施钾条件下杂交水稻氮磷养分吸收利用特点

对浙江省金华市郊区石门农场灌溉稻区进行连续4年定位钾肥试验,结果表明,钾素促进氮磷养分向水稻穗部的输入,故在增产的基础上,同不施钾处理比较,施钾后杂交稻氮的总吸收量增加7.1～9.3kg/hm2,利用效率提高3.7～7.1%;磷的总吸收量增加1.0～2.0kg/hm2,利用效率提高2.0～7.7%。同常规稻比较,每季杂交稻氮和磷的平均总吸收量分别高出7.6kg/hm2和1.2kg/hm2;氮和磷的利用效率平均高出3.1kg/kg和34.7kg/kg;在养分的吸收、积累以及利用效率方面表现出明显的生理优势[1]。因此,在杂交水稻的生产实践中,应相对增加钾肥的施入量,从而提高氮肥和磷肥的利用效率。     

不同C/N有机物料对烤烟生长发育和生理特性的影响

试验采用盆栽试验,研究了不同碳氮比的有机物料对烤烟生长发育和生理特性的影响.结果表明,有机物料的碳氮比在20～40之间时,更适合烤烟的生长发育,烤烟干物质积累量可获得最大;C/N=20和C/N=40处理在烤烟生长后期能够显著降低烟叶中的叶绿素含量,从而使得这两个处理比其它处理落黄好;C/N=20处理的硝酸还原酶活性和烟叶中的游离氨基酸含量在旺长中期显著高于其它处理;在圆顶期C/N=20和C/N=40处理的淀粉酶活性显著高于其它处理.     

氮肥施用对黄土高原中部雨养农业区土壤硝态氮分布与累积的影响

黄土高原中部雨养农业区春小麦氮肥试验表明,氮肥施用量对土壤硝态氮的移动深度没有影响,但显著影响土壤硝态氮的含量与累积。连续施氮3年后第3季春小麦收获时,0～200cm土壤剖面中累积大量的硝态氮,其中48.96%～81.38%的总累积量和60.49%～122%的当年净累积量存在于0～110cm土层中。在确定春小麦适宜施氮量时应考虑到0～110cm土层中残留硝态氮的累积量。不施氮和氮磷比例为1:1时,连续施氮三年后土壤硝态氮总累积量最低,数量几乎相等;第3季春小麦收获后较播种时,土壤硝态氮发生亏缺。施氮量为52.5 kgN hm-2时土壤硝态氮的三年总累积率和第3季春小麦当年的净累积率居各处理之首(146.55%和138.21%)。合理的氮磷配比可有效减少土壤硝态氮的累积,不合理的氮磷配比下,低施氮量也会造成土壤硝态氮的大量累积。     

长期定位不同施肥处理的棕壤腐殖酸性质的研究

以长期定位试验土样为材料,对不同施肥处理土壤腐殖质组成及性质进行研究。结果表明:通过施肥提高腐殖质的含量同时能降低胡敏酸E4/E6值,增加了胡敏酸分子的复杂程度。无机肥、有机肥和无机有机肥配施均能增加胡敏酸和胡敏素的含量。土壤不同形态胡敏素含碳量不同,不溶性胡敏素含碳量最多,占总含碳量的.47.6%~57%,铁结合态胡敏素占总含碳量的3.1%~5.7%,粘粒结合态胡敏素占总含碳量的2.0%~3.7%。     

新垦淡灰钙土不同施肥定位试验初报

淡灰钙土是宁夏重点开发利用的耕地资源。针对新垦淡灰钙土土壤养分含量十分贫乏的问题,采取田间定位试验的方法,研究了新垦淡灰钙土4年不同施肥处理的增产培肥效应,结果表明:单施氮肥、有机肥和氮磷、氮磷锌及氮磷有机肥配施均有显著的增产作用。其中,施N225kg hm-2,较不施肥(对照)平均增产46.9%;施P2O5103.5~207.0kg hm-2,较单施氮肥平均增产31.3%,土壤速效磷提高1~2倍;每公顷第1年增施硫酸锌45kg hm-2的较氮磷配施平均增产7.7%,土壤有效Zn含量连续4年较氮磷配施提高1~1.5倍;增施羊粪11250~22500 kg的较氮磷配施平均增产14.1%,同时,土壤有机质含量较单施化肥提高30%左右。     

不同NPK配置对强筋小麦群体生物量与产量的效应研究

在关中川道灌区以强筋小麦陕253为材料,研究了不同NPK配置对其不同生育期生物产量、群体数量和产量的效应,结果表明提高施肥量可显著增加生物产量、群体数量及产量,处理平均值分别比常规处理增加11.9%~43.6%、4.1%~17.4%和8.3%,其最佳N、P、K配置依次为N135kg hm-2,P2O5和K2O各120kg hm-2、N135kg hm-2,P2O5225kghm-2,K2O120kg hm-2和N225kg hm-2,P2O5和K2O各120kg hm-2。在目前常规投肥水平下适度增加钾肥有利于生物产量的显著提高,增加磷肥和钾肥有利于群体数量的提高,增施氮钾肥有显著的增产效果。产量的最佳NPK配比较常规处理增产19.1%,其增加养分的平均产量4.44 kg kg-1,比各处理平均养分产量高1.6倍。     

计算K（≥2）序线性递归N方程组的一种有效并行方法

本文提出计算K(≥2)序线性递归N方程组的一种有效并行方法,当k<相似文献   

不同施氮量下北方稻田一次与分次施氮对水稻产量的影响

设计了适量和过量总施氮量下的一次和分次施氮的田间试验,研究了不同施肥方式对山西半干旱地区肥力水平较低的盐渍型水稻土水稻产量的影响.结果表明,适宜氮量(N 198 kg hm-2)下,水稻插秧前基肥一次性施氮较分三次在不同生育期施氮稻谷平均增产达10%;但过量施氮下,一次性基肥施氮较分三次施用平均减产6.6%.总施氮量小于适宜施氮量时,基肥一次性施氮较分三次施用平均增产则达到30%.插秧前基肥一次性施氮与基肥和分蘖初期分两次施氮相比,稻谷产量无明显差异.这说明插秧前和分蘖初期是该地水稻的有效施肥期.在不施磷肥或磷肥做基肥一次施用而氮肥分次施用的情况下,基肥氮磷施用比例也影响所施用氮肥的肥效;因此,就所试验的肥力较低的盐渍型水稻土来说,可以实行在减量施氮下的插秧前基肥一次性施氮,而不需要追施氮肥,并且在施P205130kg hm-2的条件下,总施氮190kg hm-2即可满足高产,因而可以减少习惯施氮量的1/3.     

不同氮、磷、钾肥用量对玉米源、库干物质积累动态变化的影响

本研究采用田间小区的试验方法研究了不同氮、磷、钾用量下玉米各组分的干物质积累及其随时间的动态变化规律。结果表明,不同氮、磷、钾肥用量下玉米的各组分干物质积累随生育期的延续呈现有规律的动态变化:叶片、茎秆、营养体干物质积累自拔节期后呈直线上升,至灌浆期干物质积累达到最大值,之后便呈缓慢下降趋势;籽粒的干物质积累在灌浆期之前缓慢增加,之后呈直线上升;总生物产量在苗期缓慢增长,中期呈直线上升,到了后期由于营养体干物质的下降以及籽粒干物质的显著上升,也稳定增长。营养体、籽粒干物质和总生物产量的积累随时间的动态变化,均可用Logistic方程Y=a/(1 bexp(ct))来描述;在各个氮、磷、钾处理中,以N240、P225、K240处理各组分干物质积累最大速率较大,出现日期较早。籽粒和总生物产量之间的关系可用回归方程Y=exp(a bx)描述。在氮、磷、钾各用量下,氮以N240、磷以P225、钾以K240处理籽粒产量最高,收获系数最大,因此比较适宜的N、P2O5、K2O用量分别为240、150、240 kg hm-2。     

土壤养分类型与小麦最佳施肥比例及最大施肥量的关系

在同一试验中采用以氮定磷和氮磷等比条件下同步增加氮磷用量的方法,对土壤养分类型与小麦最佳施肥比例和最大施肥量进行了田间试验.试验表明,不同养分类型的土壤种植小麦,均存在平衡与不平衡土壤养分类型和特定的最佳施肥比例,而小麦最大氮磷施用量严重受试验设计方法的影响.田间试验以最佳氮磷施肥比例条件下同步增加用量设计方法确定的最大氮磷用量较为准确,而以氮定磷的试验方法只有其中有一个处理的施肥比例和用量接近小麦最大氮磷用量的情况下,试验结果才接近实际情况.     

Ein Modell desP =N P-problems mit einer positiven Lösung

Zusammenfassung Wir diskutieren die Sprachmittel, die zur Formalisierung des P = N P-Problems in einer naiven Mengenlehre benötigt werden. Die Kategorie der kommutativen, idempotenten Semigruppen verfügt über genügend Struktur, daß diese Formalisierung in ihr vorgenommen werden kann. Sie besitzt also ihr eigenes P = N P-Problem. Für dieses Problem gilt P = N P.

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A model of the P = N P-problem with a positive solution

Summary We discuss the language necessary to give a formalization of the P = N P-question in a Cantor's style set-theory. The internal structure of the category of idempotent, commutative semigroups is rich enough, to carry out this constructions. Hence this category has its own P = N P-question. The answer to this question is: P = N P.

     

A counterexample on continuous coprime factors

In Georgiou and Smith (1992), the following question was raised: Consider a linear, shift-invariant system on L₂[0, ∞). Let the graph of the system have Fourier transform (MN)H² (i.e., the system has a transfer function P=N/M) where M, N are elements of C_A={f∈H^∞: f is continuous on the compactified right-half plane}. Is it possible to normalize M and N (i.e., to ensure |M|²+|N|²=1) in C_A? The author shows by example that this is not always possible     

On dimensionality, sample size, classification error, and complexity of classification algorithm in pattern recognition

This paper compares four classification algorithms-discriminant functions when classifying individuals into two multivariate populations. The discriminant functions (DF's) compared are derived according to the Bayes rule for normal populations and differ in assumptions on the covariance matrices' structure. Analytical formulas for the expected probability of misclassification EPN are derived and show that the classification error EPN depends on the structure of a classification algorithm, asymptotic probability of misclassification P?, and the ratio of learning sample size N to dimensionality p:N/p for all linear DF's discussed and N2/p for quadratic DF's. The tables for learning quantity H = EPN/P? depending on parameters P?, N, and p for four classifilcation algorithms analyzed are presented and may be used for estimating the necessary learning sample size, detennining the optimal number of features, and choosing the type of the classification algorithm in the case of a limited learning sample size.     

Visual Assessment of Clustering Tendency for Rectangular Dissimilarity Matrices

We have an m times n matrix D, and assume that its entries correspond to pair wise dissimilarities between m row objects O_r and n column objects O_c, which, taken together (as a union), comprise a set O of N = m + n objects. This paper develops a new visual approach that applies to four different cluster assessment problems associated with O. The problems are the assessment of cluster tendency: PI) amongst the row objects O_r; P2) amongst the column objects O_c; P3) amongst the union of the row and column objects O_r U O_c; and P4) amongst the union of the row and column objects that contain at least one object of each type (co-clusters). The basis of the method is to regard D as a subset of known values that is part of a larger, unknown N times N dissimilarity matrix, and then impute the missing values from D. This results in estimates for three square matrices (D_r, D_c, D_rUc) that can be visually assessed for clustering tendency using the previous VAT or sVAT algorithms. The output from assessment of D_rUc ultimately leads to a rectangular coVAT image which exhibits clustering tendencies in D. Five examples are given to illustrate the new method. Two important points: i) because VAT is scalable by sVAT to data sets of arbitrary size, and because coVAT depends explicitly (and only) on VAT, this new approach is immediately scalable to, say, the scoVAT model, which works for even very large (unloadable) data sets without alteration; and ii) VAT, sVAT and coVAT are autonomous, parameter free models - no "hidden values" are needed to make them work.     

分子连接性指标对羧酸类疏水常数的研究

采用分子连接性指标研究了105个含有丰富取代基的羟酸分子,指标中考虑了非价、羧酸、不饱和键和杂原子对分子疏水常数的影响。通过多元逐步回归关联得一含有六个指标的方程,发现该类分子的疏水常数与非价的0χP,羧基的ΔχC,以键的Δ2χP和杂原子的1χP、5χC、6χP具有良好的相关性(N=105,S=0.25,F=127.73,R=0.94),并用此模型预测了五个羧酸分子的疏水常数,得到了满意的结果。最后对影响羧酸类分子疏水常数的原因进行了分析。     

The number of N-point digital discs

A digital disc is the set of all integer points inside some given disc. Let D_N be the number of different digital discs consisting of N points (different up to translation). The upper bound D _N = O(N²) was shown recently; no corresponding lower bound is known. In this paper, we refine the upper bound to D_N = O(N), which seems to be the true order of magnitude, and we show that the average D_N = D₁ + D₂ ... D_N)/N has upper and lower bounds which are of polynomial growth in N     

Fast solving method of fuzzy relational equation and itsapplication to lossy image compression/reconstruction

A fast solving method of the solution for max continuous t-norm composite fuzzy relational equation of the type G(i, j)=(R^T□A_i)^T□B_j , i=1, 2, ..., I, j=1, 2, ..., J, where A_i∈F(X)X={x₁, x₂, ..., x_M }, Bj∈F(Y) Y={y₁, y₂, ..., y_N}, R∈F(X×Y), and □: max continuous t-norm composition, is proposed. It decreases the computation time IJMN(L+T+P) to JM(I+N)(L+P), where L, T, and P denote the computation time of min, t-norm, and relative pseudocomplement operations, respectively, by simplifying the conventional reconstruction equation based on the properties of t-norm and relative pseudocomplement. The method is applied to a lossy image compression and reconstruction problem, where it is confirmed that the computation time of the reconstructed image is decreased to 1/335.6 the compression rate being 0.0351, and it achieves almost equivalent performance for the conventional lossy image compression methods based on discrete cosine transform and vector quantization     

Triple positive solutions for some second-order boundary value problem on a measure chain

In this paper, we study the existence of three positive solutions for the second-order two-point boundary value problem on a measure chain,

where f:[t₁,σ(t₂)]×[0,∞)×R→[0,∞) is continuous and p:[t₁,σ(t₂)]→[0,∞) a nonnegative function that is allowed to vanish on some subintervals of [t₁,σ(t₂)] of the measure chain. The method involves applications of a new fixed-point theorem due to Bai and Ge [Z.B. Bai, W.G. Ge, Existence of three positive solutions for some second order boundary-value problems, Comput. Math. Appl. 48 (2004) 699–707]. The emphasis is put on the nonlinear term f involved with the first order delta derivative x^Δ(t).     

碳,氢,氧,氮物系的焓值与燃烧温度

根据函数关系设计出一种表格,任何只含C,H,O,N 4种元素的可燃物质在标准大气压下与氧,空气或者任意比例的氧,氮混合物或化合物按化学计量比进行绝热燃烧时达到的温度都可精确地查得.本表还可用于非绝热燃烧过程的计算.     

Distributed Object Based Design: Vertical Fragmentation of Classes

Processing costs in distributed environments is most often dominated by the network communications required for interprocess communication. It is well known from distributed relational database design research that careful placement of data near the users or processors where it is used is mandatory or system performance will suffer greatly. Data placement in relational database systems is comparatively simple because the data is flat, structured, and passive. Objects are characterized by an inheritance hierarchy (other hierarchies could also be considered including, class composition and execution), unstructured (possibly dynamic data), and contain a behavioral component that defines how the data is accessed by encapsulating it within the object per se. Algorithms currently exist for fragmenting relations, but the fragmentation and allocation of objects is still a relatively untouched field of study.Similar to relations, objects can be fragmented both horizontally and vertically. Vertical fragmentation must minimize application execution time by splitting a class so that all class attributes and methods frequently accessed together are grouped together into a single fragment. This paper adopts a classification of classes into four main models, and contributes by proposing algorithms for vertically fragmenting the four realizable class models consisting of simple or complex attributes combined with simple or complex methods. Vertical fragmentation entails splitting classes into a set of smaller equivalent classes (actually fragments of the class' extent) that can later be placed precisely where they are used. Our approach consists of grouping into a fragment, all attributes and methods of the class frequently accessed together by applications running on either this class, its subclasses, its containing classes or its complex method classes.