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141.
Photoinduced charge separation in donor–acceptor conjugates plays a pivotal role in technology breakthroughs, especially in the areas of efficient conversion of solar energy into electrical energy and fuels. Extending the lifetime of the charge separated species is a necessity for their practical utilization, and this is often achieved by following the mechanism of natural photosynthesis where the process of electron/hole migration occurs distantly separating the radical ion pairs. Here, we hypothesize and demonstrate a new mechanism to stabilize the charge separated states via the process of electron exchange among the different acceptor entities in multimodular donor–acceptor conjugates. For this, star-shaped, central triphenylamine derived, dimethylamine–tetracyanobutadiene conjugates have been newly designed and characterized. Electron exchange was witnessed upon electroreduction in conjugates having multiple numbers of electron acceptors. Using ultrafast spectroscopy, the occurrence of excited state charge separation, and the effect of electron exchange in prolonging the lifetime of charge separated states in the conjugates having multiple acceptors have been successfully demonstrated. This work constitutes the first example of stabilizing charge-separated states via the process of electron exchange.The significance of electron exchange in stabilizing the charge-separated state is revealed in multi-modular donor–acceptor conjugates. 相似文献
142.
Summary A short stainless steel column packed with silica gel is cooled to –78°C and atmospheric hydrocarbons are preconcentrated from 3 I of air on it. Desorption to the analytical column is by heating for 10 min to 200°C. Analysis is by GC on OPN-Poracil C at 27°C. The sorption efficiencies were nearly 100% for most of the light hydrocarbons. 相似文献
143.
M. Chandra Sekhar P. Kondaiah S.V. Jagadeesh Chandra G. Mohan Rao S. Uthanna 《Applied Surface Science》2011,258(5):1789
Titanium dioxide (TiO2) films have been deposited on glass and p-silicon (1 0 0) substrates by DC magnetron sputtering technique to investigate their structural, electrical and optical properties. The surface composition of the TiO2 films has been analyzed by X-ray photoelectron spectroscopy. The TiO2 films formed on unbiased substrates were amorphous. Application of negative bias voltage to the substrate transformed the amorphous TiO2 into polycrystalline as confirmed by Raman spectroscopic studies. Thin film capacitors with configuration of Al/TiO2/p-Si have been fabricated. The leakage current density of unbiased films was 1 × 10−6 A/cm2 at a gate bias voltage of 1.5 V and it was decreased to 1.41 × 10−7 A/cm2 with the increase of substrate bias voltage to −150 V owing to the increase in thickness of interfacial layer of SiO2. Dielectric properties and AC electrical conductivity of the films were studied at various frequencies for unbiased and biased at −150 V. The capacitance at 1 MHz for unbiased films was 2.42 × 10−10 F and it increased to 5.8 × 10−10 F in the films formed at substrate bias voltage of −150 V. Dielectric constant of TiO2 films were calculated from capacitance–voltage measurements at 1 MHz frequency. The dielectric constant of unbiased films was 6.2 while those formed at −150 V it increased to 19. The optical band gap of the films decreased from 3.50 to 3.42 eV with the increase of substrate bias voltage from 0 to −150 V. 相似文献
144.
D. Mohan Ganga Radhakrishnan S. Rajadurai K. Venkata Rao Gordon G. Cameron 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):2123-2133
Polyacrylamide has been grafted onto casein in phosphate buffer medium using potassium peroxodisulfate as initiator. The influence of synthetic variables on percent grafting, grafting efficiency, rates of conversion of monomer, and the rates of graft copolymerization have been discussed. A possible kinetic scheme based on experimental results has been derived. 相似文献
145.
Rahul Bhatt Sanjay K. Mishra D. Mohan A.K. Gupta 《Optics and Lasers in Engineering》2008,46(6):428-439
A fast holographic wavefront sensor is proposed using a computer-generated hologram (CGH). This CGH is a multiplexed hologram of different Zernike mode–amplitude combinations, and is designed in such a manner as to get the corresponding spots on the detector according to the presence and strength of a particular aberration. Interference between the aberrated wavefront (with a single mode–amplitude combination) and the Fourier transform of an image with single bright pixel (defined as dot image) is numerically calculated for one hologram. Different mode–amplitude combination and corresponding different positions of bright pixels (dots) are taken to compute various holograms and then all the holograms are multiplexed to get the final hologram. When the aberrated wavefront with a particular mode–amplitude combination is incident onto the multiplexed hologram, the corresponding dot is generated in the Fourier plane. A lens performs the Fourier transform in optical domain and provides the instant detection of amplitude of the respective Zernike mode. The main advantage of the scheme is to avoid the need of any computations, which makes it really fast. The simulation results are presented with the cross-talk analysis for few Zernike terms. 相似文献
146.
Mohan D. Deshpande 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1986,37(3):361-373
Summary The Navier-Stokes equations are solved numerically to study the problems of laminar, axisymmetric jet impinging normally on an indented wall. The results obtained for three different wall geometries and Reynolds number range upto 25 are compared with those for the impingement on a plane wall to study the influence of indentation. The overall flow picture remains similar to the plane wall case qualitatively but the wall shear stress and pressure distribution get altered in the indented region.
Zusammenfassung Es wird der Strömungsverlauf eines laminaren achsensymmetrischen Strahles nach dem Aufprall auf eine Wand mit Einbuchtung analysiert. Hierzu wird die numerische Lösung der Navier-Stokeschen Gleichungen benutzt. Die Ergebnisse für drei verschiedene Wandgeometrien, als auch für verschiedene Reynolds-Zahlen bis auf 25, sind mit dem Fall der ebenen Wand verglichen, um hieraus den Einfluß der Einbuchtung festzustellen. Das globale Strömungsbild bleibt in allen Fällen qualitativ ähnlich. Es wurde jedoch festgestellt, daß im Bereich der Einbuchtung die Wandschubspannung sowie die Druckverteilung gewisse Änderungen aufweisen.相似文献
147.
148.
G. Mohan Rao T. S. Panchapagesan S. Mohan 《Applied Physics A: Materials Science & Processing》1990,51(5):423-426
Metal-insulator composites (cermets) find use in a wide range of applications. In this paper the preparation of cermet films by dc reactive magnetron sputtering is presented. These cermets have been characterised by measuring their electrical resistance and the properties have been correlated to the microstructure and composition. Magnetron sputtering is found to be very effective in controlling the composition of the deposited films, enabling the preparation of films with tailored properties. 相似文献
149.
Subhash P. Chavan Mahesh Thakkar Ashok B. Pathak Mohan M. Bhadbhade 《Tetrahedron》2005,61(15):3873-3879
The first enantiospecific synthesis of (+)-β-herbertenol, from naturally occurring R-(+)-citronellal, employing Taber's diazo decomposition protocol as the key step, is described. 相似文献
150.
Carbon nanotubes have been grown using an electron cyclotron resonance (ECR) plasma source at a substrate temperature of 500 °C. Methane has been used as the source gas. A network of carbon nanotubes has been observed in scanning electron microscopy. Transmission electron microscopy revealed that the structure consists of straight, Y-junction and ring-like nanotubes. Further, electron diffraction of the nanotubes confirms a graphite crystal structure. PACS 81.16.He; 68.37.Lp; 68.37.Hk; 85.35.Kt; 75.75.+a 相似文献