基施氮肥对冬小麦产量、氮肥利用率及氮平衡的影响

通过田间小区试验研究了氮肥一次基施对高肥力土壤上冬小麦产量,吸氮量及氮肥利用率的影响,旨在了解高肥力土训上减少基肥氮的可行性,结果表明,高肥力土壤上冬小麦产量对氮肥的反应不明显,而施用氮肥显著增加了冬小麦吸氮量,根据差值法计算结果,当施氮量为75,112．5和150kg/hm^2时冬小麦的氮肥利用率分别为16．0％,14．5％和13．5％,表明多达84％－86．5％以上的基肥氮未被作物吸收利用,氮平衡计算的结果进一步表明,未被当季小麦利用的肥料氮主要以无机氮的形式残留于0－1m土体中,当施氮量分别为75,112．5和150kg/hm2时氮肥的土壤残留率依次为83．3％,46．0％和58．8％,而相应的表观损失率为0．5％,38．9％和19．0％,由此可见,在高肥力土壤上应严格控制基肥氮的用量或不施基肥,否则将造成氮素资源的大量浪费。     

The Effects of Workstation Flexibility on the (N × N) Job Shop Problem

To obtain insight into the potential for improving FMS design and operation, workstation flexibility is examined using shop problems of various sizes. Simulation results show a near-linear relationship, with average performance improvement explaining 92% of the variation. The results are based on 58,320 simulations, 30 replications of each of the 1,944 combinations of sharing m worksations from 6 × 6 through 10 × 10 job shops. The strong probabilistic relations suggest that analytical methods of prediction may exist. The results provide practitioners with several guidelines for process plan development and FMS design and operation.     

N. V. Timofeev-Resovski? and the development of molecular radiobiology of eukaryote gene]

The nature and mechanisms of formation of spectrum and frequency of gene mutations induced by ionizing radiation of different quality have been the two key interdependent problems in radiation mutagenesis (at the gene level) of higher eukaryotes. The history of both problems, that were first given consideration by N.W.Timofeeff-Ressovsky, a known Russian radiobiologist and evolutionist, has been followed up. The author emphasizes some characteristic features of methodology of those works and shows that negative consequences for the development of the theory of radiation mutagenesis of higher eucaryotes are unavoidable if the study on the problems is carried out with the use of different approaches and test-systems. The joining up of both methods used by N.W.Timofeeff-Ressovsky in various time periods and for different purposes (analysis of the spectrum and frequency of mutations of individual genes, on the one hand, and modification analysis of the processes that lead to these mutations, on the other) and the use of current molecular and genetic methods signifies a qualitatively new stage in studying the above-mentioned problems and the onset of a new scientific orientation, that is, molecular radiobiology of an eukaryote gene.     

The role of N. I. Vavilov in the development of Soviet genetics and animal selection

N. I. Vavilov had been greatly interested in the problems of animal industry, genetics, breeding, origin and evolution of domestic animals. Due to his initiative and active participation in discussing these problems, important programmes were developed. The unique ideas of Nikolai Ivanovich had significant impact on a rise of animal genetics in the USSR.     

森林土壤氮素可利用性的影响因素研究综述

近几十年来 ,人类对木材、纤维和其他森林资源需求的急剧增加 ,对森林的集约化经营管理成为必然趋势。由于大部分森林生态系统缺乏Ｎ素 ,因此施肥成为经济有效的途径。但是 ,由于森林中的Ｎ肥利用效率低于农业系统 ,且Ｎ肥生产成本较高 ,易造成环境中多余Ｎ素的污染 ,所以需要更有效的经营管理方法。要改进这类方法 ,则必须很好地理解全球各种森林生态系统的Ｎ素循环和Ｎ素可利用性[3 1] 。可利用性养分 (ａｖａｉｌａｂｌｅｎｕｔｒｉｅｎｔ)是指土壤中易被植物吸收同化的养分元素或化合物的数量[4 0 ] ,可以理解为植物利用土壤中易吸收和…     

Die Nützlingsschonende Schädlingsbekämpfung und ihre Beziehung zur Taxonomie der Nützlinge und Schädlinge

Summary The author being in charge of the international study group for integrated control of the International Committee for Biological Control (C.I.L.B.) was invited to read a lecture on the subject mentioned above at the international meeting of the study group for taxonomy of the C.I.L.B. at Zürich. First the factors that gave rise to an increased interest for the integrated control in W. Europe are dealth with. Next the differences in the occurence of noxious insects and spidermites in neglected and well kept orchards in the Netherlands are discussed in connection with their original causes (culture measures, chemical control, manuring). The question if every well kept plantation will be permanently threatened by specific pests is broached. According to the author chemical control will not give a lasting solution of the problem of pest control (disturbance of the biocoenosis, development of resistant populations of the noxious organisms) nor does biological control in the temperate regions. In some cases however the integrated pest control appears to give promising results in this respect. The possibilities of integrated control in the Netherlands and the fundamental problems connected with it are studied by a group of researchworkers. For these investigations a reliable identification of the harmful and useful organisms is of primary importance as well as a thorough knowledge of the excisting in terrelations in the biocoenosis of the biotop in which the harmful organism is living. In this field however many taxonomic difficulties are met with. Some of these problems met by the dutch researchworkers in connection with the identification of harmful and useful organisms are dealt with.      

Towards an understanding of the dynamics of compost N in the soil-plant-atmosphere system using 15N tracer

Aims

The principal aim of the present review is to synthesize and evaluate published information on the N fertilizer value of composts, and their effect on the utilization of conventional N fertilizers by crops.

Methods

We have examined the literature where the dynamics of N in the soil-plant-atmosphere continuum are traced using composts that were either artificially enriched in the ¹⁵N stable isotope (in units of atom % ¹⁵N excess) or had a natural ¹⁵N abundance (δ¹⁵N in units of ‰ or per mil) due to isotope discrimination processes that occur during composting. The methods used to produce artificially-enriched composts and to test uniformity of labelling are reviewed.

Results

Limited data show that composts are generally inferior sources of N for crops compared with their raw materials due to a lower N mineralization capacity. Immobilization of fertilizer N increases in compost-amended soils and may reduce recovery by a crop, but fertilizer N losses are reduced overall. However, co-application of compost and urea should be avoided due to the risk of increased NH₃ volatilization due to the action of compost-derived urease. High annual rates of compost application can exacerbate environmental problems including nitrate contamination of groundwater.

Conclusions

Efforts are required to improve the N fertilizer value of composts by minimizing NH₃ volatilization losses during composting. More attention should also be given to the use of the natural ¹⁵N abundance of compost as a tracer.     

N:P化学计量学在生态学研究中的应用

化学计量学很早就被应用于生态学研究中,但长期以来几乎被生态学家所忽视.近年来,由于认识到化学计量学研究可以把生态实体的各个层次在元素水平上统一起来,因此元素化学计量学成为近年来新兴的一个生态学研究领域.氮磷作为植物生长的必需矿质营养元素和生态系统常见的限制性元素,在植物体内存在功能上的联系,二者之间具有重要的相互作用.近年来由于人类活动的强烈影响,这两种元素的循环在速度和规模上都发生了前所未有的改变,导致一系列环境问题的出现,因此N:P化学计量学研究就显得极为重要.本文论述了N:P化学计量学在物种、群落、生态系统等各层次的应用现状,同时从分子生物学角度分析了应用N:P化学计量学的可行性,并指出了N:P化学计量学研究的应用前景和存在的缺陷.     

东北蕨类植物的分类研究

通过研究现有标本,考证即往文献,本文就东北蕨类植物疑难种类发表了自己的分类见解。指出了既往文献的某些错误;描述了这些种类的鉴别性特征及与其近亲种的区别;提出了二个命名新组合。更多还原     

15N2 measurement of nitrogen fixation by legumes and actinorhizals: theory and practice

A gas-tight chamber has been constructed to calibrate the ¹⁵N isotope dilution method against direct ¹⁵N₂ measurements. The theoretical basis for such estimates is given, and the practical problems associated with the experiments are discussed.     

For holistic control of reactive N: Regional, national and global perspectives

Reactive N is closely related to the global issues of climate change and regional pollutions. Nitrous oxide (N2O), the fourth important gas among greenhouse gases, is produced as an intermediate in nitrification and denitrification processes. As methane (CH4) is the end product in the anoxic decomposition of organic materials, mitigation options of N2O emission are different from those of CH4 emission. Nitrate is another reactive N bringing about the eutrification of aqueous environments and the hazard of drinking water. Mitigation of NO3 problem also relates closely to the N2O emission. Therefore, holistic approaches are necessary for solving the problems of Earth warming and environmental eutrification by reactive N at the same time. In this paper, the deforestation in the tropics, and the present situations of food supply and sustainable agriculture in Japan are re-evaluated in terms of N2O emission and NO3 discharge from the agricultural sector. The magnitude of N2O emission by deforestation in the tropics may fall within the similar order of magnitude by N fertilization. As more N is imported as foods and fodder than the amount of fertilized N in Japan, more attention should be paid to the phases of their consumption and waste treatment. Sole attention to the production stage is not enough for the total mitigation of various environmental problems by reactive N in relation to agriculture. Parameters holistically evaluating the impact of reactive N on the Earth and respective regions are urgently necessary.     

For holistic control of reactive N: Regional, national and global perspectives

Reactive N is closely related to the global issues of climate change and regional pollutions. Nitrous oxide (N2O), the fourth important gas among greenhouse gases, is produced as an intermediate in nitrification and denitrification processes. As methane (CH4) is the end product in the anoxic decomposition of organic materials, mitigation options of N2O emission are different from those of CH4 emission. Nitrate is another reactive N bringing about the eutrification of aqueous environments and the hazard of drinking water. Mitigation of NO3 problem also relates closely to the N2O emission. Therefore, holistic approaches are necessary for solving the problems of Earth warming and environmental eutrification by reactive N at the same time. In this paper, the deforestation in the tropics, and the present situations of food supply and sustainable agriculture in Japan are re-evaluated in terms of N2O emission and NO3 discharge from the agricultural sector. The magnitude of N2O emission by deforestation in the tropics may fall within the similar order of magnitude by N fertilization. As more N is imported as foods and fodder than the amount of fertilized N in Japan, more attention should be paid to the phases of their consumption and waste treatment. Sole attention to the production stage is not enough for the total mitigation of various environmental problems by reactive N in relation to agriculture. Parameters holistically evaluating the impact of reactive N on the Earth and respective regions are urgently necessary.     

Recent Progress in First Principles O(N) Methods

Abstract

We describe recent progress in developing practical first principles methods for which the computer effort is proportional to the number of atoms: linear scaling or O(N) methods. It is shown that the locality property of the density matrix gives a general framework for constructing such methods. We then outline some of the main technical problems which must be solved in order to develop a practical O(N) method based on density functional theory and the pseudopotential method. Recent progress in solving these problems is presented, and we show that the spatial cut-off distances needed to achieve good accuracy are small enough to make the calculations feasible. Parallel implementation of the O(N) methods in the CONQUEST code is outlined, and it is shown that the code exhibits excellent linear-scaling behaviour on test systems of several thousand atoms. It is pointed out that the most important remaining problem concerns the optimal strategy for seeking the ground state. It is argued that there are three different mechanisms of ill-conditioning which cause present search methods to be inefficient, and some partial solutions are suggested.     

Conservative N cycling despite high atmospheric deposition in early successional African tropical lowland forests

Plant and Soil - Many applied disciplines have recognized problems related to the practice of data analysis within their own communities. Some of them have even declared the existence of a...     

Mango: multiple alignment with N gapped oligos

Multiple sequence alignment is a classical and challenging task. The problem is NP-hard. The full dynamic programming takes too much time. The progressive alignment heuristics adopted by most state-of-the-art works suffer from the "once a gap, always a gap" phenomenon. Is there a radically new way to do multiple sequence alignment? In this paper, we introduce a novel and orthogonal multiple sequence alignment method, using both multiple optimized spaced seeds and new algorithms to handle these seeds efficiently. Our new algorithm processes information of all sequences as a whole and tries to build the alignment vertically, avoiding problems caused by the popular progressive approaches. Because the optimized spaced seeds have proved significantly more sensitive than the consecutive k-mers, the new approach promises to be more accurate and reliable. To validate our new approach, we have implemented MANGO: Multiple Alignment with N Gapped Oligos. Experiments were carried out on large 16S RNA benchmarks, showing that MANGO compares favorably, in both accuracy and speed, against state-of-the-art multiple sequence alignment methods, including ClustalW 1.83, MUSCLE 3.6, MAFFT 5.861, ProbConsRNA 1.11, Dialign 2.2.1, DIALIGN-T 0.2.1, T-Coffee 4.85, POA 2.0, and Kalign 2.0. We have further demonstrated the scalability of MANGO on very large datasets of repeat elements. MANGO can be downloaded at http://www.bioinfo.org.cn/mango/ and is free for academic usage.     

For holistic control of reactive N: Regional,national and global perspectives

Reactive N is closely related to the global issues of climate change and regional pollutions. Nitrous oxide (N₂O), the fourth important gas among greenhouse gases, is produced as an intermediate in nitrification and denitrification processes. As methane (CH₄) is the end product in the anoxic decomposition of organic materials, mitigation options of N₂O emission are different from those of CH₄ emission. Nitrate is another reactive N bringing about the eutrification of aqueous environments and the hazard of drinking water. Mitigation of NO₃ problem also relates closely to the N₂O emission. Therefore, holistic approaches are necessary for solving the problems of Earth warming and environmental eutrification by reactive N at the same time. In this paper, the deforestation in the tropics, and the present situations of food supply and sustainable agriculture in Japan are re-evaluated in terms of N₂O emission and NO3 discharge from the agricultural sector. The magnitude of N₂O emission by deforestation in the tropics may fall within the similar order of magnitude by N fertilization. As more N is imported as foods and fodder than the amount of fertilized N in Japan, more attention should be paid to the phases of their consumption and waste treatment. Sole attention to the production stage is not enough for the total mitigation of various environmental problems by reactive N in relation to agriculture. Parameters holistically evaluating the impact of reactive N on the Earth and respective regions are urgently necessary.

     

For holistic control of reactive N: Regional,national and global perspectives

Reactive N is closely related to the global issues of climate change and regional pollutions. Nitrous oxide (N₂O), the fourth important gas among greenhouse gases, is produced as an intermediate in nitrification and denitrification processes. As methane (CH₄) is the end product in the anoxic decomposition of organic materials, mitigation options of N₂O emission are different from those of CH₄ emission. Nitrate is another reactive N bringing about the eutrification of aqueous environments and the hazard of drinking water. Mitigation of NO₃ problem also relates closely to the N₂O emission. Therefore, holistic approaches are necessary for solving the problems of Earth warming and environmental eutrification by reactive N at the same time. In this paper, the deforestation in the tropics, and the present situations of food supply and sustainable agriculture in Japan are re-evaluated in terms of N₂O emission and NO3 discharge from the agricultural sector. The magnitude of N₂O emission by deforestation in the tropics may fall within the similar order of magnitude by N fertilization. As more N is imported as foods and fodder than the amount of fertilized N in Japan, more attention should be paid to the phases of their consumption and waste treatment. Sole attention to the production stage is not enough for the total mitigation of various environmental problems by reactive N in relation to agriculture. Parameters holistically evaluating the impact of reactive N on the Earth and respective regions are urgently necessary.     

Novel Genotypes of H9N2 Influenza A Viruses Isolated from Poultry in Pakistan Containing NS Genes Similar to Highly Pathogenic H7N3 and H5N1 Viruses

The impact of avian influenza caused by H9N2 viruses in Pakistan is now significantly more severe than in previous years. Since all gene segments contribute towards the virulence of avian influenza virus, it was imperative to investigate the molecular features and genetic relationships of H9N2 viruses prevalent in this region. Analysis of the gene sequences of all eight RNA segments from 12 viruses isolated between 2005 and 2008 was undertaken. The hemagglutinin (HA) sequences of all isolates were closely related to H9N2 viruses isolated from Iran between 2004 and 2007 and contained leucine instead of glutamine at position 226 in the receptor binding pocket, a recognised marker for the recognition of sialic acids linked α2–6 to galactose. The neuraminidase (NA) of two isolates contained a unique five residue deletion in the stalk (from residues 80 to 84), a possible indication of greater adaptation of these viruses to the chicken host. The HA, NA, nucleoprotein (NP), and matrix (M) genes showed close identity with H9N2 viruses isolated during 1999 in Pakistan and clustered in the A/Quail/Hong Kong/G1/97 virus lineage. In contrast, the polymerase genes clustered with H9N2 viruses from India, Iran and Dubai. The NS gene segment showed greater genetic diversity and shared a high level of similarity with NS genes from either H5 or H7 subtypes rather than with established H9N2 Eurasian lineages. These results indicate that during recent years the H9N2 viruses have undergone extensive genetic reassortment which has led to the generation of H9N2 viruses of novel genotypes in the Indian sub-continent. The novel genotypes of H9N2 viruses may play a role in the increased problems observed by H9N2 to poultry and reinforce the continued need to monitor H9N2 infections for their zoonotic potential.     

Methodology of biological thought in works of V. N. Beklemisheva (1890-1862)

During his work in Perm University (1918-1932) Vladimir Nikolaevich Beklemishev created theoretical and methodological foundations for the concepts of constructive morphology and structure of the living cover of the Earth. His conclusions about topical problems of general biology are still valuable for biological thinking.     

Research of the academician I. N. Bulankin on problems of protein chemistry

The article presents an information about scientific researches on the problem of chemical properties and structure of proteins, which were carried out intensively by the biochemists of Kharkiv State University in 30-50 years of XX cent., headed by I. N. Bulankin, academician of Ukrainian Academy of Sciences. This researches dealt with the processes of proteolysis and protein denaturation, the peculiarities of globular and fibrilliar proteins behavior in solution, the properties of complexes with proteins and nucleic acids, etc. The historic analysis of origin and development of this scientific problem at the biochemistry chair of the university and its gradual replacement by researches with other biochemical problems has been carried out. The data concerned with the general situation in the field protein structure of estimation at the world and home biochemistry are cited too. In connection with the above presented the authors give the grounded conclusions about the importance of the scientific researches carried out by I. N. Bulankin as well as about.