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排序方式: 共有408条查询结果,搜索用时 0 毫秒
81.
Lofts S Chapan PM Dwyer R McLaughlin MJ Choeters I Sheppard SC Adams WJ Alloway BJ Antunes PM Campbell PG Davies B Degryse F De Vries W Farley K Garrett RG Green A Jan Groenenberg B Hale B Harrass M Hendershot WH Keller A Lanno R Liang T Liu WX Ma Y Menzie C Moolenaar SW Piatkiewicz W Reimann C Rieuwerts JS Santore RC Sauvé S Schuetze G Schlekat C Skeaff J Smolders E Tao S Wilkins J Zhao FJ 《Environmental science & technology》2007,41(18):6326-6331
82.
Poly(vinyl acetate-co-butyl acrylate) latexes having oligomeric N-methylol acrylamide were prepared by semi-continuous emulsion polymerization. The effects of new protective colloid and comonomer
ratios on the physicochemical and colloidal properties of latexes were investigated. The changes in homopolymer and copolymer
latexes were determined by measuring viscosity, particle size, molecular weight (MW), molecular weight distribution (MWD),
and surface tension. [`(M)]n \bar{M}_{n} values of copolymer latexes were found to be lower than the MWs of the poly(vinyl acetate) and poly(butyl acrylate) homopolymers.
In general, [`(M)]n \bar{M}_{n} and
[`(M)]\textw \bar{M}_{\text{w}} values of copolymer latexes changed irregularly with increasing BuA ratio in the copolymer composition. 相似文献
83.
Internet use and depression among older adults 总被引:2,自引:0,他引:2
The findings regarding the impact of Internet use on well-being are mixed and studies are often criticized due to small samples and lack of consistency in measurement. Fewer studies have examined this issue among older adults. The purpose of this study is to examine the relationship between Internet use and depression among retired Americans age 50 years or older. Using data from the Health and Retirement Survey, the study estimates the relationship between Internet use and depression through combined use of regression and propensity score methodologies. All empirical methods indicate a positive contribution of Internet use to mental well-being of retired older adults (?50 years), reducing depression categorization by approximately 20–28%. 相似文献
84.
Abramowitz Jonathan S.; Deacon Brett J.; Olatunji Bunmi O.; Wheaton Michael G.; Berman Noah C.; Losardo Diane; Timpano Kiara R.; McGrath Patrick B.; Riemann Bradley C.; Adams Thomas; Bj?rgvinsson Thr?stur; Storch Eric A.; Hale Lisa R. 《Canadian Metallurgical Quarterly》2010,22(1):180
Although several measures of obsessive-compulsive (OC) symptoms exist, most are limited in that they are not consistent with the most recent empirical findings on the nature and dimensional structure of obsessions and compulsions. In the present research, the authors developed and evaluated a measure called the Dimensional Obsessive-Compulsive Scale (DOCS) to address limitations of existing OC symptom measures. The DOCS is a 20-item measure that assesses the four dimensions of OC symptoms most reliably replicated in previous structural research. Factorial validity of the DOCS was supported by exploratory and confirmatory factor analyses of 3 samples, including individuals with OC disorder, those with other anxiety disorders, and nonclinical individuals. Scores on the DOCS displayed good performance on indices of reliability and validity, as well as sensitivity to treatment and diagnostic sensitivity, and hold promise as a measure of OC symptoms in clinical and research settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
Hale Sutcu 《Korean Journal of Chemical Engineering》2007,24(5):736-741
Pyrolysis of peat obtained from Yeniça?a, Bolu, Turkey was conducted in a fixed-bed tube furnace under various conditions, and variations in the structure of the char, tar and gas products were examined. The chars produced were studied by proximate and ultimate analyses. The maximum tar yield of 20.41% was obtained at a heating rate of 20 °C/min, a temperature of 450 °C, a sweeping gas flow rate of 100 ml/min and a 0.5–2.0 mm size range. The chemical composition of the tar was examined by elemental analysis, FTIR spectroscopy, 1H-NMR spectroscopy and column chromatography. The chemical composition of the tar with dense aliphatic structure was established to be CH1.22O0.25N0.02. The composition of the gases obtained at a heating rate of 20 °C/min for the 0.5–2.0 mm size range was examined by gas chromatography. 相似文献
86.
Alex Gansen Martin Řehoř Clemens Sill Patrycja Polińska Stephan Westermann Jean Dheur Jack S. Hale Jörg Baller 《应用聚合物科学杂志》2020,137(24):48806
An optical method allowing the characterization of melt flow instabilities typically occurring during an extrusion process of polymers and polymer compounds is presented. It is based on a camera-acquired image of the extruded compound with a reference length scale. Application of image processing and transformation of the calibrated image to the frequency domain yields the magnitude spectrum of the instability. The effectiveness of the before mentioned approach is shown on Styrene-butadiene rubber (SBR) compounds, covering a wide range of silica filler content, extruded through a Göttfert capillary rheometer. The results of the image-based analysis are compared with the results from the sharkskin option, a series of highly sensitive pressure transducers installed inside the rheometer. A simplified version of the code used to produce the optical analysis results is included as supplementary material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48806. 相似文献
87.
Membranes are located in a membrane module that physically seals and isolates the feed stream from the permeate flux in membrane bioreactors (MBRs). Therefore, module type, structure, and geometrical configuration are critical design considerations affecting membrane performance in MBRs. In this study, impact of membrane module design on treatment and filtration performance of MBRs was investigated. For this purpose, two flat sheet membrane modules with different outlet structures and module geometries, including rectangular- and D-shaped, were tested. In addition to the differences in outlet structure and module geometry, size of circular structures which supported membranes in rectangular- and D-shaped modules differed from each other. Considering the results, permeate quality was not affected from the change in the module design. However, the most remarkable impact of the module design was observed on the transmembrane pressure (TMP) evolution and fouling potential. D-shaped membrane module including smaller circular structures resulted in a decrease in fouling potential and thus, this module could be operated longer time in comparison to rectangular-shaped membrane module without a severe TMP increase. The observed differences in TMP increase and fouling potential lead to the hypothesis that module design is a critical factor affecting filtration performance in MBRs. 相似文献
88.
This study presents the use of original systems based on Candida antarctica lipase B (CALB) immobilized on montmorillonite and sepiolite nanoclays as efficient catalysts for the enzymatic polymerization of ε-caprolactone (ε-CL) and the in situ elaboration of nanohybrids. 相似文献
89.
While thermally supported cats experienced a drop in body temperature during dental procedures, the drop was significantly greater in cats without thermal support. As cats are at risk of developing clinical hypothermia during dental procedures, steps should be taken to minimize the loss of body heat. 相似文献
90.
HL Hale JE Husband K Gossios AR Norman D Cunningham 《Canadian Metallurgical Quarterly》1998,53(10):735-741
PURPOSE: To assess the incidence, characteristics and prognostic significance of calcification within colorectal hepatic metastases. MATERIALS AND METHODS: A retrospective analysis of CT in 265 patients with locally advanced or metastatic cancer was performed. Four groups were defined: (a) calcification within liver metastases prior to therapy, (b) noncalcified liver metastases with development of calcification on therapy, (c) noncalcified liver metastases, and (d) advanced local tumour without liver metastases. The number of calcified deposits in each patient was documented. A marker lesion was analysed for character, distribution and percentage of calcification. Survival between the four groups was compared. RESULTS: Twenty-nine (11%) patients had calcified liver metastases at presentation and 10 (4%) developed calcification during chemotherapy. Analysis of a marker lesion showed that the most frequent characteristic was fine calcification with a variable distribution. The most frequent change on treatment was alteration in the extent of calcification. Calcification developing on treatment was usually central. There was no difference in survival between groups 1, 2 and 3, but groups 1, 2 and 3 had a shorter survival than group 4. CONCLUSION: Calcification of liver metastases shows a variable pattern and may develop or change during therapy. Liver metastatic calcification may not carry any prognostic significance in colorectal cancer. 相似文献