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   220篇
  免费   2篇
教育   150篇
科学研究   45篇
各国文化   4篇
体育   6篇
信息传播   17篇
  2023年   5篇
  2022年   10篇
  2021年   9篇
  2020年   10篇
  2019年   14篇
  2018年   14篇
  2017年   14篇
  2016年   11篇
  2015年   8篇
  2014年   15篇
  2013年   31篇
  2012年   11篇
  2011年   13篇
  2010年   11篇
  2009年   4篇
  2008年   7篇
  2007年   6篇
  2006年   5篇
  2005年   5篇
  2004年   2篇
  2003年   4篇
  2002年   1篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   2篇
  1995年   3篇
  1990年   2篇
  1987年   1篇
排序方式: 共有222条查询结果,搜索用时 0 毫秒
21.
目的:探究桑螵蛸脂类提取物的成分及对铜绿假单胞菌的抗菌和抗生物膜作用。创新点:中国传统中药桑螵蛸一直广泛应用于肾病的治疗,在抗菌领域未见报道,本实验首次证明桑螵蛸脂类提取物对铜绿假单胞菌有明显的抗菌和抗生物膜作用。方法:采用气相色谱-质谱联用技术,测定桑螵蛸脂质提取物的化学成分及其相对比例。采用纸片扩散法和琼脂平板稀释法观察桑螵蛸脂类提取物对铜绿假单胞菌的抑菌效应并测定最小抑制浓度(MIC)。采用结晶紫染色法和扫描电镜(SEM)进行抑制生物被膜的试验。结论:桑螵蛸脂类提取物中含有16种化合物,最丰富的成分分别是倍半萜类化合物、单萜和微量芳香族化合物。桑螵蛸脂类提取物对铜绿假单胞菌的MIC为4 mg/ml,对铜绿假单胞菌生物被膜的抑制作用明显。  相似文献   
22.
23.
We report physicochemical characteristics of various kinds of liquid milk commercially available in Pakistan in comparison with those of fresh natural milk from animals. Milk samples were collected from local markets at Peshawar, Pakistan,and analyzed for their physical features, including moisture, total solids, specific gravity, conductivity, viscosity and titratable acidity (lactic acid equivalent), and chemical components and macro-minerals, including total protein, casein, lactose, ash and minerals (Na, K and Mg). These items were compared with the physicochemical characteristics of the fresh natural milk samples from buffalo, cow and goat. The results were also compared with reported nutritional quality of milk from various countries and World Health Organization (WHO) standards. We found that all the physical features and chemical components of commercially available milk in Pakistan markets meet WHO's requirements, except for Na, K, Ca and Mg, which are below the standards.  相似文献   
24.
25.
The correlation between antioxidant capacity and oxidative damage during aging has been reported in several tissues in different species. Glutathione-S-transferases (GST) can metabolise endogenous and exogenous toxins and carcinogens by catalysing the conjugation of diverse electrophiles with reduced glutathione (GSH). We observe a significant (P < 0.001) increase in plasma GST activity as a function of human age (r = 0.5675). A significant (P < 0.001) positive correlation (r = 0.8979) is observed between GST activity and total plasma antioxidant potential measured as ferric reducing ability of the plasma (FRAP). GST activity and red cell intracellular GSH also show a significant positive correlation (r = 0.7014). We hypothesize that the increased activity of plasma GST is a manifestation of increased generation of ROS and a concomitant decrease in the level of plasma antioxidant capacity during aging.  相似文献   
26.
The purpose of the present study is to investigate mathematics anxiety among 220 sixth through eighth grade Turkish students in terms of mathematics achievement levels, perceived enjoyment of the mathematics teaching method, perceived enjoyment of mathematics, and perceived help with mathematics from parents. The Mathematics Anxiety Scale for Primary School Students (Bindak, 2005) was used to assess the levels of mathematics anxiety. A 3 × 2 factorial analysis of variance results showed that there was not a significant interaction effect or main effect of gender; however, there was a significant main effect of grade level. Standard multiple regression analyses show that independent variables accounted for 63% to 70% of variability in the dependent variable. The results also indicate that not only the perceived enjoyment of mathematics, but also the enjoyment of the mathematics teaching method and help with mathematics from parents had a significant effect on mathematics anxiety.  相似文献   
27.
Pleurotus sajor-caju (Fr.) Singer was cultivated on selected agro wastes viz. cotton stalks, groundnut haulms, soybean straw, pigeon pea stalks and leaves and wheat straw, alone or in combinations. Cotton stalks, pigeon pea stalks and wheat straw alone or in combination were found to be more suitable than groundnut haulms and soybean straw for the cultivation. Organic supplements such as groundnut oilseed cake, gram powder and rice bran not only affected growth parameters but also increased yields. Thus bioconversion of lignocellulosic biomass by P. sajor-caju offers a promising way to convert low quality biomass into an improved human food.  相似文献   
28.
The research questions addressed in this study were: what types of epistemological beliefs do elementary students have; what types of metacognition do elementary students have; and what are the relationships among students’ perceived characteristics of constructivist learning environment, metacognition, and epistemological beliefs. A total of 626 students enrolled in sixth, seventh, and eight grades of nine elementary public schools located in Ankara, Turkey constituted the participants of this study. Constructivist learning environment survey (CLES), Junior metacognitive awareness inventory (Jr. MAI), and Schommer epistemological belief questionnaire (EB) were administered to students. Factor Analysis of Jr. MAI revealed both knowledge of cognition and regulation of cognition items were loaded into one factor. Confirmatory factor analysis of EB revealed a four factor structure namely innate ability, quick learning, omniscient authority, and certain knowledge. Regression analyses revealed that metacognition and omniscient authority were significant predictors of personal relevance dimension of CLES. Metacognition was found as the only predictor of the student negotiation. Innate ability and metacognition significantly contributed to uncertainty. This study revealed that the elementary students with different mastery levels hold different epistemological beliefs and multi-faceted nature of elementary school students’ metacognition was seemed to be supported with this study. It was found that metacognition contributed to model more than epistemological beliefs for all three dimensions of CLES.  相似文献   
29.
The troubled state of affairs in the Federally Administered Tribal Areas (FATA) of Pakistan portends serious repercussions and grave consequences, destined to affect education particularly higher education in the entire tribal belt. Ironically, no extensive study has been conducted, to investigate those dimensions of FATA higher education which have been adversely affected in the aftermath of 9/11. This exploratory study examines those areas which have been badly affected as a result of current turmoil. In fact, the higher education in FATA has its own peculiar dynamics. Inherently, the entire tribal region has very few well-maintained and properly equipped colleges. Lack of adequate educational facilities, multiplied poor security environment has aggravated the entire situation. Law and order situation in the region has undermined the already dilapidated monitoring mechanism of education department. This state of affairs provides breeding ground for extremist propensities and radical tendencies. In reality, very little attention has been devoted to reform the education system in tribal areas. The whole set up needs to be rehabilitated by taking recourse due to the proactive role of international community. The paper concludes with recommendations for policy makers besides offering new avenues for further research.  相似文献   
30.
local government authorities (LGAs) are organised around operational structures with business processes spanning within departments and across other government organisations. In such an organisational setting, the harmonisation of Information Technology (IT) operations, integration of cross-departmental processes and the underlying Information Systems (IS) signifies a challenge in delivering integrated services. This paper attempts to explore enterprise application integration (EAI) adoption in the UK local government authorities (LGAs). Despite the hype of EAI adoption in private domain, its application in LGAs is inadequate as there is a lack of adoption models/frameworks that can be used by the public sector. The context of the study is to consider the transformation of IT infrastructure management and operations with EAI technologies. The empirical findings, generated through a detailed case analysis, manifestly exemplify that EAI predominantly acts as a ‘back-office’ technology that facilitates operations by developing a flexible and maintainable integrated IT infrastructure. Our proposed framework is believed to be imperative and unique as it provides a more systematic way to examine the adoption of integration technologies, extends the established norms for EAI adoption by utilising a prioritisation technique to classify the importance of factors. The contribution of the research extends the literature on EAI and identifies theoretical and practical opportunities that facilitate LGAs in their decision-making process to produce more robust proposals for EAI adoption.  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