全文获取类型
收费全文 | 39795篇 |
免费 | 2758篇 |
国内免费 | 1650篇 |
专业分类
耳鼻咽喉 | 373篇 |
儿科学 | 581篇 |
妇产科学 | 595篇 |
基础医学 | 5200篇 |
口腔科学 | 903篇 |
临床医学 | 3493篇 |
内科学 | 5945篇 |
皮肤病学 | 697篇 |
神经病学 | 1553篇 |
特种医学 | 1564篇 |
外国民族医学 | 4篇 |
外科学 | 4522篇 |
综合类 | 6336篇 |
现状与发展 | 5篇 |
预防医学 | 1446篇 |
眼科学 | 422篇 |
药学 | 4014篇 |
10篇 | |
中国医学 | 1443篇 |
肿瘤学 | 5097篇 |
出版年
2024年 | 73篇 |
2023年 | 478篇 |
2022年 | 1078篇 |
2021年 | 1286篇 |
2020年 | 1266篇 |
2019年 | 974篇 |
2018年 | 968篇 |
2017年 | 1119篇 |
2016年 | 1155篇 |
2015年 | 1228篇 |
2014年 | 2489篇 |
2013年 | 2686篇 |
2012年 | 2488篇 |
2011年 | 2690篇 |
2010年 | 2240篇 |
2009年 | 2219篇 |
2008年 | 2253篇 |
2007年 | 2187篇 |
2006年 | 1942篇 |
2005年 | 1769篇 |
2004年 | 1524篇 |
2003年 | 1399篇 |
2002年 | 1097篇 |
2001年 | 1111篇 |
2000年 | 913篇 |
1999年 | 832篇 |
1998年 | 717篇 |
1997年 | 642篇 |
1996年 | 554篇 |
1995年 | 487篇 |
1994年 | 421篇 |
1993年 | 276篇 |
1992年 | 216篇 |
1991年 | 195篇 |
1990年 | 188篇 |
1989年 | 126篇 |
1988年 | 126篇 |
1987年 | 88篇 |
1986年 | 80篇 |
1985年 | 100篇 |
1984年 | 106篇 |
1983年 | 49篇 |
1982年 | 65篇 |
1981年 | 56篇 |
1980年 | 60篇 |
1979年 | 61篇 |
1978年 | 34篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Hyperthermic modulation of macrophage-tumor cell interactions 总被引:3,自引:0,他引:3
Hyperthermia in the febrile (41° C) or tumor therapeutic (42° C) ranges is known to alter tumor-host interactions: there are reports of either inhibitory or enhancing effects on tumor metastasis and various host defense mechanisms. Historically, this has been an area of conflicting and often anecdotal reports, and there are still significant gaps in our knowledge of the effects of temperature on tumor-host interactions. However, we believe that the tools are now available to further our understanding of the complex relationships between febrile episodes or therapeutically applied heat and various tumor-host cytotoxic mechanisms, and that potentially important and exploitable relationships can be defined. In this review we give an overview of the current status of this field and the factors that have shaped it. We also describe our recent experimental work with macrophages and their monokines, primarily tumor necrosis factor (TNF), which we feel offers new scientific and clinical opportunities for future studies. 相似文献
102.
目的 探讨中国江苏地区汉族人群肿瘤坏死因子 β遗传多态性分布。方法 收集江苏地区 16 8名无血缘关系健康个体的静脉血提取DNA ,应用聚合酶链反应限制性片段长度多态性 (PCR -RFLP) ,对TNFβ基因多态性进行分析。结果 TNFβ检测到三个等位基因 ,其基因型频率分别为TNFβ 1/ 1=2 1 4 % ,TNFβ 1/ 2 =4 7% ,TNFβ 2 / 2 =31 5 % ,基因型分布符合Hardy-Weinberg定律。统计分析显示 :江苏地区汉族人群TNFβ等位基因频率分布与欧美白种人均有显著性差异(P <0 0 5 )。结论 TNFβ等位基因频率分布具有种族差异 相似文献
103.
Sen Pathak 《Cancer Genetics and Cytogenetics》1980,1(3):281-289
Cytogenetic analysis using C-, G-, and Ag-nucleolus organizer region (NOR) staining techniques, performed on established cell lines as well as directly processed breast tumor effusions, revealed that: 1) chromosome No. 1 is involved in translocation; 2) based on 1q translocation chromosome, breast tumors could be classified into two groups; and 3) double minutes and homogeneously staining regions may be present in breast tumor cells in vivo as well as in vitro, and that homogeneously staining regions may exhibit some heterogeneity in staining. 相似文献
104.
Insulin-dependent diabetes mellitus (IDDM) and Graves' disease (GD) are autoimmune endocrinopathies and associated with distinct HLA-DR and -DQ alleles as well as several tumor necrosis factor a (TNF-α) and β (TNF-β) alleles. TNF-α and TNF-β interact with TNF receptor (TNF-R), of which two subtypes have been described: TNF-R1 and TNF-R2. We investigated TNF-R2 alleles in 90 patients with IDDM, 101 with GD and 70 healthy controls. Genomic DNA was amplified with specific flanking primers for the untranslated 3 region of TNF-R2. SSCP analysis revealed two alleles by different fragment patterns: TNF-R2*1 and TNF-R2*2. Patients with IDDM or Graves' disease and controls did not differ significantly: TNF-R2*1/*1:IDDM(8%)/GD(2%)/KO(4%); TNF-R2*2/*2:IDDM(34%)/GD(48%)/KO(42%), heterozygosity TNF-R2*1/*2:IDDM(58%)/GD(50%)/KO(54%) (IDDM vs KO: P =0.46, χ2 =1.57; GD vs KO: P =0.59, χ2 =1.05). In conclusion, the studied polymorphism of TNF-R2 was associated with neither IDDM nor GD in a German population. 相似文献
105.
Evaluation of stromal metalloproteinases and vascular endothelial growth factors in a spontaneous metastasis model 总被引:5,自引:0,他引:5
Donadio AC Durand S Remedi MM Frede S Ceschin DG Genti-Raimondi S Chiabrando GA 《Experimental and molecular pathology》2005,79(3):259-264
This study aims to investigate MMP2 and MT1-MMP protein as well as VEGF-C and VEGF-D mRNA expression in tumor cells and distant organs considered to be targets for metastasis in a tumor spontaneous metastasis model previously described. Cultured tumor cells, able to express pro-MMP2, MMP2, pro-MMP9, and MT1-MMP, develop tumor growth and metastasis, mainly in the liver and spleen, when they are injected in the mammary pad gland of Wistar rats. Immunohistochemical studies of tumor masses showed small groups of tumor cells staining for MT1-MMP but not for MMP2. In the liver, tumor metastatic foci and a stromal positive staining for both MMP2 and MT1-MMP were shown. The spleen and lymph nodes, with only scattered metastatic cells, did not show MMPs immunostaining. Using RT-PCR, a significantly higher VEGF-C and VEGF-D gene expression was shown in the liver of tumor-bearing rats respect to normal rats, whereas spleen and lymph nodes did not show significant differences in mRNA VEGF-C/D levels. Taken together, our results suggest that the stroma microenvironment of target organs for metastasis has the ability to produce MMPs and VEGFs that facilitate the anchorage of tumor cells and promote tumor cell growth and angiogenesis. 相似文献
106.
Osteopontin affects the persistence of beta-glucan-induced hepatic granuloma formation and tissue injury through two distinct mechanisms 总被引:4,自引:0,他引:4
Morimoto J Inobe M Kimura C Kon S Diao H Aoki M Miyazaki T Denhardt DT Rittling S Uede T 《International immunology》2004,16(3):477-488
Osteopontin (OPN) plays a pivotal role in various immune responses and inflammatory diseases. OPN is expressed in various granulomatous diseases; however, the cellular and molecular role of OPN in these diseases is not well known. We analyzed the role of OPN in a beta-glucan-induced hepatic granuloma model. First, we found that neither OPN deficiency nor overexpression of OPN affected the number and the size of hepatic granulomas at day 7, indicating that OPN is not involved in the formation of hepatic granulomas at the early stages. Importantly, OPN did not influence the liver tissue damage as defined by alanine aminotransferase and aspartate aminotransferase levels at early stages. Second, OPN deficiency resulted in the reduction of IL-12 and IFN-gamma production at early stages. Third, at late stages, OPN deficiency resulted in a decrease in the number and size of hepatic granulomas, and a reduction of liver tissue injury. This was due to the reduction of the cellular recruitment including macrophages, CD4 T cells and dendritic cells into the liver, and the reduction of tumor necrosis factor (TNF)-alpha production in the liver. In contrast, overexpression of OPN resulted in the persistence of granuloma formation. These data suggest that OPN affects the persistence of hepatic granuloma formation. Our results indicate that OPN up-regulates the production of IL-12 and IFN-gamma within the granulomas at early stages, and OPN has an additional role in the regulation of cellular recruitment and TNF-alpha production at late stages that determine the severity of liver tissue injury. 相似文献
107.
目的对子宫颈鳞癌(Cervical squamous cell carcinoma,CSCC)组织中T、B、NK淋巴细胞的浸润与肿瘤免疫状况进行研究,探讨免疫细胞的变化规律,阐明局部免疫状态对CSCC发展的影响,为CSCC的免疫治疗及预后提供理论依据和参考指标.方法用免疫组织化学(S-P)法,以CD4、CD8标记T细胞、CD20标记B细胞、CD57标记NK细胞,经计数分析和SPSS11.0统计软件处理.结果在早期CSCC组织中浸润淋巴细胞种类与数量依次为CD8+、CD20+、CD57+和CD4+,差别显著(P<0.05).在进展期CSCC组织中浸润淋巴细胞类型与数量依次为CD8+、CD20+、CD4+和CD57+,差别显著(P<0.05).4种淋巴细胞在进展期高分化CSCC中的数量,无显著差异(P>0.05);但在进展期中、低分化CSCC中的数量,均存在着显著差异(P<0.05).T淋巴细胞浸润的数量伴随分化程度的降低而增高,尤其CD8+T淋巴细胞增加更明显;CD4+/CD8+T淋巴细胞<1,且CD4+与CD8+T淋巴细胞的比例逐渐降低.结论在CSCC组织中浸润的淋巴细胞中以T细胞为主,其次为B细胞,NK细胞浸润最少,说明CSCC局部以细胞免疫为主,体液免疫也不容忽视.CD8+T细胞比例增加是细胞免疫受抑制的表现.CSCC组织中T细胞抗肿瘤免疫受到抑制,需要免疫调节,增强抗肿瘤免疫力. 相似文献
108.
Dr. Yvonne Paterson 《Immunologic research》1998,17(1-2):191-207
Our studies are mainly focused on developing strategies of immune regulation. In the case of infectious and neoplastic disease,
our approach is to upregulate cell-mediated immunity to viral of tumor antigens using an intracellular bacterium as a vector
for targeting these antigens to the major histocompatibility complex (MHC) class I and class II pathways of antigen processing,
in addition to exploiting the adjuvant properties of the vector to stimulate innate immunity. In the area of autoimmunity,
we are attempting to downregulate the immune response by specific immune intervention directed against autoreactive T cells.
In these studies we use murine models for multiple sclerosis. Our approach is to use both rationally designed T cell receptor
(TCR) peptide analogs and recombinant viral vectors that express TCR components to regulate the disease. 相似文献
109.
Federica Cavallo Alfonso Martin-Fontecha Matteo Bellone Silvia Heltai Evelina Gatti Paola Tornaghi Massimo Freschi Guido Forni Paolo Dellabona Giulia Casorati 《European journal of immunology》1995,25(5):1154-1162
Although the transfection of B7-1 cDNA into a few mouse tumor cell lines can induce anti-tumor T cell immunity, its expression alone is ineffective in many other tumor cell lines tested. We were interested to study what factors limit B7-1 co-stimulatory activity, and decided to investigate whether B7-1 requires the cooperation of ICAM-1 to provide the minimal co-stimulatory signal for establishing an efficient anti-tumor immunity. We show that the transfection of B7-1 cDNA into three ICAM-1+ (plasmocytoma J558L, T lymphomas EL-4 and RMA), but not into two ICAM-1? tumor cell lines (adenocarcinoma TS/A and melanoma B16.F1), is sufficient to induce their complete rejection in syngeneic mice. The expression of ICAM-1 is necessary for the rejection of the B7 expressing tumors, since the primary response elicited by B7-1+ EL-4 and RMA clones expressing reduced levels of ICAM-1 is severely reduced. Furthermore, super-transfection of ICAM-1 cDNA into B7-1+ adenocarcinoma and melanoma clones optimizes their primary rejection. Histologic examination of transfected tumors reveals that B7-1 and ICAM-1 exert a potent pro-inflammatory activity. The intra-tumor infiltration is composed of both eosinophils and lymphomono-cytes, and is already massive 5 days after the tumor challenge. The primary rejection of the B7-1+ ICAM-1+ tumors depends critically on CD8+ T cells, natural killer cells and granulocytes, but is independent of CD4+ T cells. Remarkably, in addition to its effects on the early phases of the immune response, the co-expression of ICAM-1 and B7-1 on tumors is also necessary for the efficient induction of a memory response. In fact, only the primary challenge with B7-1+, ICAM-1+ tumor cells protects the majority of the mice from a second injection of parental tumor cells. Collectively, our findings indicate that B7-1 and ICAM-1 are fundamental components for triggering the primary rejection of tumors and establishing a protective memory response. These findings may help to define new strategies for the rational application of co-stimulation in tumor immunotherapy. 相似文献
110.
Timo L. M. ten Hagen Ann L. B. Seynhaeve Alexander M. M. Eggermont 《Immunological reviews》2008,222(1):299-315
Summary: Solid tumor therapy with chemotherapeutics greatly depends on the efficiency with which drugs are delivered to tumor cells. The typical characteristics of the tumor physiology promote but also appose accumulation of blood-borne agents. The leaky tumor vasculature allows easy passage of drugs. However, the disorganized vasculature causes heterogeneous blood flow, and together with the often-elevated interstitial fluid pressure, this state results in poor intratumoral drug levels and failure of treatment. Manipulation of the tumor vasculature could overcome these barriers and promote drug delivery. Targeting the vasculature has several advantages. The endothelial lining is readily accessible and the first to be encountered after systemic injection. Second, endothelial cells tend to be more stable than tumor cells and thus less likely to develop resistance to therapy. Third, targeting the tumor vasculature can have dual effects: (i) manipulation of the vasculature can enhance concomitant chemotherapy, and (ii) subsequent destruction of the vasculature can help to kill the tumor. In particular, tumor necrosis factor α is studied. Its action on solid tumors, both directly through tumor cell killing and destruction of the tumor vasculature and indirectly through manipulation of the tumor physiology, is complex. Understanding the mechanism of TNF and agents with comparable action on solid tumors is an important focus to further develop combination immunotherapy strategies. 相似文献