InP-based optoelectronic devices for optical fiber communications

In this contribution we report the research and development of 1.55 mu m InGaAsP/InP gain-coupled DFB laser with an improved injection-carrier induced grating and of high performance 1.3 mu m and 1.55 mu m InGaAsP/InP FP and DFB lasers for communications. Long wavelength strained MQW laser diodes with a very low threshold current (7-10 mA) have been fabricated. Low pressure MOVPE technology has been employed for the preparation of the layered structure. A novel gain-coupled DFB laser structure with an improved injection-carrier modulated grating has been proposed and fabricated. The laser structures have been prepared by hybrid growth of MOVPE and LPE techniques and reasonably good characteristics have been achieved for resultant lasers. High performance 1.3 mu m and 1.55 mu m InGaAsP/InP DFB lasers have successfully been developed for CATV and trunk line optical fiber communication.

大面积光纤阵列探测器性能探测单元的进一步测试

对大面积光纤阵列探测器中的光纤阵列探测单元的性能进行检测。测试了不同形状、不同材料的光导以及光导包裹不同反光材料时光纤探测单元的传输效率及时间分辨和位置分辨。确定了大面积光纤探测器探测单元所使用光导的材料和形状,给出了光纤阵列探测器探测单元可达到的时间分辨。

浑太流域洪涝灾害及其治理方略

Hunhe, Taizihe rivers originating from the east mountain areas of Liaoning Province are the biggest tributaries of the left bank of Liaohe River. From the initial stage of New China to the early 1990s, the frequency of flood damage had decreased, but recently the disasters have upgraded and changed from trunk stream to tributary basins. In July 1995, Dongzhouhe, a tributary of Hunhe River, suffered from a heaviest flood since establishing the document of floods in Hunhe basin. Meanwhile, a peak discharge, almost beyond double defending ability, occurred at Dadongshanpu Station of Beishahe River, a tributary of Taizihe River. Besides the continued heavy rainstorm, no controllable water conservancy projects and ecological damages caused by quickly decreasing forest cover and water and soil loss are the two main causes of flood damage. In addition, the low flood protection standard is also one of causes. According to the above analyses, some strategies of synthetic controlling for flood damages were put forward: 1) Establishing the system of ecological engineering to defend floods and reduce disasters; 2)Setting up storage and detention areas; 3) Establishing flood controlling information system; 4) Improving the accuracy of media short period and short period rainstorm forecast and flood forecast; 5) Insurance of flood protection.

几种酸性土壤供氮力测定方法的综合评价

模拟旱地条件进行黑麦草盆栽试验,对不同供氮力指标与黑麦草吸氮量相关性进行研究,结果表明,短期好气培养法测定的可矿化氮与吸氮量相关系数为0.820;氯化钾与氯化钙浸提的硝态氮与黑麦草吸氮量的相关系数分别为0.892和0.916,表明硝态氮含量作为土壤供氮能力指标具有一定的稳定性;微生物量氮的测定结果不够稳定且与黑麦草吸氮量相关性不高(r=0.751)。分析表明,氯仿熏蒸-浸提全氮与吸氮量的相关性最好,相关系数可达0.941,是一个较好的供氮力指标。

黄土高原野生蔬菜资源与开发利用

略述黄土高原野生蔬菜的主要种类和分布 ,分析了野生蔬菜的营养价值 ,医疗保健作用和市场前景 ,提出开发利用的途径、措施和应注意的问题

轮作和施肥对半干旱区作物地上部生物量与土壤有机碳的影响

了解轮作与施肥对土壤有机碳的影响是建立持续发展措施的关键。【方法】以长期定位试验(1984～2002)中的10个典型处理为基础,分析了地上部生物量和耕层(0～20cm)土壤有机碳变化,探讨半干旱区轮作和施肥对0～20cm土层有机碳的影响,10个典型处理分别为休闲(F);冬小麦连作体系中的3个施肥处理:不施肥(W/W+CK)、化肥(W/W+NP)、化肥有机肥(W/W+NP-FYM);冬小麦-冬小麦+糜子-豌豆轮作体系中的3个施肥处理:不施肥(W/WM/P+CK)、化肥(W/WM/P+NP)、化肥有机肥(W/WM/P+NP-FYM)处理;1个冬小麦—冬小麦-红豆草轮作处理(W/W/S+NP);人工苜蓿中2个施肥处理:不施肥(A/A+CK)和化肥有机肥处理(A/A+NP-FYM)。【结果】冬小麦连作体系(W/W)中,不施肥处理(W/W+CK)的地上部生物量平均为3.3t·ha-1,化肥处理(W/W+NP)和化肥有机肥处理(W/W+NP-FYM)依次为7.5和11.2t·ha-1;冬小麦-冬小麦+糜子-豌豆轮作(W/WM/P)体系中,不施肥处理(W/WM/P+CK)地上部生物量平均3.1t·ha-1,W/WM...

四种园林植物的热值与养分特征

测定了蔷薇科植物美人梅、樱花和木兰科植物白玉兰、广玉兰不同组分的热值、养分和灰分含量,探讨4种植物不同发育阶段根系、枝干和叶等器官的热值分配特征及其影响因子.结果表明:4种植物不同组分干质量热值和去灰分热值在17.02~21.93 kJ.g-1和18.42~22.57 kJ.g-1之间;叶片和细根具有较高的干质量热值和去灰分热值,去灰分热值随着根系和茎干(枝)的发育呈减小趋势.美人梅和樱花的干质量热值和去灰分热值总体上高于白玉兰和广玉兰.细根干质量热值和去灰分热值与其养分和灰分含量呈极显著相关(P<0.01).随着根系的发育,干质量热值和去灰分热值与有机碳含量的相关性逐渐降低,不同器官干质量热值与全氮含量相关性最强.

Estimation of wind erosion rates by using Cs-137 tracing technique: A case study in Tariat-Xilin Gol transect, Mongolian Plateau

Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we established the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the Cs-137 tracing technique and examined their spatial dynamics. Our results showed that the Cs-137 inventories of sampling sites ranged from 265.63 +/- 44.91 to 1279.54 +/- 166.53 Bq.m(-2), and the wind erosion rates varied from 64.58 to 419.63 t.km(-2).a(-1) accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.

Synergistic extraction of zinc(II) by mixtures of primary amine N1923 and Cyanex272

The extraction of zinc(II) and cadmium(II) from chloride solution by mixtures of primary amine N1923 and Cyanex272 (HA) was studied. The synergistic effect was observed for the extraction of zinc(II) while no synergistic effect for cadmium(II), which makes it possible to separate zine(II) and cadmium(II) with the mixtures. The results showed that zinc(II) was extracted as (RNH3Cl)(3) . ZnCIA instead of ZnA(2) . 2HA which was extracted by Cyanex272 alone. The extraction mechanism was discussed and the formation constants and thermodynamic functions were determined. The separation factors between zinc(II) and cadmium(II) were calculated.

Investigation of covalency and spectrum shifts in 3d transition-metal compounds

By using a correction factor of d electron effects on bond, PV theory is applied to the calculation of chemical bond;parameters of d transition-metal compounds. Racah parameters and Mossbauer isomer shifts are calculated, and the results are agreement with the experimental values.

3d过渡晶体化学键共价性和光谱位移研究

本文利用 ＰＶ理论通过考虑 ３ ｄ电子对晶体化学键的影响，计算了若干 ３ ｄ过渡金属化合物的化学键参数并运用于Ｒａｃａｈ参数和穆斯堡尔谱同质异能位移的研究，计算得到的结果与实验值符合的很好。