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排序方式: 共有159条查询结果,搜索用时 15 毫秒
61.
Pål Anders Wang Birthe Vang Alice Marie Pedersen Iciar Martinez Ragnar Ludvig Olsen 《Food chemistry》2011
Fish muscle is rapidly degraded during post-mortem storage, due to proteolytic enzymes acting probably both on muscle cells and connective tissue. In this work we have developed a model system which may be used to study the enzymatic degradation occurring in intact post-mortem fish muscle. Degradation of myosin heavy chain (MHC) was monitored in muscle with pH adjusted to 6.05, 6.3 and 6.9 and in the presence of the enzyme inhibitors PMSF, EDTA, phenanthroline, pepstatin A, antipain, E-64 and the cysteine proteinase activator dithiothreithol (DTT). After storage, myofibrillar proteins were isolated and MHC-specific antibodies used to study the degradation in the different samples. MHC from muscle with pH 6.05 and 6.3 was degraded, while no severe degradation was observed at pH 6.9. Introduction of enzyme inhibitors into the muscle tissue clearly showed that mainly cysteine and aspartic proteinases are responsible for the in situ MHC degradation. This is supported by the severe breakdown of MHC in the muscle samples containing DTT. 相似文献
62.
Muhammad Imadur Rahman Ragnar Reynisson Daniel Figueiredo Ramjee Prasad 《Wireless Personal Communications》2009,50(1):83-97
This article proposes a novel way of grouping users in an orthogonal frequency division multiplexing (OFDM) communication
link based on predefined criteria. The total available spectrum is divided into a number of bands equal to the number of groups.
For efficient time-frequency resource allocation, sub-carrier and band hopping are used simultaneously. Under some constraints,
sub-carriers can also be assigned to different users based on known channel characteristics using dynamic sub-carrier allocation.
Sub-carrier and band hopping are used for mitigating the frequency selectivity of the wireless channel and for minimizing
and avoiding interference in the system. The proposed scheme is equally applicable to both downlink and uplink.
相似文献
Ramjee PrasadEmail: |
63.
Ragnar Berg 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1925,49(6):378-380
Ohne Zusammenfassung 相似文献
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68.
Oskam IC Lyche JL Krogenaes A Thomassen R Skaare JU Wiger R Dahl E Sweeney T Stien A Ropstad E 《Reproduction (Cambridge, England)》2005,130(5):731-742
In this study, female goats were orally exposed to PCB126 or PCB153, at 49 ng/kg body weight per day and 98 microg/kg body weight per day respectively, from gestational day 60 until delivery at approximately day 150. Exposure of the offspring continued via lactation until postnatal day 40. Reproductive toxicity in the male offspring was studied by the evaluation of conventional reproductive endpoints as well as flow cytometric analyses of spermatogenesis and sperm chromatin structure. PCB153-treated animals showed a significant smaller testis diameter in comparison to the control group. Neither of the treated groups showed differences for plasma FSH in comparison to controls. PCB153-treated animals differed significantly from the control group with respect to plasma LH and testosterone levels, whereas PCB126-treated animals only differed from the controls in plasma testosterone concentrations. Neither the PCB126 nor the PCB153 group differed from the controls with respect to the conventional sperm parameters or testis histology. A significant lower ratio of interstitium area to seminiferous tubules area and proportion of diploid testis cells were observed for the PCB153 group. Sperm from PCB153-treated animals showed a significantly higher percentage of sperm with damaged DNA. From the results of the present study it was concluded that PCB153 was able to induce alterations in reproductive endpoints related to the hypothalamic-pituitary-axis as well as to the testis. The effects observed in male kids after a long-term maternal exposure to PCB153 support the concept that exposure to endocrine-disrupting compounds during foetal development may lead to adverse reproductive effects in adult life. 相似文献
69.
Ragnar Bye 《Journal of Automated Methods and Management in Chemistry》1989,11(4):156-158
The use of hydride generation is often useful in environmental
analysis. The normal acid sodium tetrahydroborate reaction
provides exceptional sensitivity with continuous flow hydride
generators. In some situations there are interferences which will
mask the sensitivity. An alternative chemistry system is described
here and is shown to offer similar sensitivity to that normally used.
A commercial continuous flow analyser is used in this work. 相似文献
70.
Ragnar Larsson 《Catalysis Letters》1996,36(3-4):171-173
A discussion is presented on the relation between true and apparent activation energies found in heterogeneous catalysis. The possibility of a transient species defining the rate determining step is emphasized. In such a case, the difference between apparent and true activation energies can be quite small. Such a condition is of importance for the understanding of phenomena involving the activation energy, such as the isokinetic effect. 相似文献