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   1788篇
  免费   54篇
  国内免费   43篇
教育   1078篇
科学研究   344篇
各国文化   1篇
体育   249篇
综合类   164篇
文化理论   4篇
信息传播   45篇
  2024年   2篇
  2023年   3篇
  2022年   39篇
  2021年   55篇
  2020年   41篇
  2019年   32篇
  2018年   16篇
  2017年   20篇
  2016年   22篇
  2015年   51篇
  2014年   104篇
  2013年   109篇
  2012年   135篇
  2011年   131篇
  2010年   103篇
  2009年   94篇
  2008年   97篇
  2007年   134篇
  2006年   131篇
  2005年   116篇
  2004年   93篇
  2003年   63篇
  2002年   50篇
  2001年   63篇
  2000年   33篇
  1999年   35篇
  1998年   19篇
  1997年   26篇
  1996年   25篇
  1995年   10篇
  1994年   9篇
  1993年   8篇
  1992年   9篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1987年   1篇
排序方式: 共有1885条查询结果,搜索用时 15 毫秒
131.
颈椎病的体育疗法   总被引:1,自引:0,他引:1  
以体疗为主,辅以推拿治疗颈椎病507例,取得了良好效果。  相似文献   
132.
目的探讨自主运动调节tau蛋白激酶和tau蛋白磷酸酶的基因表达,抑制APP/PS1转基因小鼠海马tau蛋白过度磷酸化,进而改善学习记忆能力的分子机制。方法C57系APP/PS1转基因小鼠随机分为运动组(TE)与对照组(TC);C57系野生小鼠亦随机分为运动组(E)与对照组(C)。其中,TE组和E组小鼠从3月龄开始,给予16周的跑轮运动装置,TC组和C组小鼠不施加运动干预,作为相应对照组。Morris水迷宫实验检测APP/PS1转基因小鼠的空间学习记忆能力,Western Blot实验检测海马磷酸化tau蛋白(P-tau)水平,RT-PCR实验检测海马tau蛋白及tau蛋白激酶GSK-3β和CDK-5,tau蛋白磷酸酶PP2A和PP1 mRNA表达。结果(1)与TC组相比,TE组小鼠Morris水迷宫游泳潜伏期显著性降低(P<0.05),平台象限的游泳时间百分比显著性增加(P<0.05),穿越原平台位置的次数极显著性增加(P<0.01);(2)与TC组相比,TE组小鼠海马总tau蛋白mRNA表达显著下调(P<0.05),Ser202位点和Thr181位点P-tau蛋白表达均显著性下调(P<0.05);(3)与TC组相比,TE组小鼠海马tau蛋白磷酸化激酶GSK-3β(P<0.01)和CDK-5(P<0.05)mRNA表达显著性下调,tau蛋白磷酸酶PP2A(P<0.01)和PP1(P<0.01)mRNA表达极显著性下调。结论16周自主运动通过下调tau蛋白激酶表达、上调tau蛋白磷酸酶表达,抑制APP/PS1转基因小鼠海马tau蛋白的过度磷酸化,进而促进海马神经细胞功能,改善转基因小鼠学习记忆。说明自主运动可通过调节脑的分子生物学机制,促进认知功能的改善和提升,预防和缓解阿尔茨海默病。  相似文献   
133.
To elucidate a higher rate of premature cardiovascular disease (CVD) in Asian Indian descendants (Roma) in Slovakia, we investigated frequency distribution, correlates and relationship of lipoprotein(a) [Lp(a)] to family CVD risk factors in Roma children and their Caucasian neighbors. The study sample consisted of 607 healthy children aged 7–18 years (55% Roma, 48% male) as part of the biracial (Roma–Caucasian) Slovak Lipid Community Study. Overall, frequency distribution data of Lp(a) were highly skewed to low concentrations, with markedly higher Lp(a) levels in Roma than in Caucasian children (median and range, mg/dL: 14.5; 0–159.2 vs 6.2; 0–112.3, P < 0.001), regardless of age and gender. Lp(a) was positively correlated with apo B (0.159, P = 0.004) in Roma, and LDL cholesterol (0.170, P = 0.005) in Caucasian children. In addition, daily income of the family was negatively related with Lp(a) in Roma (−0.134, P = 0.036) while positively in Caucasians (0.136, P = 0.047). For both race groups, no significant association was found between Lp(a) and age, body mass index, mean arterial pressure, smoking, and physical activity. Also, no significant relationships were examined between serum Lp(a) levels >30 mg/dL in children and family CVD risk factors, except for diabetes mellitus in parents of Caucasian origin (OR 4.46; 95%CI: 1.23–16.20). In a multivariate analysis, daily income, LDL cholesterol or apo B explained ~7% of the variance of Lp(a). This study suggests a significantly higher serum Lp(a) levels in Roma than in Caucasian children and a small effect, in general, of relevant CVD risk factors on the variation of Lp(a) levels in childhood.  相似文献   
134.
通过分析医学留学生的学习特点,总结肾内科专业留学生教学经验,探讨多媒体教学在留学生教学工作的优势,以利于更好地开展留学生教学工作,提高教学质量。  相似文献   
135.
细胞生物学是生命科学的重要基础学科,是生物科学、生物工程专业必修课程之一.在更新教学内容、优化知识结构、改革教学方法和组织课堂讨论等方面进行了探索和改进,提高了教师的教学质量和学生的学习积极性.  相似文献   
136.
以深圳"山寨机"为例,分析了山寨机出现的经济原因、政策原因、技术原因、价格原因、产业链原因、产品推出速度原因、外观设计原因、功能原因、利益链重构原因,指出了"山寨化"的深层次根源在于中国产业的"三元化",分析了"山寨机"面临的市场困境、价格困境、技术困境、信任困境、品牌困境、生存困境,并在此基础上提出山寨厂商、行业协会、政府部门应各负其责、营造更好产业成长环境的未来出路。  相似文献   
137.
为加强和优化医学细胞生物学教学,促进教育从应试型向素质型转变,对学生成绩的考核进行了改革,采用一种新的综合考核方式。结果表明,82.2%的同学赞同这种考试形式的改革,认为起到了加强素质教育的作用。此外,还对进一步完善这种考试形式的改革进行了讨论,并提出了建议。  相似文献   
138.
Chromophobe renal cell carcinoma(ChRCC) metastatic to the testis has not,to the best of our knowledge,been reported in the literature.Nor have there been reports of delayed bilateral adrenal metastasis of ChRCC.Here we report a case of metachronous contralateral testicular and bilateral adrenal metastasis of ChRCC in a 70-year-old man who underwent right radical nephrectomy for RCC six years ago.He was admitted to the hospital because of left intrascrotal enlargement of two-month duration.Ultrasonography re...  相似文献   
139.
Mesenchymal stem cell(MSC)transplantation has shown a therapeutic potential to repair the ischemic and infracted myocardium,but the effects are limited by the apoptosis and loss of donor cells in host cardiac microenvironment.The aim of this study is to explore the cytoprotection of heat shock protein 90(Hsp90)against hypoxia and serum deprivation-induced apoptosis and the possible mechanisms in rat MSCs.Cell viability was determined by3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay.Apoptosis was assessed by Hoechst 33258nuclear staining and flow cytometric analysis with annexin V/PI staining.The gene expression of Toll-like receptor-4(TLR-4)and V-erb-b2 erythroblastic leukemia viral oncogene homolog 2(ErbB2)was detected by real-time polymerase chain reaction(PCR).The protein levels of cleaved caspase-3,Bcl-2,Bcl-xL,Bax,total-ERK,phospho-ERK,totaI-Akt,phospho-Akt,and Hsp90 were detected by Western blot.The production of nitric oxide was measured by spectrophotometric assay.Hsp90 improves MSC viability and protects MSCs against apoptosis induced by serum deprivation and hypoxia.The protective role of Hsp90 not only elevates Bcl-2/Bax and Bcl-xL/Bax expression and attenuates cleaved caspase-3 expression via down-regulating membrane TLR-4 and ErbB2 receptors and then activating their downstream PI3K/Akt and ERK1/2 pathways,but also enhances the paracrine effect of MSCs.These findings demonstrated a novel and effective treatment strategy against MSC apoptosis in cell transplantation.  相似文献   
140.
In this paper,we investigate the effect and the possible mechanism of high glucose levels on the calcification of human aortic smooth muscle cells (HASMCs).HASMCs were divided into four groups: normal glucose group (NG),osmolality control group (OC),high glucose group (HG,HASMCs culture medium containing 30 mmol/L glucose),and high glucose plus recombinant human Noggin protein (bone morphogenetic protein-2 (BMP-2) antagonist) group (HN).The mRNA levels and the protein expressions of BMP-2 and core binding factor alpha-1 (Cbfα-1) were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot.After induced by 10 mmol/L β-glycerol phosphoric acid,cells were harvested for assessments of alkaline phosphatase (ALP) activities at Days 1,2,and 3,and intracellular calcium contents at Days 7 and 14,respectively.High glucose levels increased the mRNA levels and the protein expressions of BMP-2 and Cbfα-1 (P0.05).The expression of Cbfα-1 was partially blocked by Noggin protein (P0.05),while BMP-2 was not (P0.05).After being induced by β-glycerol phosphoric acid,high glucose levels increased the ALP activity [(48.63±1.03) vs.(41.42±2.28) U/mg protein,Day 3;P0.05] and the intracellular calcium content [(2.76±0.09) vs.(1.75±0.07) μmol/mg protein,Day 14;P0.05] in a time-dependent manner when compared with the NG group,while the ALP activity could not be blocked by Noggin protein [(48.63±1.03) vs.(47.37±0.97) U/mg protein,Day 3;P0.05].These results show that high glucose levels can evoke the calcification of HASMCs by inducing osteoblastic trans-differentiation and intracellular calcium deposition via the BMP-2/Cbfα-1 pathway,which can be partially blocked by Noggin protein.  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