25 resultados para Commodity exchanges

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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A new model accounting for both turbulence and sea state effects has been proposed in this paper to describe momentum, heat and moisture exchanges through air-sea interface. While long wave components mainly change air flow profile, short wave components

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In this paper, a ground hydrologic model(GHM) is presented in which the vapor, heat and momentum exchanges between ground surface covers (including vegetation canopy) and atmosphere is described more realistically. The model is used to simulate three sets of field data and results from the numerical simulation agree with the field data well. GHM has been tested using input data generated by general circulation model (GCM) runs for both the North American regions and the Chinese regions, The results from GHM are quite different from those of GHMs in GCMs. It shows that a more active concerted effort on the land surface process study to provide a physically realistic GHM for predicting the exchange between land and atmosphere is important and necessary.

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改进了适合于高寒草甸生态系统的陆地生态圈模式,分析了模式中温度变化与水分运动分层的物理原因,说明了气候状况对地表面能量交换的影响,给出了净辐射和蒸散量新的计算方法,提出了有很差分计算中具有二阶精度的Euler隐式格式,介绍了中国科学院海北高寒草甸生态站的气候概况和野外观测情况。最后利用本模式对高寒草甸生态站地区的土壤-植被-大气间水热交换过程进行了数值模拟,模拟值与实测值吻合较好。

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A novel cadmium-inducible metallothionein (MT) gene (Tpig-MT1) was cloned and sequenced from the ciliate Tetrahymena pigmentosa. The number of deduced amino acids is 118. The polypeptide possesses CCC and CC clusters characteristic of typical Tetrahymena Cd-inducible MTs. The structure of Tpig-MT1 is different from the reported Cd-MT in T. pyriformis, T. thermophila and T. pigmentosa. Tpig-MT1 contains two intragenic tandem repeats with 72.9% identity described as Tpig-MT1 (repeat A1) and Tpig-MT1 (repeat A2). The transcriptional response of Tpig-MT1 gene to different heavy metals (Cd, Cu, Zn, Hg, Pb) and oxidative stress (H2O2) was measured using real-time quantitative PCR. The results showed that the gene was quickly induced (1 h) by the five heavy metals and the order of expression level was Hg>Pb>Cd>Cu>Zn. The induction effect of H2O2 was 5-fold after about 15 min, but soon decreased to a non-significant level (30 min). The genetic diversity of Tetrahymena MT genes is discussed in relation to the unique structure of the Tpig-MT1 gene and other reported Cd-MT isoforms. (C) 2008 Elsevier B.V. All rights reserved.

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Data of classification, origin, pathway and environmental impacts of invasive alien micro-organisms, invertebrates, amphibians and reptiles, fish, birds, mammals, weeds, trees, and marine organisms in terrestrial, aquatic and marine ecosystems of China, were analyzed, based on literature retrieval, field survey and consultation. Some 283 invasive alien species were recorded in China, including 19 invasive alien micro-organisms, 18 aquatic plants, 170 terrestrial plants, 25 aquatic invertebrates, 33 terrestrial invertebrates, 3 amphibians and reptiles, 10 fish, and 5 mammals. Of the invasive alien species, 55.1% originated from North and South America, 21.7% from Europe, 9.9% from Asia, 8.1% from Africa and 0.6% from Oceania. Many institutions and individuals in China lack adequate knowledge of ecological and environmental consequences caused by invasive alien species, with some ignorance of the dangerous invasion in the introduction of alien species. For instance, 50.0% of invasive alien plants were intentionally introduced as pasture, feedingstuff, ornamental plants, textile plants, medicinal plants, vegetables, or lawn plants, 25% of alien invasive animals were intentionally introduced for cultivation, ornament, or biological control, In addition, more efforts are being made in the introduction of alien species, and little attention is paid on the management of introduced alien species, which may cause their escape into natural environment and potential threats to the environment. There were also gaps in quarantine system in China. All microorganisms were unintentionally introduced, through timber, seedling, flowerpot, or soil; 76.3% of alien invasive animals invaded through commodity or transportation facility because of the failure of quarantine. Therefore, quarantine measures should be strictly implemented; and meanwhile the intentional introduction of alien species should be strictly managed and a system of risk assessment should be implemented.

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Immunoglobulin light chain cDNA sequences of a perciform fish, the mandarin fish Siniperca chuatsi were amplified from head kidney mRNA by reverse transcription (RT)-PCR and RACE methods using degenerated primer and gene specific ones. In cDNA sequences of the VL region, nucleotide exchanges were present mainly within CDRs, although a lesser degree of variability was also found in FRs. Moreover, the length of CDRI and CDR3 in the mandarin fish is shorter than in most other fish species. In the middle of S. chuatsi CL region, a microsatellite sequence (AGC)(6-8) was found, which is also present in another perciform species, the spotted wolffish (Anarhichas minor). The comparison of amino acid sequence of the mandarin fish CL domain with those of other vertebrates showed the highest degree of similarity of 94.5% to the spotted wolffish, while the similarity with rainbow trout (Oncorhynchus mykiss) Ig L1 (62.7%) and channel catfish (Ictalurus punctatus) Ig LG (55.9%) isotypes is also higher. However, there is only 50% identity in the VL regions between the mandarin fish and the wolffish. The sequence similarity of the mandarin fish CL domain with those of higher vertebrate did not readily allow it to be classified as kappa or lambda isotype. The phylogenetic analyses also demonstrated that the CL genes of the mandarin fish and most other teleost fish cluster as a separate branch out of the mammal kappa and lambda branches. (C) 2003 Elsevier B.V. All rights reserved.

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The existing methods for the discrimination of varieties of commodity corn seed are unable to process batch data and speed up identification, and very time consuming and costly. The present paper developed a new approach to the fast discrimination of varieties of commodity corn by means of near infrared spectral data. Firstly, the experiment obtained spectral data of 37 varieties of commodity corn seed with the Fourier transform near infrared spectrometer in the wavenurnber range from 4 000 to 12 000 cm (1). Secondly, the original data were pretreated using statistics method of normalization in order to eliminate noise and improve the efficiency of models. Thirdly, a new way based on sample standard deviation was used to select the characteristic spectral regions, and it can search very different wavenumbers among all wavenumbers and reduce the amount of data in part. Fourthly, principal component analysis (PCA) was used to compress spectral data into several variables, and the cumulate reliabilities of the first ten components were more than 99.98%. Finally, according to the first ten components, recognition models were established based on BPR. For every 25 samples in each variety, 15 samples were randomly selected as the training set. The remaining 10 samples of the same variety were used as the first testing set, and all the 900 samples of the other varieties were used as the second testing set. Calculation results showed that the average correctness recognition rate of the 37 varieties of corn seed was 94.3%. Testing results indicate that the discrimination method had higher precision than the discrimination of various kinds of commodity corn seed. In short, it is feasible to discriminate various varieties of commodity corn seed based on near infrared spectroscopy and BPR.

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在全球变化背景下,森林生态系统CO2和H2O交换过程已经成为国际研究的前沿问题。本研究以长白山阔叶红松林为研究对象,利用基于生理生态学过程的多层模型,考虑了混交林中不同树种的生物量、冠层高度和厚度,对冠层及生态系统尺度的碳水通量进行了详细模拟及分析,同时用涡动相关实测数据对模拟结果进行检验,并模拟和预测了阔叶红松林生态系统碳水收支对气候变化的响应,以期为我国研究区域甚至更大尺度碳水平衡的时间和空间格局特征提供模型储备。本文的主要结论如下: 1)长白山阔叶红松林主要优势树种红松、紫椴、水曲柳、色木槭和蒙古栎的生理生态学参数(初始量子效率α、光饱和时的最大净光合作用速率Pmax、最大Rubisco催化反应速率Vcmax、CO2饱和时的最大净光合作用速率Jmax)有着明显且不同的季节变化。6、8月的α值较大,Pmax、Vcmax和Jmax的最大值也出现在6—8月,而5、9月的各项参数值均较小。 2)对阔叶红松林冠层结构的观测,发现各树种在冠层中所处位置有明显差异。假设各树种水平分布均匀,以各树种的冠高、冠厚和叶片生物量为依据,将冠层垂直分为20层,模拟出各层各树种的CO2和H2O通量。这与传统的假设各树种垂直均匀分布相比,更加符合阔叶红松林的实际群落结构。 3)长白山阔叶红松林的能量平衡比EBR为0.800,居于国际同类观测的中上水平,涡相关观测数据较为可靠。CO2和H2O通量有明显日变化,夜间值较小且变化平缓,白天值呈单峰形的日变化。对2003—2007年生长季的模拟结果分析表明,CO2和H2O通量模拟值与涡相关实测值的回归线斜率分别为0.935和0.875,截距为-0.0136 mg•m-2•s-1和13.7 W•m-2,相关系数为0.655和0.622(n=30107);CO2通量模拟和实测的平均值分别为-0.138和-0.134 mg•m-2•s-1,模型高估了2.99%;H2O通量模拟和实测的平均值分别为88.5和85.4 W•m-2,模型高估了3.63%,模拟效果较好。从季节变化来看,生长季初、末期(5月和9月)CO2和H2O通量较小,生长旺盛期(6—8月)通量值较高。CO2和H2O通量受环境因子的综合影响,其中,辐射和气温是主要限制因子。 4)对模型的主要参数和环境因子的敏感性分析表明,CO2通量对a1 (气孔导度的参数)、Vcmax、Ca (大气CO2浓度)变化的响应较强,而H2O通量对a1、LAI (叶面积指数)、Ta (气温)变化的响应较强。CO2通量对Ca的变化最为敏感,而H2O通量对其它环境因子的响应程度均高于CO2通量。与将冠层分为20层的方法相比,5层方法(Gaussion五点积分法)得到的碳吸收量和蒸发散量分别低估了25.3%和11.1%。这两种分层方法产生的差异,主要来自于不同层的辐射吸收和权重分配。

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In protein sequence alignment, residue similarity is usually evaluated by substitution matrix, which scores all possible exchanges of one amino acid with another. Several matrices are widely used in sequence alignment, including PAM matrices derived from homologous sequence and BLOSUM matrices derived from aligned segments of BLOCKS. However, most matrices have not addressed the high-order residue-residue interactions that are vital to the bioproperties of protein.With consideration for the inherent correlation in residue triplet, we present a new scoring scheme for sequence alignment. Protein sequence is treated as overlapping and successive 3-residue segments. Two edge residues of a triplet are clustered into hydrophobic or polar categories, respectively. Protein sequence is then rewritten into triplet sequence with 2 · 20 · 2 = 80 alphabets. Using a traditional approach, we construct a new scoring scheme named TLESUMhp (TripLEt SUbstitution Matrices with hydropobic and polar information) for pairwise substitution of triplets, which characterizes the similarity of residue triplets. The applications of this matrix led to marked improvements in multiple sequence alignment and in searching structurally alike residue segments. The reason for the occurrence of the ‘‘twilight zone,’’ i.e., structure explosion of lowidentity sequences, is also discussed.

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A fully consistent relativistic continuum random phase approximation (RCRPA) is constructed, where the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single-particle Green's function technique. The full consistency of the calculations is achieved that the same effective Lagrangian is adopted for the ground state and the excited states. The negative energy states in the Dirac sea are also included in the single-particle Green's function in the no-sea approximation. The currents from the vector meson and photon exchanges and the Coulomb interaction in RCRPA are treated exactly. The spin-orbit interaction is included naturally in the relativistic frame. Numerical results of the RCRPA are checked with the constrained relativistic mean-field theory. We study the effects of the inconsistency, particularly the currents and Coulomb interaction in various collective multipole excitations.

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A chiral constituent quark model approach, embodying s- and u-channel exchanges, complemented with a Reggeized treatment for the t channel is presented. A model is obtained allowing data for pi(-)p ->eta n and gamma p ->eta p to be described satisfactorily. For the latter reaction, recently released data by the CLAS and CBELSA/TAPS Collaborations in the system total energy range 1.6 less than or similar to W less than or similar to 2.8 GeV are well reproduced by the inclusion of Reggeized trajectories instead of simple. and. poles. The contribution from "missing" resonances, with masses below 2 GeV, is found to be negligible in the considered processes.

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为满足 2 1世纪中国对粮食的需求 ,提出“发展东部 ,提高中部 ,开发西部”的粮食生产战略布局 ,就是在东部平原区发展产业化粮食生产 ,使之成为中国优质商品粮食主要生产基地 ;在中部高原区要大力治理水土流失 ,提高粮食生产的环境质量 ,从而提高粮食产量水平 ;在西部高寒及荒漠区要充分开发光能、土、水资源优势 ,进一步开发高寒农业与绿洲农业的粮食生产潜力