A Handbook of Industrial Districts – Edited by Giacomo Becattini,Marco Bellandi,and Lisa De Propris     

Simon Stephens 《Growth and change》2011,42(3):426-428

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Contaminated evidence     

Loftus EF  Cole SA 《Science (New York, N.Y.)》2004,304(5673):959

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Small interfering RNA-induced transcriptional gene silencing in human cells   总被引：1，自引：0，他引：1  

Morris KV  Chan SW  Jacobsen SE  Looney DJ 《Science (New York, N.Y.)》2004,305(5688):1289-1292

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The formation and fragmentation of disks around primordial protostars     

Clark PC  Glover SC  Smith RJ  Greif TH  Klessen RS  Bromm V 《Science (New York, N.Y.)》2011,331(6020):1040-1042

The very first stars to form in the universe heralded an end to the cosmic dark ages and introduced new physical processes that shaped early cosmic evolution. Until now, it was thought that these stars lived short, solitary lives, with only one extremely massive star, or possibly a very wide binary system, forming in each dark-matter minihalo. Here we describe numerical simulations that show that these stars were, to the contrary, often members of tight multiple systems. Our results show that the disks that formed around the first young stars were unstable to gravitational fragmentation, possibly producing small binary and higher-order systems that had separations as small as the distance between Earth and the Sun.  相似文献   

Cancer. New epigenetic drivers of cancers     

Elsässer SJ  Allis CD  Lewis PW 《Science (New York, N.Y.)》2011,331(6021):1145-1146

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An ion balance for ultra-high-precision atomic mass measurements     

Rainville S  Thompson JK  Pritchard DE 《Science (New York, N.Y.)》2004,303(5656):334-338

We have developed the analog of a double-pan balance for determining the masses of single molecular ions from the ratio of their two cyclotron frequencies. By confining two different ions on the same magnetron orbit in a Penning trap, we balance out many sources of noise and error (such as fluctuations of the magnetic field). To minimize the systematic error associated with the Coulomb interaction between the two ions, they are kept about 1 millimeter apart from each other, resulting in fractional uncertainty below 1 x 10(-11). Such precision opens the door to numerous applications of mass spectrometry, including metrology, fundamental physics, and weighing chemical bonds.  相似文献   

Sulfur diagenesis in everglades peat and origin of pyrite in coal     

Altschuler ZS  Schnepfe MM  Silber CC  Simon FO 《Science (New York, N.Y.)》1983,221(4607):221-227

The pattern of sulfur transformation in peat across the Everglades basin indicates that pyrite formation in organic-rich swamps depends on the use of organic oxysulfur compounds in dissimilatory respiration by sulfur-reducing bacteria. This paragenesis explains the primary distribution of sulfur compounds in low-sulfur coals and possibly in most coals and many organic-rich soils and sediments. It also accounts for the occurrence of framboidal pyrite bound in fossil tissue in coal and sediments.  相似文献   

Hematopoietic cell regulation by Rac1 and Rac2 guanosine triphosphatases     

Gu Y  Filippi MD  Cancelas JA  Siefring JE  Williams EP  Jasti AC  Harris CE  Lee AW  Prabhakar R  Atkinson SJ  Kwiatkowski DJ  Williams DA 《Science (New York, N.Y.)》2003,302(5644):445-449

The Rho guanosine triphosphatases (GTPases) Rac1 and Rac2 are critical signaling regulators in mammalian cells. The deletion of both Rac1 and Rac2 murine alleles leads to a massive egress of hematopoietic stem/progenitor cells (HSC/Ps) into the blood from the marrow, whereas Rac1-/- but not Rac2-/- HSC/Ps fail to engraft in the bone marrow of irradiated recipient mice. In contrast, Rac2, but not Rac1, regulates superoxide production and directed migration in neutrophils, and in each cell type, the two GTPases play distinct roles in actin organization, cell survival, and proliferation. Thus, Rac1 and Rac2 regulate unique aspects of hematopoietic development and function.  相似文献   

PKA type IIalpha holoenzyme reveals a combinatorial strategy for isoform diversity     

Wu J  Brown SH  von Daake S  Taylor SS 《Science (New York, N.Y.)》2007,318(5848):274-279

The catalytic (C) subunit of cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) is inhibited by two classes of regulatory subunits, RI and RII. The RII subunits are substrates as well as inhibitors and do not require adenosine triphosphate (ATP) to form holoenzyme, which distinguishes them from RI subunits. To understand the molecular basis for isoform diversity, we solved the crystal structure of an RIIalpha holoenzyme and compared it to the RIalpha holoenzyme. Unphosphorylated RIIalpha(90-400), a deletion mutant, undergoes major conformational changes as both of the cAMP-binding domains wrap around the C subunit's large lobe. The hallmark of this conformational reorganization is the helix switch in domain A. The C subunit is in an open conformation, and its carboxyl-terminal tail is disordered. This structure demonstrates the conserved and isoform-specific features of RI and RII and the importance of ATP, and also provides a new paradigm for designing isoform-specific activators or antagonists for PKA.  相似文献   

Poliovirus crystals within the endoplasmic reticulum of endothelial and mononuclear cells in the monkey spinal cord   总被引：9，自引：0，他引：9  

K Blinzinger  J Simon  D Magrath  L Boulger 《Science (New York, N.Y.)》1969,163(873):1336-1337

The lumbar motor columns of a cynomolgus monkey that had become tetraplegic after experimental infection with a highly virulent strain of type 3 poliovirus were examined by electron microscopy. Crystalline aggregates of poliovirus occurred within the endoplasmic reticulum of endothelial cells as well as of mononuclear inflammatory cells. This finding suggests that the endoplasmic reticulum might be much more involved in poliovirus multiplication than has been previously supposed.  相似文献