AIM To study the effect of cholecystokinin-octapeptide（CCK-8）and secretin on contractileactivity of isolated gastric muscle strips inguinea pigs.METHODS Each isolated gastric muscle stripwas suspended in a tissue ch...AIM To study the effect of cholecystokinin-octapeptide（CCK-8）and secretin on contractileactivity of isolated gastric muscle strips inguinea pigs.METHODS Each isolated gastric muscle stripwas suspended in a tissue chamber containing5 mL Krebs solution constantly warmed by waterjacked at 37℃ and supplied with a mixed gas of95% O<sub>2</sub> and 5% CO<sub>2</sub> After incubating for lhunder 1 g tension,varied concentrations of CCK-8 and secretin were added respectively in thetissue chamber and the contractile response wasmeasured isometrically on ink-writing recorders.RESULTS CCK-8 could increase①all regionalcircular and longitudinal muscular tension at rest（fundus LM 19.7%±2.1%,P【0.01;fundus CM16.7%±2.2%,P【0.01;gastric body LM 16.8%±2.3%,P【0.01;body CM 12.7%±2.6%,P【0.01;antrum LM 12.3%±1.3%,P【0.01;antrum CM 16.7%±4.5%,P【0.01;pylous CM12.7%±5.0%,P【0.05）;②contractilefrequencies of body LM,both LM and CM ofantrum and pylorus CM（5.1/min±0.2/min to5.6/min±0.2/min,5.9/min±0.2/min to 6.6/min±0.l/min,5.4/min±0.3/min to 6.3/min±0.4/rain,1.3/min±0.2/min to 2.3/min±0.3/min,respectively,P【0.05）;③the mean contractileamplitude of antral circular muscle（58.6%±18.4%,P【0.05）and ④the motility index ofpylorus CM（145.0%±23.8%,P【0.01）,butdecrease the mean contractile amplitude ofgastric body and antral LM（-10.3%±3.3%,-10.5%±4.6%,respectively,P【0.05）.All the CCK-8 effects were not blocked by atropine orindomethacin.Secretin had no effect on gastricsmooth muscle activity.CONCLUSION CCK-8 possessed bothexcitatory and inhibitory action on contractileactivity of different regions of stomach in guineapigs.Its action was not mediated via cholinergicM receptor and endogenous prostagiandinreceptor,展开更多
Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are ...Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are very sensitive to phase transitions, relaxation process of point defects, domain walls and their mobility, which have severe effect on ferroelectric properties. These make them become very good means to investigate substantial information on structural features and to explore the fundamental principles in ferroelectric materials and their applications. In this paper, the dielectric and internal friction measurement were used to investigate the behaviors for point defects and phase transition in ferroelectric ceramics such as Bi_ 4-x La_ x Ti_ 3 O_ 12 , Bi_ 4 Ti_ 3-y Nb_ y O_ 12 , SrBi_ 2 Ti_ 2 O_ 9 , PbZr_ x Ti_ 1-x O_ 3 ,_ PMN-PT. They were used to clarify the mechanism for some ferroelectric behaviors.展开更多
基于前期逐小时黑体温度(Temperature of Black Body, TBB)资料对16个暖季高原中尺度对流系统(Mesoscale Convective System, MCS)的统计结果,文章首先利用客观标准选取了同类的11个长生命史高原东移MCS个例,然后,利用这些MCS个例的合...基于前期逐小时黑体温度(Temperature of Black Body, TBB)资料对16个暖季高原中尺度对流系统(Mesoscale Convective System, MCS)的统计结果,文章首先利用客观标准选取了同类的11个长生命史高原东移MCS个例,然后,利用这些MCS个例的合成来驱动中尺度数值模式WRF(Weather Research and Forecasting Model)进行半理想的数值模拟(即基于实际个例的理想模拟)与敏感性试验,结合分析与动力诊断,从共性上研究了一类长生命史高原东移MCS的演变特征及内在机理.主要结论如下:(1)在对流层高层,此类高原MCS的生成区位于高空急流以南的辐散区,在对流层中层,其生成区主要位于高原东部西风带短波槽槽区附近的暖平流中,在对流层低层,它的生成区表现为对流不稳定层结.高原MCS的生成伴随着其气旋式涡度的快速增长,辐合项以及倾斜项是对流层中低层正涡度的主要制造项,对流活动所导致的向上的正涡度输送是高原MCS快速向上伸展的主要原因.(2)高原MCS的东移过程经历了与高原东部准静止维持高原涡的耦合与解耦过程.在两者耦合期,高原MCS有利于高原涡维持较强的辐合与上升运动,这有助于涡旋的持续;随着高原MCS移出高原,其与高原涡解耦,受此影响,高原涡的上升运动显著减弱,向上的正涡度输送大大减弱,这与负的倾斜项一起,共同导致了高原涡的消亡.(3)高原MCS移出高原后,由于高原地表直接作用在MCS底部的强感热加热消失, MCS首先减弱;随后,在高原东部短波槽的影响下,高原MCS再次迅速发展.对流层中低层辐合项的涡度制造以及对流活动对涡度的向上输送是高原MCS再次发展的主导因子.(4)降水凝结潜热释放是长生命史高原东移MCS生成和发展的必要条件,高原MCS一方面可以通过直接产生降水对高原东部以及部分下游地区产生影响;另一方面,它还可以通过对高原及其周边地区大尺度环境场的调节来对更大范围下游地区的降水进行间接的影响.展开更多
基金the Natural Science Foundation of Gansu Province,No.ZR-94-085.
文摘AIM To study the effect of cholecystokinin-octapeptide（CCK-8）and secretin on contractileactivity of isolated gastric muscle strips inguinea pigs.METHODS Each isolated gastric muscle stripwas suspended in a tissue chamber containing5 mL Krebs solution constantly warmed by waterjacked at 37℃ and supplied with a mixed gas of95% O<sub>2</sub> and 5% CO<sub>2</sub> After incubating for lhunder 1 g tension,varied concentrations of CCK-8 and secretin were added respectively in thetissue chamber and the contractile response wasmeasured isometrically on ink-writing recorders.RESULTS CCK-8 could increase①all regionalcircular and longitudinal muscular tension at rest（fundus LM 19.7%±2.1%,P【0.01;fundus CM16.7%±2.2%,P【0.01;gastric body LM 16.8%±2.3%,P【0.01;body CM 12.7%±2.6%,P【0.01;antrum LM 12.3%±1.3%,P【0.01;antrum CM 16.7%±4.5%,P【0.01;pylous CM12.7%±5.0%,P【0.05）;②contractilefrequencies of body LM,both LM and CM ofantrum and pylorus CM（5.1/min±0.2/min to5.6/min±0.2/min,5.9/min±0.2/min to 6.6/min±0.l/min,5.4/min±0.3/min to 6.3/min±0.4/rain,1.3/min±0.2/min to 2.3/min±0.3/min,respectively,P【0.05）;③the mean contractileamplitude of antral circular muscle（58.6%±18.4%,P【0.05）and ④the motility index ofpylorus CM（145.0%±23.8%,P【0.01）,butdecrease the mean contractile amplitude ofgastric body and antral LM（-10.3%±3.3%,-10.5%±4.6%,respectively,P【0.05）.All the CCK-8 effects were not blocked by atropine orindomethacin.Secretin had no effect on gastricsmooth muscle activity.CONCLUSION CCK-8 possessed bothexcitatory and inhibitory action on contractileactivity of different regions of stomach in guineapigs.Its action was not mediated via cholinergicM receptor and endogenous prostagiandinreceptor,
文摘Ferroelectric materials have enormous potential applications in advanced techniques. However, there are still many problems in its practical application. Dielectric and mechanical (internal friction) measurements are very sensitive to phase transitions, relaxation process of point defects, domain walls and their mobility, which have severe effect on ferroelectric properties. These make them become very good means to investigate substantial information on structural features and to explore the fundamental principles in ferroelectric materials and their applications. In this paper, the dielectric and internal friction measurement were used to investigate the behaviors for point defects and phase transition in ferroelectric ceramics such as Bi_ 4-x La_ x Ti_ 3 O_ 12 , Bi_ 4 Ti_ 3-y Nb_ y O_ 12 , SrBi_ 2 Ti_ 2 O_ 9 , PbZr_ x Ti_ 1-x O_ 3 ,_ PMN-PT. They were used to clarify the mechanism for some ferroelectric behaviors.
文摘基于前期逐小时黑体温度(Temperature of Black Body, TBB)资料对16个暖季高原中尺度对流系统(Mesoscale Convective System, MCS)的统计结果,文章首先利用客观标准选取了同类的11个长生命史高原东移MCS个例,然后,利用这些MCS个例的合成来驱动中尺度数值模式WRF(Weather Research and Forecasting Model)进行半理想的数值模拟(即基于实际个例的理想模拟)与敏感性试验,结合分析与动力诊断,从共性上研究了一类长生命史高原东移MCS的演变特征及内在机理.主要结论如下:(1)在对流层高层,此类高原MCS的生成区位于高空急流以南的辐散区,在对流层中层,其生成区主要位于高原东部西风带短波槽槽区附近的暖平流中,在对流层低层,它的生成区表现为对流不稳定层结.高原MCS的生成伴随着其气旋式涡度的快速增长,辐合项以及倾斜项是对流层中低层正涡度的主要制造项,对流活动所导致的向上的正涡度输送是高原MCS快速向上伸展的主要原因.(2)高原MCS的东移过程经历了与高原东部准静止维持高原涡的耦合与解耦过程.在两者耦合期,高原MCS有利于高原涡维持较强的辐合与上升运动,这有助于涡旋的持续;随着高原MCS移出高原,其与高原涡解耦,受此影响,高原涡的上升运动显著减弱,向上的正涡度输送大大减弱,这与负的倾斜项一起,共同导致了高原涡的消亡.(3)高原MCS移出高原后,由于高原地表直接作用在MCS底部的强感热加热消失, MCS首先减弱;随后,在高原东部短波槽的影响下,高原MCS再次迅速发展.对流层中低层辐合项的涡度制造以及对流活动对涡度的向上输送是高原MCS再次发展的主导因子.(4)降水凝结潜热释放是长生命史高原东移MCS生成和发展的必要条件,高原MCS一方面可以通过直接产生降水对高原东部以及部分下游地区产生影响;另一方面,它还可以通过对高原及其周边地区大尺度环境场的调节来对更大范围下游地区的降水进行间接的影响.
