地表基质调查是新时代自然资源调查监测与地质工作的新领域,分类是地表基质调查的前提。为尽快掌握全国或省级更大区域的地表基质空间格局,需借鉴相关学科概念、充分利用已有基础调查成果,探索分类方案。质地是地表基质内不同颗粒的组...地表基质调查是新时代自然资源调查监测与地质工作的新领域,分类是地表基质调查的前提。为尽快掌握全国或省级更大区域的地表基质空间格局,需借鉴相关学科概念、充分利用已有基础调查成果,探索分类方案。质地是地表基质内不同颗粒的组合状况,基于质地类型刻画地表基质类型,有助于明确其孕育林草生态要素的本底特征。新疆地域广阔、地貌复杂,地貌是该区自然资源与地表基质质地分类空间分异的主控因素。本研究利用数字高程模型、遥感影像、土地利用、土壤性质、植物特征等多源信息,确定新疆地貌三级区划方案,基于地貌区划提出地表基质质地的分类方案。将新疆按坡度、起伏度、高程和成因分为47种地貌类型,划分6个一级、27个二级和1056个三级地貌区。山地区的三级地貌区数量高于平原区,中海拔丘陵是分布最广泛的三级地貌类型,中起伏中山和中海拔风积地貌分别是山地和平原内面积最大的三级地貌类型。大部分地貌类型的植被根系深度平均值低于100 cm, 0~200 cm的土壤信息足以描述新疆地表基质结构。不同三级地貌类型的0~200 cm内主要土壤质地类型的数量占比均值为70.9%,表明在新疆采用基于地貌的地表基质质地分类具有一定可靠性。粉壤质、砂质和砾质是新疆的主要地表基质质地,分别占全疆面积的49.6%、27.1%和10.3%。粉壤质是新疆森林、草原与耕地资源数量与质量最高的质地分类。基于地貌类型的地表基质质地分类方案兼顾了水热条件与地表物质组成,有助于评价不同类别自然资源的适宜性,可为新疆土地整治与生态修复提供重要参考。展开更多
Soilless culture refers to the technique by which crops are grown using nutrient solution or solid substrate along with nutrient solution without natural soil. This technique has developed for more than 150 years, and...Soilless culture refers to the technique by which crops are grown using nutrient solution or solid substrate along with nutrient solution without natural soil. This technique has developed for more than 150 years, and plays an essential role in promoting the development of horticultural, agricultural and forestal production, as well as agricultural modernization. Substrate and nutrient solution formulae and their application are the core of soilless culture technique. Based on the classification system of soilless culture, the types, advantages and scope of application of substrate formulae for growing vegetables and flowers in soilless culture, as well as the types, advantages and scope of application of nutrient solution formulae, and the regulation of nutrient solution ingredients are first systematically summarized in this paper; then, the advantages and disadvantages of the inorganic energy-intensive soilless culture and eco-organic soilless culture, and their scopes of application are analyzed; finally, research directions for further perfecting soilless culture technique are presented, and the outlook for the application of soilless culture is also provided.展开更多
An inspection of the φ-ψ angle distribution strongly suggests that protein folding is highly constrained. A number of researchers have even suggested that a relatively small set of discrete φ-ψ regions might be su...An inspection of the φ-ψ angle distribution strongly suggests that protein folding is highly constrained. A number of researchers have even suggested that a relatively small set of discrete φ-ψ regions might be sufficient to describe most protein conformation. The total of 541 tight turns from 101 non-identical proteins were extracted form Brookhaven DataBank. The dihedral values of tight turns were scattered into the seven regions on the Ramachandran plot. These seven regions were called A1, A2, B1, B2, B22, T1 and T2. A1 and A2 are the traditional a-helix regions, B1, B2 and B22 the β-strand regions, Tl and T2 the β-turn regions. The A2 and T2 regions were not defined as 'discrete' or single points but rather as one dimensional extended states. Based on the geometry of the two central residues of the tight turns, the new classification of β-turn was defined. This classification of the majority of β-turns fell into only six of the possible forty nine region combinations and were identifiable with the traditional nomenclature of Venkat-achalam(1), but much simpler.The function of β-turn in the conformation of proteins was studied. The hydrophobicity for different type turns was discussed. It shows that β-turns have very strong hydrophilic property, so they are usually situated at the folding protein surface. The features of β-turn and its amino acid distribution in this 541 β-turn group and different type β-turn were given.展开更多
The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of th...The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categorized into 7 types as rocks, boulders, cobbles, pebbles, gravels, sand and silt. There were 23 sampling sites each with 2 stretches of around 100m in those rivers. The data were taken as a percentage, and to avoid biases it was observed visually by the same person for a complete year in every season. With 23 sites each with 2 stretches and 4 replicates corresponding to 4 seasons, there are altogether 184 observations, each termed as a case, that constitute this work. Canonical Discrimination Analysis (CDA) which is most suitable when the data pool is huge was applied to see if the rivers studied distinguish themselves in terms of its morphology. The result was remarkably successful and was close to the established regional classification of the rivers. This kind of river classification has great application in the utilization, conservation and restoration of the most important natural re-source of the country.展开更多
文摘地表基质调查是新时代自然资源调查监测与地质工作的新领域,分类是地表基质调查的前提。为尽快掌握全国或省级更大区域的地表基质空间格局,需借鉴相关学科概念、充分利用已有基础调查成果,探索分类方案。质地是地表基质内不同颗粒的组合状况,基于质地类型刻画地表基质类型,有助于明确其孕育林草生态要素的本底特征。新疆地域广阔、地貌复杂,地貌是该区自然资源与地表基质质地分类空间分异的主控因素。本研究利用数字高程模型、遥感影像、土地利用、土壤性质、植物特征等多源信息,确定新疆地貌三级区划方案,基于地貌区划提出地表基质质地的分类方案。将新疆按坡度、起伏度、高程和成因分为47种地貌类型,划分6个一级、27个二级和1056个三级地貌区。山地区的三级地貌区数量高于平原区,中海拔丘陵是分布最广泛的三级地貌类型,中起伏中山和中海拔风积地貌分别是山地和平原内面积最大的三级地貌类型。大部分地貌类型的植被根系深度平均值低于100 cm, 0~200 cm的土壤信息足以描述新疆地表基质结构。不同三级地貌类型的0~200 cm内主要土壤质地类型的数量占比均值为70.9%,表明在新疆采用基于地貌的地表基质质地分类具有一定可靠性。粉壤质、砂质和砾质是新疆的主要地表基质质地,分别占全疆面积的49.6%、27.1%和10.3%。粉壤质是新疆森林、草原与耕地资源数量与质量最高的质地分类。基于地貌类型的地表基质质地分类方案兼顾了水热条件与地表物质组成,有助于评价不同类别自然资源的适宜性,可为新疆土地整治与生态修复提供重要参考。
文摘Soilless culture refers to the technique by which crops are grown using nutrient solution or solid substrate along with nutrient solution without natural soil. This technique has developed for more than 150 years, and plays an essential role in promoting the development of horticultural, agricultural and forestal production, as well as agricultural modernization. Substrate and nutrient solution formulae and their application are the core of soilless culture technique. Based on the classification system of soilless culture, the types, advantages and scope of application of substrate formulae for growing vegetables and flowers in soilless culture, as well as the types, advantages and scope of application of nutrient solution formulae, and the regulation of nutrient solution ingredients are first systematically summarized in this paper; then, the advantages and disadvantages of the inorganic energy-intensive soilless culture and eco-organic soilless culture, and their scopes of application are analyzed; finally, research directions for further perfecting soilless culture technique are presented, and the outlook for the application of soilless culture is also provided.
基金This work was supported by the National Natural Sciences Foundation.
文摘An inspection of the φ-ψ angle distribution strongly suggests that protein folding is highly constrained. A number of researchers have even suggested that a relatively small set of discrete φ-ψ regions might be sufficient to describe most protein conformation. The total of 541 tight turns from 101 non-identical proteins were extracted form Brookhaven DataBank. The dihedral values of tight turns were scattered into the seven regions on the Ramachandran plot. These seven regions were called A1, A2, B1, B2, B22, T1 and T2. A1 and A2 are the traditional a-helix regions, B1, B2 and B22 the β-strand regions, Tl and T2 the β-turn regions. The A2 and T2 regions were not defined as 'discrete' or single points but rather as one dimensional extended states. Based on the geometry of the two central residues of the tight turns, the new classification of β-turn was defined. This classification of the majority of β-turns fell into only six of the possible forty nine region combinations and were identifiable with the traditional nomenclature of Venkat-achalam(1), but much simpler.The function of β-turn in the conformation of proteins was studied. The hydrophobicity for different type turns was discussed. It shows that β-turns have very strong hydrophilic property, so they are usually situated at the folding protein surface. The features of β-turn and its amino acid distribution in this 541 β-turn group and different type β-turn were given.
文摘The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categorized into 7 types as rocks, boulders, cobbles, pebbles, gravels, sand and silt. There were 23 sampling sites each with 2 stretches of around 100m in those rivers. The data were taken as a percentage, and to avoid biases it was observed visually by the same person for a complete year in every season. With 23 sites each with 2 stretches and 4 replicates corresponding to 4 seasons, there are altogether 184 observations, each termed as a case, that constitute this work. Canonical Discrimination Analysis (CDA) which is most suitable when the data pool is huge was applied to see if the rivers studied distinguish themselves in terms of its morphology. The result was remarkably successful and was close to the established regional classification of the rivers. This kind of river classification has great application in the utilization, conservation and restoration of the most important natural re-source of the country.
