m法下的双曲线型p-y曲线

工程中基桩大多处于复杂的成层地基中,鲜有位于单一土层中,从宏观角度出发,引入初始地基比例系数,提出了基于m法的双曲线型p-y曲线。某现场7根试桩地基土非线性显著,实测和理论计算的地面处桩身水平位移水平荷载关系曲线均呈良好的二次抛物线关系,且理论与实测曲线吻合良好,验证了本文p-y曲线模型。地基土非线性对桩身最大弯矩、桩侧地基土压力影响显著,不容忽略。工程实际中采用m法计算基桩最大弯矩值偏小,建议乘以1.05~1.25的系数,以计入地基土非线性影响。     

Tree and fruit traits of progenies from the cross between (Annona cherimola Mill.?×?A. squamosa L.)?×?A. reticulata L. and approaches for the introgression of valuable genes from A. reticulata L.

Atemoya (Annona cherimola Mill. × A. squamosa L) and A. reticulata L. possess several contrasting foliage characteristics. Two hundred and fifty trispecies hybrids of atemoya and A. reticulata were therefore studied to investigate the inheritance of four foliage characteristics. Segregation for leaf colour (green or dark green), leaf angle (erect or drooping), leaf apex shape (rounded or pointed) and time of leaf fall (early or late or intermediate) into discreet phenotypic classes revealed that their inheritance followed simple Mendelian genetics. Based on phenotypes of parents and the segregating population, and the genetic ratios obtained, allelic symbols were assigned to four leaf characteristics. Duplicate dominant gene interaction governed the leaf colour and leaf position. Thus individuals with single or both the dominant genes (A-B-, A-bb, aaB-) produce green colour leaves and those with recessive genes (aabb) dark colour leaves. Likewise erect leaf individuals are C-D-, C-dd, ccD- and those with drooping leaves are ccdd. Further a single gene determined shape of leaf apex that was either rounded (Rr) or pointed (rr). Segregation of progenies for leaf fall into early (J ^E J ^E ), intermediate (J ^E J ^L ) and late (J ^L J ^L ) suggested that codominant alleles were responsible for time of leaf fall. The inheritance studies reported in this paper should guide in Annonaceous fruit breeding for foliage characteristics or could be used as selection criteria for those important traits with which they are associated.     

剪切变形对基桩P-Δ效应的影响

给出了小剪切变形下的基桩P-Δ效应和大剪切变形下支座P-Δ效应计算的杆单元刚度矩阵方程。假定杆单元弯曲变形位移函数为三次幂函数,剪切变形函数为线性函数,根据有限元法一般原理,推导了一种同时计入竖向力径向剪切分力剪切变形和水平力剪切变形的P-Δ效应杆单元刚度方程,推导了一种仅计入竖向力径向剪切分力剪切变形而忽略水平力剪切变形的P-Δ效应杆单元刚度方程,推导了一种仅计入水平力剪切变形而忽略竖向力径向剪切分力剪切变形的P-Δ效应杆单元刚度方程。计入水平力剪切变形而忽略竖向力径向剪切分力剪切变形的P-Δ效应杆单元可良好的模拟支座在大剪切变形下的偏心工作特性,能实时计入其偏心弯矩影响,为实时计入支座偏心特性的结构动静力分析提供了理论支撑。最后通过自编MATLAB程序进行算例分析,结果表明,计入支座大剪切变下的P-Δ效应后,基桩内力位移和地基土压力均显著增大。基桩自身剪切变形对桩身内力位移和地基土压力影响较小,可以忽略。     

Development of a coupling-phase SCAR marker linked to the powdery mildew resistance gene ‘er1’ in pea (Pisum sativum L.)

Pea powdery mildew is one of the major constraints in pea production worldwide, causing severe seed yield and quality loss. The resistance is governed by a single recessive gene er1 in majority of resistant cultivars, but er2 and Er3 have also been reported. The objective of the study was to find out tightly linked sequence characterized amplified regions (SCAR) markers to er1 gene using NILs. A total of 620 random amplified polymorphic DNA (RAPD) markers were screened for length polymorphism between seven sets of NILs. The 880 bp polymorphic band of the tightly linked RAPD marker OPX 04₈₈₀ was cloned, sequenced and a SCAR marker ScOPX 04₈₈₀ was developed. In a population of completely classified 208 F₂ plants (supported by phenotypic data from 208 F_2:3 and 4,390 F_3:4 families) ScOPX 04₈₈₀ was linked at 0.6 cM in coupling phase with er1 gene in the order ScOPX 04₈₈₀–er1–ScOPD 10₆₅₀. ScOPX 04₈₈₀ will correctly differentiate homozygous resistant plants from the susceptible accessions with more than 99 % accuracy. In combination with repulsion phase marker ScOPD 10₆₅₀, ScOPX 04₈₈₀ can help in an error free marker-assisted selection.     

Unreduced 3x gamete formation of allotriploid hybrid derived from the cross of Primula denticulata (4x)?×?P. rosea (2x) as a causal factor for producing pentaploid hybrids in the backcross with pollen of tetraploid P. denticulata

A triploid hybrid, which was obtained from interspecific crosses between tetraploid Primula denticulata (2n = 4x = 44) and P. rosea (2n = 2x = 22), successfully produced 11 plants by backcrossing with pollen of tetraploid P. denticulata. Analysis of ploidy level using flow cytometry and chromosome counting in the 11 BC₁ plants revealed that all progeny had much larger DNA contents and chromosome number than both parents. In this triploid-tetraploid (3x–4x) crossing, progeny was predominantly true or near pentaploid presumably produced by the fertilization between true or near triploid female gamete produced from triploid hybrid and diploid pollen of tetraploid P. denticulata. These results suggest that unreduced (3x) or near triploid female gametes were partially produced by single step meiosis, either first-division restitution or second-division restitution process. The zygotes formed by the fertilization between true or near triploid egg produced by single step meiosis in triploid hybrid and diploid pollen produced by normal meiosis of tetraploid P. denticulata might be the only survivors in embryogenesis.     

苋菜/青梗菜/波菜/油麦菜/生菜周年高效栽培技术模式

为提高土地利用率,增加复种指数,提升蔬菜品质,近年来,笔者通过合理安排蔬菜品种、茬口,集成了一套苋菜/青梗菜/波菜/油麦菜/生菜周年高效栽培模式。