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排序方式: 共有835条查询结果,搜索用时 93 毫秒
791.
792.
Gruber M 《Applied optics》2004,43(2):463-470
Even in the semiconductor industry, free-space optical technology is nowadays seen as a prime option for solving the continually aggravating problem with VLSI chips, namely, that the interconnect technology has failed to keep pace with the increase in communication volume. To make free-space optics compatible with established lithography-based design and fabrication techniques the concept of planar integration was proposed approximately a decade ago. Here its evolution into a photonic microsystems engineering concept is described. For demonstration, a multichip module with planar-integrated freespace optical vector-matrix-type interconnects was designed and built. It contains flip-chip-bonded vertical-cavity surface emitting laser arrays and a hybrid chip with an array of multiple-quantum-well p-i-n diodes on top of a standard complementary metal-oxide semiconductor circuit as key optoelectronic hardware components. The optical system is integrated into a handy fused-silica substrate and fabricated with surface-relief diffractive phase elements. It has been optimized for the given geometrical and technological constraints and provides a good interconnection performance, as was verified in computer simulations on the basis of ray tracing and in practical experiments. 相似文献
793.
Onyilagha JC Lazorko J Gruber MY Soroka JJ Erlandson MA 《Journal of chemical ecology》2004,30(1):109-124
Thirty-seven flavonoid compounds (9 flavones, 18 flavonols, 8 flavanones, and 2 flavanonols) were investigated for their effect on feeding choice with bertha armyworm (Mamestra configurata Walker; BAW). Feeding choice was dependent upon subtle differences in biochemical structure. Unsubstituted flavone and flavanone were the strongest feeding deterrents in the choice bioassay, while 7.4'-dihydroxyflavone and dihydroquercetin stimulated BAW to feed. The constitutive flavonoids of Brassica napus, isorhamnetin-3-sophoroside-7-glucoside and kaempferol-3,7-diglucoside, were effective deterrents when supplemented at concentrations higher than endogenous levels. In a no-choice bioassay, flavone reduced both larval weight as well as larval and pupal development time. 相似文献
794.
795.
Sirolimus (SRL), a potent immunosuppressant, is currently being investigated in phase III trials for prophylaxis of renal transplant rejection. The mechanism of action of SRL is a blockade of the response of T and B cells to cytokines, thereby preventing cell cycle progression in G1 and consequently cell proliferation. There seems to be a good correlation between SRL concentrations, estimated as exposure by the area under the concentration versus time curve, and trough whole blood concentration, so that therapeutic monitoring may be done by trough levels only. Because of the low frequency of allograft rejection, there has been no documented correlation between trough concentrations and efficacy. Trough SRL concentrations of 15 ng/ml or higher seem to be associated with an increased frequency of adverse effects. Drug-associated toxicities include thrombocytopenia, leukopenia, and increases in cholesterol and triglyceride levels. The drug has synergy with cyclosporine (CsA) in vitro as well as in animal and clinical studies. In phase II trials the combination of SRL-CsA therapy reduced the frequency of acute rejection episodes, permit withdrawal of concomitant corticosteroid therapy, and allowed reduction of CsA dosages in nonblack patients. 相似文献
796.
S Frosch A Gruber C Jones S Myers E Noel A Westerlund T Zavisin 《Canadian Metallurgical Quarterly》1997,11(12):891-906
This study was conducted to identify the long term effects of traumatic brain injury (TBI) on the roles of caregivers. The subjects consisted of 155 caregivers of survivors with TBI who were randomly selected from 15 midwestern state brain injury association databases. A questionnaire was developed by the researchers to determine factors affecting role changes of caregivers. The Role Checklist, by Barris, Oakley and Kielhofner, was also included with the questionnaire. Both were mailed to each selected caregiver and used for data gathering. The data obtained were analysed to determine existing trends in the data. Graphs were utilized to depict the trends that was identified. The following trends and conclusions established by this research include: (a) behavioural effects of the survivor with a TBI are associated with the number of role changes experienced by caregivers; (b) participation in support systems is associated with the number of role changes experienced by caregivers; and (c) caregivers who care for a person with a TBI in the home will show a larger number of role changes than those who do not provide direct care for a person with a TBI. 相似文献
797.
Gruber M. Ken-Yuh Hsu 《IEEE transactions on pattern analysis and machine intelligence》1997,19(2):136-139
In this paper the effects of noise with nonzero mean on existing moment-based image normalization methods are studied. Several modifications to reduce noise sensitivity are presented and tested. They involve nonlinear mapping and fractional- and negative-order moments 相似文献
798.
Pfistner C. Weber R. Weber H.P. Merazzi S. Gruber R. 《Quantum Electronics, IEEE Journal of》1994,30(7):1605-1615
The thermally induced beam distortions in end-pumped Nd:YAG, Nd:GSGG, and Nd:YLF rods were analyzed and the influence of edge- and face-cooling was investigated. The distributions of temperature, stress, and strain in the crystals were calculated by finite element analysis. Based on these data, the space-resolved changes of the refractive index were determined considering thermal dispersion, surface deformation, and strain-induced birefringence. The resulting optical path difference for one round-trip in the end-pumped rods was integrated numerically. For each rod, the induced thermal lens was determined over the extent of the pump spot radius. The calculations of the optical path difference were experimentally confirmed by investigations using a modified Twyman-Green interferometer with a polarized HeNe probe beam at 633 nm under lasing and nonlasing conditions 相似文献
799.
Estradiol-induced synthesis of vitellogenin. III. The isolation and characterization of vitellogenin messenger RNA from avian liver 总被引:3,自引:0,他引:3
G Ab WG Roskam J Dijkstra J Mulder M Willems A Van der Ende M Gruber 《Canadian Metallurgical Quarterly》1976,454(1):67-78
The messenger RNA of the hormone-induced protein vitellogenin was isolated from the liver of estrogen-treated roosters. Starting from total polysomal RNA, the vitellogenin messenger was purified 67-fold by oligo (dT)-cellulose chromatography and sizing on a sucrose gradient. The messenger was translated in vitro into a 170 000 dalton polypeptide chain, having the immunochemical characteristics of vitellogenin. From electrophoretic and immunochemical analysis of the in vitro product of translation at least 63% of the messenger activity of the RNA preparation could be attributed to vitellogenin mRNA. Gel electrophoresis of the most purified fraction revealed residual contamination with the larger ribosomal RNA species. The molecular weight of the messenger RNA molecule, obtained by contour length measurements in the electron microscope, lies between 2.5 - 10(6) and 2.8 - 10(6). 相似文献
800.
Hormonal control of vitellogenin synthesis in avian liver 总被引:3,自引:0,他引:3
Estradiol induces the synthesis of vitellogenin in the avian liver. We describe the precursor-product relationship between vitellogenin and the yolk proteins phosvitin and lipovitellin. The high rate of vitellogenin synthesis is a consequence of the accumulation of a stable messenger RNA. We suggest that estradiol acts at the level of the genome by opening a hitherto non-transcribed gene. 相似文献