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991.
Kılıç Önder Belivermiş Murat Sıkdokur Ercan Sezer Narin Akyıl Erentürk Sema Haciyakupoglu Sevilay Madadzada Afag Frontasyeva Marina 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):699-706
Journal of Radioanalytical and Nuclear Chemistry - This study presents the first data of 210Po and 210Pb activity concentrations using moss species Hypnum cupressiforme from Thrace region, the... 相似文献
992.
Dr. Özgün Attila Dr. Helen E. King Dr. Florian Meirer Prof. Dr. Bert M. Weckhuysen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(29):7158-7167
Hydrothermal treatment is a common method used to modify the physicochemical properties of zeolite-based catalyst materials. It alters the number and type of acid sites through dealumination and increases molecular diffusion by mesopore formation. Steaming also reduces the structural integrity of zeolite frameworks. In this study, Raman microscopy has been used to map large zeolite ZSM-5 crystals before and after steaming. 3D elemental maps of T−O (T: Al or Si) sites of the zeolite were obtained. The Raman active vibrational bands were determined, which are indicative of (non-) framework Al, as well as of structural integrity. Zeolite steaming caused the introduction of additional heterogeneities within the zeolite framework. Al migration and the formation of extra-framework Al species were observed. The described experiments demonstrate the capability of 3D Raman spectroscopy as a valuable tool to obtain information on the spatial distributions of framework elements as well as defects within a zeolite-based material. 相似文献
993.
Özgür Açık 《General Relativity and Gravitation》2018,50(3):33
We have found two non-trivial massless Dirac and two massive Rarita–Schwinger solutions in plane wave spacetimes. The first order symmetry operator transforming one of the massless Dirac solution to the other is constructed. The only non-vanishing spinor bilinear generated by the standard spinor basis is obtained and algebraic relations between the induced parallel forms are demonstrated. It is also seen that the spin-3/2 norm of the Rarita–Schwinger solutions enforces to the massless sector. 相似文献
994.
Cihan Kürkçü Selgin AL Ziya Merdan Çağatay Yamçiçier Hülya Öztürk 《Chinese Journal of Physics (Taipei)》2018,56(3):783-792
The pressure induced phase transition of β-HgS is studied using an ab initio molecular dynamics simulation. The structural phase transformation from the zinc-blende structure to the NaCl-type structure (space group ) and from this structure to CsCl-type structure () with the application of hydrostatic pressure is predicted. Additionally, the electronic properties of HgS and various physical properties such as the lattice constants, the bulk modulus and the pressure derivative of the bulk modulus are revealed. Furthermore, these phase transitions are obtained using the total energy and enthalpy calculations. According to these calculations these transformations are occurring at about 20?GPa and 28?GPa for → and →, respectively. 相似文献
995.
Selgin Al Nihat Arikan Mustafa Özduran Ahmet İyigör 《Chinese Journal of Physics (Taipei)》2018,56(4):1508-1514
The structural, elastic, electronic and phonon properties of X3Au (X?=?Ti, Zr and V) compounds in the A15 structure were obtained in the framework of the density functional theory (DFT) within the generalized gradient approximation (GGA). The equilibrium lattice constants, bulk modulus and elastic constants were calculated. The calculation of elastic constants revealed that V3Au has the highest hardness nature and incompressibility along the x-axis among them. The computed elastic constants also provided information about the ductility of X3Au compounds which were predicted using Pugh's criteria. The results indicated that all three compounds have ductile nature. The density of states calculations revealed that electrons of Ti, Zr and V provide most contribution to the conductivity of the compounds and thus cause a metallic bonding. The investigation of stability via phonon spectra of compounds showed that these compounds are dynamically stable in the A15 structure. 相似文献
996.
Within a spontaneously broken color gauge theory of integer charge quarks (icq) one expects standard “confined” QCD predictions for leptoproduction experiments (e.g.,μN→μX) to hold for energies below the threshold for color production; above such a threshold, however, the color degree of freedom must be excited leading to a threshold rise in structure functions. We predict the expected rises for μN and charged current (cc) νN and scattering within the “naive” parton model. Comparing these predictions with the available data on μN, cc νN and as well as e?e+ experiments, we deduce that the lightest spin-parity 1? color octet meson (like the gluon) as well as the lightest color octet (8, 8) baryon must lie above 7–8 GeV. This in turn closes the only window in the light mass region <3.1 GeV (i.e., the 1.1 to 1.8 GeVregion), whichhadsofarbeenleftopenasapossiblevalueforthephysicalmassofthegluon. Wenextobservethatthetrendofthemostrecent high-Q2 high-W Michigan State-Fermilab experiment on μN scattering exhibiting a relatively sharp rise in F2 above the expectations of confined QCD of order 15% at low x agrees very well with our predictions based on the gauge model of icq. This rise, if confirmed, would favor the hypothesis of gauge icq, and simultaneously imply a threshold for the liberated color octet (8, 8) state at nearly (9±0.6) GeV and a mass for the liberated gluon in the region 8 to 9.5 GeV. We remark that within a left-right symmetric gauge structure leading to icq, charged current scattering of laboratory neutrinos (νN→μ?X) will excite color only provided that the charged gluons V+ mix with V-A gauge particles WL+mrather then with the V+A gauge particles WR+. Thus it is possible that the μN, e?e+ and neutral current scattering of neutrinos (i.e., νN→νX) show signs of color excitation, while the charged current scattering of neutrinos does not. We discuss briefly the implications of the threshold for liberated color octet states possibly lying around 8–10 GeV or higher on future e?e+ experiments as well as dilepton-search experiments. 相似文献
997.
A criterion based on the concept of maximum overlap has been used as an optimizing principle to obtain approximate all valence electron wave functions for a variety of molecules. By means of this procedure, the wave functions are obtained without the use of parameters, semiempirical data, or integral approximations. Even though there are obvious errors in such an approach, the charge densities and dipole moments calculated from these wave functions have a surprising degree of validity. It does appear, though, that the results will be most reasonable for strongly covalent molecules, where large amounts of charge migration are not involved.
This work was supported in part by the National Science Foundation, Grant NSF-GP-16666.
IBM Graduate Fellow. 相似文献
Zusammenfassung Ein Kriterium auf Grund der Konzeption der maximalen Überlappung wurde als Optimalisierungsprinzip verwendet, um Wellenfunktionen für alle Valenzelektronen einer ganzen Reihe von Molekülen zu finden. Auf diesem Weg werden keine Parameter, semiempirische Daten oder Integral-näherungen benötigt. Trotz der offensichtlichen Vernachlässigungen sind die erhaltenen Ladungsdichten und Dipolmomente erstaunlich gut. Allerdings scheint es, als ob die Ergebnisse bei ausgeprägt kovalenten Molekülen am besten wären, wo größbere Ladungsverschiebungen nicht auftreten.
Resumé Utilisation d'un critère fondé sur le concept du recouvrement maximum comme principe pour obtenir des fonctions d'onde pour tous les électrons de valence de toute une variété de molécules. A l'aide de ce procédé les fonctions d'onde sont obtenues sans l'emploi de paramètres, de données semi-empiriques ou d'approximation d'intégrales. Quoique cette approche comporte des erreurs évidentes, les densités de charge et les moments dipolaires calculés à partir de ces fonctions d'onde ont un degré de validité surprenant. Il apparaît néanmoins que les résultats seront d'autant plus raisonnables que les molécules seront plus covalentes et ne comporteront pas de transferts de charges importants.
This work was supported in part by the National Science Foundation, Grant NSF-GP-16666.
IBM Graduate Fellow. 相似文献
998.
M. Ördögh S. Fazekas E. Horváth I. Óváry L. Pogány I. L. Sziklai E. Szabó 《Journal of Radioanalytical and Nuclear Chemistry》1983,79(1):15-21
The regional distribution of copper and other trace elements was determined in the brain of a patient deceased in Wilson's disease against a control brain. The heterogeneous distribution of copper was checked by scanning electron microscope equipped with an X-ray microanalyzer. 相似文献
999.
Body movements during sleep and subjective sleep quality, as well as mood and performance were investigated after exposure to intermittent and continuous traffic noise during the night. In a first experiment, six young subjects slept in the laboratory for five nights; in a second experiment 12 subjects slept six consecutive nights in the laboratory. A good dose-response relationship was obtained between intermittent noise and subjective sleep quality: i.e., the higher the noise level, the poorer the sleep quality. A similar dose-response relationship was found for body movements immediately following noise peaks during nights with intermittent noise. Performance and mood tended to be worse after intermittent noise. However, these effects did not increase with an increase in noise levels. Compared with intermittent noise, continuous noise had a significantly smaller effect on sleep quality. Mood and performance were not worse after continuous noise. The results suggest that increased attention should be paid to peak noise levels when standards for nocturnal noise are set. 相似文献
1000.
57Fe Mössbauer spectra recorded in situ in vacuo from chromium- and gallium-doped Fe3O4 at elevated temperatures show the dopant ions to depress the Curie temperature of Fe3O4 by ca. 70 K. Spectra recorded from aluminium-doped -Fe2O3 show the onset of conversion to aluminium-doped -Fe2O3 to begin at ca. 750 K, which is ca. 100 K above the conversion temperature for undoped -Fe2O3. The variation in magnetic hyperfine fields at temperatures exceeding ca. 750 K is similar to that recorded from -Fe2O3 when doped with zinc or magnesium. At temperatures exceeding 900 K the zinc doped -Fe2O3 partially converts to spinel-related ZnFe2O4. 相似文献