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   662篇
  免费   18篇
  国内免费   16篇
耳鼻咽喉   4篇
儿科学   1篇
妇产科学   5篇
基础医学   218篇
口腔科学   5篇
临床医学   29篇
内科学   99篇
皮肤病学   13篇
神经病学   25篇
特种医学   10篇
外科学   52篇
综合类   53篇
预防医学   46篇
眼科学   1篇
药学   38篇
中国医学   9篇
肿瘤学   88篇
  2023年   4篇
  2022年   5篇
  2021年   7篇
  2020年   9篇
  2019年   11篇
  2018年   13篇
  2017年   10篇
  2016年   5篇
  2015年   14篇
  2014年   42篇
  2013年   33篇
  2012年   21篇
  2011年   29篇
  2010年   19篇
  2009年   31篇
  2008年   44篇
  2007年   35篇
  2006年   39篇
  2005年   34篇
  2004年   34篇
  2003年   26篇
  2002年   16篇
  2001年   17篇
  2000年   14篇
  1999年   11篇
  1998年   8篇
  1997年   14篇
  1996年   13篇
  1995年   17篇
  1994年   15篇
  1993年   19篇
  1992年   11篇
  1991年   9篇
  1990年   10篇
  1989年   10篇
  1988年   5篇
  1987年   4篇
  1986年   3篇
  1985年   6篇
  1984年   3篇
  1983年   5篇
  1982年   2篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1978年   3篇
  1977年   1篇
  1976年   2篇
  1972年   1篇
排序方式: 共有696条查询结果,搜索用时 15 毫秒
1.
《Vaccine》2019,37(22):2952-2959
CD8+ T cells are known to control infections, but their role in preventing latent infection from establishing has not been thoroughly investigated.We hypothesized that a potent CD8+ T cell response patrolling the mucosal viral entry points could kill the first infected cells and thereby abrogate the infection before latency is established.To investigate this, replication deficient adenovirus serotype 5 vectors encoding murine γ-herpesvirus-68 CD8+ T cell epitopes linked to the T cell adjuvant Invariant chain, were developed. We show that intranasal vaccination of mice reduces the risk of establishment of latent infection from multiple intranasal ID50 challenges with murine γ-herpesvirus-68 by 81% per exposure at 14 days post vaccination. Protection waned over time, but immune responses were extended by heterologous prime-boost vaccination applied simultaneously intramuscularly and intranasally, and animals vaccinated 66 days prior to challenge showed a strong trend of long-term protection.Our data provides evidence that CD8+ T cells are able to protect against establishment of latent infection. Although the protective efficacy is difficult to maintain over time, this proof-of-concept study suggests a role for a CD8+ T cell arm in future vaccine strategies against latent human viral infections caused by pathogens such as HIV and multiple herpes virus.  相似文献   
2.
目的探讨miR-513a-3p靶向鼠双微体基因2(MDM2)对胃癌细胞的增殖、迁移和侵袭的影响及其作用机制。方法采用脂质体法将miR-NC、miR-513a-3p、anti-miR-NC、anti-miR-513a-3p、si-NC、si-MDM2、miR-513a-3p+pcDNA3.1和miR-513a-3p+pcDNA3.1-MDM2转染至BGC-823细胞中,采用实时荧光定量聚合酶链反应(qRT-PCR)检测miR-513a-3p的表达水平,采用Western blot检测cyclin D1、MMP-2、p21、E-cadherin和MDM2蛋白的表达水平,四甲基偶氮唑蓝法检测各组胃癌细胞BGC-823的活性,Transwell法检测各组胃癌细胞BGC-823的迁移和侵袭能力,双荧光素酶报告基因检测实验检测miR-513a-3p与MDM2的靶向关系。结果胃癌细胞BGC-823、MGC-803中miR-513a-3p的表达水平分别为0.21±0.02和0.34±0.03,与胃上皮细胞GES-1(0.76±0.08)比较,差异均有统计学意义(均P<0.05)。培养24、48和72 h后,miR-NC组细胞的吸光度(A)值分别为0.57±0.05、1.03±0.10和1.43±0.14,miR-513a-3p组细胞的A值分别为0.36±0.03、0.48±0.05和0.63±0.06,差异均有统计学意义(均P<0.05);miR-NC组细胞的迁移和侵袭数分别为(130±11.80)个和(117±10.60)个,miR-513a-3p组细胞分别为(58±5.64)个和(50±5.13)个,差异均有统计学意义(均P<0.05)。培养24、48和72 h后,si-NC组细胞的A值分别为0.53±0.05、0.95±0.10和1.36±0.14,si-MDM2组细胞的A值分别为0.39±0.04、0.57±0.06和0.80±0.08;si-NC组细胞的迁移和侵袭数分别为(141±12.02)个和(109±10.60)个,si-MDM2组的迁移和侵袭数分别为(66±6.67)个和(61±6.18)个,差异均有统计学意义(均P<0.05)。培养24、48和72 h后,miR-513a-3p+pcDNA3.1组细胞的A值分别为0.34±0.03、0.46±0.05和0.61±0.06,miR-513a-3p+pcDNA3.1-MDM2组细胞的A值分别为0.48±0.05、0.82±0.08和1.17±0.12,差异均有统计学意义(均P<0.05);miR-513a-3p+pcDNA3.1组细胞的迁移和侵袭数分别为(56±5.71)个和(51±5.16)个,miR-513a-3p+pcDNA3.1-MDM2组分别为(113±10.28)个和(104±10.02)个,差异均有统计学意义(均P<0.05)。结论miR-513a-3p可抑制胃癌细胞的增殖、迁移和侵袭能力,其机制可能与靶向调控MDM2的表达有关,可为胃癌的预防和治疗提供新靶点。  相似文献   
3.
目的 探讨饮用不同浓度的葡聚糖硫酸钠(dextran sulfate sodium, DSS)对于建立小鼠炎症性肠病(inflammatory bowel disease, IBD)模型及其致病相关免疫因子表达的影响。方法 雄性C57BL/6J小鼠随机分为对照组和不同浓度的DSS饮用组(3%、5%、7%)。观察小鼠的大便性状,体重和生存时间。饮用后的第6天处死各组小鼠,观察结肠大体形态并评分;取病变处进行石蜡包埋病理切片,苏木素伊红染色并进行病理组织学评分;定量PCR检测各组脾细胞免疫因子表达情况。结果 饮用3%、5%、7%浓度DSS的小鼠在第6天均有不同程度溃疡形成,成模率随着DSS浓度提升而增加,但是小鼠死亡率也相应增加。定量PCR结果表明促炎因子(TNF-α、IFN-γ和IL-17A)的表达水平与DSS浓度成正相关,而抑炎因子(IL-4和IL-10)以及调节性T细胞相关的转录因子Foxp3的表达水平与DSS浓度成负相关关系。结论 给予小鼠5%浓度的DSS溶液饮用有助于高效经济地建立小鼠IBD模型,为进一步研究IBD的发病机理、生物学特性、干预因素等打下了重要基础。  相似文献   
4.
Although reagents are available to block mouse complement receptor type 2 and/or type 1 (CR2/CR1, CD21/CD35) function in acute or short term models of human disease, a mouse anti-rat antibody response limits their use in chronic models. We have addressed this problem by generating in Cr2/− mice a mouse monoclonal antibody (mAb 4B2) to mouse CR2/CR1. The binding of murine mAb 4B2 to CR2/CR1 directly blocked C3dg (C3d) ligand binding. In vivo injection of mAb 4B2 induced substantial down regulation of CR2 and CR1 from the B cell surface, an effect that lasted six weeks after a single injection of 2 mg of mAb. The 4B2 mAb was studied in vivo for the capability to affect immunological responses to model antigens. Pre-injection of mAb 4B2 before immunization of C57BL/6 mice reduced the IgG1 antibody response to the T-dependent antigen sheep red blood cells (SRBC) to a level comparable to that found in Cr2−/− mice. We also used the collagen-induced arthritis (CIA) model, a CR2/CR1-dependent autoimmune disease model, and found that mice pre-injected with mAb 4B2 demonstrated substantially reduced levels of pathogenic IgG2a antibodies to both the bovine type II collagen (CII) used to induce arthritis and to endogenous mouse CII. Consistent with this result, mice pre-injected with mAb 4B2 demonstrated only very mild arthritis. This reduction in disease, together with published data in CII-immunized Cr2−/− mice, confirm both that the arthritis development depends on CR2/CR1 receptors and that mAb 4B2 can be used to induce biologically relevant receptor blockade. Thus mAb 4B2 is an excellent candidate for use in chronic murine models to determine how receptor blockage at different points modifies disease activity and autoantibody responses.  相似文献   
5.
IntroductionAdult-onset Still's disease (AOSD) is a rare multisystemic disorder and a diagnostic challenge for physicians because of the wide range of differential diagnoses. Common features of AOSD and secondary hemophagocytic lymphohistiocytosis (sHLH) could favour diagnostic uncertainty, in particular in case of infection-related sHLH.ObservationA 61-year-old man was admitted to our internal medicine department for suspected AOSD. He reported a 2-week history of sudden onset fever, headaches, myalgia, sore throat, diarrhoea, and an erythematous macular rash of the trunk as well as petechial purpuric lesions on both legs on return from Reunion Island. Laboratory tests found cytopenia, hepatic cytolysis, hypertriglyceridaemia, and hyperferritinaemia. Hemophagocytosis was diagnosed on bone marrow aspiration in favour of the diagnosis of secondary hemophagocytic lymphohistiocytosis (sHLH). Subcutaneous anakinra (100 mg) was initiated to treat sHLH with favourable course. Oral doxycycline was added 3 days later because of atypical features for AOSD diagnosis such as diarrhoea, hypergammaglobulinaemia, and doubtful serologies for Rickettsia and Coxiella. Three weeks later, Rickettsia typhi serology was checked again and revealed an increase in IgG titer > 4 times that confirmed the diagnosis of murine typhus. A diagnosis of murine typhus complicated by sHLH was retained, successfully treated by anakinra and doxycycline.ConclusionOur observation shows that AOSD diagnosis has to be stringent due to the many differential diagnoses, particularly infection complicated by sHLH, which may be rare. It is important to consider murine typhus in patients returning from endemic areas, such as La Reunion or other tropical areas, when they present fever of unknown origin with non-specific clinical features. Moreover, this case illustrates the effectiveness of IL-1 blockers as a treatment for symptomatic sHLH without severity criteria, regardless of the aetiology.  相似文献   
6.
目的研究小鼠巨细胞病毒(murine cytomegalovirus,MCMV)感染C57BL/6小鼠诱导自然杀伤(natural killer,NK)细胞免疫应答的最佳剂量和最佳时间。方法分别根据剂量和时间效应进行分组,剂量效应:无特定病原体(specific pathogen free,SPF)级8周龄C57BL/6雌鼠15只,根据MCMV滴度分为四组,未感染的0个蚀斑形成单位(plaque forming unit,PFU)组(3只)、2.5×104PFU组(4只)、5.0×104PFU组(4只)和10.0×104PFU组(4只),随后常规饲养7天;时间效应:将8周龄C57BL/6雌鼠14只随机分为四组,分别为0天组(4只)、3天组(4只)、7天组(4只)、14天组(2只),建模0天腹腔注射5.0×104PFU的MCMV感染各组小鼠。在感染后对应天数处死各组小鼠,取小鼠脾脏制成单细胞悬液,并用流式细胞术分析各种组NK细胞比例、Ly49H及颗粒酶B(granzyme B,GZMB)、NK细胞溶酶体相关膜蛋白-1(CD107a)和γ-干扰素(interferon-γ,IFN-γ)的表达。结果 MCMV感染7天后,与0PFU组相比,2.5×104PFU组、5.0×104PFU组和10.0×104PFU组脾脏NK细胞占淋巴细胞的比例明显下降{(1.90±0.32)%比[(0.91±0.14)%,(0.62±0.16)%,(0.85±0.26)%],F=21.271,P<0.05},CD27+CD11b+NK细胞比例显著下降{(22.40±4.55)%比[(13.20±1.29)%,(10.78±1.21)%,(11.38±1.76)%],F=17.272,P<0.05},CD11b+NK细胞比例显著增加{(59.87±5.33)%比[(71.08±1.82)%,(74.25±1.95)%,(70.90±2.49)%],F=14.641,P<0.05)},CD43+KLRG1+NK细胞占NK细胞的比例增加{(39.40±5.73)%比[(77.00±0.67)%,( 81.23±2.21)%,( 76.63±7.36)%],F=55.282,P<0.05)},Ly49H+NK细胞亚群数量显著增加{(42.07±1.21)%比[(63.50±1.30)%,(63.58±3.71)%,(61.68±4.84)%],F=32.273,P<0.05)},组间差异具有统计学意义。在NK细胞功能方面,MCMV感染7天后,与0 PFU组相比,2.5×104PFU组、5.0×104PFU组和10.0×104PFU GZMB的表达显著增加{(287.00±30.79)%比[(384.25±63.91)%,(529.75±66.08)%,(466.50±83.38)%],F=8.730,P<0.05},IFN-γ分泌减少{(36.00±5.33)%比[(4.88±3.35)%,(3.03±1.56)%,(3.61±2.18)%],F=87.663,P<0.05}。时间效应的比较结果显示,MCMV感染3天后,NK细胞CD107a和颗粒酶B表达与0天相比显著升高[(22.98±4.58)%比(6.32±0.75)%,(5969.25±1159.86)%比(788.50±88.17)%,F值分别为41.072和67.448,P值均<0.05],差异具有统计学意义。结论本研究表明,MCMV感染C57BL/6小鼠模型可选择的最佳感染剂量为5×104PFU,最佳建模时间为感染后3天。  相似文献   
7.
目的 探讨健脾化痰方对裸鼠前胃癌(murine foregastric carcinoma,MFC)肝转移的影响及其作用机制.方法 将MFC细胞接种于裸鼠脾脏,建立裸鼠肝转移模型后用随机数字表法分为模型组、5-fu注射液组及健脾化痰方高、中、低剂量组,健脾化痰方高、中、低剂量组分别灌胃80、40、20g/kg的健脾化痰方煎剂,5-fu组腹腔注射60mg/kg 5-fu注射液,模型组灌胃等体积生理盐水,1次/d,共4周.实验结束时计算裸鼠体重、脾脏瘤重,评估肝脏转移情况,用RT-PCR法、免疫组织化学法分别检测P53、Bcl-2基因和相应蛋白表达的情况.结果 与模型组比较,健脾化痰方中剂量组、高剂量组裸鼠体重[(21.40±1.43)g、(21.70±1.02)g比(20.37±1.17)g]明显增加(P<0.05),脾脏瘤重[(0.26±0.13)g、(0.16±0.05)g比(0.63±0.17)g]明显减轻(P<0.05);健脾化痰方中、高剂量组裸鼠肝脏表面转移瘤数目较少(P<0.05);与模型组比较,健脾化痰方低、中、高剂量组P53 mRNA表达[(8.32±0.38)、(5.42±0.45)、(3.09±0.26)比(9.67±1.31)]、Bcl-2 mRNA表达[(4.65±0.61)、(3.22±0.21)、(2.49±0.19)比(5.32±0.42)]均降低(P<0.05);健脾化痰方低、中、高剂量组脾脏接种瘤组织中P53蛋白的阳性表达率[(76.11±5.23)、(45.20±3.77)、(23.11±3.14)比(81.63±5.01)]均低于模型组(P<0.05),Bcl-2蛋白[分别为(58.67±5.27)、(32.00±3.13)(19.00±2.54)比(63.00±4.10)]均低于模型组(P<0.05).结论 健脾化痰方可抑制裸鼠前胃癌移植瘤的生长及肝转移,下调P53、Bcl-2基因和相应蛋白的表达.  相似文献   
8.
9.
This study isolated polysaccharides from strawberry (SP) and mulberry (MP) fruit juice to compare their cytokine secretion regulatory and antiapoptotic activities using murine primary splenocytes. SP and MP in the absence or presence of lipopolysaccharide (LPS) were administered to splenocytes for 48 hours. The culture supernatant was used for cytokine secretion assay using the enzyme-linked immunosorbent assay method. The cell pellet was used for the determination of anti-/proapoptotic protein (B cell lymphoma 2/Bak) levels in the cells using the Western blotting method. The results showed that SP and MP treatment at appropriate concentrations significantly increased the proliferation of splenocytes (p < 0.05). SP and MP treatments in the absence of LPS, and SP treatments in the presence of LPS significantly decreased T helper type 1/T helper type 2 (p < 0.05), and SP in the presence of LPS slightly decreased tumor necrosis factor-α/interleukin-10 (pro-/anti-inflammatory) cytokine secretion ratios by splenocytes, suggesting that SP has strong and MP has mild anti-inflammation potential via modulating cytokine secretion profiles. However, MP treatment at an appropriate concentration in the absence of LPS exhibited an antiapoptotic activity via modulating pro- (Bak) and antiapoptotic (B cell lymphoma 2) protein expression ratios, suggesting that MP may protect primary immune cells from apoptotic cell death. Overall, our findings suggest that SP has better anti-inflammation potential, whereas MP has better cell proliferation and antiapoptotic potential in vitro.  相似文献   
10.
We tried to correlate the in vitro activity and the in vivo efficacy of voriconazole (VRC) and posaconazole (POS) against Aspergillus flavus and Aspergillus niger. The in vitro susceptibility of a large set of isolates was determined by broth microdilution and disk diffusion methods, while the in vivo efficacy was assessed in a murine model of disseminated infection. For A. flavus, VRC showed efficacy even for strains with MICs above the epidemiologic cutoff value (ECV) (1 μg/mL). For A. niger, VRC was ineffective against those strains for which the MIC was 1 dilution below the corresponding ECV (2 μg/mL). POS showed efficacy against all the strains of both species included in the study, although isolates with MICs > ECV were not tested.  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