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991.
Fifty patients with back pain and radiologically diagnosed spondylolysis were evaluated by a single-photon emission computed tomography (SPECT bone scanning). These patients were separated into three groups according to the degree of spondylolisthesis accompanying the spondylolysis. The data obtained from the study indicate that in acute spondylolysis, the SPECT scan is positive at the pars interarticularis. As the spondylolysis becomes chronic, the SPECT scan tends to revert toward normal even though healing of the spondylolysis has not occurred. As spondylolisthesis develops and progresses, the SPECT scan again becomes positive. The positivity, however, is more anterior and more diffuse. The authors propose that SPECT scanning in spondylolysis is not a positive or negative process, but rather varies with the time and stability of the spondylolytic spine.  相似文献   
992.
993.
Five new eunicellin-type diterpenoids, briarellins E--I, along with several known diterpenoids of the asbestinane, briarane and eunicellane classes, were isolated from the Caribbean gorgonian octocoral Briareum asbestinum collected in Puerto Rico. The structures of these compounds were established on the basis of spectroscopic evidence.  相似文献   
994.
A population of catalytic RNA molecules has been engineered to operate and evolve in vitro in a continuous manner. The novel continuity of the process allows the propagation of many generations in a very short time and without the manual manipulation necessary with traditional in vitro selection techniques.  相似文献   
995.
996.
997.
In a 2 month-old infant presenting with the symptoms of cardio-respiratory failure in the course of staphylococcal septicaemia a thrombus in the right ventricle was detected in an echocardiographic examination. Scintigraphy of the lungs revealed of microthrombosis. Thrombolytic therapy with recombinant tissue plasminogen activator (Actylise) was started on the dose of 0.5 mg/kg/hour in 7-hour constant infusion. After 5 days of treatment the thrombus was completely dissolved. No complication were observed. Indicators of serum clothing remained normal during the treatment.  相似文献   
998.
AD Michaels 《Canadian Metallurgical Quarterly》1997,336(26):1916; author reply 1916-1916; author reply 1917
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999.
1000.
Spores of a known toxigenic and psychrotrophic dairy isolate of Bacillus cereus (HRM 44) were unable to grow and produce diarrhoeagenic toxin at 6 degrees C in creams and dairy-based products. These findings suggest that the production of B. cereus diarrhoeagenic toxin is unlikely to occur in creams and dairy-based products maintained within the cold chain. Growth and toxin production were readily demonstrated in creams and some desserts stored at 21 degrees C. Growth in creams was associated with obvious spoilage. However, in the flavoured desserts, spoilage was not always obvious before significant growth of B. cereus and toxin production had occurred. Dairy desserts with high sugar content and/or low pH did not support toxin production and these findings are discussed.  相似文献   
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