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881.
P.A.Závodszky B.Arend D.Cole J.DeKamp M.Doleans G.Machicoane F.Marti P.Miller J.Moskalik W.Nurnberger J.Ottarson M.Steiner J.Stetson J.Vincent X.Wu A.Zeller Q.Zhao 《中国物理 C》2007,31(Z1):18-22
Since the last ECR Workshop,NSCL/MSU has been involved in a vigorous ECR ion source R&D program,which resulted in the construction of an off-line test ECR ion source(ARTEMIS-B)for new beam development and ion optics studies.Also the design and partial completion of a 3rd generation,fully superconducting ECR ion source,SuSI has been accomplished.This paper is an overview of the construction projects and the different R&D activities performed with the existing ion sources.These activities include development of metallic ion beam production methods using evaporation with resistive and inductive ovens and sputtering of very refractory metals.Ion optics developments include testing different focusing elements(magnetic solenoid lens,electrostatic quadrupole triplet lens,Einzel lens,electrostatic double doublet quadrupole combined with an octupole lens),and different beam forming and diagnostics devices.The detailed results will be presented at the workshop in separate talks and posters. 相似文献
882.
In this article we study the interface generated by the collision between two crystals growing layer by layer on a one-dimensional
substrate through random decomposition of particles. We relate this interface with the notion of β-path in an equivalent directed
polymer model and, by using asymptotics results from J. Baik and E. Rains, J. Stat. Phys., 100:523–541 (2000). and some hydrodynamic tools introduced by E. Cator and P. Groeneboom, Ann. Probab., 33:879–903 (2005), we derive a law of large numbers for such a path and obtain some bounds for its fluctuations.
2000 Mathematics Subject Classification: 60C05, 60K35 相似文献
883.
A new excitation mechanism for interstellar Class II methanol masers—maser without population inversion is argued. The 107 GHz
masers is taken as an example to demonstrate that our new mechanism is associated with astronomical conditions. 相似文献
884.
R. Alarcon the BLAST Collaboration 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):588-592
Measurements of the electric and magnetic form factors of the nucleon present a sensitive test of nucleon models and QCD-inspired
theories. A precise knowledge of the neutron form factors at low Q2 is also essential to reduce the systematic errors of parity violation experiments. At the MIT-Bates Linear Accelerator Center,
the nucleon form factors have been measured by means of scattering of polarized electrons from vector-polarized hydrogen and
deuterium. The experiment used the longitudinally polarized stored electron beam of the MIT-Bates South Hall Ring along with
an isotopically pure, highly vector-polarized internal atomic hydrogen and deuterium target provided by an atomic beam source.
The measurements have been carried out with the symmetric Bates Large Acceptance Spectrometer Toroid (BLAST) with enhanced
neutron detection capability. 相似文献
885.
R. Ferrer K. Blaum M. Block F. Herfurth J. Ketelaer Sz. Nagy D. Neidherr C. Weber 《The European physical journal. Special topics》2007,150(1):347-348
The Penning-trap mass spectrometer SHIPTRAP at GSI is designed to provide clean and cooled beams of singly charged radioactive
ions produced in fusion-evaporation reactions and separated in-flight by the velocity filter SHIP. The scientific goals include
mass spectrometry, atomic and nuclear spectroscopy, and chemistry of transuranium species which are not available at ISOL-
or fragmentation facilities Penning-trap based mass measurements on radionuclides relies up to now on the destructive time-of-flight
ion-cyclotron-resonance method. One of the main limitations to the experimental investigations is the low production rate
of most of these exotic nuclides, for which the use of this detection scheme is not applicable. A sensitive and non-destructive
method, like the narrow-band Fourier Transform ion-cyclotron-resonance technique, is ideally suited for the identification
and characterization of these species. A new cryogenic trap setup for SHIPTRAP exploiting this detection technique as well
as some results of first preparatory tests are presented. 相似文献
886.
Part obsolescence is a common problem across industries, from avionics and military sectors to most original equipment manufacturers serving industrial markets. When a part supplier announces that a part will become obsolete, the OEM can choose from a number of sourcing options. In practice, the three most commonly adopted mitigation strategies are: (1) a lifetime, or life-of-type (LOT), buy from the original supplier; (2) part substitution, which finds a suitable alternative; and (3) line redesign, which modifies the production line to accommodate a new part. We first develop a framework incorporating fixed cost, variable cost, leadtime, demand uncertainty and the discount rate to directly compare and characterize these three sourcing strategies in a static context. We next formulate an integrated sourcing approach that starts with a bridge buy and may continue with part substitution or line redesign when the originals parts are depleted. Through numerical studies, we identify the joint impact of the problem parameters on the static and integrated sourcing strategies and the optimal choice among them. While the integrated sourcing approach outperforms the static ones in many cases it is not a dominant strategy. 相似文献
887.
It’s still a challenge for mass spectrometers (MS) to analyze samples in non-volatile salts systems. On the one hand, non-volatile salts are easy to crystallize, which will seriously contaminate and clog the transmission system of mass spectrometry, such as capillaries, ion transfer tubes, sampling cones, etc., thus the analysis results can be affected and the MS can be damaged. On the other hand, non-volatile salts always bring ion suppression, which significantly reduces the signal intensity of the analytes. At the same time, the mass spectrum will be dominated by a large number of salt cluster peaks, interfering with the discrimination of charge state. Recently, different methods have been developed to solve above two problems. This article reviewed the present research progress of mass spectrometry analysis for salt-containing samples, focusing on the role of conventional ion source modification and ambientionization mass spectrometry in the analysis of salt-containing samples. Pretreatment methods were also summarized briefly. Finally, the development tendency of mass spectrometry analysis for salt containing samples is predicted and prospected. © 2023, Youke Publishing Co.,Ltd. All rights reserved. 相似文献
888.
Loss prediction of three-level amplified spontaneous emission sources in radiation environment 下载免费PDF全文
A model of three-level amplified spontaneous emission (ASE) sources, considering radiation effect, is proposed to predict radiation induced loss of output power in radiation environment. Radiation absorption parameters of ASE sources model are obtained by the fitting of color centers generation and recovery process of gain loss data at lower dose rate. Gain loss data at higher dose is applied for self-validating. This model takes both the influence of erbium ions absorption and photon bleaching effect into consideration, which makes the prediction of different dose and dose rate more accurate and flexible. The fitness value between ASE model and gain loss data is 99.98%, which also satisfies the extrapolation at the low dose rate. The method and model may serve as a valuable tool to predict ASE performance in harsh environment. 相似文献
889.
S. Gammino G. Ciavola F. Consoli S. Barbarino L. Celona D. Mascali 《辐射效应与固体损伤》2013,168(10-12):715-722
There is a clear evidence that the combination of ability to produce intense beams of highly charged heavy ions and of reliability, stability and low emittance can be guaranteed only by an adequate design of electron cyclotron resonance ion sources (ECRIS). Following the roadmap defined by Geller's scaling laws (1987) and the high B-mode concept (1990), the evolution of ECRIS has been steady and it amounted to about one order of magnitude per decade, as for high charge state currents. A further increase is possible according to the standard model of ECR sources unless technological problems may limit it in the future. Some sources are in the commissioning or construction phase to get the milliampere level for highly charged heavy ions, and some limitations have been already found but the possibility to get a further step forward remains unchanged. This paper presents the flashbacks of previous relevant experiences, along with the perspectives for higher current production in the years after 2010. 相似文献
890.
The possible use of a simplified UV absorption spectroscopic method for dosimetry of bioactive antirachitic UV radiation has
been analyzed. The method is based on the observation of the phototransformation kinetics of the provitamin D3 primary molecule in ethanol (in vitro vitamin D3 synthesis model) by measuring the decrease in the optical density at a fixed wavelength during UV exposure. The method can
be used successfully for artificial UV sources with a constant radiation spectrum. However, such a technique turns out to
be inapplicable to solar UV dosimetry in view of the variability of the solar UV spectrum that results in a varying rate of
formation of irreversible photoproducts.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 256–260, March–April, 2009. 相似文献