共查询到20条相似文献，搜索用时 15 毫秒
1.
Stiles FG 《Science (New York, N.Y.)》1971,173(3999):818-821
The male Anna Hummingbird accommodates seasonal changes in energy demands by varying its allocation of time and energy among different activities; total energy expenditures change relatively little. Augmented terrritorial defense during the breeding season is made possible by increased feeding efficiency due to the availability at this time of very nectar-rich flowers. 相似文献
2.
针对秸秆作为生物质能使用时在压缩储运过程中耗能高的状况,提出铰制压缩的储运技术方案,选择类似制绳的铰制机械装置实现秸秆低能耗压缩储运,重点讨论了铰制机械装置的机构方案,对秸秆作为生物质能使用时在压缩储运过程中实现高效低耗有积极效果和参考作用。 相似文献
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试验对产蛋中期AA肉种鸡进行能量限饲,探讨其对子代生长性能、血液生化指标及肌节长度的影响。选用产蛋中期肉种母鸡288羽,分为4个处理组,每组6个重复,每个重复12只。对照组饲喂基础饲粮,试验组日粮能量水平分别为基础饲粮能量的80%、70%、50%,对照组和实验组均限饲且饲喂量相同,于产蛋中期(40~42周龄)进行人工授精、孵化得到子代。每组选用90只肉仔鸡公雏,每组设6个重复,每个重复15只,自由采食同种日粮,试验期为49 d。结果表明,①生产性能:与对照组相比,50%、70%能量组仔鸡初生重显著降低(P<0.05),80%能量组仔鸡49日龄体重显著升高(P<0.05)。②血液生化指标:母体能量限饲显著降低了28日龄各组仔鸡血清中ALB的含量(P<0.05),显著提高了50%能量组IGF-1的水平(P<0.05)。③肌节长度:与对照组相比,50%、70%能量组1日龄肉鸡腿肌肌节长度显著降低(P<0.05),70%、80%能量组28日龄肉鸡腿肌肌节长度显著升高(P<0.05),50%能量组49日龄肉鸡腿肌肌节长度显著增大(P<0.05)。结果表明,肉种鸡产蛋中期能量限饲对子代生长发育有显著影响,并且子代在生长过程中表现出补偿生长作用。 相似文献
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We described three uses of energy for which greater efficiency is feasible: transportation, space heating, and air conditioning. Shifts to less energy-intensive transportation modes could substantially reduce energy consumption; the magnitude of such savings would, of course, depend on the extent of such shifts and possible load factor changes. The hypothetical transportation scenario described here results in a 22 percent savings in energy for transportation in 1970, a savings of 2800 trillion Btu. To the homeowner, increasing the amount of building insulation and, in some cases, adding storm windows would reduce energy consumption and provide monetary savings. If all homes in 1970 had the "economic optimum" amount of insulation, energy consumption for residential heating would have been 42 percent less than if the homes were insulated to meet the pre-1971 FHA standards, a savings of 3100 trillion Btu. Increased utilization of energy-efficient air conditioners and of building insulation would provide significant energy savings and help to reduce peak power demands during the summer. A 67 percent increase in energy efficiency for room air conditioners would have saved 15.8 billion kilowatt-hours in 1970. In conclusion, it is possible-from an engineering point of view-to effect considerable energy savings in the United States. Increases in the efficiency of energy use would provide desired end results with smaller energy inputs. Such measures will not reduce the level of energy consumption, but they could slow energy growth rates. 相似文献
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Molecular dynamics simulations have been used to investigate the dynamics and redistribution of energy during the impact of a nanocrystal with adsorbed liquid films. Although impact of a 32-molecule NaCl cluster on a solid surface at 3 kilometers per second leads to melting, disordering, fragmentation, and rebounding, the same size cluster colliding with a liquid neon film transfers its energy efficiently to the liquid for a controlled soft landing. Impact on a higher density film (argon) leads to rapid attenuation of the cluster velocity, accompanied by fast heating. Subsequent disordering, melting, and fast cooling by evaporation of argon quench the cluster to a glassy state. These results suggest a method for the controlled growth of nanophase materials. 相似文献
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为明确沈阳地区水稻生产对环境的影响,促进水稻清洁生产水平提升,采用生命周期评价法,以1 t稻谷为功能单位,对沈阳地区水稻生产系统的原料开采、农资生产和水稻种植阶段的10种潜在环境影响进行评价。结果表明,水稻生产对环境影响潜力较大的是水体毒性、富营养化、土壤毒性和人体毒性,环境影响指数分别为16.278、1.558、1.457和0.960。加权处理后,环境影响综合指数为2.267。水稻种植阶段化肥和农药的大量使用,增加了该阶段对环境酸化、富营养化、水体毒性和土壤毒性的影响潜值;其中化肥的大量投入,尤其是氮肥的大量投入,加重了其上游生产环节的能源消耗,从而提高了农资生产阶段对全球变暖的贡献率;而生产阶段能源的大量消耗又扩大了原料需求量,从而增加了原料开采阶段重金属排放量,使得潜在人体毒性成为原料开采阶段的主要环境影响。因此,减少化学肥料和农药的使用,是控制水稻生产潜在环境影响的关键。 相似文献
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通过计算分析说明仅凭能量平衡并不能完全真实地反映能量利用的合理程度,必须既要考虑“量”的守恒性,又要考虑“质”的不守恒性,才能找到提高热媒炉(火用)效率的途径。提高热媒炉(火用)效率的关键是降低燃烧过程和传热过程的炯损失。从实际出发采用提高绝热燃烧温度的措施,如减小过剩空气系数或预热空气等;在热媒炉工艺允许的情况下提高热媒温度也是一种有效的方法。 相似文献
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Solar availability for space heating on coldest-weather days has been determined from an analysis of SOLMET data tapes. The tapes contain hourly readings of insolation and ambient temperature over the period from 1953 through 1975. Scatter diagrams of insolation versus heating degree-days, compiled on a daily basis, indicate a wide variation in the insolation level, even during coldest-weather periods. For all but one of the eight sites studied, the peak-day backup energy requirement of the solar system was in excess of 85 percent of the peak-day energy requirement of the conventional (nonsolar) heating system. 相似文献
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LIYan-fei WANGZhe NIUShu-ling 《东北农业大学学报(英文版)》2004,11(2):160-162
24 healthy periparturient cows were randomly allocated into three groups and fed 100% energy diet(NRO standard diets), 120% energy diet and 80% energy diet, respectively, beginning at 28 days prior to anticipated parturition. After parturition, all the cows were provided with the lactation ration ad libitum until the day 56 postpartum.The objectives of the study were to investigate the effect of energy intake during the dry period on the production performance in the postpartum cows. The results indicated that the cows fed with high energy diet during the dry period had a lower dry material intake (DMI) and reduced milk production and a significant body weight (BW) loss compared with the cows fed with 80% energy diet and 100% energy diet. The results suggested that energy intake during the dryperiod was an important factor that influences and regulates DMI, milk production and energy equilibration of postparturient cows. 相似文献
11.
Böhm-Vitense E 《Science (New York, N.Y.)》1984,223(4638):777-784
The increase in temperature outward from the surface of a stellar photosphere can be understood by looking at the local energy balance. The relatively high-density stellar photosphere is cooled effectively by radiative energy loss penetrating the optically thin corona. For the low-density chromosphere and corona, if the energy input cannot be balanced by radiative energy losses, the temperature will rise steeply, possibly up to 1 million degrees or more. Coronal heating and emission appear to be strongly influenced by magnetic fields, leading to large differences in x-ray emission for otherwise similar stars. Comparatively small variations are seen in the overall chromospheric emission of stars. Chromospheres are probably mainly heated by shock-wave energy dissipation, modified by magnetic fields. 相似文献
12.
Fleischer RL Haines EL Hanneman RE Hart HR Kasper JS Lifshin E Woods RT Price PB 《Science (New York, N.Y.)》1970,167(3918):568-571
Particle tracks in Apollo 11 samples are dominantly of cosmic ray and solar origin: primary galactic and solar flare particles, likely spallation recoil tracks, and possible solar-wind heavy particles. The energy spectrum of irongroup nuclei is inferred from track density gradients in surface layers, and a limit of < 10(-7) centimeter per year is deduced for the surface erosion rate. From cosmic ray tracks in rock and core samples it is clear that the lunar soil is stirred often during each few million years. X-rays reveal augite, anorthite, olivine, ilmenite, troilite, nonmeteoritic iron, and assorted glasses, but no major structural damage. Hydrogen, helium, and other gases in the fines are compatible with expected solar wind ratios. 相似文献
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中美日农业生产性能源消费对比研究 总被引：1，自引：0，他引：1
对比分析了中美日三个国家的农业现代化及农业生产性能源的消费情况,发现美国和日本在发展农业现代化的过程中均出现了诸如环境污染、土壤退化及农产品质量下降等问题。在此基础上,提出我国在推进农业现代化的进程中,应该吸取美日的经验教训,降低对石油的依赖,发展资源节约型的现代农业,提高农业机械的使用效率,减少化肥和农药使用,从而避免环境污染问题。 相似文献
14.
Sykes LR Kisslinger JB House L Davies JN Jacob KH 《Science (New York, N.Y.)》1980,210(4476):1343-1345
Historical documents indicate that great earthquakes ruptured at least a 500-kilometer-long segment of the plate boundary near the Alaska Peninsula in 1788 and 1847. At least half of a major seismic gap in the Shumagin Islands ruptured during those shocks but has not experienced a great earthquake for at least 77 years. Large shocks along this and other plate boundaries occur in bursts followed by several decades during which there is very little energy release. 相似文献
15.
《农业科学学报》2016,(8)
This study was conducted to investigate the effects of dietary energy and protein dilution from age 8 to 14 d on growth performance,clinical blood parameters,carcass yield,and tibia parameters of broilers.Treatments were assigned in a completely randomized manner with factorial arrangement(4x4) including 4 levels of energy dilution and 4 levels of protein dilution.All birds were fed the same diet during the remaining period of time.The feeds were weighed every week,and the birds were weighed at 7,14,and 42 d.At 14 d,blood samples were taken for clinical chemistry measurements,and 4birds from each replicate were sacrificed to measure carcass yield and tibia parameters at 42 d.From 8 to 14 d,average daily feed intake(ADFI) of the 20%protein dilution group increased significantly compared with that of the 10%protein dilution group(P0.05).The feed conversion ratio(FCR) of the group with 30%protein dilution and 15%energy dilution creased the most among all treatment groups.From 15 to 42 d,the ADFI and FCR of the 20%protein dilution group were greater than those of the 0 and 10%protein dilution groups(P0.05),and the FCR of the 15%energy dilution group increased significantly(P0.05).At 42 d,body weight(BW) of the 15%energy dilution group was less than that of the other groups(P0.05).Significant interactions were observed in ADFI,FCR,and BW at 42 d of age between energy dilution and protein dilution(P0.05).At 14 d,serum total protein levels of birds in the 20 and 30%protein dilution groups decreased significantly compared to that of the 10%protein dilution group(P0.05).Blood urea nitrogen concentration of birds in the 20 and 30%protein dilution groups decreased significantly compared with those in 0 and 10%protein dilution groups(P0.05).Triacylglycerol concentration of birds in the 20%protein and 10%energy dilution groups decreased significantly compared with that of the 0 dilution group(P0.05).The carcass yields were unaffected by dilution of energy and protein(P0.05).The bone breaking strength of the 15%energy dilution group decreased significantly compared with that of the5%energy dilution group(P0.05).This study suggested that dietary protein and energy reduced 10%from 8 to 14 d of age can not affect the growth performance and other indexes in broilers. 相似文献
16.
Photosynthetic properties of the mid-vein and leaf lamina of field-grown,high-yield hybrid rice during senescence 
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下载免费PDF全文 Previous studies with rice (Oryza sativa L.) have shown that the different components of the photosynthetic apparatus are not uniformly synthesized or degraded during senescence. However, while most of those studies have focused on the leaf lamina, few have addressed senescence-associated chloroplast function or leaf physiology. Here, we investigated the photosynthetic properties of the mid-vein and leaf lamina in a high-yield hybrid rice cultivar (Liangyoupei 9, LYP9) during the senescence stage. Assimilation and transpiration decreased more slowly in the mid-vein than in the lamina during senescence, suggesting more sustained photosynthesis in the mid-vein, as well as stronger heat dissipation. Two-dimensional gel electrophoresis suggested that photosynthesis and energy metabolism were less affected by senescence in the mid-vein than in the leaf lamina. During late senescence, the excess energy dissipation in the mid-vein through the xanthophyll cycle had a higher active photosynthetic capacity than in the leaf lamina, and we inferred that the mid-vein and leaf lamina of LYP9 rice differed in terms of their maturation. Taken together, these results provide new insights into the underlying mechanisms of senescence of the rice mid-vein and associated physiology. 相似文献
17.
Diabetes, obesity, and the brain 总被引：1，自引：0，他引：1
Recent evidence suggests a key role for the brain in the control of both body fat content and glucose metabolism. Neuronal systems that regulate energy intake, energy expenditure, and endogenous glucose production sense and respond to input from hormonal and nutrient-related signals that convey information regarding both body energy stores and current energy availability. In response to this input, adaptive changes occur that promote energy homeostasis and the maintenance of blood glucose levels in the normal range. Defects in this control system are implicated in the link between obesity and type 2 diabetes. 相似文献
18.
鲁宁管道添加CE—S原油改性剂工业性试验 总被引：3，自引：1，他引：2
为了提高管道输油效益,从１９９４年起,开始对鲁宁线原油进行添加改性剂的研究,并于１９９５年７月在鲁宁线做了加剂输送的工业性试验,经过一年多时间的加剂运行,取得了明显的社会效益和良好的经济效益。重点介绍了鲁宁线加改性剂的目的,改性剂的研制和室内试验、加剂试验过程,各阶段的运行情况,加剂后的能耗及加剂试验所得出的结果。 相似文献
19.
经检验两年推算消化能需要量回归公式的剩余标准差、回归系数及截距,均无显著差异。故将两年数据合并,得出推算消化能需要量的新回归公式。以预期日增重代回归公式的x,制订了甘肃黑猪20—90公斤阶段消化能饲养标准。将用新回归公式推算的能值与其它饲养标准规定量作比较,能值接近,为其共性。其差异反映了甘肃黑猪的特殊性。饲喂甘肃黑猪宜用本能量标准。经检验两年可消化蛋白质需要量回归公式的重要参数,其中4/9差异显著,不宜合并。 相似文献
20.
通过对我国五省十七县的农村能源资源和消费结构的抽样调查研究,结果表明:农村能源资源总量在“六·五”期间增长35.69%,人均资源占有量增长30.41%,其中除小矿煤在农村能源资源结构中的比重上升外;其它资源量的比重均下降。农村能源总消费量增长31.58%;其中商品能源耗量增长98.30%,生物质能耗量下降8.31%。乡镇企业耗能增长428.51%,农业生产耗能增长58.27%,农村生活耗能增长2.21%。人均总耗能增长25%.其中人均生活耗能下降1.61%。研究分析了引起上述变化的原因,提出中国农村能源资源及消费结构在“七·五”期间的发展趋势。 相似文献