系统遗传学与生物技术-细胞分子生物系统的分析与合成

生物系统的科学与工程是整合系统论、实验、计算和工程方法的交叉学科研究与应用.系统生物学、系统医学,建立在系统科学和数学模型基础上,采用分子、组学生物技术和计算、生物信息技术,以及基因合成与转基因生物技术等研究生物系统原理和规律.系统遗传学与系统生物技术是研究天然与人工生物系统的基因系统与蛋白质系统构成细胞的软件信息与硬件运行系统的机理与方法.合成生物学、系统生物工程也是建立在系统科学和数学模型基础上,应用于生物系统原理设计虚拟计算机信息软件和仿生人工机器硬件、人造工程生物体和基因信息系统等.     

城市系统碳循环:特征、机理与理论框架

城市是地表受人类活动影响最深刻的区域,城市系统碳循环在全球和区域碳过程中具有重要的地位和作用.提出了城市“自然-社会”二元碳循环的概念,探讨了城市系统碳循环的一般特征;分析了城市系统碳循环的内部机理,主要包括:城市系统碳储量和碳输入/输出通量的主要过程和途径、城市系统碳储量、碳通量和碳流通的生命周期分析、城市系统碳输入和碳输出的类型划分等;提出了基于系统层次划分和碳流通过程的城市系统碳循环的研究框架,分析了城市自然系统和城市经济系统的主要碳流通过程和环节,构建了城市系统碳循环研究的思路和理论框架;最后提出了城市系统碳循环领域未来的研究重点.     

建德县南峰乡丘陵山地开发利用的生态经济规划研究Ⅱ．不同决策方案的系统模拟

采用系统动力学方法对6种不同的决策方案进行动态模拟和灵敏度分析,预测和分析各种决策方案的系统生产力、稳定性和持续性。结果表明,多目标规划型的系统生产力较高稳定性和持续性较好,是一种较优的选择方案;现状型的系统生产力较低,林主型的生产力很高,但经济产出水平低,柑桔、板栗和蚕桑型的系统生产力高,但系统的稳定性和持续性较差。     

生态创新系统功能、过程和可持续评估

不同国家生态创新水平有高低,生态创新系统有差异。生态创新系统是由一系列参与者通过相互作用形成的网络,目的是推动有助于生态环境和社会经济协调发展的知识和技术的生产、传播和应用。为比较不同国家生态创新系统的发展状况和可持续性,分析不同国家生态创新系统的优势和不足,提出生态创新系统两步评估法和整体分析框架。把生态创新系统的功能和过程结合起来,对生态创新系统的发展水平进行评价。重点关注系统的长期发展,即系统可持续性。基于资本的角度,包括知识、经济、人力和社会资本,建立生态创新系统可持续评估模型,考察相关资本存量、流量和风险因素。根据创新系统理论、文献回顾和国际研究比较,遴选出30个关键指标,构建涵盖2个指标矩阵的综合评价指标体系。采用主成分分析和综合评价方法,对不同国家生态创新系统的功能-过程和可持续性分别进行评价。研究表明,法国、德国、韩国、西班牙和挪威生态创新系统的功能-过程表现最强,韩国、德国、奥地利、挪威、捷克生态创新系统的可持续性表现最强。根据生态创新系统的现状和可持续性,主要生态创新国家可以分为四种类型,据此采用不同发展策略。如韩国系统现状水平和可持续性都较高,属于生态创新先进国。...     

枣粮间作系统节肢动物群落组成与时序动态

为揭示枣粮间作系统中枣园和农田两个亚系统节肢动物群落的关系,将枣粮间作系统区分为枣园亚系统和农田亚系统进行节肢动物生态调查并分析时序动态.调查共发现节肢动物14 936头,分属3纲、14目、96科,其中枣园亚系统个体5 992头,分属3纲、14目、82科,农田亚系统个体8 971头,分属3纲、14目、80科,且枣园、农田两个亚系统节肢动物群落的结构存在一定差异.对系统进行时间序列的最优分割可将其划分为4个不同的时期,即麦田亚系统衰落期、系统物种增长期、系统发展稳定期、系统动荡衰落期.系统主要天敌物种在4个阶段中表现出相互迁移的特性,且两个亚系统寄生性天敌物种对另一系统的害虫存在着制约作用.枣粮间作系统中枣园和农田两个亚系统节肢动物群落间的物种迁移和相互作用对提高系统的稳定性和控害能力有积极意义.     

“山地-绿洲-荒漠”复合系统土地利用变化的生态系统服务权衡与协同效应——以张掖市为例

开展复合生态系统土地利用变化的生态服务效应研究可为优化国土空间格局和强化生态系统管理提供重要的基础依据。以干旱区"山地-绿洲-荒漠"复合系统的典型区域张掖市为例,基于1987年、2000年和2018年3期土地利用数据,以乡级行政区为基本单元,引入相对优势度指数划分山地、绿洲、荒漠子系统,研究复合系统的土地利用变化特征及生态系统服务权衡/协同效应。结果表明：（1）张掖市复合系统呈现地域分异特征,由南部山地系统,中部绿洲系统和北部荒漠系统构成;山地系统以林地和草地为主,绿洲系统以耕地和建设用地为主,荒漠系统以未利用地为主。（2）从时间上看,2000-2018年各系统的土地利用变化更强烈,其中,绿洲系统的耕地面积增加量最大,为363.08km²,荒漠系统的建设用地面积增加幅度最大,为78.23%。各系统土地利用转移模式为：山地系统以草地转耕地为主,绿洲系统和荒漠系统以未利用地转耕地为主。（3）张掖市复合系统的生态服务价值呈增加趋势,其中,荒漠系统生态服务价值量的增幅最大,各子系统的价值量之间的关系表现为山地系统 > 绿洲系统 > 荒漠系统,耕地对各系统生态服务价值贡献量最大。（4）张掖市土地利用变化的协同效应大于权衡效应,其中荒漠系统的生态服务之间均为协同关系,山地系统中供给服务与其他服务呈现权衡关系,占比32.73%,绿洲系统中调节服务与其他服务呈现权衡关系,占比18.18%。     

林农复合生态系统的原理、特点及其类型

林农复合生态系统是根据生态位、生物种群之间共生、边缘效应、利用层、食物链“加环”和生态系统工程等原理建立起来的。林农复台生态系统依历史发展过程可分为原始林农复合系统、传统林农复会系统和现代林农复合系统;根据生产方式可分为“牧童”式、林农轮作式、林农间作式、食物网链式、树木菜园式、塘雅系统式和复合母系统式等７种类型;依复台种类及其用途来分,主要有林、农系统,林、牧系统,林、渔系统,林、渔、农系统。林、渔、牧系统,林、食用菌系统,林、水生作物、渔系统和林．副系统等８种类型。     

跨学科概念“系统及系统模型”的内涵与教学建议

系统及系统模型是科学教育高度关注的跨学科概念之一,它体现了人们认识复杂世界的方式。系统是根据研究目的人为界定的,它是有关联的物体或元件组成的有秩序整体,包含边界、组分及组分间的相互作用。其中组分与相互作用的总和作为系统的结构,与系统的功能之间互为因果。系统模型是描述和理解系统的有效工具,它根据研究目的对系统进行了必要的假设和近似,以突出系统的本质特征,但这些假设和近似会影响到系统模型的可信度和准确度。在基础教育理科课堂中以系统模型作为认知工具,并对系统及系统模型概念进行外显化的教学,将促使学生深入理解学科知识,提升课堂教学的质量。     

门脉系统

本文对门静脉和门静脉系统的概念作了扼要的阐述,并介绍了肝门静脉系统、肾门脉系统、垂体门脉系统、胰岛-腺泡门脉系统及肠绒毛门脉系统的结构和功能。     

农林复合系统固碳潜力研究进展

农林复合系统是解决当前资源枯竭、农林用地紧张和实现环境保护的一种可持续土壤管理模式。自《京都议定书》签订以来, 农林复合系统因其较高的固碳潜力引起了科学家的广泛关注。深入理解农林复合系统的固碳过程及其对气候变化、环境条件的改变和管理措施的响应, 是准确地预测农林复合系统在全球变化情景下固碳潜力的关键。该文综述了农林复合系统的概念和分类, 探讨了农林复合系统相比单一系统的固碳潜力及固碳机理, 分析了农林复合系统固碳潜力的测定方法和当前面临的挑战, 综述了气候因子、环境条件和人为管理措施对农林复合系统固碳潜力的影响。我国农林复合系统的固碳潜力相比全球其他区域还处于较低水平, 为提高我国农林复合系统的固碳潜力, 未来需要加强以下四个方面的工作: 扩大农林复合系统的分布面积、加强农林复合系统的合理配置和管理、选择适宜的物种组合和优化系统的群体结构。     

非自治阶段结构合作系统的持久性与周期解

本文研究一类非自治阶段结构的合作系统,得到系统的最终有界性,对应周期系统正周期解的存在性,唯一性以及全局渐近稳定性的充分条件。     

状态依赖脉冲微分方程的周期解的存在性及其在害虫治理中的应用

在文献[1]中研究的状态依赖脉冲微分方程的基础上,推广了其中的判定一般性平面自治状态依赖脉冲微分方程的准则,并利用它得到了文献[1]中所没有涉及到的情况下的状态依赖脉冲微分方程的阶一周期解☆栌在性．之后本文以此为基础并结合数值模拟的手段讨论了系统在农业害虫治理中的一些应用意义．     

Periodic solution of a chemostat model with Monod growth rate and impulsive state feedback control

In this paper, we develop a mathematical model concerning a chemostat with impulsive state feedback control to investigate the periodicity of bioprocess. By the existence criteria of periodic solution of a general planar impulsive autonomous system, the conditions under which the model has a periodic solution of order one are obtained. Furthermore, we estimate the position of the periodic solution of order one and discuss the existence of periodic solution of order two. The theoretical results and numerical simulations indicate that the chemostat system with impulsive state feedback control either tends to a stable state or has a periodic solution, which depends on the feedback state, the control parameter of the dilution rate and the initial concentrations of microorganisms and substrate.     

"Protistan" nomenclature: analysis and refutation of some potential objections

The nomenclature used for higher taxonomic categories of protista arose under the influence of the two-kingdom system, and is widely recognized as being evolutionarily misleading. The occurrence and promulgation of multiple, contradictory taxonomic systems have added to the confusion. Recently, we proposed a solution to this problem which involves identifying the largest taxa that are widely recognized to be monophyletic, and naming them using a commonly recognizable prefix and the suffix "protista". Thus, nomenclatural prejudice is eliminated, and, by keeping the system informal and thus circumventing the Linnaean system, our system remains flexible in accommodating new data yet should retain a great degree of stability. Here we discuss possible criticisms of our proposal, such as whether the introduction of more terms could lead to further taxonomic and nomenclatural instability, and conclude that our proposal remains a most reasonable solution to the problem of protistan nomenclature.     

Thermodynamic analysis of the interaction of the xylem water and phloem sugar solution and its significance for the cohesion theory

The cohesion theory explains water transport in trees by the evaporation of water in the leaves (transpiration), which in turn generates the tension required for sap ascent, i.e. the flow of pure water from the soil through the root system and the non-living cells of the tree (xylem tracheids) up to the leaves. Only a small part of this water flow entering the leaves is used in photosynthesis to produce sugar solution, which is transported from the leaves through the living cells (phloem) to everywhere in the tree where it is needed and used. The phloem sieves are connected to the xylem tracheids by water transparent membranes, which means that the upflow of pure water and downflow of sugar solution interact with each other, causing the osmotic pressure in the sugar solution (Münch model). In this paper we analyse this interaction with a thermodynamic approach and we show that some open questions in the cohesion theory can then perhaps be better understood. For example, why under a quite high tension the water can flow in the xylem mostly without any notable cavitation, and how the suction force itself depends on the cavitation. Minimizing Gibbs energy of the system of xylem and phloem, we derive extended vapor pressure and osmotic pressure equations, which include gas bubbles in the xylem conduits as well as the cellulose-air-water interface term. With the aid of the vapor pressure equation derived here, we estimate the suction force that the cavitation controlled by the phloem sugar solution can generate at high moisture contents. We also estimate the suction force that the transpiration can generate by moisture gradient at low moisture contents. From the general osmotic pressure equation we derive an equation for calculating the degree of cavitation with different sugar solution concentrations and we show the conditions under which the cavitation in the xylem is totally avoided. Using recent field measurement results for a Scotch pine, the theory is demonstrated by showing its predictions for possible amounts of cavitation or embolism from morning hours to late afternoon.     

Global exponential stability of positive periodic solution of the n-species impulsive Gilpin–Ayala competition model with discrete and distributed time delays

In this paper, we study the n-species impulsive Gilpin–Ayala competition model with discrete and distributed time delays. The existence of positive periodic solution is proved by employing the fixed point theorem on cones. By constructing appropriate Lyapunov functional, we also obtain the global exponential stability of the positive periodic solution of this system. As an application, an interesting example is provided to illustrate the validity of our main results.     

具有阶段结构的两种群竞争系统的周期解

本文研究了具有阶段结构的两种群竞争系统的渐近行为.我们得到了系统持续生存的条件.由Brouwer不动点定理和李亚普诺夫函数,我们证明相应的周期系统在满足一定的条件下,存在一个唯一的全局渐近稳定的正周期解.最后我们把没有阶段结构的系统与有阶段结构的系统进行了比较.     

关于一类非自治阶段结构捕食系统的持久性与周期解

本文研究了一类非自治阶段结构捕食系统的渐近性质,得到在适当的条件下系统的持久性,对应周期系统正周期解的存在性、唯一性以及全局渐近稳定性。     

液体培养蛹虫草虫草素和腺苷的代谢量

为提高虫草素和腺苷的代谢量,用高效液相色谱法作检测手段,以二者含量为检测指标,对液体培养的氮源种类、氮源水平、碳源水平、动态变化、培养体系的虫草素及腺苷含量和总量进行研究,结果表明:不仅蚕蛹粉,豆粕和豆粉也是很好的氮源;培养液以3%氮源、4%碳源为佳;振荡培养8d,培养液中虫草素总量是菌丝体中虫草素总量的6倍多;振荡培养7~9d,可使每瓶培养物的虫草素和腺苷总量达到10mg以上。     

Effect of hunting cooperation and fear in a predator-prey model

Dynamics of predator-prey systems under the influence of cooperative hunting among predators and the fear thus imposed on the prey population is of great importance from ecological point of view. The role of hunting cooperation and the fear effect in the predator-prey system is gaining considerable attention by the researchers recently. But the study on combined effect of hunting cooperation and fear in the predator-prey system is not yet studied. In the present paper, we investigate the impact of hunting cooperation among predators and predator induced fear in prey population by using the classical predator-prey model. We consider that predator populations cooperate during hunting. We also consider that hunting cooperation induces fear among prey, which has far richer and complex dynamics. We observe that without hunting cooperation, the unique coexistence equilibrium point is globally asymptotically stable. However, an increase in the hunting cooperation induced fear may destabilize the system and produce periodic solution via Hopf-bifurcation. The stability of the Hopf-bifurcating periodic solution is obtained by computing the Lyapunov coefficient. The limit cycles thus obtained may be supercritical or subcritical. We also observe that the system undergoes the Bogdanov-Takens bifurcation in two-parameter space. Further, we observe that the system exhibits backward bifurcation between predator-free equilibrium and coexisting equilibrium. The system also exhibits two different types of bi-stabilities due to subcritical Hopf-bifurcation (between interior equilibrium and stable limit cycle) and backward bifurcation (between predator-free and interior equilibrium points). Further, we observe strong demographic Allee phenomenon in the system. To visualize the dynamical behavior of the system, extensive numerical experiments are performed by using MATLAB and MATCONT softwares.