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101.
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The 351-nanometer photoelectron spectrum of the planar cyclooctatetraene radical anion (COT·-) shows transitions to two electronic states of cyclooctatetraene (COT). These states correspond to the D4h 1A1g state, which is the transition state for COT ring inversion, and the D8h 3A2u state. The electron binding energy of the 1A1g transition state is 1.099 ± 0.010 electron volts, which is lower by 12.1 ± 0.3 kilocalories per mole than that of the 3A2u state. The photoelectron spectrum shows that the singlet lies well below the triplet in D8h COT and confirms ab initio predictions that the molecule violates Hund's rule. Vibrational structure is observed for both features and is readily assigned by use of a simple potential energy surface. 相似文献
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Evidence of in situ metal (iron and manganese) deposition onto bacteria associated with rapidly sinking particles in the open ocean is reported. Below 100 meters, bacteria are found with extracellular capsules containing metal precipitates; the frequency of these capsules increases with depth. The capsular metal deposits appear to contribute a major portion of the weakly bound fraction of the particulate iron flux. 相似文献
105.
Although it is commonly assumed that subduction has operated continuously on Earth without interruption, subduction zones are routinely terminated by ocean closure and supercontinent assembly. Under certain circumstances, this could lead to a dramatic loss of subduction, globally. Closure of a Pacific-type basin, for example, would eliminate most subduction, unless this loss were compensated for by comparable subduction initiation elsewhere. Given the evidence for Pacific-type closure in Earth's past, the absence of a direct mechanism for termination/initiation compensation, and recent data supporting a minimum in subduction flux in the Mesoproterozoic, we hypothesize that dramatic reductions or temporary cessations of subduction have occurred in Earth's history. Such deviations in the continuity of plate tectonics have important consequences for Earth's thermal and continental evolution. 相似文献
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DR THOMPSON D. RUGG PG SCOTT LG CRAMER† RA BARRICK† 《Australian veterinary journal》1994,71(6):161-164
SUMMARY An ivermectin-based jetting fluid was assessed for its efficacy in the prevention of blowfly strike and treatment of lice in long-wooled sheep. The ivermectin concentrate was diluted to 0.03 mg/mL and applied via a standard hand jetting technique. In insectary studies, using laboratory-reared Lucilia cuprina, sheep jetted with ivermectin were protected from induced breech and body strikes for 18 weeks after treatment. Merino and Corriedale sheep were equally protected, as were sheep subjected to 25 mm simulated rainfall at 1, 3 or 6 hours after jetting. Naturally occurring infestations of lice, Bovicola (Damalinia) ovis, were successfully treated with ivermectin jetting fluid in Merino and Corriedale sheep using a standard hand jetting technique. In addition, the efficacy of treatment was not affected by simulated rainfall at 1, 3 or 6 hours after treatment. 相似文献
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Gena M. Silver DVM MS Rodney S. Bagley DVM Patrick R. Gavin DVM PhD Hege Kippenes DVM 《Veterinary radiology & ultrasound》2001,42(3):231-234
A 6 month-old dog was examined for progressive paraparesis. On physical examination bony malformations were palpated over the cranial lumbar vertebral bodies and on the left metatarsal bone. Neuroanatomic lesion localization for the paraparesis was a T3-L3 spinal cord lesion. Radiographs confirmed bony masses at L1-L2 and on the left 3rd metatarsal bone. Magnetic resonance imaging was performed from T3-L3. Severe spinal cord compression was identified at L1-L2. Surgical decompression and biopsy confirmed the mass to be cartilaginous exostoses. This paper is an example of cartilaginous exostoses imaged with MR. 相似文献
110.