农药分子核酸适体筛选研究进展及其在生物传感器中的应用

核酸适体作为一类通过体外筛选指数富集配体系统进化技术(SELEX)得到的单链DNA或RNA,具有特异性强、稳定性好和靶分子广等特点,被广泛用于生化传感检测领域.总结了近年来筛选的农药分子核酸适体及其筛选方法,综述了农药分子核酸适体在生物传感检测中的应用,并探讨了农药分子核酸适体筛选的问题和未来发展的趋势.     

核酸适体的筛选及其在生物医学领域的研究进展

核酸适体是由指数富集配体系统进化技术(SELEX)筛选获得的能够与靶标物质特异性、高亲和力结合的单链DNA或RNA.能够被核酸适体识别的靶标物质包括各种小分子物质、大分子蛋白质、细胞等,广泛应用于生物医学研究各领域.为此,对核酸适体的筛选制备技术、对生物医学靶标物质的检测方法以及在疾病的靶向诊断和治疗中的研究进展进行了综述,并对其在生物医学领域中的应用进行了展望.     

RNA切割型脱氧核酶在生物医学领域中的研究进展

RNA切割型脱氧核酶（RCD）是一类具有催化活性的单链DNA分子,具有灵活的可编程性、优异的稳定性、强底物特异性和高催化活性等优点,因而在生物医学领域展现出了良好的应用前景. 基于RCD对于特定辅助因子的依赖和对于靶标RNA的特异性识别和切割,其被广泛应用于一系列生物分子靶标的检测以及多种临床疾病的基因治疗. 文章介绍了RCD的物理化学特性,并对其在生物医学领域的研究现状进行了总结,聚焦于RCD在生物传感和癌症治疗等方面的应用进展. 此外,还对该领域面临的挑战及未来的发展方向进行了讨论.     

单链DNA稳定的金纳米簇合成及其检测核酸外切酶Ⅰ活性研究

核酸外切酶Ⅰ在基因组活动和稳定性中起着重要作用,因此,快速检测核酸外切酶Ⅰ的活性对疾病诊断和药物开发具有深远的意义.设计一个高效的DNA模板合成荧光金纳米团簇(Au NCs),以其作为荧光探针,用于简单、灵敏和无标记的方式检测核酸外切酶Ⅰ(ExoⅠ)的活性.试验结果表明:随着核酸外切酶Ⅰ的加入,单链DNA将从3'端至5'端被消化,金纳米团簇失去了单链DNA模板的保护出现团聚,导致其荧光强度下降,可用于核酸外切酶Ⅰ活性测定.该方法不需要任何基团的修饰和特殊DNA序列的设计,提高了核酸外切酶I活性测定效率.     

MIL-101-NH2介导的核酸分子递送与基因沉默研究

核酸是DNA和RNA的总称,能够参与生物体内基因表达的调控.然而,核酸分子极易被降解,如果直接通过口服或静脉注射给药,生物利用率极低,因此需要合适的载体进行核酸的递送.选取了生物兼容性较好的铁基金属-有机框架（MOF）MIL-101-NH₂,分别负载单链DNA和siRNA来探究其细胞学行为.MIL-101-NH₂能够有效递送单链DNA和siRNA进入细胞,且siRNA在细胞内能够发生溶酶体逃逸,并发挥基因沉默的效应.结果表明：基于MIL-101-NH₂的纳米复合物是一种具有潜力的核酸递送与基因调控策略.     

基于λ核酸外切酶辅助的级联型铜离子荧光检测体系的构建

通过将一种有效的级联信号放大策略引入铜离子荧光生物传感器中,构建了一种用于超灵敏检测铜离子的荧光检测体系。这种级联型荧光检测体系结合了λ核酸外切酶辅助的靶标回收和催化发夹自组装的循环信号扩增。在铜离子的存在下,用于识别铜离子的功能核酸的底物链被特异性切割和释放。释放出的单链DNA片段(tDNA)与5′端被磷酸标记的双链DNA(TQ-DNA)杂交形成具有平末端的双链DNA。随后,该DNA分子被λ核酸外切酶识别并切割,释放出游离的tDNA和TDNA。随着λ核酸外切酶的水解,越来越多的tDNA被回收,同时放出越来越多的TDNA。此时,TDNA作为催化发夹自组装反应的触发链,启动了新一轮的靶标循环。在TDNA的辅助下,作为分子信标的发夹DNA会与另外一个发夹DNA杂交形成新的双链DNA,同时,释放出高荧光强度。利用荧光光谱法对该体系不同反应阶段进行了表征。结果表明,该级联型铜离子荧光检测体系对痕量铜离子具有很好的响应。     

核酸制品的开发应用

核酸是生物体细胞中由几十到几千万个单核苷酸聚合而成的高分子聚合物.1868年,英国科学家米歇尔(Miescher)首先从外科绷带的脓细胞的细胞核中发现.第二次世界大战之后,作为了解、阐明生命现象的途径,对脱氧核糖核酸(DNA),核糖核酸(RNA),核苷酸的生物合成途径,DNA、RNA合成与分解有关的酶系,代谢调节机制,生命信息的复制、传递等方面进行了广泛的研究,取得了惊人的成果.在核酸基础理论研究的同时,对核酸及核酸制品的应用研究也得到快速的发展.     

鸭瘟病毒基因组核酸的提取方法比较

将鸭瘟病毒分离株SD-01在鸡胚成纤维细胞上增殖.收集病变细胞及培养液,采用两种方法提取病毒基因组核酸.第一种方法,首先用差速离心的方法纯化病毒粒子,然后用酚/氯仿抽提的方法提取病毒基因组.第二种方法,先用高渗缓冲液将感染DPV的细胞完全裂解,然后加入微球菌核酸酶消化细胞DNA,最后用酚/氯仿抽提.限制性内切酶EcoR I消化,结果表明,第一种方法提取的样品中含有细胞DNA,酶切后为弥散模糊的拖带,而方法二可以最大限度的消除细胞DNA污染,得到纯净的病毒基因组DNA,酶切后为清晰的梯状条带.     

基于氧化石墨烯构建新型荧光生物传感器用于DNA检测

以氧化石墨烯作为荧光猝灭基底,羧基荧光素标记的DNA探针作为识别元件,设计了一种用于检测单链DNA的新型荧光生物传感器,通过测定荧光探针分子和目标DNA作用前后体系的荧光强度变化实现特定序列单链DNA的定量检测.在该方法中,荧光强度恢复值与目标DNA浓度在20～1 000 pM范围呈线性关系,检测限为0.11 pM.该...     

石墨烯/功能核酸电化学传感器在重金属离子检测中的研究进展

重金属离子由于其生物毒性大、易被富集、难于降解等特点，已严重威胁到人类的健康和安全。因此，开发快速、低成本、简单可靠的重金属离子检测方法具有非常重要的意义。近年来，基于石墨烯复合材料的电化学传感器具有高选择性、高灵敏度、低成本的特点，已广泛用于重金属离子的检测。而功能核酸作为新兴的识别元件，具有可媲美抗体的特异性识别作用，在电化学传感设计方面引起了广泛兴趣。本文对基于石墨烯复合材料/功能核酸的电化学传感器检测重金属离子的原理和研究进展进行综述，最后对其发展前景进行了展望。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-