共查询到20条相似文献，搜索用时 171 毫秒
1.
苯磺隆、苄嘧磺隆对不同小麦品种安全性及叶绿素含量的影响 总被引：8，自引：0，他引：8
室内土壤滴浇法测定了苯磺隆、苄嘧磺隆对不同小麦品种的安全性和叶绿素含量的变化,结果表明：两种药剂对不同小麦品种的安全性存在较大差异,且对根长的抑制作用明显大于株高;对叶绿素含量的影响与对株高的影响结果一致。苯磺隆对周麦13的根和芽敏感,使用不当易产生药害;对偃师4110根长最安全,株高最敏感。苄嘧磺隆对高优503根长最安全,株高最敏感;对周麦13株高最安全,根长最敏感。因此,小麦田化学除草应根据不同小麦品种来选择除草剂品种、有效用量和最佳施药方法。 相似文献
2.
油茶气象影响指标研究综述 总被引：2，自引：0，他引：2
基于收集到的近百篇与气象条件有关的油茶研究文献和出版书籍,进行气象条件对油茶生产影响的归类统计,其结果可分为3类,即油茶种植气候适宜性指标、油茶产量气象条件的影响指标、油茶气象灾害指标。油茶种植气候适宜性指标及条件为：（1）年平均气温14~21℃,最适宜温度为16~21℃,极端最低气温-10℃,极端最高气温40℃,最冷月平均气温0℃以上,最热月平均气温31℃以下,年无霜期大于200天,≥10℃积温为4000~7000℃·d,最适宜的≥10℃积温为5000~7000℃·d;（2）年降水量1000~ 2200 mm,最适宜年降水量为1200~1800 mm;相对湿度74%~85%;（3）年日照时数1500~2200 h,年日照百分率35%以上。油茶产量适宜性气象指标及条件为：（1）春梢生长期适宜的平均气温为10~20℃;（2）花芽分化期适宜的平均气温为24~33℃,最适宜平均气温为27~33℃,日平均日照时数在10 h以上;花期适宜的平均气温为10~20℃,最适宜平均气温为14~18℃,盛花期雨日小于13天,日照大于100 h;（3）果实生长期适宜的平均气温为25~30℃,降水量在200 mm以上,最适宜降水量为450~550 mm;（4）油脂累积期适宜的平均气温为16~23℃,降水量在100 mm以上,最适宜降水量为150~200 mm,高温日数小于20天。油茶主要气象灾害有：低温冷冻害、连阴雨、高温干旱、冰雹和大风。 相似文献
3.
印楝素强化浸提试验研究 总被引：1，自引：0，他引：1
印楝素为热敏性差的物质,印楝种子含油率高达20%,需在低温和强化条件下浸出。试验表明,浸前是否榨油对印楝浸出速度无明显影响,在超声波强化浸出条件下,40min的浸出率相当于常规2h的浸出率。若浸出时间都为2h,应用超声波强化浸出印楝素的浸出率高达95%,而常规浸出印楝素的浸出率只有84%,超声波强化浸出的效果非常显著。 相似文献
4.
It is possible to get high compression rate for the interrelationship between neighboring frames of moving pictures. The kernel of research on video compression is that the efficient image compression algorithm is adopted while the interrelationship between neighboring frames and time consumption is concerned to improve the compression efficiency. It is significant that motion compensation is applied to video compression, nevertheless it is too time consuming. A vector coding method based on wavelet transform is presented to avoid searching procedure of motion compensation. Simulation shows that high compression rate is achieved with less time consumption. 相似文献
5.
冀西北高原不同植被的土壤水分动态变化研究 总被引：1，自引：1，他引：1
冀西北高原为高寒半干旱地区,降水是此地区土壤水分的唯一给源,研究土壤水分的动态变化对高效利用降雨有至关重要的作用。研究采用定点观测的方法,对不同植被土壤含水量的动态变化进行了比较研究。结果表明,3种植被生长期内不同土层土壤水分变化存在差异。生长前期,3种植被0￣30cm土层土壤含水量,农田耕翻地最高,水分条件最好,人工草地与退耕还林地互有高低,30￣60cm土层退耕还林地最高,人工草地最少。生长前期,农田耕翻地表层土壤水分较好,能满足春季作物生长要求。生长中期,0￣30cm土层农田耕翻地最低,人工草地与退耕还林地互有高低。30￣60cm土层农田耕翻地最高,人工草地最低。生长后期,0￣60cm土层农田耕翻地土壤含水量最高;人工草地土壤含水量与退耕还林地相比较,0￣40cm土层差异不大,40￣60cm土层退耕还林地高于人工草地。 相似文献
6.
Peng Donglin 《保鲜与加工》1996,(2):95-98
A new idea "Pretreatment and cycle stream of control" and the scheme to put it into practice is presented. In space region,the circuit is designed to form chain and cycle,and in time region,the program is designed to distinguish the period and the instant.It is ensured that the pretreatment will be finished in the period and there is always a circuit to wait to the triggered at the instant. So the respond speed of the system is almost approximate to that one of trigger circuit. 相似文献
7.
采用浸渍法制备CaO/MgO固体碱催化剂,并应用于菜籽油与甲醇的酯交换反应制备生物柴油。考察了镁钙比对CaO/MgO催化活性的影响。试验表明,用质量分数22.6%的乙酸钙浸渍MgO,镁钙摩尔比为3～4时最接近等体积浸渍,镁钙摩尔比为1~2时为过量浸渍。镁钙摩尔比越低,催化剂活性越高,但镁钙摩尔比低于3时,催化剂活性组分分布不均匀,且活性增加不明显。所以最佳镁钙摩尔比为3～4。 相似文献
8.
A model of credit quantitative measurement and management widely used in foreign countries is introduced, and its limitation which appears while the model is used in China is analyzed. According to the chaos time serials constituted by various period credit grades' transition probability of an enterprise and the average value of its ratio of callback due to breach of faith, applying the theory of the chaos time serials and the local prediction method, a credit grades' transition matrix and a matrix of the average ratio of callback due to breach of faith is established. Which is applied to Chinese enterprises. Thus, a credit risk quantitative measurement and management model which is adapted to commercial bank is established, which is important in theory and practice. 相似文献
9.
XIANG Yu min 《保鲜与加工》2001,(5):81-83
Based upon the anisotropy of electric polarization,the nonolinear oscillation equation of the ellipsoid in electric field is constructed by considering the rotative moment between electric field and the induced dipole moment on metallic ellipsoid of field intensity gauge. The oscillation period relative to the amplitude and electric intensity is calculated.An expression of exact computation to measure the electric field intensity is achieved.The impact of the amplitude parameter upon the experiment calculation is analyzed and the method to determine the amplitude is contributed.A contrast to the computed resuls by means of linear oscillation is undertaken to show the raising effect to the calculation precision by considering nonlinearity in oscillation. 相似文献
10.
Deon D. Stuthman 《Euphytica》2002,124(2):253-258
Durable disease resistance and sustainable agriculture are two important concepts that have not been defined well enough for
many people to determine with certainty whether a particular entity fits into either category. While there is not agreement
on either definition, there is little disagreement that each concept is a desirable objective. Ironically, both concepts can
be reduced to `over a long period of time'. While most people would not argue with the indefinite characterization of either
concept, disagreement quickly arises when consideration begins of how to achieve either. Most disease resistance that is rendered
ineffective is race specific. The pathogen population is shifted genetically to defeat the resistance gene. When resistance
is only partial, the population shifts are less likely to occur. Equally so, the more complex the genetics of the resistance,
the more difficult it is for the pathogen to evolve to a form that can overcome the resistance. Throughout history, there
are countless examples of major losses of crops when previous effective resistance has been rendered ineffective, causing
severe hardship and even devastating famines, e.g., Irish potato famine. Fortunately, there are also examples of resistance
that has given protection over an extended time, one is rust in maize. Ultimately, adding genetic complexity to many host
plant resistances is likely to extend their effectiveness (greater durability). Similarly, adding biodiversity to the landscape
for both plants and animals is likely to increase the resiliency of the ecosystem involved. In both cases, the derived food
system will be more secure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
逐日降水量的模拟及其在作物气候风险分析中的应用 总被引：3，自引：0，他引：3
利用天气发生器(NCC/RCG_WG)模拟了安阳200年的逐日降水序列,并通过对模拟结果与1961-2000年实测资料的对比分析表明,模拟结果的均值及概率分布与实际值接近,可用于进一步对降水资源与风险进行分析。对棉花与降水关系的分析表明,华北地区棉花生长季降水满足程度较高,平均能满足棉花生长需要。生育初期的6月干旱出现的机率大,7月和8月水分满足程度高但也有少数年份会出现干旱或者涝渍,9月和10月以干旱为主。对于小麦生产,华北地区降水规律与小麦需求不匹配,除10月和11月基本能够满足外,其余各月均不能满足需要,且缺水严重,生长季降水只能满足小麦需水量的1/3,生长关键期的4月和5月的降水量只能满足需水量的20%~25%。华北地区的小麦生产生长季缺水,按目前的播种面积,华北地区小麦生长季年均麦田缺水300亿m3以上。 相似文献
12.
Base on the existing step-by-step structural damage diagnosis method, a three-step structural damage diagnosis method is developed. According to the analysis of the characteristic of genetic algorithm, a new idea of excluding the undamaged element by means of step-by-step evaluation is developed to deal with the damage diagnosis problem. In this method, sensitivity genetic algorithm is used to exclude the undamaged element step by step and residual force method is used to fix the damage district. According to the simulation research of a 2D framed structure, it is shown that the step-by-step structural damage diagnosis method can gain the ideal results when it's difficult for a single damage diagnosis method to get the good results. It is also indicated that sensitivity genetic algorithm is a good way to exclude the undamaged element step by step. 相似文献
13.
The method to polygon' intersection is applied in computational geometry, computer graphics, GIS, evaluation of geo-hazards and civil engineering. Based on the node state of polygon, the authors propose the method and algorithm of polygon' intersection, the key to which is node operation. This method's concept is simple; and it is easy to computer program's implementation. It avoids to singular problem of Boolean Operation, and is easy to solve the problem of overlapping side and sides intersecting in node of polygon. For the arbitrary way of intersecting of arbitrary solid polygon, this method is accurate and general. 相似文献
14.
迷迭香扦插育苗试验初报 总被引：2，自引：0，他引：2
迷迭香（Rosmarinus officinalis L.）是唇形花科迷迭香属植物,是一种多年生常绿亚灌木,为观赏及芳香油植物,该植物已成为全球普遍重视的资源植物之一。迷迭香种子发育不良,种子萌发力极低,故通常采用无性繁殖法育苗,在生产中为了降低成本,节约资金,现阶段主要采用扦插法繁殖进行苗木生产。近年来,国内外对于迷迭香精油及抗氧化剂的研究报道及论文很多,但对迷迭香育苗技术报道却较少。开展该课题研究,对迷迭香的育苗技术进行研究,通过试验记载、观察、田间管理,为迷迭香种植提高育苗成效,降低成本,增加农民收入,为中国天然抗氧化剂的生产保障优质充足原料供应,具有重要意义。试验研究在玉溪对迷迭香进行扦插试验。迷迭香分别扦插在基质为菜园土的苗床上、用纸杯装菜园土扦插、在泥炭土:珍珠岩为2:1的基质上扦插,试验结果表明,试验结果表明,春季扦插成活率高,成活时间短,扦插苗生长健壮,在菜园土上扦插成本低,用纸杯装土扦插,成活率95%~99%,且苗生长健壮。在泥炭土:珍珠岩为2:1的基质上扦插结果,嫩梢作插穗在插后8d开始生根,25d全部生根,生根率99.5%。以上各种扦插方法培养的扦插苗移栽成活率均在95%以上,没有明显区别,可见3种方法扦插育苗都具有成活率高的特点,但采取什么方法,以成本和已有的生产材料及技术而定。 相似文献
15.
选用以IR64为受体的抗旱基因聚合杂交后代的147个新品系为材料,以水作为对照,研究了旱作对稻米蒸煮品质的影响。结果表明：总体上旱作处理下抗旱新品系的胶稠度比水作处理下低,胶稠度越高的品系,旱作胶稠度降低越大;旱作处理下的碱消值比水作的高,碱消值越高的品系,旱作和水作处理下的差别越小;旱作处理下的直链淀粉含量比水作处理下低,随着直链淀粉含量的增加,旱作和水作的差别越大,但在AC较低时,旱作条件下比水作条件下稍高。在糊化温度和直链淀粉含量两性状上,旱作对改善品质是有利的,对胶稠度不利,不过胶稠度较高的品系中也有个别品系旱作处理的胶稠度比水作的相近或稍高,这些品系有望育成抗旱新品种作为旱作品种推广。 相似文献
16.
MIAO Zeng-hua~ 《保鲜与加工》2004,(6):85-88
In the smart bar-beam structure with piezoelectric strain actuator active control function to vibration, the thickness effect of paste layer is considered and strain is assumed linear distribution along the thickness direction of each layer. The piezoelectric actuator point force model of Crawley and Luis is refined, a more general point force model is established to the smart beam with strain actuator. Point force model calculation formula is educed to smart beam with two-side symmetry paste actuator or one-side paste actuator. The computer simulation is done and the result reveals modified point model is right. The modified model is more common, as is important to design piezoelectric smart structure. 相似文献
17.
The 2D motif method is a surface characterization method promising to separate roughness and waviness from a profile and is adopted by ISO,so is meaningful to extend this method to 3D.Vincent's watershed algorithm is employed for the generation of 3D-motif.A smallest area selecting criteria is proposed for the use of clearing the small motifs which are concerned as noise.As there are no manipulating factors as 2D-method,a multi-scale analysis is employed based on area and depth criteria,the use of depth criteria is to prevent the combination of two adjacent motifs if there is a significant peak on the border of them.Finally the surface of C(100) are analyzed by the presented method,the texture of this surface has been characterized. 相似文献
18.
It is the major way to form a civil engineering contract by means of bidding and tendering passing through the following steps as: tendering, bidding, bid opening, evaluation, acceptance and contract signing. The legal nature of the bid is an invitation to offer. The bid has certain legal binding which is different from the ordinary invitation to offer. The legal nature of the tendering is an order, which is sent to the inviter by the bidder. The letter of acceptance takes effect when it is issued and meanwhile the civil engineering contract is formed. 相似文献
19.
The two-level handstand pendulum system based on fuzzy control is designed. It is impossible to adopt classical control theory, for the mathematical modeling of the system is nonlinear, the fuzzy control is proposed to improve the former linear control algorithms. For the key to fuzzy control is control rule, it becomes most important to design suitable fuzzy rules. Two methods, one based on experience and the other based on system simulation, are presented to set u Pan effective rule base. The practice proves that the control result is of well stability. A control example for two-level handstand pendulum system shows that the control law is efficient and more robust than the classical state feedback optimal control law with respect to errors produced by the external disturbances. 相似文献
20.
it is necessary to balance the failure risk and the maintenance expensive. A methodology for reliability based maintenance optimization of steel bridge welded joints subjected to fatigue is proposed considering linear elastic fracture mechanics (LEFM), the structure reliability, life cycle cost method and maintenance strategies. The maintenance cost is divided into inspection, repair and failure sections according to the whole life cycle cost methodology. And the maintenance strategy is transformed to the minimum expected lifetime costs with a constraint of the minimum acceptable reliability index. An case concerning to a transverse stiffener of bottom flange welded joint of Qingcaobei bridge is studied with a certain number of simplifications. Some sensitivity analysis is provided. Among all the parameters, discount rate is the most remarkable. 相似文献