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Schaefer VJ 《Science (New York, N.Y.)》1966,154(3756):1555-1557
When exposed to a trace of iodine vapor, the submicroscopic particles of lead exhausted by automobiles produce nuclei for the formation of ice crystals. Concentrations of particles exceeding 10(6) per liter can be directly sampled from the exhaust pipe of an idling motor. Concentrations of from 10(4) to 10(5) per liter have been found in rural air downwind of auto roads; the concentration at one rural site has increased by an order of magnitude in 13 years. The phenomenon may provide a method of modifying clouds, and of determining ( and monitoring) the percentage of automobile exhaust in a polluted atmosphere. It may be an important factor in inadvertent modification by man of the climate. 相似文献
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湿地松家系产脂力、树脂密度和松节油含量的测定与遗传分析 总被引:5,自引:1,他引:4
为了精确测定湿地松产脂力、树脂密度和松节油含量,研究其遗传变异规律,选择产脂性状优良的湿地松遗传材料,利用一套改良的松脂测试收集器和水蒸气蒸馏装置,对49个湿地松自由授粉家系进行了测定分析。结果表明:方差分析显示湿地松产脂力、胸径和松脂基本密度的家系效应均极显著(P0.01),家系遗传力分别为0.798、0.436、0.337,单株遗传力分别为0.685、0.368、0.295,分别处于较高水平;相关分析表明,产脂力与松脂基本密度之间极显著正相关(r=0.540, P0.01),而松脂中松节油含量与松脂基本密度呈极显著负相关(r=-0.838, P0.01);松脂中松节油含量是评价松脂质量的一个重要指标,通过产脂力与松节油含量的乘积即松节油产量指数估算各个参试家系松节油含量指标的选择差、现实增益和遗传增益,筛选出显著优于对照的4个优良家系。 相似文献
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Traces of iodine in test samples of irradiated photochemical smog atmospheres either inhibit ozone formation or lower its concentration. Eye and respiratory irritation are reduced qualitatively. Iodine is more effective in suppressing ozone in a photochemical smog atmosphere than it is in purified air. 相似文献
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2009年7月8~13日湖北省西北部出现了一次罕见的盛夏阴雨天气过程中局地暴雨天气,分析探讨了该过程的环流形势及动力、热力和水汽等对这次强降水的贡献。结果表明,巴尔克斯湖冷涡带来的冷空气是局地暴雨的触发机制,贝加尔湖低压为东亚环流调整提供了外来动力,暴雨发生时散度场在高空辐散具有强烈"抽吸作用",孟加拉湾暖湿气流和南海暖湿空气是暴雨的水汽源,暴雨落区出现在能量锋区前部、高能舌顶端轴线偏向冷空气一侧,Q矢量散度、水汽螺旋度负值区对于局地暴雨的短期预报有重要的指示作用。 相似文献
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为明确松节油对米尔贝霉素的增效活性和稳定性, 采用叶碟喷雾法, 分别测定了以松节油和乙醇为溶剂配制的米尔贝霉素乳油对朱砂叶螨Tetranychus cinnabarinus的毒力, 半致死质量浓度(CL50)分别为0.031 4, 0.139 0 mg·L-1, 共毒系数为442.68, 表现出显著的增效活性。光解试验表明, 以松节油为溶剂能够提高米尔贝霉素的稳定性。气相色谱-质谱联用仪(GC-MS)分析, 松节油中α-蒎烯、莰烯、(R)-苧烯、3-蒈烯等萜烯类物质总含量超过60%, 萜烯类物质对昆虫表皮具有良好的渗透作用, 是其增效作用的主要原因。松节油可作为溶剂和增效剂用于米尔贝霉素绿色乳油制剂加工。 相似文献
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Particulate air pollution has been shown to strongly suppress precipitation from convective clouds over land. New observations show that precipitation from similar polluted clouds over oceans is much less affected, because large sea salt nuclei override the precipitation suppression effect of the large number of small pollution nuclei. Raindrops initiated by the sea salt grow by collecting small cloud droplets that form on the pollution particles, thereby cleansing the air. Therefore, sea salt helps cleanse the atmosphere of the air pollution via cloud processes. This implies that over oceans, the climatic aerosol indirect effects are significantly smaller than current estimates. 相似文献
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厘清饱和水汽压差(VPD)的年际动态特征有助于深入理解大气干湿程度对气候变化的响应。本研究基于我国西南地区105个台站1982—2015年的气象观测资料,利用Mann-Kendall突变检验分析VPD的突变特征,基于统计分析探讨突变点前后的VPD变化趋势及影响因素。研究结果表明,西南地区1982—2015年VPD变化以2000年为突变年,增速由0.001 kPa/a变为0.005 kPa/a,并且VPD呈增加趋势的站点在2000年后增多。VPD在时间动态上出现变化的主要原因是在2000—2015年间相对湿度下降幅度增加,导致西南地区出现更干燥的气候特征。作为大气主要水汽来源的外来水汽通量和局地实际蒸散发在2000年后表现为增长趋势,但由于2000年后更高的空气温度引起饱和水汽压比实际水汽压增幅更大,即大气中实际水汽增加远低于饱和水汽容量增加,进而导致VPD增幅更大。本研究表明在突变点后西南地区VPD显著变化的原因主要是温度上升对相对湿度的影响,研究结果有助于深入理解中国西南地区的气候变化,明晰VPD变化背后的相关机制,为该地区的生态系统构建和未来气候变化应对提供参考。 相似文献
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To study the possibility of using turpentine oil and other turpentines as adjuvants, the effects of aqueous lyosols of turpentine oil on the erythrocyte distribution by osmotic resistance were analyzed. In our study, differential osmoerythrograms obtained by modifying the Idelson’s approach to the erythrocyte osmotic resistance measurement were utilized. It was found that, when turpentine oil content in the lyosol was insufficient for direct hemolysis, four concentration zones with corresponding effects can be distinguished: I—<0.014 g/L; II—0.014–0.1 g/L; III—0.11–0.14 g/L; IV—>0.14 g/L. It was assumed that the detected effect will allow controlling the intravascular hemolysis when using terpenoids as adjuvants. 相似文献
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The adsorption of iodine on platinum single crystals was studied with the scanning tunneling microscope (STM) to define the limits of resolution that can be obtained while imaging in air and to set a target resolution for STM imaging of metal surfaces immersed in an electrochemical cell. Two iodine adlattice unit cells of slightly different iodine packing density were clearly imaged: ( radical7 x radical7) R19.1 degrees -I, surface coverage ?(I) = 3/7; and (3 x 3)-I, ?(I) = 4/9. The three iodine atoms in the ( radical7 x radical7) unit cell form a regular hexagonal lattice interatomic distance d(I) = 0.424 nanometer, with two atoms adsorbed in threefold hollow sites and one atom adsorbed at an atop site. The (3 x 3) unit cell showed two different packing arrangements of the four iodine atoms exit. In one of the (3 x 3) structures, the iodine atoms pack to form a hexagonal lattice, d(I) = 0.417 nanometer, with three of the iodine atoms at twofold adsorption sites and one atom at an atop site. Another packing arrangement of iodine into the (3 x 3) unit cell was imaged in which the iodine atoms are not arranged symmetrically. 相似文献
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呼和浩特市春季气象要素与空气质量指数的灰色关联分析 总被引:1,自引:0,他引:1
利用环保部门互联网公布的呼和浩特市2014年春季(3-5月)空气质量指数,及气象部门同步观测的有关气象要素数据,采用灰色关联方法分析探讨日平均风速、日平均地面温度、日平均水汽压、日平均气温、日平均相对湿度对呼和浩特市春季空气质量指数影响程度,从而为进一步做好空气污染气象条件预报及空气质量预报提供依据。结果表明,呼和浩特市2014年春季,各气象因素对空气质量指数影响程度从大到小排序依次为日平均风速、日平均相对湿度、日平均水汽压、日平均气温、日平均地面温度。 相似文献
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利用L9(34)正交试验设计,以松节油的包合率及包合物产率为考察指标进行综合评分,研究饱和水溶液法制备松节油-β-环糊精包合物的最佳工艺,并采用显微镜法、热稳定性试验、薄层色谱法(TLC),红外光谱法(IR),气质联用(GC-MS)等对松节油-β-环糊精的包合效果进行评价.结果表明:饱和水溶液法制备松节油β-环糊精的最佳包合工艺为松节油∶β-环糊精为1∶8(mL∶g),包合时间2.5h,包合温度60℃;包合物形成一种新的物相,且包合前后松节油的化学组成基本不变;该工艺简单、稳定,所得包合物产率和包合率较高. 相似文献
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由于拱顶油罐的罐顶与罐壁设计为弱连接,在蒸汽吹扫作业中,易发生罐顶爆裂事故,分别从拱顶油罐的设计规定和受力状况两方面进行了分析,分析结果表明,预防拱顶油罐罐顶爆裂的关键是确定吹扫作业时间,提出采取严格控制扫线作业时间和扫线蒸汽流量,增大油气空间的体积和增加罐顶通气孔数量和面积等措施,可有效地预防该类事故的发生。 相似文献
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The cytotoxic in vitro effect of water turpentine oil liozols, intended as adjuvants for a number of vaccines, is investigated by the acid erythrogram method. It is found out that the acid resistance of erythrocytes does not change at a turpentine oil concentration below 0.0013 g/L in liozol and increases at a concentration of 0.0013–0.0125 g/L. If the concentration continues to increase, however, the acid resistance of erythrocytes decreases to reach the value of EC50 at a concentration of 0.1–0.125 g/L; then follows the zone of direct hemolytic action of liozol. 相似文献
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Concentrations of cloud condensation nuclei measured along the East Coast from Virginia to Long Island ranged from 1000 to 3500 per cubic centimeter as compared to 100 per cubic centimeter in clean maritime air and 300 per cubic centimeter in continental air. The global anthropogenic production rate of cloud condensation nuclei may be comparable to the natural production rate; in some industrial areas cloud condensation nuclei are dominated by anthropogenic sources. 相似文献
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利用NECP1°×1°的再分析资料、常规气象资料对2010年4月21~22日广东省的暴雨过程进行分析。结果表明,此次过程是青藏高原不断有槽下滑影响广东,850hPa切变线西南气流提供强大水汽输送的环流背景下,受地面冷空气触发而产生。冷空气南下过程受南岭山脉阻挡,导致西南地区冷平流从两广交界地区进入广东,影响广东中部地区,导致这些地区的能量和水汽释放,造成强降水。冷空气向θse高值区渗透过程中,不稳定能量迅速被释放,触发强对流天气的发生,正好对应地面强降水位置。 相似文献
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C Pöhlker KT Wiedemann B Sinha M Shiraiwa SS Gunthe M Smith H Su P Artaxo Q Chen Y Cheng W Elbert MK Gilles AL Kilcoyne RC Moffet M Weigand ST Martin U Pöschl MO Andreae 《Science (New York, N.Y.)》2012,337(6098):1075-1078
The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest. 相似文献
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Ozone uptake by bean leaves 总被引:4,自引:0,他引:4
The removal of ozone from the air by bean leaves is regulated by the same factors that control the exchange of water vapor between leaves and the atmosphere. 相似文献