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冬春大棚蔬菜,极容易患猝倒病和立枯病两大病害。番茄、茄子、 辣椒、瓜类 等,在苗床期 和生长期患 病后都可造 成较缺苗或 幼苗成片死 亡。为保证大 棚蔬菜的早 熟和稳产、高 产,必须重视 搞好两大病 害的防治。 相似文献
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谢钢 《江苏大学学报(自然科学版)》1994,(5)
在1989年进行的“实习心理调适与强化”的课题研究基础上,以实际调查数据为根据,运用心理学理论,结合多年的工作经验,分析了如何从心理调适着手,强化实习效果的问题,并提出了一些建设性意见。 相似文献
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1初中课程中的螺线管磁场及其演示实验
1979年人民教育出版社出版了文革以后的第一套全国统编教材,书中安排了如图1所示的演示实验.书中的文字说明是:“如图5—27(图5—27是教科书插图编号——笔者)所示,给螺线管通电,铁块受到螺线管的吸引使弹簧伸长.调节变阻器,改变通过螺线管的电流强度,可以看到电流越强,弹簧被拉伸得越长.这表明通过螺线管的电流越强它的磁性也越强.如果换用匝数不同的螺线管而保持通过螺线管的电流强度跟前面的实验一样, 相似文献
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Treatment of hydrate rare-earth(RE=La,Pr,Nd,Sm-Lu)chloride with ammonium pyrrolidinyldithiocarboxy-late(apdtc)and 1,10-phenanthroline(phen)gave rise to thirteen complexes with an empirical formulaRE[(pdtc)_3(phen)].The enthalpies of solution of hydrate rare-earth(RE= Sm-Ho,Tm-Lu)chloride,apdtc and phenin ethanol were measured by an RD-496 Ⅲ microcalorimeter at 298.15 K,along with the mixing enthalpy of etha-nol solution of APDC and that of phen and the enthalpies of reaction of formation of the title complexes in ethanol.The enthalpies of reaction of formation of the title complexes in solid were available through a rationally thermo-chemical cycle.Using an RD-496 Ⅲ microcalorimeter,a model was developed for calculating the specific heat ca-pacity and the responding specific heat capacity of the complexes were determined.The thermochemical properties,including the enthalpies of solution of hydrate rare earth chloride in ethanol,the enthalpies of reaction of formationof the title complexes in ethanol,the enthalpies of reaction of formation of the title complexes in solid,the specialheat capacities at room temperature,the standard molar enthalpies of combustion and the standard molar enthalpiesof formation for this series of complexes versus the atomic numbers of rare earth,presented triplet effect,which isrepresentative of certain covalent bond between RE and the ligands and the result of 4f electron not shielded fullyby 5s5p. 相似文献
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A ternary solid complex Lu(Et2dtc)3(phen) has been obtained from the reaction of hydrated lutetium chloride with sodium diethyldithiocarbamate
(NaEt2dtc), and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol. IR spectrum of the complex indicates that
Lu3+ binds with sulfur atom in the Na(Et2dtc)3 and nitrogen atom in the o-phen. The enthalpy change of liquid-phase reaction of formation of the complex,
ΔrHmӨ (l), was determined to be (-32.821 ± 0.147 ) kJ·mol-1 at 298.15 K by an RD-496 Ⅲ type heat conduction microcalormeter. The enthalpy change of the solid-phase reaction of formation of the complex,
ΔrHmӨ (s), was calculated to be (104.160 ± 0.168) kJ ·
mol-1 on the basis of an appropriate thermochemistry cycle. The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, such as the activation enthalpy (ΔH≠Ө), the activation entropy (ΔS≠Ө), the activation free energy (ΔG≠Ө), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained by combination the reaction thermodynamic and kinetic equations with the data of thermokinetic experiments. The molar heat capacity of the complex,
cm, was determined to be (82.23 ± 1.47) J·mol-1·K-1 by the same microcalormeter. The constant-volume combustion energy of the complex, ΔcU, was determined as (-17 898.228 ± 8.59) kJ·mol-1 by an RBC-Ⅱtype rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion,
ΔcHmӨ, and standard enthalpy of formation, ΔfHmӨ, were calculated to be (-17 917.43 ± 8.11) kJ·mol-1 and (-859.95 ±10.12) kJ·mol-1, respectively. 相似文献
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