桂林岩溶石山光蜡树响应曲线的研究     

杨红兰  梁士楚  黄雅丽  田华丽 《安徽农业科学》2012,40(34):16505-16506,16512

[目的]为掌握光蜡树生理生态性。[方法]采用LI-6400型便携式光合仪,对光蜡树群落中光蜡树的响应曲线进行了研究。[结果]光蜡树在8月具有较高的光饱和点和较低的光补偿点,有利于光蜡树对岩溶石山环境的适应;11月光蜡树的光饱和点降低而光补偿点升高。光蜡树8月份的羧化效率为0.04,11月的较低仅为0.01。[结论]光蜡树对弱光环境具有一定的适应机制,且它对弱光的利用能力强。  相似文献   

我国农村人力资本投资优化对策分析   总被引：1，自引：0，他引：1  

张俊霞  韩阳 《安徽农业科学》2012,(18):9912-9913,9926

根据相关统计公报数据,分析了我国农村人力资本投资现状,总结了我国农村人力资本投资存在的问题,提出了我国农村人力资投资的优化对策:一是强化对农村人力资本投资的认识;二是发挥政府在人力资本投资中的主体作用;三是增加农村基础教育投入;四是加大对农民的培训力度;五是增加对农村医疗卫生保健事业的投资。  相似文献   

水分胁迫对异株荨麻光响应特性的影响   总被引：2，自引：0，他引：2  

何斌  刘勇 《吉林农业大学学报》2012,34(2):125-129

采用盆栽试验研究了土壤饱和含水量为100％、70％、60％及40％条件下,异株荨麻的光合作用—光响应特性.结果表明:非直角双曲线模型能很好地拟合异株荨麻的光合作用—光响应曲线;净光合速率在同等光合有效辐射时基本上表现为T2＞T3＞T1＞T4;异株荨麻叶片的表观量子效率、最大净光合速率、暗呼吸速率和光饱和点均在适度水分胁迫下达到最大,在重度干旱胁迫下最低,这说明适度水分胁迫有助于提高异株荨麻对光能的利用能力.  相似文献   

3个油茶新品种的光合特性     

袁军  谭晓风  姜志娜  杨巧丽  李泽 《浙江林学院学报》2012,29(4):527-532

采用LI-6400便携式光合测定系统,对3个油茶Camellia oleifera新品种‘华硕’‘华金’‘华鑫’的光合生理指标及叶绿素质量分数进行测定.结果表明:①3个油茶品种叶片的净光合速率(P(I))日变化均呈宽大的单峰型,不存在光合午休现象,9:00时达到最大值.②‘华硕’‘华金’‘华鑫’的光补偿点分别是43.81,58.49和54.24μmol·m-2·s-1,光饱和点分别是693.2,638.8和684.85 μmol·m-·s-1,对光强的适应范围大小为‘华硕’＞‘华鑫’＞‘华金’.③‘华硕’‘华金’‘华鑫’的总叶绿素质量分数分别为1.35,0.97和0.90 mg·g-1.净光合速率与叶绿素a呈极显著负相关关系(P＜0.01),相关系数为-0.947;与叶绿素b,总叶绿素质量分数和叶绿素a/叶绿素b之间相关性不显著.综合净光合速率(P(0)),表观量子效率(AQY)和叶绿素质量分数等可知“华硕”和“华鑫”的光合性能较强.  相似文献   

Numerical Analysis on Bearing Capacity of Piles Subjected to Side Loads     

YAO Wenjuan  CHEN Shangping  CHEN Jie  CHENG Zekun 《保鲜与加工》2012,(4):6-11

Besides the loading applied by the upper building, the piles are often subjected to indirect loading such as side loads. These kinds of loads would cause the pile bear additional force (negative skin friction), which may be large enough to reduce the bearing capacity and cause structural failure of a pile. By establishing the numerical model of pile soil interaction, the bearing capability of pile under side load was analyzed. The joint effect of different magnitude and the distance of the side load on the skin friction were focused. The joint effect of length of the pile and the distance of side load on the skin friction was discussed. The expression of the two combination relationship was obtained. Meanwhile, by using the least square method, the expression of total skin friction on different side load combination was achieved. And based on the statistical analysis of the dispersion coefficient, the function expression was proved to be of high precision. The results show that when k, which indicates the relative relation of side load distance s and the side load magnitude Q, increases to 32, the value of negative skin friction goes to zero. When c, indicating the relative relation between pile length L and side load distance s, increases to 0.5, the value of negative skin friction goes to zero. Beyond limit value of these two relative relationships, the bearing capability of the pile will not be affected by side loads.  相似文献   

我国农业资金投入对抗灾能力的效应分析     

姚寿福 《农业现代化研究》2012,33(2):161-165

本文分析了我国农业资金投入和农业气象灾害、抗灾能力的历史与现状;采用定性与定量相结合、相关与回归分析方法,对我国农业资金投入、水利设施建设对粮食生产的影响效应,各种农业资金投入对农业水利设施建设的效应进行了实证分析。结果表明:除水库数量外,农业资金投入与水利设施对粮食生产有显著影响,农业资金投入对水利设施也具有明显的正向效应,因此增加资金投入是提高农业抗灾能力、保障粮食安全的重要保证;并就农业水利建设的优先次序提出了建议。  相似文献   

Phytate and phytase in fish nutrition     

Kumar V  Sinha AK  Makkar HP  De Boeck G  Becker K 《Journal of animal physiology and animal nutrition》2012,96(3):335-364

Phytate formed during maturation of plant seeds and grains is a common constituent of plant-derived fish feed. Phytate-bound phosphorus (P) is not available to gastric or agastric fish. A major concern about the presence of phytate in the aquafeed is its negative effect on growth performance, nutrient and energy utilization, and mineral uptake. Bound phytate-P, can be effectively converted to available-P by phytase. During the last decade, phytase has been used by aqua feed industries to enhance the growth performance, nutrient utilization and bioavailability of macro and micro minerals in fish and also to reduce the P pollution into the aquatic environment. Phytase activity is highly dependent on the pH of the fish gut. Unlike mammals, fish are either gastric or agastric, and hence, the action of dietary phytase varies from species to species. In comparison to poultry and swine production, the use of phytase in fish feed is still in an unproven stage. This review discusses effects of phytate on fish, dephytinisation processes, phytase and pathway for phytate degradation, phytase production systems, mode of phytase application, bioefficacy of phytase, effects of phytase on growth performance, nutrient utilization and aquatic environment pollution, and optimum dosage of phytase in fish diets.  相似文献   

Feline parathyroid hormone: validation of hormonal assays and dynamics of secretion     

Pineda C  Aguilera-Tejero E  Raya AI  Diez E  Rodriguez M  Lopez I 《Domestic animal endocrinology》2012,42(4):256-264

Validated assays for quantification of intact parathyroid hormone (I-PTH) are no longer available. Moreover, the third-generation PTH assay that only detects the whole PTH molecule (W-PTH) has never been tested in cats. The work presented here is aimed to validate a commercially available assay for measurement of I-PTH and W-PTH in cats and to study the dynamics of PTH secretion in healthy cats. Our results show that both assays are reliable for the measurement of feline PTH. In healthy adult cats W-PTH concentration (15.1 ± 1.6 pg/mL) was greater (P < 0.001) than I-PTH concentration (9.1 ± 0.7 pg/mL). The dynamics of PTH secretion in response to changes in extracellular calcium (Ca(2+)) were investigated in 13 cats by studying PTH-Ca(2+) curves. PTH-Ca(2+) curves were obtained by intravenous infusion of disodium ethylenediaminetetraacetic acid and CaCl(2). PTH was measured using both I-PTH and W-PTH assays. During hypocalcemia a sigmoidal curve that was similar when measured with I-PTH or W-PTH was obtained. The maximal PTH concentration in response to hypocalcemia was greater with W-PTH (179.6 ± 41.9 pg/mL) than with I-PTH (67.6 ± 10.5 pg/mL; P = 0.01). However, hypercalcemia resulted in an equivalent PTH inhibition, with both assays yielding PTH concentrations as follows: W-PTH = 4.0 ± 0.4 pg/mL and I-PTH = 4.9 ± 0.3 pg/mL (NS). Parameters of the feline PTH-Ca(2+) curve are similar to what has been previously reported in dogs.  相似文献   

旋切单板的长度计算     

张亮  刘渝 《林业机械与木工设备》2012,(12):37-40

提出了两种精确计算旋切单板长度的数学方法：①分析刀具在原木上的旋切曲线,通过对旋切曲线的积分计算单板长度;②计算原木段端面的单板面积,通过面积计算单板长度。借助Microsoft Mathematics软件对两种算法进行对比分析,结果表明给出的算法准确可靠,可供实际生产和相关科研参考。  相似文献   

低能离子注入法诱变选育纤维素酶产生菌的研究     

张宁  蒋剑春  杨静  卫民  赵剑  童娅娟 《林产化学与工业》2012,32(5)

以纤维素酶产生菌里氏木霉(Trichoderma reesei)为实验菌株,研究了低能N+注入对T.reesei存活率、菌体总抗氧化能力(T-AOC)、蛋白质含量以及产酶能力的影响.结果表明,T.reesei经N+注入后存活率曲线呈现“双马鞍型”,这与离子注入典型的“马鞍型”曲线不同.菌体总抗氧化能力与注量之间的关系曲线同样在1.50×1016和2.50×1016 cm-2注量处呈现两个峰,与存活率曲线的变化趋势一致.由此推测,离子注入微生物所诱导的总抗氧化能力的强弱变化很有可能决定微生物的存活情况.实验通过诱变筛选得到3株纤维素酶高产菌株150-1,150-2和250-6,高产菌株纤维素酶的平均活力比出发菌株提高24.3％,均表现出很强的发酵积累纤维素酶的能力,尤其在发酵后期更为突出.  相似文献