首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 281 毫秒
1.
Chlorination is usually an economical method for treating clogging in drip emitters during sewage application. Appropriate assessment of the responses of soil and crop is essential for determining an optimal chlorination scheme. During 2008 to 2009, field experiments were conducted in a solar-heated greenhouse for tomato drip irrigated with secondary sewage effluent, to investigate the influences of chlorine injection intervals and levels on soil chemical properties and nitrogen uptake. Injection intervals ranging from two to eight weeks and injection concentrations ranging from 2 to 50 mg L-1 were used. A salinity factor and a nutrient factor were extracted from the pool of the nine soil chemical constituents using factor analysis method. The results demonstrated that chlorination practices increased the residual Cl in the soil, resulting in an increased salinity factor, especially for the frequent chlorination at a high injection concentration. Chlorination weakened the accumulation of nutrients factor in the upper soil layer. Nitrogen uptake of the tomato plants also was inhibited by the increased salinity in the upper soil layer caused by high chlorination levels. In order to reduce the unfavorable effect on soil chemical properties and nitrogen uptake, chlorination scheme with concentrations of lower than 20 mg L-1 was recommended.  相似文献   

2.
Application of fertilizer has been found to significantly affect soil N cycling. However, a comprehensive understanding of the effects of long-term fertilization on soil gross N transformation rates is still lacking. We compiled data of observations from 10 long-term fertilization experiments and conducted a meta-analysis of the effects of long-term fertilization on soil gross N transformation rates. The results showed that if chemical fertilizers of N, P and K were applied in balance, soil p H decreased very slightly. There was a significantly positive effect of long-term fertilization, either chemical or organic fertilizers or their combinations, on gross N mineralization rate compared to the control treatment(the mean effect size ranged from 1.21 to 1.25 at 95% confidence intervals(CI) with a mean of 1.23), mainly due to the increasing soil total N content. The long-term application of organic fertilizer alone and combining organic and chemical fertilizer could increase the mineralization-immobilization turnover, thus enhance available N for plant while reduce N losses potential compared to the control treatment. However, long-term chemical fertilizer application did not significantly affect the gross NH4+ immobilization rate, but accelerated gross nitrification rate(1.19; 95% CI: 1.08 to 1.31). Thus, long-term chemical fertilizer alone would probably induce higher N losses potential through NO3– leaching and runoff than organic fertilizer application compared to the control treatment. Therefore, in the view of the effects of long-term fertilization on gross N transformation rates, it also supports that organic fertilizer alone or combination of organic and chemical fertilizer could not only improve crop yield, but also increase soil fertility and reduce the N losses potential.  相似文献   

3.
To evaluate the effects of duck hepatitis virus-1 （DHV-1） on the body weight gain in duck and the effects of silymarin on it in vivo, 100 10-d-old ducks, both male and female, were collected to be subjected to the test. The experiments were conducted in 8 groups： in group 1-3, the animals were inoculated with 1：105 diluted duck hepatitis virus （DHV-1） infected allantoic fluid and given 0, 30, and 50 mg kg^-1 BW d^-1 silymarin orally, respectively. In group 4-6, the animals were inoculated with 1：5 × 105 diluted DHV-1 infected allantoic fluid and given 0, 10, and 30 mg kg^-1 BW d^-1 silymarin orally, respectively. In group 7, the animals were given 10 mg kg^-1 BW d^-1 silymafin only. Group 8 was the control one treated by injecting sterillized saline into the leg muscles. All the silymarin was given from 0 to 4 d after inoculation of the virus. By the 5th d after inoculation, the vein blood was drawn from the dorsal foot vein and the plasma samples were collected and stored at -20℃. The body weight gain （BWG） was measured from 0 to 10 d after inoculation. The plasma IGF-I, T3, and T4 concentrations were measured by radioimmunoassay （RIA）. At the virus dose of 1：5 ×105 diluted virus infected allantoic fluid, the inoculation of the virus enhanced the BWG significantly compared with that of the control （P〈 0.01）, while 10-50 mg kg^-1 BW d^-1 silymarin could counteract the effects of the virus on the BWG dose-dependently. The plasma IGF-I levels showed no correlation with the BWG, but the T3 levels showed a same tropism with the body weight gain. The present results indicated that sublethal DHV-1 enhanced the body weight gain of ducklings significantly, and the silymarin could counteract this effect in vivo.  相似文献   

4.
The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.  相似文献   

5.
Long-term straw return is an important carbon source for improving soil organic carbon(SOC) stocks in croplands, and straw removal through burning is also a common practice in open fields in South China. However, the specific effects of long-term rice straw management on SOC fractions, the related enzyme activities and their relationships, and whether these effects differ between crop growing seasons remain unknown. Three treatments with equal nitrogen, phosphorus, and potassium nutrient inputs, including straw/ash and chemical nutrients, were established to compare the effects of straw removal(CK), straw return(SR), and straw burned return(SBR). Compared to CK, long-term SR tended to improve the yield of early season rice(P=0.057), and significantly increased total organic carbon(TOC) and microbial biomass carbon(MBC) in double-cropped rice paddies. While SBR had no effect on TOC, it decreased light fraction organic carbon(LFOC) in early rice and easily oxidizable organic carbon(EOC) in late rice, significantly increased dissolved organic carbon(DOC), and significantly decreased soil p H. These results showed that MBC was the most sensitive indicator for assessing changes of SOC in the double-cropped rice system due to long-term straw return. In addition, the different effects on SOC fraction sizes between SR and SBR were attributed to the divergent trends in most of the soil enzyme activities in the early and late rice that mainly altered DOC, while DOC was positively affected by β-xylosidase in both early and late rice. We concluded that straw return was superior to straw burned return for improving SOC fractions, but the negative effects on soil enzyme activities in late rice require further research.  相似文献   

6.
Plant growth and crop production depend to a large extent on soil N supplying capacity （SNSC）： The higher the SNSC, the higher the dependence of crops on soil and the lower the N fertilizer recovery. Of the SNSC, soil organic N （ON） played a key role in supplying N nutrient to crop production and still does in many subsistence and low-input farming systems. In this paper, soil ON contents, types, chemical components and its contribution to plant production are reviewed up to date in details, the characteristics of ON in dryland soils discussed together with its chemical components, and the mineralization and availability to plants of some important chemical components are emphasized at the last part for practical considerations.  相似文献   

7.
As the society is developing,people communicate more and more fiequently,therefore,the massages interpreted by body language become more and more important in human communication.What‘s more,body language becomes increasingly crucial in teaching and learning.Thus,it is necessary to study body language in order to develop human communication skills.  相似文献   

8.
To investigate the dynamic change of heat shock protein 90 （Hsp90） in the genesis and development of tumor, we successfully established tumor animal model using Marek’s disease and then determined the location of Hsp90 in the tumor tissue using immunohistochemistry method, the antibody titer level of Hsp90 in the serum and the expression level in the tissue using enzyme-linked immunosorbent assay （ELISA） method. Our result showed that Hsp90 location in the tumor tissue was signiifcantly associated with the tumor cell and most in the cytoplasm of the tumor cell, and Hsp90 expression level in the tissue and the antibody titer level in the serum was most signiifcantly increased with the development of tumor. This is the ifrst report to show the presence of Hsp90 in tumor tissues induced by the Marek’s disease, with its expression correlated to the tumoral grading. These data may also be valuable for developing new molecular anti-cancer therapies.  相似文献   

9.
The paper compared the effects of application of farm manure with chemical fertilizers on nitrification and denitrification in black soil, the result showed that the numbers of nitrobacterias and denitrobacterias in farm manure treatment were both higher than that of other treatments. The intensity of denitrification in chemical treatment was higher than that of manure treatment. The content of organic matter in soil was correlated with the intensity of nitrification and denitrification, and the coefficients were resnectively 0.9981 and 0.8693.  相似文献   

10.
Improved utilization of rice(Oryza sativa L.) straw and Chinese milk vetch(Astragalus sinicus L., vetch) has positive effects on rice production. So far, few studies have investigated the productivity of vetch under different residue management practices in double-rice cropping system. The effects of rice straw on the growth and nutrient accumulation of vetch across seven years(2011–2017) and the subsequent effects of rice straw and vetch on two succeeding rice crops in a vetch–rice–rice cropping system, with the vetch established by relay cropping, were examined. The seven-year double-rice experiment consisted of the following treatments:(1) 100% chemical fertilizer(F-F100);(2) only vetch without chemical fertilizer(M-Con);(3) 80% chemical fertilizer plus vetch plus a low-cutting height(low-retained stubble) with the removal of straw(M-F80);(4) 80% chemical fertilizer plus vetch plus a low-cutting height with the retention of straw(M-F80-LR);(5) 80% chemical fertilizer plus vetch plus a high-cutting height(high-retained stubble) with the retention of straw(M-F80-HR); and(6) no fertilizer(F-Con). The yields of the two rice crops after vetch were not affected by either the cutting height of stubble with retention of straw or by the management of straw(retention vs. removal) with low-cutting height of stubble. The yields of the two rice crops after vetch were significantly higher for M-F80-HR than for M-F80-LR, but the relative contributions of the high-cutting height and straw retention to the higher rice yield could not be determined in this study. The yield stability of the double-rice grain in M-F80-HR was also increased, as determined by a sustainable yield index. Significant increases in vetch biomass and nutrient uptake were observed in the fertilized treatments during the rice season compared with the unfertilized treatments. In M-F80-HR plots, improvements in the growing environment of the vetch by conserving soil water content were associated with the highest vetch biomass, nutrient uptake, and yield stability of vetch biomass. These increased nutrient inputs partially replaced the demand for chemical fertilizer and stimulated the rice yields. It can be concluded that retaining higher-cutting stubble residues with straw retention could be the best straw management practice for increasing the vetch biomass and nutrient use efficiency, thereby allowing utilization of high-cutting height with retention of straw and vetch to improve the stability of rice productivity in a double-rice cropping system.  相似文献   

11.
为寻找医治艾氏腹水癌的新型制剂,并评价药效,对小鼠腹腔注射肿瘤细胞,建立荷艾氏腹水癌细胞(EAC)的小鼠模型;并于接种后第7天开始用抗癌药,观察荷瘤小鼠(接种EAC后产生血性腹水的小鼠)的生存周期,通过对动物体内抗氧化水平指标(SOD、GSH、MDA)的检测,判定硒化合物的保护作用;用流式细胞术及对细胞进行DNA梯检测,评估药物对肿瘤细胞调亡的影响。结果表明含硒化合物,尤其是有机硒化合物,甲基硒代半胱氨酸(SeMC)与抗癌药长春新碱联合应用可使荷瘤小鼠的生存期延长、机体的抗氧化水平升高及肿瘤细胞凋亡率增多,较对照组有显著差异(P<0.01)。研究认为,含硒化合物与医用长春新碱联用对荷瘤小鼠的保护性,主要是出于硒的抗氧化能力,以及使长春新碱促进肿瘤细胞的凋亡来实现的。  相似文献   

12.
牛蒡子醇提物抑制小鼠宫颈癌U14生长的研究   总被引：1，自引：0，他引：1  
通过建立小鼠宫颈癌U14实体瘤与腹水瘤2种动物模型,观察牛蒡子醇提物对实体瘤抑瘤率和腹水瘤生命延长率的影响。结果发现,以阴性对照组为基础,牛蒡子醇提物3个剂量组及环磷酰胺(CTX)阳性对照组实体瘤各组抑瘤率分别为31.7%、49.7%、57.4%和83.6%(P<0.01);腹水瘤各组生命延长率分别为39.8%、46.6%、62.5%和91.6%(P<0.01)。表明牛蒡子醇提物对小鼠宫颈癌U14的生长有一定的抑制作用。  相似文献   

13.
L—精氨酸对肉鸡肺动脉压和腹水综合征发生的影响   总被引：6，自引：2，他引：6  
AA肉鸡 180羽随机等分为对照组 (C)和试验组 (A、B)。参试鸡 14日龄前常规饲养。 14日龄后C组鸡继续常规饲养 ;A、B组鸡舍温度按每日 1～ 2℃由 2 5℃逐步降至 12℃ ,同时日粮中添加 1 5mg kg-1三碘甲状腺原氨酸 (T3 )以诱发腹水综合征 ;B组自 14日龄起至试验结束在日粮中再添加 1% (质量分数 )L 精氨酸。分别于 3,4,5 ,6,7周龄测定各组肉鸡肺动脉平均压 (mPAP)、红细胞压积、右心全心比及血浆一氧化氮 (NO)水平 ,并记录腹水发病率。结果发现 :低温添加T3 处理后 ,A组肉鸡腹水发病率增加 ,mPAP在 5周龄时升高 ,右心全心比在 6周龄时升高 ;B组肉鸡腹水发病率明显低于A组 ,血浆NO水平高于A组 (P <0 0 1) ,mPAP在 6周龄时升高 ,右心全心比在 7周龄时升高 ,此变化比A组晚一周出现。上述结果提示 ,日粮添加精氨酸后血浆NO水平升高 ,可能在一定程度上抑制了肺动脉高压的形成 ,因而在一定程度上降低了腹水综合征发病  相似文献   

14.
低能量激光照射免疫学调节效应的研究进展   总被引：5，自引：0，他引：5  
低能量激光照射免疫学调节效应是其生物学调节效应的重要内容之一。随着低能量激光照射生物学调节效应研究的不断深入,其免疫学调节效应也得到越来越为系统的研究,文章主要就低能量激光照射免疫学调节效应的研究进展,包括其效应特点、影响因素及其机理作一系统阐述。  相似文献   

15.
目的观察三维适形放疗(3D-CRT)同步化疗治疗局部晚期非小细胞肺癌(NSCLC)的疗效及不良反应。方法65例患者随机分为放化组(33例)和放疗组(32例)。两组患者均行3D-CRT。放化组分别于放疗第1、4、7周行化疗。观察两组疗效及毒副反应。结果放化组CR、PR分别为18.2%和69.7%,而放疗组分别是6.3%和50.0%。两组CR、RR(CR PR)差异有统计学意义(P<0.05)。放化组和放疗组1、2a生存率分别是69.7%(23/33)、48.5%(16/33)和65.6%(21/32)、28.1%(9/32),两组的1a生存率无明显差异,2a生存率则差异有统计学意义(P<0.05)。放化组白细胞下降、恶心呕吐较放疗组明显(P<0.05)。结论3D-CRT同步化疗治疗局部晚期NSCLC疗效较好,毒副反应患者能耐受,安全可行。  相似文献   

16.
[目的]研究龙葵多糖对小鼠荷宫颈癌(U14)生长的抑制及对荷瘤小鼠免疫调节作用。[方法]MTT法检测龙葵多糖体外对U14细胞增殖的影响;建立U14宫颈癌腹水瘤模型,观察给药后,对腹水型肿瘤的抑制作用和对荷瘤小鼠存活时间的影响;用ELISA法检测龙葵多糖干扰对荷瘤小鼠血清中IL-44和IFN-γ水平的影响。[结果]龙葵多糖体内有显著抑制小鼠宫颈癌U14细胞生长的作用,并且能够显著延长荷瘤小鼠的生命周期。细胞因子检测结果表明,龙葵多糖可显著增加荷瘤小鼠血清IFN-γ水平,显著降低血清中IL-44的水平。[结论]龙葵多糖具有抑制腹水型肿瘤U14生长、延长荷瘤小鼠存活时间的作用,推测该多糖可能是通过激活机体内免疫系统的活动,进而调节细胞因子的分泌而发挥其抗肿瘤作用。  相似文献   

17.
通过检测注射pGRF基因质粒(pig growth hormone-releasing factor gene plasmid)后生长猪血液生化指标与肌肉品质指标,探讨该制剂对生长猪的健康水平、肉品质和安全性的影响。将8头二元杂交、60日龄左右的阉后公猪随机分为两组,一组注射pGRF基因质粒,一组注射等量生理盐水,进行了60 d对比试验,于处理后第7、14、28、56天早晨空腹采血制备血清,测定生化指标。结果表明:注射pGRF基因质粒后第14天,除血清尿素氮提高39.88%外,血糖、尿素氮、肌酐、甘油三酯、胆固醇浓度变化均不显著。由此可见,注射pGRF基因质粒后,除血清尿素氮升高外,生长猪的其他生化指标都没有明显变化。于处理后第60天,每组随机选3头屠宰,称量器官质量,并采样测定肉品质。与对照组相比,试验组猪肉剪切力下降7.28%(P0.05),滴水损失降低20.86%(P0.05),而熟肉率提高4.38%(P0.05);但肌间脂肪比对照组提高68.83%(P0.05);肉色a*值降低14.30%(P0.05),b*、L*值有所提高,但差异均未达到显著水平;pGRF基因质粒对胴体pH影响不明显,器官与胴体的比值差异均未达显著水平(P0.05),其中从平均值看心脏质量比例略有增加,脾、肾比例有所下降。从本试验结果看,注射pGRF基因质粒对各项猪肉品质指标无不良影响,还可改善肌肉嫩度,降低滴水损失和提高肌间脂肪含量。  相似文献   

18.
通过建立种植性肝癌(H22)实体瘤动物模型,并给荷瘤小鼠灌胃含有苦马豆素(swainsonine,SW)且剂量分别为2.7mg/(kg·d)和16.2mg/(kg·d)的豆类丝核菌次级代谢产物稀释液,于灌药后16d剖检荷瘤动物并取肿瘤组织与肝组织制作超薄切片,透射电镜观察。结果表明,该次级代谢产物能抑制种植性实体瘤(H22)的生长和转移。因此,该次级代谢产物具有抗肿瘤药用价值。  相似文献   

19.
以木材苯酚液化物为原料,加入六次甲基四胺合成可用于制备木质碳纤维的纺丝液。利用FTIR考察了合成条件对纺丝液分子结构的影响。结果表明,液固比及升温时间的增加,木材液化物纺丝液红外光谱3 425～3 406cm-1羟基、1 595～1 512cm-1苯环骨架振动特征吸收峰都逐渐减弱,纺丝液分子内形成亚甲基键桥,分子结构初步形成交联结构,但液固比相比升温时间对纺丝液结构的影响要明显。另外,上述区域的吸收峰在合成温度为120℃时减弱达到最大,超过120℃时,木材液化物纺丝液红外光谱随温度的增加变化不大。  相似文献   

20.
 对普洱茶发酵过程翻堆样的红外图谱进行识别,并结合茶多酚的变化对吸收峰进行分析。结果表明,红外图谱中1240,1150cm-1附近的吸收峰相对强度与茶多酚含量相关,1320,1640cm－1附近吸收峰强度与多酚氧化产物含量相关;T1640/T1240,T1640/T1150,T1320/T1240,T1320/T1150透过率相对强度比反映了多酚及其氧化产物相对含量的变化趋势,可为普洱茶发酵程度的判断提供参考。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号