空心束虚阴极激励微波的主模式的研究

把虚阴极振荡激励微波的过程看成是一个时空振荡电流元激励微波的过程,在薄电荷层近似下,求得空心束虚阴极激励微波的主模式关系,并讨论了束几何位形与微波输出功率之间的关系。我们所确定的主模式与实验和粒子模拟的结果相符。     

北京自由电子激光Wiggler中电子轨迹偏离的改进

提出了一种从实验上确定用于北京自由电子激光（ＢＦＥＬ）装置的Ｗｉｇｇｌｅｒ中ＮｄＦｅＢ矩形磁块的轨迹敏感系数β的方法．用β值来表征磁单块在Ｗｉｇｇｌｅｒ中对电子轨迹的贡献，并用此β值对磁块进行挑选，优化组合，可达到改进Ｗｉｇｇｌｅｒ对电子轨迹偏离的目的．     

地震CT勘探原理及其在公路隧道病害诊断中的应用

地震CT勘探是一种新的地球物理方法。具有分辨率高、可靠性强、信息量大、图象直观的特点。可以广泛地用于线路、场地、隧道、边坡等项目的工程地质勘查和病害诊断。在元磨高速公路芭蕉箐隧道的地质病害诊断中应用地震CT进行勘探,取得了良好的效果。     

Nucleophilic β‐Carbon Activation of Propionic Acid as a 3‐Carbon Synthon by Carbene Organocatalysis

Direct β‐carbon activation of propionic acid (C₂H₅CO₂H) by carbene organocatalysis has been developed. This activation affords the smallest azolium homoenolate intermediate (without any substituent) as a 3‐carbon nucleophile for enantioselective reactions. Propionic acid is an excellent raw material because it is cheap, stable, and safe. This approach provides a much better solution to azolium homoenolate synthesis than the previously established use of acrolein (enal without any substituent), which is expensive, unstable, and toxic.     

Enantioselective Diels-Alder reactions of enals and alkylidene diketones catalyzed by N-heterocyclic carbenes

An electron-withdrawing group was introduced to the α-position of chalcones, and the resulting alkylidene diketones showed new reactivities with enals under the catalysis of N-heterocyclic carbenes (NHCs). Selective activation of enals affords enolate equivalents that undergo highly enantioselective intermolecular Diels-Alder reactions with the alkylidene diketones. No products that might have resulted from typical homoenolate pathways were observed.     

Ocular Pharmacokinetic Study of l-Carnosine and N-Acetyl-l-carnosine in Rabbit by Microdialysis Coupled with UPLC-MS-MS

In order to provide useful information for rational drug design, the ocular pharmacokinetics of l-carnosine (CAR) and its acetylized prodrug N-acetyl-l-carnosine (NAC) were investigated. The in vivo microdialysis sampling coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) was developed for continuously simultaneous monitoring of CAR and NAC in rabbit aqueous humor. The measured in vitro recoveries of the probe were 61.3% for CAR and 65.8% for NAC, while in vivo recoveries decreased to 43.1% for CAR and 43.0% for NAC, respectively. The method was sensitive with LLOQ 20.5 ng mL^?1 for CAR and 20.4 ng mL^?1 for NAC. The initial data indicated that the value of C _max and AUC_(0?C??) of NAC were higher than these of CAR (C _max 2305 vs. 1,802 ng mL^?1), (AUC_(0?C??) 1,337 vs. 1,891 ng h mL^?1), which indicated that the NAC exhibited better ocular bioavailability and duration. The method was rapid, specific and sensitive for continuously monitoring of aqueous humor and it was successfully applied to pharmacokinetic studies of CAR and NAC.     

计算Adomian多项式的新算法

本文给出了一个计算Adomian多项式的新算法,并将其用于求微分方程的近似 解.我们的算法比原有算法效率高,且易于在计算机上实现.我们在Maple中实现了这一 算法,并通过30多个微分方程的求解验证了新算法的有效性.     

Tunable optical-path correlator for distributed strain or temperature-sensing application

Based on a cavity-length tunable fiber-loop resonator, a multibeam optical path difference is generated. It can be used to match and correlate the reflective signals from the partial reflective ends of each sensing fiber gauge. The correlation signals correspond to the sensing gauge lengths, and the shift of the correlation peak is related with the fiber sensing gauge elongation caused by strain or temperature. Therefore, it can be used to measure distributed strain or deformation for smart structural monitoring.