水稻“3414”肥效试验初报

2008年在汉中市开展了水稻测土配方施肥"3414"试验,结果表明:水稻的最佳经济肥料施用量为纯N 8.0 kg/666.67 m2、P2O5 4.1kg/666.67 m2、K2O 5.1 kg/666.67 m2。     

汉中地区油菜“3414”肥效试验

进行了油菜"3414"肥效试验,结果表明:油菜产量随着氮、磷、钾施用量的增加而增大,但当肥料施用量超过N 15.65 kg/666.67 m2,P2O5 5.97 kg/666.67 m2,K2O 3.75 kg/666.67 m2时,油菜的产量随着施肥量的增大而减小。各处理中,产量最高的为N2P2K1。     

茶陵县早稻“3415”回归设计施肥模型研究

选择茶陵县舲舫乡垸井村和塘冲村两个试验点,应用"3415"(3个肥料要素4个施肥水平15个处理)回归设计进行了两个早稻品种的肥效试验,获得两个肥效函数方程.试验结果表明,早稻的最佳经济用肥量为N 135 kg/hm~2,P_2O_5 72 kg/hm~2,K_2O67.5 kg/hm~2.三要素中N的肥效最大,是制约早稻产量的主要因素,P、K肥效排在其后,P、K肥效排序还受土壤肥力影响.     

How the CCA-adding enzyme selects adenine over cytosine at position 76 of tRNA

CCA-adding enzymes [ATP(CTP):tRNA nucleotidyltransferases] add CCA onto the 3' end of transfer RNA (tRNA) precursors without using a nucleic acid template. Although the mechanism by which cytosine (C) is selected at position 75 of tRNA has been established, the mechanism by which adenine (A) is selected at position 76 remains elusive. Here, we report five cocrystal structures of the enzyme complexed with both a tRNA mimic and nucleoside triphosphates under catalytically active conditions. These structures suggest that adenosine 5'-monophosphate is incorporated onto the A76 position of the tRNA via a carboxylate-assisted, one-metal-ion mechanism with aspartate 110 functioning as a general base. The discrimination against incorporation of cytidine 5'-triphosphate (CTP) at position 76 arises from improper placement of the α phosphate of the incoming CTP, which results from the interaction of C with arginine 224 and prevents the nucleophilic attack by the 3' hydroxyl group of cytidine75.     

马铃薯“3414”肥效试验

马铃薯施用N、P、K肥"3414"肥效试验表明,在厦门市翔安区当地试验条件下,N、P、K肥均影响马铃薯产量,且N、K肥对产量的影响较P肥大;通过建立回归方程并对回归方程进行分析显示,马铃薯产量与N、P、K施肥量之间存在显著的三元二次回归(F=8.1025F0.05=5.9988;R=0.9737**)关系,推荐N肥马铃薯最高经济产量施肥量为277.64 kg.hm-2,N∶P2O5∶K2O=1∶0.24∶1.93,最高经济产量36657.24 kg.hm-2;N肥最佳经济效益施肥量为229.32 kg.hm-2,N∶P2O5∶K2O=1∶0.30∶1.85,最佳经济效益为36285.41元.hm-2。     

茄子“3414”肥料效应田间试验

从“3414”回归最优设计原理设置的茄子肥效试验数据,获得三元肥料效应函数方程,由此数学模型得出理论氮磷钾最佳施肥量配方为N24．23kg／667m^2,P2O54．70kg／667m^2和K2O17．12kg／667m^2,可获得最佳产量3626．77kg／667m^2。综合分析本试验结果,结合当地农业生产实际,氮磷钾建议推荐施用量分别为25kg／667m^2、6kg／667m^2和20kg／667m^2。     

油菜"3414"肥料效应试验研究

[目的]获得安庆市大观区油菜作物在不同肥力水平条件下的推荐施肥量。[方法]通过"3414"回归最优设计原理,设置甘蓝型油菜作物的肥料田间试验。[结果]甘蓝型油菜"3414"试验得出的最佳施肥量是N 131.70~399.90 kg/hm~2、P_2O_547.85~326.85 kg/hm~2、K_2O 77.55~320.25 kg/hm~2。[结论]结合大观区当地实际,油菜推荐施肥量是N 180~360 kg/hm~2、P_2O_5120~150 kg/hm~2、K_2O 150~180 kg/hm~2。     

Crystal structure of ethylene di-11-bromoundecanoate

Ethylene di-11-bromoundecanoate, C(24)H(44)Br(2)O(4), was synthesized as a model for the hydrophobic moiety of saturated phospholipids. The crystals are monoclinic, space group P2(1)/a, with two molecules per unit cell. Unlike folded configurations proposed for phospholipids in biological membranes, the hydrocarbon chains of this diester are fully extended in the crystalline state.     

Structure of a dinucleotide: thymidylyl-(5'-3')-thymidylate-5' (pTpT)

The crystal and molecular structure of the naturally occurring deoxyribose dinucleotide sodium thymidylyl-(5'-->3')-thymidylate-5' has been determined by x-ray diffraction. There are four molecules of dinucleotide and 52 water molecules in an orthorhombic unit cell of dimensions (in angstroms) a = 16.06, b = 15.13, c = 15.65, space group P2(1)2(1)2. There is a very high degree of conformational consistency between the two halves of the molecule when the dinucleotide is viewed as the combination of two 5'-mononucleotides. The planes of the two thymines are not parallel, but are tilted 38 degrees with respect to each other. An extensive system of hydrogen bonding exists involving the bases, waters, phosphates, and sodiums; no base-base hydrogen bonding occurs. The dinucleotide structural parameters should be of assistance in interpreting DNA fiber diagrams in terms of possible structures.     

Cyclic cytidine 2',3'-phosphate: molecular structure

Monoclinic crystals of the sodium salt of cytidine 2',3'-phosphate contain two anions in the asymmetric unit. Both bases are in the syn conformation, and the nucleotides are stacked together into an antiparallel stranded ribbon with the bases 3.3 angstroms apart. One ribose ring is planar, and the other has oxygen-1' puckered toward carbon-5'. The phosphorus atoms in the five-membered ester rings are puckered toward the sugars. The conformations about the carbon-4'-carbon-5' bonds are gauche-trans and gauche-gauche.     

珠芽魔芋“3414”肥料效应试验初报

在湖北主要魔芋产区恩施市开展"3414"肥效试验,初步研究了不同氮磷钾配方施肥对珠芽魔芋(Amorphophallus bulbifer)产量的影响,并成功拟合建立了产量三元二次和一元二次肥料效应方程。结果表明,合理的氮磷钾肥施用量可显著提高魔芋产量,施肥量不足或过量施肥会导致魔芋产量降低;在试验地力土壤条件下,珠芽魔芋最高产量为40 863.4 kg/hm2,此时N、P2O5、K2O的施用量分别为295.1、76.5、193.5 kg/hm2;珠芽魔芋最佳经济产量为40 863.0 kg/hm2,N、P2O5、K2O的施用量分别为290.1、75.5、189.0 kg/hm2。     

仙景槟榔芋"3414"肥效试验初探

采用"3414"完全实施方案开展仙景槟榔芋肥效试验,结果表明:在试验的土壤肥力条件下,钾素对仙景槟榔芋产量影响最大,且施用硫酸钾比氯化钾增产明显;每667 m2施用N 33.6kg、P2O5 11.4kg、K2O 47.0kg,仙景槟榔芋产量最高.     

结球甘蓝“3414”肥料效应试验

以结球甘蓝京丰1号为试验材料,采用“3414”试验设计方案,探索氮、磷、钾肥对结球甘蓝产量的影响和最佳配方施肥量.结果表明,高肥力地块试验施N 259.5 kg/hm2、P2O5 135.0 kg/hm2、K2O 299.6kg/hm2,结球甘蓝可获得73 556.9 kg/hm2的产量;中肥力地块试验施N 193.2 kg/hm2、P2O5 83.6 kg/hm2、K2O 192.2 kg/hm2,结球甘蓝可获得61 167.3 kg/hm2的产量.     

"3414"肥料试验对超级稻产量的影响

为取得有关施肥参数,建立超级稻施肥模型,应用"3414"设计方案对超级稻两优培九进行田间肥效试验,研究不同配方施肥对其产量的影响。结果表明,氮、磷、钾配施,以施肥量高的处理产量相对较高;在一定范围内,氮、磷、钾肥的施用量对超级稻的增产作用是氮肥大于钾肥,钾肥大于磷肥。建议玉林市超级稻氮、磷、钾施用量分别为N 240.0kg/hm2、P2O590.0kg/hm2、K2O 255.0kg/hm2。同时要掌握好施肥时期和比例,特别是后期适宜施氮,保证超级稻各个生长期所需氮素。     

番茄“3414”试验初报

本文通过"3414"试验,研究平谷区番茄的合理施肥量,分析传统施肥存在的问题。结果表明,三元二次方程不显著,一元函数推荐的最大施肥量为纯N132kg/hm2,为传统施肥量的3.2倍,P、K肥可以不施。     

高桥地区圆葱“3414”肥效试验研究

[目的]为今后指导圆葱合理施肥提供理论依据。[方法]试验采用二次回归"3414"完全方案设计,对高桥地区圆葱植株的氮、磷、钾含量及产量进行了分析。[结果]通过田间试验建立了圆葱的肥料效应函数模型,得出了最佳经济产量、最佳施肥量及其比例。其中,氮、磷、钾最佳经济产量为71 520 kg/hm2,最佳施肥量为N169.50 kg/hm2,P2O5 106.50 kg/hm2,K2O57.00 kg/hm2,NP∶2O5∶K2O比例为1∶0.630∶.34较为合理的。氮、磷、钾三要素中,氮肥对圆葱产量作用最大,依次是磷肥、钾肥。另外确定了一些重要的施肥参数。100 kg鳞茎养分需求量为N 0.19 kg,P2O5 0.05 kg,K2O 0.16 kg;土壤供养分量为N 104.55 kg/hm2,P2O5 30.15 kg/hm2,K2O 91.65 kg/hm2;土壤养分校正系数为N0.42,P2O5 0.07,K2O0.32;肥料利用率为N17.43%,P2O5 6.87%,K2O31.55%。[结论]得出的圆葱施肥模型和施肥参数对指导圆葱施肥具有重要的作用。     

信阳市“两优培特”杂交水稻钾肥施用量研究初报

通过固定 N、P肥适宜用量 ,设置钾肥不同施用量处理试验研究 ,结果表明 ,增施钾肥 ,能够显著增加“两优培特”杂交水稻的有效穗、每穗总粒数、实粒数。其中以处理 N12 P2 O56 K2 O9产投比最大 ,可作为信阳市水稻土上种植“两优培特”杂交水稻钾肥的最佳施用量     

涵江区花生“3414”田间肥效试验

通过开展花生＂3414＂田间肥效试验,建立氮、磷、钾肥施用量与花生产量的肥效模型,以确定最高施肥量和最佳施肥量,为当地花生配方施肥和推荐施肥提供理论依据。结果表明,在本试验条件下,花生每667 m2最高产量施肥量为N 7.58 kg,N∶P2O5∶K2O=1∶0.55∶1.12,花生最高产量369.34 kg;最佳经济施肥量为N 7.05 kg,N∶P2O5∶K2O=1∶0.56∶1.14,最佳利润达2 284.6元。     

Theoretical evidence for a c60 "window" mechanism

On the basis of semiempirical and high-level ab initio calculations, theoretical evidence is presented of a "window" mechanism operable on the surface of C(60) and other fullerenes. Through this mechanism, large holes may be formed in fullerenes excited to their triplet state, openings through which atoms and small molecules can pass. This work provides a theoretical foundation for experiments that have prepared endohedral noble gas compounds of C(60) under thermal excitation. A method is proposed that could increase the efficiency of the process of noble gas insertion into C(60) and provide a more general means to create endohedral fullerene compounds.     

The "spliceosome": yeast pre-messenger RNA associates with a 40S complex in a splicing-dependent reaction

The in vitro splicing reactions of pre-messenger RNA (pre-mRNA) in a yeast extract were analyzed by glycerol gradient centrifugation. Labeled pre-mRNA appears in a 40S peak only if the pre-mRNA undergoes the first of the two partial splicing reactions. RNA analysis after extraction of glycerol gradient fractions shows that lariat-form intermediates, molecules that occur only in mRNA splicing, are found almost exclusively in this 40S complex. Another reaction intermediate, cut 5' exon RNA, can also be found concentrated in this complex. The complex is stable even in 400 mM KCl, although at this salt concentration, it sediments at 35S and is clearly distinguishable from 40S ribosomal subunits. This complex, termed a "spliceosome," is thought to contain components necessary for mRNA splicing; its existence can explain how separated exons on pre-mRNA are brought into contact.