基于"尚义大桃"和"红木"资源利用的胡麻骨干亲本选择重要性评价

详细收集和分析了20世纪70、80～90年代育成的一些骨干品种资料,发现这些品种有一个共同特点,即亲本之一大多来自同一资源,如70年代农家品种资源＂尚义大桃＂和80～90年代国外抗病资源＂红木＂是利用频率最高的亲本,而且成效最大。可以看出,一个优异的胡麻品种资源对新品种选育具有重要作用,加强胡麻品种资源研究和创新是目前和将来育种工作的一项长期重要的任务。     

Singlet diradicals: from transition states to crystalline compounds

Singlet diradicals are usually not energy minima. As observed by femtosecond spectroscopy, they readily couple to form final sigma bonds. Substituent effects allow lifetimes to increase into the microsecond range. Taking advantage of the properties of hetero-elements, a diradical has been prepared that is indefinitely stable at room temperature. The availability of diradicals that can be handled under standard laboratory conditions will lead to further insight into their chemical and physical properties, raising the likelihood of practical applications, especially in the field of molecular materials such as electrical conductors and ferromagnets.     

Synthesis of Linear Acetylenic Carbon: The "sp" Carbon Allotrope

A carbon allotrope based on "sp" hybridization containing alternating triple and single bonds (an acetylenic or linear carbon allotrope) has been prepared. Studies of small (8 to 28 carbon atoms) acetylenic carbon model compounds show that such species are quite stable (130 degrees to 140 degrees C) provided that nonreactive terminal groups or end caps (such as tert-butyl or trifluoromethyl) are present to stabilize these molecules against further reactions. In the presence of end capping groups, laser-based synthetic techniques similar to those normally used to generate fullerenes, produce thermally stable acetylenic carbon species capped with trifluoromethyl or nitrile groups with chain lengths in excess of 300 carbon atoms. Under these conditions, only a negligible quantity of fullerenes is produced. Acetylenic carbon compounds are not particularly moisture or oxygen sensitive but are moderately light sensitive.     

Analysis of phenotype array data from Biolog MicroPlatesTM

Biolog MicroPlates TM. are employed to characterize Trichoderma isolates based on differential assimilation of test substrates and redox reactions in a 96-well test plate. The Biolog method is potentially advantageous in being relatively simple, fast and economical, and data acquisition can be automated using a microplate reader and applicable software. Several research applications of the Biolog system are presented: i) “monophenetic groups” from cluster analyses of phenotype array da…     

Significance of "tethyan" fossils in the american cordillera

Equatorial faunas of the ancient Tethyan seaway, which extended from western Europe to southeastern Asia, comprise some of the most diverse marine taxa in the fossil record. Comparable or identical "Tethyan" species that occur far from the Tethyan seaway in Paleozoic and Mesozoic rocks of the North and South American Cordillera have long been considered as a major biogeographic anomaly. Two leading theories to account for the occurrence of these anomalous "Tethyan" faunas in the Cordillera are that they were transported long distances to the east on tectonic blocks(suspect terranes that originated near the Tethys) or that they migrated westward via undiscovered marine corridors through continental areas of Pangea. An alternative model is that these "Tethyan" fauna were pantropic species that extended with attenuated diversities into the eastern proto-Pacific Ocean. This pantropic model can better account for the distribution patterns of many Paleozoic and early Mesozoic "Tethyan" species in the American Cordillera and provides a steady state hypothesis against which the other models can be tested. The distribution of pre-Cretaceous "Tethyan" faunas is similar to the known pantropic distribution of many Cretaceous and Cenozoic tropical biotas. During the Cenozoic, taxa were most diverse in the Tethys and Indo-West Pacific regions but extended with attenuated diversity to many parts of the equatorial Pacific Ocean, including the west coasts of North and South America. The eastern Pacific occurrence of many Indo-West Pacific species provides a modern analog for the occurrence of many anomalous "Tethyan" fossils in the American Cordillera.     

Amphibians as indicators of early tertiary "out-of-India" dispersal of vertebrates

Sixty-five million years ago, massive volcanism produced on the India-Seychelles landmass the largest continental lava deposit (Deccan Traps) of the past 200 million years. Using a molecular clock-independent approach for inferring dating information from molecular phylogenies, we show that multiple lineages of frogs survived Deccan Traps volcanism after millions of years of isolation on drifting India. The collision between the Indian and Eurasian plates was followed by wide dispersal of several of these lineages. This "out-of-India" scenario reveals a zoogeographical pattern that might reconcile paleontological and molecular data in other vertebrate groups.     

"Molecule corrals" for studies of monolayer organic films

Scanning tunneling microscopy (STM) studies have demonstrated that monolayer-deep, flat-bottomed, circular etch pits can be grown on highly ordered pyrolytic graphite by high-temperature etching in the presence of oxygen. In this work, these graphite etch pits are used as "molecule corrals" to isolate ensembles of molecules for study by STM. The nucleation of self-assembled molecular films in the corrals took place by nucleation events separate from those leading to self-assembly on the surrounding terrace and allowed the measurement of the nucleation rate constant in the corrals. The dependence of the nucleation rate for self-assembly on pit size shows that nucleation occurs at open terrace sites and that step edges (that is, the corral's perimeter) and confinement inhibit film growth.     

Direct observation of chemical bond dynamics on surfaces

The dynamics of chemisorbed species as they swing to-and-fro on their adsorption sites may be directly observed with electron-stimulated desorption. The observation of the thermal disorder in adsorbate chemical bond directions, through studies of the thermal excitation of librational modes, allows one to visualize the potential energy surfaces controlling the structure and dynamics of adsorbates on single crystal metal and semiconductor surfaces. This information may be useful in understanding surface diffusion as well as the spatial aspects of surface chemical reactions.     

"Frozen" transition States: pentavalent carbon et Al

Organic ligands have been designed for the stabilization of specific geometries of compounds of nonmetallic elements. These ligands have made possible the isolation, or direct observation, of large numbers of trigonal bipyramidal organo-nonmetallic species. Many of these species are analogs of transition states for nucleophilic displacement reactions and have been stabilized by the ligands to such a degree that they have become ground-state energy minima. Ideas derived from research on these species have been applied to carbon species to generate a molecule that is an analog of the transition state for the associative nucleophilic displacement reaction. The molecule is a pentavalent carbon species that has been observed by nuclear magnetic resonance spectroscopy.     

The rotational spectrum and structure of the HOOO radical

The adduct of the hydroxyl radical with oxygen has been studied theoretically, in connection with atmospheric reactions, but its stability and structure remained an open question. Pure rotational spectra of the HOOO and DOOO radicals have now been observed in a supersonic jet by using a Fourier-transform microwave spectrometer with a pulsed discharge nozzle. The molecular constants extracted from 12 rotational transitions with fine and hyperfine splittings support a trans planar molecular structure, in contrast to the cis planar structure predicted by most ab initio calculations. The bond linking the HO and O2 moieties is fairly long (1.688 angstroms) and comparable to the F-O bond in the isoelectronic FOO radical.     

PCR analysis of different ladybird species (<Emphasis Type="Italic">Coleoptera</Emphasis>, Coccinellidae) with universal RAPD primers

Universal RAPD primers (OPA02 and OPA07) have been revealed for ladybird beetles of the Coccinellidae family. Using these primers, comparative PCR analysis of ten different ladybird beetle species was conducted. It was shown that Harmonia axyridis beetle species had the highest level of DNA polymorphism and genetic diversity. The RAPD-PCR method for analysis of interspecies differences along with other molecular genetics methods can be used.     

Directional dynamics in the photodissociation of oriented molecules

We observed directional dynamics in the photodissociation of an oriented molecule. When a laser dissociated hexapole-oriented carbonyl sulfide molecules, the three-dimensional recoil of carbon monoxide fragments, which we measured with ion imaging, was strongly asymmetric. We obtained a microscopic view of molecular bond breaking that revealed both the sign and the magnitude of the deflection angle of the fragment in the molecular frame. This experimental approach can be applied to study and control the three-dimensional dynamics of photoinitiated reactions of fixed molecules or molecules oriented by emerging techniques.     

Formation of catalytic metal-molecule contacts

We describe a new strategy for the in situ growth of molecular wires predicated on the synthesis of a trifunctional "primed" contact formed from metal-carbon multiple bonds. The ruthenium-carbon pi bond provides structural stability to the molecular linkages under ambient conditions, and density functional calculations indicate the formation of an efficient conduit for charge carriers to pass between the metal and the molecule. Moreover, the metal-carbon pi bond provides a chemically reactive site from which a conjugated molecular wire can be grown in situ through an olefin metathesis reaction.     

Autoionization in liquid water

The dissociation of a water molecule in liquid water is the fundamental event in acid-base chemistry, determining the pH of water. Because of the short time scales and microscopic length scales involved, the dynamics of this autoionization have not been directly probed by experiment. Here, the autoionization mechanism is revealed by sampling and analyzing ab initio molecular dynamics trajectories. We identify the rare fluctuations in solvation energies that destabilize an oxygen-hydrogen bond. Through the transfer of protons along a hydrogen bond "wire," the nascent ions separate by three or more neighbors. If the hydrogen bond wire connecting the two ions is subsequently broken, a metastable charge-separated state is visited. The ions may then diffuse to large separations. If, however, the hydrogen bond wire remains unbroken, the ions recombine rapidly. Because of their concomitant large electric fields, the transient ionic species produced in this case may provide an experimentally detectable signal of the dynamics we report.     

Nature of "sex-ratio" agent in Drosophila

Several lines of evidence implicate small spirochetes, presumably treponemata, as etiologic agents in the production of the maternally transmitted "sex ratio" condition (SR) in Drosophila nebulosa, in D. willistoni, and in strains of D. melanogaster into which the SR condition has been artificially transferred. The presence of treponemata in the hemolymph of adult females of these species is completely correlated with the production of unisexual progenies and like this condition is dependent on the genotype of the host and of the infectious agent.     

肉用畜禽肌纤维发育特性

为了解肉用畜禽(牛、绵羊、猪和家禽等)肌纤维发育特性的最新研究现状,以"畜禽"、"肌纤维发育"和"肉品质"为关键词,对1981—2019年国内外相关研究进行了检索,分别从肌纤维特性、肌纤维生成过程、肌纤维生长发育的分子调控等方面归纳了不同畜禽的肌纤维发育特征。研究发现:不同畜禽肌纤维发育的一般过程基本相似;肌纤维发育的时间具有物种特异性;个别基因被确定具有调控肌纤维发育的主要功能;仍缺乏多物种肌纤维发育过程基因调控网络的构建与系统比较研究以及多物种肉品质鉴定的通用分子标记开发。     

Laser femtochemistry

Femtochemistry is concerned with the very act of the molecular motion that brings about chemistry, chemical bond breaking, or bond formation on the femtosecond (10(-15) second) time scale. With lasers it is now possible to record snapshots of chemical reactions with sub-angstrom resolution. This strobing of the transition-state region between reagents and products provides real time observations that are fundamental to understanding the dynamics of the chemical bond.     

Controlled acceleration and inhibition of bergman cyclization by metal chlorides

The Bergman cyclization has been the subject of renewed interest with the discovery of naturally occurring enediyne-based antitumor agents that cleave DNA by means of an aromatic diradical. These natural substrates have a means to trigger this cycloaromatization process. Control of this reaction by substrate modification would allow aromatic diradicals to be generated selectively. In the studies presented here it is disclosed that the Bergman cyclization of 1,2-bis(diphenyl phosphinoethynyl) benzene was accelerated by a factor of >30,000 by the addition of palladium(II) chloride or platinum(II) chloride and was inhibited by the addition of mercury(II) chloride.     

棉花“洞A”型核雄性不育形态及机理研究现状

综述了现阶段棉花"洞A"型核雄性不育系花粉败育的研究概况,从形态学、细胞形态学、生理生化及分子生物学等方面总结了研究棉花"洞A"型核雄性不育败育机理的进展,并且对该领域研究和应用中存在的问题、发展前景提出了一些看法。     

抗白色念球菌的复方"克清甲"软膏毒性研究

[目的]考察抗白色念球菌的复方＂克清甲＂软膏经皮给药及入眼对试验动物的安全性。[方法]采用健康家兔进行皮肤急性毒性试验、皮肤及眼刺激试验,用健康豚鼠进行主动皮肤过敏试验,并观察。[结果]复方＂克清甲＂软膏未产生急性毒性反应和眼刺激反应;对于家兔完整皮肤,单次和多次经皮给药均无刺激性,对破损皮肤有轻度刺激反应,但除去药物后这种刺激性消失;对健康豚鼠完整及破损皮肤均无致敏性。[结论]复方＂克清甲＂软膏是一种安全的外用制剂。