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Effects of Bagging and Bag Removal at Different Times on Quality of Applepear 被引量:5
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作者 孙继军 《Agricultural Science & Technology》 CAS 2016年第8期1799-1801,共3页
[Objective] The aim was to investigate effects of bagging and bag-removing times on quality of applepear. [Method] The seven-year-old applepears were taken as materials to explore effects of bagging and bag-removing t... [Objective] The aim was to investigate effects of bagging and bag-removing times on quality of applepear. [Method] The seven-year-old applepears were taken as materials to explore effects of bagging and bag-removing times on external and internal quality of applepear. [Result] Scientific timing of either bagging or bag removing will improve fruit quality, color expressed by anthocyanin pigments and coloring index, and reduce chlorophyll content, pericarp thickness and fruit dots. [Conclusion] It has determined that the scientific times of applepear bagging and bag removing are 55 d after peak flowering and 13 d prior to harvesting in Fuxin, Liaoning Province. 展开更多
关键词 different times BAGGING Bag removing Applepear Quality of fruit
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EXISTENCE TIME FOR SOLUTIONS OFSEMILINEAR DIFFERENT SPEED KLEIN-GORDONSYSTEM WITH WEAK DECAY DATA IN 1D 被引量:2
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作者 方道元 《Acta Mathematica Scientia》 SCIE CSCD 2002年第1期79-98,共20页
A -4/3|log |-2 result is obtained for the existence time of solutions of semi- linear different speed Klein-Gordon system in one space dimension for weakly decaying Cauchy data, of size , in certain circumstances of ... A -4/3|log |-2 result is obtained for the existence time of solutions of semi- linear different speed Klein-Gordon system in one space dimension for weakly decaying Cauchy data, of size , in certain circumstances of nonlinearity. 展开更多
关键词 Weakly decaying Cauchy data existence time. Klein-Gordon equations with different speeds
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New results on global exponential stability of competitive neural networks with different time scales and time-varying delays 被引量:1
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作者 崔宝同 陈君 楼旭阳 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第5期1670-1677,共8页
This paper studies the global exponential stability of competitive neural networks with different time scales and time-varying delays. By using the method of the proper Lyapunov functions and inequality technique, som... This paper studies the global exponential stability of competitive neural networks with different time scales and time-varying delays. By using the method of the proper Lyapunov functions and inequality technique, some sufficient conditions are presented for global exponential stability of delay competitive neural networks with different time scales. These conditions obtained have important leading significance in the designs and applications of global exponential stability for competitive neural networks. Finally, an example with its simulation is provided to demonstrate the usefulness of the proposed criteria. 展开更多
关键词 competitive neural network different time scale global exponential stability DELAY
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Interdecadal Variations of Phase Delays Between Two Nino Indices at Different Time Scales
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作者 卞建春 杨培才 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2005年第1期122-125,共4页
Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4 (1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that there are two types of perio... Phase delays between two Nino indices-sea surface temperatures in Nino regions 1+2 and 3.4 (1950-2001)-at different time scales are detected by wavelet analysis. Analysis results show that there are two types of period bifurcations in the Nino indices and that period bifurcation points exist only in the region where the wavelet power is small. Interdecadal variation features of phase delays between the two indices vary with different time scales. In the periods of 40-72 months, the phase delay changes its sign in 1977: Nino 1+2 indices are 2-4 months earlier than Nino 3.4 indices before 1977, but 3-6 months later afterwards. In the periods of 20-40 months, however, the phase delay changes its sign in another way: Nino 1+2 indices are 1-4 months earlier before 1980 and during 1986-90, but 1-4 months later during 1980-83 and 1993-2001. 展开更多
关键词 period bifurcations different time scales phase delay interdecadal variation
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Discussion of the Horizontal Intensity of Late Quaternary Fault Activity Along the Tianjingshan Fault Zone in Different Time Intervals and Fault Segments 被引量:1
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作者 Chai Chizhang,Zhang Weiqi,and Jiao DechengSeismological Bureau of Ningxia Hui Autonomous Region,Yinchuan 750001,China 《Earthquake Research in China》 1997年第3期25-32,共8页
By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are disc... By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are discussed in different time intervals and fault segments.The results suggest that the intensity of activity along the fault zone is not strong,but the differences between different time intervals and fault segments since the late Pleistocene have been obvious.The average rates range from 0.23 mm/a to 1.62 mm/a.The largest average rate is 1.40 mm/a,which occurred in the early and middle of late Pleistocene along the western segment of the fault zone.Since the late stage of the late Pleistocene,the center of faulting activity of the fault zone has shifted to the middle segment,and the average slip rates range have changed from 1.30 mm/a to 1.63 mm/a. 展开更多
关键词 Discussion of the Horizontal Intensity of Late Quaternary Fault Activity Along the Tianjingshan Fault Zone in different time Intervals and Fault Segments Activity
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Comparison of the level of thrombus precursor protein in blood plasma between patients with acute cerebral infarction and healthy persons at different time
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作者 Chenghua Xiao Peng Zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第3期258-260,共3页
BACKGROUND: Thrombus precursor protein (TpP) is the index of thrombus activity level, and it is also early referencing index in detecting thrombus diseases. OBJECTIVE: To dynamically observe the changes of TpP lev... BACKGROUND: Thrombus precursor protein (TpP) is the index of thrombus activity level, and it is also early referencing index in detecting thrombus diseases. OBJECTIVE: To dynamically observe the changes of TpP level in blood plasma of patients with acute cerebral infarction at different time after onset, and to compare the differences of plasma TpP level between patients with acute cerebral infarction and healthy persons who received health examination. DESIGN: Controlled observation SETTING: Department of Neurology, Affiliated Hospital of Xuzhou Medical College PARTICIPANTS: Totally 58 patients with acute cerebral infarction who received the treatment in the Department of Neurology, Affiliated Hospital of Xuzhou Medical College between September 2004 and March 2005 were recruited in this study. They all met the diagnostic criteria revised by the 4^th National Conference of Cerebrovascular Disorders in 1995 and were diagnosed by clinical and skull CT and (or) MRI examinations. The patients included 33 male and 25 female aged from 36 to 87 years. Time to onset 〈 6 hours, 6 to 11 hours, 12 to 23 hours, 24 to 48 hours and 〉 48 hours were found in 10,11,14,10 and 13 patients respectively. Another 51 persons who homeochronously received the health body examination in our hospital were recruited, including 34 male and 17 female, aged 38 to 85 years, serving as control group. Patients with cardio-cerebrovascualr diseases or liver and kidney diseases were excluded. All the involved subjects were informed of the detected items. METHODS: About 4 mL venous blood was respectively taken from patients admitted to the hospital within 6 hours, 6 toll hours, 12 to 23 hours, 24 to 48 hours and more then 48 hours after onset, and healthy persons when receiving health examination. The level of TpP in blood plasma was measured with enzymelinked immunosorbent assay. MAIN OUTCOME MEASURES: ① Comparison of the level of plasma TpP between patients and controls;② Comparison of the level of plasma TpP of patients with acute cerebral infarction at different time after onset. RESULTS: Totally 58 patients with acute cerebral infarction and 51 persons who received health examination participated in the result analysis. ①Comparison of plasma TpP level between patients and controls: The plasma TpP level of patients with acute cerebral infarction was significantly higher than that of control group [(16.12±3.28)vs (5.38±1.36) mg/L, t= 20.993, P〈 0.01 ]. ② Comparison of plasma TpP level of patients with acute cerebral infarction at different time after onset: The level of plasma TpP was (12.06±3.06) mg/L within 6 hours, (15.11±3.42) mg/L at 6 to 11 hours, (20.63±4.05) mg/L at 12 to 23 hours, (16.15±3.50) mg/L at 24 to 48 hours and (11.88±3.11) mg/L at more than 48 hours after onset. It increased from the 6^th hour, reached the peak at the 12^th to 23^rd hours, maintained at very high level at the 48= hour and then gradually decreased and recovered to the level within 6 hours after onset. The level of plasma TpP of patients with acute cerebral infarction was signiticantly higher at the 12^th to 23^rd hours after onset and the 24^th to 48^th hours after onset than within 6 hours after onset (t = 13.385, P 〈 0.05). CONCLUSION: ①The level of plasma TpP of patients with acute cerebral infarction is significantly higher than that of persons who received health examination.② Plasma TpP levels of patients with acute cerebral infarction change in wave manner at the different time after onset. 展开更多
关键词 Comparison of the level of thrombus precursor protein in blood plasma between patients with acute cerebral infarction and healthy persons at different time time
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Global Uniform Asymptotic Stability of Competitive Neural Networks with Different-Time Scales and Delay 被引量:1
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作者 李红 吕恕 钟守铭 《Journal of Electronic Science and Technology of China》 2005年第2期126-129,共4页
The global uniform asymptotic stability of competitive neural networks with different time scales and delay is investigated. By the method of variation of parameters and the method of inequality analysis, the conditio... The global uniform asymptotic stability of competitive neural networks with different time scales and delay is investigated. By the method of variation of parameters and the method of inequality analysis, the condition for global uniformly asymptotically stable are given. A strict Lyapunov function for the flow of a competitive neural system with different time scales and delay is presented. Based on the function, the global uniform asymptotic stability of the equilibrium point can be proved. 展开更多
关键词 flow invariance DELAY different time-scales neural network asymptotic stability
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Assessment of the methods for determining net radiation at different time-scales of meteorological variables
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作者 Ni An Sahar Hemmati Yu-Jun Cui 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2017年第2期239-246,共8页
When modeling the soil/atmosphere interaction,it is of paramount importance to determine the net radiation flux.There are two common calculation methods for this purpose.Method 1 relies on use of air temperature,while... When modeling the soil/atmosphere interaction,it is of paramount importance to determine the net radiation flux.There are two common calculation methods for this purpose.Method 1 relies on use of air temperature,while Method 2 relies on use of both air and soil temperatures.Nowadays,there has been no consensus on the application of these two methods.In this study,the half-hourly data of solar radiation recorded at an experimental embankment are used to calculate the net radiation and long-wave radiation at different time-scales(half-hourly,hourly,and daily) using the two methods.The results show that,compared with Method 2 which has been widely adopted in agronomical,geotechnical and geo-environmental applications.Method 1 is more feasible for its simplicity and accuracy at shorter time-scale.Moreover,in case of longer time-scale,daily for instance,less variations of net radiation and long-wave radiation are obtained,suggesting that no detailed soil temperature variations can be obtained.In other words,shorter time-scales are preferred in determining net radiation flux. 展开更多
关键词 Energy balance Net radiation different time-scales Meteorological data
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STUDY ON MIXIS POTENTIAL OF ROTIFER RESTING EGGS ( BRACHIONUS PLICATILIS ) WITH DIFFERENT COLLECTION TIMES AND DIFFERENT PRESERVATION PERIODS
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作者 周利 郑严 相建海 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2001年第3期222-227,共6页
The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clone... The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clones derived from each batch of resting eggs were cultured under the same conditions for 21 days. The percentage of clones appearing resting eggs and the average yield of resting eggs produced from each clone were recorded and statistically analyzed to find the differences between the mixis potential of those resting egg batches. Results showed that different batches of resting eggs had different mictic levels among their descendent clones; but no regular relationship was found between the mixis potential of resting eggs and their collection times/preservation periods. Several internal and external factors that might affect the mixis potential of resting eggs were discussed. 展开更多
关键词 Brachionus plicatilis resting eggs mixis potential collection times preservation periods
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Quantitative Analysis of Flavonoids in Scutellariae Radix of Different Sources and Seasonal Variation by HPLC 被引量:2
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作者 张永煜 郭允珍 +6 位作者 上田博之 针谷羲弘 恩田政行 桥本和则 池谷幸信 罔田稔 丸野政雄 《Journal of Chinese Pharmaceutical Sciences》 CAS 1998年第3期26-29,共4页
The seasonal and source variations of flavonoid contents in Scutellariae Radix were investigated by using the materials collected at the same place in Liaoning Province, China, during three years, 1990~1992, and in s... The seasonal and source variations of flavonoid contents in Scutellariae Radix were investigated by using the materials collected at the same place in Liaoning Province, China, during three years, 1990~1992, and in seven other provinces in China. Four principal flavonoids in the plant roots, i.e., baicalin, baicalein, wogonin 7 O glucuronide and wogonin were analyzed by using a reversed phase chromatographic system with a chemically bonded ODS silica gel column and phosphate buffer methanol (68:32 and 1:1) as mobile phase. The contents of the four compounds combined in the herb collected at Chengde, Hebei Province are the highest. The results show that the best time for harvesting the roots in Liaoning Province is the end of August. 展开更多
关键词 Scutellariae Radix Scutellaria baicalensis Georgi different sources different harvest times
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The Differential Transform
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作者 Eng. Mahmoud Abu Hilal 《Journal of Applied Mathematics and Physics》 2021年第8期1978-1992,共15页
One of the methods of mathematical analysis in many cases makes it possible to reduce the study of differential operators, pseudo-differential operators and certain types of integral operators and the solution of equa... One of the methods of mathematical analysis in many cases makes it possible to reduce the study of differential operators, pseudo-differential operators and certain types of integral operators and the solution of equations containing them, to an examination of simpler algebraic problems. The development and systematic use of operational calculus began with the work of O. Heaviside (1892), who proposed formal rules for dealing with the differentiation operator d/dt and solved a number of applied problems. However, he did not give operational calculus a mathematical basis;this was done with the aid of the Laplace transform;J. Mikusi<span style="white-space:nowrap;">&#324;</span>ski (1953) put operational calculus into algebraic form, using the concept of a function ring <a href="#ref1">[1]</a>. Thereupon I’m suggesting here the use of the integration operator dt to make an extension for the systematic use of operational calculus. Throughout designing and analyzing a control system, we need to treat the functionality of the system with respect to time. The reaction of the system instructs us how to stable it by amplifiers and feedbacks <a href="#ref2">[2]</a>, thereafter the Differential Transform is a good tool for doing this, and it’s a technique to frustrate difficulties we may bump into, also it has the methods to find the immediate reaction of the system with respect to infinitesimal (tiny) time which spares us from the hard work in finding the time dependent function, this could be done by producing finite series. 展开更多
关键词 Operational Calculus time Domain differential Domain Serieses Difference to differential Equation
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Different optical properties in different periodic slot cavity geometrical morphologies
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作者 周静 沈萌 +3 位作者 杜澜 邓彩松 倪海彬 王鸣 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第9期500-506,共7页
In this paper,optical properties of two-dimensional periodic annular slot cavity arrays in hexagonal close-packing on a silica substrate are theoretically characterized by finite difference time domain(FDTD) simulat... In this paper,optical properties of two-dimensional periodic annular slot cavity arrays in hexagonal close-packing on a silica substrate are theoretically characterized by finite difference time domain(FDTD) simulation method.By simulating reflectance spectra,electric field distribution,and charge distribution,we confirm that multiple cylindrical surface plasmon resonances can be excited in annular inclined slot cavities by linearly polarized light,in which the four reflectance dips are attributed to Fabry–Perot cavity resonances in the coaxial cavity.A coaxial waveguide mode TE11 will exist in these annular cavities,and the wavelengths of these reflectance dips are effectively tailored by changing the geometrical pattern of slot cavity and the dielectric materials filled in the cavities.These resonant wavelengths are localized in annular cavities with large electric field enhancement and dissipate gradually due to metal loss.The formation of an absorption peak can be explained from the aspect of phase matching conditions.We observed that the proposed structure can be tuned over the broad spectral range of 600–4000 nm by changing the outer and inner radii of the annular gaps,gap surface topography.Meanwhile,different lengths of the cavity may cause the shift of resonance dips.Also,we study the field enhancement at different vertical locations of the slit.In addition,dielectric materials filling in the annular gaps will result in a shift of the resonance wavelengths,which make the annular cavities good candidates for refractive index sensors.The refractive index sensitivity of annular cavities can also be tuned by the geometry size and the media around the cavity.Annular cavities with novel applications can be implied as surface enhanced Raman spectra substrates,refractive index sensors,nano-lasers,and optical trappers. 展开更多
关键词 cylindrical surface plasmons finite difference time domain Fabry–Perot cavity resonances twodimensional periodical structure
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Research of electromagnetic field in different length left-handed material slab
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作者 LIN Zhen MA Xue-ying +1 位作者 LIANG Chang-hong ZENG Hao 《核聚变与等离子体物理》 EI CAS CSCD 北大核心 2007年第3期256-259,共4页
Finite-difference time-domain(FDTD) method is used to simulate the propagation of electromagnetic wave in left-handed material slab(LHMs) with cold plasma model The effects of optical propagation in the left-handed ma... Finite-difference time-domain(FDTD) method is used to simulate the propagation of electromagnetic wave in left-handed material slab(LHMs) with cold plasma model The effects of optical propagation in the left-handed material compared to convex lens are discussed.The wider the LHMs is,the stronger electric field of focusing image in left-handed material slab is confirmed by the simulation with various slab length.However,the outer image point location would slightly moves to the LHMs side when the length of LHMs is reduced. 展开更多
关键词 电磁场 有限差异时间域 低温等离子体模型 聚焦图像 左手材料平板
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High-precision time and frequency measurement method combining time-space conversion and different frequency phase detection 被引量:4
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作者 DU BaoQiang WANG YanFeng +3 位作者 CUI GuangZhao GUO ShuTing DONG ShaoFeng LIU Dan 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第11期2110-2115,共6页
According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and st... According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and stability of the speed of light and electromagnetic signals during the transmission in space or a specific medium enable the measurement of short time interval which uses the coincidence detection of signal’s transmission delay in length.The measurement precision better than 10 picoseconds can be easily obtained.The method develops the length vernier utilizing the stability of signal’s transmission delay,minimizes the fuzzy region of phase coincidence between the standard frequency signal and the measured signal,approaches the best phase coincidences and therefore improves the measurement precision which is higher than the precision provided by the traditional methods based on frequency processing.Besides,the method costs less than the traditional methods and can also solve the problem of the measurement of super-high frequency.Experimental results show the method can improve the measurement precision to 10 12/s in the time&frequency domain. 展开更多
关键词 time and space conversion delay-time phase shift different phase coincidence detection group phase difference
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Pinning Synchronization of Discrete-Time Complex Networks with Different Time-Varying Delays 被引量:2
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作者 ZHANG Qunjiao WU Xiaoqun LIU Jie 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2019年第6期1560-1571,共12页
This paper investigates pinning synchronization of discrete-time complex networks with differen t time-varying delays.An important lemma is presen ted and proved,t hen detailed analysis is given to yield some synchron... This paper investigates pinning synchronization of discrete-time complex networks with differen t time-varying delays.An important lemma is presen ted and proved,t hen detailed analysis is given to yield some synchronization criteria for this kind of net works.The results provide an effective way to synchronize discrete-time complex networks by reducing control cost.Furthermore,these theoretical results are illustrated by a complex network via two kinds of pinning schemes.Numerical simulations verify the feasibil计y of the proposed methods. 展开更多
关键词 different time-varying delays discrete・time complex networks PINNING SYNCHRONIZATION
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Mild moxibustion at different intervention times on the levels of ET-1 and NO in the uterine tissues of rats with cold-damp coagulation and stagnation type dysmenorrhea 被引量:8
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作者 Xiao-xue SUN Li-yun YANG +7 位作者 Yu-lei LIANG Xin-hua LI Fei GAO Xiao-yi DU Xiao-hong ZHOU Yang CHEN Xue-na LI Li-hong SUN 《World Journal of Acupuncture-Moxibustion》 CSCD 2018年第2期33-38,82,83,共8页
Objective: To observe the differences in analgesic effect of moxibustion at different intervention times on dysmenorrhea rats and explore its effect mechanism.Methods: Forty-five female Wistar rats were randomly div... Objective: To observe the differences in analgesic effect of moxibustion at different intervention times on dysmenorrhea rats and explore its effect mechanism.Methods: Forty-five female Wistar rats were randomly divided into blank control group(group A), model group(group B), pre-moxibustion group(group C), instant moxibustion group(group D) and pre-instant moxibustion group(group E),with 9 rats in each group. Cold-damp coagulation and stagnation type dysmenorrhea models were established. In group C,mild moxibustion on "Shenque(神阙 CV 8) " and"Guanyuan(关元 CV 4)" was carried out from the time after modeling on the 8 th day for 3 consecutive days. In group D, mild moxibustion was given as the same methods with group C after injection with oxytocin on the 11 th day. In group E, mild moxibustion was given as the same methods from the time after modeling on the 8 th day to that after injection with oxytocin on the 11 th day for 4 consecutive days. The writhing behavior and the changes in levels of ET-1 and NO in uterine tissues of rats with dysmenorrhea in each group were observed.Results: Comparison of the latent period: compared with(4.38 ± 1.06) min in group B,the latent period of rats in group C(9.67 ± 1.32) min,group D(11.78 ± 1.30) min and group E(15.00 ± 1.22) min obviously prolonged(all p 0.01). Compared with group C, the latent period of group E obviously prolonged(p 0.01). Compared with group D, the latent period of group E obviously prolonged(p 0.01).Comparison of the writhing times: compared with(4.38 ± 1.06) in group B,the writhing times of rats in group C(9.67 ± 1.32),group D(11.78 ± 1.30) and group E(15.00 ± 1.22) reduced(all p 0.01). Compared with group C,the writhing times of rats in group D and group E reduced(both p 0.01). Compared with group D, the writhing times in group E reduced(p 0.05). Comparison of the total writhing score:compared with(4.38 ± 1.06) in group B,the total writhing score of rats in group C(9.67±1.32),group D(11.78 ± 1.30) and group E(15.00 ± 1.22) decreased(all p 0.01). Compared with group C,the total writhing score of rats in group D and group E decreased(both p 0.01). Compared with group D,the total writhing score of rats in group E decreased(p 0.05). Comparison of ET-1 level: compared with(4.80 ± 0.47) in group A,the ET-1 level in uterine tissues of rats in group B(7.57±0.69) significantly increased(P 0.01). Compared with group B, the ET-1 level in uterine tissues of rats in group C(6.20 ±0.50),group D(5.67 ±0.29) and group E(5.16±0.33) obviously decreased(all p 0.01). Compared with group C, the ET-1 level in uterine tissues of rats in group D and group E obviously decreased(p 0.05, p 0.01). Compared with group D, the ET-1 level in uterine tissues of rats in group Eobviously decreased(p 0.05). Comparison of NO level: compared with(6.63±1.83) in group A, the NO level in uterine tissues of rats in group B(1.62 ±0.58) significantly decreased(p 0.01). Compared with group B, the NO level in uterine tissues of rats in group C(3.60±0.59),group D(4.77 ±0.67) and group E(5.99±0.63) obviously increased(all p 0.01). Compared with group C,the NO level in uterine tissues of rats in group Dand group E obviously increased(p 0.05, p 0.01). Compared with group D, the NO level in uterine tissues of rats in group E obviously increased(p 0.01).Conclusion: The analgesic effect of mild moxibustion at different intervention times on cold-damp coagulation and stagnation type dysmenorrhea rats was different, which was the most significant in pre-instant moxibustion group. One of the mechanisms of action may be related with the adjustment of abnormal levels of ET-1 and NO. 展开更多
关键词 Mild moxibustion different intervention times DYSMENORRHEA Cold-damp coagulation and stagnation type ET-1 NO
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Self-adaptive focusing by time reversal through interface between different media 被引量:9
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作者 WEI Wei WANG Chenghao (Institute of Acoustics, Chinese Academy of Sciences Beijing 100080) 《Chinese Journal of Acoustics》 2000年第1期83-88,共6页
The time reversal is an unique self-adaptive focusing technique important to ultrasonic imaging. In this paper, the principle and the analytic expression of the ultrasound field in the realization of time reversal du... The time reversal is an unique self-adaptive focusing technique important to ultrasonic imaging. In this paper, the principle and the analytic expression of the ultrasound field in the realization of time reversal during the presence of an interface between two media are presented. Experimental results of time reversal are given and found to agree with theoretical ones. 展开更多
关键词 time Self-adaptive focusing by time reversal through interface between different media
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Mapping soil organic matter content using Sentinel-2 syntheticimages at different time intervals in Northeast China
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作者 Chong Luo Wenqi Zhang +1 位作者 Xinle Zhang Huanjun Liu 《International Journal of Digital Earth》 SCIE EI 2023年第1期1094-1107,共14页
Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from ... Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from 2019 to 2022 and integrated the observation results into synthetic materials with four defined time intervals(10,15,20,and 30 d).Then,we used synthetic images corresponding to different time periods to conduct SOM mapping and determine the optimal time interval and time period beforefinally assessing the impacts of adding environmental covariates.The results showed the following:(1)in SOM mapping,the highest accuracy was obtained using day-of-year(DOY)120 to 140 synthetic images with 20 d time intervals,as well as with different time intervals,ranked as follows:20 d>30 d>15 d>10 d;(2)when using synthetic images at different time intervals to predict SOM,the best time period for predicting SOM was always within May;and(3)adding environmental covariates effectively improved the SOM mapping performance,and the multiyear average temperature was the most important factor.In general,our results demonstrated the valuable potential of SOM mapping using multiyear synthetic imagery,thereby allowing detailed mapping of large areas of cultivated soil. 展开更多
关键词 Sentinel-2 environmental covariates baresoilperiod synthetic images different time intervals soilorganic matter
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Study of broadband THz time-domain spectroscopy at different relative humidity levels
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作者 林家任 何宜贞 张希成 《Chinese Optics Letters》 SCIE EI CAS CSCD 2012年第4期78-81,共4页
Two detection techniques of broadband terahertz(THz)time-domain spectroscopy-THz air-biased coherent detection(THz-ABCD;from 0.3 to 14 THz)and electro-optical(EO)detection(from 0.3 to 7 THz)-are both performed... Two detection techniques of broadband terahertz(THz)time-domain spectroscopy-THz air-biased coherent detection(THz-ABCD;from 0.3 to 14 THz)and electro-optical(EO)detection(from 0.3 to 7 THz)-are both performed at several different relative humidity levels.The THz power exponentially decays with the increase in relative humidity.The dynamic range of the main pulse in the time domain linearly decreases as the relative humidity increases from 0%to 40%,and linear fittings show that the slopes are-0.017 and-0.019 for THz-ABCD and EO detection,respectively.Because of the multiple reflections caused by the crystal in the common EO detection,THz-ABCD has better spectral resolution(17 GHz)than that of EO detection(170 GHz).The spectrum of water vapor absorption measured by THz-ABCD is also compared with that measured by the Fourier transform infrared spectroscopy(FTIR). 展开更多
关键词 THZ Study of broadband THz time-domain spectroscopy at different relative humidity levels time
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Fidelity of light storage in warm atomic gases at different storage time
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作者 齐越蓉 高宏 张首刚 《Chinese Optics Letters》 SCIE EI CAS CSCD 2010年第1期1-3,共3页
The fidelity of light with arbitrary polarizations stored in a warm STRb atomic vapor at different storage time is studied. The exponential decay of regeneration efficiency with the storage time is observed and a dete... The fidelity of light with arbitrary polarizations stored in a warm STRb atomic vapor at different storage time is studied. The exponential decay of regeneration efficiency with the storage time is observed and a detectable signal at 300-us storage time is still existed. The storage fidelity at different storage time is well maintained in our experiment. 展开更多
关键词 Fidelity of light storage in warm atomic gases at different storage time EIT PDI
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