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排序方式: 共有228条查询结果,搜索用时 375 毫秒
31.
Samit Kumar Nandi Biswanath Kundu Samir Kumar Ghosh Dipak Kumar De Debabrata Basu 《Journal of veterinary science (Suw?n-si, Korea)》2008,9(2):183-191
The present study was undertaken to evaluate porous hydroxyapatite (HAp), the powder of which was prepared by a novel aqueous solution combustion technique, as a bone substitute in healing bone defects in vivo, as assessed by radiologic and histopathologic methods, oxytetracycline labeling, and angiogenic features in Bengal goat. Bone defects were created in the diaphysis of the radius and either not filled (group I) or filled with a HAp strut (group II). The radiologic study in group II showed the presence of unabsorbed implants which acted as a scaffold for new bone growth across the defect, and the quality of healing of the bone defect was almost indistinguishable from the control group, in which the defect was more or less similar, although the newly formed bony tissue was more organized when HAp was used. Histologic methods showed complete normal ossification with development of Haversian canals and well-defined osteoblasts at the periphery in group II, whereas the control group had moderate fibro-collagenization and an adequate amount of marrow material, fat cells, and blood vessels. An oxytetracycline labeling study showed moderate activity of new bone formation with crossing-over of new bone trabeculae along with the presence of resorption cavities in group II, whereas in the control group, the process of new bone formation was active from both ends and the defect site appeared as a homogenous non-fluoroscent area. Angiograms of the animals in the control group showed uniform angiogenesis in the defect site with establishment of trans-transplant angiogenesis, whereas in group II there was complete trans-transplant shunting of blood vessel communication. Porous HAp ceramic prepared by an aqueous combustion technique promoted bone formation over the defect, confirming their biologic osteoconductive property. 相似文献
32.
Reduction in the mRNA expression of sVEGFR1 and sVEGFR2 is associated with the selection of dominant follicle in cows 下载免费PDF全文
PV Ortega Serrano A Guzmán CG Hernández–Coronado H Castillo‐Juárez AM Rosales‐Torres 《Reproduction in domestic animals》2016,51(6):985-991
The vascular endothelial growth factor (VEGF) is essential for follicular development by promoting follicular angiogenesis, as well as for the proliferation and survival of granulosa cells. The biological effects of VEGF are regulated by two membrane receptors, VEGFR1 and VEGFR2, and two soluble receptors, sVEGFR1 and sVEGFR2, which play an antagonistic role. Thus, the objective of this study was to identify the mRNA expression pattern of total VEGF, VEGFR1, VEGFR2, sVEGFR1 and sVEGFR2 in bovine preselected follicles (PRF) and post‐selected follicles (POF). The mRNA expression of these five genes in both granulosa cells (GC) and theca cells (TC) was compared between follicles classified as PRF and POF based on their diameter and on their ratio of estradiol/progesterone (E2/P4). Results showed a lower expression of mRNA of sVEGFR1 and sVEGFR2 in POF than in PRF (p < .05). Regarding the mRNA expression of total VEGF, VEGFR1 and VEGFR2, there was no difference between POF and PRF follicles (p > .05). Our results showed that the mRNA expression of VEGFR2 and sVEGFR1 was more abundant than the expression of VEGFR1 and sVEGFR2, while GC was the main source of mRNA for total VEGF. On the other hand, TC was the follicular compartment where the receptors were most expressed. Our results suggest that non‐dominant follicles maintain a greater concentration of the mRNA expression of both membrane and soluble VEGF receptors. On the other hand, follicular dominance is related to a reduction in the mRNA expression of sVEGFR1 and sVEGFR2, which may favour VEGF binding with VEGFR2 and, hence, improve the follicular health and development. 相似文献
33.
G Medeiros-Ribeiro AM Bratkovski TI Kamins DAA Ohlberg RS Williams 《Science (New York, N.Y.)》1998,279(5349):353-355
Chemical vapor deposition of germanium onto the silicon (001) surface at atmospheric pressure and 600 degrees Celsius has previously been shown to produce distinct families of smaller (up to 6 nanometers high) and larger (all approximately 15 nanometers high) nanocrystals. Under ultrahigh-vacuum conditions, physical vapor deposition at approximately the same substrate temperature and growth rate produced a similar bimodal size distribution. In situ scanning tunneling microscopy revealed that the smaller square-based pyramids transform abruptly during growth to significantly larger multifaceted domes, and that few structures with intermediate size and shape remain. Both nanocrystal shapes have size-dependent energy minima that result from the interplay between strain relaxation at the facets and stress concentration at the edges. A thermodynamic model similar to a phase transition accounts for this abrupt morphology change. 相似文献
34.
Self-oriented regular arrays of carbon nanotubes and their field emission properties 总被引:4,自引:0,他引:4
S Fan MG Chapline NR Franklin TW Tombler AM Cassell H Dai 《Science (New York, N.Y.)》1999,283(5401):512-514
The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology. 相似文献
35.
Yasmen El-Sisi Ayman F. Omar Samir A. Sidaros Mohsen M. Elsharkawy Xavier Foissac 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(3):779-784
‘Candidatus Phytoplasma australasia’ causes important damages to the Egyptian vegetable crop production. A prerequisite for controlling the different diseases it causes to eggplant, tomato and squash, is to trace its propagation pathways. To allow the differentiation of ‘Ca. P. australasia’ strains, a multilocus sequence analysis protocol was developed. Four conserved phytoplama genes namely tuf, secY, dnaK and dppA, were selected among the CDS of a ‘Ca. P. aurantifolia’ genome draft. The corresponding genes were PCR amplified from tomato, eggplant and squash collected in 2010 from the governorates Sharkia, Elmynia and Beni sueif, as well as from Catharanthus roseus periwinkles collected in 2013 from Kafrelsheikh governorate. Sequence comparisons showed no diversity among the Egyptian isolates of ‘Ca. P. australasia’ that also constitute a distinct cluster within the 16SrII-D taxonomic subgroup. This low diversity supports a common epidemiology for the different diseases affecting vegetable crops and periwinkle in Egypt and suggests that future investigations on insect vector should focus on polyphagous leafhoppers. 相似文献
36.
Mohammad H. Ahmad Amani M. D. El Mesallamy Fatma Samir Faten Zahran 《Journal Of Applied Aquaculture》2013,25(4):289-298
Four isonitrogenous (30% crude protein) and isocaloric (4.40 kcal/g) experimental diets were formulated to contain 0.0% (control), 0.5%, 1.0%, or 1.5% cinnamon. The diet containing 1% cinnamon resulted in significantly greater (P < 0.05) specific growth rate (SGR), feed conversion ratio (FCR), feed efficiency ratio (FER), protein efficiency ratio (PER), apparent protein utilization (APU), and energy utilization (EU). In regard to body composition, there was no significant difference in dry matter, protein, lipids, and ash (P > 0.05) contents due to cinnamon supplementation. Blood plasma profile showed an improvement in hemoglobin (HB), red blood cell (RBCS), hematocrite (PCV), total protein, and total lipids, while there was a decrease in creatinin, urea, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glucose in fish fed 1% cinnamon. Cinnamon was found to have an antibacterial activity antagonistic to Aeromonas hydrophila infection in fish. Performance and FCR improvement translated into a 10% decrease in feed costs associated with the 1% cinnamon diet. 相似文献
37.
38.
The lowland and coastal regions are the areas where cotton is cultivated in Yemen. The land used for this purpose exceeds
120 acres and expandable in the upcoming seasons. We have selected the earlier two varieties of cotton fibers cultivated in
two different areas Abyan and Zabid. Wide Angle X-ray Scattering (WAXS) data from these fibers have been recorded and analysed
to obtain the micro-structural parameters with the application of Line Profile Analysis (LPA). Linked Atom Least Squares (LALS)
program has been used to obtain molecular structure and packing in these fibers. For the first time micro-structural parameters
of these cotton fibers cultivated in Yemen are computed and reported. This study will be of help to understand the structure-property
relation in these cotton fibers. 相似文献
39.
Bhavesh Trangadia Samir Kumar Rana Falguni Mukherjee Villuppanoor Alwar Srinivasan 《Tropical animal health and production》2010,42(2):203-207
This study was carried out to investigate the prevalence of bovine brucellosis and infectious bovine rhinotracheitis (IBR) in organized dairy farms with history of abortion in India. ELISA and Rose Bengal Plate Test (RBPT) were used to detect the seropositive animals and the test results indicated that 22.18% and 13.78% animals were declared as sero-positive by ELISA and RBPT, respectively. Milk Ring Test (MRT) was carried out only in one farm and 12.82% of the tested animals were turned positive. Culture examination analysis of milk samples, two animals revealed the presence of organisms indistinguishable from Brucella spp. The organism was confirmed as brucella by morphological characteristics and biochemical tests. An overall sero-prevalence of antibodies against IBR was found to be 60.84%. None of the genital and nasal swab samples was found to be positive for presence of bovine herpesvirus -1 (BHV-1) on repeated passage in Madin-Darby Bovine Kidney (MDBK) cell lines. Brucella and IBR considered as the causal agent for abortions in these farms. The present study indicates the urgent need and the necessity for control of these infectious diseases which cause heavy economic losses to the organized farms. 相似文献
40.
Samir C. Debnath Kenneth B. Mcrae 《The Journal of Horticultural Science and Biotechnology》2013,88(6):744-752
SummaryAn efficient system to regenerate shoots in vitro on excised leaves of lingonberry (Vaccinium vitis-idaea L.) was developed. Leaf explants from shoot-proliferating cultures produced multiple shoots without an intermediary callus phase on zeatin (ZN)-containing shoot induction media within 3–4 weeks of culture initiation. Cultivars Regal and Splendor, and one clone from a natural stand in Estonia (ECL1), were used in the first experiment. Young expanding leaves with the adaxial side touching the culture medium, and maintained for 7 d in darkness, produced the best results. There were significant genotypic differences in adventitious shoot formation. A second experiment studied the effects of ten concentrations of three cytokinins: ZN at 5, 10, 20, 30 and 40 μM; 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (thidiazuron, TDZ) at 0.1, 1, 5 and 10 μm; and 6-(γ-γ-dimethylallylamino) purine (2ip) at 25 μM were compared with leaf segments of different polarity in ‘ECL1’. Zeatin was found to be more effective than TDZ or 2iP as an inductive signal for regenerating many vigorous shoots. Zeatin induced multiple shoot formation at all concentrations tested, but maximum morphogenic response was observed at 20 to 30 μM. The media containing TDZ generally promoted more callus formation and suppresed shoot elongation. In a third experiment with the lingonberry cultivar Erntedank and the clone ‘ECL1’, a new medium developed for lingonberry shoot culture proved more effective than the modified Murashige and Skoog medium for regenerating shoots on leaf explants. Elongated shoots were excised and rooted directly on a 2 peat:1 perlite (v/v) medium after dipping in 0.8% indole-3-butyric acid. Rooted plantlets were acclimatized under greenhouse conditions to evaluate somaclonal variation. 相似文献