共查询到20条相似文献，搜索用时 437 毫秒
1.
Zimmermann S Wixforth A Kotthaus JP Wegscheider W Bichler M 《Science (New York, N.Y.)》1999,283(5406):1292-1295
Photonic signals were efficiently stored in a semiconductor-based memory cell. The incident photons were converted to electron-hole pairs that were locally stored in a quantum well that was laterally modulated by a field-effect tunable electrostatic superlattice. At large superlattice potential amplitudes, these pairs were stored for a time that was at least five orders of magnitude longer than their natural lifetime. At an arbitrarily chosen time, they were released in a short and intense flash of incoherent light, which was triggered by flattening the superlattice amplitude. 相似文献
2.
3.
Eisner T Eisner HE Hurst JJ Kafatos FC Meinwald J 《Science (New York, N.Y.)》1963,139(3560):1218-1220
The cyanogenic secretion of the polydesmoid millipede Apheloria corrugata (Wood) is discharged from paired, serially arranged glands, each consisting of two compartments. In one compartment is stored an undissociated cyanogenic compound, and in the other, a chemical factor that triggers cyanogenesis. The gland is constructed in such a way that the contents of the two compartments are mixed, and cyanogenesis is initiated, at the very instant of discharge. The stored cyanide precursor may be mandelonitrile. 相似文献
4.
我国古代贮藏物害虫防治的主要策略与方法 总被引：1，自引：0，他引：1
根据大量的古籍及相关文献,系统研究了我国古代对贮藏物害虫防治的主要策略和方法,分析了“密封法”、生态因子调控法、利用植物性杀虫物质进行处理、以及采用药物和物理曝晒相结合等方法对害虫控制的原理;探讨现代仓虫防治技术的历史渊源;指出挖掘和深入研究古代储藏害虫防治的措施并加以协调运用,对于开展当今贮藏物害虫的防治有十分重要的意义。 相似文献
5.
Andrea Luvisi Mario PaganoRoberto Bandinelli Enrico Rinaldelli Barbara Gini Mario Scartòn Giorgio Manzoni 《Computers and Electronics in Agriculture》2011,75(2):368-371
A method for combining data stored in an RFID microchip implanted inside grapevine plants and a GPS system is described. GIS software was used to register geographic coordinates of detected points, and to develop a specific database in which information useful for the positioning phase are stored. The final product is a digital map accessible via mobile or desktop systems that represents the “virtual vineyard”. In this digital representation, each grapevine plant marked by RFID can be selected, viewed and edited. Free-to-use software was implemented for use by consumers. 相似文献
6.
库存为线性减函数的随机存贮策略 总被引：1，自引：0，他引：1
以往的存贮策略一般是非随机的允许缺货、不允许缺货及随机的不考虑销售过程贮存费用的存贮策略．本研究在一系列切合实际的假设下,推导出了简明实用的公式及结论,给出了更为合理的存贮策略,是随机存贮策略的拓展． 相似文献
7.
岳晓烔 《山地农业生物学报》2014,(3):46-49
为了研究存放时间对稀有白甲鱼血清样品生化指标检测结果的影响,本研究采用生化试剂盒,对采自贵州清水江的24份稀有白甲鱼血清样品,在-20℃温度下分别保存10天、60天后进行了15个生化指标的测定。结果表明,经过两种存放时间后,在15个生化指标中,稀有白甲鱼血清血红蛋白(Hb)、总胆固醇(TC)、尿素氮(BUN)、总胆红素(TBIL)、谷草转氨酶(GOT)、肌酸激酶(CK)等6个指标的测定值差异显著(P0.05),而总蛋白、白蛋白、葡萄糖、甘油三酯、尿酸、肌酐、谷丙转氨酶、乳酸脱氢酶、碱性磷酸酶等9个指标测定值的差异不明显(P0.05)。可见,不同存放时间对稀有白甲鱼血清样品部分生化指标测定结果有影响。为了保证测定结果的可靠性,对采集的稀有白甲鱼血清样品应立即进行生化指标的测定。 相似文献
8.
二氧化碳的低温储存和运输 总被引：2，自引：0，他引：2
分析了国内使用常温高压气瓶储运ＣＯ２存在的不足，根据国外ＣＯ２低温储运技术，介绍了天然ＣＯ２的低温液化过程和ＣＯ２低温储运的工艺流程，通过分析计算认为，选用Ｓ８－１２．５Ａ单机双级氨制冷压缩机作为主机可满足提供ＣＯ２低温液化所需热量，用ＪＮ－１５１黄河牌汽车底盘、ＣＯ２储罐、仪表箱、增压器及输液软管等改装的低温ＣＯ２罐车，可用于ＣＯ２长途运输。指出采用低温储运ＣＯ２可提高ＣＯ２的充装速度和储运效率 相似文献
9.
不同贮藏温度及时间对包衣种子发芽率的影响 总被引：2，自引：0，他引：2
在常规库存条件下，以玉米、小麦种子及植保型种衣剂为材料，研究了种子包衣后，不同贮藏温度及贮藏时间对其发芽率的影响。结果表明，以1：50药种比包衣后的种子贮存3个月，包衣对种子发芽率无明显影响。包衣后的玉米种子贮存6个月，发芽率比对照降低4个百分点，差异达到显著水平。包衣后的玉米、小麦种子贮存12个月，发芽率比对照下降5个和6个百分点，差异达到极显著水平。进而提出种子包衣的最佳时间为播种前3个月以内；包衣种子贮藏时间不应超过一个种植年度。 相似文献
10.
稻螟赤眼蜂(Trichogramma japonicum Ashmead)是水稻螟虫的优势寄生蜂,为了明确米蛾卵冷藏后对稻螟赤眼蜂繁蜂质量的影响,在0,3,6,10℃4个温度和0,3,6,12,20,25,30,40 d 8个冷藏时间条件下冷藏米蛾卵,调查了稻螟赤眼蜂对冷藏米蛾卵的寄生能力、羽化及性比。结果表明:在4个温度下,稻螟赤眼蜂各指标均随冷藏时间的延长而降低,各温度下,以0℃最为敏感,米蛾卵冷藏至25 d时,稻螟赤眼蜂已不能寄生;其次为3℃,米蛾卵冷藏至25 d时,稻螟赤眼蜂寄生米蛾卵数(0.93粒)、羽化率(21.11%)和性比(0.2♀∶1♂)均显著低于未冷藏米蛾卵。6~10℃冷藏的米蛾卵繁殖稻螟赤眼蜂,各指标下降较缓慢,至12 d时,稻螟赤眼蜂寄生米蛾卵数达22~26粒,寄生后羽化率可82%,雌雄蜂比例可达6.5,显著高于其他温度。综合各指标,工厂化繁殖稻螟赤眼蜂时,米蛾卵最佳冷藏温度为6~10℃,冷藏时间为12 d。 相似文献
11.
12.
城镇化对中国农户储粮影响的区域间差异分析 总被引：1，自引：0，他引：1
以粮食主产区、主销区和产销平衡区为研究区域,建立反映城镇化对农户储粮影响的评价指标体系,该体系选取粮食生产、农村居民粮食消费及农业劳动力3个一级指标、耕地面积等16个二级指标,并以2004年和2011年数据为基础,运用主成分分析方法,研究城镇化对粮食生产三大区域农户储粮影响的差异。结果表明:粮食生产因素对粮食主产区农户储粮有明显影响,而粮食消费及劳动力的就业选择对粮食产销平衡区农户储粮的影响明显,粮食主销区受上述影响较其他两区弱。同时,2004年城镇化对粮食主产区的综合影响最明显,到2011年粮食产销平衡区受到的综合影响最显著。最后,提出了未来中国农户储粮的趋势及相关对策。 相似文献
13.
不同贮藏温度与鲜枣果实中保护酶及脂氧合酶活性变化的关系 总被引：8，自引：0，他引：8
以不同成熟期的冬枣为材料,测定了常温和冷藏条件下鲜枣软化衰老过程中脂氧合酶(LOX),过氧化物酶(POD),过氧化氢酶(CAT)的活性变化。结果表明常温下果实软化衰老加快,3种酶活性较高;在贮藏前期,低温可显著抑制3种酶的活性且在一定程度延迟了衰老。 相似文献
14.
[目的]利用改进的BF-5稀释液（命名为naBF5）,开发一种4℃液态保存猪精子的方法。[方法]把猪精子在LEN、BF5和mBF5这3种稀释液中4℃条件下保存5d,按照保存天数分别检测精子的活力、顶体形态、活率和ATP浓度并进行比较。[结果]在4℃条件下保存的1～2d,精子的活率在3种稀释液中没有显著的差异;但是第3天开始,3种稀释液中的精子活率有显著差异,在mBF5中保存的精子活率显著地高于在LEN和BF5中保存的精子。第1～5天,在mBF5和B巧稀释液中保存的精子正常顶体的百分率高于LEN稀释液中保存的精予;并且,在4℃保存5d后,在mBF5稀释液中保存的精子正常顶体的百分率要高于在BF5中保存的精子。在4℃条件下保存的第1～5天,mBF5稀释液中的精子活力百分率高于LEN和BF5稀释液保存的精子活力。在3种稀释液中,保存的第1～5天,精子活力的百分率都持续地降低。保存的第1～5天,mBF5稀释液中保存的精子ATP浓度比LEN和BF5稀释液中保存的高。保存5d之后3种稀释液中精子ATP浓度都迅速下降。[结论]在4℃条件下保存5d,与LEN和BF5稀释液相比,保存在mBF5稀释液中的精子表现出较高的活力、正常的顶体百分率、活率和ATP浓度。 相似文献
15.
Changes in Enzymatic Activity and Quality Attributes of Late-mature Peaches in Response to Controlled Atmosphere Conditions 总被引：1，自引：0，他引：1
Late-mature peaches (Prunus persica L. Batsch, cv. Dongxuemi ) were stored in air,modification atmosphere (MA) and controlled atmospheres (CA) at 1℃ to investigate enzymatic activities,flesh browning, quality attributes and fruit storability during storage periods. Peaches stored in CA conditions showed significant lower activities of polyphenol oxidase (PPO) and peroxidase (POD) compared to that kept in MA and in air during the early period of storage. CA treatments indicated a better result in maintaining fruit firmness, color and titratable acidity than MA and control treatments. But there was no significant difference in vitamin C and total soluble solids of peaches stored in CA, MA and air. Increasing PPO activity obviously stimulated flesh browning. Peach fruits stored in CA conditions showed a lower activity of POD and higher firmness in the early period of storage. The peaches stored in 5%CO2 + 5%O2 and 10%CO2 + 5%O2 for 92 days had a good quality without any off-flavor. The results indicated CA conditions obviously inhibited the enzymatic browning, delayed senescence and maintained quality of late-mature peaches. 相似文献
16.
温度对南方水蜜桃贮藏生理及货架期品质的影响 总被引：12，自引：0，他引：12
【目的】研究不同温度贮藏模式对南方‘湖景蜜露’水蜜桃贮藏生理及货架期品质的影响，探索适宜的贮藏温度，为南方软质型水蜜桃贮藏技术的发展与应用提供理论指导。【方法】设置不同贮藏温度25℃、5℃、2℃和0℃，测定桃果实贮藏期间的呼吸强度、相对电导率、丙二醛（MDA）、硬度、可溶性固形物（TSS）、总酸以及Vc等各项生理生化指标。【结果】0℃贮藏与25℃、5℃和2℃相比，能较好保持‘湖景蜜露’桃果实整个贮藏期间TSS和TA的含量，显著降低果肉硬度的下降，明显抑制果实贮藏过程中呼吸强度的增加，推迟呼吸峰出现的时间，延缓桃果实膜脂过氧化的发生，果肉未出现糠化等冷害症状，表现出较好的贮藏效果。同时经0℃贮藏28 d出库后，桃果实在常温3 d的货架期内，果肉可以正常软化，食用品质未发生明显劣变。【结论】南方软质型水蜜桃较适宜的贮藏条件为0℃贮藏28 d，出库后放置在20℃条件下货架期约为3d。 相似文献
17.
18.
Insects are major pests of stored grains. In sub Sahara Africa, stored grain insect pests are mainly Coleoptera or Lepidoptera. In the Logone Valley, area covering the Far North Region of Cameroon and South-West of Chad, to our knowledge, the diversity of insect pests noxious to stored products is not established. These beetles and weevils （Insecta：Coleoptera） during their development depreciate food in storage, were able to destroy a whole stock in a very short period of time if no protection of stored food is made. To achieve the diversity of insect pests, inspections of granaries were done in 209 villages of Logone Valley where insect pests were collected and identified. Secondly, the stored grains were sampled in peasant＇s granaries of Logone Valley and reared in incubators in the Unit of Entomological Research of the University of Ngaound6r6. After their emergence, insects were removed, collected and identified. Their noxious efficiency on stored grains is done by the calculation of the density of each insect pests per gram of grains. This study indicates that 12 species of harmful insects attack cereals and leguminous grains in the Logone Valley during storage. The Bruchids were the main insect pests of legumes. Callosobruchus maculatus was the main pest of legume and attacking mainly cowpeas （34.92 bruchids/g of seed） and peanuts （20.75 bruchids/g of seed）. Seven harmful species destroy the cereals. Sitophilus zeamais is the main pest of maize （15.86 weevils/g of maize） and S. oryzae, for sorghum （36.59 weevils/g of maize）. Tribolium castaneum were the main secondary pest. T. castaneum infests both cereals and leguminous. This work summarizes the importance and the diversification of stored grain pests in Logone Valley. Knowing the pest diversity is an important step in the strategy to develop a friendly and ecological control method of these harmful insects. 相似文献
19.
20.
树木营养器官贮藏氮化物性质的研究进展 总被引：2，自引：0，他引：2
分析自20世纪50年代以来关于树木营养器官贮藏氮化物的研究文献资料,归纳其几点性质如下:(1)导管和筛管以外的多年生组织是氮化物的贮藏部位,贮藏氮化物积累在贮藏组织细胞的液泡中;(2)树木有专门的贮藏氮化物;(3)不同类群树木的主要贮藏氮化物的形式具有多样性。 相似文献