大学生网络成瘾的原因 危害及对策

大学生网络成瘾不仅影响学习,而且影响身心健康。学校、家庭和社会应通力协作,共同营造和谐的社会文化氛围。     

不同粗蛋白和氨基酸组合日粮对实验兔氮代谢和免疫功能的影响

选用100日龄成年日本大耳白兔36只,随机分为6组（Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ组）,分别喂以6种不同粗蛋白和氨基酸组合的日粮。其中Ⅰ-Ⅲ组日粮粗蛋白水平为12％,赖氨酸含量分别为0．72％,0．9％和1．08％,含硫氨基酸含量分别为0．52％,0．65％和0．78％：Ⅳ—Ⅵ组日粮粗蛋白水平为16％,赖氨酸与含硫氨基酸组成分别与Ⅰ-Ⅲ组相同。通过饲养试验、氮代谢试验和免疫学实验。观察这6种粗蛋白和氨基酸组合日粮对实验兔的氮代谢和免疫功能的影响。试验结果表明,动物的日增重和氮利用率以Ⅲ、Ⅳ组最高,Ⅰ、Ⅵ组最低,Ⅲ、Ⅳ组分别与Ⅰ、Ⅵ差异显著（P〈0．01）,但Ⅲ组的总氮排泄量明显低于Ⅳ组（P〈0．01）。Ⅲ、Ⅳ组动物的脾脏指数和胸腺指数也都高于其他4组动物,Ⅳ组动物的脾脏指数分别与Ⅰ、Ⅱ、Ⅴ和Ⅵ组差异显著（P〈0．01）。抗卵苛白蛋白抗体阳性的动物数以Ⅲ组最多,分别与Ⅱ、Ⅴ和Ⅵ组差异显著（P〈0．05）。血清总蛋白含量随日粮氨基酸水平提高有上升趋势,血清尿素氮含量以Ⅴ和Ⅵ组最高,与其他各组差异显著（P〈0．01,P〈0．05）。综上所述,Ⅲ、Ⅳ组日粮粗蛋白和氨基酸组合比较适宜,考虑到Ⅳ组氮排放量较高,故以Ⅲ组最佳。     

楠木优树子代苗期性状遗传变异研究

利用60株楠木优树单系种子在政和国有林场开展楠木优树子代苗期遗传变异研究,对1年生苗木苗高的调查分析表明,苗高在不同家系间存在极显著差异,这种差异主要由遗传因素决定;1年生楠木优树子代苗木平均苗高为0.39 m,变幅为0.11~0.56 m;从参试家系中初步选择出14个优良家系,其平均苗高为0.51 m,平均遗传增益为30.39%,选择效果明显。     

大学生网络成瘾的原因分析及差异化防治策略

大学生网络成瘾问题的出现是诸多因素影响的结果。目前，大学生网络成瘾的类型主要有网络游戏成瘾、网络色情成瘾、网络交际成瘾等类型。本文就大学生网络成瘾的各种类型的产生原因进行分析，并在此基础上提出相对应的差异化防治策略，以期提高解决大学生网络成瘾问题的有效性和针对性。     

Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates

Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha⁻¹), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43 kg N ha⁻¹, for the 142 kg N ha⁻¹ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60 cm depth was 46 and 138 mg l⁻¹, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.     

甜瓜株型性状的遗传分析

为了明确了甜瓜(Cucumis melo L.)主要株型性状的遗传模型与基因的作用方式,并估测了主基因遗传效应与遗传力,本研究以网纹甜瓜RE-19(Cucumis melo var.cantalupensis Naudin)和哈密瓜AM-5(Cucumis melo var.ameri Pangalo)为亲本,构建4世代群体(P1、P2、F1和F2),对甜瓜4个株型性状采用植物数量性状主基因+多基因混合遗传模型分析法进行了遗传分析。结果表明,节间长和侧枝长遗传符合E-2模型,即两对加性-显性主基因+加性-显性多基因模型,主茎直径遗传符合E-1模型,即两对加性-显性-上位性主基因+加性-显性多基因遗传模型,叶面积遗传符合C-0模型,即加性-显性-上位性多基因遗传模型。节间长、侧枝长和主茎直径的主基因遗传率分别为75.03%、54.86%和42.83%。节间长、侧枝长、主茎直径和叶面积的多基因遗传率分别为2.68%、6.41%、2.1%和55.47%。4个性状遗传变异平均值分别占其表型变异的77.68%、61.06%、50.25%和55.47%,表明甜瓜株型相关的4个性状主要受遗传因子控制,且甜瓜节间长与侧枝长主基因遗传力较高,主茎直径主基因遗传力较低,而叶面积受多基因控制,无主效基因。因此,在甜瓜株型育种中,在早期世代进行节间长与侧枝长的选择是有效的,而对主茎直径和叶面积的选择,宜在高代进行选择。本研究为甜瓜的株型改良育种提供了理论基础。     

Bulk density by Proctor test as a function of texture for agricultural soils in Maputo province of Mozambique

Soil degradation processes may be of various kinds, including soil compaction. The present study was carried out with the objective of assessing the sensitivity of agricultural or recently abandoned soils in Maputo province of Mozambique to compaction. The assessment is based on the maximum of bulk density attained using the Proctor test (MBD).

In this study the soil texture is expressed by silt plus clay (S + C) or clay (C). The relations between the soil texture and MBD, and between soil texture and critical water content (CWC—soil water at which MBD is attained) were determined. Selected soils range from 10 to 74% of S + C and 9 to 60% of C.

The results suggest there is a relationship between the considered parameters, being that between S + C and MBD or CWC, the best. For MBD the relationship is represented by two quadratic equations with the boundary in between these being a S + C value of 25% and C value of 20%.

Based on the obtained results, one can conclude that the selected parameters may be a useful basis for estimation of the sensitivity to compaction of the Maputo province's soils. It is recommended that similar studies be carried out for soils under forest land and for soil of other provinces to establish the national physical degradation hazard as a function of soil parameters determined routinely and at low cost. The suggested parameters are texture and soil organic matter (SOM).     

菜园土壤不同施肥模式下小青菜生长和品质及其生态化学计量学特征

利用盆栽试验研究了不同施肥处理对小青菜生长和品质的影响,并在此基础上利用生态化学计量学方法研究了小青菜生长和品质与其生态化学计量学特征之间的相关关系。结果表明在盆栽的条件下施氮量为180kg/hm2是小青菜生长较为合适的水平,能达到节氮保产的效果。在氮水平为180kg/hm2下,有机无机肥配施模式1(含有氨基酸肥料)提高了小青菜地上部的生长、碳浓度、光合速率、可溶性总糖、蔗糖、游离氨基酸含量和根系鲜重,且这些指标与其地上部C/N(碳氮比)和C/P(碳磷比)之间存在显著正相关关系,而与施肥模式中C/N和C/P之间存在正相关趋势,但相关关系不显著。此外,有机无机肥配施模式1降低了小青菜的地上部硝酸盐含量,且该指标与其地上部和施肥模式中N/P(氮磷比)、C/N、C/P和P/K(磷钾比)之间均不存在相关关系。因此,有机无机肥配施模式1促进了小青菜地上部和根系生长,提高了光合速率,改善了小青菜地上部的品质,是一种科学的施肥措施。     

农业物联网技术应用及创新发展策略

农业是物联网技术应用的重点领域之一,也是物联网技术应用需求最迫切、难度最大、集成性特征最明显的领域。该文对农业物联网国内外技术应用现状、存在的问题以及农业领域关键应用环节进行了深入分析,在此基础上提出了农业物联网未来技术发展重点以及对策措施。农业物联网未来技术发展重点:农业物联网信息感知与识别技术,农业物联网自组织网络部署与信息传输技术,农业物联网自组织网络部署与信息传输技术,农业物联网安全监管与服务质量保障技术。农业物联网对策措施:加强农业物联网技术规范研究,加强核心关键技术产品研发,加强农业物联网技术集成平台建设,加强农业物联网产品设备检测,加强农业物联网应用布局,进一步优化和完善政策环境。该研究为中国农业物联网可持续发展提供决策参考。     

Two-dimensional Optimum Cutting Stock Method Based on Internet and Its Implementing Technique

Two dimensional Optimum Cutting Stock is a NP complicated problem. Each of optimum software gets the cutting results by using proximate and heuristic methods. But different optimum methods and their optimum software may not realize perfect effect according to certain data framework. Furthermore, enterprises can not buy lots of optimum software to choose the most optimized plan. Because of such problems, this paper provides a two dimensional optimum cutting stock method based on Internet and offers the real implementing technique of such method. The experiments, show that this method promotes the general optimum effect of two dimensional optimum cutting stock greatly.