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91.
Beker H. Bøggild H. Boissevain J. Cherney M. Dodd J. Esumi S. Fabjan C. W. Fields D. E. Franz A. Hansen K. H. Holzer B. Humanic T. Jacak B. Jayanti R. Kalechofsky H. Kobayashi T. Kvatadze R. Lee Y. Y. Leltchouk M. Lörstad B. Maeda N. Medvedev A. Miake Y. Miyabayashi A. Murray M. Nagamiya S. Nishimura S. Noteboom E. Pandey S. U. Piuz F. Polychronakos V. Potekhin M. Poulard G. Sakaguchi A. Sarabura M. Shigaki K. Simon-Gillo J. Sletten H. Sondheim W. Sugitate T. Sullivan J. P. Sumi Y. van Hecke H. Willis W. J. Wolf K. 《Zeitschrift fur Physik C Particles and Fields》1994,64(2):209-217
K+K+ and K–K– correlations from S+Pb collisions at 200 GeV/c per nucleon and K+K+ correlations from p+Pb collisions at 450 GeV/c per nucleon, are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. Multidimensional fits are performed in order to characterize the kaon-emission volume, which is found to be smaller than the pion-emission volume. 相似文献
92.
Meissner A Sørensen OW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,150(1):100-104
The conventional HNCA pulse sequence suffers from the ambiguity that it cannot distinguish inter- and intraresidue correlations because the one-bond and two-bond J(NC(alpha)) coupling constants are of similar magnitude. This paper presents a novel pulse sequence, sequential HNCA, that leads to a spectrum exhibiting exclusively interresidue correlations. This important sequential information has so far usually been obtained by an HN(CO)CA experiment that for medium field strengths typically also is more sensitive than HNCA. However, for increasing static magnetic fields the chemical shift anisotropy relaxation mechanism of carbonyl carbons becomes more and more efficient, leading to a degradation of the HN(CO)CA sensitivity. Hence there is a point where the sequential HNCA experiment becomes the most sensitive option for sequential N-C(alpha) correlation. 相似文献
93.
Hansen K Andersen JU Hvelplund P Møller SP Pedersen UV Petrunin VV 《Physical review letters》2001,87(12):123401
The exponential law is valid both for decay from a single quantum state into a continuum and for an ensemble maintained in thermal equilibrium. For statistical decay of an ensemble of isolated systems with a broad energy distribution, the exponential decay is replaced by a 1/t distribution. We present confirmation of this decay law by experiments with cluster anions in a small electrostatic storage ring. Deviations from the 1/t law for such an ensemble give important information on the dynamics of the systems. As examples, we present measurements revealing strong radiative cooling of anions of both metal clusters and fullerenes. 相似文献
94.
Bearden IG Bøggild H Boissevain J Christiansen PH Conin L Dodd J Erazmus B Esumi S Fabjan CW Ferenc D Franz A Gaardhøje JJ Hansen AG Hansen O Hardtke D van Hecke H Holzer EB Humanic TJ Hummel P Jacak BV Kaimi K Kaneta M Kohama T Kopytine M Leltchouk M Ljubicic A Lörstad B Maeda N Martin L Medvedev A Murray M Ohnishi H Paic G Pandey SU Piuz F Pluta J Polychronakos V Potekhin M Poulard G Reichhold D Sakaguchi A Schmidt-Sørensen J Simon-Gillo J Sondheim W Sugitate T Sullivan JP Sumi Y Willis WJ 《Physical review letters》2001,87(11):112301
Two-particle interferometry of positive kaons is studied in Pb+Pb collisions at mean transverse momenta
approximately 0.25 and 0.91 GeV/c. A three-dimensional analysis was applied to the lower p(T) data, while a two-dimensional analysis was used for the higher p(T) data. We find that the source-size parameters are consistent with the m(T) scaling curve observed in pion-correlation measurements in the same collisions, and that the duration time of kaon emission is consistent with zero within the experimental sensitivity. 相似文献
95.
96.
Hansen MR Brorson M Bildsøe H Skibsted J Jakobsen HJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,190(2):316-326
The WURST (wideband uniform rate smooth truncation) and hyperbolic secant (HS) pulse elements have each been employed as pairs of inversion pulses to induce population transfer (PT) between the four energy levels in natural abundance solid-state (33)S (spin I=3/2) MAS NMR, thereby leading to a significant gain in intensity for the central transition (CT). The pair of inversion pulses are applied to the satellite transitions for a series of inorganic sulfates, the sulfate ions in the two cementitious materials ettringite and thaumasite, and the two tetrathiometallates (NH(4))(2)WS(4) and (NH(4))(2)MoS(4). These materials all exhibit (33)S quadrupole coupling constants (C(Q)) in the range 0.1-1.0 MHz, with precise C(Q) values being determined from analysis of the PT enhanced (33)S MAS NMR spectra. The enhancement factors for the WURST and HS elements are quite similar and are all in the range 1.74-2.25 for the studied samples, in excellent agreement with earlier reports on HS enhancement factors (1.6-2.4) observed for other spin I=3/2 nuclei with similar C(Q) values (0.3-1.2 MHz). Thus, a time saving in instrument time by a factor up to five has been achieved in natural abundance (33)S MAS NMR, a time saving which is extremely welcome for this important low-gamma nucleus. 相似文献
97.
Bjørn Tore Knudsen 《Czechoslovak Journal of Physics》1997,47(9):925-929
The WA97 experiment is a part of the CERN heavy-ion program. The experiment aims to measure enhanced strangeness production as a signal of the phase transition from a Quark-Gluon Plasma. The first run for the experiment was in the autumn 1994, when CERN accelerated lead-ions in the SPS ring for the first time. The WA97 experiment have used silicon microstrip and pixel detectors with technology which have never been used before. It is shown that even the triply strange can be reliably measured in the experiment. 相似文献
98.
Lidar calibration experiments 总被引:2,自引:0,他引:2
Hans E. Jørgensen Torben Mikkelsen Jürgen Streicher Hartmut Herrmann Christian Werner Erik Lyck 《Applied physics. B, Lasers and optics》1997,64(3):355-361
A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate
an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost)
identical mini-lidar systems for aerosol cloud detection to test the reproducibility and uncertainty of lidars. Lidar data
were obtained from both single-ended and double-ended lidar configurations. A backstop was introduced in one of the experiments
and a new method was developed where information obtained from the backstop can be used in the inversion algorithm. Independent
in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including
measurements from both sides of a plume. The correspondence with in-situ measurements is excellent. Finally, the new backstop
method is able to reveal information which can close the lidar equation by obtaining the relation between backscatter and
extinction in an aerosol cloud.
Received: 21 December 1995 / Revised version: 25 July 1996 相似文献
99.
E. Vigezzi T. Døssing M. Matsuo K. Yoshida P. Bosetti A. Bracco S. Frattini B. Herskind S. Leoni 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(2):207-211
We present shell model calculations for warm rotating nuclei, combining the cranked Nilsson mean field and a residual surface-delta two-body interaction. The model is used to describe the transition from the region of well-defined rotational bands into the region dominated by rotational damping, and the results are in overall agreement with the experimental findings. 相似文献
100.
Motivated by problems occurring in the empirical identification and modelling of a n-dimensional ARMA time series X(t) we study the possibility of obtaining a factorization (I + a1B + … + apBp) X(t) = [Πi=1p (I ? αiB)] X(t), where B is the backward shift operator. Using a result in [3] we conclude that as in the univariate case such a factorization always exists, but unlike the univariate case in general the factorization is not unique for given a1, a2,…, ap. In fact the number of possibilities is limited upwards by , there being cases, however, where this maximum is not reached. Implications for the existence and possible use of transformations which removes nonstationarity (or almost nonstationarity) of X(t) are mentioned. 相似文献