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111.
Takayuki Motoyama Toshiaki Hayashi Hiroshi Hirota Masashi Ueki Hiroyuki Osada 《Chemistry & biology》2012,19(12):1611-1619
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112.
We report the first periodic traveling-wave photodetector fabricated by using unitraveling-carrier photodiodes (UTC-PDs). The photodetector comprises three UTC-PDs with a 0.06-μm absorption layer that is periodically arranged along a coplanar waveguide transmission line. The photoresponse of the photodetector is three times larger than that of a single UTC-PD. A photodetector with terminal resistors at the input end achieves a 3-dB bandwidth of 115 GHz at 1.55 μm. This is almost the same value as that for a single UTC-PD. For one without terminal resistors, the 3-dB bandwidth degrades to 56 GHz as a result of the backward-propagating microwave being reflected at the input end. These results suggest that the photodetector is well designed with both velocity and impedance matchings 相似文献
113.
Kenji Sasaki Yasuyoshi Satoh Takashi Hirota Taiji Nakayama Yoshinori Tominaga Raymond N. Castle 《Journal of heterocyclic chemistry》2000,37(4):959-967
Naphtho[1,2‐b][1]benzothiophene‐6‐carboxylic acids, 6H‐benzo[b]naphtho[2,3‐d]thiopyran‐6‐ones and 6H‐benzo[b]naphtho[2,3‐d]pyran‐6‐ones were synthesized in one step by the photocyclization reaction of 3‐aryl‐2‐([1]benzothien‐3‐yl)propenoic acids. The photocyclization reaction did not occur when the 3‐aryl group contained the electron‐withdrawing nitro group. The assignment of the 1H and 13C nmr spectra of 6H‐benzo[b]naphtho[2,3‐d]thiopyran‐6‐one and 6H‐benzo[b]naphtho[2,3‐d]pyran‐6‐one by two‐dimensional nmr methods is described. The difference between the chemical shift values of H12 for these two compounds is attributed to different molecular geometries. 相似文献
114.
The decrease of initiation efficiency (radical entry efficiency) during seeded emulsion copolymerizations of styrene and butyl acrylate with different residual monomer reduction strategies was evaluated. Experiments were carried out using 50 and 99wt.% of styrene in monomer feed stream. Simulations were performed with a detailed mathematical model of the process that takes into account the diffusion control of initiation, propagation and termination. Results showed that the radical entry into polymer particles is strongly influenced by the aqueous phase kinetics and by the monomer solubility in aqueous phase. Simulation results were compared to experimental results of residual monomer and showed that the residual monomer content can be reduced by a temperature increase at the end of the polymerization. However, an additional feeding of more initiator, even when combined with such an increase of temperature, did not lead to a smaller residual monomer content due, mainly, the kinetic of termination in aqueous phase and radical anchoring. A model that accounts for the reduction of initiator efficiency (free radical entry efficiency) was successfully used to explain the behavior of the experimental observations and was able to correctly predict the qualitative trends of the effectiveness of different residual monomer reduction strategies. 相似文献
115.
In this review paper, we first introduce the basic concept of quantum computer-resistant cryptography, which is the cornerstone of security technology for the network of a new era. Then, we will describe the positioning of mathematical cryptography and quantum cryptography, that are currently being researched and developed. Quantum cryptography includes QKD and quantum stream cipher, but we point out that the latter is expected as the core technology of next-generation communication systems. Various ideas have been proposed for QKD quantum cryptography, but most of them use a single-photon or similar signal. Then, although such technologies are applicable to special situations, these methods still have several difficulties to provide functions that surpass conventional technologies for social systems in the real environment. Thus, the quantum stream cipher has come to be expected as one promising countermeasure, which artificially creates quantum properties using special modulation techniques based on the macroscopic coherent state. In addition, it has the possibility to provide superior security performance than one-time pad cipher. Finally, we introduce detailed research activity aimed at putting the quantum stream cipher into practical use in social network technology. 相似文献
116.
Commercial Pd/C catalysts show different catalytic activity toward the deprotection of silyl and THP ethers. The Pd/C purchased from Merck and ACROS exhibits marked tendency to cleave these protective groups unexpectedly without hydrogen conditions although Aldrich's Pd/C (20,569-9) is inactive in the absence of hydrogen. It was proved that the Pd/C disparity toward the deprotection of TES and THP ethers results from residual acids and/or palladium chloride in the production process of Pd/Cs. Although a TES ether cleavage reaction in the absence of hydrogen and a THP ether cleavage reaction in the presence of hydrogen using 10% Pd/C were recently published, we could conclude they were only an acid-catalyzed solvolysis, the acid being released from the catalyst. Hydrogen is essential for the actual 10% Pd/C-catalyzed cleavage of TES ethers and THP ethers which must be stable under the true Pd/C-catalyzed hydrogenation conditions. 相似文献
117.
In response to the Comment of Furi?, attention is drawn to four points: the dinstinction between the reaction and normal coordinates, zero-point energy, an alternative of the NMR results, and ab initio calculations. 相似文献
118.
The dye laser excitation spectrum of the Swan band (v′ ? v″ = 1 ? 0) has been observed with Doppler-limited resolution. The C2 molecule was generated by the reaction of microwave discharge products of CF4 with CH4. The high sensitivity of laser excitation spectroscopy has enabled us to observe not only transitions, but also transitions and to determine molecular constants including the spin-orbit coupling constant for both the d3Πg and a3Πu states. The parameters thus obtained for a3Πu were favorably compared with those previously obtained from the Ballik-Ramsay band. The present results on the d3Πgv = 1 state were combined with those of an earlier Fourier spectroscopic study on the Swan band (v′ ? v″ = 0 ? 0) to derive equilibrium molecular constants for the d3Πg state. The contributions of the spin-rotation interaction and the centrifugal correction for the spin-orbit coupling to the energy levels in a 3Π state have been discussed in detail. 相似文献
119.
A review on the developments of the magnetic-resonance-related spin chemistry in Japan is presented. We describe how studies in this area started in Japan and developed into the flourishing state of the present. Important contributions made by Japanese spin chemists in the last two decades in three areas, namely, work on chemically induced dynamic electron polarization, excited states and controlling of photochemical reactions, are presented. More emphases are placed on the new developments in recent years, particularly new concepts and new methodologies. 相似文献
120.
In order to clarify the dynamical aspects of the peptide structure, N-methylpropionamide (NMPA) was investigated as an example of peptide molecules: XCONHY (X=CH3CH2 and Y=CH3 for NMPA), paying special attention to the internal rotation of the two methyl groups. NMPA was found to have an almost planar skeleton with an extended syn/trans conformation, as indicated by the observed value of Iaa+Ibb−Icc, and its rotational spectra were interpreted in terms of group G18 consisting of six symmetry species: A1, A2, E1, E2, E3, and E4. The A1 and E2 spectra were observed split in most of b-type transitions, yielding the internal-rotation potential barrier V3 of 796 (21) cm−1 for CH3 in the ethyl group referred to as C-CH3. The spectra of the three E species: E1, E3, and E4 appeared several tens to thousands MHz apart from the corresponding A1 spectra, suggesting the internal-rotation potential barrier of CH3 bonded to the nitrogen, called N-CH3, to be quite low. In sharp contrast with the A1 spectra, which were well fitted to the ordinary asymmetric-rotor spectral pattern, a few higher-order terms were required to reproduce the E1 spectra, presumably because of the low N-CH3 barrier. The spectral analysis thus performed, in fact, led to the V3 of 80.06487 (14) cm−1, an order of magnitude lower than that of C-CH3. The E3 and E4 spectra were found to form triplets with the corresponding E1 lines at the center, and the E3-E1 and E4-E1 splittings were explained essentially by the contributions of the C-CH3 internal rotation combined with the kinetic-energy coupling between the two methyl groups. The torsion around the C-C bond between the ethyl and carbonyl groups was suggested by an ab initio calculation to be of double minimum nature, but the observed A1 spectra did not show any indication of such a double-minimum potential for the C-C torsion, although the possibility of a small hump being present at a planar conformation could not be entirely eliminated. The present results on NMPA along with those obtained on other peptide molecules will be of some significance in clarifying important problems of structural biology such as protein folding and signal transfer through biological systems. 相似文献