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81.
The Literature of Bibliometrics,Scientometrics, and Informetrics   总被引:4,自引:0,他引:4  
Since Vassily V. Nalimov coined the term ‘scientometrics’ in the 1960s, this term has grown in popularity and is used to describe the study of science: growth, structure, interrelationships and productivity. Scientometrics is related to and has overlapping interests with bibliometrics and informetrics. The terms bibliometrics, scientometrics, and informetrics refer to component fields related to the study of the dynamics of disciplines as reflected in the production of their literature. Areas of study range from charting changes in the output of a scholarly field through time and across countries, to the library collection problem of maintaining control of the output, and to the low publication productivity of most researchers. These terms are used to describe similar and overlapping methodologies. The origins and historical survey of the development of each of these terms are presented. Profiles of the usage of each of these terms over time are presented, using an appropriate subject category of databases on the DIALOG information service. Various definitions of each of the terms are provided from an examination of the literature. The size of the overall literature of these fields is determined and the growth and stabilisation of both the dissertation and non-dissertation literature are shown. A listing of the top journals in the three fields are given, as well as a list of the major reviews and bibliographies that have been published over the years. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
82.
Following an introduction on the use of titanium alloys for aeroengine applications, results are presented on the creep feed grinding of a beta titanium alloy Ti-25V-15Cr-2Al-0.2C?wt.% (BuRTi) using vitrified bonded superabrasive wheels in a fractional factorial experimental design. Despite a general perception to the contrary, the range of titanium alloys in use is wide encompassing different alpha/near alpha, alpha/beta and beta designations, each with specific mechanical/physical properties. In terms of aeroengine use, there are seven or eight key alloys (or their equivalent) used globally with the trend for higher operating capability both in relation to temperature and stress level. In the experimental work, grinding forces were significantly lower with diamond; however, wheels employing CBN grits achieved the highest G-ratio (up to ~280) and lowest surface roughness (~0.73???m of Ra). This was accompanied by workpiece smearing and surface burn, which was evident in the majority of tests using CBN. Additionally, workpiece softening was observed within the first 15???m from the machined surface.  相似文献   
83.
Studies were conducted with columns containing soil and emplaced trichloroethene (TCE) to investigate the potential for TCE source zone remediation with chemical oxidation followed by biologically mediated reductive dehalogenation. Following permanganate flushing of four columns, which resulted in rapid but incomplete removal of TCE DNAPL, no biological activity was observed following the addition of distilled water amended with ethanol and acetate, including two of the four columns that were bioaugmented with a TCE-dechlorinating microbial culture. Flushing with unsterilized site groundwater led to consumption of acetate and ethanol, accompanied by manganese reduction and methanogenesis. Reductive dechlorination of TCE to cis-1,2-dichloroethene (cis-DCE) followed the onset of ethanol and acetate biodegradation in bioaugmented columns only. Partial dechlorination of TCEto ethene was observed only in one of the bioaugmented columns after it was inoculated for a third time. At the end of the study (290 days), a trace amount of cis-DCE was observed in one of the two columns which was not bioaugmented. Reduced conditions created by biostimulation were also conducive to reduction of Mn(IV) from MnO2 in both bioaugmented and nonbioaugmented columns resulting in an increased dissolved manganese (Mn2+) concentration in groundwater.  相似文献   
84.
The T-cell receptor (Tcr) provides specificity for antigen recognition by its variable domain, primarily consisting of two germline encoded variable (V) region gene segments. Thus it has been suggested that inherited polymorphisms in the TCRV gene segments could contribute to differential immune responsiveness (e.g., autoimmunity) in human populations. In the present study, we have sought potentially functional polymorphisms in the germline TCRAV gene segments. Using denaturing gradient gel electrophoresis on polymerase chain reaction (PCR)-amplified products from the pooled DNA of many individuals, we identified polymorphisms in the TCRAV2S1, AV4S1, AV7S1, and AV8S1 gene segments. A complete DNA sequence analysis of these PCR products identified polymorphisms that affected amino acids in the predicted antigen-binding regions of the Tcr alpha chain, as well as polymorphisms in the introns. Genotype analysis of all nine DNA point mutations showed a 5%-50% range (averaging 35%) of minor allele frequencies, often resulting in individuals homozygous for the alternate allele forms. All possible haplotype combinations of the amino acid-affecting polymorphisms were found, indicating that in human populations there are a large number of different germline haplotypes encoding V gene segment alleles. These TCRAV coding region polymorphisms provide the rationale for, and allow the direct testing of, hypotheses concerning inherited polymorphisms within the T-cell receptor genes that may contribute to autoimmune susceptibility.  相似文献   
85.
Men (N?=?526) who patronized gay bars in three cities completed measures of sexual behavior covering the previous 3 months and psychological measures theoretically pertinent to AIDS risk. Thirty-seven percent of the sample reported engaging in unprotected anal intercourse, the behavior most strongly associated with transmission of human immunodeficiency virus (HIV) infection. Perceived peer norms concerning the acceptability of safer sex practices, AIDS health locus of control scores, risk behavior knowledge, age, and accuracy of personal risk estimation, but not personal HIV serostatus knowledge, were associated with high-risk and precaution-taking behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
86.
The ParaScope parallel programming environment   总被引:1,自引:0,他引:1  
The ParaScope parallel programming environment, developed to support scientific programming of shared-memory multiprocessors, is described. It includes a collection of tools that use global program analysis to help users develop and debug parallel programs. The focus is on ParaScope's compilation system. The compilation system extends the traditional single-procedure compiler by providing a mechanism for managing the compilation of complete programs. The ParaScope editor brings both compiler analysis and user expertise to bear on program parallelization. The debugging system detects and reports timing-dependent errors, called data races, in execution of parallel programs. A project aimed at extending ParaScope to support programming in FORTRAN D, a machine-independent parallel programming language for use with both distributed-memory and shared-memory parallel computers, is described  相似文献   
87.
The first part of this article, based on a comparative analysis of recent policies on dangerous dogs among a set of Western European states, shows that small‐scale events – like one dog‐bite – can produce circumstances that confront policy‐makers with a type of ‘forced choice‘, given a particular set of political conditions. The second part, based on a more in‐depth comparison of German and UK approaches, probes beyond the ‘Pavlovian’ level of political response to dog‐bite crises to explore how institutions mediate responses to ‘forced choices’. Dog‐bite crises may temporarily remove normal blockages and constraints on policy development, but this article shows how institutions can still shape policy responses in at least three different ways.  相似文献   
88.
A frontal solution program is presented which may be used for the solution of unsymmetric matrix equations arising in certain applications of the finite element method to boundary value problems. Based on the Gaussian elimination algorithm, it has advantages over band matrix methods in that core requirements and computation times may be considerably reduced; furthermore numbering of the finite element mesh may be completed in an arbitrary manner. The program is written in FORTRAN and a glossary of terms is provided.  相似文献   
89.
The mechanical and metabolic effects of 3 min of complete global ischemia and 25 min of reperfusion were studied in the isolated rat heart. The decrease in contracile function was biphasic; a rapid 50% decline occurred in the first 10 s of ischemia, after which contractile function transiently stabilized and then fell at a slower rate. During reperfusion, recovery of relaxation was impaired relative to recovery of contractile function. A second period of ischemia and reflow produced changes in contractility, relaxation, and lactate production virtually identical to the initial one. In the absence of glycolytic blockade, tissue lactate accumulation developed, no contracture occurred, the pacing threshold did not increase, and reperfusion after 3 min of ischemia resulted in complete recovery of contractile function. Glycolytic blockade with 0.1 mM iodoacetate (IAA) prevented ischemic lactate production, accelerated the fall in contractility, caused irreversible contracture after 30 s of ischemia, an irreversible increase in pacing threshold within 3 min of ischemia, and poor recovery of contractile function with reperfusion. Thus during the first 3 min of severe ischemia, glycolysis exerted a net beneficial effect on myocardial function despite significant tissue lactate accumulation.  相似文献   
90.
The objective of this study was to identify oxidation products of conjugated linoleic acid (CLA), a series of octadecadienoic acids with conjugated double bonds, which have been reported to have antioxidant and anticarcinogenic properties. Reference materials of CLA were oxidized in different concentrations of water/methanol; for example, 0.5 g octadecadienoic acid was dissolved in 50 mL methanol, and 100 mL water was added; this suspension was heated at 50°C and continuously aerated. Aliquots of 5 mL were taken over time, extracted with ether, treated with diazomethane and examined by gas chromatography/mass spectrometry and/or gas chromatography with flame-ionization detection. Products identified included the following furan fatty acids (FFAs): 8,11-epoxy-8,10-octadecadienoic; 9,12-epoxy-9,11-octadecadienoic; 10,13-epoxy-10,12-octadecadienoic; and 11,14-epoxy-11,13-octadecadienoic. Conjugated dienes should be considered as a possible source of FFAs, and CLA may have products common to furans in their overall oxidative scheme.  相似文献   
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