断为2型糖尿病、病程超过6个月,体质量指数≥24kg/m2的老年糖尿病志愿者43名,受试者对试验知情同意。采用随机交叉试验随机分配至低血糖指数饮食组和高血糖指数饮食组,每种膳食分别连续使用4周,间隔洗脱期4周,比较试验前后患者超氧化物歧化酶、脂质过氧化产物丙二醛和谷胱甘肽过氧化物酶含量的变化。结果:受试者依从性好,除1人因试验期间发现肿瘤而退出试验,42名志愿者按设计要求完成试验。膳食干预后低血糖指数饮食组和高血糖指数饮食组的超氧化物歧化酶活力分别升高了15.68%和21.33%,丙二醛水平分别下降23.94%和21.55%,谷胱甘肽过氧化物酶活力分别升高了15.74%和17.09%;干预后低血糖指数饮食组丙二醛下降水平与高血糖指数饮食组比较差异有显著性意义(P<0.05),而超氧化物歧化酶和谷胱甘肽过氧化物酶活性两组间差异无显著性意义(P>0.05)。结论:在控制总能量的基础上给予平衡膳食能够改善其氧化应激水平,采用低血糖指数食物有助于氧化应激水平的改善。  相似文献   
57.
Fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of pulmonary fibrosis. Mice lacking FGF2 have increased mortality and impaired epithelial recovery after bleomycin exposure, supporting a protective or reparative function following lung injury. To determine whether FGF2 overexpression reduces bleomycin‐induced injury, we developed an inducible genetic system to express FGF2 in type II pneumocytes. Double‐transgenic (DTG) mice with doxycycline‐inducible overexpression of human FGF2 (SPC‐rtTA;TRE‐hFGF2) or single‐transgenic controls were administered intratracheal bleomycin and fed doxycycline chow, starting at either day 0 or day 7. In addition, wild‐type mice received intratracheal or intravenous recombinant FGF2, starting at the time of bleomycin treatment. Compared to controls, doxycycline‐induced DTG mice had decreased pulmonary fibrosis 21 days after bleomycin, as assessed by gene expression and histology. This beneficial effect was seen when FGF2 overexpression was induced at day 0 or day 7 after bleomycin. FGF2 overexpression did not alter epithelial gene expression, bronchoalveolar lavage cellularity or total protein. In vitro studies using primary mouse and human lung fibroblasts showed that FGF2 strongly inhibited baseline and TGFβ1‐induced expression of alpha smooth muscle actin (αSMA), collagen, and connective tissue growth factor. While FGF2 did not suppress phosphorylation of Smad2 or Smad‐dependent gene expression, FGF2 inhibited TGFβ1‐induced stress fiber formation and serum response factor‐dependent gene expression. FGF2 inhibition of stress fiber formation and αSMA requires FGF receptor 1 (FGFR1) and downstream MEK/ERK, but not AKT signaling. In summary, overexpression of FGF2 protects against bleomycin‐induced pulmonary fibrosis in vivo and reverses TGFβ1‐induced collagen and αSMA expression and stress fiber formation in lung fibroblasts in vitro, without affecting either inflammation or epithelial gene expression. Our results suggest that in the lung, FGF2 is antifibrotic in part through decreased collagen expression and fibroblast to myofibroblast differentiation. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
58.
The mouse trigeminal (V) system undergoes significant postnatal structural and functional developmental changes. Histological modules (barrelettes, barreloids and barrels) in the brainstem, thalamus and cortex related to actively moved (whisking) tactile hairs (vibrissae) on the face allow detailed studies of development. High‐resolution [3H]2‐deoxyglucose (2DG) emulsion autoradiography with cytochrome oxidase histochemistry was used to analyze neuronal activity changes related to specific whisker modules in the developing and mature mouse V system provoked by passive (experimenter‐induced) and active (animal‐induced) displacements of a single whisker (D4). We tested the hypothesis that neuronal activity patterns change in relation to the onset of active touch (whisking) on postnatal day (P)14. Quantitative image analyses revealed: (i) on P7, when whisker‐like patterns of modules are clear, heightened 2DG activity in all appropriate modules in the brainstem, thalamus and cortex; (ii) on P14, a transitory activity pattern coincident with the emergence of whisking behavior that presages (iii) strong labeling of the spinal V subnucleus interpolaris and barrel cortex produced by single‐whisker‐mediated active touch in adults and (iv) at all above‐listed ages and structures, significant suppression of baseline activity in some modules surrounding those representing the stimulated whisker. Differences in activity patterns before and after the onset of whisking behavior may be caused by neuronal activity induced by whisking, and by strengthening of modulatory projections that alter the activity of subcortical inputs produced by whisking behavior during active touch.  相似文献   
59.
60.
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