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761.
DNA liquid-crystalline gel as adsorbent of carcinogenic agent 总被引:1,自引:0,他引:1
Dobashi T Furusawa K Kita E Minamisawa Y Yamamoto T 《Langmuir : the ACS journal of surfaces and colloids》2007,23(3):1303-1306
DNA liquid crystalline gel (LCG) has been newly prepared by a dialysis of concentrated DNA solutions into concentrated metal cation solutions. The condition for forming DNA LCG is examined by means of the insolubilization reaction. The shrinking ratio and the ratio of the thickness of LCG layer, delta, and the diameter of the dialysis tube, d0, do not depend on d0. The adsorption of one of carcinogenic agents, acridine orange is demonstrated. From the experimental results, the mechanism for forming DNALCG is discussed. 相似文献
762.
Narumi T Tomita K Inokuchi E Kobayashi K Oishi S Ohno H Fujii N 《Organic letters》2007,9(17):3465-3468
Chemo- and stereoselective synthesis of fluoroalkenes was achieved in excellent yields via Pd-catalyzed C-F bond activation. In this transformation, Et3N plays a crucial role to produce reactive hydride species such as Ph(EtO)SiH2 and Ph(EtO)2SiH by promoting dehydrogenative coupling. The reaction proceeds efficiently at 50 degrees C with a variety of substrates and is also useful for the synthesis of fluoroalkene peptidomimetics. 相似文献
763.
Kojima T Nakayama K Ikemura K Ogura T Fukuzumi S 《Journal of the American Chemical Society》2011,133(30):11692-11700
A coordinatively saturated ruthenium(II) complex having tetradentate tris(2-pyridylmethyl)amine (TPA) and bidentate 2,2'-bipyridine (bpy), [Ru(TPA)(bpy)](2+) (1), was oxidized by a Ce(IV) ion in H(2)O to afford a Ru(IV)-oxo complex, [Ru(O)(H(+)TPA)(bpy)](3+) (2). The crystal structure of the Ru(IV)-oxo complex 2 was determined by X-ray crystallography. In 2, the TPA ligand partially dissociates to be in a facial tridentate fashion and the uncoordinated pyridine moiety is protonated. The spin state of 2, which showed paramagnetically shifted NMR signals in the range of 60 to -20 ppm, was determined to be an intermediate spin (S = 1) by the Evans' method with (1)H NMR spectroscopy in acetone-d(6). The reaction of 2 with various oraganic substrates in acetonitrile at room temperature afforded oxidized and oxygenated products and a solvent-bound complex, [Ru(H(+)TPA)(bpy)(CH(3)CN)], which is intact in the presence of alcohols. The oxygenation reaction of saturated C-H bonds with 2 proceeds by two-step processes: the hydrogen abstraction with 2, followed by the dissociation of the alcohol products from the oxygen-rebound complexes, Ru(III)-alkoxo complexes, which were successfully detected by ESI-MS spectrometry. The kinetic isotope effects in the first step for the reaction of dihydroanthrathene (DHA) and cumene with 2 were determined to be 49 and 12, respectively. The second-order rate constants of C-H oxygenation in the first step exhibited a linear correlation with bond dissociation energies of the C-H bond cleavage. 相似文献
764.
Sawada D Tsukuda Y Saito H Kakuda S Takimoto-Kamimura M Ochiai E Takenouchi K Kittaka A 《Journal of the American Chemical Society》2011,133(18):7215-7221
In the study of the synthesis of 14-epi-19-norprevitamin D(3), we found 14-epi-19-nortachysterol derivatives through C6,7-cis/trans isomerization. We also succeeded in their chemical synthesis and revealed their marked stability and potent VDR binding affinity. To the best of our knowledge, this is the first isolation of stable tachysterol analogues. Surprisingly, 14-epi-19-nortachysterol derivatives exhibited an unprecedented binding configurations for the ligand binding pocket in hVDR, C5,6-s-trans and C7,8-s-trans triene configurations, which were opposite the natural C7,8-ene-configuration of 1α,25(OH)(2)D(3). 相似文献
765.
Planetary rovers are different from conventional terrestrial vehicles in many respects, making it necessary to investigate the terramechanics with a particular focus on them, which is a hot research topic at the budding stage. Predicting the wheel-soil interaction performance from the knowledge of terramechanics is of great importance to the mechanical design/evaluation/optimization, dynamics simulation, soil parameter identification, and control of planetary rovers. In this study, experiments were performed using a single-wheel testbed for wheels with different radii (135 and 157.35 mm), widths (110 and 165 mm), lug heights (0, 5, 10, and 15 mm), numbers of lugs (30, 24, 15, and 8), and lug inclination angles (0°, 5°, 10°, and 20°) under different slip ratios (0, 0.1, 0.2, 0.3, 0.4, 0.6, etc.). The influences of the vertical load (30 N, 80 N, and 150 N), moving velocity (10, 25, 40, and 55 mm/s), and repetitive passing (four times) were also studied. Experimental results shown with figures and tables and are analyzed to evaluate the wheels’ driving performance in deformable soil and to draw conclusions. The driving performance of wheels is analyzed using absolute performance indices such as drawbar pull, driving torque, and wheel sinkage and also using relative indices such as the drawbar pull coefficient, tractive efficiency, and entrance angle. The experimental results and conclusions are useful for optimal wheel design and improvement/verification of wheel-soil interaction mechanics model. The analysis methods used in this paper, such as those considering the relationships among the relative indices, can be referred to for analyzing the performance of wheels of other vehicles. 相似文献
766.
Hayami S Kato K Komatsu Y Fuyuhiro A Ohba M 《Dalton transactions (Cambridge, England : 2003)》2011,40(10):2167-2169
The cobalt(II) compounds with long alkyl chains, [Co(C12-terpy)(2)](BF(4))(2)·EtOH·0.5H(2)O(1·EtOH·0.5H(2)O) and [Co(C12-terpy)(2)](BF(4))(2) (1) was synthesized and characterized. The compound 1·EtOH·0.5H(2)O exhibits a "re-entrant spin crossover". The compound 1 exhibits the reentrant spin crossover and multi phase transitions with a wide thermal hysteresis loop. 相似文献
767.
Asymmetric autocatalysis initiated by chiral crystals containing racemic DL-serine was achieved. P- and M-crystals of DL-serine acted as the source of chirality of asymmetric autocatalysis to afford highly enantioenriched (>99.5% ee) (S)- and (R)-pyrimidylalkanols after the amplification of ee. This is the first example of the usage of the crystal, which contains the same number of D- and L-enantiomers as an origin of chirality in enantioselective synthesis. 相似文献
768.
We study an electric quadrupole contribution to sum frequency generation (SFG) at air∕liquid interfaces in an electronically and vibrationally nonresonant condition. Heterodyne-detected electronic sum frequency generation spectroscopy of air∕liquid interfaces reveals that nonresonant χ((2)) (second-order nonlinear susceptibility) has a negative sign and nearly the same value for all eight liquids studied. This result is rationalized on the basis of the theoretical expressions of χ((2)) with an electric quadrupole contribution taken into account. It is concluded that the nonresonant background of SFG is predominantly due to interfacial nonlinear polarization having a quadrupole contribution. Although this nonlinear polarization is localized at the interface, it depends on quadrupolar χ((2)) in the bulk as well as that at the interface. It means that the sign of nonresonant χ((2)) bears no relation to the "up" versus "down" alignment of interfacial molecules, because nonresonant χ((2)) has a quadrupolar origin. 相似文献
769.
Kubo K Shiga T Yamamoto T Tajima A Moriwaki T Ikemoto Y Yamashita M Sessini E Mercuri ML Deplano P Nakazawa Y Kato R 《Inorganic chemistry》2011,50(19):9337-9344
The electrochemical oxidation of an acetone solution containing [Mn(III) (5-MeOsaltmen)(H(2)O)](2)(PF(6))(2) (5-MeOsaltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene)bis(5-methoxysalicylideneiminate)) and (NBu(4))[Ni(dmit)(2)] (dmit(2-) = 2-thioxo-1,3-dithiole-4,5-dithiolate) afforded a hybrid material, [Mn(5-MeOsaltmen)(acetone)](2)[Ni(dmit)(2)](6) (1), in which [Mn(2)](2+) single-molecule magnets (SMMs) with an S(T) = 4 ground state and [Ni(dmit)(2)](n-) molecules in a charge-ordered state (n = 0 or 1) are assembled in a layer-by-layer structure. Compound 1 crystallizes in the triclinic space group P1 with an inversion center at the midpoint of the Mn···Mn dimer. The [Mn(2)](2+) unit has a typical nonplanar Mn(III) dimeric core and is structurally consistent with previously reported [Mn(2)] SMMs. The six [Ni(dmit)(2)](n-) (n = 0 or 1) units have a square-planar coordination geometry, and the charge ordering among them was assigned on the basis of ν(C═C) in IR reflectance spectra (1386, 1356, 1327, and 1296 cm(-1)). The [Mn(2)](2+) SMM and [Ni(dmit)(2)](n-) units aggregate independently to form hybrid frames. Electronic conductivity measurements revealed that 1 behaved as a semiconductor (ρ(rt) = 2.1 × 10(-1) Ω·cm(-1), E(a) = 97 meV) at ambient pressure and as an insulator at 1.7 GPa (ρ(1.7GPa) = 4.5 Ω·cm(-1), E(a) = 76 meV). Magnetic measurements indicated that the [Mn(2)](2+) units in 1 behaved as S(T) = 4 SMMs at low temperatures. 相似文献
770.
Takao Fujimori Kousuke KurisakiTadashi Okobira Kazuya UezuKazuhisa Yoshimura 《Polymer Degradation and Stability》2011,96(8):1516-1521
This paper deals with the desulfonation properties of some strong acid cation-exchange resins. The sulfate concentration in solution is continuously increased when a strong acid cation-exchange resin is mixed with water. The leaching of sulfate results from the desulfonation of the fixed group, and the amount of leached sulfate depends on the counter ion charge, the crosslinking degree and the exchanger matrix. The effects of the counter ion charge on the desulfonation rate suggested that the counter ion induces the nucleophilic attack of a water molecule on the sulfo group. This interpretation was supported by semiempirical molecular orbital calculations for the C6H5SO3−Mm+ (Mm+ = Na+, Mg2+ and Al3+) systems, and the transition state of the Na+ system was successfully predicted by DFT calculations. The crosslinking degree influenced the desulfonation rate, which can be related to the decreasing hydration number of each counter ion in the resin phase with the increasing crosslinking degree. Furthermore, different exchanger matrices produced the differences in the rates, which may be derived from the electron-density donation from the exchanger matrix to the sulfo group. The desulfonation is governed by the electron-density of the sulfur atom and the water activity in the solid phase. 相似文献