检索结果-南通市图书馆

Quantitative evaluation of LAL productivity of colloidal nanomaterials:Which laser pulse width is more productive,ergonomic,and economic?

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第7期31卷 23-33页

作者： Alena Nastulyavichus Nikita Smirnov Sergey Kudryashov P.N.lebedev physical institute of the Russian Academy of Sciences MoscowRussia

Near-IR(wavelength≈1μm)laser ablation of bulk,chemically-inert gold in water was compared for different laser pulse width in broad the range of 300 fs–100 ns,comparing a number of key ablation characteristics:mass loss,singleshot crater volume and extinction coefficient of the generated colloidal solutions taken in the spectral ranges of interband transitions and localized plasmon *** to related air-based ablation results,at the given fluences laser ablation in the liquid resulted in the maximum ablation yield per unit energy and maximum NP yield per pulse and per unit energy for the picosecond lasers,occurring at subcritical peak pulse powers for laser *** self-focusing effect was demonstrated to yield in incomplete,effectively weaker focusing in the water filaments of ultrashort laser pulses with supercritical peak powers,comparing to linear(geometrical)focusing at sub-critical peak *** the other,nanosecondpulse extreme the high ablation yield per pulse,but low ablation yield per unit energy and low NP yield per pulse and per unit energy were related to strong ablation plasma screening,providing mass removal according to the well-established scaling relationships for *** comparison of the ablation and nanoparticle generation efficiency versus the broad fs–ns laser pulse width range was enabled in terms of productivity,economicity,and ergonomicity,using the proposed universal quantitative criteria.

关键词： laser ablation of gold in liquid ablated mass critical power for self-focusing filamentation

The effects of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents:a meta-analysis

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第5期20卷 1513-1520页

作者： Xueyun Shao Longfei He Yangyang Liu physical Education School Shenzhen UniversityShenzhenGuangdong ProvinceChina Shenzhen institute of Neuroscience ShenzhenGuangdong ProvinceChina

Brain-derived neurotrophic factor is a crucial neurotrophic factor that plays a significant role in brain health. Although the vast majority of meta-analyses have confirmed that exercise interventions can increase brain-derived neurotrophic factor levels in children and adolescents, the effects of specific types of exercise on brain-derived neurotrophic factor levels are still controversial. To address this issue, we used meta-analytic methods to quantitatively evaluate, analyze, and integrate relevant studies. Our goals were to formulate general conclusions regarding the use of exercise interventions, explore the physiological mechanisms by which exercise improves brain health and cognitive ability in children and adolescents, and provide a reliable foundation for follow-up research. We used the Pub Med, Web of Science, Science Direct, Springer, Wiley Online Library, Weipu, Wanfang, and China National Knowledge Infrastructure databases to search for randomized controlled trials examining the influences of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents. The extracted data were analyzed using Review Manager 5.3. According to the inclusion criteria, we assessed randomized controlled trials in which the samples were mainly children and adolescents, and the outcome indicators were measured before and after the intervention. We excluded animal experiments, studies that lacked a control group, and those that did not report quantitative results. The mean difference(MD;before versus after intervention) was used to evaluate the effect of exercise on brain-derived neurotrophic factor levels in children and adolescents. Overall, 531 participants(60 children and 471 adolescents, 10.9–16.1 years) were included from 13 randomized controlled trials. Heterogeneity was evaluated using the Q statistic and I^(2) test provided by Review Manager software. The meta-analysis showed that there was no heterogeneity among the studies(P = 0.67,

关键词： adolescents brain-derived neurotrophic factor children exercise meta-analysis randomized controlled trials

NH_(3)laser THz emission under optical pumping by“long”(~100μs)CO_(2)laser pulses

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2023年第2期21卷 133-137页

作者： Andrey Alekseevich Ionin Igor Olegovich Kinyaevskiy Yuri Mikhailovich Klimachev Andrey Yurievich Kozlov Darya Ivanovna Kormashova Andrey Alexandrovich Kotkov Yury Alekseevich Mityagin Sergey Alexandrovich Savinov Adilya Maratovna Sagitova Dmitry Vasilievich Sinitsyn Maxim Vladimirovich Ionin P.N.lebedev physical institute of the Russian Academy of Sciences Moscow 119991Russia

Terahertz(THz)NH_(3) lasing with optical pumping by electron-beam-sustained discharge“long”(~100μs)CO_(2) laser pulses was *** NH3laser emission pulses and the“long”pulses of the CO_(2) pump laser were simultaneously measured with nanosecond response *** NH3 lasing duration and its delay with respect to the pump pulse were measured for various CO_(2) laser pulse *** the CO_(2) laser pump line 9R(30),three wavelengths of 67.2,83.8,and 88.9μm were *** the CO_(2) laser pump line 9R(16),only a single NH3 laser line with a wavelength of 90.4μm was detected.

关键词： NH3 laser CO_(2)laser terahertz emission nanosecond response time

Review on high repetition rate and mass production of the cryogenic targets for laser IFE

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2017年第2期5卷 28-51页

作者： I.V.Aleksandrova E.R.Koresheva lebedev physical institute Russian Academy of SciencesMoscow119991Russia National Research Nuclear University MEPhl(moscow Engineering Physics institute) Moscow115409Russia

In inertial fusion energy(IFE) research, a considerable attention has recently been focused on the issue of large target fabrication for MJ-class laser facilities. The ignition and high-gain target designs require a condensed uniform layer of hydrogen fuel on the inside of a spherical shell. In this report, we discuss the current status and further trends in the area of developing the layering techniques intended to produce ignition, and layering techniques proposed to high repetition rate and mass production of IFE targets.

关键词： free-standing and line-moving targets high-repetition-rate fuel supply inertial fusion energy target mass production

Investigation of thermal evolution of nanodomain structures in nonlinear barium sodium niobate crystals

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2008年第2期6卷 143-145页

作者： S.V.Ivanova P.N.lebedev physical institute of RAS Leninsky pr.53 Moscow 119991Russia

By the 90° elastic light scattering investigation and far field observation in the range of 20 - 800 ℃, the relation between behavior of light scattering anomalies and evolution of nanodomain structures in lattice of barium sodium niobate （Ba2NaNb5O15, BSN） crystal was clarified. The correlation between anomalies on the temperature curves of the elastic light scattering intensity and temperature transformations of nanodomains was studied by X-ray and electron microscope methods. Phase transition near 500 ℃ and movement in field of scattering light could be explained by appearance of a new incommensurate phase.

关键词： Elastic scattering Light fields Light intensity Light scattering Transmission electron microscopy X ray microscopy

LOGARITHMIC MOMENTS AS NEW CHARACTERISTICS FOR LARGE MULTIPLICITY FLUCTUATIONS IN SMALL RAPIDITY WINDOWS

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1990年第5期7卷 204-207页

作者： Igor M.Dremin WU Yuanfang LIU Lianshou institute of Particle Physics Huazhong Normal UniversityWuhan 430070 P.N.lebedev physical institute MoscowUSSR

The behavior of logarithmic moments of particle distributions in different rapidity windows is discussed for pp and PA collisions at high *** special role of those events,having no-particle in the rapidity window,is s... 详细信息

关键词： particle logarithmic MULTI

New Features of the Pulsar B0950+08 Radiation at the Frequency of 111 MHz

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第3期22卷 88-99页

作者： V.M.Malofeev I.F.Malov O.I.Malov D.A.Teplykh P.N.lebedev physical institute of the Russian Academy of Sciences Leninskii pr.53Moscow119991Russia

Results of long time observations of the pulsar B0950+08 are *** observations were carried out at the LPA radio telescope at the frequency of 111 MHz from January of 2016 to May of 2019(450 days).A strong variability in emission of this pulsar has been detected with changes in signal to noise ratios hundreds of *** of the long-time flux density variability can be explained by refractive scintillations in the interstellar *** existence of radiation between the interpulse(IP)and main pulse(MP)was *** was more powerful than at high *** detected the unusual IP and precursor(Pr)radiation on 2017 August *** the basis of 65 strong IPs we found the correlations between energies of IP and Pr and between the phase of IP and the distance Pr–*** is shown that the observed peculiarities of this pulsar can be explained in the frame of the aligned rotator *** estimated distances of radiation levels from the center of the neutron *** calculated value of the initial period of 0.2 s means that not all pulsars are born with millisecond *** large age of the pulsar(6.8 million years)and the small angle between its magnetic moment and the rotation axis(less than 20°)confirm the suggestion related to pulsar evolution with respect to alignment.

关键词： (stars:)pulsars:individual(PST B0950+08) radiation mechanisms:general (stars:)pulsars:general

Uncertainty in measurements of the distances of scattering screens in pulsar observations

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2018年第8期18卷 117-120页

作者： Evgeny N.Fadeev lebedev physical institute Astro Space Center

In our previous paper we investigated properties of the ionized interstellar medium in the direction of three distant pulsars; B1641-45, B1749-28 and B1933＋16. We found that uniformly dis- tributed scattering material cannot explain measured temporal and angular broadening. We applied a model for a thin scattering screen and found the distances to the scattering screens in all directions. In this paper, we consider more complicated models of scattering material distribution, such as models containing both a uniformly distributed medium and thin screen. Based on these models, we estimate the accuracy of localization of scattering screens and the possible relative contribution of each scattering component.

关键词： ISM structure - pulsars general - scattering

Sky location of massive black hole binaries in the foreground of Galactic white dwarf binaries

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 97-108页

作者： Pan Guo Hong-Bo Jin Cong-Feng Qiao Yue-Liang Wu The International Centre for Theoretical Physics Asia-Pacific University of Chinese Academy of Sciences The School of physical Sciences University of Chinese Academy of Sciences institute for Frontiers in Astronomy and Astrophysics Beijing Normal University National Astronomical Observatories Chinese Academy of Sciences institute of Theoretical Physics Chinese Academy of Sciences

For space-based gravitational wave （GW） detection,the main noise source for massive black hole binaries （MBHBs） is attributed to approximately 10～7double white dwarf binaries in the *** a GW source,the amplitude of the detector response,recorded by a space-based gravitational wave detector,exhibits a modulation effect with a year period when observing the source from various orbital *** the adverse conditions mentioned above,where there is a strong foreground noise and annual modulation in the signals,we employed the wavelet transform and the strong-amplitude relevant orbital position search methods,which allows the weak MBHB sources to achieve higher locating *** detail,for two MBHB sources of lower intensity,the precision of luminosity distance,represented by the ratio ?DL/DLat the 95%confidence level,is enhanced by factors of ～*** angular resolutions,denoted by??s,are enhanced by a factor of ～*** improvements increase the number of detectable GW sources,facilitate multi-messenger follow-up observations and provide constraints on the cosmological constant.

关键词： space-based gravitational wave detection gravitational waves massive black hole binaries