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   4550篇
  免费   353篇
  国内免费   311篇
耳鼻咽喉   50篇
儿科学   55篇
妇产科学   47篇
基础医学   389篇
口腔科学   44篇
临床医学   640篇
内科学   475篇
皮肤病学   27篇
神经病学   159篇
特种医学   169篇
外国民族医学   1篇
外科学   340篇
综合类   1157篇
现状与发展   1篇
预防医学   397篇
眼科学   52篇
药学   548篇
  5篇
中国医学   63篇
肿瘤学   595篇
  2024年   7篇
  2023年   67篇
  2022年   127篇
  2021年   169篇
  2020年   113篇
  2019年   96篇
  2018年   82篇
  2017年   97篇
  2016年   118篇
  2015年   182篇
  2014年   393篇
  2013年   343篇
  2012年   368篇
  2011年   413篇
  2010年   389篇
  2009年   355篇
  2008年   217篇
  2007年   301篇
  2006年   360篇
  2005年   244篇
  2004年   223篇
  2003年   137篇
  2002年   112篇
  2001年   83篇
  2000年   47篇
  1999年   49篇
  1998年   26篇
  1997年   26篇
  1996年   13篇
  1995年   12篇
  1994年   18篇
  1993年   10篇
  1992年   3篇
  1991年   4篇
  1990年   4篇
  1989年   5篇
  1988年   1篇
排序方式: 共有5214条查询结果,搜索用时 484 毫秒
1.
目的:克隆人肠道病毒71型(EV71)及柯萨奇病毒A组16型(CA16)的VP1蛋白编码基因,构建相应真核表达质粒在体外进行重组表达,检测其细胞内定位,为EV71及CA16的疫苗研究提供基础。方法:通过PCR扩增分别获取EV71及CA16的VP1编码序列,插入pcFlag载体,分别构建EV71及CA16 VP1与FLAG标签融合的真核表达质粒;瞬时转染人胚肾293T细胞及横纹肌肉瘤RD细胞,Western blot法检测融合蛋白的表达,免疫荧光检测融合蛋白的细胞内定位情况。结果:测序表明两种来源VP1蛋白的重组表达质粒构建正确;分别转染两种不同的细胞后,均可通过Western blot检测到相应蛋白表达;免疫荧光检测显示两种毒株的VP1均表达在细胞质中。结论:外源融合表达EV71或CA16 VP1蛋白的真核表达质粒构建成功;所构建质粒分别转染细胞后,均可在细胞质内检测到VP1融合蛋白的表达。  相似文献   
2.
BackgroundPeriodontitis is associated with the pathogenesis of atherosclerotic plaque, and hypersensitive C reactive protein (hs-CRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2) are the serum biomarkers of the stability of atherosclerotic plaque. Whether periodontitis is associated with the serum level of hs-CRP and Lp-PLA2 of acute ischemic stroke remains unclear.Material and MethodsWe recruited 103 cases with acute ischemic stroke within 7 days after stroke onset. Pocket depth and clinical attachment loss were assessed by oral examination to define the severe periodontitis. Demographic information including gender, age and body weight index, income level, education level, past medical history include smoking history, drinking history, ischemic stroke history, coronary heart disease, hypertension, diabetes and hyperlipidemia were collected, and serum biomarkers including white blood cell (WBC), fibrinogen, total cholesterol (TC), triglyceride (TG), lower density lipoprotein (LDL-C), high density lipoprotein (HDL-C), hs-CRP, HemoglobinA1c (HbAlc), Homocysteine (HCY) and Lp-PLA2 were tested.Results65 (63.1%) cases were diagnosed as severe periodontitis. Severe periodontitis group showed more male, age, drinking history, higher levels of hs-CRP and Lp-PLA2. Multivariate logistic regression showed that severe periodontitis was were significantly associated with hs-CRP (OR = 2.367, 95%CI: 1.182–4.738; P = .015) and Lp-PLA2 (OR = 2.577, 95% CI: 1.010–6.574; P = .048).ConclusionsSevere periodontitis is independently associated with the serum Level of hs-CRP and Lp-PLA2 in patients with acute ischemic stroke. Whether the improvement of periodontitis could decrease the occurrence and re-occurrence of ischemic stroke by stablizating atherosclerotic plaque need be further studied in future.  相似文献   
3.
Chemical exchange saturation transfer (CEST) MRI is sensitive to labile proton concentration and exchange rate, thus allowing measurement of dilute CEST agent and microenvironmental properties. However, CEST measurement depends not only on the CEST agent properties but also on the experimental conditions. Quantitative CEST (qCEST) analysis has been proposed to address the limitation of the commonly used simplistic CEST‐weighted calculation. Recent research has shown that the concomitant direct RF saturation (spillover) effect can be corrected using an inverse CEST ratio calculation. We postulated that a simplified qCEST analysis is feasible with omega plot analysis of the inverse CEST asymmetry calculation. Specifically, simulations showed that the numerically derived labile proton ratio and exchange rate were in good agreement with input values. In addition, the qCEST analysis was confirmed experimentally in a phantom with concurrent variation in CEST agent concentration and pH. Also, we demonstrated that the derived labile proton ratio increased linearly with creatine concentration (P < 0.01) while the pH‐dependent exchange rate followed a dominantly base‐catalyzed exchange relationship (P < 0.01). In summary, our study verified that a simplified qCEST analysis can simultaneously determine labile proton ratio and exchange rate in a relatively complex in vitro CEST system. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
4.
近几年来,诚信缺失现象大量涌现,信用问题日益凸现,医疗行业也深陷其中。医患诚信问题严重地挫伤了医患感情,医患间不信任情绪不断加深。关注和研究我国医患关系中的诚信伦理问题已刻不容缓。  相似文献   
5.
应用可吸收钉棒治疗关节内骨折   总被引:5,自引:0,他引:5  
目的探讨可吸收钉、棒治疗关节内骨折的效果。方法1998年6月~2004年8月,应用自身增强一聚乙酯(self-reinforced polyglycolic acid,SR—PGA)、自身增强一聚丙酯(self—reinforced poly—L—Lacticacid,SR—PLLA)可吸收螺钉、棒,手术治疗关节内骨折35例,其中男30例,女5例。年龄4~62岁。均为关节内或关节周围松质骨骨折。手术时间为伤后3h~29d。应用SR—PGA全螺纹钉9枚,SR—PLLA拉力螺钉26枚,SR—PLLA固定棒15枚。术后行骨牵引或石膏外固定。结果患者术后获随访3~60个月,平均28个月,伤口均Ⅰ期愈合;骨折于1~3个月内达临床愈合,无再移位、感染及局部积液。患者关节功能恢复满意。根据美国骨科协会(AASO)关节功能评价:优26例,良7例,可1例,差1例,优良率94.3%。结论可吸收内固定钉、棒治疗关节内及关节周围骨折,免除了患者二次手术取出内固定物的痛苦,是一种有效和较为理想的方法。  相似文献   
6.
BACKGROUND: The ubiquitin-proteasome system (UPS) is thought to be functionally active in atherosclerosis (AS) lesions. Aspirin was found to be a potent inhibitor of the UPS in some tumour studies; however, its effect on AS remains to be demonstrated in vivo. METHODS: New Zealand rabbits were placed on a normal diet (N) or on a normal diet with aspirin (NI) or on an atherogenic diet without (H) or with aspirin (HI) for 12 weeks. Proteasome activity, concentrations of plasma lipids and levels of peroxidation were determined. Ubiquitin/ubiquitin-conjugates (Ub), IkappaBalpha, phosphorylated IkappaB (pIkappaBalpha) and p65 were investigated by Western blotting or immunochemistry. RESULTS: Concentrations of plasma lipids and peroxidation levels were higher in H or HI vs. N or NI. Histological analysis showed that atheroma was increased in H. Ub and IkappaBalpha were mainly localised in subendothelium and media vascular smooth muscle cells. Western blots revealed that Ub, IkappaBalpha, and pIkappaBalpha were increased, whereas p65 was lower in HI vs. H. The activity of the 20S proteasome was functionally active in H vs. N, NI or HI, while the 26S proteasome was not affected in any of the groups. CONCLUSIONS: Aspirin can attenuate the pathogenesis of atheroma formation, the degradation of IkappaBalpha and pIkappaBalpha, and lower the expression of p65, indicating that its therapeutic effects on AS may be via inhibition of the UPS.  相似文献   
7.
HBV两种感染模式患者血清CG、β2—MG测定的意义   总被引:2,自引:0,他引:2  
目的探讨血清ALT、CG、β2-MG浓度变化对HBsAg、HBeAg、HBcAb阳性(A组)及HBsAg、HBeAb、HB鄄cAb阳性(B组)的乙型病毒性肝炎的监测价值。方法将180例HBV感染者按乙型病毒性肝炎感染模式分为A组(94例)和B组(86例)二组,同时选取健康人43例作为对照组。测定血清ALT、CG、β2-MG浓度,采用ELISA法检测HBV标记物;酶法测定ALT;放射免疫法测定CG、β2-MG。结果①与健康对照组比较,A组和B组ALT、CG、β2-MG均有显著性差异(P﹤0.01);②A组ALT、CG、β2-MG与B组比较有显著性差异(P﹤0.01)。结论测定血清CG、β2-MG可较早期、较全面的反映乙肝患者肝脏损伤程度,在临床应用中是具有较强实用性的血清学指标。  相似文献   
8.
蛋白酶激活受体1介导人肺上皮细胞分泌白细胞介素-8   总被引:1,自引:0,他引:1  
目的探讨蛋白酶激活受体1(PAR1)激动肽和凝血酶对人肺上皮细胞白细胞介索-8(IL-8)分泌的影响。方法人肺上皮细胞系A549细胞分别接种于12孔培养板各孔内,并分别用不同浓度的PAR1激动肽SFLLR和反PAR1激动肽RLLFS以及不同浓度的凝血酶和/或凝血酶抑制剂水蛭索进行刺激,刺激时间为2和16h。用ELISA方法检测上清液中的IL-8水平。结果经过16h的培养,SFLLR可引起浓度相关性IL-8的释放增加,增加到300μmol/L时诱导IL-8的释放量比基础分泌量增加了近16倍,RLLFS不能引起IL-8的释放增加。凝血酶也可引起浓度相关性IL-8释放.凝血酶在浓度1kU/L时就可引起IL-8释放量增加,10kU/L时诱导IL-8释放量达高峰,为基础分泌量的7.5倍。水蛭索可以抑制凝血酶对IL-8的释放作用。时间相关曲线表明,PAR1介导的IL-8释放从2h起即可引起增加,16h达高峰。结论PAR1激动肽和凝血酶可促进人肺上皮细胞分泌IL-8,PAR1拮抗剂和凝血酶抑制剂可能具有抗炎作用。  相似文献   
9.
小儿癫痫持续状态心肌损伤的初步研究   总被引:5,自引:1,他引:4  
目的 探讨小儿癫痫持续状态是否存在心肌损伤。方法 测定 2 4例全身性惊厥性癫痫持续状态患儿 (试验组 )血清心肌酶谱 (包括AST、CK MB、CK、LDH1、LDH)、心肌肌钙蛋白T(cTnT)、心电图 (ECG) ,并与 2 7例非惊厥持续状态的惊厥儿 (对照组 )进行比较。结果 试验组各心肌酶值 (u/L)为AST 2 77.9± 766.8,CK 1615 .8± 70 2 .3 ,CK MB 70 .3±70 .2 ,LDH1180 .0± 162 .0 ,LDH 619.8± 3 91.9;对照组为AST 83 .6± 163 .7,CK 13 4.6± 12 6.8,CK MB 2 5 .4± 13 .4,LDH171.9± 3 8.8,LDH 3 3 9.2± 2 14 .3 ,两组均值进行比较 ,CK ,CK MB ,LDH ,LDH1差异有统计学意义 ,AST差异无统计学意义 ;cTnT试验组测 13例 ,阳性 6例 ,对照组测 8例均阴性 ,两组比较差异有统计学意义 ;ECG试验组查 2 3例异常 15例 ,对照组查 2 4例异常 4例 ,两组比较差异有统计学意义。结论 小儿全身性惊厥性癫痫持续状态可引起心肌损伤  相似文献   
10.
胫腓骨开放骨折合并动脉损伤的治疗   总被引:1,自引:0,他引:1  
目的 探讨合并血管损伤胫腓骨开放骨折的治疗方法。方法 回顾分析86例(均为单侧肢体)胫腓骨开放骨折合并动脉损伤(Gustilo Ⅲc型)的患者,其中胫前动脉损伤64例,胫后动脉损伤8例,两动脉同时损伤14例。结果 86例全部行急诊清创,血管探查和(或)修补。31例急诊行钢板螺钉内固定术,其中18例术后感染,6例因肢端坏死而截肢;42例行石膏外固定,其中5例术后感染,1例因肢端坏死而截肢;5例行跟骨牵引;8例行外固定架治疗。结论 合并动脉损伤的胫腓骨开放骨折,早期彻底清创至关重要。血管损伤应急诊予以修复,骨折不宜一律内固定。可利用的软组织无张力地覆盖骨、肌腱及血管,残余创面留待Ⅱ期闭合。  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