Keto-aldehydes and cell division   总被引：10，自引：0，他引：10  

A Szent-Gy?rgyi  L G Együd  J A McLaughlin 《Science (New York, N.Y.)》1967,155(762):539-541

Many problems are left open in this article. Its publication may be excused by the suffering cancer causes, which urges the researcher to publish as soon as he thinks he may have found a new trail, which also may be taken by others. What emerges clearly is that SH groups, with their specific reactivities, offer a hopeful target in the search for cancerostatic substances, among which the natural repressor of cell division may hold out the most promise. The glyoxal derivatives also have antiviral properties (7, 16) and may be in the center of a hitherto unknown system of equilibria which deserves a thorough study. The low molecular weight of the glyoxal derivative reported justifies the hope of an early clarification of its structure, as well as its synthesis (17).  相似文献   

共生性广谱生物固氮菌剂在红黄壤水稻上的应用效应研究     

程旺大  赵国平  姚海根 《上海交通大学学报(农业科学版)》2001,19(4):290-295

将共生性广谱生物固氮菌剂G肥应用于红黄壤水稻上,对水稻的一些生理活性、水稻的衰老、土壤肥力变化、稻米品质和产量进行了研究.结果表明,施用G肥能有效地促进水稻生长,稻株出叶速度加快,分蘖速度快,成穗率提高:叶片叶绿素含量提高,根系活力增强,尤其是在灌浆成熟期仍保持较高的叶绿素含量和根系活力,剑叶SOD、POD等保护酶类活性提高、MDA含量降低,对于提高光合速率、争取高产优质是极为有利的.结果还表明,施用G肥与常规栽培比,对稻米品质无明显影响.此外,施用G肥可减少氮肥20%,改善水稻经济性状,提高产量,直接经济效益明显:施用G肥可有效缓解偏施氮肥引起的土壤酸化,提高土壤全氮含量和有机质含量,对红黄壤的可持续开发利用具有重要的意义.  相似文献   

基于ResNet-50深度卷积网络的果树病害智能诊断模型研究   总被引：1，自引：1，他引：1  

金瑛  叶飒  李洪磊 《农业图书情报学刊》2021,(4):58-67

[目的/意义]果树病害危及农业生产安全,运用人工智能技术帮助果农及时准确地识别果树病害对保障农业安全生产具有重要意义。[方法/过程]采用10000张果树叶片病斑图像数据集,通过旋转、污化、增噪、切割等图像增强手段,提高样本图像的多样性;使用ResNet-50深度卷积网络模型,进行机器学习,获得果树病害识别模型,并基于此模型开发了应用软件提供在线诊断服务。[结果/结论]实验结果表明:该模型对4种果树病害的平均识别率达到92.9%,和相关研究成果相比具有较好的诊断效果。  相似文献   

Multiple glassy states in a simple model system     

Pham KN  Puertas AM  Bergenholtz J  Egelhaaf SU  Moussaïd A  Pusey PN  Schofield AB  Cates ME  Fuchs M  Poon WC 《Science (New York, N.Y.)》2002,296(5565):104-106

Experiments, theory, and simulation were used to study glass formation in a simple model system composed of hard spheres with short-range attraction ("sticky hard spheres"). The experiments, using well-characterized colloids, revealed a reentrant glass transition line. Mode-coupling theory calculations and molecular dynamics simulations suggest that the reentrance is due to the existence of two qualitatively different glassy states: one dominated by repulsion (with structural arrest due to caging) and the other by attraction (with structural arrest due to bonding). This picture is consistent with a study of the particle dynamics in the colloid using dynamic light scattering.  相似文献   

CoRoT measures solar-like oscillations and granulation in stars hotter than the Sun     

Michel E  Baglin A  Auvergne M  Catala C  Samadi R  Baudin F  Appourchaux T  Barban C  Weiss WW  Berthomieu G  Boumier P  Dupret MA  Garcia RA  Fridlund M  Garrido R  Goupil MJ  Kjeldsen H  Lebreton Y  Mosser B  Grotsch-Noels A  Janot-Pacheco E  Provost J  Roxburgh IW  Thoul A  Toutain T  Tiphène D  Turck-Chieze S  Vauclair SD  Vauclair GP  Aerts C  Alecian G  Ballot J  Charpinet S  Hubert AM  Lignières F  Mathias P  Monteiro MJ  Neiner C  Poretti E  de Medeiros JR  Ribas I  Rieutord ML  Cortés TR  Zwintz K 《Science (New York, N.Y.)》2008,322(5901):558-560

Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured oscillations and the stellar granulation signature in three main sequence stars that are noticeably hotter than the sun. The oscillation amplitudes are about 1.5 times as large as those in the Sun; the stellar granulation is up to three times as high. The stellar amplitudes are about 25% below the theoretic values, providing a measurement of the nonadiabaticity of the process ruling the oscillations in the outer layers of the stars.  相似文献   

Infectious behavior in a parasitoid     

Varaldi J  Fouillet P  Ravallec M  López-Ferber M  Boulétreau M  Fleury F 《Science (New York, N.Y.)》2003,302(5652):1930

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NSP1 of the GRAS protein family is essential for rhizobial Nod factor-induced transcription   总被引：1，自引：0，他引：1  

Smit P  Raedts J  Portyanko V  Debellé F  Gough C  Bisseling T  Geurts R 《Science (New York, N.Y.)》2005,308(5729):1789-1791

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A gain-of-function mutation in a cytokinin receptor triggers spontaneous root nodule organogenesis     

Tirichine L  Sandal N  Madsen LH  Radutoiu S  Albrektsen AS  Sato S  Asamizu E  Tabata S  Stougaard J 《Science (New York, N.Y.)》2007,315(5808):104-107

Legume root nodules originate from differentiated cortical cells that reenter the cell cycle and form organ primordia. We show that perception of the phytohormone cytokinin is a key element in this switch. Mutation of a Lotus japonicus cytokinin receptor gene leads to spontaneous development of root nodules in the absence of rhizobia or rhizobial signal molecules. The mutant histidine kinase receptor has cytokinin-independent activity and activates an Escherichia coli two-component phosphorelay system in vivo. Mutant analysis shows that cytokinin signaling is required for cell divisions that initiate nodule development and defines an autoregulated process where cytokinin induction of nodule stem cells is controlled by shoots.  相似文献   

浅谈温室油菜蚜虫危害     

萨如拉 《西藏农业科技》2007,29(3):14-18

油菜蚜虫是油菜上一种常发性的害虫,常年发生较重,油菜蚜虫对油菜的危害一是直接取食为害,二是传播病毒病,世代重叠危害,严重影响产量。本文论述了油菜蚜虫的生活习性、危害发生情况、控制虫害发生的原则、防治方法等。并提出了防止油菜蚜虫危害工作的建议。  相似文献   

A physical map of the 1-gigabase bread wheat chromosome 3B   总被引：2，自引：0，他引：2  

Paux E  Sourdille P  Salse J  Saintenac C  Choulet F  Leroy P  Korol A  Michalak M  Kianian S  Spielmeyer W  Lagudah E  Somers D  Kilian A  Alaux M  Vautrin S  Bergès H  Eversole K  Appels R  Safar J  Simkova H  Dolezel J  Bernard M  Feuillet C 《Science (New York, N.Y.)》2008,322(5898):101-104

As the staple food for 35% of the world's population, wheat is one of the most important crop species. To date, sequence-based tools to accelerate wheat improvement are lacking. As part of the international effort to sequence the 17-billion-base-pair hexaploid bread wheat genome (2n = 6x = 42 chromosomes), we constructed a bacterial artificial chromosome (BAC)-based integrated physical map of the largest chromosome, 3B, that alone is 995 megabases. A chromosome-specific BAC library was used to assemble 82% of the chromosome into 1036 contigs that were anchored with 1443 molecular markers, providing a major resource for genetic and genomic studies. This physical map establishes a template for the remaining wheat chromosomes and demonstrates the feasibility of constructing physical maps in large, complex, polyploid genomes with a chromosome-based approach.  相似文献