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排序方式: 共有784条查询结果,搜索用时 15 毫秒
71.
72.
Wireless Indoor Communications Using an Optical Highway 总被引:1,自引:1,他引:0
The wireless indoor communications system employing an optical backboneprovides an economic and flexible approach for local area networks in officebuildings. In this approach the wireless communication serves small picocellsthat are interconnected by optical highways. The performance of the system isenhanced by assigning specific subcarriers for the individual picocells whichenables the transmission of the radio channels without altering theirmodulation format. The reception is simplified by a direct optical-microwavemixing method providing simultaneous optical detection and frequency shifting.This method allows for simple and cost-effective radio nodes. 相似文献
73.
S Gabriel A Kivi A Eilers R Kovács U Heinemann 《Canadian Metallurgical Quarterly》1998,9(11):2583-2587
Immature glia may not be able to buffer K+ ions released during neuronal activity. Therefore, we investigated entorhinal-hippocampal slices of juvenile rats (ages P15-18 and P22-26) using a perfusion medium containing 2 mM BaCl2 in order to block glial inward rectifying and leak potassium channels. In contrast to adult animals, rises in [K+]o in slices from juvenile animals elicited by repetitive alvear stimulation were not augmented by Ba2+. Ba2+ effects on fast field potentials, slow field potentials and the applied current sink source distribution were roughly similar as in adult rats. We conclude that the capacity to buffer large quantities of K+ ions by mechanisms involving Ba2+-sensitive K+ channels has not yet developed in juveniles. 相似文献
74.
Z Zomborszky T Fehér E Horn E Poteczin S Tuboly M Kovács-Zomborszky 《Canadian Metallurgical Quarterly》1996,44(4):433-441
In studies on the adaptation of red deer (Cervus elaphus) to farm conditions, some blood parameters of 3- to 9-year-old captured and farmed hinds were compared. The test variable included blood plasma creatine kinase (CK), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activities, the concentrations of glucose, urea, total protein (TP), serum cortisol, haemoglobin (Hb), and the blastogenic transformation of lymphocytes upon stimulation by the nonspecific mitogens Phaseolus vulgaris (PHA) and Concanavalin A (ConA) in the lymphocyte stimulation test (LST). The effects exerted by probiotic preparation (Ascogen) on the same parameters were studied in farmed deer. In hinds that had been kept under farm conditions for 10 months, CK activity was lower (P < 0.05) and blood urea concentration higher (P < 0.001) than at the time of capture, while their blood glucose concentration exceeded (P < 0.01) that of farmed hinds. Hinds treated with Ascogen had lower ALT activity (P < 0.001) and showed a higher increase in PHA-induced blastogenic transformation of lymphocytes than the control hinds. 相似文献
75.
G Kovács K Dublecz F Husvéth L Wágner D Gerendai J Orbán H Manilla 《Canadian Metallurgical Quarterly》1998,46(2):285-294
The intrinsic fluorescence of homogeneous castor oil seed cytosolic fructose-1,6-bisphosphatase (FBPasec) was used as an indicator of conformational changes due to ligand binding. Binding of the substrate and the inhibitor fructose-2,6-bisphosphate (F-2,6-P2) was quantitatively compared to their respective kinetic effects on enzymatic activity. There are two distinct types of substrate interaction with FBPasec, corresponding to catalytic and inhibitory binding, respectively. Inhibitory substrate binding shares several characteristics with F-2,6-P2 binding which indicates that both ligands bind at the same site. However, F-2,6-P2 does not prevent fluorescence transitions attributed to catalytic substrate binding. The marked synergistic inhibition of FBPasec by AMP and F-2,6-P2 appears to arise via AMP's promotion of F-2,6-P2 binding. Based on the X-ray crystal structure of porcine kidney FBPase our modelling studies suggest the existence of a distinct F-1,6-P2/F-2,6-P2 inhibitory binding site which partially overlaps with the enzyme's catalytic site. We propose that a pronounced allosteric transition mediated by AMP binding increases access of F-1,6-P2 and F-2,6-P2 to this common inhibitory binding site. 相似文献
76.
77.
The development of cross-tolerance to an analgesic effect has been observed between a mu-receptor agonist, heroin, and a delta-receptor agonist, Met2-Pro5-enkephalinamide. Repeated treatments with heroin twice a day for 4 days resulted in a decreased nociceptive effect to enkephalin on day 5. The enkephalin dose-response line was shifted to the right, considered a sign of the development of cross-tolerance. Peripheral treatment with oxytocin blocked the development of heroin-enkephalin cross-tolerance. A similar effect was observed after intracerebroventricular administration of oxytocin, supporting our assumption that oxytocin blocks the development of heroin-enkephalin cross-tolerance via CNS mechanisms. 相似文献
78.
J Stulík J Bures P Jandík F Langr H Kovárová A Macela 《Canadian Metallurgical Quarterly》1997,18(3-4):625-628
Analysis of the expression of hsp70 (70 kDa heat-shock proteins) in normal and pathological tissues might prove their potential diagnostic and prognostic values. In the present study, we combined high-resolution two-dimensional polyacrylamide gel electrophoresis with immunoblotting to study hsp70 expression in normal, preneoplastic and neoplastic colonic mucosa. By monoclonal anti-hsp70 antibody, recognizing both the constitutive and inducible forms of hsp70, we have detected six charge isoforms localized in the pH 5.1-5.3 range and in the molecular mass range of 68-69 kDa in normal colonic mucosa. Immunostaining of hsp70 in polypous and malignant tissues revealed qualitative as well as quantitative changes in the expression of more acidic isoforms of hsp70 in comparison with normal tissue. Furthermore, the different basic isoforms of hsp70 were detected in chronically inflamed colonic mucosa from patients suffering from ulcerative colitis (UC) or Crohn's disease (CD). Besides the standard hsp70 protein pattern, additional proteins with molecular masses of about 39, 40, 74 and 75 kDa were variably immunostained in normal and pathological specimens. These observations suggest that hsp70 expression may be closely linked to disease etiology and/or pathophysiology. 相似文献
79.
Sándor Tömösközi Lilla Gyenge Ágnes Pelcéder János Varga Tibor Abonyi Radomir Lásztity 《European Food Research and Technology》2008,226(6):1343-1348
The gross chemical composition and functional properties (solubility, emulsifying and foaming properties) of different amaranth
protein preparations were studied in model systems and were compared to those of casein and soy protein isolates. Preparations
of alkaline-soluble total protein, albumin, globulin, and glutelin-like alkaline-soluble residual protein were produced from
two different types of defatted amaranth meals by extraction and fractionation. Although similarity can be shown between protein
patterns of legumes (including soy) and amaranth, the emulsifying and foaming properties of amaranth protein preparations
are relatively poor in comparison to the reference proteins, except foaming properties of albumin preparations. Nevertheless,
taking in mind that these properties depend on interactions with other food components and textural requirements of individual
food products, the amaranth protein preparations may be treated as potential protein sources and food ingredients. 相似文献
80.
Design and Performance of SuperSpec: An On-Chip,KID-Based,mm-Wavelength Spectrometer 总被引:1,自引:0,他引:1
E. Shirokoff P. S. Barry C. M. Bradford G. Chattopadhyay P. Day S. Doyle S. Hailey-Dunsheath M. I. Hollister A. Kovács H. G. Leduc C. M. McKenney P. Mauskopf H. T. Nguyen R. O’Brient S. Padin T. J. Reck L. J. Swenson C. E. Tucker J. Zmuidzinas 《Journal of Low Temperature Physics》2014,176(5-6):657-662
SuperSpec is an ultra-compact spectrometer-on-a-chip for mm and submm wavelength astronomy. Its very small size, wide spectral bandwidth, and highly multiplexed detector readout will enable construction of powerful multi-object spectrometers for observations of galaxies at high redshift. SuperSpec is a filter bank with planar, lithographed, superconducting transmission line resonator filters and lumped-element kinetic inductance detectors made from Titanium Nitride. We have built an 81 detector prototype that operates in the 195–310 GHz band. The prototype has a wide-band metal feed horn with a transition to microstrip that feeds the filter bank. The prototype has demonstrated optical filter bank channels with a range of resolving powers from 300 to 700, measured fractional frequency noise of \(10^{-17} \mathrm{Hz}^{-1}\) at \(1\,\) Hz. 相似文献