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   81735篇
  免费   6437篇
  国内免费   2586篇
耳鼻咽喉   469篇
儿科学   1780篇
妇产科学   1158篇
基础医学   14752篇
口腔科学   1282篇
临床医学   5812篇
内科学   12050篇
皮肤病学   1870篇
神经病学   5759篇
特种医学   1134篇
外国民族医学   16篇
外科学   5819篇
综合类   9927篇
现状与发展   11篇
预防医学   5570篇
眼科学   1220篇
药学   12834篇
  14篇
中国医学   4478篇
肿瘤学   4803篇
  2023年   1126篇
  2022年   1324篇
  2021年   2494篇
  2020年   2633篇
  2019年   3067篇
  2018年   2954篇
  2017年   2784篇
  2016年   2726篇
  2015年   2977篇
  2014年   4797篇
  2013年   5817篇
  2012年   4886篇
  2011年   5862篇
  2010年   4780篇
  2009年   4165篇
  2008年   3859篇
  2007年   3566篇
  2006年   3079篇
  2005年   2587篇
  2004年   2350篇
  2003年   2152篇
  2002年   1733篇
  2001年   1466篇
  2000年   1213篇
  1999年   1130篇
  1998年   903篇
  1997年   831篇
  1996年   757篇
  1995年   768篇
  1994年   686篇
  1993年   608篇
  1992年   541篇
  1991年   462篇
  1990年   390篇
  1989年   303篇
  1988年   285篇
  1987年   215篇
  1986年   216篇
  1985年   871篇
  1984年   1105篇
  1983年   866篇
  1982年   987篇
  1981年   929篇
  1980年   694篇
  1979年   644篇
  1978年   463篇
  1977年   378篇
  1976年   428篇
  1975年   326篇
  1973年   209篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
目的:探究蛋白磷酸酶2A(CIP2A)在子宫内膜样腺癌中的表达情况及临床意义。方法:选取2011年1月至2014年3月行手术切除并经病理证实的50例子宫内膜样腺癌(EAC)及同期行门诊刮宫术获取的40例正常增生期子宫内膜(NE)组织标本。应用RT-PCR、Western blot法检测EAC和NE组织中CIP2A mRNA及蛋白水平,免疫组化法检测CIP2A阳性表达情况。分析CIP2A在EAC和NE组织中的表达差异及与子宫内膜样腺癌临床病理特征的关系。采用Kaplan-Meier法分析CIP2A不同表达水平对患者预后生存的影响,通过COX分析预后独立危险因素。结果:免疫组化染色显示:CIP2A在子宫内膜样腺癌中呈高表达,阳性着色定位于细胞浆和细胞核中,EAC组织中CIP2A阳性表达率显著高于NE组织(P<0.01)。RT-PCR和Western blot检测显示EAC组织中CIP2A mRNA及蛋白表达水平高于NE组织(P<0.01)。CIP2A表达与EAC的组织学分级、FIGO分期、宫颈管受累情况、p53表达及Ki-67增殖指数有关(P<0.05)。Kaplan-Meier法生存分析显示EAC患者5年无病生存率为92.0%、总生存率为88.0%;CIP2A表达、组织学分级、FIGO分期、肌层浸润深度、附件转移、脉管内癌栓及Ki-67增殖指数与患者预后不良相关(P<0.05)。多因素分析显示,组织学分级、FIGO分期及脉管内癌栓是影响子宫内膜样腺癌患者预后生存的独立危险因素(P<0.05)。结论:CIP2A在子宫内膜样腺癌中呈高表达,与患者总生存率下降相关,并非影响患者预后的独立危险因素。  相似文献   
53.
目的:观察艳山姜挥发油对氧化低密度脂蛋白(ox-LDL)诱导巨噬细胞转化为泡沫细胞的抑制作用,并探索其机制。方法:使用佛波酯(PMA,100μg·L^-1)诱导人白血病单核细胞(THP-1)24 h后形成巨噬细胞,实验分为4组,分别为空白组(无血清RPMI 1640),模型组(80 mg·L^-1ox-LDL),艳山姜挥发油低剂量组(80 mg·L^-1ox-LDL+4μg·L^-1艳山姜挥发油),艳山姜挥发油高剂量组(80 g·L^-1ox-LDL+20μg·L^-1艳山姜挥发油)。噻唑蓝(MTT)比色法检测艳山姜挥发油对巨噬细胞的活性的影响,蛋白免疫印迹法(Western blot)检测巨噬细胞中白细胞分化抗原36(CD36)和三磷酸腺苷结合盒转运体A1(ABCA1)的表达,酶联免疫吸附测定(ELISA)检测巨噬细胞内胆固醇酯含量,油红O染色法检测巨噬细胞中脂质小滴的含量。结果:艳山姜挥发油对巨噬细胞无毒性。与空白组比较,模型组的巨噬细胞内脂滴和胆固醇酯的含量显著增加(P<0.01),CD36蛋白表达显著上升(P<0.01),ABCA1蛋白表达无显著变化;与模型组比较,艳山姜挥发油显著抑制巨噬细胞中脂滴和胆固醇酯的含量(P<0.01),下调CD36的蛋白表达(P<0.01),上调ABCA1蛋白的表达(P<0.01),艳山姜挥发油可抑制巨噬细胞向泡沫细胞的转化。结论:艳山姜挥发油对ox-LDL诱导的巨噬细胞向泡沫细胞的形成具有抑制作用,该药理作用与艳山姜挥发油下调巨噬细胞CD36和上调ABCA1蛋白的表达有关。  相似文献   
54.
Embryonal carcinomas (ECs) and seminomas are testicular germ cell tumors. ECs display expression of SOX2, while seminomas display expression of SOX17. In somatic differentiation, SOX17 drives endodermal cell fate. However, seminomas lack expression of endoderm markers, but show features of pluripotency. Here, we use chromatin immunoprecipitation sequencing to report and compare the binding pattern of SOX17 in seminoma-like TCam-2 cells to SOX17 in somatic cells and SOX2 in EC-like 2102EP cells. In seminoma-like cells, SOX17 was detected at canonical (SOX2/OCT4), compressed (SOX17/OCT4) and noncomposite SOX motifs. SOX17 regulates TFAP2C, PRDM1 and PRDM14, thereby maintaining latent pluripotency and suppressing somatic differentiation. In contrast, in somatic cells canonical motifs are rarely bound by SOX17. In sum, only 12% of SOX17-binding sites overlap in seminoma-like and somatic cells. This illustrates that binding site choice is highly dynamic and cell type specific. Deletion of SOX17 in seminoma-like cells resulted in loss of pluripotency, marked by a reduction of OCT4 protein level and loss of alkaline phosphatase activity. Furthermore, we found that in EC-like cells SOX2 regulates pluripotency-associated genes, most likely by partnering with OCT4. In conclusion, SOX17 (in seminomas) functionally replaces SOX2 (in ECs) to maintain expression of the pluripotency cluster.  相似文献   
55.
目的:探究滋阴清嗓汤对咳嗽变异性哮喘(CVA)发作期患儿免疫球蛋白E(IgE)、白细胞介素-4(IL-4)、白细胞介素-5(IL-5)的影响及安全性。方法:选取2018年1月—2019年6月在河南省儿童医院东三街院区呼吸科一病区住院治疗的170例CVA患儿,随机分为中医联合组(85例)和西医常规组(85例)。所有患儿均给予西医常规治疗,中医联合组加用滋阴清嗓汤。两组均连续治疗14 d后,观察并比较两组的疗效、症状改善时间、临床主要症状积分、外周血单个核细胞(PBMC)内IL-4、IL-5、血清IgE水平、呼出气一氧化氮(FeNO)及肺功能指标水平。结果:中医联合组患儿痊愈率为80.00%(68/85),显著高于西医常规组痊愈率61.18%(52/85)(P<0.05)。中医联合组患儿症状改善时间(咳嗽减轻、咳嗽消退、夜咳停止的时间)均显著短于西医常规组(P<0.05)。治疗后,两组患儿咳嗽、咽痛、喉痒评分均显著下降,且中医联合组显著低于西医常规组(P<0.05)。治疗后,两组患儿PBMC内IL-4、IL-5及血清IgE水平均显著下降,且中医联合组均显著低于西医常规组(P<0.05)。治疗后,两组患者FeNO和1 s用力呼气容积(FEV1)均显著下降(P<0.05),呼气峰流速(PEF)均显著升高(P<0.05),组间比较,中医联合组均显著优于西医常规组(P<0.05)。两组患者在治疗期间均未发生明显不良反应和不良事件。结论:滋阴清嗓汤对CVA发作期患儿具有良好的疗效,可发挥较好的滋阴清热、止咳平喘、改善慢性炎症作用,有效改善其临床症状,安全性高,值得推广。  相似文献   
56.
57.
Skin injury can trigger formation of new lesions in psoriasis (Koebner phenomenon). The mechanisms through which injury exacerbates psoriasis are unclear. During wound repair, epidermal keratinocytes are activated and produce abundant IL‐36γ, further promoting the skin inflammation. IL‐17A is the cornerstone cytokine in the pathogenesis of psoriasis. We sought to investigate the effects of IL‐17A on injury‐induced keratinocyte activation and IL‐36γ production. Here, we demonstrated that dsRNA released from necrotic keratinocytes induced the expression of IL‐36γ. Silencing of TLR3 by siRNA decreased the IL‐36γ induction by necrotic keratinocyte supernatant. Co‐stimulation with dsRNA and IL‐17A synergistically increased the expression of IL‐36γ and other proinflammatory mediators (CCL20, CXCL8, DEFB4 and LCN2) in keratinocytes. The synergistic effects were not dependent on TLR3 upregulation, TNF receptor signalling and mRNA stabilization. Co‐stimulation with dsRNA and IL‐17A resulted in an accumulation of IκBζ. The synergistic upregulation of IL‐36γ and proinflammatory mediators were inhibited by IκBζ siRNA. Co‐stimulation with IL‐17A and poly(I:C) markedly activated the p38 MAPK and NF‐κB pathway, compared with poly(I:C). Blockade of p38 MAPK and NF‐κB suppressed dsRNA/IL‐17A–mediated IκBζ and IL‐36γ induction. These findings demonstrated that IL‐17A synergistically enhanced the dsRNA‐mediated IL‐36γ production through a p38 MAPK‐, NF‐κB–, and IκBζ‐dependent mechanism.  相似文献   
58.
Background and study aimsNon-invasive biomarkers of inflammatory bowel diseases (IBD) are of critical importance. Here, we evaluated the S100A8 and S100A9 mRNA expression, as the heterodimers of calprotectin, in the blood leucocytes of IBD patients to find how their expression associates with the disease characteristics.Patients and methodsIn this cross-sectional study, 59 IBD patients and 30 healthy subjects were included. The flare and remission phases of disease were identified in 46 and 13 patients, respectively. Blood leucocytes were isolated, and the S100A8 and S100A9 mRNA expression were evaluated in the isolated leucocytes using relative quantification real-time PCR.ResultsThe mean S100A8 and S100A9 mRNA expression were significantly higher in IBD patients than in the controls (p = 0.03 and p = 0.02, respectively). The mean S100A8 and S100A9 mRNA expression were significantly higher in the flare phase of the disease compared with the remission phase (p = 0.01 and p = 0.007, respectively). S100A8 distinguished IBD patients from controls with the sensitivity and specificity of 73% and 64%, and flare phase of disease from remission with the sensitivity and specificity of 67% and 62%. On the other hand, S100A9 distinguished IBD patients from controls with the sensitivity and specificity of 81% and 70%, and flare phase of disease from remission with the sensitivity and specificity of 68% and 64%.ConclusionThe S100A8 and S100A9 mRNA are differentially expressed in blood leucocytes of IBD patients compared to healthy controls as well as active versus quiescent disease. Thus, they can be potentially used as a blood-based biomarker in the monitoring of IBD.  相似文献   
59.
60.
Background: Endplate inflammation remains a difficult disease to treat, in part due to its unclear pathology. Previous experiments showed that patients with idiopathic inflammation presented a systemic upregulation of Th17 cells. Here, we investigated how this change might affect the inflammatory environment in endplate inflammation.

Methods: Peripheral blood was obtained from patients and healthy controls, and Th17 cells were examined.Results: Th17 cells significantly increased the differentiation of CD11c+ and DC-SIGN+ dendritic cells (DCs) from circulating monocytes in the absence of exogenous stimulation as well as in the presence of LPS stimulation. Th17 cells also increased CD80 and CD86 expression by DCs. Importantly, although Th17 cells from both healthy controls and patients with endplate inflammation could induce CD11c, DC-SIGN, CD80, and CD86 expression, Th17 cells from patients with endplate inflammation showed significantly more potent capacity. Both contact-dependent and IL-17-dependent mechanisms were employed by Th17 cells, since blocking cell-to-cell contact significantly inhibited Th17-mediated differentiation of CD11c+ DCs, and neutralization of IL-17 reduced the expression of CD80 and CD86. Strikingly, DCs following incubation with Th17 cells, but not the DCs derived directly from monocytes without Th17 cells, could significantly promote the expression of IL-17 from naive CD4+ T cells.

Conclusions: These results demonstrated that Th17 cells from patients with endplate inflammation could potently induce the differentiation and activation of DCs that preferentially promoted IL-17 response in a positive feedback loop.  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