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排序方式: 共有1474条查询结果,搜索用时 15 毫秒
971.
The design of some processing equipment requires knowledge of the safe minimum dimensions of slots, channels or conduits for flowing granular materials. This work was prompted by the need to ensure that when narrow slots were used in equipment of this type, they were capable of providing a continuous and uninterrupted flow. There are some data in the literature for blockage of openings in the horizontal plane, but there is very little published information of any sort on vertical slots. The materials tested in this investigation included agricultural seeds (amaranth, panicum, millet, rape, wheat, barley), various plastic granules used in extrusion processes (polyethylene pellets, high impact plastic in the form of cut rod), and a sample of urea. These materials all had narrow size distributions and had maximum dimensions in the range 1 mm to 8 mm, and bulk densities in the range 600 to 800 kg/m3. Widths at blockage were obtained for vertical slots, horizontal slots and also horizontal orifices. Conservative guidelines are given for selection of the minimum size of openings for reliable flow of non-cohesive grains; for vertical slots, the ratio of minimum slot width to characteristic particle dimension is 4.6, for horizontal slots the ratio is 3.3 and for horizontal orifices, the ratio of orifice diameter to characteristic particle dimension is 6.4. 相似文献
972.
Murine central neurons express a novel member of the cdc10/SWI6 motif-containing protein superfamily
V-1 protein is a novel member of the cdc10/SWI6 motif-containing protein superfamily several members of which have been demonstrated to play crucial roles in the regulation of intracellular signaling. In the present study we examined the distribution of V-1 mRNA in the murine central nervous system (CNS). Northern analysis revealed the expression of V-1 mRNA in various regions of the brain with the following rank order: hippocampus, cerebellum > cerebral cortex, olfactory bulb, medulla oblongata, pons > thalamus. In situ hybridization also showed that V-1 mRNA is widely distributed in various regions of the brain, with parallel expression levels to those revealed by Northern analysis. Immunohistochemical analysis revealed that the V-1 protein exists in various types of neurons, mainly in cell bodies but also in dendrites, axons and possibly in synaptic areas. These expression patterns of the V-1 gene in the murine CNS suggest that the V-1 protein performs some common function in different classes of neurons. We found no significant difference in the expression level of V-1 mRNA in cerebellar granule cells between the control and mutant mice of Purkinje cell degeneration (pcd). In comparison with our previous data obtained in another mutant, staggerer, we discussed the effects of target deprivation on the expression of V-1 mRNA in cerebellar granule cells. 相似文献
973.
Multimedia databases 总被引:2,自引:0,他引:2
A.Desai Narasimhalu 《Multimedia Systems》1996,4(5):226-249
The rapidly growing interest in building multimedia tools and applications has created a need for the development of multimedia
database management systems (MMDBMSs) as a tool for efficient organization, storage and retrieval of multimedia objects. We
begin with a word about traditional database management systems (DBMSs). Then we present an overview of the MMDBMS research
issues, challenges, methods, models, and architectures. We review the state of the art and research contributions from related
disciplines. Finally, we consider possibilities and probabilities for MMDBMS research in the future. 相似文献
974.
975.
Z Guan SY Buckman BW Miller LD Springer AR Morrison 《Canadian Metallurgical Quarterly》1998,273(44):28670-28676
The inflammatory cytokine interleukin-1beta (IL-1beta) induces cyclooxygenase-2 (Cox-2) expression with a concomitant release of prostaglandins from glomerular mesangial cells. We reported previously that IL-1beta rapidly activates the c-Jun NH2-terminal/stress-activated protein kinases (JNK/SAPK) and p38 mitogen-activated protein kinase (MAPK) and also induces Cox-2 expression and prostaglandin E2 (PGE2) production. The current study demonstrates that overexpression of the dominant negative form of JNK1 or p54 JNK2/SAPKbeta reduces Cox-2 expression and PGE2 production stimulated by IL-1beta. Similarly, overexpression of the kinase-dead form of p38 MAPK also inhibits IL-1beta-induced Cox-2 expression and PGE2 production. These results suggest that activation of both JNK/SAPK and p38 MAPK is required for Cox-2 expression after IL-1beta activation. Furthermore, our experiments confirm that IL-1beta activates MAP kinase kinase-4 (MKK4)/SEK1, MKK3, and MKK6 in renal mesangial cells. Overexpression of the dominant negative form of MKK4/SEK1 decreases IL-1beta- induced Cox-2 expression with inhibition of both JNK/SAPK and p38 MAPK phosphorylation. Overexpression of the kinase-dead form of MKK3 or MKK6 demonstrated that either of these two mutant kinases inhibited IL-1beta-induced p38 MAPK phosphorylation and Cox-2 expression but not JNK/SAPK phosphorylation and activation. This study suggests that the activation of both JNK/SAPK and p38 MAPK signaling cascades is required for IL-1beta-induced Cox-2 expression and PGE2 synthesis. 相似文献
976.
RS Anthony ND McKelvie AJ Cunningham JI Craig SY Rogers AC Parker 《Canadian Metallurgical Quarterly》1998,21(5):441-446
This study investigated whether gender or smoking has an impact on immune responses to Chlamydia pneumoniae in generally healthy adults. A total of 129 twins (46 twin pairs and 37 single twins) from the Finnish Twin Cohort who had previously reported the highest discordance for smoking with their co-twins participated. C. pneumoniae-specific serum IgA and IgG antibody levels were measured by the micro-immunofluorescence test (micro-IF) at admission and 3 months later if the IgA level in the first sample was elevated. Cell-mediated immune (CMI) responses to C. pneumoniae and control antigens from heparinised blood samples were assessed by the lymphoproliferation (LP) assay. When all the subjects were pooled and analysed by gender and smoking status, marked differences in the humoral immune response between the genders were observed, irrespective of smoking status. When twin pairs solely were analysed, significantly elevated IgA antibody levels suggestive of persistent infection were found among the currently or formerly smoking men compared to their non-smoking co-twins. The CMI response showed a reciprocal trend with respect to humoral immunity. In conclusion, specific antibody levels were found to be higher in men than in women irrespective of smoking status, although smoking may further enhance the humoral response and depress the CMI response in men. 相似文献
977.
978.
The purposes of this study were to assess the quality of marital life and to investigate the most serious problem in the marital relationships of Korean spinal cord injured patients. 30 spinal cord injured (SCI) couples (SCI husbands and their non-disabled wives) who were married prior to injury and 30 able-bodied (AB) couples participated in a questionnaire study. The quality of marital life was measured with three parameters: marital stability, marital adjustment, and marital satisfaction. The results were as follows: (1) The marriage of chronic SCI couples was not noticeably unstable when compared with that of AB couples; (2) There was no significant difference in dyadic adjustment and marital satisfaction between SCI couples and AB couples; (3) There was no significant difference in marital stability, marital adjustment, and marital satisfaction between SCI husbands and their wives; (4) SCI couples had more cohesive marital relationships and SCI husbands expressed less affection to their wives than AB husbands and (5) Sex was the most serious problem in marriages of SCI couples. In conclusion: (1) the quality of marital life in chronic SCI couples is not highly different from that of AB couples; (2) There is no significant difference in the quality of marital life between chronic SCI husbands and their non-disabled wives; and (3) It is considered necessary that rehabilitation program for SCI patients should include information on the altered physiology of sexual function of SCI patients and subsequent mutual adaptation to changed sexual function. 相似文献
979.
The Bard Atherectomy Catheter is a new rotational atherectomy device that consists of a flexible, hollow, thin-walled cutting catheter that, while rotated at 1,500 revolutions per minute, is advanced across the lesion over a special spiral guidewire system. We report the initial clinical experience with this device in 20 peripheral lesions in ten patients. The majority of patients were treated for limb salvage. All lesions were successfully intervened on by atherectomy followed by adjunctive balloon angioplasty. A reduction to less than 50% stenosis was achieved in 13 of the 20 lesions (65%) after atherectomy but in all 20 lesions (100%) after adjunctive angioplasty for all lesions and stenting for dissections in two. Baseline minimal lesion lumen diameter was 0.8 +/- 0.7 mm with a reference vessel diameter of 4.2 +/- 1.7 mm (75 +/- 21% stenosis). The lumen improved to 2.0 +/- 0.8 mm (45 +/- 19% stenosis) (P < 0.001) following atherectomy and to 3.9 +/- 1.9 mm (13 +/- 16% stenosis) (P < 0.001) after adjunctive angioplasty. The average weight of removed atheroma was 45 +/- 58 mg. All ten patients had initial improvement in symptoms. At 6 months follow-up there was persistent improvement in eight patients and two subjects had undergone amputations. Our early clinical experience with this low profile, flexible atherectomy device, that enables extraction of a large amount of atheroma, suggests that it will become a valuable addition to current atherectomy technologies in small- and medium-sized vessels. The value of this device in coronary vessels is under investigation. 相似文献
980.