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排序方式: 共有324条查询结果,搜索用时 93 毫秒
1.
J Pa?yga 《Canadian Metallurgical Quarterly》1998,36(3-4):79-92
Three polymorphic subtypes of erythrocyte histone H1 (H1.a, H1.b, and H1.z) were analyzed using a sodium dodecyl sulfate polyacrylamide gel in quail populations divergently selected for a high (line 1) or low (line 2) reduction in body mass following temporary food withdrawal. Both H1.b and H1.z histone alleles were found to be differently distributed in these populations during the selection period. The frequency of b1 in line 2 was approximately 1.9-2.8 times lower than in line 1 and approached the values in line 1 when the selection was suspended. Similarly, the frequency of allele z2 at locus H1.z increased significantly (about 1.6-2.3 times) in line 2 during selection and returned to the initial values when selection was stopped. On the other hand, allele a0 at locus H1.a was kept at relatively low levels (usually below 0.05) in both lines during selection. At that time its level was approximately three to four times lower than in a random mating control population. When selection was suspended, the frequency of a0 in line 1 increased significantly, approaching the values in the control line, and remained essentially unchanged in line 2. Thus, all three polymorphic histone H1 loci in quail responded through changes in allele frequencies to the breeding selection, which was directed at the amount of body weight loss upon transient starvation. It seems that either H1 histone locus could be linked to loci controlling the rate of body weight reduction following starvation or weight loss during fasting might be influenced by a panel of H1 histone alleles that can contribute to functional differences in avian chromatin. 相似文献
2.
Thick film technology was used to manufacture a solid-state electrochemical nitrogen dioxide sensor. The prepared sensor
has a linear dependence of electromotive force that is based in the NO2 concentration level. This paper presents discussion on a thick-film sensor that has a much smaller dimension and shorter
response time as compared to typical ceramic solid-state electrochemical devices.
Received: 26 February 1996/Accepted: 27 June 1996 相似文献
3.
In metastatic breast cancer the goal to reach must be the best possible palliation with minimum discomfort for the patient. We reviewed our experience with radiotherapy (20 or 30 Gy), systemic therapy and brace. Among 2200 breast cancer patients, we extracted 28 potential candidates for resection. All of them developed new metastases outside the treated field within one year. Local control was achieved in 68%, and 80% of them had stable or better performance status at 3 months. From our analysis, even patients with a so called "solitary lesion" do not seem to have a better prognosis than others. We conclude that radiotherapy (with systemic therapy and a brace) is still first-choice treatment for vertebral metastases; CT-guided percutaneous biopsy can avoid worthless major operations. The role of surgery should be limited to neurological compression, severe mechanical instability and to salvage the failures of conservative treatment. 相似文献
4.
A non-intrusive estimation for high-quality Internet TV services 总被引:1,自引:0,他引:1
Alberto?Fraga Laura?Pozueco Xabiel?Garcia Pa?edaEmail author Roberto?García David?Melendi Sergio?Cabrero 《Multimedia Tools and Applications》2011,54(3):569-588
This paper presents a non-intrusive estimator for Internet TV services based on streaming technology. Analyzing the video
packets received by the client application, the estimator is capable of selecting the most suitable encoding bitrate for the
available bandwidth in the end-to-end path. The estimator has been integrated in a real client/server architecture and evaluated
with different network traffic situations. The results of the performed evaluation have revealed the stability and adaptation
speed as the best qualities of our proposal. 相似文献
5.
M. Pa?ciak A. P. Heerdegen D. J. Goossens R. E. Whitfield A. Pietraszko T. R. Welberry 《Metallurgical and Materials Transactions A》2013,44(1):87-93
We use an extensive X-ray diffuse scattering dataset collected from the relaxor ferroelectric PbZn1/3Nb2/3O3 to study the feasibility of refining a nanoscale structure with the reverse Monte Carlo method. Six integer and non-integer reciprocal sections are used with a total number of nearly 105 symmetry-independent data points. Very good agreement between observed and calculated diffuse scattering patterns is achieved with rather subtle diffuse intensity modulations being satisfactorily reproduced. The correlations within the refined local structure are related to the possible physical mechanisms behind them. We discuss the ambiguity of the obtained results and feasible constraining schemes. 相似文献
6.
7.
Sergiu Cecoltan Izabela-Cristina Stancu Diana Maria Drăguşin Andrada Serafim Adriana Lungu Cătălin Ţucureanu Iuliana Caraş Vlad Constantin Tofan Aurora Sălăgeanu Eugeniu Vasile Romain Mallet Daniel Chappard Cristin Coman Mircea Istodorescu Horia Iovu 《Journal of materials science. Materials in medicine》2017,28(10):153
8.
9.
Sergiu Coseri Alina Spatareanu Liviu Sacarescu Vlad Socoliuc Ioan Sorin Stratulat Valeria Harabagiu 《应用聚合物科学杂志》2016,133(5)
Ultrasmall superparamagnetic iron oxide (Fe3O4) nanoparticles coated by biocompatible pullulan (Pu‐USPIO) with sizes below 10 nm and having a magnetite core and a hydrophilic outer shell of pullulan were prepared. The formed Pu‐USPIOs were thoroughly characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, and small‐angle X‐ray scattering experiments. The content of magnetic nanoparticles embedded into the pullulan matrix was determined by thermogravimetric analysis. Vibrating sample magnetometry analysis was used to evaluate the magnetic properties of the Pu‐USPIO samples. Because of the presence of pullulan, these nanoparticles could be conditioned in many versatile forms, from a clear solution to magnetic films, for potential applications, including magnetic hyperthermia mediators. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42926. 相似文献
10.
Roland Mainz Alfons Weber Humberto Rodriguez‐Alvarez Sergiu Levcenko Manuela Klaus Paul Pistor Reiner Klenk Hans‐Werner Schock 《Progress in Photovoltaics: Research and Applications》2015,23(9):1131-1143
Ga segregation at the backside of Cu(In,Ga)Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu–In–Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real‐time synchrotron‐based X‐ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross‐sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In–Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu–In–Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In–Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga‐rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 min reached conversion efficiencies of up to 14.2 % (total area, without anti‐reflective coating). The evolution of the Cu(In,Ga)Se2 diffraction signals reveals that the minimum process time for high‐quality Cu(In,Ga)Se2 absorbers is limited by cation ordering rather than Se incorporation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献