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981.
Yuki Miyazawa Makoto Sugimoto Ayumi Tanaka-Oda Hidefumi Makabe 《Tetrahedron letters》2019,60(36):151039
Syntheses of (+)-goniopypyrone and (+)-goniotriol isolated from Goniothalamus giganteus were achieved. The key steps involve Pd-catalyzed carbonylation for lactone ring formation and diastereoselective reduction of ynone using the (R)-CBS catalyst and borane dimethyl sulfide complex. 相似文献
982.
Mizuki Yamada Mio Matsumura Erina Sakaki Shih-yun Yen Masatoshi Kawahata Tadashi Hyodo Kentaro Yamaguchi Yuki Murata Shuji Yasuike 《Tetrahedron》2019,75(10):1406-1414
A simple method for the synthesis of monoselenides and diselenides having 1,2,3-triazole ring is described herein. The three component reaction of ethynylstibanes, organic azides, and selenium powder is catalyzed by CuI (10?mol%) using 1,10-phenanthroline as the ligand (10?mol%) under aerobic conditions. Either selenides or diselenides can be synthesized by selecting the appropriate amount of selenium powder for otherwise identical reaction conditions. The obtained selenides and diselenides having a 1,2,3-triazole ring are all novel compounds. By using an antimony reagent, this one-pot reaction provides regioselective double Se-arylation under simple reaction conditions. 相似文献
983.
Mao Oide Yuki Sekiguchi Asahi Fukuda Koji Okajima Tomotaka Oroguchi Masayoshi Nakasako 《Journal of synchrotron radiation》2018,25(5):1379-1388
In structure analyses of proteins in solution by using small‐angle X‐ray scattering (SAXS), the molecular models are restored by using ab initio molecular modeling algorithms. There can be variation among restored models owing to the loss of phase information in the scattering profiles, averaging with regard to the orientation of proteins against the direction of the incident X‐ray beam, and also conformational fluctuations. In many cases, a representative molecular model is obtained by averaging models restored in a number of ab initio calculations, which possibly provide nonrealistic models inconsistent with the biological and structural information about the target protein. Here, a protocol for classifying predicted models by multivariate analysis to select probable and realistic models is proposed. In the protocol, each structure model is represented as a point in a hyper‐dimensional space describing the shape of the model. Principal component analysis followed by the clustering method is applied to visualize the distribution of the points in the hyper‐dimensional space. Then, the classification provides an opportunity to exclude nonrealistic models. The feasibility of the protocol was examined through the application to the SAXS profiles of four proteins. 相似文献
984.
Yuki Izumi 《Stochastics An International Journal of Probability and Stochastic Processes》2018,90(1):102-150
In this paper, we consider the differentiability in the sense of the Malliavin calculus of solutions to backward stochastic differential equations (BSDEs for short). It is known that a solution is differentiable in the sense of the Malliavin calculus and the derivative is also a solution to a linear BSDE. Under additional conditions, we will show that the higher order differentiability of a solution to a BSDE and that it also becomes a solution to a linear BSDE. 相似文献
985.
Uji S Terashima T Nishimura M Takahide Y Konoike T Enomoto K Cui H Kobayashi H Kobayashi A Tanaka H Tokumoto M Choi ES Tokumoto T Graf D Brooks JS 《Physical review letters》2006,97(15):157001
Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space. 相似文献
986.
Eriko Watanabe Sai‐Cheong Chung Shin‐ichi Nishimura Yuki Yamada Masashi Okubo Keitaro Sodeyama Yoshitaka Tateyama Atsuo Yamada 《Chemical record (New York, N.Y.)》2019,19(4):792-798
Owing to developments in theoretical chemistry and computer power, the combination of calculations and experiments is now standard practice in understanding and developing new materials for battery systems. Here, we briefly review our recent combined studies based on density functional theory and molecular dynamics calculations for electrode and electrolyte materials for sodium‐ion batteries. These findings represent case studies of successful combinations of experimental and theoretical methods. 相似文献
987.
The effective charge of hydrophobic surfaces and in particular of the air–water interface is a crucial parameter for electrochemistry, colloidal chemistry and interfacial science, but different experiments give conflicting estimates. Zeta-potential and disjoining-pressure measurements point to a strongly negative surface charge, often interpreted as being due to adsorbing hydroxide ions. In contrast, surface tension measurements of acids and bases suggest the hydronium ion to be surface active, in agreement with some surface-specific non-linear spectroscopy results. The air–electrolyte interfacial tension exhibits a characteristic minimum at millimolar electrolyte concentration for all salts, the so-called Jones–Ray effect, which points to competitive adsorption mechanisms present in dilute electrolyte solutions. We show that all these puzzling experimental findings can be explained by the presence of trace amounts of surface-active charged impurities, most likely anionic surfactants. 相似文献
988.
Heimei Yuki Yoshio Okamoto Yoshiteru Kuwae Koichi Hatada 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1933-1946
o-Methoxystyrene was polymerized with n-butyllithium (n-BuLi), Na naphthalene, and K dispersion as initiators in tetrahydrofuran (THF) and toluene. The stereoregularity of the polymer was investigated by means of the NMR spectroscopy. The methoxy resonance of the spectrum split into ten components due to the tactic pentads. It was found by x-ray examination that the polymer obtained by n-BuLi in toluene at ?45°C was crystalline and highly isotactic. In THF, the stereospecificity of the polymerization was independent of the initiator, and the isotacticity of the polymer increased with increasing reaction temperature. In toluene, the stereospecificity depended on the initiator; i.e., n-BuLi gave a polymer with higher isotacticity than that given by phenylsodium. The fraction of isotactic triad of the polymer obtained by n-BuLi in toluene at ?78°C was more than 90%, but 50% at 50°C. The presence of ca. 1% THF in toluene led to a steep decrease in the isotacticity even at ?78°C. The tacticity of the polymer given by Na naphthalene was not affected by the existence of NaB(C6H5)4 in THF. The polymerization in THF could be explained by Bovey's “single σ” process, while a penultimate effect was observed in the polymerization by n-BuLi in toluene. 相似文献
989.
Tanaka H Tokumoto M Ishibashi S Graf D Choi ES Brooks JS Yasuzuka S Okano Y Kobayashi H Kobayashi A 《Journal of the American Chemical Society》2004,126(34):10518-10519
Rigorous evidence of metallicity of a molecular crystal consisting of single-component neutral molecules is disclosed by observing the Fermi surface through magnetic quantum oscillations. Torque magnetometry measurements of de Haas-van Alphen oscillatory signals in a single crystal of [Ni(tmdt)2] molecules (tmdt = trimethylenetetrathiafulvalenedithiolate) were performed by using a sensitive microcantilever at low temperatures in high magnetic fields to 45 T. The observed signals for all directions of magnetic field revealed unambiguously the presence of three-dimensional Fermi surfaces for both holes and electrons. The results are consistent with electronic band structure calculations for [Ni(tmdt)2]. 相似文献
990.
The decay rate of 7Be electron capture was measured in C60 and Be metal with a reference method. The half-life of 7Be endohedral C60 ((7)Be@C(60)) and 7Be in Be metal (Be metal (7Be)) is found to be 52.68+/-0.05 and 53.12+/-0.05 days, respectively. This amounts to a 0.83% difference in electron-capture decay half-life between (7)Be@C(60) and Be metal (7Be). Our result is a reflection of the different electron wave functions for (7)Be@C(60) inside C60 compared to the situation when 7Be is in a Be metal. 相似文献