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排序方式: 共有187条查询结果,搜索用时 125 毫秒
71.
关于蚕茧价格问题的研究 总被引:1,自引:0,他引:1
以翔实资料,记述了明清以来各个历史时期蚕茧价格的演变,论证了茧价涨落与蚕业兴衰的关系,价值规律对生产发展的作用. 相似文献
72.
In this research, possibility of producing and processing antibacterial organic/inorganic nanocomposite polypropylene filament
yarns for permanent antimicrobial efficiency has been investigated. First PP powder and inorganic nanocomposite filler were
mixed in a twin screw extruder and modified masterbatch was produced. Continuous filament yarn was made by a pilot plant melt
spinning machine from the blend of PP granule and various blending contents of the prepared masterbatch. Pure PP and all other
combined samples showed acceptable spinnability at the spinning temperature of 240 °C and take-up speed of 2000 m/min. After
producing as-spun filament yarns, samples were drawn, textured and finally weft knitted. Physical and structural properties
of as-spun and drawn yarns with constant and variable draw ratios were investigated and also tensile and crimp properties
of textured yarns were evaluated. Moreover, the DSC, SEM, FTIR techniques have been used for characterization of samples.
Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity
reduction of modified drawn yarns has reached to 5 %. The observed improvement in the tensile properties of modified as-spun
yarns compared to the pure PP was significant. Drawing process improved generally the tensile properties of as-spun yarns.
Tensile properties of modified textured and drawn yarns were higher than the pure PP. An optimum of antibacterial activity
has been observed in the sample containing 0.75 wt% of nano-filler. It is interesting that the optimum of tensile properties
has been also obtained for the sample with maximum bioactivity. 相似文献
73.
74.
H. Bouwman 《Biology and Fertility of Soils》1998,27(4):368-373
The aim of this experiment was to investigate whether Eisenia fetida hatchlings of different ages, kept initially without food, could be used to obtain worms of a comparable development stage
(measured as growth) with similar maturation properties (measured as clitellum development). Seven groups of hatchlings, each
differing in age by 7 days (range: 0–42 days) were collected as follows. Cocoons were kept in water in multicell containers
and individuals that hatched during a 24-h period were placed on moist vermiculite with no food, at weekly intervals. The
longest period that hatchlings were fasted was 42 days, after which food was added and growth monitored for 50 days. No differences
in weight gain between the different batches were observed. Analysis of the growth curves and attainment of sexual maturity
(clitellum development) indicated no effect of age or stage of development at the onset of feeding. It was concluded that
this technique allows the production of cohorts of E. fetida, synchronised with respect to development stage, for use in toxicological and biological investigations that require control
of factors such as development stage, age and size, and in particular for use in toxicological experiments complying with
OECD regulatory procedures.
Received: 16 June 1997 相似文献
75.
E. J. Tondoh 《Biology and Fertility of Soils》1998,26(4):336-340
Hyperiodrilus africanus (Beddard) is a 12-cm to 16-cm-long earthworm, which is widely distributed in West and Central Africa. It lives in the upper
10–20 cm of the soil, and feeds on a mixture of soil and above-ground litter. Cocoons obtained in the laboratory hatched on
average 17 days after deposition and produced two juveniles on average. Paired individuals fed soil amended with 2% coffee
residues grew significantly (P<0.05) faster than those in the control soil. Daily individual weight increments were respectively 6.1 mg worm–1 day–1 and 1.0 mg worm–1 day–1 in supplemented and control soil. The generation time was short, and cocoon production reached 9.6 month–1 (i.e. 115 cocoons adult–1 year–1). When H. africanus collected from the field were raised in the laboratory, they grew slowly, laid fewer cocoons and mortality was high. Demographic
parameters indicated an improvement when H. africanus were raised in batches rather than individually. Mating enhanced cocoon production although parthenogenesis was possible.
Received: 4 April 1997 相似文献
76.
以木粉和聚乳酸为主体原料,硅烷类 KH560 等为偶联剂,PE 蜡 + 硬脂酸锌、甘油为润滑剂,
制备出木粉 / 聚乳酸 3D 打印用线材。对不同组合条件下制备出的线材其微观构造、热稳定性、官能团变
化以及拉伸强度进行了分析。结果表明,木粉粒径为 80-100 目时较为合适,铝钛酸酯 α(AlTi-α)型
对木粉表面改性效果较好,甘油对二者界面相容性的效果好于 PE 蜡 + 硬脂酸锌。木粉含量为 20%、PLA
含量为 75%、铝钛酸酯 α 型加入量为 1.5%,甘油加入量为 3.5% 时制备出来的线材,拉伸强度可达到
18.97 MPa。木粉 / 聚乳酸 3D 打印线材可生物降解,性能可控,具有广阔的应用前景。 相似文献
77.
用氨苄西林、阿莫西林、庆大霉素和阿米卡星 4种抗生素在体外作用大肠杆菌后 ,观察细菌菌量、形态变化及诱发内毒素释放的情况。结果表明 ,4种抗生素均对大肠杆菌有较好的杀菌作用 ,最小抑菌质量浓度分别为 2、2、1、0 .5mg/ L。氨苄西林和阿莫西林以不同浓度作用大肠杆菌后 ,可使菌体产生丝状体 ,尤其在 0 .5 MIC时 ,丝状体产生的量最为显著 ,这 2种药使菌体发生丝状变化的程度不一 ,尤以氨苄西林更甚。庆大霉素和阿米卡星作用大肠杆菌后 ,菌体形态未发生变化 ,但菌量明显下降。杀菌液中内毒素含量测定结果表明 ,氨苄西林和阿莫西林在不同浓度 (0 .5、2、4、8MIC)及不同作用时间 (0、2、4、6、8h)与对照组相比 ,均显著 (P<0 .0 5 )增加大肠杆菌内毒素的释放 ,且氨苄西林诱发内毒素释放的量显著 (P<0 .0 5 )高于阿莫西林 ,不同药物浓度诱发内毒素释放量的顺序为 0 .5 MIC>2 MIC>4 MIC>8MIC,不同作用时间内毒素释放量的顺序为 8h>6 h>4 h>2 h>0 h。庆大霉素和阿米卡星在不同药物浓度 (0 .5、2、4、8MIC)及不同作用时间 (0、2、4、6、8h)与对照组比较 ,可显著 (P<0 .0 5 )降低大肠杆菌内毒素的释放 ,但这 2种药间相比 ,差异不显著 (P>0 .0 5 )。 相似文献
78.
家蚕地理系统间茧丝蛋白酶抑制剂含量的比较分析 总被引:2,自引:1,他引:1
以中国系统、日本系统、欧洲系统、多化性系统品种各 11个及丝胶茧 (Nd s)、裸蛹 (Nd)等为材料 ,对茧丝蛋白酶抑制剂的含量、热稳定性及与其它主要经济性状的相关性进行了研究。结果表明 :不同家蚕品种间茧丝蛋白酶抑制剂的含量差异极显著 ,且中国系统 >日本系统 >欧洲系统 >多化性系统 ,中、日、欧 3个系统的茧丝蛋白酶抑制剂含量与多化性系统间有极显著的差异 ;中系品种C12 和日系品种J12 茧丝蛋白酶抑制剂的热稳定性很强 ,欧系品种罗尼 9号和多化性品种四海茧丝蛋白酶抑制剂的热稳定性相对较弱 ;丝胶茧 (Nd s)中有少量蛋白酶抑制剂存在 ,裸蛹 (Nd)所吐的少量丝胶中无蛋白酶抑制剂存在 ;家蚕茧丝蛋白酶抑制剂的含量与茧层量、茧层率呈极显著的正相关 ,与全茧量、死笼率、幼生率、虫蛹率无显著的相关性。 相似文献
79.
家蚕后部丝腺转氨酶活性及其与茧质性状关系 总被引:1,自引:0,他引:1
采用酶学速率法分析了8个家蚕品种末龄第3、5、7日后部丝腺谷丙转氨酶(GPT)、谷草转氨酶(GOT)活力和比活力。少丝量品种末龄GPT、GOT比活力随末龄发育逐渐升高,多丝量品种GPT比活力随末龄发育而不断下降,而GOT比活力一直较高或略有升高。GPT、GOT比活力与茧层率、茧层量、全茧量的遗传相关,末龄第3天为显著正相关,第5天相关不显著,第7天为极显著负相关。GOT、GPT比活力遗传力分别达87.44%、80.4%,可作为产丝量选择的重要生化指标。 相似文献
80.
This paper presents a computation method for filament wound pressurevessel. We have obtained the asymptotic solution for the problem.Numetical calculation shows that the result of asymptotic solution agrees with experiment and spline cllocation technique 相似文献