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   3299篇
  免费   173篇
  国内免费   59篇
耳鼻咽喉   151篇
儿科学   24篇
妇产科学   25篇
基础医学   455篇
口腔科学   30篇
临床医学   90篇
内科学   228篇
皮肤病学   64篇
神经病学   99篇
特种医学   23篇
外国民族医学   2篇
外科学   1618篇
综合类   201篇
预防医学   93篇
眼科学   24篇
药学   150篇
中国医学   50篇
肿瘤学   204篇
  2024年   6篇
  2023年   29篇
  2022年   70篇
  2021年   95篇
  2020年   66篇
  2019年   97篇
  2018年   83篇
  2017年   94篇
  2016年   70篇
  2015年   78篇
  2014年   202篇
  2013年   149篇
  2012年   104篇
  2011年   217篇
  2010年   227篇
  2009年   213篇
  2008年   204篇
  2007年   287篇
  2006年   266篇
  2005年   150篇
  2004年   173篇
  2003年   155篇
  2002年   121篇
  2001年   51篇
  2000年   45篇
  1999年   35篇
  1998年   25篇
  1997年   17篇
  1996年   13篇
  1995年   20篇
  1994年   13篇
  1993年   11篇
  1992年   12篇
  1991年   9篇
  1990年   11篇
  1989年   10篇
  1988年   9篇
  1987年   3篇
  1986年   3篇
  1985年   12篇
  1984年   20篇
  1983年   9篇
  1982年   6篇
  1981年   8篇
  1980年   7篇
  1979年   5篇
  1978年   4篇
  1976年   6篇
  1973年   4篇
  1971年   2篇
排序方式: 共有3531条查询结果,搜索用时 15 毫秒
1.
目的:探讨miR-26b参与原发性肝细胞肝癌(HCC)侵袭的机制。方法:在细胞培养液中培养人肝细胞系HL-7702和HCC细胞各系Hepb-3、HuH-7、MHCC97-L、MHCC97-H。实时荧光定量PCR法(qRT-PCR)检测miR-26b的表达水平;用miR-26b mimics、miR-26b inhibitors和Notch1-siRNA分别转染HCC细胞;MTT实验检测转染后HCC细胞的活力;采用Western blot检测Notch1受体蛋白表达水平的变化;Transwell小室测定不同处理后的HCC细胞的侵袭能力。结果:人正常肝细胞系HL-7702和HCC细胞系Hepb-3、HuH-7、MHCC97-L、MHCC97-H中的miR-26b相对表达含量随其侵袭和迁移能力的升高而依次下降;抑制miR-26b的表达,Notch1受体蛋白表达明显增高,而此时HCC细胞的侵袭性显著增强;相反,上调miR-26b的表达,Notch1受体蛋白表达明显降低,而HCC细胞侵袭性显著下降;miR-26b可能通过调控Notch1信号通路调节HCC细胞侵袭性。结论:miR-26b通过负调控Notch1信号通路抑制HCC细胞侵袭能力,为HCC侵袭的机制奠定了理论基础,miR-26b可能成为HCC治疗的新靶点。  相似文献   
2.
Syphilis is a sexually transmitted disease caused by Treponema pallidum. Syphilitic aortitis might coexist in a dysfunctional aortic valve, but the etiology remains unclear, because microbiological diagnosis is difficult. A 62-year-old man with low-grade fever was diagnosed with aortitis and infective endocarditis, due to Treponema pallidum infection, using polymerase chain reaction analysis. This case suggests that syphilis might cause infective endocarditis.  相似文献   
3.
目的对膝关节前外侧韧带(anterolateral ligament,ALL)的研究进展进行综述,为临床诊治提供参考。方法广泛查阅近年来国内外有关 ALL 损伤诊断及治疗的文献,总结膝关节 ALL 解剖形态、生物力学以及 ALL 损伤机制、治疗现状。结果膝关节 ALL 具有限制胫骨内旋及前移作用,影响膝关节轴移。ALL 损伤后可结合患者体征和 MRI 检查诊断。膝关节 ALL 手术指征尚未统一,但多数学者倾向于对需进行前交叉韧带(anterior cruciate ligament,ACL)重建或翻修且伴有高度轴移试验阳性的患者进行 ALL 重建。目前 ALL 重建方式较多,但尚无最佳治疗术式。此外,由于缺乏高质量的术后长期随访研究,远期临床疗效仍不明确。结论ALL 在维持膝关节稳定性方面具有一定作用,但 ALL 重建技术及临床疗效仍待进一步研究。  相似文献   
4.
从内蒙古呼伦贝尔草原的盐碱湖中分离到的一株低度嗜盐嗜碱细菌Bacillus sp F26,能积累高水平过氧化氢酶(CAT)。对Bacillus sp F26发酵产过氧化氢酶的环境与营养条件的研究结果表明,其积累高水平过氧化氢酶的适宜环境条件为:温度37℃,种龄20-22h,接种量5%,装液量50mL/(250mL的摇瓶)。适宜发酵培养基组成(g/L)为:葡萄糖15,牛肉膏10,玉米浆10,酵母膏5,磷酸二氢钾1,氯化镁0.2,氯化钠50,碳酸钠10。采用上述条件进行摇瓶分批发酵实验,发酵20h,过氧化氢酶酶活达到16.32U/mL,细胞干重为4.12g/L。进一步研究发现,在对数生长后期(16h)添加2mmol/L的H2O2可以明显刺激产酶,在5L的发酵罐上进一步以指数速率方式流加H2O2,由于该流加方式可降低H2O2对细胞的毒害作用,过氧化氢酶酶活达到29.89U/mL,与分批发酵相比提高了92.8%。  相似文献   
5.
目的研究17β-雌二醇(17β-E2)对子宫内膜异位症(内异症)患者在位子宫内膜间质细胞β-catenin mRNA和蛋白表达的影响,探讨Wnt/β-catenin信号通路在介导雌激素促进内异症发生发展的作用。方法体外分离培养内异症患者在位子宫内膜间质细胞。用不同浓度17β-E2处理子宫内膜间质细胞48 h;此后选用10-10mol/L 17β-E2处理子宫内膜间质细胞12、24和48 h,逆转录聚合酶链反应(RT-PCR)和免疫印迹法(Western blotting)检测17β-E2处理前后子宫内膜间质细胞β-catenin mRNA和蛋白的表达水平。同法分析雌激素受体拮抗剂ICI182,780(10-6mol/L)对17β-E2促进β-catenin mRNA和蛋白表达的影响。免疫组织化学染色观察17β-E2作用后β-catenin在子宫内膜间质细胞中的定位。结果17β-E2能明显促进内异症患者在位子宫内膜间质细胞β-catenin mRNA和蛋白的表达,并呈剂量和时间依赖性,于10-10mol/L作用48 h最明显。雌激素受体拮抗剂ICI182,780能明显抑制17β-E2对子宫内膜间质细胞β-catenin mRNA和蛋白的表达。免疫组织化学染色发现17β-E2能促进β-catenin在子宫内膜间质细胞核内的表达。结论雌激素可能通过激活Wnt/β-catenin信号通路促进内异症在位子宫内膜的异位种植。  相似文献   
6.
Electrochemotherapy is a novel antitumor treatment involving the systemic administration of bleomycin followed by the delivery of electrical pulses to the tumor. The present study investigates the effects of electrochemotherapy on the growth of colon 26 cells inoculated subcutaneously into the backs of BALB/c mice. The mice were divided into the following four experimental groups: 20 that received no further treatment after the inoculation of colon 26 cells (control group); 20 that received 500 μg of bleomycin intraperitoneally 7 and 9 days after the inoculation (BLM group); 20 that received electric pulses to the tumor 7 and 9 days after the inoculation (EP group); and 30 that received electrochemotherapy 7 and 9 days after the inoculation (ECT group). During 28 days of observation, no deaths due to tumor progression occurred in the ECT group, but there were 18 in the control group, 11 in the BLM group, and 18 in the EP group. While weight loss was observed in all groups, it was most remarkable in the control group. Tumor growth was significantly inhibited in the ECT group, compared to the other experimental groups (P<0.01). The results of this study demonstrated that electrochemotherapy significantly inhibited the growth of colon 26 tumors in mice, without causing any remarkable adverse effects.  相似文献   
7.
The objective of this investigation was to demonstrate the possible interactions of systemic lidocaine (lido) with inhibitory receptors in the spinal cord. In the lumbar dorsal horn of anesthetized and curarized rats, 60 physiologically identified, wide dynamic range (WDR) neurons, were recorded extracellularly. Glutamate, glycine and its selective antagonist, strychnine, were iontophoretically applied onto the neurons either singularly or concurrently. The effects of systemic lido on the drug-induced frequency changes and the interaction with the glycine receptors, using strychnine as a probe, were studied. It was consistently found that (i) lido (3–4 mg/kg) inhibited the excitatory responses to iontophoretic glutamate, (ii) this inhibition was significantly antagonized by concurrent iontophoretic strychnine, (iii) iontophoretic glycine induced comparable glutamate inhibition that was reversed by strychnine. In contrast, no effect on glutamate-induced excitations was observed when lido was applied by micropressure or a different local anesthetic was systemically administered. The results suggest that central inhibitory effects of lido could by mediated by spinal strychnine-sensitive glycine receptors, activated by lido itself or possibly by its glycine residue-bearing metabolites.  相似文献   
8.
目的探讨CD26/DPPⅣ、半乳糖凝集素3免疫组织化学染色及其联合检测在甲状腺癌诊断中的应用价值。方法采用免疫组织化学EnVision二步法检测了114例良恶性甲状腺肿瘤组织中CD26/DPPⅣ及半乳糖凝集素3的表达。结果CD26/DPPⅣ及半乳糖凝集素3在正常甲状腺组织中无表达,在甲状腺腺瘤及滤泡癌中少有表达,在大多数甲状腺乳头状癌中呈不同程度的阳性表达。相对于甲状腺腺瘤而言,CD26/DPPⅣ诊断乳头状癌的敏感性、特异性、诊断准确率、阳性预测值、阴性预测值及kappa值分别为86.8%、97.2%、90.4%、98.3%.79.5%及0.80,半乳糖凝集素3分别为97.1%、91.7%、95.2%、95.7%、94.3%及0.89。结论CD26/DPPⅣ及半乳糖凝集素3均是甲状腺乳头状癌较为可靠的标志物,可以辅助常规的病理检查进行乳头状癌与腺瘤的鉴别诊断,它们在甲状腺滤泡癌诊断中的应用价值尚有待于进一步的研究。  相似文献   
9.
A prospective clinical and radiographic study was conducted in order to compare Hydron and laterally condensed gutta-percha/AH-26 root canal fillings. Paralleling technique periapical radiographs were taken preoperatively, postoperatively and at recall appointments at post-treatment intervals of 6 months, 1 year, 2 years, 3 years and 5 years. Clinical examination at the recall appointments revealed no adverse signs or symptoms amongst all the patients who attended (mean attendance 44.5% at each interval). Radiographs were scored according to the periapical status of the treated root, and comparable bone healing rates were observed between the two root-filling materials. Among the patients attending recall appointments, there were no radiographic signs of failure of any of the 39 gutta-percha/AH-26 root canal fillings. However, three of the 35 canals filled with Hydron were classified as failures, and four required further assessment after the 5-year recall appointment. This study indicated that Hydron and gutta-percha/AH-26 root canal fillings were well accepted but, on the basis of radiographic assessment, success with gutta-percha/AH-26 was more predictable.  相似文献   
10.
HLA-A26等位基因与银屑病环境危险因素的交互作用   总被引:1,自引:0,他引:1  
目的:研究银屑病HLA-A26等位基因与环境危险因素之间的交互作用。方法:采用病例对照研究方法,调查190例银屑病患者及同一地区的健康对照191例,用多聚酶链反应-序列特异性引物(PCR-SSP)方法进行HLA-A26等位基因检测,对银屑病的环境危险因素及与HLA-A等位基因间交互作用进行研究。结果:(1)受潮、感染、外伤、嗜酒、吸烟、食鱼虾、药物和精神紧张均为银屑病的环境危险因素。(2)与正常对照组相比,HLA-A26等位基因与银屑病呈显著正相关(P<0.001)。(3)HLA-A26等位基因与受潮、嗜酒和食鱼虾存在显著交互作用。结论:HLA-A26等位基因似能增加受潮、嗜酒和食鱼虾发生银屑病的易患性。  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