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A healthy civil society has long been held as vital to a healthy democracy and there is interest in whether the Internet affects this linkage. This paper explores the relationships between offline and online modes of associational life and also analyzes offline and online interactions with local governments in the US context. Based on our empirical analyses of 1,203 respondents, we show that online participation is not simply an extension of offline participation, but can be distinguished in important ways. First, we find that political and community-oriented engagements cluster separately from more private-regarding engagements. Second, participants of online democratic engagement are not characterized by the SES markers associated with offline democratic engagement who are older, have higher incomes, and have lived in the community longer. Finally, we find significant links between democratic engagement with the political system and involvement with political associations (but not social and community-oriented associations).  相似文献   
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Recently, the model of adoption of technology in households (MATH) was developed and tested in the context of household personal computer (PC) adoption. In this study, we apply MATH to predict personal computer (PC) use. We conducted a nationwide survey including 370 households that owned at least one PC. Results indicate that attitudinal beliefs are extremely important in determining use of a PC in the household. In contrast to previous work examining adopters, normative and control beliefs were not significant in predicting use. Furthermore, several determinants of adoption that were important at different stages of the household life cycle were found nonsignificant in predicting use for the same stages of the household life cycle. Overall, the results demonstrate that the belief structure for household PC use is different from that of household PC adoption. Further, the results provide additional evidence regarding the importance of including household life cycle in studies of household technology adoption and use.  相似文献   
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Heavy metals are important toxicants known to exert adverse effects in humans and animals, given sufficient exposure and accumulation in the body. This has a great concern both at personal and public health risk. Heavy metals are also known to interact with the essential trace minerals at the level of absorption and also during the metabolism. The adverse effects of the absorbed and accumulated heavy metals include neurological, reproductive, renal and hematological systems. Children are more sensitive than adults to the effects of lead. Efforts are made to understand the mechanism of the interactions of heavy metals with essential trace minerals at the level of absorption. With available sensitive and specific methodologies like Anodic Stripping Voltammetry for the evaluation of the levels of toxic heavy metals such as lead, cadmium, mercury etc., better understanding of heavy metal absorption is made possible. Due to the poor nutritional standards, risk of heavy metal exposure is still a major concern in developing countries. Studies carried out by the author have provided evidence towards the understanding of the prevailing mechanisms of metal-metal interaction at the intestinal level. During growth and development the demand for the essential minerals being at higher level, differentiation of various essential metals and heavy metals pose an inherent problem due to certain common properties shared by them. With this approach to the problem of heavy metal toxicity, it is preventable not only with environmental intervention but also by the nutritional management.  相似文献   
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Syngnathids (seahorses, pipefishes and seadragons) exhibit an array of morphological innovations including loss of pelvic fins, a toothless tubular mouth and male pregnancy. They comprise two subfamilies: Syngnathinae and Nerophinae. Genomes of three Syngnathinae members have been analyzed previously. In this study, we have sequenced the genome of a Nerophinae member, the Manado pipefish (Microphis manadensis), which has a semi-enclosed brood pouch. Comparative genomic analysis revealed that the molecular evolutionary rate of the four syngnathids is higher than that of other teleosts. The loss of all but one P/Q-rich SCPP gene in the syngnathids suggests a role for the lost genes in dentin and enameloid formation in teleosts. Genome-wide comparison identified a set of 118 genes with parallel identical amino acid substitutions in syngnathids and placental mammals. Association of some of these genes with placental and embryonic development in mammals suggests a role for them in syngnathid pregnancy.  相似文献   
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Output reversibility involves dynamical systems where for every initial condition and the corresponding output there exists another initial condition such that the output generated by this initial condition is a time-reversed image of the original output with the time running forward. Through a series of necessary and sufficient conditions, we characterize output reversibility in linear discrete-time dynamical systems in terms of the geometric symmetry of its eigenvalue set with respect to the unit circle in the complex plane. Furthermore, we establish that output reversibility of a linear continuous-time system implies output reversibility of its discretization. In addition, we present a control framework that allows to alter the system dynamics in such a way that a discrete-time system, otherwise not output reversible, can be made output reversible. Finally, we present numerical examples involving a discretization of a Hamiltonian system that exhibits output reversibility and an example of a controlled system that is rendered output reversible.  相似文献   
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Among the heavy metals, lead still remains the major toxic pollutant of the environment. Human exposure to lead can occur through numerous pathways including air, food, dust, soil, and water. In the present study 14 lead poisoned patients with non-occupational lead exposure were evaluated. They were followed up and compared against the controls with no history of lead exposure. The patients had high blood lead levels and symptoms of weakness, dizziness, abdominal pain, generalized body ache, loss of appetite, and anxiety. Repeated course of chelation therapy helped to bring down their body burden of lead. Alternative sources for lead exposure can cause severe lead poisoning in general population. Screening and medical management of such individuals is very important to identify and eliminate sources of lead. The treatment and management requires a thorough medical evaluation and environmental intervention.  相似文献   
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