共查询到20条相似文献，搜索用时 218 毫秒
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本文较系统地研究了退化羊草草原上金狗尾草的季节生长动态及其与8种土壤因子的关系,结果表明:金狗尾草在整个生长季节中,其生长主要集中在7～8月,生物量增幅为40.74·g·m~(-2),最大值为90.54g·m~(-2)(8月),土壤pH值、电导率、速效钾和水解氮对金狗尾草生长的影响较小,而土壤含水量、温度、有效磷和土壤活性有机质对其影响较大,是金狗尾草生长的主控因子。 相似文献
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综合研究生长因子对螺旋藻生长的影响,并选取影响比较明显的4种生长因子进行正交试验,结果表明,混合生长因子VBl0.5mg.L-1,VB1220g·L-1有利于螺旋藻的生长。对优化的混合生长因子,结合有机碳源葡萄糖、还原剂Vcc、激素NAA进行进一步正交试验,结论是在Zarrouk溶液基础上,添加葡萄糖1.5g·L-1、VBl250ug·L-1、VB1210ug·L-1、NAA0.5mg·L-1时有利于螺旋藻生长。与自养生长相比,混养培养时生物量增加了118.6%,单位叶绿素a含量减少了6.7%,藻胆蛋白含量增加了34.7%。 相似文献
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为提高棉花黄萎病拮抗细菌HMB-1005的芽孢形成率及芽孢数量,分析摇瓶发酵对芽孢形成的主要影响因素．通过单因素试验和正交试验对HMB-1005菌株产芽孢条件进行分析,确定最佳摇瓶发酵条件为：蔗糖1％、玉米粉2％、CaCl2·2H2O0．02％和NaH2PO4·2H2O0．2％、pH值为7．0、温度为30℃、转速为200r／min、接种量10％、种龄24h。在此优化条件下,发酵液中拮抗菌出芽率达到90％以上． 相似文献
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本文成功地建立了以微晶石蜡柱为固相萃取剂,以2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)为显色剂的固相萃取光度法测定痕量铁的新方法,并采用正交试验法考查了测定条件.方法基于在pH=4.5的缓冲溶液中,铁(Ⅱ)与5-Br-PADAP形成稳定的配合物,在λ=742nm处进行测定,其摩尔吸光系数为ε742=2.61×105L·mol-1·cm-1,检测限为0.218μg·L-1,铁含量在0-0.4μg·mL-1范围内服从比尔定律.该方法用于水样中痕量铁的测定,结果满意. 相似文献
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蛋壳作载体固定化脂肪酶 总被引：4，自引：0，他引：4
研究了蛋壳作载体,吸附交联法固定化脂肪酶的最佳工艺;C_(酶)=0.12g·g~(-1)cor,t_(吸附)=30min,pH_(交联)=6.2,t_(温度)=室温,得到的最大固定化酶活力为29.41U·g_(car)~(-1);并考察了该固定化酶的稳定性:pH=9.0,t=35℃,交联后的固定化酶重复使用6次后活力仍保贸53％。 相似文献
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灵芝原生质体制备与再生条件的研究 总被引：1，自引：0，他引：1
张李阳 《南京晓庄学院学报》2000,(4)
通过不同酶浓度、酶解温度、酶解时间、渗透压稳定剂及菌龄等对灵芝菌丝原生质体制备与再生的影响的研究 ,结果表明 ,菌龄为 60h的菌丝 ,采用浓度为 2 %的溶壁酶以 0 .6M的甘露醇作渗透压稳定剂于pH6.5,31°C下酶解 2h,当酶解液中湿菌体含量对 0 .1g/ml时 ,其原生质体数可达 2 1 0 7个 /ml,且再生率达8.5% 相似文献
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以产没食子酸植物内生真菌CP01菌株为出发菌株,对影响菌体的生长代谢的葡萄糖添加量、培养温度、pH值、摇瓶最佳装液量、代谢前体物(苯丙氨酸)的添加量等因素进行了研究。结果表明:CP01菌株,在菌体培养5d的时候,没食子酸的含量和产量达到最高;葡萄糖含量为20g/L、培养温度为28℃、摇瓶装液量为100mL时,没食子酸的含量和产量达到最高。此外,苯丙氨酸含量为150mg/L时,没食子酸的含量和产量达到最高。 相似文献
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目的:研究优化黑曲霉、乳酸菌、枯草芽孢杆菌及酵母菌等4种混菌混合发酵玉米豆粕型饲料的最佳发酵菌种比例组合.方法:以黑曲霉、乳酸菌、枯草芽孢杆菌及酵母菌为4个因素,每个因素设定3个水平,按照L9(34)正交试验表设计9组不同的菌种比例组合,总接种量按4％,发酵初始水分设定为36％,30℃条件下进行固态发酵,分别发酵48、72、96 h后测定样品pH值、乳酸含量及干物质回收率(DMR),优化其最佳发酵组合.结果:相同发酵时间内,黑曲霉、乳酸菌、枯草芽孢杆菌、酵母菌之比为3:3:2:1时,样品pH值最低,发酵速度最快;相同发酵时间内,黑曲霉、乳酸菌、枯草芽孢杆菌、酵母菌比例为3:3:2:1时,乳酸含量显著高于其他各菌种比例组合(P<0.05);发酵时间为72 h时,干物质回收率各组间无显著性差异(P>0.05),干物质损失在4.60％.结论:本试验条件下,黑曲霉、乳酸菌、枯草芽孢杆菌、酵母菌之比为3:3:2:1时,发酵效果最好. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献