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Sutherland RD 《Cardiovascular diseases》1979,6(1):59-60
This report involves the surgical treatment of a patient who underwent saphenous vein triple coronary artery bypass and subsequently developed an ascending aortic aneurysm and aortic insufficiency. Although the implantation of vascular structures into synthetic grafts is commonplace, this case is unique in that it involves the successful implantation of an aortic island containing the origin of the coronary arteries. 相似文献
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Myocardial infarction is a rare complication of maximal exercise testing.(1) In the case presented here, infarction occurred in a 54-year-old man, 14 minutes after he showed a normal response to maximal multistage treadmill exercise testing. The presence of coronary artery disease had been documented angiographically prior to exercise testing. After infarction, the patient underwent emergency double aortocoronary bypass to the left anterior descending and right coronary arteries with good results. Clinical evidence suggests that the extent of myocardial necrosis was reduced by timely surgical intervention. There is no conclusive explanation for this patient's normal response to maximal exercise testing in the presence of advanced coronary artery occlusive disease followed rapidly by infarction. The value of exercise testing is well established in assessing the existence or severity of coronary artery disease; a normal response, however, cannot be used as an infallible indication that critical coronary artery disease does not exist. 相似文献
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河北阳原—蔚县晚上新世小哺乳动物化石 总被引:16,自引:10,他引:6
1984年于泥河湾组下段下部发现小哺乳动物化石标本1800余件,经初步鉴定,它们代表了食虫目、啮齿目和兔形目的26个种,其中的 Paenelimnoecus, Pliopentalagus, Germanomys 为我国首次发现.估计动物群的时代为游河期早期,相当于欧洲的维拉方早期 (MN 16). 相似文献
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自Ege等(1974)4的工作开始,在70年代已逐步建立起一种通过微细胞把一个细胞的染色体转移到另一个细胞中,并作为在杂种细胞里起作用的遗传因素,永远地保留下去的技术。
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富营养化导致的湖泊、水库蓝藻水华带来了一系列环境和生态问题。微囊藻群体形成,在水体表面的聚集是形成水华的重要策略之一。微囊藻群体形成有效抵御了草食性动物摄食、病毒、细菌的侵害,耐受不良环境因子(紫外辐射、高光强、重金属等)能力显著增强。文章探讨了野外微囊藻群体占优势的机制并综述了影响微囊藻群体形成的外源因子及作用机理,包括非生物因子(营养、温度、光照、重金属、微囊藻毒素、乙醛酸)、生物因子(草食性动物、细菌、鱼类、藻类)。基于现有研究,本综述还对未来研究进行展望:(1)非生物因子与生物因子协同效应对藻类形态影响研究; (2)人类活动对浮游藻类形态及动态的影响研究;(3)藻类形态对沉水植物的响应在未来淡水生态系统修复中的应用; (4)促进藻类群体形成的胞外多糖分泌在未来工业生产中的作用。 相似文献
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最近五年(1980-1984)来。我们在湖北省西部和江西省南部的14个县、市,包括神农架林区,采集了若干轮藻标本。经过鉴定,得到此科植物二属、六种和二变种。这是此两个地区轮藻科植物的首次报告。 相似文献
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James W. Wallace 《American journal of botany》1979,66(3):343-346
C-Glycosylflavones appear to be the only detectable flavonoids in representative species of Gnetum, Ephedra and Welwitschia. Ephedra antisyphilitica contains mixed 6,8-di-C-glycosides of apigenin and luteolin and Welwitschia mirabilis produces 6-C-glycosylchrysoeriol and 6,8-di-C-glycosylchrysoeriol. Recently it was reported that Gnetum gnemon contains 6-C-, 8-C and 6,8-di-C-glucosyl derivatives of apigenin, luteolin and their 7-0-methyl ethers. Based on the present preliminary survey the apparent absence of other flavonoid types indicates that C-glycosylflavones may be a unifying characteristic of the Gnetopsida. 相似文献
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FACTORS INFLUENCING BRAIN AND TISSUE LEVELS OF TRYPTAMINE: SPECIES, DRUGS AND LESIONS 总被引:1,自引:1,他引:0
J. W. Sloan W. R. Martin T. H. Clements W. F. Buchwald S. R. Bridges 《Journal of neurochemistry》1975,24(3):523-532
With a modification of the spectrophotofluorometric (SPF) method of HESS & UDENFRIEND (1959) (J. Pharmac. exp. Ther. 127 , 175-177), brain tryptamine levels in the rat (20.9 ng/g) and guinea-pig (20.7 ng/g) were found to be less than those in the dog (32.1 ng/g) and cat (52.2 ng/g). Regional distribution studies in the dog and cat showed that tryptamine was present in all major brain regions with highest concentrations in the spinal cord. Blood levels of tryptamine in the guinea-pig, dog and cat (6-7 ng/ml) were lower than brain levels. Pargyline significantly increased brain tryptamine in both the dog and cat; whereas, isocarboxazid (after 4 h) increased brain tryptamine levels in the dog but decreased brain levels in the cat. Reserpine (0.5-1.0 mg/kg per day for 1-4 days) did not significantly decrease brain, spinal cord or blood tryptamine levels in the dog. Spinal cord transection did not decrease tryptamine levels below the lesion in the chronic spinal dog. 相似文献
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Cleveland JC 《Cardiovascular diseases》1979,6(2):191-194
This case report describes a useful and unusual route for insertion of an intraaortic balloon in 63-year-old man who was operated upon for calcific aortic stenosis, coronary atherosclerosis involving the left anterior descending and right coronary arteries, and a large abdominal aortic aneurysm. Aortic valve replacement was accomplished with a porcine heterograft prosthesis. Bypasses to the left anterior descending and right coronary arteries were constructed with reversed saphenous vein grafts, and the abdominal aneurysm was resected and repaired with a bifurcated woven Dacron vascular graft. An electively placed intraaortic balloon was inserted through the right limb of the aortic graft prosthesis and used to assist the patient during the immediate postoperative period. Uneventful recovery ensued. 相似文献
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细根周转要消耗大量的C,它影响森林生态系统C分配格局与过程和养分循环,对生态系统生产力具有重要意义。细根的周转取决于细根的寿命,细根寿命越短,周转越快,根系对C的消耗也越多。大量研究表明,细根的寿命与地上部分C向根系供应的多少有密切关系,同时也与细根直径大小、土壤中N和水分的有效性、土壤温度以及根际周围的土壤动物和微生物的活动有关。本文综述了国外近年来在该领域里的研究进展,特别是对控制细根寿命的机理和主要影响因子进行了评述,目的是引起国内研究者的关注,促进我国根系生态学的研究与发展。 相似文献
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Houchin D 《Cardiovascular diseases》1978,5(4):347-353
A 49-year-old patient with known tetralogy of Fallot for which an aortopulmonary anastomosis (Pott's shunt) had been performed 23 years previously, underwent simultaneous myocardial revascularization for severe coronary occlusive disease and total correction of his congenital anomaly. The operation and postoperative course were uneventful, and he made a full recovery. 相似文献
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在云南西双版纳州勐腊自然保护区补蚌村的灰阴河望天树(Shorea wantianshuea)林, 选择群落结构均一的100 m×200 m区域,设置3条垂直于 沟谷并沿谷底到坡顶纵向延伸的20 m×100 m样带 (间隔50 m),在每一样带内每隔20 m设置谷底、低坡、中坡、次坡顶和坡顶5个均匀分布的 观测样地,每一样地内设置两个3 m×3 m的小样方。从2004年12月初到2005年9月底每隔2 ~3个月重复记录幼苗株高、基径和叶片数,统计幼 苗死亡数和被动物捕食数,计算幼苗死亡率、动物捕食率和存活率;同时测定各样地土壤含水量。实验结束收获全部现存幼苗,测定和计算幼 苗单株叶面积、比叶面积、总生物量和根冠比等生长参数。结果表明:在干旱季节,从谷底到坡顶,各样地土壤含水量依次降低,而幼苗死亡 率则依次增大,这种趋势一直持续到实验结束,此时幼苗在谷底、低坡、中坡、次坡顶和坡顶的死亡率分别为55.0%、54. 3%、39.4%、35.9%和 26.5%。动物捕食导致望天树幼苗的大量损失,但各样地间差异不显著,幼苗的“丢失”也可能是动物捕食的结果。水分胁迫对幼苗生长的影响 在干旱季节更为明显,实验结束时幼苗株高在谷底和低坡较大,而在坡顶和次坡顶较小,其它生长参数也都表现出类似的特点,但在实验结束 时这些差异并不显著。该文就各种环境因素对望天树幼苗生长与存活的影响进行了讨论。研究的结果可为探寻望天树的致危原因、有效地保护 这一珍稀濒危树种和退化次生林的恢复等提供幼苗生态学方面的理论依据。 相似文献
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