基于PCI总线的数字下变频模块设计

提出了一种基于ＰＣＩ总线的数字下变频模块设计方案,它与商业化的ＤＳＰ处理板相结合,可以构成一个完整的多制式数字接收机。文中首先介绍它的总体结构,并分析了其中主要功能模块的工作原理,最后着重阐述全局控制器的设计与主控程序的工作流程。     

无线通信中的空时编码

空时编码是最近提出的使用多个天线应用于瑞利衰落信道的编码技术。结合分集技术对空时编码进行了综述,包括系统模型、编译码方法、设计准则,在此基础上介绍了空时编码与外码的级联。     

地方博物馆的材料运用初探

随着博物馆的飞速发展,博物馆建筑越来越受到国内各方面的重视。作为一个重要的文化载体．出于保护文化、宣传文化的目的．地方博物馆也雨后春笋般出现在全国各地。如何设计一个富有地方特色,带有地方传统文化的博物馆成为建筑师们首要解决的问题。材料,作为建筑造型的物质基础,应当首先被考虑进去。而随着材料的不断发展,各种新型材料涌现,既冲击着地方传统特色,又为地方文化的传承带来了新的途径．．本文通过地域主义．材料学的交叉研究来探寻地方博物馆乃至地域性建筑设计的新思路、新途径。     

Surface Coating‐Dependent Cytotoxicity and Degradation of Graphene Derivatives: Towards the Design of Non‐Toxic,Degradable Nano‐Graphene

With the increasing interests of using graphene and its derivatives in the area of biomedicine, the systematic evaluation of their potential risks and impacts to biological systems is becoming critically important. In this work, we carefully study how surface coatings affect the cytotoxicity and extracellular biodegradation behaviors of graphene oxide (GO) and its derivatives. Although naked GO could induce significant toxicity to macrophages, coating those two‐dimensional nanomaterials with biocompatible macromolecules such as polyethylene glycol (PEG) or bovine serum albumin (BSA) could greatly attenuate their toxicity, as independently evidenced by several different assay approaches. On the other hand, although GO can be gradually degraded through enzyme induced oxidization by horseradish peroxidase (HRP), both PEG and BSA coated GO or reduced GO (RGO) are rather resistant to HRP‐induced biodegradation. In order to obtain biocompatible functionalized GO that can still undergo enzymatic degradation, we conjugate PEG to GO via a cleavable disulfide bond, obtaining GO‐SS‐PEG with negligible toxicity and considerable degradability, promising for further biomedical applications.     

Light‐Responsive,Singlet‐Oxygen‐Triggered On‐Demand Drug Release from Photosensitizer‐Doped Mesoporous Silica Nanorods for Cancer Combination Therapy

Smart drug delivery systems with on‐demand drug release capability are rather attractive to realize highly specific cancer treatment. Herein, a novel light‐responsive drug delivery platform based on photosensitizer chlorin e6 (Ce6) doped mesoporous silica nanorods (CMSNRs) is developed for on‐demand light‐triggered drug release. In this design, CMSNRs are coated with bovine serum albumin (BSA) via a singlet oxygen (SO)‐sensitive bis‐(alkylthio)alkene (BATA) linker, and then modified with polyethylene glycol (PEG). The obtained CMSNR‐BATA‐BSA‐PEG, namely CMSNR‐B‐PEG, could act as a drug delivery carrier to load with either small drug molecules such as doxorubicin (DOX), or larger macromolecules such as cis‐Pt (IV) pre‐drug conjugated third generation dendrimer (G3‐Pt), both of which are sealed inside the mesoporous structure of nanorods by BSA coating. Upon 660 nm light irradiation with a rather low power density, CMSNRs with intrinsic Ce6 doping would generate SO to cleave BATA linker, inducing detachment of BSA‐PEG from the nanorod surface and thus triggering release of loaded DOX or G3‐Pt. As evidenced by both in vitro and in vivo experiments, such CMSNR‐B‐PEG with either DOX or G3‐Pt loading offers remarkable synergistic therapeutic effects in cancer treatment, owing to the on‐demand release of therapeutics specifically in the tumor under light irradiation.     

室内空气中挥发性有机污染物防治方法的研究

室内环境质量的优劣直接影响到人们的工作和生活,也直接影响到人体的健康。随着人们在室内生活的时间越来越长,对室内环境质量的要求越来越高。因此,室内环境污染的防治显得尤为重要。文章主要讨论目前中国室内空气污染的现状、主要污染物的来源及危害,列出了相应的防治方法,并提出我国在室内VOCS污染研究中现存问题和发展方向。     

电子分析天平称量数据预处理方法研究

如何提高稳定度和灵敏度一直是电子分析天平的研究重点。本文介绍了电子分析天平的称重原理,构建了一种称量数据自适应滤波方法,以提高天平称量的稳定性和准确度;依据电磁力平衡传感器的动态响应特性,利用设定的多个阈值对连续称量数据单元进行多级判别,建立了一种称量数据多阈值判别方法,提高了天平的响应速度。计量测试结果表明,基于上述称量数据预处理方法研制的量程210g、分辨率0.1 mg的电子分析天平响应时间0.3s,稳定时间≤4s,称量的最大允许误差MPE≤±0.3mg,优于国家标准《JJG1036-2008电子天平检定规程》规定的一级天平示值误差指标。     

Experimental study on the oil pump driving energy consumption and lubrication safety in a PFI engine under NEDC and WLTC

Journal of Mechanical Science and Technology - We studied the transient driving power of an oil pump for 1.6 L PFI engine in a passenger car under the new European driving cycle (NEDC) and...     

采用遗传算法的文本无关说话人识别

为解决在说话人识别方法的矢量量化(Vector Quantization,VQ)系统中,K-均值法的码本设计很容易陷入局部最优,而且初始码本的选取对最佳码本设计影响很大的问题,将遗传算法(Genetic Algorithm,GA)与基于非参数模型的VQ相结合,得到1种VQ码本设计的GA-K算法.该算法利用GA的全局优化能力得到最优的VQ码本,避免LBG算法极易收敛于局部最优点的问题;通过GA自身参数,结合K-均值法收敛速度快的优点,搜索出训练矢量空间中全局最优的码本.实验结果表明,GA-K算法优于LBG算法,可以很好地协调收敛性和识别率之间的关系.     

氟环唑在苹果及土壤中的残留动态研究

为了解氟环唑在苹果上使用的安全性,分别在天津和安徽两地进行了氟环唑在苹果和土壤中的残留消解规律和最终残留研究,试样经溶剂浸泡提取,层析柱净化,用气相色谱定量。结果表明,氟环唑的最低检出量为1.93×10-13g,在苹果和土壤中的最低检出浓度分别为9.65×10-5mg·kg-1和1.21×10-4mg·kg-1;苹果中氟环唑的平均回收率为88.94%～91.86%,变异系数为5.88%～6.63%;土壤中氟环唑的平均回收率为98.89%～103.03%,变异系数为2.96%～6.33%。氟环唑消解较快,在苹果中其半衰期两地分别为8.21d和11.46d,土壤中其半衰期两地分别为11.53d和16.43d。按推荐剂量(900倍稀释液)2倍施用3次,距最后一次施药间隔21d后,苹果中氟环唑的残留量为0.267～0.033mg·kg-1,土壤中的氟环唑残留量为0.143mg·kg-1～0.123mg·kg-1。说明该药属易分解农药(T1/2<30d),按推荐剂量使用是安全的。