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991.
Grand canonical Monte Carlo and configurational bias Monte Carlo techniques were employed to simulate the adsorption of binary mixtures of butane isomers and quaternary mixtures in nine zeolites at 300 K. For binary mixtures the results show there is a critical pore size, which is 10-membered-ring about 5.6 Å. The channel sizes of BEA, ISV, MOR and CFI are larger than this critical pore size, they prefer i-butane than n-butane, whereas TON with smaller channel size than critical pore size prefers n-butane than i-butane, but its selectivity decreases with pressure increasing. MFI, MEL and TER prefer i-butane than n-butane at low pressure, but with pressure increasing, the selectivity is reversed. BOG prefers i-butane than n-butane but the selectivity decreased with pressure increasing. It demonstrates that the adsorption and selectivity are controlled by both pore size and pore structure. The n-butane–i-butane–n-pentane–2-methylbutane quaternary mixtures adsorbed in these nine zeolites were studied, and the results show alkane chain length dependence at low pressure, but the adsorption is controlled by pore size and structure with pressure increasing in all the zeolites except for TON and BOG. 相似文献
992.
ZHAO Chunxia XU Guowang SHI Xianzhe MA Jianmei ZHANG Yan L?Shen & YANG Qing . Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian China . Cell Laboratory Second Affiliated Hospital Dalian Medical University Dalian China 《中国科学B辑(英文版)》2004,47(2):166-172
With the accomplishment of Human Genome Project (HGP), single nucleotide polymorphism (SNP) and mutation detection in human genome are becom-ing a new researching focus. These researches can help us to understand the phenotype diversity of indi-vidual, disease susceptibility and drug resistance of different colonies. Traditional method used for muta-tion detection is slab gel electrophoresis, which re-mains labor-intensive and time-consuming because of the requirement of radioactivity or te… 相似文献
993.
Anthraquinoid tautomers participate in the ionization of purpurin. The tautomerism takes place in both ground and excited states of the molecules; the excited state is more sensitive to the tautomerism. The solvation and ionization shift the tautomeric equilibria. In the experimental absorption spectra of purpurin, the major bands correspond to the 9,10-, 1,4-, and 1,10-anthraquinoid tautomers; anions with the 9,10-anthraquinoid structure are not detected. The position and intensity of the π,π* bands, and also the quantum-chemical parameters linearly correlate with the degree of ionization of purpurin. 相似文献
994.
995.
V. I. Grishkovets A. E. Kondratenko N. V. Tolkacheva A. S. Shashkov V. Ya. Chirva 《Chemistry of Natural Compounds》1994,30(6):689-692
The leaves of common ivy have yielded 11 triterpene glycosides: the 3-O-α-L-pyranosides of oleanolic acid (1), of echinocystic
acid (2), and of hederagenin; the 3-O-[O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside]s of oleanolic acid (4), of echinocystic
acid (5), and of hederagenin (6); the O-α-L-rhamnopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester of
hederagenin 3-O-α-L-pyranoside (7); the O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl ester of hederagenin 3-O-[O-α-L-pyranosyl-(1→2)-α-L-arabinopyranoside]
(9); and the O-α-L-rhamnopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→6)-O-β-D-glucopyranosyl esters of oleanolic acid, echinocystic
acid, and hederagenin 3-O-[O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside]s (8), (10), and (11), respectively. This is the
first time that compounds (1), (2), (5), (7), (9), and (10) have been found in this plant.
Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 742–746, November–December, 1994. 相似文献
996.
I.A. Zakharova Ya.V. Salyn I.A. Garbouzova V.T. Aleksanyan M.A. Prianichnicova 《Journal of organometallic chemistry》1975,102(2):227-238
The infrared and Raman spectra of norbornadiene complexes of Pd, Pt, Rh and Fe have been studied. An assignment of the normal modes is given and the ligand vibrations in the complex are compared with those for “free” norbornadiene. The ν(CC) stretching frequency of coordinated norbornadiene is from 1575 cm?1 to over 1400 cm?1.The strength of the metal—ligand bond increases in the series Pd < Pt < Rh and for halogen complexes in the series chloride < bromide < iodide. ESCA spectroscopy data obtained are in agreement with these conclusions. 相似文献
997.
DNA works as hereditary material and plays vital role in life science. The study of the binding of small molecules complex to DNA has been the focus of intense investigation, owning to their stereo and sequence specific interaction with the double helix1-… 相似文献
998.
A. D. Grishina L. Licea-Jimenez L. Ya. Pereshivko T. V. Krivenko V. V. Savel’ev R. W. Rychwalski A. V. Vannikov 《High Energy Chemistry》2006,40(5):341-347
Photorefractive materials based on unplasticized polymers that have a high glass-transition temperature and the frozen random orientation of chromophores were prepared by layer casting. Under these conditions, only the third-order susceptibility has a nonzero value, increasing with an increase in the conjugation-chain length and reaching considerable values in the case of nanosized molecules, such as single-wall carbon nanotubes (SWNTs). In SWNT-containing polyvinylcarbazole, the photoelectric sensitivity and photorefractive characteristics were measured at 1064 nm. Using electric-field induced second-harmonic generation, the third-order susceptibility was estimated. In a composite containing 0.26 wt % SWNT, the diffraction grating is displaced by 5° relative to the interference pattern, the result that is presumably due to the close mobility of unlike charge carriers. Therefore, the beam-coupling gain coefficient Γ and the net gain Γ-α have low values, which are 53 and 42 cm?1, respectively, at 115 V/μm. 相似文献
999.
E.M. Akulonok V.Ya. Khaimov-Malkov Yu.K. Danileiko A.A. Manenkov V.S. Nechitailo T.P. Lebedeva 《Journal of solid state chemistry》1978,26(1):17-25
A problem of trap diffusion, that is diffusion of point defects in crystals participating in a solid-phase chemical reaction with motionless impurity ions, is solved. Time dependences of the reaction-front displacement, Xf, and its steepness, are determined analytically for N0 ? C0 and numerically for all relations of N0 and C0where C0 and N0 are the initial concentration of impurity and the eqilibrium defect concentration, respectively, D is a diffusion coefficient, and g is a chemical reaction constant. Dependence of Xf vs C0 and t is confirmed for oxygen annealing of corundum crystals doped with titanium which, reacting with the point defects, changes its valency. The data are obtained for dependence of displacement Xf upon partial oxygen pressure and thermotreatment temperature as well as upon the sign of the constant electric field applied to the sample. From these data we conclude that the reaction of titanium impurity, changing from the three-valent to the tetravalent state at the activation energy of 80 ± 8.5 kcal/mole is due to anisotropic diffusion of charged aluminum vacancy and holes in the valence band. The diffusion coefficient for that process at 1500°C is estimated to be larger than 10?5 cm2/sec. Using the trap-diffusion features, the concentration of optical centers of the 0.315-μm absorption band in ruby is also estimated. 相似文献
1000.
Filinchuk Ya. E. Pavlyuk A. V. Ciunik L. Z. Mys'kiv M. G. 《Russian Journal of Coordination Chemistry》2004,30(11):818-824
The crystals of N-allylisoquinolinium chlorides of the compositions [C9H7N(C3H5)]2CuIICl4 (I), [C9H7N(C3H5)]CuICl2 · H2O (II), and [C9H7N(C3H5)]CuICl1.43Br0.57 · H2O (III) were prepared by alternating-current electrosynthesis. X-ray diffraction analysis (using diffractometer models DARCH1 for I, STOE for II, and KUMA/CCD for III, MoK
radiation) showed that the crystals of I are monoclinic, space group P21/n, a = 14.91(1) Å, b = 10.41(1) Å, c = 16.90(1) Å, = 109.73(8)°, V = 2470(8) Å3, Z = 4. The crystals of isostructural compounds II and III are triclinic, space group P, Z = 2; crystals II: a = 7.2446(6) Å, b = 7.4379(6) Å, c = 12.110(1) Å, = 80.95(1)°, = 85.55(1)°, = 86.60(1)°, V = 641.8(2) Å3; crystals III: a = 7.253(2) Å, b = 7.459(4) Å, c = 12.151(5) Å, = 80.82(4)°, = 83.73(3)°, = 86.81(4)°, V = 644.6(9) Å3. The structure of I is composed of CuIICl4
2– tetrahedra and N-allylisoquinolinium cations united by C–H···Cl hydrogen bonds in corrugated layers. The crystal structures of -complexesII and III are built of [C9H7(C3H5)]2Cu2
IX4 dimers, which form layers along the c axis due to the C–H···X hydrogen bonds. An important role in the structure formation is played by water molecules, which crosslink the organometallic layers to form a three-dimensional framework through the O–H···X contacts. 相似文献