Making chiral molecular knots and links stereospecifically

<正>Topological structures [1,2],i.e.,knots and links,grace the macroscopic world in the form of biomorphs and artificial tools,all the way down to the molecular scale,such as catenated DNA and phytochromes.Chirality inherently exists in structures in which mirror-image topologies cannot be superimposed upon themselves without disassembling the topological structures.Although the chirality we are most familiar with is based on stereogenic centers,     

Optimal control and pattern formation for a haptotaxis model of solid tumor invasion

This paper deal with an optimal control problem for a haptotaxis model of solid tumor invasion by considering the multiple treatments of cancer (a combination of radiotherapy and chemotherapy). Firstly, we obtain the existence and uniqueness of weak solution for the controlled system with spatial dimensions $N=1,2,3$ by applying the Leray–Schauder fixed point theorem and developing adapted a priori estimates. Subsequently, the existence of optimal pair are proved by means of the technique of minimizing sequence. Furthermore, we verify the Lipschitz continuity of control-to-state mapping based on some a priori estimates, hence derive the first-order necessary optimality condition and establish the optimality systems. Finally, the ringlike diffusion and aggregation patterns and the dynamics of tumor invasion as well as the optimal control strategies are presented numerically, which demonstrate that the optimal treatment strategies are capable of breaking the pattern formation, and preventing the tumor invading and metastasizing, even eliminating the tumor possibly. The results of this work improved and extended previous results partially.     

基于价值网络的企业产出优势:特点与构成

针对基于企业信息网络进行价值创造的活动特征,提出了一个企业内部产出的概念,并运用企业价值网络理论分析了企业非官方活动所带来的企业内部产出的特点和构成,阐述了企业内部产出和外部产出之间的关系,指出,企业非官方活动能为企业外部产出带来显著的成本优势和差异化优势;认为,要有效实现企业内部产出对其最终产出价值优势的贡献.企业至少应努力建立:宽松的文化和制度环境、与企业战略相容的相关利益主体的效用体系、非官方活动与官方活动协调与转化机制,以促进企业非官方活动的健康发展。     

关于民营中小企业融资渠道的探讨

民营中小企业融资渠道狭窄是当前制约我国民营中小企业发展的突出问题，针对于民营中小企业融资渠道的问题进行探讨，目的在于拓宽民营中小企业的融资渠道。同时以经济学、财政学及金融学为理论依据，提出了几种目前切实可行的民营中小企业融资的渠道。     

Hunting field: insights on distribution pattern of bacteria and immune cells in solid tumors

Bacterial cancer therapy, which was first applied in the clinic in 1868, has regained attention owing to the recent progress made in synthetic biology.Consideri...     

Search on surfaces: Exploring the potential of interactive tabletops for collaborative search tasks

Collaborative information seeking often takes place in co-located settings; such opportunities may be planned (business colleagues meeting in a conference room or students working together in a library) or spontaneous (family members gathered in their living room or friends meeting at a café). Surface computing technologies (i.e., interactive tabletops) hold great potential for enhancing collaborative information seeking activities. Such devices provide engaging direct manipulation interactions, facilitate awareness of collaborators’ activities, and afford spatial organization of content. However, current tabletop technologies also present several challenges that creators of collaborative information seeking system must account for in their designs. In this article, we explore the design space for collaborative search systems on interactive tabletops, discussing the benefits and challenges of creating search applications for these devices. We discuss how features of our tabletop search prototypes TeamSearch, FourBySix Search, Cambiera, and WeSearch, illustrate different aspects of this design space.     

西藏保护地黄瓜主要病害的发生规律与综合防治

黄瓜霜霉病、细菌性角斑病、蔓枯病，是保护地黄瓜生产上发生普遍而又严重的病害，我区黄瓜种植区均有发生，尤其以拉萨、林芝、山南、日喀则等地城郊菜田保护地发生严重，常造成产量损失20%-30%左右。本文结合试验研究结果、黄瓜主要病害的症状特点、传播途径与发生规律，提出了保护地黄瓜主要病害的综合防治技术与措施，对指导我区蔬菜病虫害的综合防治、发展优势、高产、高效的无公害蔬菜生产具有重要的实际应用价值。     

广西含镉危险固体废物处置现状及研究进展

广西是有色金属之乡,重金属污染是地方环境保护工作的重要内容。含镉固体废物是有色金属行业主要的固体污染源,大部分属于危险废物范畴,对生态环境具有较大的潜在威胁。文章通过对广西含镉危险固体废物的来源及处置现状的概述,总结当前含镉危险固体废物处置所面临的主要问题,并通过当前含镉固体废物处置技术的对比,提出了含镉固体废物处置技术发展方向的建议。     

Recent insights on biochemical and molecular basis for developing antihaemostatic agents: A review

The normal coagulation process is initiated by disruption and exposure of the subendothelial components of blood vessels. Platelets adhere to subendothelium-bound von Willebrand factor via glycoprotein (GP) Ib complex. This initial interaction per se and the release of platelet agonists transduce signals that leads to the rise in intracellular Ca2+ which induces shape change, prostaglandin synthesis, release of granular contents and conformational changes in platelet Gp IIb-IIIa. Gp IIb-IIIa in activated platelets binds fibrinogen and other adhesive proteins and mediates platelet cohesion the primary haemostatic plug. Furthermore, the activated platelets due to aggregation, result in the formation of fibrin (secondary hemostasis). Normally the haemostatic process plays a delicate balance between keeping the blood in the fluid state to maintain flow and rapidly forming an occluding plug following vessel injury. Thrombosis occurs because of alteration in this delicate balance. Arterial thrombosis occurs in the setting of previous vessel wall injury mostly because of atherosclerosis, while venous thrombosis occurs in areas of stasis. The recent advances in understanding of the haemostatic process have led to a better understanding of the mechanism of action of many antithrombotic drugs and identification of new targets for drug development. The molecular target of the ticlopidine has been identified. Large numbers of IIb-IIIa inhibitors have been developed. The mechanism of action of heparin has been defined at the molecular level. As a result, a synthetic pentasaccharide, based on antithrombin-binding domain of heparin, has been developed and tested successfully in clinical trials. New generation direct thrombin inhibitors are being developed. Factor Xa has a critical position at the convergence of intrinsic and extrinsic pathway. The clinical tolerability and the efficacy of low molecular weight heparins has established that inhibition of further thrombin generation, by blocking factor Xa alone can be an effective way of preventing thrombus growth without inactivating thrombin. A large number of specific factor Xa inhibitors are under development. Some of these are in preliminary clinical trials and appear to be promising. Future clinical trials will determine whether these new drugs will provide better risk-benefit ratio in treatment of thrombotic disorders. Similarly role of thrombolytics has been clearly established in many diseases including coronary artery disease.     

知识来源与形成的探讨

本文对知识来源与形成进行了初步的研究.指出人类知识来源于人类实践活动、人类长期积累的知识以及某些生理性的认知天赋;介绍了知识的现代信息加工模型;阐明了此项研究成果对情报学理论研究的影响.     

知识来源与形成的探讨(续)

5　知识来源的现代信息加工模型知识的现代信息加工模型是一种阐明知识来源、形成和机制的理论模型 ,它比较深入地揭示了认知主体与客体相互作用的关系。所谓知识 ,就是认知主体与外界输入的信息相互作用的产物。外界输入的信息包括两大部分 :一部分是客体刺激认知主体的感官 ,在认知主体心智操作中枢的大脑生成映象、感知。另一部分是人类现有的知识—经验 ,按照认知主体的需要被汲入大脑。这两部分信息与脑中存贮的知识相融合 ,通过适应、同化、重构、观念化构成新的知识。如果能用语言、文字符号表达 ,就形成了意会知识。无论编码知识 ,…     

Y6 and its derivatives: molecular design and physical mechanism

Non-fullerene-acceptor(NFA)materials in the bulk heterojunction(BHJ)play an important role in high-performance organic solar cells(OSCs).Recently,Y-series accep...     

Strain in perovskite solar cells: origins,impacts and regulation

Metal halide perovskite solar cells (PSCs) have seen an extremely rapid rise in power conversion efficiencies in the past few years. However, the commercialization of this class of emerging materials still faces serious challenges, one of which is the instability against external stimuli such as moisture, heat and irradiation. Much focus has deservedly been placed on understanding the different origins of intrinsic instability and thereby enhancing their stability. Among these, tensile strain in perovskite films is an important source of instability that cannot be overcome using conventionally extrinsic stabilization approaches such as encapsulation. Here we review recent progress in the understanding of the origin of strain in perovskites as well as its corresponding characterization methods, and their impacts on the physical properties of perovskites and the performance of PSCs including efficiency and stability. We then summarize the latest advances in strain-regulation strategies that improve the intrinsic stability of perovskites and photovoltaic devices. Finally, we provide a perspective on how to make further progress in stable and high-efficiency PSCs via strain engineering.     

环境约束对外商直接投资企业研发创新的影响-基于PSM方法的研究

在中国产业结构优化升级的过程中,外商直接投资对产业研发创新的重要性日益凸显,与此同时,为应对日益严峻的环境污染问题所制定的环境保护政策是否会对外资企业研发创新造成影响。文本利用2004~2007年企业层面微观数据,采用倾向得分匹配方法全面系统地评估了环境约束对外资企业研发创新的影响。结果表明：环境规制与外资企业研发创新存在显著的相关关系,其对外资企业研发创新的影响不仅具有即时性,同时具有持续性;此外,研究还发现环境规制对不同行业类型外资企业研发创新的影响也存在差异。