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   697篇
  免费   50篇
耳鼻咽喉   1篇
儿科学   35篇
妇产科学   8篇
基础医学   91篇
口腔科学   32篇
临床医学   28篇
内科学   173篇
皮肤病学   35篇
神经病学   34篇
特种医学   11篇
外科学   115篇
综合类   5篇
预防医学   14篇
眼科学   2篇
药学   44篇
中国医学   1篇
肿瘤学   118篇
  2023年   5篇
  2022年   5篇
  2021年   9篇
  2020年   3篇
  2019年   8篇
  2018年   14篇
  2017年   11篇
  2016年   22篇
  2015年   22篇
  2014年   32篇
  2013年   20篇
  2012年   39篇
  2011年   38篇
  2010年   27篇
  2009年   22篇
  2008年   39篇
  2007年   45篇
  2006年   39篇
  2005年   29篇
  2004年   32篇
  2003年   32篇
  2002年   26篇
  2001年   27篇
  2000年   36篇
  1999年   19篇
  1998年   13篇
  1997年   8篇
  1996年   7篇
  1994年   5篇
  1993年   2篇
  1992年   7篇
  1991年   14篇
  1990年   9篇
  1989年   7篇
  1988年   9篇
  1987年   9篇
  1986年   6篇
  1985年   4篇
  1984年   3篇
  1983年   6篇
  1980年   3篇
  1978年   5篇
  1977年   6篇
  1971年   2篇
  1970年   2篇
  1969年   3篇
  1968年   1篇
  1967年   5篇
  1966年   2篇
  1963年   1篇
排序方式: 共有747条查询结果,搜索用时 15 毫秒
41.
Liposidomycin, a potent inhibitor of bacterial peptidoglycan biosynthesis, represents the main component of a group of over 24 closely related, fatty acyl nucleoside antibiotics produced by Streptomyces. Exogeneously supplied myristic acid or palmitic acid resulted in the almost exclusive production of liposidomycin C-(III) and/or M-(III). Exogeneously supplied [1-13C]-palmitic acid was incorporated directly into liposidomycin M-(III) as judged by the FAB-MS and 13C NMR spectra.  相似文献   
42.
Sotos syndrome is an overgrowth disorder of unknown etiology associated with a high incidence of congenital heart defects. Of 60 patients with Sotos syndrome treated in our hospital, 6 had congenital heart defects. We describe a case of successful total cavopulmonary connection at 30 months of age in a patient having pulmonary atresia with intact ventricular septum and a patent ductus arteriosus who had walking disability. The postoperative course was uneventful.  相似文献   
43.
We previously reported a novel monoclonal antibody KOR-SA3544 which predominantly reacted with a surface antigen (sSA3544) expressed on Philadelphia chromosome (Ph1)-positive acute lymphoblastic leukemia (ALL). In the present study, we demonstrate that the antibody specifically recognized nonspecific cross-reacting antigen (NCA)-50/90 (CD66c), one of the carcinoembryonic antigen (CEA)-related glycoproteins encoded by a member of the CEA gene family. In addition, we show that the SA3544 antigen (NCA-50/90) was invariably expressed in cytoplasm of all of the human leukemic cell lines examined (sSA3544-positive B-lymphoid two, sSA3544-negative T or B-lymphoid and non-lymphoid 24) regardless of the presence or absence of surface expression of this antigen. Immunoelectromicroscopic examination revealed that the cytoplasmic antigen was mainly present in granules in sSA3544-positive leukemia cells, whereas it was diffusely present in cytosol in sSA3544-negative leukemia cells. Thus, among members of the CEA family, NCA-50/90 was first demonstrated to be expressed not only on the surface of some leukemia cells, but also in cytoplasm of various types of leukemia cells.  相似文献   
44.
Diffuse large B cell lymphoma (DLBL) constitutes the greatest percentage of adult non-Hodgkin's lymphomas and represents a diverse spectrum of lymphoid neoplasms. Clinicopathologic, phenotypic and genotypic findings were correlated and compared for 63 DLBL cases to investigate whether they represent clinically relevant subtypes. They were all cyclin D1 negative and were phenotypically divided into three groups, ie group I (CD5+ type, n=11), group II (CD5- CD10+ type, n=19), and group III (CD5- CD10- type, n=33). Data were correlated by observing the respective gene rearrangement and expression of BCL2 and BCL6. In clinical aspects, the group I cases demonstrated a significantly inferior survival than those of the other two groups (log-rank test, P = 0.016). Although rearrangement of BCL2 and BCL6 did not show any inclination to a specific subgroup, the immunohistochemical detection of BCL2 was less frequent, at a statistically significant level (P=0.011), in group II (50%) than in group I (82%) and III (82%) cases. This appears to confirm the unique aspect of the CD5- CD10+ type DLBL, indicating a certain relationship with the normal germinal center cells which usually lack BCL2 expression. The BCL6 protein expression was detected in most of the present DLBL cases (92%) irrespective of this grouping. These data suggest that the phenotypic delineation by the detection of CD5 and CD10 will improve our understanding of DLBL and be helpful in a future subgrouping of DLBL.  相似文献   
45.
46.
47.
For successful tissue engineering, neovascularization of the implanted tissue is critical. Factors generated by endothelial cells are also considered crucial for the process of osteogenesis. The direct effects of supplementing tissue engineered constructs with cultured endothelial progenitor cells (EPCs) for enhancing bone regeneration have not been reported. In this study, we investigated the potential of EPCs to facilitate neovascularization in implants and evaluated their influence on bone regeneration. The influence of EPC soluble factors on osteogenic differentiation of mesenchymal stem cells (MSCs) was tested by adding EPC culture supernatant to MSC culture medium. To evaluate the influence of EPCs on MSC osteogenesis, canine MSCs-derived osteogenic cells and EPCs were seeded independently onto collagen fiber mesh scaffolds and co-transplanted to nude mice subcutaneously. Results from coimplant experiments were compared to implanted cells absent of EPCs 12 weeks after implantation. Factors from the culture supernatant of EPCs did not influence MSC differentiation. Coimplanted EPCs increased neovascularization and the capillary score was 1.6-fold higher as compared to the MSC only group (p < 0.05). Bone area was also greater in the MSC + EPC group (p < 0.05) and the bone thickness was 1.3-fold greater in the MSC + EPC group than the MSC only group (p < 0.05). These results suggest that soluble factors generated by EPCs may not facilitate the osteogenic differentiation of MSCs; however, newly formed vasculature may enhance regeneration of tissue-engineered bone.  相似文献   
48.
We encountered a patient with a history of juvenile cerebral infarction with an unknown cause in whom a mass adhering to the aortic valve (AV) surface was observed on echocardiography performed upon the development of heart failure. Mild AV stenosis (AS) with moderate regurgitation was noted, and valve repair was applied. It was found during surgery that the AV was a bicuspid valve (BAV) without calcification, and the mass was an organized thrombus. Thrombus formation on the AV with severe AS in BAV has been reported, but the organic lesion in the AV was mild in this patient.  相似文献   
49.
Lymph node metastasis is a major prognostic factor for esophageal squamous cell carcinoma (ESCC). In recent years, endoscopic mucosal resection (EMR) has been developed with excellent results for the treatment of the superficial ESCC. To make the EMR treatment successful, it is important to establish a good indicator to identify ESCC patients at a high risk of lymph node metastasis. In this study, we examined clinicopathological and immunohistochemical factors to investigate the factors involved in lymph node metastasis of ESCC invading to the submucosal layer (sm-ESCC). Surgical specimens from 84 sm-ESCC patients were examined. Among 84 sm-ESCC patients, 33 (39.3%) had lymph node metastases. Clinicopathologically, tumor depth, lymphatic invasion and blood vessel invasion showed significant correlations with lymph node metastasis by univariate analysis. Tumor depth and lymphatic invasion showed significant correlations by multivariate analysis of these factors. Immunohistochemically, P53 accumulation was observed in 45 cases (53.6%), cyclin D1 overexpression in 25 (29.8%), and pRB in 65 (77.4%). P53 accumulation, cyclin D1 overexpression and MIB-1 Labeling Index were significantly associated with lymph node metastasis by univariate analysis, and P53 accumulation showed a significant correlation with lymph node metastasis by multivariate analysis. Among tumor depth, lymphatic invasion and P53 accumulation, tumor depth and lymphatic invasion were significantly correlated with lymph node metastasis ( P =0.0023 and P =0.0092, respectively) by multivariate analysis. These data suggest that tumor depth and lymphatic invasion can be considered as good indicators for lymph node metastasis among patients with sm-ESCC. In addition, P53 accumulation could be helpful to identify the patients who need additional treatment after EMR.  相似文献   
50.
Summary An IgM antibody cytotoxic to normal human lymphocytes was found in 46.2% (male: 61.5%; female: 30.8%) of sera from chronic schizophrenics by means of a complement-dependent cytotoxicity test. The relationship between this antibody and the immunological manifestations of schizophrenia is discussed.  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