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31.
32.
《酶工程》教学与课程建设的探讨 总被引:5,自引:2,他引:5
酶工程是生物技术专业的主干课程,其主要内容是研究酶的生产和应用。为了使酶工程的教学适合时代发展的需要,培养合格的从事酶工程研究及生产的技术人才,以多年酶工程教学实践为基础,集中介绍该门课程教学与建设的体会及其思考。 相似文献
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Changes and availability of P fractions following 65 years of P application to a calcareous soil in a Mediterranean climate 总被引:4,自引:0,他引:4
The fate and availability of P derived from granular fertilisers in an alkaline Calcarosol soil were examined in a 65-year
field trial in a semi-arid environment (annual rainfall 325 mm). Sequential P fractionation was conducted in the soils collected
from the trial plots receiving 0–12 kg P ha−1crop−1, and the rhizosphere soil after growing wheat (Triticum aestivum L. cv. Yitpi) and chickpea (Cicer arietinum L. cv. Genesis 836) for one or two 60-day cycles in the glasshouse. Increasing long-term P application rate over 65 years
significantly increased all inorganic P (Pi) fractions except HCl–Pi. By contrast, P application did not affect or tended
to decrease organic P (Po) fractions. Increasing P application also increased Olsen-P and resin-P but decreased the P buffer
capacity and sorption maxima. Residual P, Pi and Po fractions accounted for an average of 32, 16 and 52% of total P, respectively.
All soil P fractions including residual P in the rhizosphere soil declined following 60-day growth of either wheat or chickpea.
The decreases were greater in soils with a history of high P application than low P. An exception was water-extractable Po,
which increased following plant growth. Changes in various P fractions in the rhizosphere followed the same pattern for both
plant species. Biomass production and P uptake of the plants grown in the glasshouse correlated positively with the residual
P and inorganic fractions (except HCl–Pi) but negatively with Po in the H2O-, NaOH- and H2SO4-fractions of the original soils. The results suggest that the long-term application of fertiliser P to the calcareous sandy
soil built up residual P and non-labile Pi fractions, but these P fractions are potentially available to crops. 相似文献
35.
医学研究生教育的目的是培养高素质创新型医学人才,创新离不开科研,病理学是多学科科研究工作的基础。建立科研平台提高科研能力是研究生教育十分关注的问题。如何培养研究生病理学实验能力,使学到知识技术在今后的科研活动中得以运用,本文就近几年我们在研究生病理学实验带教实践过程中的一些方法作一介绍。 相似文献
36.
树冠结构参数及附近风场特征的风洞模拟研究 总被引:3,自引:0,他引:3
根据风洞模型实验,分析了树冠结构参数(疏透度β、透风系数α)和际近的风速场特征,结果表明,透风系数与疏透度之间符合幂函数关系α=β^0.6,树冠附近的风速减弱区为椭球形立体空间,减弱区随树高,冠幅的增大而增大,随透风系数(或疏透度)的增大而减小,在水平和垂直剖面上,等风速线分别为椭圆形和椭圆线段。 相似文献
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以快生型大豆根瘤菌HH103菌株为供试菌株,采用单因素碳氮源利用试验和正交设计试验,确定最佳培养基及其配方。结果表明:该菌株在YMA中生长良好,最佳碳源为蔗糖,最佳氮源为酵母膏,最佳培养基成分配方(g/L):蔗糖11,酵母膏0.9,K2HPO4 0.5,MnSO4 0.005,CaCl2 0.1,KH2PO4 0.5,MgSO4 0.2,KNO30.77,(NH4)2HPO4 0.33,FeCl3 0.005,pH 7.2。 相似文献
39.
External phosphorus load to a wetland with two shallow lakes in the Botshol Nature Reserve, the Netherlands, was reduced since 1989, resulting in a rapid reduction of phosphorus levels, phytoplankton biomass and turbidity, and after 4 years, explosive growth of Characeae. The clear water state was unstable, however, and the ecosystem subsequently alternated between clear, high-vegetation and turbid, low-vegetation states. The switch from clear to turbid states occurred at a higher phosphorus level than the switch from turbid to clear states and area covered by macrophytes was significantly correlated to Secchi disc depth (r = 0.86, p < 0.001). Beginning in 1997, phosphorus input from droppings of greylag geese and black-headed gulls increased. The hypothesis that grazing prevented the return of Characeae populations was tested during 1996–1997 using large-scale exclosure experiments. The biomass and cover of Characeae were monitored in 17 exclosures for 2 years. The experiments showed no significant increase in Characeae in the absence of grazers compared with the controls. During the course of the experiments, the entire lake switched from turbid water to clear water and high Chara biomass. These ecosystem developments suggest that light limitation was the main factor controlling the collapse and return of Characeae in Botshol. 相似文献
40.