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991.
观察为期4周模拟失重对大鼠心肌收缩性能与收缩蛋白性质的影响,发现模拟失重大鼠左心室乳头肌等长收缩的力学特征发生下列变化:发展张力峰值降低29%(P〈0.01);达到张力峰值的时间延长10%(P〈0.05);舒张一半的时间缩短11%,但未达到显著水平(P〉0.05)。心肌力学参数的这些变化表明模拟失重使大鼠心肌收缩性能降低。进一步研究显示,模拟失重大鼠左室心肌肌原纤维Ca^2+,Mg^2+-ATP酶 相似文献
992.
Preference of a revolving target to a stationary one by the big brown bat, Eptesicus fuscus 总被引:1,自引:0,他引:1
W P Zhang P H Jen 《Proceedings of the National Science Council, Republic of China. Part B, Life sciences》1984,8(3):222-228
Utilizing a three-ramp platform, we studied the detection of a revolving and a stationary target in the presence of background clutter by trained Eptesicus fuscus. During the test, the mean amplitude of echo from either target was always larger than that of the background echoes at the bat-to-target distance of 30, 70 and 100 cm. The amplitude of the echo reflected back from a revolving target was modulated between a maximum and a minimum value. An electric motor was used to revolve a target. The frequency contents of the motor noise were mostly below 1 kHz. While the total percent response of approaching either target is always more than 90% at every bat-to-target distance tested, the bats approach a revolving target more frequently than a stationary one. Echolocation pulses emitted by the bats during the test were recorded and analyzed. The bats shortened their pulse durations and interpulse intervals and lowered the frequency contents as they entered into the crawling phase from the searching phase. Potential interference of background echoes and ambient noise with the performance of the bats is discussed. The preference of a revolving target to a stationary one by the bats is perhaps due to the fact that a revolving target has a higher releasing value than a stationary one does. 相似文献
993.
Antibodies against aflatoxin Q1 (AFQ1) were obtained from rabbits after immunization of either AFQ1-hemisuccinate or AFQ2a conjugated to bovine serum albumin. Both radioimmunoassay and enzyme-linked immunosorbent assaY (ELISA) were used for the determination of antibody titers and specificities. Antibodies obtained from rabbits after immunization with AFQ1-hemisuccinate-bovine serum albumin had the highest affinity to aflatoxin B1, whereas antibodies obtained from rabbits after immunization with AFQ2a-bovine serum albumin bound most effectively with AFQ2a. AFQ2a antibody was selected for the subsequent direct and indirect ELISA for the detection of AFQ1 in biological fluids. When AFQ2a-peroxidase and AFQ2a antibody were used, direct ELISA was able to detect as low as 2 ppb (ng/ml) of AFQ1 spiked in the urine samples that had been subjected to a Sep-Pak cleanup treatment. In indirect ELISA in which the antigen (AFQ2a-bovine serum albumin) was coated to the solid phase followed by reaction with rabbit antibody and goat anti-rabbit immunoglobulin G-peroxidase conjugate, 50-fold less antibody was used without sacrificing sensitivity. Recoveries of AFQ1 added to urine samples (2 to 40 ppb) were 46.3 to 73% and 65.8 to 85.8% for direct and indirect ELISA, respectively. 相似文献
994.
995.
Summary Two new variants of alpha-1-antitrypsin were found in a Chinese population by isoelectric focusing in polyacrylamide gel. They have been named Lbeijing (PI*LBEI) and Jhouyao (PI*JHOU) respectively. With the samples reduced and alkylated, both the variants were anodal to M1 and cathodal to L. Omitting the alkylation step, however, the relative mobilities of L and Jhouyao were altered. Under this condition, a characteristic of Jhouyao was revealed by isoelectric focusing in immobilized pH gradient 4.4–4.9, i.e., while its band 6 became anodal to L, band 4 was still cathodal to L. 相似文献
996.
997.
998.
鄂东南早白垩世灵乡群孢粉组合 总被引:1,自引:0,他引:1
张振来 《Acta Botanica Sinica》1984,(6)
本文根据从大冶灵乡-陈重山剖面的中部、灵乡狮子山东侧采坑和鄂城太和1孔的相当层位中所获得的孢粉组合(共67属120余种,其中新种9个,新联合2个),认为灵乡群孢粉组合属于 Classopollis、Psophosphaera-Cicatricosisporites、Schizaeoisporites-没有或极个别的出现被子植物花粉的组合类型,其地质时代应为早白垩世早期-中期(凡兰吟期-巴列姆期)。并推测鄂东南地区当时的气候属于偏干旱的热带-亚热带型。 相似文献
999.
新型有原始肢突胴甲鱼的发现及胴甲鱼早期演化的初步探讨 总被引:1,自引:1,他引:0
本文记述的曲靖始突鱼(Procondylolepis qujingensis gen.et sp.nov.)是近几年在云南曲靖早泥盆世地层中发现的有肢突胴甲鱼一原始类型。它和已知胴甲鱼(包括早泥盆世无肢突的和中、晚泥盆世有“盔”状肢突的)不同的最大特点是在其肩带与胸鳍相接的肩关节处有原始的肢突和简单的关节窝;胸鳍甲近端的关节区很小。它展现出胴甲鱼类这一高度特化、长期使人迷惑不解的肢突,在胴甲鱼演化史上发展变化的梗概,填补了肢突从无到有中间的缺环,使人了解到胸鳍的具体结构。文中主要根据肢突的有无和特化程度等,对胴甲鱼早期演化史作了初步探讨,将胴甲鱼分为无肢突超目(Abrachicondylia)和有肢突超目(Brachicondylia)两大部分。始突鱼则代表有肢突超目一早期成员。 相似文献
1000.
福建东山及附近岛屿岩相潮间带海藻生态的初步研究 总被引:4,自引:0,他引:4
本文根据国家海洋局第三海洋研究所和福建省科委海洋组于1961—1964年在东山及其附近岛屿的调查资料整理而成,目的在于探讨海藻在该地区潮间带分布的特点,为海藻资源的开发以及生态学研究提供某些基本资料。 调查地点有东山本岛的城关、沃角、宫前、歧下和附近的对面屿、大澎屿、塔屿、白屿、外海的兄弟屿等近十处。在普查基础上,着重于城关、对面屿、白屿和沃角分别设A、B、C、D四个断面,进行定量计算(见图1)。 相似文献