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71.
S-Methyldithizone(5-methylmercapto-1,5-diphenylformazan) reacts with the chlorides of copper(II), mercury(II) and phenylmercury(II) to give the 1:1 chelates [CuCl(MeDz), HgCl(MeDz) and C6H5Hg(MeDz)] and with nickel(II) and palladium(II) to give the 1:2 chelates, M(MeDz)2. All these complexes are intensely coloured in chloroform solution. No complexes are formed from cobalt(II), manganese(II) or zinc(II) or from the nitrates or acetates of copper and mercury. Coordination increases the reactivity of the sulphur atom in dithizone. Whereas dithizone is unaffected by methyl iodide, nickel dithizonate, Ni(HDz)2, gives Ni-(MeDz)2 when heated with methyl iodide in ethanol in the presence of sodium acetate; palladium dithizonate behaves similarly. The 1:1 adduct of nickel dithizonate with 2,2'-bipyridyl gave only Ni(MeDz)2 on treatment with methyl iodide, and this complex would not form an adduct with bipyridyl. On standing in the light, Ni(MeDz)2 reacted photochemically to give the yellow isomer of S-methyl-dithizone. 相似文献
72.
The isocratic reversed-phase liquid chromatography of the angiotensins and a number of their synthetic analogues is described. Complete separation of 10 out of 12 peptides was achieved through a solvent optimization strategy with a total analysis time of about 20 min. The retention behavior of the angiotensins studied was described in terms of the hydrophobic contribution of their amino acid residues; there was good correlation between predicted and experimental retention for those peptides that were retained by a common mechanism. However, because ion-pair chromatography was required for good peak symmetry, retention was substantially modulated by the presence of acidic and basic residues. The limit of detection of these peptides was 3-5 pmol by UV absorbance at 214 nm. For those peptides containing a primary amino group the detection limit was improved by two orders of magnitude by fluorogenic derivatization with naphthalene-2,3-dicarboxaldehyde/cyanide to the corresponding N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives. The contribution of the CBI ring system to retention was also investigated. 相似文献
73.
The viscosity deviation (Δη), the excess molar volume (V
E) and the ultrasonic speed (u) have been investigated from viscosity (η) and density (ρ ) measurements of binary liquid mixtures of 1,2-dimethyoxyethane with methanol, ethanol, propan-1-ol, butan-1-ol,
pentan-1-ol, hexan-1-ol or octan-1-ol over the entire range of composition at 298.15 K. The excess volumes are negative over
the entire range of composition for all of the mixtures with the exception of hexan-1-ol and octan-1-ol. The excess isentropic
compressibilities (K
S
E) and viscosity deviations are negative for all of the mixtures. The magnitudes of the negative values of V
E decrease with the number of carbon atoms of the alkan-1-ol. The trend of increasing K
S
E values with the chain length of the alkanol is similar to that observed in the case of V
E. Graphs of V
E, Δ η, K
S
E, Δ u, L
f
E and Z
E against composition are presented as a basis for a qualitative discussion of the results. 相似文献
74.
A structurally related series of fluorinated nonionic oxyethylene glycol surfactants of the type C(m)F(2m+1)(CH(2))(n)O[(CH(2)CH(2)O)(p)H], denoted C(m.n)E(p) (where m=4, 6, or 7, m=1 or 2, and p=4 or 6) were synthesized and their surface behavior in aqueous solution was characterized. The ability of these surfactants to form water-in-hydrofluorocarbon (HFC) propellant 134a microemulsions suitable for use in the aerosolized delivery of water-soluble drugs has been investigated. Phase studies showed that, regardless of the composition used, clear one-phase systems could not be prepared if a fluorinated nonionic surfactant was used alone, or in combination with a short or medium fluorocarbon alcohol cosurfactant. Clear one-phase systems could, however, be prepared if a short-chain hydrocarbon alcohol, such as ethanol, n-propanol, or n-pentanol, was used as cosurfactant, with the extent of the one-phase region increasing with decreased chain length of the alcohol cosurfactant. Light-scattering studies on a number of the hydrocarbon-alcoholcontaining systems in the propellant-rich part of the phase diagram showed that only systems prepared with C(4.2)E(6) and propanol contained microemulsion droplets (all other systems investigated were considered to be cosolvent systems). 相似文献
75.
A new, simple, selective and sensitive method for the spectrophotometric determination of antimony in rain water is described. It includes preconcentrating Sb with surfactants (i.e. cetylpyridinium chloride (CPC) and Triton X-100 (TX-100)) into toluene and allowing the extract to react with a dye, i.e. brilliant green (BG). The value of apparent molar absorptivity is 5.55 × 105 L-mol–1· cm–1 at λmax = 620 nm; the detection limit is 3 ng/mL Sb in rain water at 3-fold preconcentration. 相似文献
76.
Frank G. Riddell Eric S. Turner Alan R. Katritzky Ranjan C. Patel Fernando M.S. Brito-Palma 《Tetrahedron》1979,35(11):1391-1398
The synthesis and variable temperature 1H and 13C NMR spectra of three tetrahydro-1,2,4-oxadiazines are reported. The N(4)-Me inversion barriers are 6.8–7.0 (ax→ts) and 7.4–7.9 kcal mol?1 (eq→ts) with ΔG° 0.6–0.9 kcal mol?1. The N(2)-Me inversion barriers are 10.4–11.4 (ax→ts) and 11.6–13.1 kcal mol?1 (eq→ts) with ΔGδ 1.2–1.7 kcal mol?1. The barrier to ring inversion is ca. 12.7 kcal mol?1. “R value” analysis shows the ring to have a 56.5±2δ dihedral angle about the C(5)-(6) bond, indicative of the expected chair conformation. 相似文献
77.
A simple, rapid and precise reverse-phase high performance liquid chromatographic method has been developed for the quantitative determination of eugenol from the extract of dried powder of Cinnamomum tamala leaves and its polyherbal formulation. Chromatographic analysis was carried out on Zorbax C18 column (150 mm × 4.6 mm, 5 μm) with a mobile phase of mixture of water, acetonitrile and methanol in the volume ratio of 50:40:10, at a flow rate of 1.0 mL min-1. Quantitation was performed using a UV-visible detector at 210 nm. Good linearity was obtained over the ranges of 0.20–3.0 μg mL-1 for eugenol. 相似文献
78.
Vaghela SS Jethva AD Gohil MS Subbarayappa A Gour PM Susarla VS Gadde R Ghosh PK 《Annali di chimica》2003,93(9-10):841-848
A textile dye effluent containing chiefly reactive azo dyes has been treated electrochemically for discoloration and COD (chemical oxygen demand) reduction at different current densities, flow rates and dilution. Experiments have been carried out in a thin electrochemical reactor under single pass conditions using a dimensionally stable catalytic anode (DSA) and a stainless steel cathode. 相似文献
79.
The factors influencing the formation of water-in-134a-propellant microemulsions using the fluorinated ionic surfactants ammonium perfluorooctanoate, ammonium perfluoroheptanoate, and sodium perfluorooctanoate has been determined. None of the fluorinated ionic surfactants could be used to prepare clear, one-phase systems when used as sole surfactant, but they could be when combined with a short-chain fluoro- or hydrocarbon alcohol in surfactant:cosurfactant weight-mixing ratios (K(m)) in the range 1:2 to 2:1. When hydrocarbon alcohols were used this clear region extended over a wide range of compositions and was confirmed by means of photon correlation spectroscopy (PCS) to contain microemulsion droplets in the propellant-rich part of the phase diagram. PCS studies performed in the presence of the water-soluble drug terbutaline sulfate showed that it was possible to solubilize the drug within water-in-propellant microemulsion droplets. These studies confirm for the first time that it is possible to prepare water-in-propellant 134a microemulsions using fluorinated ionic surfactants and to solubilize water-soluble drugs within these systems. 相似文献
80.
Urmila H. Patel Chaitanya G. Dave Mukesh M. Jotani Hetal C. Shah 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o697-o699
The title compound, C20H16N2O, has two molecules in the asymmetric unit and the crystal structure shows that the central pyridine ring of each molecule has a flat boat conformation. The terminal C atom in one of the molecules is disordered over two positions, with relative occupancies of 0.594 (14) and 0.398 (14). Intermolecular C—H?N and C—H?π interactions and π–π stacking, along with intramolecular C—H?N and C—H?π interactions, help to stabilize the structure. 相似文献