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排序方式: 共有1114条查询结果,搜索用时 46 毫秒
991.
992.
Ryo Nojima Hideki Imai Kazukuni Kobara Kirill Morozov 《Designs, Codes and Cryptography》2008,49(1-3):289-305
In this paper, we formally prove that padding the plaintext with a random bit-string provides the semantic security against chosen plaintext attack (IND-CPA) for the McEliece (and its dual, the Niederreiter) cryptosystems under the standard assumptions. Such padding has recently been used by Suzuki, Kobara and Imai in the context of RFID security. Our proof relies on the technical result by Katz and Shin from Eurocrypt ’05 showing “pseudorandomness” implied by the learning parity with noise (LPN) problem. We do not need the random oracles as opposed to the known generic constructions which, on the other hand, provide a stronger protection as compared to our scheme—against (adaptive) chosen ciphertext attack, i.e., IND-CCA(2). In order to show that the padded version of the cryptosystem remains practical, we provide some estimates for suitable key sizes together with corresponding workload required for successful attack. 相似文献
993.
Nobumasa Koyama Ryo Watanabe Takayuki Ishida Takashi Nogami Tamizo Kogane 《Polyhedron》2009,28(9-10):2001-2009
Eight kinds of imidazolate-bridged copper(II) complexes were found to be classified into two categories from the magnetic properties. The crystal structures of [Cu(L)(μ-im)]n (Him = imidazole; L = nonane-4,6-dionate, 2,6-dimethylheptane-3,5-dionate) and [Cu(L)(μ-im)]4 (L = nonane-4,6-dionate, 1-phenylbutane-1,3-dionate) were determined, to reveal that they consist of polymeric chains and tetranuclear cycles, respectively. Note that the nonane-4,6-dionate derivative gave the two phases. The Bonner–Fisher model (a one-dimensional antiferromagnetic chain model) was plausibly applied to [Cu(L)(μ-im)]n for the best fit, while a square model was to [Cu(L)(μ-im)]4. The complexes with unknown crystal structures were also subjected to magnetic measurements, and the tetra- and polymeric structures could be clearly distinguished from each other by fitting the magnetic data to appropriate models. The exchange parameters were comparable for both series (2J/kB = ?78 to ?97 K) because the structurally common bridges Cu–N(eq)–N(eq)–Cu afford comparable magnitudes of couplings. 相似文献
994.
Ryo Takahashi 《Proceedings of the American Mathematical Society》2007,135(11):3461-3464
In this note, we characterize finite modules locally of finite injective dimension over commutative Noetherian rings in terms of vanishing of Ext modules.
995.
Ryo Tamaki Yuko Arai Daisuke Ichikawa Masaya Inoue Hideyuki Kunugita Kazuhiro Ema 《Journal of luminescence》2008,128(5-6):842-844
Exciton polariton in an organic–inorganic multiple-quantum-well (MQW) single crystal (C4H9NH3)2PbBr4 at low temperature has been investigated by photoluminescence excitation (PLE), reflection, and time-resolved photoluminescence measurements. Since (C4H9NH3)2PbBr4 has ideal two-dimensional excitons with an extremely large oscillator strength and forms self-organized MQW with a very short well-period (d~10 Å), polaritonic coupling among excitons is strong and extends over a large number of wells. Therefore, observed MQW polariton features were the same as those of bulk polaritons. We have also investigated relaxation dynamics of the MQW polariton in the same framework as discussions on bulk polaritons. 相似文献
996.
Single crystals of dysprosium-doped gadolinium orthovanadate (Dy:GdVO4) were successfully grown by the floating zone method and their fluorescence properties were investigated. The as-grown crystals did not contain any macroscopic defects such as cracks and inclusions for any Dy-concentration of up to 4 at%. Every crystal showed optical homogeneity under observation with a polarizing microscope; that is, no low-angle grain boundaries and growth striations were detected. In the visible region, two distinct fluorescence bands were observed around 480 and 575 nm, corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. The excitation spectrum for the emission of 573 nm indicates the possibility to use a commercially available laser diode of 450 nm as a pumping source for solid-state yellow laser. 相似文献
997.
Makina Saito Ryo Mashita Hiroyuki Kishimoto Ryo Masuda Yoshitaka Yoda Makoto Seto 《Hyperfine Interactions》2017,238(1):99
Tyre rubber has been continuously developed to improve its performance, but the microscopic mechanisms behind these improvements, e.g. by adding nanoparticles to the rubber, are still not fully understood. We study the microscopic polymer dynamics of a rubber nanocomposite system consisting of polymer polybutadiene with 20 volume% of silica nanoparticles with diameters of 100 nm via quasi-elastic scattering experiments using gamma-ray time-domain interferometry. The result shows that the presence of silica nanoparticles caused the inter-chain α-relaxation dynamics to slow down in a shallowly supercooled state suggesting that the presence of the nanoparticles that came in contact with the polymer controlled the timescale of the polymer’s α-relaxation dynamics. Conversely, the presence of nanoparticles less affects the dynamics in a lower temperature region near T g. It is consistent with the result of the differential scanning calorimetry study showing negligible T g difference among the pure polymer and the nanocomposite system. It also shows that the quasi-elastic scattering experiment can be used to reveal the polymer dynamics in nanocomposites and is appropriate for characterising their microscopic dynamics for the purpose of improving tyre performance. 相似文献
998.
Ko Mibu Kazuaki Mikami Masaaki Tanaka Ryo Masuda Yoshitaka Yoda Makoto Seto 《Hyperfine Interactions》2017,238(1):92
The Morin transition of very thin Ir-doped α-Fe2O3 films, which is not detectable with conventional magnetization measurements, was studied by conversion electron Mössbauer spectroscopy using a 57Co source and nuclear resonant scattering using a synchrotron light source. It was found that (i) the Morin transition temperature increases as the Ir ratio increases, (ii) it decreases when the film thickness decreases, and (iii) the transition becomes irreversible when Ir ratio is small and the thickness is thin. These tendencies were found reproducible and systematic, although the mechanisms are to be clarified by further studies. 相似文献
999.
Minoru Maruyama Ryo Matsubayashi Hiroaki Iwakuro Seiji Isoda Teruo Komatsu 《Applied Physics A: Materials Science & Processing》2008,93(2):467-470
We propose a lead-free silver paste as a replacement for a high-temperature lead-rich solder used for electronics. The pastes
tested here contain a small amount of solvent, but primarily consist of silver powder and alkoxide-passivated silver nanoparticles
that undergo nanosintering when heated. The pastes were used to connect silicon diode chips to copper bases at 350°C in nitrogen
ambient without external pressure. The resulting diode packages had electrical and thermal properties about equal to those
with lead-solder joints. The mechanical strengths also were comparable to the lead joint. These properties make this nanosilver
paste the first viable lead-free alternative to a lead solder. 相似文献
1000.
Ryo Yasuhara Toshiyuki Kawashima Takashi Sekine Takashi Kurita Tadashi Ikegawa Osamu Matsumoto Masahiro Miyamoto Hirofumi Kan Hidetsugu Yoshida Junji Kawanaka Masahiro Nakatsuka Noriaki Miyanaga Yasukazu Izawa Tadashi Kanabe 《Optics letters》2008,33(15):1711-1713
We report a high-average-power and high-pulse-energy diode-pumped Nd:glass laser amplifier system consisting of two thermally-edge-controlled zigzag slab amplifiers and a stimulated Brillouin scattering mirror. This phase-conjugated system produces an average power of 213 W at 10 Hz in a 8.9 ns pulse (2.4 GW peak power) with an optical-to-optical conversion efficiency of 11.7% and a near-diffraction-limited beam. To the best of our knowledge, this is the highest performance from a Nd:glass-based laser amplifier system ever built. 相似文献