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1.
This article,according to the author‘s working experience in a hydropower project,briefly introduces some basic knowledge about bidding process and sample contract document.It is aiming at giving a common knowledge to the students who will be involved in work relating to bid after their graduation in the college.It is hoped that this kind of knowledge can help people properly use funds for a project and thus corruption can be minimized.  相似文献   

2.
The aphid quantity ratio(AQR) is defined as the number of aphids on each cultivar divided by the number of aphids on all cultivars. AQR is based on the correlation between aphid populations and their host plants and is an important tool that has been utilized in evaluating Medicago sativa(alfalfa) cultivar resistance to aphids. However, assessment of alfalfa resistance to aphids can be confused by the presence of aphid predators, causing the assessment of plant resistance to aphids to be based on incorrect aphid population data. To refine the AQR and account for the effect of predators on aphid population assessments, we introduced a parameter ‘α', corresponding to the predator quantity ratio, and used αAQR as the ratio to quantify aphid populations. Populations of both aphids(4 species) and their predators(12 species) occurring in 28 M. sativa cultivars were sampled over two years at a research station near Cangzhou, Hebei Province, China. Results showed that the most suitable evaluation period was from May to June, as the aphid population was stable during this period. Compared with the AQR method, the predator population numbers based on the αAQR had a significant inverse relationship with aphid population numbers and the 28 cultivars were clustered into three classes: the resistant class, tolerant class, and susceptible class. In addition, 17 cultivars were reassigned when evaluated using αAQR. All numerical values calculated by αAQR were displayed as a Gaussian distribution, which showed that the 28 cultivars could be clustered into nine groups using a median value(±SE) of 1±0.1. Hence, ongoing alfalfa breeding trials will be assessed using the αAQR to establish a robust system that includes agronomic performance parameters in order to generalize the new method for further studies.  相似文献   

3.
Plastein reaction is considered a reversal of the usual protein hydrolysis by proteinase, which was applied to prepare a higher-molecular, protein-like substance. It can improve biological value and functional properties of food proteins, meliorate flavor of protein hydrolysates and, especially, provide a way to synthesize new sources of proteins. Although the mechanism(s) of the plastein reaction is not clarified, it will have great values in food industry with the development of technologies in enzymology and microbiology.  相似文献   

4.
The observations of 25-yr long-term experiment in Zhejiang paddy soils showed that the soil organic matter could increase continuously with applying organic manure, and the increase in rate enhanced along with the application rates of organic manure. By mathematical modeling, the soil organic matter increased by 22 kg when 1 t of fresh FYM was applied. The CO2 emission resulting from the mineralization of soil organic matter increased with the increase in the application rate of the organic manure as well as the increase in the root residues. It is expected that the CO2 emission will be at 10.04-21.61 t ha^-1 yr^-1 when 16.5-49.5 t ha ^-1 yr^-1 of fresh FYM is applied. The soil organic carbon from mineralization and release of applied organic carbon （fresh FYM and root residues） will affect the CO2 concentration in the atmosphere. So, the higher the application rate of organic manure, the more is the fixed organic carbon. The CO2 fixation will be at 1.885-3.463 t ha^-1 yr^-1 when 16.5-49.5 t ha^-1 yr^-1 of fresh FYM is applied. Thus, the CO2 fixation will increase by 46.7 kg by applying 1 t fresh FYM. To apply organic manure continuously in rice fields may reduce the contribution to the increase of CO2 concentration in the atmosphere.  相似文献   

5.
This paper reviewed rainwater collection and water resource management in Ningnan County in southwestern mountain of China,as a case study for solving the problems of water management in a simple and sustainable way. In this mountainous agriculture system,private agricultural enterprises were introduced into local mountain agriculture to solve capital fund shortage for the construction of rainwater harvesting system. Agreement was signed by private agriculture enterprises with the target farmers to subscribe for the household agriculture production at a protection price. Cash invested by the enterprise and subsidy from the government were collected for purchasing materials,while the farmers supplied labors for the construction of water harvesting systems. The system solved the share of input and benefits between the local government,enterprise and household farms successfully. In addition,the micro water harvesting tanks and micro irrigate systems extend quickly in this mountainous county. Up to 2007,more than 12 000 rainwater harvesting tanks had been established and more than 8.5×104 hm2 dry arable land accounting for nearly 75% of the total arable land had been irrigated efficiently. Per capita income of farmer had been increased by 14 times in the past 20 years. Considerable potential for further improvement in implementation of the models for solving water shortage and water resource management in mountain region maybe depend on more local private agriculture enterprises and households than the government.  相似文献   

6.
Intraspecific competition is a common phenomenon in agricultural production,and maize is one of the most sensitive grass species to intraspecific competition due to its low tillering ability.This study evaluated and analyzed intraspecific competition in maize,and screened competitive indices that could be used to evaluate intraspecific competition in a maize population.A 2-year field experiment was conducted using the maize hybrid Zhongdan 2 at 12 plant densities ranging from 1.5 to 18.0 plants(pl)m~(–2).The results showed that the response of single-plant grain yield and dry matter at harvest to increased plant density decreased exponentially and that the harvest index decreased linearly.The response of population-level grain yield to plant density was curvilinear,producing a maximum value at the optimum population density.However,the yielddensity equation agreed well with the Steinhart-Hart equation curves,but not with the quadratic equation curves reported by most previous studies.Competitive indices are used to evaluate competition in a plant population or plant species.The present results show that competitive intensity(CI)and absolute severity of competition(ASC)increased with increasing plant density;however,relative yield(RY)and relative reproductive efficiency(RR_(eff))decreased.The different responses of these indices reflect different aspects of competition.According to the analysis of CI,ASC,RY,and RR_(eff),higher CI and ASC values indicate higher intraspecific competition,whereas higher RY and RR_(eff) values indirectly reflect lower intraspecific competition.These competitive indices evaluate not only the intraspecific competitive intensity under different plant densities of the same cultivar but also those of different cultivars under the same plant density.However,some overlap exists in the calculations of ASC,CI,and RY,so one could simply select any one of these indices to evaluate intraspecific competition in a maize population.In conclusion,the present study provides a method to evaluate intraspecific competition in maize populations,which may be beneficial for breeding high-yield maize varieties in the future.  相似文献   

7.
Napier grass, an important forage crop with potentials in multi-purpose applications, is widely grown throughout the tropics and subtropics. Low temperature severely limits its productivity and geographical distribution in temperate regions of the world. In this study, we investigated the effect of exogenous abscisic Acid(ABA) on chilling tolerance of napier grass(Pennisetum purpureum Schum.) seedlings. Seven-day-old napier grass seedlings were cultured in dd H_2O or ABA solution at different concentrations and exposed to 1 ℃ for different time durations. The chilling injury, membrane stability index(MSI) and proline content were estimated from leaf samples. The results showed that there was obvious morphological injury of leaf blighting and restrained growth for the seedlings under chilling stress, but this damage can be largely reduced(by 2/3) when the seedlings were treated by 100 μmol/L ABA in the culture solution, and that the application of exogenous ABA can help to maintain a good stability of leaf cell membrane as expressed by a high MSI value and a low level of proline in leaf cells. These results suggested that exogenous ABA can significantly alleviate chilling injury in napier grass seedlings by maintaining the stability of leaf cell membrane during chilling stress, and that the chilling tolerance was not ensured by a proline accumulation although a passive accumulation of proline was observed in the seedlings under chilling stress. Our results lay a preliminary foundation for future investigations on the molecular mechanisms of ABA induced chilling or freezing tolerance in napier grass.  相似文献   

8.
Crop growth and yield depend on canopy light interception(LI). To identify a low-cost and relatively efficient index for measuring LI, several color attributes of red-green-blue(RGB), hue-saturation-intensity(HSI), hue-saturation-value(HSV) color models and the component values of color attributes in the RGB color model were investigated using digital images at six cotton plant population densities in 2012–2014. The results showed that the LI values followed downward quadratic curves after planting. The red(R), green(G) and blue(B) values varied greatly over the years, in accordance with Cai's research demonstrating that the RGB model is affected by outside light. Quadratic curves were fit to these color attributes at six plant population densities. Additionally, linear regressions of LI on every color attribute revealed that the hue(H) values in HSI and HSV were significantly linearly correlated with LI with a determination coefficient(R2)≥0.89 and a root mean square error(RMSE)=0.05. Thus, the H values in the HSI and HSV models could be used to measure LI, and this hypothesis was validated. The H values are new indexes for quantitatively estimating the LI of heterogeneous crop canopies, which will provide a theoretical basis for optimizing the crop canopy structure. However, further research should be conducted in other crops and under other growing and environmental conditions to verify this finding.  相似文献   

9.
Quantitative study of the impact of Shanghai World Expo on green GDP （GGDP） is significant for deploying sustainable development policy in China. The formula of GGDP is： GGDP = GDP--the loss of natural resources environment relegation cost ＋ comprehensive utilized value of waste. Based on this, the study employed vector autoregressive （VAR） model to predict the value of GGDP and other economic variables on condition that there was no Shanghai World Expo. Then Influence of Expo is defined as the rate of increase of GGDP. The result demonstrated that Shanghai World Expo had accelerated the growth rate of GGDP vastly with the elimination of effect of Beijing Olympics. Additionally, the quantitative analysis between GGDP and other economic variables suggested GGDP would replace GDP to evaluate the development of economy. Finally, the paper proposed that incidents like World Expo can enhance the level of influence for a country and that post-impact of Shanghai Expo should continue to be used to promote GGDP and that GGDP should serve as one of the indicators in assessment of political achievement.  相似文献   

10.
Pseudorabies virus(PRV), in the family Herpesviridae, is a pathogen of Aujeszky's disease, which causes great economic losses to the pig industry. Recent outbreaks of Pseudorabies imply that new control measures are urgently needed. The present study shows that kaempferol is a candidate drug for controlling PRV infection, as it possesses the ability to inhibit PRV replication in a dose-dependent manner in vitro. Kaempferol at a concentration of 52.40 μmol L–1 could decrease PRV-induced cell death by 90%. With an 50% inhibitory concentration(IC50) value of 25.57 μmol L–1, kaempferol was more effective than acyclovir(positive control) which has an IC50 value of 54.97 μmol L–1. A mode of action study indicated that kaempferol inhibited viral penetration and replication stages, decreasing viral loads by 4-and 30-fold, respectively. Addition of kaempferol within 16 h post infection(hpi) could significantly inhibit virus replication, and viral genome copies were decreased by almost 15-fold when kaempferol was added at 2 hpi. Kaempferol regulated the NF-κB and MAPKs signaling pathways involved in PRV infection and changed the levels of the target genes of the MAPKs(ATF-2 and c-Jun) and NF-κB(IL-1α, IL-1β and IL-2) signaling pathways. The findings of the current study suggest that kaempferol could be an alternative measure to control PRV infection.  相似文献   

11.
王倩兰  温丹苹 《安徽农业科学》2013,41(13):6026-6028
基于全国范围内实行购物袋有偿使用制度这一背景,建立了基本的"农产品供应商(超市)—消费者"博弈模型,讨论了纳什均衡和帕累托均衡情况下各博弈参与人的"成本"和"收益",得出纳什非合作均衡和帕累托合作均衡的条件,进而肯定了购物袋有偿使用的必要性。  相似文献   

12.
自然保护区管理与可持续发展的实现与周边社区居民的影响密不可分。通过构建动态博弈模型,对当今我国自然保护区与周边社区居民之间普遍存在的利益问题进行探讨,得出不同情况下该动态博弈的子博弈完美纳什均衡,最后对最优的子博弈完美纳什均衡的策略组合进行讨论并提出相关建议,以期实现自然保护区与周边社区居民和谐发展。  相似文献   

13.
植保技术与食品安全中政府与农户行为的博弈分析   总被引：1，自引：0，他引：1  
以多学科交叉融合的视野,建立了植保技术与食品安全中政府与农户的博弈模型,并对其进行求解与分析,在此基础上,还从实证的角度加以论证及评述。研究结果表明：政府扶持决定该博弈中不同条件下的子博弈精炼纳什均衡。  相似文献   

14.
Computer modeling of 611 high-quality analyses of normal ground waters from diverse geographic areas reveals that aqueous oxidation-reduction reactions are generally not at equilibrium. Multiple redox couples present in individual samples yield computed Nernstian Eh (redox potential) values spanning as much as 1000 millivolts. The computed Eh values do not agree with each other, nor do they agree with the single "master" value measured in the field with a platinum electrode. Because of internal disequilibrium, the use of any measured Eh value as input to equilibrium hydrogeochemical computer models will generally yield misleading results for normal ground waters.  相似文献   

15.
基于微观视角，梳理房地产财富效应的作用机理，构建了房价影响居民收入的理论基础，并利用湖南省1998~2014年数据实证检验了房价波动对居民收入的影响程度.实证结果表明，房价与居民收入之间具有长期协整关系，若房地产市场繁荣致使房价增长1%，则居民收入相应增长0.519%.通过向量误差修正模型检验发现，当短期房价波动偏离长期均衡值时，以负0.33的力度反向作用机制将波动拉回到长期均衡值.  相似文献   

16.
运用广义最大元方法在非传递性偏好下给出了博弈均衡的存在性定理，推广了一些经典的博弈均衡存在性定理.在文中介绍策略式博弈的Nash均衡具有宽泛的条件，在微观经济理论中有广泛的应用.  相似文献   

17.
针对目前敌磺钠在单季茭白上应用的不规范,研究了敌磺钠的不同使用时期、浓度和次数对单季茭白产量和产值的影响。结果表明：在单季茭白一年收二茬种植地区,敌磺钠能显著促进茭白结茭,茭白采收期提早50 d左右。在茭白移栽150,160和175 d各喷施一次浓度为0.5 g·L-1（有效成分）的敌磺钠即能促进茭白结茭,提高产量。在纯单季茭白种植地区,喷施1次敌磺钠可明显提早茭白采收期,同时提高茭白产量和产值,但随着使用次数的增多,茭白产量和产值明显下降。建议最多使用1次浓度为1 g·L-1（有效成分）的敌磺钠,在茭白移栽后40～60 d使用效果较佳。  相似文献   

18.
(1) A common error in text-books on physical chemistry is pointed out. It is hoped that the correct value for the triple point temperature, +.0098 degrees C, will be given in new books and in succeeding editions of the books surveyed above. (2) Inconsistencies in the vapor pressure values for ice and for liquid water near 0 degrees C are pointed out. (3) The equilibrium vapor pressures for ice and liquid water under two different sets of equilibrium conditions are compared with the triple point pressure.  相似文献   

19.
乌鲁木齐市耕地资源价值评价与分析   总被引：3，自引：2，他引：1  
在参考大量国内外相关文献的基础上,依据实际情况,首先对乌鲁木齐市的耕地资源价值进行了理论分析.其中包括耕地资源价值的理论基础和耕地资源价值内涵两部分,从而明确了耕地价值的构成,初步提出了耕地价值评估框架体系.接着研究了耕地资源价值的评价方法,即收益还原法、替代法和意愿调查法这三种方法的基本原理和步骤等,并在此基础上,以乌鲁木齐市为例计算出了耕地资源的经济产出价值、社会保障价值、非市场价值和总价值.研究结果表明,乌鲁木齐市耕地资源的社会保障价值和非市场价值在总价值中占有一定的比重.评价结果证明,在以往的耕地征收过程中,人们忽视了耕地资源的其他价值,因此造成耕地征收价格严重偏低,这既是对农民利益的一种剥夺,也是对耕地资源价值的一种过低补偿利用.经济产出价值以外的价值应该得到认可,并应在土地交易中得以体现.最后,对该研究作了总结,并对其中存在的一些问题进行了讨论.  相似文献   

20.
三峡库区秭归县农业生态系统退化综合评价   总被引：4，自引：0，他引：4  
建立了农业生态系统退化评价指标体系,包括单调性指数,非均衡指数,系统非稳定指数,非持续性指数,生产力阻滞指数,系统封闭性系数,土壤养分退化指数、系统钝化指数等８个指标,运用这些指标对三峡库区秭归县１６个乡镇农业生态系统进行了评价。  相似文献   

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