全文获取类型
收费全文 | 1695篇 |
免费 | 32篇 |
专业分类
教育 | 1323篇 |
科学研究 | 74篇 |
各国文化 | 36篇 |
体育 | 108篇 |
文化理论 | 13篇 |
信息传播 | 173篇 |
出版年
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 36篇 |
2019年 | 47篇 |
2018年 | 44篇 |
2017年 | 56篇 |
2016年 | 48篇 |
2015年 | 43篇 |
2014年 | 34篇 |
2013年 | 435篇 |
2012年 | 39篇 |
2011年 | 49篇 |
2010年 | 44篇 |
2009年 | 38篇 |
2008年 | 45篇 |
2007年 | 39篇 |
2006年 | 41篇 |
2005年 | 57篇 |
2004年 | 42篇 |
2003年 | 27篇 |
2002年 | 45篇 |
2001年 | 26篇 |
2000年 | 36篇 |
1999年 | 22篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 26篇 |
1995年 | 15篇 |
1994年 | 26篇 |
1993年 | 28篇 |
1992年 | 19篇 |
1991年 | 27篇 |
1990年 | 17篇 |
1989年 | 11篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 22篇 |
1979年 | 11篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1973年 | 6篇 |
排序方式: 共有1727条查询结果,搜索用时 15 毫秒
61.
Tomasulo P 《Medical reference services quarterly》2003,22(3):33-38
Natural Standard is a new and extremely easy-to-use database consisting of comprehensive evidence-based medicine monographs, and also news brief's on the subject of complementary/alternative medicine therapies. It does not yet contain a huge amount of material, but it is updated frequently, and new information is continuously added. The focus is on the therapeutic "bottom line" of treatment safety and effectiveness. Dosing, Precautions/Adverse Effects, Pregnancy/Lactation Data, and Interactions information is all clearly displayed along with a "Review of the Evidence" table and a discussion summarizing the overall therapeutic value of the treatment modality. 相似文献
62.
Elizabeth Harrison 《Religious education (Chicago, Ill.)》2013,108(5):179-180
63.
Joyce Harrison 《British Journal of Special Education》1998,25(4):179-183
Joyce Harrison, an educational psychologist in Hampshire, argues that there are many more children with autistic spectrum disorders in mainstream schools than is realised, and suggests that recent research can be used to help class teachers to devise strategies to improve learning opportunities for their pupils. 相似文献
64.
Aims: The aims of this research were to determine the background, education, training experience, roles and responsibilities of practising Clinical Librarians (CL) in the UK. This paper reports the findings of a survey undertaken in 2007 at the third Clinical Librarian conference. This research builds on research undertaken by Harrison and Sargeant in 2002 and Ward in 2004, and can be considered as part of a longitudinal study of the role of the CL in the UK. Objectives: The objectives of the research were to define and gain a broad understanding of the role of the CL in the UK highlighting similarities and differences amongst the professionals and provide evidence for a baseline of skills and activities for the CL role. The type of sampling used was Judgemental. Results/analysis: Results/analysis detail the skills and activities undertaken by CLs. Searching for information for Clinicians was the activity most frequently undertaken. Developing good relationships with other healthcare professionals was considered essential. Two‐thirds of the respondents held a postgraduate library qualification. Conclusions: Crucially a new model for the UK CL role is derived drawing on the findings of this study and the existing literature. 相似文献
65.
Patricia Hausman 《Academic Questions》2008,21(4):392-408
66.
Patricia P. Fritchie 《Publishing Research Quarterly》1989,5(2):65-70
Censorship cases in Florida, Alabama, and Tennessee received international media attention. The events surrounding these cases
at times became very violent and involved many methods of personal and professional intimidation. Informal survey techniques
were used to assess the extent to which these cases would affect the local selection of basal reading textbooks. The results
are reported here, along with recommendations for teachers publishers, and others interested in intellectual freedom.
Patricia P. Fritchie is associate professor of education and director of the Reading Center at Troy State University-Dothan.
She serves as state coordinator, Alabama Reading Association, for the International Reading Association. Dr. Fritchie is very
active in textbook reviews and has served on the State of Alabama's Textbook adoption Committee. 相似文献
67.
Tanya Anne Serry Anne Castles Fiona K. Mensah Edith L. Bavin Patricia Eadie Angela Pezic 《Australian Journal of Learning Difficulties》2015,20(1):83-102
The paper reports on a study designed to develop a risk model that can best predict single-word spelling in seven-year-old children when they were aged 4 and 5. Test measures, personal characteristics and environmental influences were all considered as variables from a community sample of 971 children. Strong concurrent correlations were found between single-word spelling and single-word reading while expressive language and, to a lesser extent, receptive language were less strongly correlated. Predictors of single-word spelling at ages 4 and 5 were dominated by child-related factors such as letter knowledge, a history of speech impairment and expressive language along with maternal word reading ability. Based on the strength of the predictive factors identified at both age 4 and 5, our results provide initial support for using a targeted model for screening pre-schoolers at risk of not mastering spelling in a timely manner. 相似文献
68.
Tom Harrison 《Ethics and Information Technology》2015,17(4):275-283
This article draws on a study investigating how 11–14 year olds growing up in England understand cyber-bullying as a moral concern. Three prominent moral theories: deontology, utilitarianism and virtue ethics, informed the development of a semi-structured interview schedule which enabled young people, in their own words, to describe their experiences of online and offline bullying. Sixty 11–14 year olds from six schools across England were involved with the research. Themes emerging from the interviews included anonymity; the absence of rules, monitoring and guidance and, the challenges associated with determining the consequences of online actions. The findings demonstrate the advantages of adopting a character-based moral theory to compliment rules and/or consequence based moral theories as the basis for future research into cyber-bullying. The findings evoke some wider implications for future research into cyber-bullying that might equally be applied to investigations into other Internet related moral concerns. 相似文献
69.
This research reports an improved conjugation process for immobilization of antibodies on carboxyl ended self-assembled monolayers (SAMs). The kinetics of antibody/SAM binding in microfluidic heterogeneous immunoassays has been studied through numerical simulation and experiments. Through numerical simulations, the mass transport of reacting species, namely, antibodies and crosslinking reagent, is related to the available surface concentration of carboxyl ended SAMs in a microchannel. In the bulk flow, the mass transport equation (diffusion and convection) is coupled to the surface reaction between the antibodies and SAM. The model developed is employed to study the effect of the flow rate, conjugating reagents concentration, and height of the microchannel. Dimensionless groups, such as the Damköhler number, are used to compare the reaction and fluidic phenomena present and justify the kinetic trends observed. Based on the model predictions, the conventional conjugation protocol is modified to increase the yield of conjugation reaction. A quartz crystal microbalance device is implemented to examine the resulting surface density of antibodies. As a result, an increase in surface density from 321 ng/cm2, in the conventional protocol, to 617 ng/cm2 in the modified protocol is observed, which is quite promising for (bio-) sensing applications.Microfluidics have been implemented in various bio-medical diagnostic applications, such as immunosensors and molecular diagnostic devices.1 In the last decade, a vast number of biochemical species has been detected by microfluidic-based immunosensors. Immunosensors are sensitive transducers which translate the antibody-antigen reaction to physical signals. The detection in an immunosensor is performed through immobilization of an antibody that is specific to the analyte of interest.2 The antibody is often bound to the transducing surface of the sensor covered by self-assembled monolayers (SAMs). SAMs are organic materials that form a thin, packed and robust interface on the surface of noble metals like that of gold, suitable for biosensing applications.3 Thiolic SAMs have a “head” group that shows a high affinity to being chemisorbed onto a substrate, typically gold. The SAMs'' carboxylic functional group of the “tail” end can be linked to an amine terminal of an antibody to form a SAM/antibody conjugation.3,4 The conjugation process is usually accomplished in the presence of carbodiimides, such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). A yield increasing additive, N-Hydroxysuccinimide (NHS), is often used to enhance the surface loading density of the antibody.4,5A typical reaction for coupling the carboxylic acid groups of SAMs with the amine residue of antibodies in the presence of EDC/NHS is depicted in Figure Figure11.4 NHS promotes the generation of an active NHS ester (k2 reaction path). The NHS ester is capable of efficient acylation of amines, including antibodies (k3 reaction path). As a result, the amide bond formation reaction, which typically does not progress efficiently, can be enhanced using NHS as a catalyst.4Open in a separate windowFIG. 1.NHS catalyzed conjugation of antibodies to carboxylic-acid ended SAMs through EDC mediation (Adapted from G. T. Hermanson, Bioconjugate Techniques, 2nd. Edition. Copyright 2008 by Elsevier4). EDC reacts with the carboxylic acid and forms o-acylisourea, a highly reactive chemical that reacts with NHS and forms an NHS ester, which quickly reacts with an amine (i.e., antibody) to form an amide.A number of groups have studied EDC/NHS mediated conjugation reactions such as the ones depicted in Figure Figure1.1. The general stoichiometry of the reaction involves a carboxylic acid (SAM), an amine (antibody), and EDC to produce the final amide (antibody conjugated SAM) and urea. However, the recommended concentration ratio of the crosslinking reagents inside the buffer, i.e., the ratio of EDC and NHS with respect to adsorbates and each other, varies from one study to another.6 The kinetics of the reactions outlined in Figure Figure11 have also been investigated,4,6–8 but only in the absence of NHS for EDC or carboxylic acids in aqueous solutions.8 A relatively recent experimental study verified the catalytic role of the yield-increasing reagent N-hydroxybenzotriazole (HOBt), which acts similarly to NHS.7 In this study, the amide formation rate (k3 reaction path, Figure Figure1)1) was found to be dependent on the concentration of the carboxylic acid and EDC in the buffer solution, and independent of the amine and catalyst reagent concentration. The same group also showed that the amide bond formation kinetics is controlled by the reaction between the carboxylic acid and the EDC to give the O-acylisourea, which they marked as the rate-determining step (k1 reaction path, Figure Figure11).The k1 reaction path, or the conjugation reaction, is usually a lengthy process and takes between 1 and 3 h.4,9 Compared to k1, the k2 and ?k3 reactions are considerably faster. Microfluidics has the potential to enhance the kinetics of these reactions using the flow-through mode.10,11 This improvement occurs because while conventional methods rely only on diffusion as the primary reagent transport mode, microfluidics adds convection to better replenish the reagents to the reaction surfaces. However, there are many fundamental fluidic and geometrical parameters that might affect the process time and reagents consumption in a microfluidics environment, such as concentration of antibodies and reagents, flow rate, channel height, and final surface density of antibodies. A model that studies the kinetics of conjugation reaction against all these parameters would therefore be helpful for the optimization of this enhanced kinetics.There are a number of reports on numerical examination of the kinetics of binding reactions in microfluidic immunoassays.12–15 All these models developed so far couple the transport of reagents, by diffusion and convection, to the binding on the reaction surface. Myszka''s model assumes a spatially homogeneous constant concentration of reagents throughout the reaction chamber, thus fails to describe highly transport-limited conditions due to the presence of spatial heterogeneity and depletion of the bulk fluid from reagents.16,17 In transport-limited conditions, the strength of reaction is superior to the rate of transport of reagents to the reaction surface.18,19 More recently, the convection effects were included in a number of studies, describing the whole kinetic spectrum from reaction-limited conditions to transport-limited reactions.20–22 Immunoreaction kinetics has also been examined with a variety of fluid driving forces, from capillary-driven flows,20 to electrokinetic flows in micro-reaction patches,21 pressure-driven flows in a variety of geometric designs.22 Despite these comprehensive numerical investigations, the fundamental interrelations between the constitutive kinetic parameters, such as concentration, flow velocity, microchannel height, and antibody loading density, have not been studied in detail. In addition, the conjugation kinetics has not yet been exclusively examined.In this paper, a previous model for immunoreaction is modified to study the antibody/SAM conjugation reaction in a microfluidic system. Model findings are used to examine the process times recommended in the literature and possible modification scenarios are proposed. The new model connects the convective and diffusive transport of reagents in the bulk fluid to their surface reaction. The conjugation reaction is studied against fluidic and geometrical parameters such as flow rate, concentration, microchannel height and surface density of antibodies. Damköhler number is used to compare the reaction and fluidic phenomena present and justify the kinetic trends observed. Model predictions are discussed and the main finding on possible overexposure of carboxylates to crosslinking reagents, in conventional protocols, is verified by comparing the resultant antibody loading densities obtained using a quartz crystal microbalance (QCM) set up. The results demonstrate an improved receptor (antibody) loading density which is quite promising for a number of (bio-) sensing applications.23,24 Major application areas include antibody-based sensors for on-site, rapid, and sensitive analysis of pathogens such as Bacillus anthracis,23
Escherichia coli, and Listeria monocytogenes, and toxins such as fungal pathogens, viruses, mycotoxins, marine toxins, and parasites.24 相似文献
70.
Robin Patric Clair Nadia E. Brown Debbie S. Dougherty Hannah K. Delemeester Patricia Geist-Martin William I. Gorden 《Journal of Applied Communication Research》2019,47(2):111-129
#MeToo has breathed new life into the women’s movement and especially into understanding and rectifying sexual harassment, abuse and assault. It has galvanized activists around the globe. And it has placed thousands of stories of the harassed in full view of the public. Sexual harassment, abuse and assault may occur within the organizational context or beyond; but sexual harassment, in particular has been legally labeled an organizational phenomenon. With this in mind, Robin Clair frames the early part of this article around the most recent organizational communication theories (see the appendix for an overview of these theories). Following the essay is a forum, in which invited scholars address questions related to the #MeToo movement. 相似文献