栽培和施肥模式对黄土区旱地土壤微生物量及可溶性有机碳、氮的影响

以黄土高原南部地区的两个定位试验为基础,研究了旱地不同栽培和施肥模式对土壤微生物量碳、氮和可溶性有机碳、氮的影响。结果表明,秸秆覆盖显著提高土壤微生物量氮(SMBN)含量,地膜覆盖使SMBN含量显著降低;秸秆和地膜覆盖显著降低小麦拔节期和灌浆期土壤可溶性有机氮(SON)含量。适量施用化学氮肥(120kg/hm2)有利于小麦生长后期SMBN含量的升高,而过量施用(240 kg/hm2)显著降低SMBN含量。与不施肥处理相比,土地经长期撂荒后0-10 cm土层SMBC,SMBN,SOC和SON含量显著提高;氮磷钾配施有机肥显著提高小麦各生育期0-10,10-20 cm土层SMBC,SMBN,SOC和SON的含量;单施氮磷钾肥对土壤SMBC,SMBN含量无明显影响,提高土壤SOC,SON的平均含量。土壤SMBC,SMBN,SOC和SON含量两两之间呈极显著正相关关系,四者含量与土壤有机碳、全氮含量间的正相关关系也达显著或极显著水平。

NaCl胁迫对甜高粱幼苗保护酶活性等生理特性的影响

采用不同浓度NaCl溶液(100 mmol/L、200 mmol/L)胁迫处理甜高粱幼苗,测定了叶片中叶绿素含量、脯氨酸含量及三种保护酶活性等生理指标。结果表明:100 mmol/L和200 mmol/L处理的甜高粱幼苗质膜相对透性、脯氨酸和丙二醛含量升高;可溶性蛋白和叶绿素含量降低;保护酶系统中叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均升高,且在100 mmol/L浓度处理下达到最大,而过氧化物酶(POD)活性呈先升高再降低趋势。NaCl胁迫对甜高粱幼苗的一些生理特性产生一定影响。

拉米呋淀及其衍生物的合成和药效评估

（1）研究了专利中报道的以2-苯甲酰氧甲基5-乙氧基-1，3氧硫杂环戊烷为中间体，在不同的Lewis酸催化下与乙酰化的胞嘧啶的C-N键偶联反应。研究结果发现，反应的最终产物为苯甲酸2-乙氧基-2-（N_4'-乙酰基胞嘧啶-1'-基）-乙酯。依据实验结果，我们提出了硅甲基化的乙酰基胞嘧啶首先进攻氧硫杂环中间体时，烷硫基比乙氧基基团更易离去，从而进攻氧硫杂环中间体的C-2位而非C-5位的反应机理。（2）研究了不同的Lewis酸催化剂对以2-苯甲酰氧甲基-5-乙酰氧基-1，3-氧硫杂环戊烷中间体与乙酰化胞嘧啶的C-N键形成反庆的影响。结果显示，由于催化剂SnCl_4与氧硫环的硫原子螯合，从而导致胞嘧啶的氮原子从氧硫环的β面进攻，产生顺反产物的比值为3：1，是合成顺式产物的最好催化剂。（3）设计了四步反应合成2-羟甲基-5-（胞嘧啶-1'-基）-1，3-氧硫杂环戊烷（cis-BCH-189）的路线：通过苯甲酰氧基乙醛与2，5-二羟基-1，4-二噻烷的羟醛缩合反应构筑1，3-氧硫杂环戊烷，经乙酰化反应及SnCl_4催化下的C-N键形成反应接上乙酰化胞嘧啶，最后在K_2CO_3/MeOH体系中脱去保护基，得到主产物cis-BCH-189。利用该方法合成外消旋的cis-BCH-189，未见文献报道。其优点在于原料便宜易得，产品收率高，操作简单，是大量合成cis-BCH-189的有效方法。（4）设计了如下合成2-羟甲基-4-（胞嘧啶-1'-基）-1，3-氧硫杂环戊烷的路线：以苯甲酰氧基乙醛和巯基乙醇为原料，在甲苯溶剂中和p-TsOH催化下，经羟醛缩和反应合成得到2-苯甲酰氧基-1，3-氧硫杂环戊烷，然后经间氯过苯甲酸（m-CPBA）氧化为亚砜，在NaOAc/Ac_2O中回流发生普梅雷尔重排反应，得到2-苯甲酰氧甲基-4-乙酰氧基-1，3-氧硫杂环戊烷中间体，以Lewis酸SnCl_4为催化剂，获得顺反比值为2：1的产物。将顺式产物在K_2CO_3/MeOH体系中脱去保护基，得到外消旋的顺式-2-羟甲基-4-（胞嘧啶-1'-基）-1，3-氧硫杂环戊烷。反应共五步，总产率为11%，合成路线未见文献报道。此合成路线原料使宜易得，操作简单，是合成大量产品的有效途径。（5）分另研究了以（-）-樟脑酰氯和（+）-（艹孟）氧基甲酰氯为手性拆分试剂时cis-BCH-189的拆分效果，结果显示前者几乎对其没有拆分能力，而后者却是非常好的拆分试剂。拆分过程为（+）-（艹孟）氧基甲酰氯与顺式-2-羟甲基-5-（N_4'-乙酰基胞嘧啶-1'-基）-1，3-氧硫杂环戊烷经化学反应成酯后，于0 ℃在甲醇溶剂中重结晶，得到左旋光异构体，经K_2CO_3/MeOH体系酯解脱保护基后，得以拉米呋啶纯品，旋光度为[α]_D~(20) = -137°(c0.01, MeOH)；母液浓缩析出的固体经脱保护基后可得到右旋光的对映体，旋光度为[α]_D~(20) = +34.03°(c0.01, MeOH)。（6）探索了以Hg(CN)_2、HgBr_2银盐及TMSOTf等为催化剂的反应条件下，溴代半乳糖四乙酸酯及β-D-半乳糖五乙酸酯分别与顺式-2-羟甲基-5-（N_4'-乙酰基胞嘧啶-1'-基）-1，3-氧硫杂环戊烷的糖苷键形成反应。结果发现以Lewis酸TMSOTf为催化剂时，以β-D-半乳糖五乙酸酯为反应原料获得的BCH-189的糖苷衍生物的产率最高；而在汞催化下，以溴代半乳糖四乙酸酯为反应原料获得的BCH-189的糖苷衍生物的产率仅为10～ 20%。以TMSOTf为催化剂，将拉米呋定、顺反BCH-189及顺式2-羟甲基-4-（胞嘧啶-1'-基）-1，3-氧硫杂环戊烷与β-D-半乳糖五乙酸酯反应合成了系列苷类似物的半乳糖衍生物。（7）将系列核苷类似物的乙酰化半乳糖糖苷及脱保护基的核苷类似物的半乳糖糖苷和拉米呋定纯品于2.2.15细胞株中进行抗病毒性能的药效研究，药效结果显示核苷类似物的乙酰化半乳糖糖苷均优于其完全脱保护基的半乳糖糖苷，也优于未与半乳糖偶联的母体核苷体化合物及抗乙肝病毒的药物拉米呋定。

PZT/PVDF压电复合材料的制备和性能研究

一.用压电陶瓷锆钛酸铅PZT粉末作为功能相，压电聚合物聚偏氟乙烯 PVDF作为活性（基体）相，静态热压法将PZT与PVDF粉复合，制得了不同陶瓷含量的0-3连通的复合材料薄膜样品。用FT-IR，SEM和WAXD表征复合材料：发现低PZT含量的复合材料中PVDF主要以α型结晶存在；复合材料呈现不同的网络形貌，主要为海岛型结构；70%PZT的复合材料较其它组成更均匀。复合材料的X射线衍射强度发生了变化，说明PZT与PVDF之间存在强烈的相互作用。一定电场和温度下对复合材料进行电晕极化研究，随着陶瓷含量的增加，压电性d_(33)也增加，同时材料的柔顺性降低。极化后的压电复合材料的X射线峰强度比未极化的增强，衍射角向低角度移动。二.研究PVDF相的转变。将PVDF薄膜加热到200 ℃，迅速冷到137 ℃结晶，同时施加直流电场作用于PVDF薄膜上，与未加电场的薄膜比较。用IR、X-ray衍射和DSC表征了上述PVDF薄膜，表明极化后PVDF膜的晶型由α型转为β型，β晶含量提高了23%，熔点提高。PVDF的压电性与β型晶有关，含量高，有利于压电性能的提高。电晕极化的PVDF薄膜，其压电性随着时间的流逝有所减弱，一定时间后达到稳定。研制了不同的极化设备，开发了PVDF测量血压用的传感器，探讨了微机控制电晕极化的可行性。

CHARACTERIZATION OF HIGH FLUENCE NEUTRON-INDUCED DEFECT LEVELS IN HIGH-RESISTIVITY SILICON DETECTORS USING A LASER DEEP-LEVEL TRANSIENT SPECTROSCOPY (L-DLTS)

Neutron irradiated high resistivity (4-6 kOMEGA-cm) silicon detectors in the neutron fluence (PHI(n)) range of 5 X 10(11) n/cm2 to 1 X 10(14) n/cm2 have been studied using a laser deep level transient spectroscopy (L-DLTS). It has been found that the A-center (oxygen-vacancy, E(c) = 0.17 eV) concentration increases with neutron fluence, reaching a maximum at PHI(n) almost-equal-to 5 X 10(12) n/cm2 before decreasing with PHI(n). A broad peak has been found between 200 K and 300 K, which is the result of the overlap of three single levels: the V-V- (E(c) = 0.38 eV), the E-center (P-V, E(c) = 0.44 eV), and a level at E(c) = 0.56 eV that is probably V-V0. At low neutron fluences (PHI(n) < 5 X 10(12) n/cm2), this broad peak is dominated by V-V- and the E-centers. However, as the fluence increases (PHI(n) greater-than-or-equal-to 5 X 10(12) n/cm2), the peak becomes dominated by the level of E(c) = 0.56 eV.

ENERGY-LEVEL CALCULATIONS OF THE RECONSTRUCTED 90-DEGREES PARTIAL DISLOCATION IN SILICON

An LCAO scheme taking into account 10 atomic orbitals (s-, p-, and d-type) applied to a supercell containing 256 atoms is used to calculate the bound states of the reconstructed 90-degrees partial dislocation in Si. The results differ significantly from our earlier calculations on the unreconstructed 90-degrees partial using the same method. We find two bands separate from each other in the entire Brillouin zone and the upper band penetrates deep into the indirect band gap which is in contradiction with the general opinion that core reconstruction clears the band gap of dislocation states.

PHOTOEMISSION-STUDY ON THE SNO2/P A-SICX-H INTERFACE

Ultraviolet and X-ray photoemission spectroscopies (UPS and XPS) have been employed to SnO2 and its interface with P-type a-SiCx:H. The HeI valence band spectra of SnO2 show that the valence band maximum (VBM) shifts from 4.7 eV to 3.6 eV below the Fermi level (E(F)), and the valence band tail (VBT) extends up to the E(F), as a consequence of H-plasma treatments. The work function difference between SnO2 and P a-SiCx:H is found to decrease from 0.98 eV to 0.15 eV, owing to the increase of the work function of the treated SnO2. The reduction of SnO2 to metallic Sn is also observed by XPS profiling, and it is found that this leads to a wider interfacial region between the treated SnO2 and the successive growth of P a-SiCx:H.

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.

A novel noise optimization technique for inductively degenerated CMOS LNA

This paper proposes a novel noise optimization technique. The technique gives analytical formulae for the noise performance of inductively degenerated CMOS low noise amplifier (LNA) circuits with an ideal gate inductor for a fixed bias voltage and nonideal gate inductor for a fixed power dissipation, respectively, by mathematical analysis and reasonable approximation methods. LNA circuits with required noise figure can be designed effectively and rapidly just by using hand calculations of the proposed formulae. We design a 1.8 GHz LNA in a TSMC 0.25 pan CMOS process. The measured results show a noise figure of 1.6 dB with a forward gain of 14.4 dB at a power consumption of 5 mW, demonstrating that the designed LNA circuits can achieve low noise figure levels at low power dissipation.

倒装结构大功率蓝光LEDs的研制

从器件制作角度入手，对基于Ⅲ族氮化物的功率型蓝光LEDs结构和电极体系进行了优化设计。采用梳状结构、高反电极体系及倒装焊技术，研制出大功率蓝光LEDs，在350mA工作电流下，工作电压为3．3～3．5V，输出功率达137．71mW，反向5V电压下的漏电流小于1μA。

射频CO_2激光陶瓷基板划片机光路设计及分析

介绍了RF c0