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991.
Kaoru Taketani Kenji Mishima Takashi Ino Tamaki Yoshioka Suguru Muto Takahiro Morishima Hirohiko M. Shimizu Takayuki Oku Junichi Suzuki Takenao Shinohara Kenji Sakai Hiromi Sato Katsuya Hirota Yoshie Otake Masaaki Kitaguchi Masahiro Hino Yoshichika Seki Yoshihisa Iwashita Masako Yamada Masahiro Ichikawa Takanori Sugimoto Shinsuke Kawasaki Sachio Komamiya Yoshio Kamiya Hidetoshi Otono Satoru Yamashita Peter Geltenbort 《Physica B: Condensed Matter》2009,404(17):2643-2645
We obtained highly polarized very cold neutrons through a quadrupole magnet with a large aperture. When neutrons go through a quadrupole magnet, parallel-spin neutrons are attracted to the magnet axis and anti-parallel-spin neutrons are repelled off the axis. Therefore, the neutrons through a sufficiently long quadrupole magnet have completely parallel-spin. At the downstream of the quadrupole magnet, we placed another quadrupole magnet to divide neutrons into two regions depending on their spin directions. We obtained the neutron polarization from the integrated count of the two regions and found it was 99.88±0.09 (stat.)±0.05 (syst.)%. 相似文献
992.
The domain formation process of the photo-induced cooperative low-spin (LS) to high-spin (HS) conversion phenomena are studied based on the Monte Carlo simulation method. The existence of the threshold light intensity and the incubation period are demonstrated. It is pointed out that the nucleation barrier of HS domain is surmounted by the fluctuation caused by the repetition of excitation and de-excitation. By defining an effective temperature for this fluctuation, the time scale of incubation period is estimated following the usual domain formation theory. It grossly accounts the Monte Carlo (MC) results in three-dimensional cases. The phase separation of HS and LS domain is reproduced by considering the volume striction effect. The step wise abrupt conversion is ascribed to the de-pinning of the volume striction. 相似文献
993.
Ryosuke Matsuoka Tatsuto Yui Ryo Sasai Katsuhiko Takagi Haruo Inoue 《Molecular Crystals and Liquid Crystals》2013,570(2):333-338
Abstract Tetra-(4-sulfonatophenyl)porphyrinatotin(IV) aggregated efficiently in a clay (saponite) layer intercalated with a polyfluorinated surfactant, but no aggregation was observed in a hydrocarbon type surfactant-clay hybrid environment. Germanium(IV) porphyrins remained as monomers even in the polyfluorinated environment. 相似文献
994.
Toshifumi Satoh Masaki Tamaki Tsukasa Taguchi Hideki Misaka Nguyen To Hoai Ryosuke Sakai Toyoji Kakuchi 《Journal of polymer science. Part A, Polymer chemistry》2011,49(11):2353-2365
The cationic ring‐opening multibranching polymerization of 2‐hydroxymethyloxetane ( 1 ) as a novel latent AB2‐type monomer was carried out using trifluoromethane sulfonic acid or trifluoroboron diethyl etherate by a slow‐monomer‐addition (SMA) method. The polymer yield of poly‐1 ranged from ca. 58–88%, which increase with the increasing monomer addition time on the SMA method. The absolute molecular weights (Mw,MALLS) and the polydispersities of poly‐1 were in the range of 8,000–43,500 and 1.45–4.53, respectively, which also increased with the increasing monomer addition time. The Mark‐Houwink‐Sakurada exponents α in 0.2 M NaNO3 aq. were determined to be 0.02–0.25 for poly‐1 , indicating that poly‐1 has compact forms in the solution because of the highly branched structure. The degree of the branching value of poly‐1 , which was calculated by Frey's equation, ranged from ca. 0.50 to 0.58, which increased with the increasing monomer addition time. The steady shear flow of poly‐1 in aqueous solution exhibited a Newtonian behavior with steady shear viscosities independent of the shear rate. The results of the MALLS, NMR, and viscosity measurements indicated that poly‐1 is composed of a highly branched structure, i.e., the hyperbranched poly (2‐hydroxymethyloxetane). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
995.
996.
997.
Seiji Sakai Seiji Mitani Yoshihiro Matsumoto Shiro Entani Pavel Avramov Manabu Ohtomo Hiroshi Naramoto Koki Takanashi 《Journal of magnetism and magnetic materials》2012
Voltage-dependence of the tunneling magnetoresistance effect in the granular C60–Co films has been investigated for the samples with the current-perpendicular-to-plane geometry. The transport measurements under this geometry demonstrate that the granular C60–Co films show an unusual exponential bias voltage dependence of the magnetoresistance ratio down to zero voltage. Small characteristic energies of less than 10's meV are derived from the temperature dependences of the characteristic voltage in the exponential relationship. Considering the magnitudes of the voltage drop between Co nanoparticles and also the effect of cotunneling on the energy values, the characteristic energies for the voltage-induced degradation of the spin polarization are found to show a satisfactory agreement with that for the thermally-induced one. It can be reasonably expected that the onset of magnetic disorder to the localized d-electron spins at the interface region of the C60-based matrix (C60–Co compound) with Co nanoparticles leading to the unusual voltage and temperature dependence of the magnetoresistance ratio and the spin polarization at low temperatures. 相似文献
998.
Dr. Miguel Paraja Dr. Andrea Gini Dr. Naomi Sakai Prof. Stefan Matile 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15471-15476
Pnictogen-bonding catalysis and supramolecular σ-hole catalysis in general is currently being introduced as the non-covalent counterpart of covalent Lewis acid catalysis. With access to anti-Baldwin cyclizations identified as unique characteristic, pnictogen-bonding catalysis appeared promising to elucidate one of the hidden enigmas of brevetoxin-type epoxide opening polyether cascade cyclizations, that is the cyclization of certain trans epoxides into cis-fused rings. In principle, a shift from SN2- to SN1-type mechanisms could suffice to rationalize this inversion of configuration. However, the same inversion could be explained by a completely different mechanism: Ring opening with C−C bond cleavage into a branched hydroxy-5-enal and the corresponding cyclic hemiacetal, followed by cascade cyclization under conformational control, including stereoselective C−C bond formation. In this report, a pnictogen-bonding supramolecular SbV catalyst is used to demonstrate that this unorthodox polyether cascade cyclization mechanism occurs. 相似文献
999.
Masataka Sugimoto Keisuke Sakai Yuji Aoki Takashi Taniguchi Kiyohito Koyama Toshihiro Ueda 《Journal of Polymer Science.Polymer Physics》2009,47(10):955-965
The effect of hydrocarbon oil incorporation on the rheological and phase behaviors of poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) has been investigated. SEBS‐A1 (neat SEBS) shows a presence of very long relaxation time mode even at the highest temperature carried out here. On the other hand, G′ of SEBS‐A3 (oil concentration = 50 wt %) drastically decreases with increase of temperature at a critical temperature, which can be assigned to be order–disorder transition (ODT). The critical temperature was determined by two rheological criteria. Incorporation of hydrocarbon oil affects the ODT temperature. The rheological response is very sensitive to a few temperature increases around the ODT temperature. Above the critical temperature, G′ finally yields the terminal flow in the low frequency range. The morphological observation at various temperatures was determined using atomic force microscopy (AFM) equipped with environmental controller. This enabled in situ observation of structural change of SEBS induced by temperature and phase transition. We found that the layered texture, mostly aligned along the surface can be seen for SEBS‐A1 ranging from room temperature to 230 °C, though the image contrast reduced by an increase of temperature. SEBS‐A3 showed sphere domains at room temperature and also remains the structure at a critical temperature. The phase separated structure disappeared almost completely above ODT temperature, which was confirmed by the rheologial criteria. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 955–965, 2009 相似文献
1000.
ABSTRACTCurrent anvil designs and problems associated with various efforts to generate static high pressures beyond the limit of conventional diamond anvil cells (DACs) (~400?GPa) are reviewed. Pressures of up to 1?TPa have been reported by one research group using the double-stage DAC (ds-DAC) technique, but no other research group has successfully reproduced this high pressure result. Some research groups have used toroidal anvils, achieving pressures of >400?GPa. We have conducted numerous ds-DAC experiments and investigated the problems associated with such experiments. They include problems associated with various pressure scales in the multi-megabar region, difficulties in obtaining reliable X-ray diffraction patterns from micron-sized samples, and physical property measurements of tiny materials that may be harder than diamond. Each of these problems is discussed, following the summary of various experiments. 相似文献