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   904篇
  免费   19篇
  国内免费   16篇
耳鼻咽喉   1篇
儿科学   19篇
妇产科学   1篇
基础医学   318篇
口腔科学   5篇
临床医学   54篇
内科学   153篇
皮肤病学   51篇
神经病学   31篇
特种医学   6篇
外科学   13篇
综合类   58篇
预防医学   75篇
眼科学   2篇
药学   91篇
中国医学   31篇
肿瘤学   30篇
  2023年   1篇
  2022年   3篇
  2021年   9篇
  2020年   6篇
  2019年   32篇
  2018年   40篇
  2017年   33篇
  2016年   17篇
  2015年   17篇
  2014年   59篇
  2013年   64篇
  2012年   46篇
  2011年   71篇
  2010年   66篇
  2009年   48篇
  2008年   49篇
  2007年   57篇
  2006年   39篇
  2005年   50篇
  2004年   33篇
  2003年   51篇
  2002年   18篇
  2001年   19篇
  2000年   13篇
  1999年   14篇
  1998年   12篇
  1997年   11篇
  1996年   9篇
  1995年   3篇
  1994年   10篇
  1993年   4篇
  1991年   3篇
  1990年   2篇
  1989年   2篇
  1988年   3篇
  1987年   2篇
  1985年   5篇
  1984年   9篇
  1983年   1篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
排序方式: 共有939条查询结果,搜索用时 711 毫秒
1.
丙型肝炎患者外周血单核细胞中丙型肝炎病毒复制的研究   总被引:2,自引:0,他引:2  
9例临床诊断为丙型肝炎患者,研究其外周血单核细胞中HCVRNA的存在及复制。9例患者血清标本抗-HCV及HCVRNA均为阳性,采用高敏感的逆转录一套式PCR法测定其外周血单核细胞中HCV正、负链RNA,结果9例患者外周血单核细胞中7例HCV正链RNA阳性,3例HCV负链RNA阳性,证实部分丙肝患者外周血单核细胞中存在HCV的复制,表明肝细胞并非为HCV感染与复制的唯一场所。  相似文献   
2.
目的 研究慢性乙型肝炎患者PBMC和活检肝组织的APOBEC3G(A3G)mRNA表达状况并探讨两者之间的相关性;研究A3G mRNA转录表达水平与血清HBV DNA、ALT、PT水平及乙型肝炎肝组织学活动度Knodell计分的相关性.方法 采用实时荧光相对定苗RT-PCR的方法 检测45例慢性乙型肝炎患者PBMC及肝组织中A3G mRNA的表达水平,同时采用实时荧光定量PCR方法 检测血清HBV DNA;常规检测TBil、ALT、PT及乙型肝炎肝组织学活动度Knodell计分.同时设15例健康体检者为阴性对照组.结果 ①慢性乙型肝炎患者PBMC、肝组织均表达A3G mRNA.PBMC A3G mRNA表达水平与活检肝组织A3G mRNA表达呈正相关(r=0.457,P<0.05);②PBMC A3G mRNA与肝组织炎症活动度呈负相关(r=-0.441,P<0.05);③PBMC A3G表达水平与HBV DNA呈正相关(r=0.299,P<0.05),与TBil、ALT、PT无相关性.结论 本组研究显示:①体内研究慢性乙型肝炎患者A3G mRNA抗HBV作用,可首选外周血作为临床适用样本.②慢性乙型肝炎患者PBMC A3G mRNA水平可预测其肝组织损害程度,PBMC A3G mRNA水平越高,肝组织损害越轻.  相似文献   
3.
目的探讨GATA-3及Th2细胞因子IL-4与多发性肌炎(PM)/皮肌炎(DM)的关系。方法用RT-PCR方法检测PM/DM患者外周血单个核细胞(PBMC)中GATA-3、IL-4的mRAN表达,并与正常健康人进行比较。结果PM、DM组中GATA-3mRNA表达阳性率(85.7%,86.4%)均高于正常对照组(25%)(P<0.05);PM、DM组GATA-3的表达强度(0.268,0.411)均高于正常对照组(0.000)(P<0.05);皮肌炎IL-4mRNA的表达强度(0.251)高于正常对照组(0.000)(P<0.05);GATA-3与IL-4的表达强度呈正相关(r=0.475,P<0.05)。结论皮肌炎的Th2细胞过度分化及体液免疫增强可能与GATA-3表达增强有关。  相似文献   
4.
The purpose of this study was to investigate the antiproliferative activity of 2,3,9-trimethoxypterocarpan, a known pterocarpan with cytotoxic activity against many tumor cell lines, in a panel of four leukemia cell lines (HL-60, Molt-4, Jurkat, and K562) and on human peripheral blood mononuclear cells (PBMC). The pterocarpan showed IC50 ranging from 0.1 to 0.5 μg/ml at leukemic cells after 72 h of incubation, with K562 being the most resistant cell line. This compound seemed to be selective to tumor cell lines, since at a concentration of 10 μg/ml after 72 h, it only reduced 19% of viable peripheral mononuclear cells.  相似文献   
5.
6.

Background

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

Objectives

Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.

Methods

Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).

Results

Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+T-bet+ CD57+ cells of both patients and healthy donors were CD28nullCD27nullCD127null. Surprisingly, non-senescent CD8+T-bet+ CD57- cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.

Conclusion

Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+T-bet+ CD57- CD28lowCD27lowCD127low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+T-bet+ cells as a predominant biomarker of this disease.  相似文献   
7.
目的 研究不同IL-15基因转染对NCI-H446细胞诱导外周血单个核细胞(PBMC)增殖和杀伤肿瘤细胞的影响.方法 野生型NCI-H446细胞(Cw)和被3种IL-15基因分别转染的3种NCI-H446细胞(Cmp:被IL-15成熟肽基因转染;Cp:被原型IL-15基因转染;Csp:被信号肽换为IL-2信号肽的改型IL-15基因转染),用丝裂霉素(M)处理后(分别名为MCw、MCmp、MCp和MCsp)作为刺激细胞刺激健康志愿者的PBMC.对这些被刺激的PBMC,分别名为MCw-PBMC、MCmp-PBMC、MCp-PBMC和MC-sp-PBMC.台盼蓝拒染法计数细胞数,流式细胞术测定CD4 细胞和CD8 细胞百分率.在MCmp-PBMC,MCp-PBMC和MCsp-PBMC中,选择其细胞数和CD4 细胞和/或CD8 细胞百分率统计学上明显高于MCw-PBMC的作为效应细胞,MTT法测定它们对Cw的杀伤.结果 与MCw-PBMC相比,MCp-PBMC在细胞数、CD4 细胞和CD8 细胞百分率及对Cw的杀伤上,均显著提高(P<0.05).结论 原型IL-15基因转染能提高NCI-H446细胞诱导PBMC增殖和杀伤野生型NCI-H446细胞的能力.  相似文献   
8.
Lipopolysaccharide (LPS) binds to LPS-binding protein (LBP) in plasma and is delivered to the cell surface receptor CD14 on human monocyte. LPS is transferred to the transmembrane signaling receptor toll-like receptor (TLR) 4. In the present study, the effect of histamine on the expression of CD14 on human monocytes was investigated. Histamine concentration- and time-dependently decreased the expression of cell surface CD14, whereas histamine did not decrease mRNA for CD14 nor increase soluble CD14 (sCD14). The inhibitory effects of histamine on CD14 expression were antagonized by H2-receptor antagonist, but not by H1 and H3/H4 antagonist. The effects of selective H2-receptor agonists, 4-methylhistamine and dimaprit, on CD14 expression mimicked that of histamine indicating that histamine regulated CD14 expression through the stimulation of H2-receptors. The pretreatment with histamine partially inhibited the LPS-induced TNF-alpha production in human peripheral blood mononuclear cells (PBMC). Such inhibition might be due to the down-regulation of CD14 expression on monocytes by histamine.  相似文献   
9.
HIV infection is characterized by the loss of CD4+ T cells as well as the loss of T-cell function, leading to severe immunodeficiency. The proliferative capacity of T cells measured in vitro as responses to antigens and mitogens is severely reduced during HIV infection. An increased level of the intracellular second messenger adenosine 3',5'-cyclic monophosphate (cAMP) has been shown to cause impaired proliferative capacity of peripheral blood mononuclear cells (PBMC) from HIV-infected individuals in vitro. Sumatriptan, a 5HT1d receptor agonist, inhibits the activity of adenylyl cyclases, the enzymes responsible for regulation of the intracellular levels of cAMP. In a preliminary study sumatriptan increased the proliferative responses of PBMC to a polyclonal activator in vitro in 9 of 10 HIV-seropositive individuals (p=0.007), and in 7 of 9 healthy blood donors (p=0.05). This was probably due to a decrease in the intracellular level of cyclic AMP.  相似文献   
10.
The use of Percoll for isolation and subfractionation of PBMC and T-lymphocytes by discontinuous and continuous density gradient centrifugation is described: PBMC were isolated from human peripheral blood by discontinuous density gradient centrifugation on Percoll. The use of Percoll instead of Ficoll-Isopaque has the advantage that Percoll, in contrast to Ficoll-Isopaque, does not alter the density of monocytes. Therefore, a better separation of lymphocytes and monocytes was achieved after subsequent continuous density gradient centrifugation on Percoll. E-RFC were isolated by discontinuous density gradient centrifugation after a first low speed centrifugation step banding lymphocytes and SRBC on a Percoll-Ficoll cushion, and a subsequent high speed centrifugation step separating high density rosettes and SRBC from low density non-E-RFC. The advantage of this procedure is the short time of performance and that there is no need to resuspend the lymphocyte/SRBC pellet. PBMC, nph.PBMC T-lymphocytes were further subfractionated by continuous density gradient centrifugation on Percoll. The method described here resulted in a good separation of lymphocytes and monocytes. However, to obtain lymphocyte fractions with minute numbers of contaminating monocytes, a depletion of monocytes prior to further subfractionation of the lymphocytes by continuous density gradient centrifugation is recommended. A marker analysis of T-lymphocytes subfractionated by continuous density gradient centrifugation on Percoll shows that high density T-lymphocytes are enriched in ANAE positive lymphocytes of type 1 and depleted of ANAE positive lymphocytes of type 2. Low density T-lymphocytes are enriched in ANAE type 2 cells and depleted of ANAE type 1 cells. On the other hand, no considerable differences were found when analyzing the T-cells from different fractions for differentiation antigens by means of monoclonal antibodies (anti Lyt 3, OKT4, and OKT8). The results may indicate that subfractionation of T-lymphocytes by continuous density gradient centrifugation on Percoll provided T-cells in different functional states rather than T-cells of distinct subclasses.  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