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   428篇
  免费   28篇
  国内免费   13篇
儿科学   23篇
基础医学   44篇
口腔科学   3篇
临床医学   60篇
内科学   84篇
皮肤病学   2篇
神经病学   5篇
特种医学   6篇
外科学   4篇
综合类   70篇
预防医学   3篇
眼科学   4篇
药学   27篇
中国医学   13篇
肿瘤学   121篇
  2023年   6篇
  2022年   3篇
  2021年   5篇
  2020年   8篇
  2019年   7篇
  2018年   7篇
  2017年   7篇
  2016年   8篇
  2015年   13篇
  2014年   16篇
  2013年   13篇
  2012年   12篇
  2011年   24篇
  2010年   12篇
  2009年   9篇
  2008年   7篇
  2007年   20篇
  2006年   14篇
  2005年   21篇
  2004年   12篇
  2003年   8篇
  2002年   21篇
  2001年   11篇
  2000年   5篇
  1999年   8篇
  1998年   12篇
  1997年   7篇
  1996年   10篇
  1995年   10篇
  1994年   13篇
  1993年   15篇
  1992年   16篇
  1991年   5篇
  1990年   10篇
  1989年   13篇
  1988年   5篇
  1987年   8篇
  1986年   5篇
  1985年   12篇
  1984年   14篇
  1983年   7篇
  1982年   4篇
  1981年   7篇
  1980年   3篇
  1979年   4篇
  1978年   3篇
  1977年   4篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
排序方式: 共有469条查询结果,搜索用时 15 毫秒
1.
目的采集手术切除未经培养的骨肉瘤标本,研究肿瘤中成骨细胞的分化及其与临床因素的关系。方法观察骨肉瘤中成骨细胞相关基因表达的频率、特异性,以及骨肉瘤成骨细胞表型与生物学行为的关系。应用RT-PCR方法研究48例骨肉瘤标本的碱性磷酸酶(ALP)、骨钙素(OC)和骨桥蛋白(ON)的mRNA转录。磷酸甘油酸激酶(PGK)被用于内参照。结果在大多数骨肉瘤标本中可以发现ALP或OC的mRNA转录(分别为93.75%,79.17%)。在所有的肉瘤检测中均可发现ON的mRNA转录。在骨肉瘤的成骨细胞亚型中可见到ALP和OC的高水平表达。肺转移瘤OC的mRNA表达弱于原发灶。肿瘤细胞有高水平OC表达的病例组有较高的生存率(P=0.045)。结论OC是目前最好的成骨细胞特异性标记物,将来可能用于检测骨肉瘤患者外周血中循环的肿瘤细胞。  相似文献   
2.
Summary In this study the technique of labelling the cell membrane with DPH fluorescence polarization was used to observe the membrane fluidity of B lymphocytic cell lines and tonsillar cells from healthy persons; the modulation effect on membrane-fluidity induced by McAbs against isotypic and idiotypic determinants of IgM from patients with leukemia was studied as well. The expression of the corresponding isotypic and idiotypic determinants of IgM on the cell membrane was determined. The results show that the membrane fluidity of leukemic cell lines is remarkably higher than that of tonsillar cells from healthy persons, and McAbs against isotypic determinants of leukemic IgM can enhance the membrane fluidity of all kinds of cells mentioned above. However, the anti-idiotypic monoclonal antibody increased only the membrane fluidity of leukemic cell lines. These results indicated that there was a close relationship between the effect of McAbs on cell membrane fluidity and the expression of corresponding isotypic and idiotypic determinants of IgM on the cell membrane.  相似文献   
3.
急性髓系白血病血管内皮生长因子表达与预后的研究   总被引:1,自引:0,他引:1  
目的 :观察人白血病细胞系血管内皮生长因子 (VEGF)表达水平 ,研究急性髓系白血病 (AML)患者血清VEGF表达水平与预后的关系。方法 :采用酶联免疫吸附法 (ELISA)对 4 9例初治、10例复发AML患者血清及人白血病细胞系U937、K5 6 2、HL - 6 0、TF - 1和NB4培养上清液 (4 8小时 )VEGF表达水平进行检测。结果 :五种人白血病细胞系培养上清液中均测到VEGF高表达。 4 9例初治、10例复发AML患者的血清VEGF表达水平分别为 2 0 1 17± 110 93pg ml和 2 32 5 9± 118 6 2pg ml,均明显高于正常对照组 (12 5 6 2± 4 5 4 3pg ml;p <0 0 5 )。初治AML患者中VEGF高表达组 (>2 0 1 17pg ml)完全缓解 (CR)率为 4 8% ,低表达组 (<2 0 1 17pg ml)CR率为 77% ,两者比较差异显著 (p<0 0 5 )。结论 :血管内皮生长因子在刺激白血病细胞增殖、迁移中发挥重要作用。AML患者血清VEGF水平与预后具相关性  相似文献   
4.
按种P_(388)白血病患鼠腹水后第3d,小鼠胸腺哺育细胞内的淋巴细胞,酸性磷酸酶和β-葡萄糖苷酸酶阳性率显著增加,而α-醋酸萘酯酶阳性率则下降。胸腺内胸腺细胞上述3种酶细胞化学反应阳性率均显著增加,但胸腺组织结构未见异常。淋巴结和脾脏亦未见异常变化。接种后第9d,患鼠胸腺、淋巴结和脾脏均见白血病细胞浸润、出血和细胞变性等病变,正常结构被破坏,其中淋巴细胞3种酶细胞化学反应的阳性率均显著增加。此时很难从胸腺分离出胸腺哺育细胞。本文结果提示,胸腺和胸腺哺育细胞与这种白血病的发生有密切关系。  相似文献   
5.
Summary The enzyme inosinic acid dehydrogenase (EC 1.2.1. [14]) was measured and partially purified (10- to 15-fold) from normal and leukemic leukocytes. From the normal blood cells, the highest activities could be detected in lymphocytes and bone marrow cells. Dependent on the blast cell count, the leukemic IMP dehydrogenase had a higher mean specific activity than the enzymes of fractionated, immature bone marrow cells, or normal granulocytes. The partially purified enzymes from the various blood cells were apparently identical; they exhibited hyperbolic substrate saturation kinetics and were inhibited by a number of purine nucleotides. For the leukemic blast cell enzyme, theK m values for the substrates, IMP and NAD+, were 28±11; 227±98 µM, and 34±10; 240±67 µM for the partially purified enzyme from normal, immature bone marrow cells.The hypoxanthine-guanine and adenine phosphoribosyltransferase activities increased in the leukemic cells when compared with mature granulocytes, but nearly always showed similar activities when compared with the fractionated bone marrow cells. Only one of the 30 investigated leukemic patients exhibited a marked decrease in hypoxanthine phosphoribosyltransferase activity of 0.5 nmol/mg/h. The phosphoribosyltransferase-specific activities of the leukemic cells are more variable than for the normal ones and no correlation of enzyme activities and blast cell count was apparent.
Abbreviations A-PRT adenine phosphoribosyltransferase - HG-PRT hypoxanthine-guanine phosphoribosyltransferase - PRPP 5-phosphoribosyl-1-pyrophosphate - ALL acute lymphocytic leukemia - AML acute myelogenous leukemia - CLL chronic lymphatic leukemia - CML chronic myelogenous leukemia - AMMOL acute myelomonocytic leukemia This study was supported by the Deutsche forschungsgemeinschaft Be 458/4  相似文献   
6.
Summary Cyclophosphamide (CPA) is widely used against leukemic and lymphoproliferative diseases, but in vitro studies on response to this agent so far have been limited to instable derivatives with poor galenic properties. ASTA Z 7557 is a newly synthesized activated cyclophosphamide that circumvents the need for hepatic activation and has good stability. The critical cytotoxic lesions after exposure to bifunctional alkylating agents presumably are DNA interstrand crosslinks (ISC). We have, therefore, examined the formation and apparent removal of ISC after in vitro treatment with ASTA Z 7557 by use of the highly sensitive alkaline elution technique. Survival of murine L1210 cells was determined after 1 hour in vitro exposure with a D 37 value of 5.7 g/ml (from the initial shoulder part of the survival curve) and a Do value of 1.5 g/ml (from the exponential part of the curve). Previous labelling of L1210 cells by 125IUdR simplified the alkaline elution procedure but there was some cytotoxicity of the radiochemical itself with a reduction of cloning efficiency from 77% to 61 %. The maximum of ISC was observed at 6 h after initiation of treatment with much of the damage apparently removed at 24 h. The simultaneous presence of DNA single strand breaks (SSB), however, confounds the analysis of DNA damage at 24 h and early cytolysis and unaided death of human lymphocytes often preclude the analysis of macromolecular damage at this time. Human peripheral blood cells isolated from patients with leukemic or lymphoproliferative diseases showed a remarkable heterogeneity with regard to the formation of ISC at 3 h. Thus, analysis of macromolecular damage may become an additional prognostic factor for response to CPA beyond the morphologic classification of these diseases.  相似文献   
7.
白血病细胞线粒体超微结构及其蛋白质双向电泳分析   总被引:4,自引:0,他引:4  
探讨白血病细胞线粒体(mt)形态、结构和功能的异常与mt蛋白组分变化间的可能的关系。方法采用离心法分离纯化了可移植性小鼠腹水型白血病细胞(L7811)及正常615纯系小鼠胸腺细胞线粒体,对其超微结构进行了电镜观察。结果对它们各自蛋白质双向电泳图谱分析后发现在PH4.5~6.5,MW15~35KD范围内正常对照有8个蛋白质斑点在L7811l白血病细胞线粒体电泳图谱相应位置未观察到,而在PH6左右、MW10~17KD区域内白血病样品有3个蛋白质斑点,在正常对照的电泳图谱相应区域也未观察到。结论白血病细胞与正常对照细胞相比线粒体在超微结构和蛋白质组成上均有明显差异。  相似文献   
8.
Hematologic malignancies most commonly spread to the central nervous system via leptomeningeal infiltration. We present a unique case of a woman who presented with a right parietal mass as the initial manifestation of B cell acute lymphocytic leukemia. Because the diagnosis was unclear at the time of presentation she underwent surgical debulking of the mass prior to treatment with chemotherapy. Unfortunately, she relapsed several months after treatment and ultimately entered hospice care. We review the literature surrounding management considerations in patients with intracranial leukemic involvement.  相似文献   
9.
Diallyl trisulfide (DATS), a chemopreventive dietary constituent and extracted from garlic, has been shown to against cultured many types of human cancer cell liens but the fate of apoptosis in murine leukemia cells in vitro and immune responses in leukemic mice remain elusive. Herein, we clarified the actions of DATS on growth inhibition of murine leukemia WEHI‐3 cells in vitro and used WEHI‐3 cells to generate leukemic mice in vivo, following to investigate the effects of DATS in animal model. In in vitro study, DATS induced apoptosis of WEHI‐3 cells through the G0/G1 phase arrest and induction of caspase‐3 activation. In in vivo study DATS decreased the weight of spleen of leukemia mice but did not affect the spleen weight of normal mice. DATS promoted the immune responses such as promotions of the macrophage phagocytosis and NK cell activities in WEHI‐3 leukemic and normal mice. However, DATS only promotes NK cell activities in normal mice. DATS increases the surface markers of CD11b and Mac‐3 in leukemia mice but only promoted CD3 in normal mice. In conclusion, the present study indicates that DATS induces cell death through induction of apoptosis in mice leukemia WHEI‐3 cells. DATS also promotes immune responses in leukemia and normal mice in vivo. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1343–1353, 2015.  相似文献   
10.

Introduction

During routine blood measurements using an automated hematology analyzer, two easily confused types of suspect flags related to lymphocytes often appear: atypical and immature lymphocytes. The aim of this study was to investigate the correlation of high fluorescence cell (HFC) parameter and lymphocyte flags determined from an automated hematology analyzer.

Methods

A total of 93 patients affected by various pathologic conditions (viral infection, immunological disease, oncological disease and tumor) were divided into an “atypical lymphocytes” group (“atypical” for short), an “immature lymphocytes/blasts” flag group (abnormal), a mixed‐flag group that includes “atypical lymphocytes” (mixed), and a non‐flag group (non‐flag).

Results

The numbers of HFCs in the atypical, abnormal, mixed, and non‐flag groups were 1.8% (0.9%‐5.5%), 0.7% (0.1%‐5.0%), 2.3% (1.2%‐5.0%), and 0.8% (0.7%‐1.2%), respectively. The HFCs of “atypical” appeared as a separate cluster with clear boundaries. The HFCs of “abnormal” as an unclear boundaries, and it was difficult to accurately distinguish between the HFCs from the immature lymphocytes and the normal lymphocytes. The lower limit of HFC when the atypical lymphocyte flag appeared was 0.04 × 109/L. The number of HFCs was similar to atypical lymphocytes detected by microscopy and CD19+CD20CD27++ cells by flow cytometry at 78% and 76%, respectively. The number of HFCs detected in “atypical” and CD19+CD20CD27++ cells showed good consistency (r = .715), whereas the consistency was poorest for “abnormal” (r = .176).

Conclusion

It demonstrates that HFCs reflects atypical lymphocytes better than immature lymphocytes/blasts.
  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