Short-term storage and cryopreservation of Urechis unicinctus (Echiura: Urechidae) sperm

In the present study, attempts were made to preserve Urechis unicinctus sperm at 4°C. Cryopreservation procedures were optimized for various cryoprotectants and freezing rates, equilibration times and dilution ratios. During short‐term storage, the motility of undiluted sperm was extended for 6 days of cold storage,and in 70% and 100% artificial seawater only persisted for 2 and 4 days respectively. The survival rate of undiluted sperm was maintained at a high level accordingly. After cryopreservation, the highest motility and survival rate (41.5±2.2%) were obtained in 15% dimethyl sulphoxide (Me₂SO) using a freezing rate of 30°C min^?1. After thawing the sperm cryopreserved in glycerol lost almost all motility. The motility and survival rate of post‐thawing sperm did not show significant differences after 8 and 15 min equilibration using 15% Me₂SO as cryoprotectant; the values were significantly higher than those of 2 min equilibration. Comparisons of motility and survival rate between treatments pooled by dilution ratio showed that the effect of 1:1 ratio (sperm volume to cryoprotectant volume) was best. There was no difference between 1:3 and 1:5, and other ratioswere significantly worse.     

黄土高原3个不同降水量地点油松林地水分生产力与土壤干燥化效应模拟

应用WinEPIC模型模拟1957—2001年期间黄土高原半湿润区洛川、半干旱区延安和半干旱偏旱区榆林油松林地水分生产力演变规律和深层土壤干燥化效应。模拟结果表明:洛川、延安和榆林油松林地逐年生物量模拟值在9～17年生达到最大值(平均值分别为4.29,3.62和2.73t.hm-2),之后随降水量年际波动呈现出明显的波动性降低趋势;1～22年生期间油松林地平均年耗水量高于同期年降水量,导致林地0～10m土层土壤强烈干燥化,逐月土壤有效含水量波动性降低,洛川14～20年生、延安9～20年生和榆林6～19年生期间是油松林地土壤强烈干燥化阶段,年均土壤干燥化速度分别为176,111和69mm,此后油松林地土壤有效含水量在0～150mm范围内的较低水平上随降水量变化而波动;洛川、延安和榆林油松林地0～10m土层土壤湿度剖面分布变化剧烈,土壤湿度逐年降低,土壤干层逐年加厚,分别从15,10,6年生开始土壤干层厚度超过3m,在19年生时均已超过10m,20年生以后2～10m土层土壤湿度保持相对稳定的干燥化状态;洛川、延安和榆林油松林地水分生产力和土壤干燥化效应区域差异显著,林地土壤水分可持续利用年限约30年。     

浅谈工程项目成本的控制措施

本文简述了企业成本控制的基本原则,从项目成本控制体系的建立和施工阶段的项目成本控制两方面总结了企业成本控制的主要措施。     

2001-2005年《西南农业大学学报(自然科学版)》载文与引文分析

为了评价《西南农业大学学报（自然科学版）》的学术水平和载文质量,选取《西南农业大学学报》2001—2005年刊发的933篇论文为统计样本,对其载文量、引文及作者情况进行了统计分析。结果表明,5a间共发文933篇,其中,基金论文为787篇,基金率为84．35％;5a发文的引文总量是8356条,篇均引文8．96条;引文语种外文占总引文量的24.25％;引文类型是期刊学术论文,占72．01％。由此提出学报应改进的方面。     

离心泵压水室内部定常和非定常流动PIV测量

为研究离心泵压水室内的流动特性,利用PIV技术在内同步和外同步模式下分别测量了其内部的定常和非定常流场,详细分析了压水室内部流动现象和流动规律。结果表明,压水室内速度沿轴向分布均匀,随圆周角增大而减小;在叶轮和压水室的交界处,存在清晰的速度分界线;受蜗舌的分流作用,部分流体回流入叶轮流道,扩散管入口处速度显著降低;压水室内部周期性非定常流动规律明显,第VIII断面上,速度的大小和波动幅度沿径向均呈减小趋势,周向速度的波动与叶轮流道内部高速流区的位置有关,而径向速度的波动主要受叶片干扰和哥氏力的影响。研究结果为压水室设计以及离心泵内部流动的试验研究提供了借鉴。     

Nursery‐Box Total Fertilization Technology (NBTF) Application for Increasing Nitrogen Use Efficiency in Chinese Irrigated Riceland: N–Soil Interactions

High N fertilizer and flooding irrigation applied to rice in anthropogenic‐alluvial soil often result in N leaching and low use efficiency of applied fertilizer N from the rice field in Ningxia irrigation region in the upper reaches of the Yellow River. Sound N management practices need to be established to improve N use efficiency while sustaining high grain yield levels and minimize fertilizer N loss to the environment. We investigated the effects of Nursery Box Total Fertilization technology (NBTF) on N leaching at different rice growing stages, N use efficiency and rice yield in 2010 and 2011. The four fertilizer N treatments were 300 kg N ha⁻¹ (CU, Conventional treatment of urea at 300 kg N ha⁻¹), 120 kg N ha⁻¹ (NBTF120, NBTF treatment of controlled‐release N fertilizer at 120 kg N ha⁻¹), 80 kgN ha⁻¹ (NBTF80, NBTF treatment of controlled‐release N fertilizer at 80 kg N ha⁻¹) and no N fertilizer application treatment (CK). The results showed that the NBTF120 treatment increased N use efficiency, maintained crop yields and substantially reduced N losses to the environment. Under the CU treatment, the rice yield was 9634 and 7098 kg ha⁻¹, the N use efficiency was 31·6% and 34·8% and the leaching losses of TN were 44·51 and 39·89 kg ha⁻¹; NH₄⁺‐N was 5·26 and 5·49 kg ha⁻¹, and NO₃⁻‐N was 27·94 and 26·22 kg ha⁻¹ during the rice whole growing period in 2010 and 2011, respectively. Compared with CU, NBTF120 significantly increased the N use efficiency and decreased the N losses from the paddy field. Under NBTF120, the N use efficiency was 56·3% and 51·4%, which was 24·7% and 16·6% higher than that of CU, and the conventional fertilizer application rate could be reduced by 60% without lowering the rice yield while decreasing the leaching losses of TN by 16·27 and 14·36 kg ha⁻¹, NH₄⁺‐N by 0·90 and 1·84 kg ha⁻¹, NO₃⁻‐N by 110·6 and 10·14 kg ha⁻¹ in 2010 and 2011, respectively. Our results indicate that the CU treatment resulted in relatively high N leaching losses, and that alternative practice of NBTF which synchronized fertilizer application with crop demand substantially reduced these losses. We therefore suggest the NBTF120 be a fertilizer application alternative which leads to high food production but low environmental impact. Copyright © 2014 John Wiley & Sons, Ltd.     

耕作方式对豫南雨养区土壤微环境及冬小麦产量的影响

针对豫南雨养农业区降水基本满足作物生长需求但年内和年际间分配不均、土壤耕性差的生态实际,为解决小麦播种期和冬春干旱以及改善耕层水、肥、气、热等因子提供理论依据。于2007—2015年,在豫南雨养农业区进行了连续9a的大田定位试验,研究了不同耕作模式对小麦生长季土壤水分、容重、温度及冬小麦产量的影响。试验共设置6个处理:T1(传统翻耕)、T2(不覆盖/不深松+覆盖/免耕)、T3(覆盖/不深松+不覆盖/免耕)、T4(不覆盖/深松+不覆盖/免耕)、T5(覆盖/深松+覆盖/免耕)以及T6(不覆盖/不深松+还田/旋耕)。结果表明,(覆盖/深松+覆盖/免耕)T5可以有效提高小麦播种期0~40cm土层的含水量,为麦播提供较好的水分基础,不同耕作方式处理对冬小麦越冬期和返青期土壤日平均温度影响较小,不足以对冬小麦发育进程产生影响。(覆盖/深松+覆盖/免耕)T5能够有效降低耕层0~20cm和0~40cm的土壤容重。覆盖/深松+覆盖/免耕处理的前3a,冬小麦产量较对照有所降低,从第4年开始较对照增产,2011—2015年增产幅度分别为2.02%、2.83%、10.93%、5.88%、1.97%。以上结果表明,通过T5(覆盖/深松+覆盖/免耕)的简耕覆盖技术可以有效利用降水资源、培肥地力,提高产量,具有节本增效的作用。     

稻作区保护性耕作和小麦种植对土壤养分的影响

该文采用4个处理：常规犁耕-休闲(DTF)、常规犁耕-小麦(DTW)、保护耕作-休闲(CTF)和保护耕作-小麦(CTW),分析了10年后稻作区保护性耕作和小麦种植对土壤养分的影响。结果表明：在CTW处理下,土壤全N分别较DTF、DTW和CTF处理高10.03%、26.81%和23.17%。土壤碱解N也呈现相同的趋势;土壤全P,CTW处理下较DTF、DTW和CTF处理分别高12.93%、15.86%和21.36%。在0～10 cm土深,CTW处理下土壤有效P分别是DTF和DTW处理下的4.5和2.1倍;土壤全K在4种处理中与全N和P有类似的趋势;与处理DTF相比,Ca₂-P、Ca₈-P、Al-P、Fe-P、O-P和Ca₁₀-P在CTW下的含量迅速增加;代换态、易还原结合态、碳酸盐结合态、有机质结合态和无定形态Fe、Mn和Cu在CTW处理下含量降低,而残渣态Fe、Mn和Cu则增加。代换态和易还原锰结合态Zn在CTW处理下的含量增加,而相应地,无定形态和有机质结合态Zn则显著降低。而且,在有效Fe、Cu和Mn降低的同时,有效的Zn增加;稻作区,保护性耕作和小麦种植不仅增加表土层土壤养分的含量,而且可通过影响P、Fe、Mn、Zn和Cu的形态,缓解Fe和Mn对作物的毒害。     

柠檬酸盐对黑云母表面溶解及微结构变化的影响

采用离位培养法,结合原子力显微镜的接触成像和相位成像模式研究层状硅酸盐含钾矿物黑云母在根际环境条件下的表面溶解现象和矿物微结构转化过程。结果表明,在p H 4.0的弱酸水溶液中反应24 h时,黑云母(001)面上有微型蚀坑出现,其深度介于0.1~0.9 nm之间,表面变得比较粗糙;反应96 h时,黑云母(001)面上蚀坑较为明显,但仅占总表面的4.8%,蚀坑的深度平均为0.957 nm;反应140 h时,黑云母(001)面上有不稳定的覆盖物沉积,阻碍表层溶解过程的持续进行。在p H 4.0的柠檬酸溶液中,经过24 h培养,(001)面上有大量的蚀坑出现,单层溶解现象明显;48 h时,表面台阶溶解速率显著提高,溶解面积可达总表面的48.7%;140 h时,(001)面上有圆形状胀裂发生,表层(高度,1~2 nm)发生破裂、产生较多的黑云母碎片,溶解速率进一步提高。随着柠檬酸溶液中Na+浓度的增加,表层溶解速率增强,(001)面上也有次生覆盖物沉积。同时,界面上Na+-K+交换作用加剧,表层结构(高度,2~10 nm)胀裂现象更加明显。随着反应时间的延长,140 h时,黑云母(001)面的深层结构(深度,~20 nm)亦逐渐隆起并引起周边区域产生裂缝(深度,0.1~1.9 nm),最终导致表层微结构区域水化,形成水化云母(伊利石)。