不同培肥措施下种植制度及撂荒对土壤微生物量碳氮的影响

以黄土高原南部半湿润易旱区已进行17年的田间定位试验为研究对象,研究了不同培肥措施(不施肥、施用氮磷钾及氮磷钾与有机肥配合施用)下两种种植制度(一年1熟及一年两熟)和撂荒对土壤微生物量碳、氮(SMBC、SMBN)及可溶性有机碳、氮(SOC、SON)等含量的影响。结果表明,与一年1熟的小麦-休闲种植制度相比,一年两熟小麦-玉米轮作提高了0~10cm土层SMBC、SMBN、有机碳(TOC)、全氮(TN)和土壤SOC、SON的含量,而对10~20cm土层上述测定指标影响不大。与不施肥(CK)或单施化肥处理(NPK)下小麦-休闲和小麦-玉米轮作方式相比,撂荒处理显著提高了0~10cm土层各测定指标的含量。不同培肥措施相比,氮磷钾配施有机肥显著提高了0~10cm、10~20cm土层SMBC、SMBN含量;NPK处理0~10cm土层SMBN含量显著增加,10~20cm土层SMBN和0~10cm、10~20cm土层SMBC含量增加但未达显著水平。不同培肥措施和种植制度对SMBC/TOC和SMBN/TN的比例无明显影响。

无规支化高聚物溶液标度规则的研究

研究分化结构对标度律的影响，具有重要的理论意义。1. 支化物的合成与表征 通过苯乙烯（ST）和少量二乙烯基本（DVB）共聚，制得了几个四官能度分化聚苯乙烯（BpS）样品。利用GpC数据和[η]值，用电子计算机试误法拟合粘度曲线，确定了四官能度支化聚苯乙烯的分子量和支化参数。2. 只通过线型和无规分化聚苯乙烯的lyM-Ve曲线的斜率求得了回转半径与聚合度关系R_b ～ N~(ν_b)中的标度指数ν_b = 0.459，与计算和结果相符合。（本实验中得到ν_t = 0.553）。3. 用光子相关光谱研究了支化结构对扩散解为的影响。无规支化聚苯乙烯分子在环已烷中扩散（稀溶液范围）与浓度和温度有关，发现支化对浓度系数kd有影响，kd = 0时的温度Tc（这一温度是高分子链从θ条件下的无扰状态向良溶剂中链完全伸展状态过渡的临界温度）由于分子的支化而升高，扩散系数具有处复的浓度依赖关系（55 ℃时B4-2的kd = 0）。4. 支化对细结的影响 用粘度法测定了LpS和BpS样品在25 ℃THF中的临界结浓度C_E~*，在我们测定的分子量范围内，无论LpS还是BpS的临界细结浓度C_E~*都与C_E~* ～ N~(1-3ν)标度关系存在偏离，这是由于未考虑排除体积效应（与分子量有关）造成的。从上看出，支化分子的标度规则与线型分子的存在明显差别，而且在不同的浓度原，长支链的存在（结构因素）和由于支化使分子尺寸变小对溶液性质具有不同的影响。

A NEW RESULT IN TRANSIENT CURRENT EXPERIMENT ON A-SI-H P/I/N AND N/I/N DEVICES

The transient current response of a-Si:H in both p/i/n and n/i/n structures has been measured as a function of pulse intermittence and pulse amplitude. The results are consistent with the picture that in p/i/n samples the peculiar current response is caused by the competing contributions of electrons and holes which show themselves in different time scales.

GaAs吸收衬底生长的立方相GaN发光二极管的工艺设计与实现

利用光学薄膜原理，计算了采用晶片键合技术来提高以GaAs为衬底的立方相GaN的出光效率的理论可行性，以Ni为粘附层，Ag为反射层的Ni/Ag/Au薄膜体系可以使立方GaN的出光效率从理论上提高2.65倍左右。实验结果证实，利用键合方法实现的以Ni/Ag/Au作为反射膜的样品的光反射率比未做键合的GaN/GaAs样品的光反射率的理论计算的459.2nm处提高了2.4倍。

Spotsize Converter Integrated DFB Laser Diode Using Selective Area Growth of MOCVD

The characteristics of thickness enhancement factor and bandgap wavelength of selectively grown In-GaAsP are investigated. A high thickness enhancement factor of 2.9 is obtained. Spotsize converter integrated DFB lasers are fabricated by using the technique of SAG. The threshold current is as low as 10.8mA. The output power is 10m W at 60mA without coating and the SMSR is 35.8dB. The vertical far field angle (FWHM) is decreased from 34 °to 9 °. The tolerance of 1dBm misalignment is 3.4μm vertically.

Design of high brightness cubic-GaN LEDs grown on GaAs substrate

The Principle of optical thin film was used to calculate the feasibility of improving the light extraction efficiency of GaN/GaAs optical devices by wafer-bonding technique. The calculated results show that the light extraction efficiency of bonded samples can be improved by 2.66 times than the as-grown GaN/GaAs samples when a thin Ni layer was used as adhesive layer and Ag layer as reflective layer. Full reflectance spectrum comparison shows that reflectivity for the incident light of 459.2 nm of the bonded samples was improved by 2.4 times than the as-grown samples, which is consistent with the calculated results.