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1.
Khandelia M. Bambha N.K. Bhattacharyya S.S. 《Signal Processing, IEEE Transactions on》2006,54(2):556-569
This paper explores the problem of efficiently ordering interprocessor communication (IPC) operations in statically scheduled multiprocessors for iterative dataflow graphs. In most digital signal processing (DSP) applications, the throughput of the system is significantly affected by communication costs. By explicitly modeling these costs within an effective graph-theoretic analysis framework, we show that ordered transaction schedules can significantly outperform self-timed schedules even when synchronization costs are low. However, we also show that when communication latencies are nonnegligible, finding an optimal transaction order given a static schedule is an NP-complete problem, and that this intractability holds both under iterative and noniterative execution. We develop new heuristics for finding efficient transaction orders, and perform an extensive experimental comparison to gauge the performance of these heuristics. 相似文献
2.
B. Saha S. Bhattacharyya T. K. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》2003,92(5):413-418
In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H? to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献
3.
Europium (Eu+) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu+ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal
was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal
amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions.
The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both
experimentally and theoretically. 相似文献
4.
An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed 相似文献
5.
6.
Analysis of a part of the meteorite which fell at Dergaon (India) on March 2, 16.40 local time (2001) is presented with the
help of FTIR, absorption and atomic spectra. The FTIR spectrum exhibits prominent absorption bands in the region 800–1100
cm−1, originating from the valence vibration of SiO4, a basic component of the silicate lattice. 相似文献
7.
We present a modular technique for analyzing probe-fed, multilayered microstrip phased-array antennas. Each patch layer is assumed to be infinite in extent and represented by its generalized scattering matrix (GSM) with respect to a finite number of Floquet modes. For multilayer patch analysis, the individual GSMs are combined appropriately to yield the overall GSM of the structure. The individual GSM are obtained using the Galerkin method. The probe layer is represented by its generalized impedance matrix (GIM) which is deduced using Floquet modal analysis and the variational method. The GSMs and GIM are combined appropriately to yield the input impedance seen by the probe. Numerical results computed with this technique are shown to agree favorably with available data. Results for two-layered patch arrays and capacitively coupled patches are also presented 相似文献
8.
P. K. Sinhamahapatra S. K. Bhattacharyya 《Journal of Thermal Analysis and Calorimetry》1979,15(2):233-249
Physicochemical properties of bismuth vanadate catalysts with varying compositions, e.g., Bi4V6O21-6 1/2H2O·1
2
1
NH3; Bi6V2O14·3 H2O; Bi6V4O19·6 H2O have been studied by chemical analysis, differential thermal analysis, thermogravimetry, infrared, X-ray diffraction, surface area and magnetic susceptibility techniques.The endotherms, in all the cases, prior to exo ones are due to stepwise dehydration and those following exochanges are due to decomposition of adsorbed impurities, sintering and melting, etc. The last endopeak, in all the cases, however is due to melting. The exochanges are attributed to stepwise phase transitions. The V-0 stretching in all the compounds is characteristic of polyvanadates. Two types of vanadium-oxygen bonds e.g., V=O and V-O -V are characterized by IR analysis. The fresh first and third vanadates are amorphous whereas the second one is crystalline. The exochanges (presumably due to disorder-order transitions) are suggested to be related to displacement of oxygen anions. The precipitated vanadates are similar with their corresponding solid state reaction products of Bi2O3 and V2O5 when they are heated at elevated temperature. The fresh as well as treated vanadates are diamagnetic. These systems display maximum surface area at the temperature corresponding to complete dehydration. The composition of the precipitated vanadates is not ultimately defined by Bi/V ratio and the binary compound consequently formed.
Zusammenfassung Die physikalisch-chemischen Eigenschaften von Bismuthvanadat-Katalysatoren verschiedener Zusammensetzung, z.B. Bi4V6O21·6 2 1 H2O·1 2 1 NH3; Bi6V2O14·3 H2O; Bi6V4O19·6 H2O wurden durch chemische Analyse, Differentialthermoanalyse, Thermogravimetrie, Infrarot, Röntgendiffraktion, Oberflächenmessung und magnetische Susceptibilitätsmessung untersucht. In jedem Fall werden die den Exo-Änderungen vorangehenden Endo-Änderungen durch stufenweise Dehydratisierung verursacht und diejenigen, welche den Exo-Änderungen folgen, durch Zersetzung adsorbierter Verunreinigungen, Sinterung und Schmelzen. Der letzte Endopeak ist jedoch in jedem Falle dem Schmelzen zuzuschreiben. Die Exo-Änderungen werden stufenweisen Phasenübergängen zugeschrieben. In allen Verbindungen ist die V-O Dehnung für die Polyvanadate charakteristisch. Zwei Typen von Vanadium-Sauerstoff Bindungen, z. B. V=O und V-O-V wurden durch IR-Analyse charakterisiert. Die frisch synthetisierten ersten und dritten Vanadate sind amorph, während das zweite kristallin ist. Die (vermutlich durch Unordnung-Ordnungs Übergänge verursachten) Exo-Änderungen sind wahrscheinlich mit der Bewegung der Sauerstoff-Anionen verbunden. Die gefällten Vanadate sind — wenn sie auf hohe Temperaturen erhitzt werden — ihren entsprechenden Festphasen-Reaktionsprodukten Bi2O3 und V2O5 ähnlich. Die ursprünglichen wie die behandelten Vanadate sind diamagnetisch. Diese Systeme weisen die maximale Oberfläche bei der ihrer vollständigen Dehydratisierung entsprechenden Temperature auf. Die Zusammensetzung der gefällten Vanadate wird letzten Endes nicht durch. ihr Bi-V-Verhältnis und die in der Folge entstandene Binärverbindung bestimmt.
Résumé Les propriétés physico-chimiques des catalyseurs au vanadate de bismuth, de diverses compositions, par ex. Bi4V6O21 · 6 2 1 H2O · 1 2 1 NH3,Bi6V2Oi14 · 3H2O, Bi6V4O19 · 6H2O, ont été étudiées par analyse chimique, analyse thermique différentielle, thermogravimétrie, spectroscopie infrarouge, diffraction des rayons X, mesures de surfaces spécifiques et de susceptibilité magnétique.Dans tous les cas, les phénomènes endothermiques qui précèdent ceux de nature exothermique sont dus à la déshydratation par étapes; les phénomènes endothermiques qui suivent ceux de nature exothermique sont dus aux impuretés adsorbées, au frittage, à la fusion, etc ... Cependant, le dernier pic endothermique est toujours dû à la fusion. Les changements exothermiques sont attribués à des transitions de phases par étapes. La déformation V-0 dans tous les composés est caractéristique des polyvanadates. Deux types de liaisons vanadium-oxygène, par ex. V=O et V-O-V ont été caractérisés par analyse infrarouge. Le premier et le troisième vanadate, fraîchement préparés, sont amorphes alors que le second est cristallisé. Les. phénomènes exothermiques (probablement dus à des transitions désordre-ordre) sont sans doute en rapport avec le déplacement des anions oxygène. Les vanadates précipités — si on les. chauffe jusqu'à une température élevée — sont similaires aux produits correspondants, obtenus par réaction à l'état solide entre Bi2O3 et V2O5. Les vanadates fraîchement préparés ainsi que ceux qui ont subi un traitement thermique, sont diamagnétiques. Ces systèmesmontrent une surface spécifique maximalé à la température correspondant à la déshydratation complète. La composition des vanadates précipités n'est pas finalement définie par le rapport Bi/V et le composé binaire formé par la suite.
- - , , Bi4V6O21 · 6.5 2 ·1.5 NH3; Bi6V2O14 · 2; Bi6V4O19· 6H2O , , , , - , . , , , , , . . . . V- . - : V= V--V. , — . , (-, -) . , Bi2O3 V2O5 . , . , . Bi/V, a, , .相似文献
9.
Kalyan Kumar Das D. Mukherjee S. P. Bhattacharyya 《International journal of quantum chemistry》1986,29(6):1745-1754
Structural features of a series of tetraatomic carbonyls in the 1,3nπ* states are studied by using a recently proposed MCSCF algorithm at the INDO/2 level. The computed geometrical parameters and the inversion barrier heights agree quite well with the available experimental or ab initio theoretical data. The calculated transition energies turn out to be somewhat lower than the experimental counterparts. The specific MCSCF algorithm used is found to have excellent convergence properties. 相似文献
10.
A solution of [ReOCl3(PPh3)2] in benzene reacts with solid (NH4)2WS4, in the presence of traces of H2O, to give [ReOCl(WS4)2]2–, isolated as its PPh4 (1) and NEt4 (2) salts. Both (1) and (2) exhibit (Re=O) at ca. 930, (Re=Cl) at ca. 330 (W=S)t at ca. 495 and (W–S–Re) bridging vibration at ca. 460cm–1. The FAB mass spectrum of (1) shows a peak for [ReO(WS4)2]+(m/z=826 amu) in the positive mode and that for PPh4[ReOCl(WS4)]– (m/z=889amu) in the negative mode, confirming the suggested composition. This is the second example of a d2 metal ion forming a tetrathiometalate complex and also the first example of an oxometal ion (excepting those of W and Mo) forming a molecular complex with tetrathio- tungstate or -molybdate ligands. 相似文献