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1.
应用高分子聚合物防治水土流失,近年来已作为水土保持化学措施。为了研究其防治效果,分别在室内、室外及土堤上做了抗风蚀和水蚀试验。其结果表明,盐碱化土堤施用聚丙烯酰胺,其防治坡面水土流失的效果是有限的,有效期为1-2 a,而且只有配合植物措施才能体现其保苗和防蚀作用。单独使用其长效性是有待研究的问题。  相似文献   

2.
通过有关文献资料调研,综述纳米黑碳在钝化修复污染土壤中的应用,分析其应用于钝化修复重金属污染土壤时尚待弄清的几个问题。结果表明:(1)由于纳米黑碳是疏水的非极性吸附剂,选择纳米黑碳作为土壤重金属钝化修复剂时,需对其进行氧化改性,以进一步提高其钝化能力。目前常用的氧化剂为氧化性无机酸、酸性高锰酸钾、双氧水、臭氧等,强烈的氧化过程,会破坏纳米黑碳微孔结构,一定程度上降低其吸附量。(2)为了明确其应用的可能性和适用范围,需揭示改性纳米黑碳对土壤中重金属的钝化机理及其影响因素。土壤CEC、pH、重金属离子的性质等可能是影响改性纳米黑碳对土壤中重金属吸附性能的主要因素。(3)充分利用改性纳米黑碳在土壤修复中的有益作用的同时,还需考虑其可能存在的生态环境负面效应,研究其在土壤中的径流迁移、渗漏等,明确其污染地表水和地下水的可能性,研究其生物效应和将吸附钝化后的纳米黑碳从土壤中移除的可能性,明确其潜在的生态环境风险。  相似文献   

3.
可持续发展战略的提出,为农业种植业提出了明确的方向。绿色农业种植符合节能环保及农业可持续发展的基本要求,在新的时代背景下,分析其技术要点并加强其推广工作也显得更加重要。因此,以绿色农业种植技术为内容,对其内涵、特点进行论述,并在此基础上对其重要性及推广要点进行具体分析。  相似文献   

4.
[目的]评价青海省高家湾滑坡稳定性,为其灾害防治提供一定指导。[方法]在对高家湾滑坡基本特征分析基础上,先开展其形成条件研究;其次,利用传递系数法和瑞典圆弧法实现其稳定性现状评价,并进一步采用长短时记忆神经网络构建其变形预测模型,实现其稳定性预测评价。结合稳定现状评价结果,实现其稳定性的综合研究。[结果]高家湾滑坡具有滑坡形成的基本条件,且具有复合多期巨型规模特征,对其防治应具有综合性;同时,滑坡现状处于稳定状态,但局部次级滑坡存在失稳可能,且在不利工况条件下,稳定性将会进一步减弱;另外,据变形预测研究结果,得出其平均相对误差均小于2%,进而验证了本文优化LSTM模型的有效性,且通过外推预测,得出高家湾滑坡变形仍将继续增加,且无收敛迹象。[结论]高家湾滑坡稳定性还会进一步减弱,趋于不利方向发展,应尽快采取必要措施切实保证滑坡稳定。  相似文献   

5.
红椎是一种具有较高使用价值的用材树种,且其自身含有的高热量也使其成为一种实用性强的薪炭材树种。红椎虽产自广西,但其对生长环境的适应能力十分强,生命力旺盛,因此具有较高的推广价值。基于此,分析红椎的生长特点、分布情况等详细信息,探讨其速生丰产栽培技术,以期为推进红椎的推广种植提供相关借鉴与参考。  相似文献   

6.
猕猴桃又叫奇异果,其形状多为椭圆,呈现褐绿色,皮表面有富含浓密的绒毛,去皮食用,内部由绿色果肉和黑色的种子组成,是一种营养丰富、口感鲜美的水果。在猕猴桃的繁殖中,十分容易产生变异,导致其优良的基因发生改变,因此,对其食用试管苗的培育方法能够确保其优良的基因不发生改变,繁殖速度也能够随之加快。  相似文献   

7.
某滑坡炭质软岩抗剪强度受含水量影响分析   总被引:2,自引:0,他引:2  
通过对某滑坡其炭质软岩在不同含水量下进行大量的抗剪强度试验,得出抗剪强度与含水量的关系曲线,分析曲线变化特征。因物质成分决定其力学性质,故进一步对岩样进行X-射线分析,得到其矿物成分;同时进行红外吸收谱分析,得到其化学成份。从而从内因上解释曲线变化特征及阐述抗剪强度受含水量的影响。  相似文献   

8.
低温对诱导小麦未成熟胚愈伤组织出愈率的影响研究   总被引:1,自引:0,他引:1  
试验研究低温处理对诱导小麦未成熟胚愈伤组织出愈率结果表明 ,6h短时间低温处理可显著提高其出愈率 ,比对照增加 1 4 3倍。随处理时间的延长其出愈率逐渐降低 ,18h后其出愈率又渐增 ,低温处理 30h时其出愈率显著高于对照 ,为对照的 1 4 1倍。  相似文献   

9.
西瓜的有限元模型及其应用   总被引:5,自引:2,他引:3  
西瓜的硬度可以通过检测其固有频率得到。试验时,采用一个摆动的木球激励被测西瓜,产生的信号由加速度传感器采集,利用ANSYS 7.0建立了西瓜的有限元模型,并确定最佳激励点及适于测量其固有频率的传感器。试验结果表明,西瓜的杨氏模量与其固有频率之间具有较高的相关性,相关系数高达0.90,西瓜的硬度可以由其杨氏模量来表征,研究结果为进一步研究西瓜硬度无损检测装置打下了基础。  相似文献   

10.
天然生物酶是一类极为重要的生物催化剂,但由于其自身的缺陷,导致其催化作用极其不稳定,限制了其在农产品检测中的应用。而制备过程简单、成本低、稳定性高的纳米酶,在农产品检测领域中具有良好的应用前景,逐渐成为了天然生物酶替代品。本文系统地介绍了纳米酶的种类,着重阐述纳米酶催化机理,总结了其在农产品领域中的应用进展,并展望了纳米酶的未来发展方向。  相似文献   

11.
In this paper, the concepts of a weakly relative hereditary module, a weakly relative coheredjtary module and a relative hereditary module are introduced . The endomorphism rings of self-hereditary modules are studied. We prove that for P a left self-hereditary modules S=EndR(P) is left semi-hereditary as a ring.  相似文献   

12.
In this study, the norms for Vitis Vinifera have been derived and compared using the Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) diagnose methods to determine the nutrient deficiency in Vineyards at Central Alborz region, Iran. A total of 200 leaf samples were collected during two years from Vitis Vinifera trees and nutrient concentrations of Mn, Zn, Fe, Mg, Ca, K, P, N, B, and Cu were measured. The results showed that there are differences between DOP and CND diagnosis methods. According to mean DOP indices for nutrient elements, the priority of the deficiency of elements was as follows: Mn > P > Ca > Fe > Cu. In addition, the CND standard norms were determined as Fci(VN) = 32.34, Fci(VP) = 34.49, Fci(VK) = 48.58, Fci(VCa) = 54.39, Fci(VMg) = 64.11, Fci(VMn) = 19.71, Fci(VZn) = 47.64, Fci(VFe) = 53.32, Fci(VCu) = 32.44, Fci(VB) = 41.59, and Fci(Rd) = 39.19 ton.ha?1. The results also showed that there is the deficiency of manganese, nitrogen, iron, and phosphorus in vineyards. Therefore, the field observations due to the implications of apparent deficiencies of nutrient elements in the gardens of the region are more consistent with the DOP method.  相似文献   

13.
An experiment was conducted with cucumber (Cueumis sativus L., cv. Sumter) plants in the vegetative phase of growth to determine effects of manganese deficiency (0.2 μM Mn) and toxicity (182 μM Mn) on fluxes of several mineral nutrients, water, and carbohydrate in the root and shoot, beginning 43 d after germination. Plants were sampled every three days from 34 to 58 d after germination. First and second derivatives of regression equations were used to estimate fluxes and study source/sink phenomena of dry weight (DW), fresh weight (FW), H2O, Cu, Fe, Mn, Zn, N, P, and K in root and shoot tissues.

With Mn sufficiency (1.8 μM Mn), both root and shoot acted as sinks for of each of the 10 dependent variables through 58 d. In contrast, Mn deficiency caused net loss of K and N from the root beginning at 53 and 56 d, respectively, and net loss of P and Fe from the shoot beginning at 57 and 58 d, respectively. With Mn toxicity, net loss of Cu, N, and K from the root began at 46, 46, and 51 d, respectively, and net loss of Fe from the shoot began at 55 d. Both Mn deficiency and toxicity increased the shoot:root ratio (S:R) of K and decreased the S:R of Fe, compared to Mn‐sufficiency. Manganese deficiency decreased the S:R of DW and H2O, and Mn toxicity increased the S:R of FW, DW, H20, and N. Under the conditions of this experiment, acute Mn toxicity affected fluxes more severely than did Mn deficiency.  相似文献   

14.
Abstract

The rates of applied phosphorus required for 90% maximum yield of Desmodiim intortum cv. Greenleaf were calculated from pot experiments using 24 fertilized and unfertilized soils from the Atherton Tableland, Queensland, Australia.

Phosphorus required was highly correlated (r2 = 0.94) with the phosphorus sorbed (P sorbed) by the soils at a supernatant solution P concentration of 0.08 ppm. P sorbed was found to be a function of phosphorus buffer capacity at 0.08 ppm ("PBC") and phosphorus extractable by acid (0.005 M H2S04) or bicarbonate (0.5 M NaHCO3). PBC was highly correlated (r2 = O.84) with a phosphorus sorption index ("PSI") derived from one addition of 500 μg P g‐1 soil.

Combining PSI with acid or bicarbonate extractable P in a multiple regression equation allowed the estimation of phosphorus required with multiple correlation coefficients of R2 = 0.80 and R2 = 0.83 respectively.  相似文献   

15.
水分利用效率(WUE)常被嵌入到多种生态系统模型中,用于评估生态系统对气候变化的响应。然而,自然条件下多种因素不仅直接影响WUE,还通过影响冠层结构等间接影响WUE,其中的影响机制仍不明晰。为了明确多种因素对冬小麦WUE的协同影响,本研究基于2015年(温暖湿润年)和2016年(温暖干旱年)涡度相关系统观测的小麦关键生育期(返青、拔节、抽穗、灌浆)的数据,分析了WUE的变化,并借助结构方程模型(SEM),以叶面积指数(LAI)为中间变量,分析了多种因素[净辐射(R_n)、空气温度(T_a)、饱和水汽压差(VPD)、风速(WS)、土壤含水量(SWC)]对WUE的影响机制。结果表明,2015年平均WUE为1.52g(C)·kg~(-1)(H_2O),2016年平均WUE为1.22g(C)·kg~(-1)(H_2O)。不管在温暖湿润年还是温暖干旱年, T_a、LAI和VPD均是影响WUE的主要因素。WUE随LAI增加而增加, Ta增加也有助于提高WUE,而当温度相近时, VPD增加会降低WUE。T_a、LAI和VPD对WUE的影响在温暖湿润年和温暖干旱年重要性程度不同,温暖湿润年最重要的影响因素为LAI,温暖干旱年为T_a; VPD在温暖湿润年既直接影响WUE,同时又通过影响LAI的变化间接作用于WUE,但在温暖干旱年仅具有直接影响。R_n在温暖干旱年和温暖湿润年表现也不相同:在温暖湿润年对WUE具有显著的影响,在温暖干旱年影响不显著,这与温暖湿润年降雨量大及降雨频次高有关。显然,模拟WUE时考虑不同年份气象条件会使结果更为准确。WS未对WUE产生显著的影响,潜在原因可能是其对冠层上部接收辐射充足的叶片影响较大,而对冠层内部叶片无显著影响。农田生态系统不同生育阶段对辐射、温度等的耐受性及响应方式不同,SEM可以将LAI设置为中间变量以综合这种阶段性的变化,因此,对于冠层结构季节变幅大的生态系统, SEM是研究其环境控制机制的有力工具。这些研究结果可为今后精确模拟生态系统WUE以及预测WUE对气候变化的响应提供科学依据。  相似文献   

16.
This study evaluated the suitability of the Mehlic h3 universal extractant as a part of a multielement test to assess the nutrient status of Australian sugarcane soils. Soil samples from BSES Soil Exchange Programs, representing all major soil types and geographic sugarcane-growing regions, were analyzed using existing BSES, acid-based extraction methods for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and phosphorus (P) and the ASPAC 10B3 method for sulfur (S). These were compared with the Mehlich 3 procedure. Mehlich 3 results for Ca, Mg, Na, S, and Mn correlated highly with the BSES procedures (R2 = 0.95, 0.98, 0.99, 0.91, and 0.91, respectively). Satisfactory correlations were also obtained with 0.1 M HCl–extracted Zn, Cu, and Fe (R2 = 0.89, 0.85, and 0.85, respectively) and with the BSES sulfuric acid (H2SO4)–extracted P (R2 = 0.81). The poorest correlation (R2 = 0.79) was observed for K. In conclusion, the Mehlich 3 procedure is suitable as a diagnostic tool to assess the basic nutrient status of Australian sugarcane soils.  相似文献   

17.
Inositol phosphates are abundant organic phosphates found widely in the environment. The sorption and desorption of organic phosphate (Po) are important processes in controlling the mobility, bioavailability and fate of phosphorus (P) in soil and sediment. The desorption characteristics of myo‐inositol hexakisphosphate (IHP) and inorganic phosphate (Pi) from goethite were studied by pre‐sorption of IHP or Pi followed by desorption by KCl, H2O, and citrate. Batch experiments and in situ attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy were used to investigate the desorption of IHP/Pi. The desorption percentage of IHP/Pi by citrate was much higher than that by H2O/KCl. The desorption of P by citrate was mainly achieved through ligand exchange, and the desorption increased with decreasing pH. Desorption by H2O was slightly greater than that by 0.02 M KCl because the electrostatic repulsion between the P molecules is larger in H2O. Due to the higher affinity of IHP for goethite than that of Pi, the maximum desorption of IHP was lower than that of Pi. Desorption curves (desorption concentration in solution vs. sorption density) of IHP or Pi on goethite by KCl or H2O was well fitted by an exponential equation, while those by citrate were well fitted by a linear equation. The desorption amounts of P in the first cycle account for more than 58% of the total desorption followed by substantial decreases in the second and third cycles. There was a re‐sorption of Pi from solution in the late stage of desorption by KCl and H2O, resulting in a sharp decrease in desorption. Re‐sorption of IHP did not occur, which is probably due to its poor diffusion into goethite. The initial desorption rate of Pi with KCl and H2O decreased with increasing pre‐sorption time, whereas that of IHP was opposite. This study indicates that strong sorption on and weak desorption of IHP from iron (hydr)oxides may explain the accumulation of IHP in soils.  相似文献   

18.
宁夏中部干旱带砂土混合覆盖下土壤蒸发估算   总被引:2,自引:0,他引:2  
为寻求一种能够有效估算宁夏中部干旱带压砂地土壤蒸发量的方法,通过微型蒸渗仪大田试验,研究了 0(S1),20%(S2),40%(S3),60%(S4),80%(S5),100%(S6)6种砂土混合比条件下土水蒸发比与表层土壤含水量的关系,并构建了压砂地土壤蒸发量估算模型.结果表明:土水蒸发比随表层土壤含水量呈分阶段变化...  相似文献   

19.
前言     
本文给出Hermite-Fejér插值的若干收敛准则.其中之一是:Hermite-Fejer插值算子对每一个连续函数一致收敛当且仅当该算子范数一致有界且该算子对两个单项式x及x2一致收敛.  相似文献   

20.
Abstract

Studies with 42 soils selected to obtain a wide range in properties showed that air‐dry and moist soils have substantial capacities for sorption of H2S from air (averages, 9.8 and 12.5 g S kg‐1 soil, respectively). Soil properties influencing the capacities of air‐dry soils for sorption of H2S included sand and clay contents, DCB‐soluble Mn, exchangeable Na, DCB‐soluble Fe, and total DCB‐soluble metals. The corresponding capacities of moist soils were influenced by sand and clay contents, DCB‐soluble Mn, and surface area. It was possible to closely predict the H2S sorption capacities of both air‐dry and moist soils (R2 = 0.804 and 0.918, respectively) from consideration of their properties.  相似文献   

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