新疆奎屯河流域枯季径流频率分布选型与计算

枯水径流频率计算对于水资源评价、环境水利及工程水文分析有重要的现实意义。文中依据奎屯河流域三条主要河流1959-2006年48年径流序列资料,采用PPCC检验法对我国常用的5种水文频率分布线型进行检验,以选择适合奎屯河流域的最优线型。结果表明:奎屯河流域内三条最大的河流的代表性水文站最小月枯水序列和各时段枯水序列的枯水径流频率分布都是以P-Ⅲ型曲线最优,但流域内其它个别水文站也有以其它线型最优。最后对三条主要河流最小月和最小3个月枯水径流频率采用P-Ⅲ型曲线进行了计算,得出不同保证率的枯水径流。     

果蔬运输保鲜蓄冷剂的研制

研究了5种常见蓄冷剂中不同主储能剂及其复配后在降温过程中的温度变化规律,结果表明,蔗糖和丙三醇溶液在-5℃以上降温速度较快,温度波动较小,稳定性良好,适合作为果蔬蓄冷剂的主储能剂材料;二者以6%的浓度溶液1∶1比例复配后作主储能剂蓄冷效果最佳,可对不耐高温的果蔬在运输中起到降温保鲜的作用。     

Experimental Analysis on the Deformation of Sandstone underPore Pressure and Constant Time

In order to discuss the deformation characteristics of rock mass under different water levels changing between 145 and 175 meter in the Three Gorges reservoir area, an experiment was carried out for the studying sandstone deformation under the conditions of three different axial stresses(σ1=55.54,34.18,12.82 MPa), two cyclic pore pressures(Pmin=2 MPa,Pmax=6 MPa) and two kinds of constant time(the upper limit time and the lower limit time(ΔT=120,240 s).With ε1-T curves and p-T curves, as well as p-ε1  hysteresis curves, it was found that the curves were continuous sine wave-shaped curves.At first, the strain decreased with loading pore pressure.And then, it decreased to valley value with pore pressure at stable upper limit.Next, it increased with unloading pore pressure and increased to peak value with pore pressure at stable lower limit.The p-ε1  hysteresis curves of the sandstone had two typical stages.And one was caused by the closure of some primary pores and crack under increasing compaction, in which the strain did not form obviously hysteresis curves, and the other was pore pressure coupling stage which showed obvious hysteresis curve in form of the anti-clockwise from the dispersed to the dense.In addition, Δε-n curves in four sections (loading, unloading, steady upper limit, steady lower limit) of p-ε1 curves were compared and respectively ananlyzed in the condition of various axial stress and different constant time .     

不同水肥条件下白羊草光合生理生态特征研究Ⅱ.光响应曲线

为揭示黄土丘陵区乡土草种白羊草(Bothriochloa ischaemum (L.) Keng.)在不同水肥供应条件下的光合生理特征,本研究采用盆栽控制实验,比较研究了白羊草在2种水分水平(HW-80%FC和LW-40FC%)和3种养分(CK,P和NP)处理下的光合光响应曲线特征。结果表明:非直角双曲线模型能很好的拟合白羊草光响应曲线。充分供水条件下(HW),土壤NP营养提高了白羊草最大净光合速率(P′_max),降低了暗呼吸消耗(R_d)并且保持较低的光合补偿点(LCP)和较高的光饱和点(LSP),表明NP营养有利于提高白羊草对光照的广幅适应能力和光合潜力。水分胁迫条件下(LW),P处理显著提高了白羊草P′_max,其表观量子效率(a)和LCP也相对较高,表明施磷将有利于提高干旱条件下白羊草的光合能力。     

荧光定量PCR检测牛性别相关基因DAX1表达的标准质粒和标准曲线的构建

本研究根据GenBank中登录的剂量敏感的性别反转－先天性肾上腺发育不良基因1(dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1,DAX1)设计引物,构建包含DAX1基因cDNA片段的质粒,作为中国荷斯坦牛DAX1基因mRNA定量检测的标准品,建立了DAX1基因mRNA表达实时荧光定量PCR检测方法。结果表明,该方法特异性好,检测灵敏度达102拷贝,线性范围为102～106拷贝,阈值循环数(Ct)与PCR体系中起始模板量的对数值间有着良好的线性关系(r=0.99975),扩增效率高(E=100%),可以作为检测牛DAX1基因mRNA定量检测方法。     

不同种植模式蔗茎伸长特性分析

在大田条件下,以甘蔗品种新台糖22为试验材料,采用Logistic方程拟合了窄行宽株等行距、宽行窄株等行距、宽窄行窄株距和宽窄行宽株距4种种植模式下蔗茎的伸长特性。结果表明:(1)Logistic方程能够可靠的估计不同种植模式蔗茎伸长的进程。(2)不同种植模式蔗茎伸长的潜力值存在一定的差异,以宽窄行窄株距种植模式最大,且该差异的产生体现在蔗茎伸长持续时间或伸长速率上。(3)不同种植模式蔗茎伸长快增期的持续时间最短,但贡献率最大。因此,选择合理的种植模式和加强快增期的田间管理对蔗茎伸长具有重要的意义。     

随机理论方法在水文模拟中的应用

水文模型中的参数是对实测资料进行分析研究的基础上通过优选得到的,因此存在一定的随机性。针对模型参数的随机性问题,文章以Nash模型为基础,应用随机理论对具有随机系数的汇流计算方法进行研究。将参数k作为随机变量引入到了Nash模型中,建立了具有随机系数的汇流模型,并对模型参数分别服从正态分布和Gamma分布进的情况推导出了随机S曲线的均值和方差的一般表达式,将其应用于襄阳-皇庄的汇流计算中,得到了较好的结果。该方法能为实际应用中估计各种防洪决策提供依据。     

Application timing and adjuvant type affected saflufenacil efficacy on selected broadleaf weeds

Saflufenacil is a new herbicide being developed for pre-plant burndown and pre-emergence broadleaf weed control in field crops, including maize, soybean, sorghum and wheat. Field experiments were conducted in 2007 and 2008 in northeast Nebraska, USA to describe dose-response curves of saflufenacil applied in mid (early post-emergence, EPOST) and late May (late post-emergence, LPOST) with several adjuvants for spring emerging broadleaf weed control. Dose-response curves based on log-logistic model were utilized to determine the ED₉₀ values (effective dose that provides 90% weed control efficacy) for Convolvulus arvensis, Lactuca serriola, Lamium amplexicaule, Capsella bursa-pastoris, Taraxacum officinale, Thlaspi arvense and Conyza canadensis. In general, weed control efficacy was influenced by application timing and type of adjuvant. EPOST application of saflufenacil resulted better efficacy of saflufenacil compared to LPOST. Addition of spray adjuvants improved efficacy of saflufenacil. For example, 90% control of T. arvense was obtained at EPOST application with 251, 161, 96 and 59 g a.i. ha⁻¹ for saflufenacil applied alone, or tank-mixed with NIS (nonionic surfactant), COC (crop oil concentrate), or MSO (methylated seed oil), respectively. In contrast, the ED₉₀ values with LPOST application were 333, 201, 127 and 79 g a.i. ha⁻¹ for saflufenacil applied alone, or with NIS, COC and MSO, respectively. MSO was the best adjuvant, which provided the most enhancement of saflufenacil. COC was the second best, or similar to MSO, on many weed species. NIS provided the least enhancement of saflufenacil. The ED₉₀ values determined for different broadleaf weed species are within the proposed label dose of saflufenacil.     

土壤水分特征曲线VG模型参数求解对比分析

采用负压计对砂壤土试样进行了土壤水吸力和对应含水量的测量,并分别运用RETC软件和Matlab软件对不同水分处理土壤水分特征曲线VG模型进行了拟合计算,然后将拟合值与实测数据进行对比分析。结果表明,Matlab和RETC软件均可用于土壤水分特征曲线VG模型的参数求解,Matlab软件比RETC软件拟合的误差小,拟合效果明显优于RETC软件,RETC软件对极端干旱区砂石占绝对比重的砂壤土拟合效果不佳。     

浙东白鹅生长曲线及拟合分析

运用Logistic、Gompertz和Von Bertalanffy 3种非线性模型对浙东白鹅0~8周龄的生长曲线进行分析及拟合比较。结果表明,浙东白鹅公、母鹅在3周龄前生长曲线基本一致,之后一直到8周龄公鹅明显高于母鹅;3种曲线模型拟合度均达到0.99以上,其中Gompertz曲线模型在拟合度和预测极限生长量拐点周龄和最大周增重等方面相对较好。进一步分析结果表明,浙东白鹅公鹅的拐点体重高于母鹅,拐点周龄性别间差异不大。本研究对不同性别浙东白鹅的生长模式及其对营养环境的需求进行了初步探讨,为开展浙东白鹅的规模化养殖提供参考。