A thermally re-mendable cross-linked polymeric material     

Chen X  Dam MA  Ono K  Mal A  Shen H  Nutt SR  Sheran K  Wudl F 《Science (New York, N.Y.)》2002,295(5560):1698-1702

We have developed a transparent organic polymeric material that can repeatedly mend or "re-mend" itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120 degrees C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of "intermonomer" linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.  相似文献   

Amazon forests green-up during 2005 drought     

Saleska SR  Didan K  Huete AR  da Rocha HR 《Science (New York, N.Y.)》2007,318(5850):612

Coupled climate-carbon cycle models suggest that Amazon forests are vulnerable to both long- and short-term droughts, but satellite observations showed a large-scale photosynthetic green-up in intact evergreen forests of the Amazon in response to a short, intense drought in 2005. These findings suggest that Amazon forests, although threatened by human-caused deforestation and fire and possibly by more severe long-term droughts, may be more resilient to climate changes than ecosystem models assume.  相似文献   

Dependence of EPSP efficacy on synapse location in neocortical pyramidal neurons     

Williams SR  Stuart GJ 《Science (New York, N.Y.)》2002,295(5561):1907-1910

Neurons receive thousands of synaptic inputs throughout elaborate dendritic trees. Here we determine the somatic impact of excitatory postsynaptic potentials (EPSPs) generated at known dendritic sites in neocortical pyramidal neurons. As inputs became more distal, somatic EPSP amplitude decreased, whereas use-dependent depression increased. Despite marked attenuation (>40-fold), when coactivated within a narrow time window (approximately 10 milliseconds), distal EPSPs could directly influence action potential output following dendritic spike generation. These findings reveal that distal EPSPs are ineffective sources of background somatic excitation, but through coincidence detection have a powerful transient signaling role.  相似文献   

Regulation of chromatin remodeling by inositol polyphosphates     

Steger DJ  Haswell ES  Miller AL  Wente SR  O'Shea EK 《Science (New York, N.Y.)》2003,299(5603):114-116

  相似文献   

Convergent domestication of cereal crops by independent mutations at corresponding genetic Loci   总被引：1，自引：0，他引：1  

Paterson AH  Lin YR  Li Z  Schertz KF  Doebley JF  Pinson SR  Liu SC  Stansel JW  Irvine JE 《Science (New York, N.Y.)》1995,269(5231):1714-1718

Independent domestication of sorghum, rice, and maize involved convergent selection for large seeds, reduced disarticulation of the mature inflorescence, and daylength-insensitive flowering. These similar phenotypes are largely determined by a small number of quantitative trait loci (QTLs) that correspond closely in the three taxa. The correspondence of these QTLs transcends 65 million years of reproductive isolation. This finding supports models of quantitative inheritance that invoke relatively few genes, obviates difficulties in map-based cloning of QTLs, and impels the comparative mapping of complex pheno-types across large evolutionary distances, such as those that separate humans from rodents and domesticated mammals.  相似文献   

Response     

Hart SR  Hauri EH  Oschmann LA  Whitehead JA 《Science (New York, N.Y.)》1992,258(5083):821-822

  相似文献   

Identification of the so-called "lard factor" as vitamin A     

AMES SR  HARRIS PL 《Science (New York, N.Y.)》1954,120(3114):391-393

  相似文献   

THE PRODUCTION AND UTILIZATION OF ALCOHOL BY PLANT TISSUES     

Ludwig CA  Allison FE  Hoover SR  Minor FW 《Science (New York, N.Y.)》1940,91(2355):170-171

  相似文献   

Human chromosome 7: DNA sequence and biology     

Scherer SW  Cheung J  MacDonald JR  Osborne LR  Nakabayashi K  Herbrick JA  Carson AR  Parker-Katiraee L  Skaug J  Khaja R  Zhang J  Hudek AK  Li M  Haddad M  Duggan GE  Fernandez BA  Kanematsu E  Gentles S  Christopoulos CC  Choufani S  Kwasnicka D  Zheng XH  Lai Z  Nusskern D  Zhang Q  Gu Z  Lu F  Zeesman S  Nowaczyk MJ  Teshima I  Chitayat D  Shuman C  Weksberg R  Zackai EH  Grebe TA  Cox SR  Kirkpatrick SJ  Rahman N  Friedman JM  Heng HH  Pelicci PG  Lo-Coco F  Belloni E  Shaffer LG  Pober B  Morton CC  Gusella JF  Bruns GA  Korf BR 《Science (New York, N.Y.)》2003,300(5620):767-772

  相似文献   

Conservation and rewiring of functional modules revealed by an epistasis map in fission yeast     

Roguev A  Bandyopadhyay S  Zofall M  Zhang K  Fischer T  Collins SR  Qu H  Shales M  Park HO  Hayles J  Hoe KL  Kim DU  Ideker T  Grewal SI  Weissman JS  Krogan NJ 《Science (New York, N.Y.)》2008,322(5900):405-410

  相似文献