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排序方式: 共有196条查询结果,搜索用时 31 毫秒
51.
52.
ABSTRACT: Amylase, with MW of 59 kDa, was purified from small abalone Haliotis sieboldii by ammonium sulfate fractionation, CM Sepharose Fast Flow and Sephacryl S-100 HR chromatographies. The optimal pH and temperature of purified amylase were 6.0 and 37°C, respectively. The purified enzyme was stable at pH 6.0–8.0 and low temperatures. It was activated by Ba2+ , Mg2+ , Ca2+ , Co2+ , Ni2+ , Mn2+ , K+ , Ag+ , Na+ and Li+ , but completely or partially inhibited by Al3+ , Cu2+ , Cd2+ , Hg2+ and Zn2+ . EDTA could completely inhibit, while iodoacetamide, N-ethylmaleimide and urea partially inhibit the purified amylase. According to the digestion mode of various polysaccharides, the purified enzyme was considered to be an α-amylase. 相似文献
53.
Kato Sumie Koike Takayoshi Lei Thomas T. Hsieh Chang-Fu Ueda Kunihiko Mikami Tetsuo 《New Forests》2000,19(1):109-114
Mitochondrial DNA restriction fragment length polymorphisms were used to examine cytoplasmic diversity within a relic-like population of Fagus hayatae, located in northern Taiwan. Fifteen trees were surveyed for three restriction endonucleases (BamHI, EcoRI and HindIII) and five mitochondrial gene probes (atpA, atp6, atp9, coxI and coxII). The analysis failed to reveal any polymorphisms, an observation that suggests cytoplasmic uniformity in the F. hayatae population examined. It is also interesting to note that the chondriome type of our F. hayatae samples is very close to that characteristic of F. crenata populations in the southernmost area of Japan. 相似文献
54.
Aruna Panda Ivan Tatarov Billie Jo Masek Justin Hardick Annabelle Crusan Teresa Wakefield Karen Carroll Samuel Yang Yu-Hsiang Hsieh Michael M. Lipsky Charles G. McLeod Myron M. Levine Richard E. Rothman Charlotte A. Gaydos Louis J. DeTolla 《Comparative immunology, microbiology and infectious diseases》2014
Bacteremia is an important cause of morbidity and mortality in humans. In this study, we focused on the development of an animal model of bacteremia induced by non-typhoidal Salmonella. New Zealand White rabbits were inoculated with a human isolate of non-typhoidal Salmonella strain CVD J73 via the intra-peritoneal route. Blood samples were collected at specific time points and at euthanasia from infected rabbits. Additionally, tissue samples from the heart, lungs, spleen, gastrointestinal tract, liver and kidneys were obtained at euthanasia. All experimentally infected rabbits displayed clinical signs of disease (fever, dehydration, weight loss and lethargy). Tissues collected at necropsy from the animals exhibited histopathological changes indicative of bacteremia. Non-typhoidal Salmonella bacteria were detected in the blood and tissue samples of infected rabbits by microbiological culture and real-time PCR assays. The development of this animal model of bacteremia could prove to be a useful tool for studying how non-typhoidal Salmonella infections disseminate and spread in humans. 相似文献
55.
Left-handed DNA in vivo 总被引:35,自引:0,他引:35
A Jaworski W T Hsieh J A Blaho J E Larson R D Wells 《Science (New York, N.Y.)》1987,238(4828):773-777
Left-handed DNA is shown to exist and elicit a biological response in Escherichia coli. A plasmid encoding the gene for a temperature-sensitive Eco RI methylase (MEco RI) was cotransformed with different plasmids containing inserts that had varying capacities to form left-handed helices or cruciforms with a target Eco RI site in the center or at the ends of the inserts. Inhibition of methylation in vivo was found for the stable inserts with the longest left-handed (presumably Z) helices. In vitro methylation with the purified MEco RI agreed with the results in vivo. Supercoil-induced changes in the structure of the primary helix in vitro provided confirmation that left-handed helices were responsible for this behavior. The presence in vivo of left-handed inserts elicits specific deletions and plasmid incompatibilities in certain instances. 相似文献
56.
High-speed, gross, alpha autoradiographs can be made if silver-activated zinc sulfide is used as an intensifier in conjunction with high-speed film. The intensifier is interposed between the sample and film. This technique requires about 1/1000 of the exposure time required with Kodak NTB plates. The gross autoradiographs have greater contrast but slightly less resolution than conventional plates. 相似文献
57.
Krimigis SM Mitchell DG Hamilton DC Krupp N Livi S Roelof EC Dandouras J Armstrong TP Mauk BH Paranicas C Brandt PC Bolton S Cheng AF Choo T Gloeckler G Hayes J Hsieh KC Ip WH Jaskulek S Keath EP Kirsch E Kusterer M Lagg A Lanzerotti LJ Lavallee D Manweiler J McEntire RW Rasmuss W Saur J Turner FS Williams DJ Woch J 《Science (New York, N.Y.)》2005,307(5713):1270-1273
The Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft observed the saturnian magnetosphere from January 2004 until Saturn orbit insertion (SOI) on 1 July 2004. The MIMI sensors observed frequent energetic particle activity in interplanetary space for several months before SOI. When the imaging sensor was switched to its energetic neutral atom (ENA) operating mode on 20 February 2004, at approximately 10(3) times Saturn's radius RS (0.43 astronomical units), a weak but persistent signal was observed from the magnetosphere. About 10 days before SOI, the magnetosphere exhibited a day-night asymmetry that varied with an approximately 11-hour periodicity. Once Cassini entered the magnetosphere, in situ measurements showed high concentrations of H+, H2+, O+, OH+, and H2O+ and low concentrations of N+. The radial dependence of ion intensity profiles implies neutral gas densities sufficient to produce high loss rates of trapped ions from the middle and inner magnetosphere. ENA imaging has revealed a radiation belt that resides inward of the D ring and is probably the result of double charge exchange between the main radiation belt and the upper layers of Saturn's exosphere. 相似文献
58.
59.
Han JH Krochta JM Kurth MJ Hsieh YL 《Journal of agricultural and food chemistry》2000,48(11):5278-5282
The hydroxyl groups of lactitol were propoxylated to produce poly(ether polyol) (LPEP). The average pK(a) value of hydroxyl groups of the polyol was 1.63. Cross-linked hydrogels were synthesized by esterification with chlorinated poly(ethylene glycol) bis(carboxymethyl) ether (PEGBCOCl). The swelling ratio decreased with increasing cross-linking ratio (PEGBCOCl:LPEP) from 2:1 to 4:1 in the hydrogels and was sensitive to temperature change between 25 and 55 degrees C and concentrations of salt and glucose. The swelling ratio did not change significantly with pH in the range of 4-9. The release profiles of a model active agent, acetylsalicylic acid, from the hydrogels showed that the diffusional release rate had a half-order dependence on time, and the diffusivity decreased with increasing cross-linking ratio. This work demonstrated that LPEP-based hydrogels can be used for controlled delivery of drugs and agrochemicals and the release rates can be controlled with the cross-linking ratio of the hydrogel. 相似文献
60.
Ling-Ling Hsieh Chih-Chung Chang Usha Sree Jiunn-Guang Lo 《Water, air, and soil pollution》2006,170(1-4):107-121
This study investigates the composition and concentrations of volatile organic compounds (VOCs) in air-conditioned office space and low-level waste (LLW) repository sites of nuclear power plants located in Taiwan. Air samples were collected in the office space and technical rooms of administration buildings of the three nuclear power plants and in LLW repository site using canisters. Thirty-six toxic organic compounds including aromatics, CFCs and chlorinated hydrocarbons were identified and quantified using gas chromatograph/mass spectrometer (GC/MS). The results indicated that the concentrations of most determined species were similar to that in urban areas; however, the air at the LLW building contained abundant trichlorotrifluoroethane (CFC-113), trichloroethylene, toluene, 1,2,4-trimethylbenzene and CFC-12 in concentrations markedly higher than the background levels. Only toluene and 1,2,4-trimethylbenzene were detected with low concentrations in the air of LLW repository site. In addition, comparison of the ambient air concentration at several major industries and urban atmosphere revealed that the nuclear power plants emitted and/or leaked higher concentration of chlorinated hydrocarbons among them. 相似文献