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81.
M. Gorska H. Grawe D. Foltescu D. B. Fossan R. Grzywacz J. Heese K. H. Maier M. Rejmund H. Roth R. Schubart Ö. Skeppstedt K. Spohr 《Zeitschrift für Physik A Hadrons and Nuclei》1995,353(3):233-234
The neutron deficient nucleus94Pd was identified and studied for the first time by in-beam spectroscopy. An I=(14+) isomer with t1/2=0.8 (2) s was observed in a recoil catcher setup inside the multi-detector -array OSIRIS. Filter detectors for neutrons and charged particles were used to identify the (2p2n) exit channel of the reaction58Ni+40Ca, populated with only 0.06% of the total evaporation residue cross section. The structure of the isomer is discussed within the frame work of shell model calculations in the (p1/2,g9/2) model space with emphasis on the g
9
2/2
T=0, I=1,9 pairing two-body matrix elements.Communicated by: D. Schwalm 相似文献
82.
The quantum density of states of the Henon-Heiles potential displays a pronounced beating pattern. This has been explained by the interference of three isolated classical periodic orbits with nearby actions and periods. A singular magnetic flux line, passing through the origin, drastically alters the beats even though the classical Lagrangian equations of motion remain unchanged. Some of the changes can be easily understood in terms of the Aharonov-Bohm effect. However, we find that the standard periodic orbit theory does not reproduce the diffraction-like quantum effects on those classical orbits which intersect the singular flux line, and argue that corrections of relative order variant Planck's over 2pi are necessary to describe these effects. We also discuss the changes in the distribution of nearest-neighbor spacings in the eigenvalue spectrum, brought about by the flux line. (c) 1995 American Institute of Physics. 相似文献
83.
B. Aspacher W. Frank P. Kizler K. Maier 《Applied Physics A: Materials Science & Processing》1994,59(4):339-348
In previous Perturbed-Angular-Correlation (PAC) studies of the - emission of 111In probe nuclei in cold-worked or particle-irradiated nickel, it has been found that thermal annealing in the temperature regime of recovery stage III leads to the formation of so-called C-defects (Cubic defects). This is indicated by the occurrence of a new frequency of about 80 Mrad/s, in addition to the frequency (200 Mrad/s) that is due to 111In on substitutional sites. Obviously, the C-defects are complexes consisting of 111In and the intrinsic point-defect species that migrates freely in recovery stage III. Therefore, they have played an important rôle in the long-standing controversy on whether the recovery-stage-III defects are vacancies (one-interstitial model) or self-interstitials (two-interstitial model). The present paper reports on a novel experimental effort to reveal the nature of the C-defects by combining PAC studies on nickel samples differently pretreated in a systematic way, investigations of the Extended X-ray Absorption Fine Structure (EXAFS) on In-doped nickel, and measurements of the decay rate of 111In nuclei in the Electron-Capture-Induced Decay (ECID). On the basis of the results of these experiments it is concluded that the defects trapped by substitutional 111In atoms (Ins) in recovery stage III are self-interstitials (I), as expected according to the two-interstitial model. Moreover, there is evidence that the C-defects are In interstitials on tetrahedral sites (Ini) that form exclusively in the vicinity of the specimen surface from Ins – I pairs via the reaction Ins+I Ini. 相似文献
84.
85.
Moll AE Heimburger R Lagarde F Leroy MJ Maier E 《Analytical and bioanalytical chemistry》1996,354(5-6):550-556
An analytical procedure for total arsenic and arsenic species quantification in marine organisms has been developed. Fresh materials are freeze-dried and reduced to powders before analysis. Arsenic is determined either by energy dispersive X-ray fluorescence (EDXRF) directly or by inductively coupled plasma optical emission spectrometry (ICP/OES) after microwave digestion. Arsenic speciation is performed on the extracted sample using liquid chromatography coupled to ICP/OES for arsenobetaine and arsenocholine determination and to the hydride generation-quartz furnace atomic absorption spectrometric technique for arsenite, arsenate, monomethylarsonic and dimethylarsinic acids quantification. Special precautions are taken to avoid losses or contaminations as well as to prevent analytical errors during the quantification stage. Other methods are applied and the corresponding results compared for each step of the procedure. The method is finally validated by means of intercomparison studies within the Measurements and Testing Programme of the European Community (formely BCR). 相似文献
86.
87.
Franck-Condon factor distributions for bound-to-continuum transitions of one-dimensional vibrational states are calculated
by a) using numerical integration, b) employing a finite number of square integrable harmonic oscillator functions. The methods
are generally applicable to any kind of bound or repulsive potential involved. Results are presented and compared to model
potential calculations previously reported by Krüger [1]. 相似文献
88.
Polyol Metal Complexes. 25. rac-Mannose, rac-Arabitol and L -Threitol as Deprotonated Ligands in Ferrates(III ) Ba2[Fe2(β-rac-ManfH?5)2] · 12H2O ( 1 ), Sr4[Fe4(rac-Arab1,2,3,5H?4)4(OH)2]CO3 · 33 H2O ( 2 ), and Ba2[Fe2(L-ThreH?4)2(OH)2] · 12.5 H2O ( 3 ) (Man = mannose, Arab = arabitol, Thre = threitol) have been crystallized from alkaline aqueous solution. Crystal structure analysis revealed dinuclear ferrate(III ) ions for 1 and 3 , the former being a Ci-symmetrical homoleptic ferric complex with pentadentate pentaanions derived from racemic β-mannofuranose. In 3 , besides tetradentate L -threitolato ligands, there is one terminal hydroxo ligand at each ferric center. Hydroxo ligands are also present in the Ci-symmetrical hexaanions of 2 , which are tetranuclear planar entities built up from four edge-sharing FeO6 octahedra. However arabitol is a pentitol, the tetraanionic ligands are only tetradentate for steric reasons. 相似文献
89.
The reaction of acetone-4-chlorophenylhydrazone (6) with bromine in the presence of acetamide yields 2-bromo-2-(4-chlorophenylazo)-propane (7) and 2,2-bis(4-chlorophenylazo)propane (8). The unstable heteroallylic bromide7 was subjected without isolation to nucleophilic displacements with a series of heteronucleophiles thereby affording the corresponding 2-(4-chlorophenylazo)-2-propane derivatives9 with the azo- and heteroelement-functions in a geminal position to each other.
Herrn Prof. Dr. Dr. h. c.K. Kratzl mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献
90.
Under O2, the Aspidosperma alkaloid tabersonine ( 1 ) was converted by a crude enzyme preparation from leaves of mature plants of Catharanthus roseus G DON into the trimeric 3-hydroxy-14′-(3α″-tabersonyl)voafrine B ( 4 ) which was easily reduced by NaBH4 to 14′-(3α″-tabersonyl)voafrine B ( = tertabersonine; 5 ). Compounds such as 4 and 5 are the first trimeric alkaloids in the series of monoterpenoid indole alkaloids. 相似文献