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991.
992.
The residual effect of 2-year-old swards of clover-ryegrass mixture and ryegrass in monoculture on yield and N uptake in a subsequent winter wheat crop was investigated by use of the 15N dilution method and by mathematical modelling. The amount of N in the wheat crop, derived from clover-ryegrass residues was 25–43% greater than that derived from residues of ryegrass which had been growing in monoculture. Expressed in absolute values, the N uptake in the subsequent winter wheat crop was 23–28 kg N ha −1 greater after clover-ryegrass mixture than after ryegrass in monoculture. Up to about 54 kg N ha−1 of the N mineralised from the clover-ryegrass crop was calculated to be leached, whereas only 11 kg N ha−1 was leached following ryegrass in monoculture. 相似文献
993.
Zhu Tianguo 《保鲜与加工》1991,(2):56-63
The transfer substructure method is extended to application in substructures with different linking ways,thus the field of application of this method is expanded. Its relaibility and efficacy are proved by some examples. 相似文献
994.
The author analyses the advantages and disadvantages of common indirect regulation pricing methods of public utility goods. It is pointed out that it results in high trade-cost and A-J effect binging in an excess of investment when capital yield method be used. It is not reasonable enough in setting PRI-X of PRI-X pricing method. An integrated indirect regulation pricing method is put forward which is to form a two-tier incentive mechanics both in expanding producing ability and improving efficiency. In initial stages of new public project, capital yield method should be used in order to activate investment motive. Upper-limit pricing method should be used in anaphase in order to improve the producing efficiency. 相似文献
995.
The methods of equivalent linearization of different energy dissipation devices are different in analyzing passive energy dissipation structure including different type of energy dissipation device by using of mode-superposition response spectrum method based on equivalent linearization, which results in the differences in computing accuracy and cost in dynamic analysis. For structures separately installed different energy dissipation devices, authors utilize relatively uncoupled mode-superposition method and complex mode-superposition method for contrast analysis, and probe into the suitability of the two methods in the dynamic analysis of passive energy dissipation structure. Numerical results show that complex mode-superposition method could be better for structure with viscous dampers in order to guarantee accuracy, and relatively uncoupled mode-superposition method is recommended for structure with viscoelastic, metallic or frictional ones. 相似文献
996.
In view of color image characteristic, the paper improves the zero algorithm in the application of concrete algorithm, draws a new algorithm-incomplete scanning method, which is applied to color image compression. The authorsconvert color image from the RGB space into luminance-chrominance YUV space, then compress the converted image to encode/decode. Theoretical analysis and simulation experiment indicate that the compression ratio and encoding/decoding speed are increased, at the sase time the quality of restored image is guaranteed. 相似文献
997.
响应面法优化残次枣中不溶性膳食纤维提取工艺 总被引:3,自引:0,他引:3
以残次哈密大枣为原料,采用酶重量法提取不溶性膳食纤维,在单因素试验的基础上,根据Box-Behnken中心组合实验设计原理,以不溶性膳食纤维得率为响应值,设计三因素三水平响应面分析试验,优化残次枣中不溶性膳食纤维的提取工艺参数,同时建立并分析各个因素与对应变量的数学模型。结果表明,提取残次枣不溶性膳食纤维的最佳工艺条件为:α-淀粉酶添加量0.5%,中性蛋白酶添加量0.6%,液料比27∶1,酶解温度50℃,酶解40 min。在此条件下,残次枣中不溶性膳食纤维得率可达13.04%。 相似文献
998.
不同品种紫花苜蓿中总皂苷含量的比较研究 总被引:5,自引:0,他引:5
采用比色法测定了北京地区栽培不同年限的45个紫花苜蓿品种茎、叶中总皂苷的含量。结果表明,各品种苜蓿叶片中的皂苷含量均高于茎,在不同品种之间存在明显差异。4年生植株中皂苷含量最高的品种“Vernal”为1.174%,最低的品种“Empress”为0.606%;3年生植株中最高的品种“WL442”为1.141%,最低的品种“农保”为0.788%;2年生植株中最高的品种“胜利者”为1.293%,最低的品种“全能”为0.722%。综合比较,含量最低品种与最高的品种相差2.13倍。栽培年限对紫花苜蓿皂苷含量具有一定影响。 相似文献
999.
The Sijiaotian Tunnel in Yunnan Dabao Highway lies in the narrow defile landscape,and the engineering geology condition is complex,with plenty of cienega.According to the actual situation of the Sijiaotian Tunnel Project in Yunnan Dabao Highway,the stability of the surrounding rock mass is studied by using a 3-D non-linear FEM.The Drucker-Prager criterion is chosen as the failure criterion of the rock.The relatively dangerous zone and the monitoring points in the tunnel are determined.The numerical results show that the Sijiaotian Tunnel is relatively stable.The conclusion has some significance for guiding the construction of similar projects. 相似文献
1000.
Cassava root rot disease is an increasing problem in Africa where yield losses of about 80% have been recorded. We evaluated
290 African landraces and 306 improved genotypes from the germplasm collections of the International Institute of Tropical
Agriculture (IITA), for sources of resistance using root slice laboratory assay. Disease severity was assessed quantitatively
by direct percentage estimation (PS) and by use of a rating scale (RS). Both methods of assessment were compared for identification
of variability in the germplasm, and genotypes were classified into response groups using an enlarged rank-sum method that
combined the PS and RS assessments. The two scoring methods revealed continuous variation (P < 0.001) for resistance in the sets of germplasm. Disease assessments based on PS and RS were highly correlated in both the
improved germplasm (r = 0.75) and the landraces (r = 0.72). Based on PS assessment, 50 improved genotypes (16.3%) and 53 landraces (18.3%) showed significantly lower disease
scores than the resistant control. The rank-sum method separated each set of collections into highly resistant, resistant,
moderately resistant, moderately susceptible, susceptible and highly susceptible groups. Fifty-nine improved genotypes (16.4%)
and 61 African landraces (16.9%) were identified as either highly resistant or resistant. Generally, these genotypes exhibited
resistance by limiting the growth of the pathogen (reduced amount of invaded surface area). This type of rate-reducing resistance
is highly heritable and a quantitative trait which can be harnessed in breeding. Genotypes subsets were identified for further
studies into the genetic basis of resistance to root rot disease. 相似文献