中能Abrasion-Ablation模型的核内核子密度分布修正

将具体的核内核子 (包括中子、质子 )密度分布引入到中能Abrasion -Ab lation模型中 ,用修正后的模型计算了 30MeV/u　 4 0 Ar +natAg反应中的弹核碎裂过程 .结果表明 ,在非常周边的碰撞中 ,修正后的模型计算的碎片截面与修正前的计算相比有明显的差别 ,反映了核密度边缘弥散的影响 .与实验结果的比较验证了中能弹核碎裂碎片能量相对于束流能量的降低是由摩擦作用引起的 .

Gravitational corrections to energy-levels of a hydrogen atom

The first-order perturbations of the energy levels of a hydrogen atom in central internal gravitational field are investigated. The internal gravitational field is produced by the mass of the atomic nucleus. The energy shifts are calculated for the relativistic 1S, 2S, 2P, 3S, 3P, 3D, 4S, and 4P levels with Schwarzschild metric. The calculated results show that the gravitational corrections are sensitive to the total angular momentum quantum number.

黑龙江大兴安岭地区森林害虫发生面积与气象因子的关系

对黑龙江大兴安岭地区6个气象台站的气象资料进行整理和分析,从中筛选出影响虫害发生面积的7个气象因子,并分别对其做相关分析,研究了气象因子对种群数量的影响,模拟虫害发生面积预测方程。结果表明:与虫害发生面积密切相关的因子有年积温(≥10℃)、年降水量和干燥度;虫害发生面积同三者的Pearson相关系数分别为0.701、-0.814和0.937;通过分析极端气候现象对虫害面积的影响,发现春季阴雨和虫害面积存在显著的正相关关系,冬冻和春寒对虫害发生面积并没有直接的影响。

黄土塬区三种豆科牧草的竞争生长

通过田间试验研究了沙打旺、紫花苜蓿和达乌里胡枝子3种豆科牧草在黄土旱塬以不同密度单播、混播时的竞争生长能力及水分利用效率。单播时苜蓿生长次年3个密度的生产力分别为15349kg·hm-2、20582kg·hm-2、21531kg·hm-2,沙打旺和胡枝子3个密度的生产力分别为7979kg·hm-2、16 440 kg·hm-2、21055kg·hm-2和2412kg·hm-2、5270kg·hm-2、7102kg·hm-2。混播草地生产力以苜蓿+胡枝子最高(平均19227kg·hm-2),沙打旺与胡枝子混播的生产力最低(平均11977kg·hm-2)。和生产力较高的参混种苜蓿、沙打旺单播相比,苜蓿与沙打旺混播及沙打旺与胡枝子混播的生产力在3种密度下均有不同程度的降低。苜蓿主根下扎深度2m,0~60cm根系占总根量的66%,沙打旺和胡枝子根系最大下扎深度分别为1.8 m和1.5m,0~60cm根系占总根量比例分别是80%、91%。3种牧草中苜蓿的平均水分利用效率最高,为25.75kg·mm-1·hm-2,胡枝子最低为7.71kg·mm-1·hm-2,沙打旺居中。苜蓿群体种内个体间竞争强度高于沙打旺和胡枝子。结果...

中国北方半干旱区机械化坐水种技术研究

机械化坐水种已成为中国半干旱区作物抗旱播种的有效措施。本文探讨了机械化坐水种的技术原理,研究了作物出苗的适宜土壤底墒,分析了2BQMS-2型坐水播种机的性能优点,提出了应用机械化坐水种技术需要解决的问题,为中国北方半干旱区发展机械化坐水种提供技术依据。

包裹法对民用高氟石煤氟硫污染的防治作用

提出了用钙基固氟剂包裹石煤以降低氟硫污染的方法.8户使用包裹钙基固氟剂石煤的农家和8户使用普通石煤的农家的比较结果表明,包裹固氟剂石煤组比普通石煤组燃煤氟释放率平均降低了44.7%(P<0.05);室内空气氟含量下降了85.7%(P<0.01);室内空气SO2含量降低了75%(P<0.05).放置条件较一致的4个玉米、辣椒样品氟含量的比较表明,使用包裹固氟剂石煤农户家的玉米、辣椒样品的氟含量分别比使用普通石煤的下降了50%和53%.

Poly(oligothiophene-alt-benzothiadiazole)s: Tuning the Structures of Oligothlophene Units toward High-Mobility "Black" Conjugated Polymers

A series of donor-acceptor low-bandgap conjugated polymers, i.e., PTnBT (n = 2-6), composed of alternating oligothiophene (OTh) and 2,1,3-benzothiadiazole (BT) units were synthesized by Stille cross-coupling polymerization. The number of thiophene rings in OTh units, that is n, was tuned from 2 to 6. All these polymers display two absorption bands in both solutions and films with absorption maxima depending on n. From solution to film, absorption spectra of the polymers exhibit a noticeable red shift. Both high- and low-energy absorption bands or P'F5BT and PT6BT films locate in the visible region, which are at 468 and 662 nm for PT5BT and 494 and 657 nm for PT6BT.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor(单掺杂与共掺杂离子对Sr_2Mg(BO_3)_2磷光体热释发光的影响)

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.