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   1081篇
  免费   59篇
  国内免费   9篇
耳鼻咽喉   23篇
儿科学   16篇
妇产科学   24篇
基础医学   172篇
口腔科学   98篇
临床医学   110篇
内科学   212篇
皮肤病学   10篇
神经病学   115篇
特种医学   41篇
外国民族医学   1篇
外科学   147篇
综合类   5篇
预防医学   53篇
眼科学   23篇
药学   64篇
中国医学   2篇
肿瘤学   33篇
  2023年   5篇
  2022年   20篇
  2021年   35篇
  2020年   19篇
  2019年   31篇
  2018年   25篇
  2017年   15篇
  2016年   28篇
  2015年   30篇
  2014年   48篇
  2013年   50篇
  2012年   95篇
  2011年   108篇
  2010年   49篇
  2009年   37篇
  2008年   64篇
  2007年   47篇
  2006年   71篇
  2005年   54篇
  2004年   50篇
  2003年   44篇
  2002年   40篇
  2001年   11篇
  2000年   18篇
  1999年   10篇
  1998年   3篇
  1997年   8篇
  1996年   5篇
  1995年   4篇
  1993年   3篇
  1992年   5篇
  1991年   10篇
  1990年   5篇
  1989年   13篇
  1988年   9篇
  1987年   7篇
  1986年   9篇
  1985年   4篇
  1984年   6篇
  1983年   3篇
  1982年   5篇
  1981年   4篇
  1980年   3篇
  1979年   6篇
  1976年   5篇
  1975年   4篇
  1973年   3篇
  1971年   2篇
  1970年   2篇
  1967年   2篇
排序方式: 共有1149条查询结果,搜索用时 112 毫秒
1.
2.
We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5 mm) were placed in the frontal calvarial region of nine adult pigs. The animals were sacrificed at 2, 4 and 8 weeks to evaluate the implant incorporation microradiographically. The clinical outcome and patient satisfaction of implant-retained prostheses were evaluated in a group of 10 patients with facial defects by using clinical assessment and standardized questionnaires for patients and relatives. In the prospective clinical study 33 identical modified implants for extraoral anchorage were placed for the fixation of various prostheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial and observed over a follow-up period of 34 months. The bone-implant contact in the animal experiment reached 31% (+/-2) at 2 weeks, 39% (+/-1) after 4 weeks and 51% (+/-5) at 8 weeks. In the clinical trial, no implants were lost and all implants remained osseointegrated as confirmed clinically and radiographically, providing a stable prosthetic restoration. The analysis of the questionnaire indicates an improvement of the quality of life of patients with respect to aesthetic and psychological well-being. The results demonstrate that extraoral implants not only achieve sufficient osseointegration but also show good clinical handling and easy fixation possibilities for prosthetic anchorage.  相似文献   
3.
4.
INTRODUCTION: The aim of the study was to evaluate the role of apoptosis, proliferation markers, volume density of interstitium, and myofibril volume fraction for the prognosis in patients with end-stage dilated cardiomyopathy (DCM). METHODS: Endomyocardial biopsy was performed during open-heart surgery in 56 patients with end-stage DCM. Patients were divided into two groups, one group with shorter survival (24+/-9 months, mean+/-S.D.) and another group with survival of more than 7 years after operation. The TUNEL method was used for the detection of apoptosis, and immunohistochemical methods were used for the evaluation of inhibitor of apoptosis (bcl-2) and proliferation markers (PCNA and Ki-67). RESULTS: The increased percentage of apoptotic myocytes, decreased expression of bcl-2, and decreased expression of PCNA and Ki-67 antigen was found in the group with early mortality compared to that with longer survival. Myofibril volume fraction was lower and volume density of interstitium was higher in the group with early mortality compared to that with longer survival. CONCLUSION: Apoptosis, bcl-2 expression, and proliferation activity of myocytes, myofibril volume fraction, and volume density of interstitial tissue might be useful in predicting the prognosis (progressive vs. nonprogressive form) of patients with heart failure due to DCM.  相似文献   
5.
The kinetics of gene expression associated with the development of cutaneous graft-versus-host disease (GVHD) were examined in a mouse model of MHC-matched allogeneic hematopoietic stem cell transplantation. Ear skin was obtained from recipient mice with or without GVHD between 7 and 40 days after transplantation for histopathological analysis and gene expression profiling. Gene expression patterns were consistent with early infiltration and activation of CD8(+) T and mast cells, followed by CD4(+) T, natural killer, and myeloid cells. The sequential infiltration and activation of effector cells correlated with the histopathological development of cutaneous GVHD and was accompanied by up-regulated expression of many chemokines and their receptors (CXCL-1, -2, -9, and -10; CCL-2, -5, -6, -7, -8, -9, -11, and -19; CCR-1 and CCR-5), adhesion molecules (ICAM-1, CD18, Ly69, PSGL-1, VCAM-1), molecules involved in antigen processing and presentation (TAP1 and TAP2, MHC class I and II, CD80), regulators of apoptosis (granzyme B, caspase 7, Bak1, Bax, and BclII), interferon-inducible genes (STAT1, IRF-1, IIGP, GTPI, IGTP, Ifi202A), stimulators of fibroblast proliferation and matrix synthesis (interleukin-1beta, transforming growth factor-beta1), and markers of keratinocyte proliferation (keratins 5 and 6), and differentiation (small proline-rich proteins 2E and 1B). Many acute-phase proteins were up-regulated early in murine cutaneous GVHD including serum amyloid A2 (SAA2), SAA3, serpins a3g and a3n, secretory leukocyte protease inhibitor, and metallothioneins 1 and 2. The kinetics of gene expression were consistent with the evolution of cutaneous pathology as well as with current models of disease progression during cutaneous GVHD.  相似文献   
6.
Loss of genetic material from chromosome arm 8p occurs frequently in human breast carcinomas, consistent with this region of the genome harboring one or more tumor suppressor genes (TSGs). We used the complementary techniques of microsatellite-based LOH, high-density FISH, and conventional CGH on 6 breast cancer cell lines (MCF7, SKBR3, T47D, MDA MB453, BT549, and BT474) to investigate the molecular cytogenetic changes occurring on chromosome 8 during tumorigenesis, with particular emphasis on 6 potential TSGs on 8p. We identified multiple alterations of chromosome 8, including partial or complete deletion of 8p or 8q, duplication of 8q, and isochromosome 8q. The detailed FISH analysis showed several complex rearrangements of 8p with differing breakpoints of varying proximity to the genes of interest. High rates of LOH were observed at markers adjacent to or within PCM1, DUSP4/MKP2, NKX3A, and DLC1, supporting their status as candidate TSGs. Due to the complex ploidy status of these cell lines, relative loss of 8p material detected by CGH did not always correlate with microsatellite-based LOH results. These results extend our understanding of the mechanisms accompanying the dysregulation of candidate tumor suppressor loci on chromosome arm 8p, and identify appropriate cellular systems for further investigation of their biological properties.  相似文献   
7.
The case of a 77-year-old man in whom a large digital ulcer with undermined edges was due to cutaneous infection byCryptococcus neoformans varietyneoformans serotype D, probably following direct inoculation, is reported. Long-term steroid treatment for chronic obstructive pulmonary disease may have been a risk factor. A 12-day course of intravenous amphotericin B at a cumulative dose of 750 mg, followed by oral fluconazole at a daily dose of 600 mg for six weeks, resulted in healing of the skin lesion. Manifestations of primary cutaneous cryptococcosis in immunocompetent or immunocompromised patients are reviewed  相似文献   
8.
As a crucial step towards understanding the mechanism of localisation of radiopharmaceuticals in specific target organs, the interaction of the radiopharmaceuticals 99mTc-DMS and 99Tc-DMS with blood serum proteins was studied. The interaction of 99mTc-DMS radiopharmaceutical was examined from two aspects: total protein binding as well as specificity of binding to certain classes of proteins.After in vitro labelling of human sera with 99mTc-DMS, the following values of bound radioactivity to total serum proteins were determined: 65%±3.2% by gel-filtration chromatography; 72%±4.6% by dialysis; while on the basis of precipitation by perchloric and trichloroacetic acid 72.7%±6.8% and 71%±2.3%, respectively. Distribution of 99mTc-DMS or 99Tc-DMS among serum proteins was analysed by agarose gel electrophoresis of the sera at pH 8.6 after in vivo and in vitro labelling of human sera with 99m-Tc-DMS, while the same analysis was performed with 99Tc-DMS complex after in vitro labelling of human and rat sera as well as after in vivo application to the rats.The results obtained demonstrate that carrier serum proteins investigated by agarose gel electrophoresis were in the migration zone of 2-, 1- and 1-globulins, whereas the radioactivity found in the serum albumin zone was negligible. Interaction of both Tc-DMS complexes with proteins was very similar, and this conclusion was in good correlation with our previously obtained results in investigations concerning the biochemical behaviour of these complexes.  相似文献   
9.
The actions of BW B70C, an orally available, biologically persistent and selective inhibitor of arachidonic acid 5-lipoxygenase, have been examined in two systems of anaphylaxis in actively sensitised guinea-pigsin vivo.In anaesthetised, artificially ventilated animals pretreated with mepyramine and indomethacin to leave only the “peptidoleukotriene-dependent” component (leukotrienes C4, D4 and E4) of the anaphylactic response, direct inhalation of nebulised, allergen resulted in a slowly developing bronchoconstriction which was prevented in a dose-dependent manner, by BW B70C (2–50 mg/kg p.o.) administered 1 or 6 h before challenge.In conscious animals fasted overnight and then pretreated with mepyramine to prevent death due to acute bronchial anaphylaxis, exposure to nebulised, allergen produced slight respiratory symptoms. When blood and lung samples were analysed 4–48 h after allergen provocation a sustained leukocytosis and pulmonary eosinophil accumulation were observed. In contrast, in food-replete conscious animals, the early respiratory symptoms were still observed upon allergen inhalation, but no significant blood leukocytosis or accumulation of eosinophils in the lungs occurred subsequently.The eosinophil influx induced by allergen in fasted animals was assessed both by histological examination and determination of tissue peroxidase content, two measures which demonstrated reasonable agreement. Administration of a single dose of BW B70C (10 mg/kg p.o.) 1 h prior to allergen challenge did not affect the subsequent eosinophil infiltration 24 h later, but 20 mg/kg given in divided doses (?1 and +12 h) produced 67% inhibition of cell accumulation. A single dose of 50 mg/kg (?1 h) had a similar effect (78% inhibition). The potent glucocorticosteroid betamethasone was used as a reference compound, and 4 mg/kg given as a divided dose (?1 and +7) fully inhibited lung inflammation assessed 24 h after provocation with allergen. BW B70C inhibited both acute and allergic bronchoconstriction and late-phase eosinophil accumulation subsequent to allergen inhalation in guinea-pigs. In view of the apparent requirement for sustained plasma levels of BW B70C in order to prevent late-phase eosinophil recruitment to the lung after a single challenge with allergen, it is unclear whether inhibition of 5-lipoxygenase underlies the observed anti-eosinophil accumulation effects of the compound, but the anti-bronchoconstrictor effects are consistent with the known inhibitory activity of BW B70C against 5-lipoxygenase.  相似文献   
10.
Sixty 20-day-old male rats were divided into 4 groups: controls (group 1), partly immobilized mandible with a chincup-type appliance (group 2) and completely immobilized mandible without (group 3) or with (group 4) a chincup-type appliance. After 4 weeks the rats were killed and 3 parameters were measured: number of 3H-thymidine labelled cells in the condylar cartilage. "Stutzmann's angle" and length of the mandible. The growth rate of the condylar cartilage and the lengthening of the mandible were both smaller than in the controls. The chincup treatment was much more efficient when the mandible was completely immobilized than when it was only partly immobilized.  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