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191.
Conclusions The kinetics of the reaction of triethylphosphite with-acetoxyethylmethyl ketone was studied by infrared spectroscopy, and was found to be of the second order.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2616, November, 1968. 相似文献
192.
A flow injection micro-analyser with an integrated injection device and photometric detection is described. Channels measuring 205-295 μm depth by 265-290 μm maximum width were manufactured by deep UV lithography on two layers of urethane-acrylate oligomers-based photoresist. Hypodermic syringe needles (450 μm diameter) were connected to the channels for introduction of solutions into the system. Plastic optical fibres were connected to the ends of a 5.0 mm long channel, in order to conduct the light from and to a homemade photometer. The device has a total volume of 7.0 μL and three different sample volumes (0.09, 0.22 and 0.30 μL) can be inserted into the system by choosing the appropriate loop of the hydrodynamic injection approach. The micro-analyser, designed as a single line manifold, was evaluated by determining chloride in waters (mercuric thiocyanate method), and chromium (VI) in wastewater and total chromium in metallic alloys (diphenylcarbazide method). For chloride determination two micro-pumps were employed to impel the solutions, while for chromium determination this task was performed by a conventional peristaltic pump. The results obtained in all determinations did not differ significantly from the reference methods at a confidence level of 95%. In the chloride determination, a flow rate of 50 μL min−1 was used, providing a sample frequency of 45 injection h−1, generating ca. 0.7 mg of Hg(II) after an 8-h working day (ca. 20 mL of solution). This result suggests the potential of the micro-analyser towards the reduction of waste, following the philosophy of Green Chemistry. 相似文献
193.
The algorithm proposed previously for calculating the full configuration interaction using the variation matrix of the wave
operator involves the numerical solution of the corresponding incomplete eigenvalue problem based on iterated Krylov’s subspaces.
In practice, that means using the multistep gradient method as a special version of the Lanczos method. The high efficiency
of this algorithm, which can readily be used in personal computer calculations, is proved by particular ab initio calculations
of the full configuration interaction for the helium and beryllium atoms as well as by semiempirical calculations of π-shells
for naphthalene and diphenylene. The algorithm is of particular assistance in obtaining numerous excited states, which are
used for determining various spectral sums (polarizability, van der Waals interaction constants, and photoionization cross
sections).
Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 1, pp. 14–22, January–February, 1997. 相似文献
194.
Optimal conditions for the complexation of transition metal ions [Cu(II), Ni(II), Co(II, III), and Fe(II, III)] with 1-nitroso-2-naphthol-2,6-disulfonic
acid have been determined by spectrophotometry in the presence of cationic (cetylpyridinium and cetyltrimethylammonium bromides)
and nonionic (OP-10, neonol) surfactants. The introduction of nonionic surfactants does not influence the optical parameters
of the system, while the introduction of cationic ones leads to hyperchromic and hypsochromic (for the system Fe(III)-NRS-surfactant)
effects. The stoichiometric ratios determined by the method of isomolar series and treatment of the saturation curves of cationic
surfactants at pH 4.0 are Me(II): R: surfactant = 1: 2: 4, Me(III): R: surfactant = 1: 3: 6. The molar absorption coefficients
and chromaticity parameters of ternary complexes have been determined. A 2–5-fold increase in the molar absorption coefficients
and chromaticity functions as compared to binary systems has been revealed. 相似文献
195.
Lubomír Lap?ík Barbora Lap?íková Ivo Krásny Ivana Kupská Richard W. Greenwood Kristian E. Waters 《Plasma Chemistry and Plasma Processing》2012,32(4):845-858
It was found in this study that the air plasma treatment of particular kaolinite has led to the change of its wettability, which was reflected in the decreased values of water contact angles of wetting from 88.7° for virgin kaolinite to 86.3° for 30?min air plasma treated one. Plasma treated samples show higher average surface energies in the wide range of coverage regimes in comparison to the virgin samples as determined by inverse gas chromatography. Results of these measurements confirmed our assumption, that air plasma treatment activates surface energy of the crystal planes of the kaolinite as reflected in the broadened dispersive surface energy distribution after 10?min treatment time. However with prolonged 30?min treatment time the dispersive surface energy distribution profile was decreased. We assume, that the latter decrease reflects the distorsion of the crystal lattice of the kaolinite as confirmed by FTIR analysis as reflected in changes of Si?CO?CSi and Al2O?CH characteristic absorption bands. Calculated dispersive surface free energy for 24?% surface coverage was increased from original 35?mJ/m2 to 40.3 and 40.8?mJ/m2 for 10 and 30?min treatment times. There were determined yield locus and flow function dependencies at different stress levels for virgin and different time plasma treated samples (flow index??ff c , effective angle of internal friction???? e , unconfined yield strength???? c ). It was found that by plasma treatment the character of the flow was shifting from region of very cohesive (ff c ?=?2.39) to the cohesive (ff c ?=?3.19). For untreated samples effective angle of internal friction was decreased with increasing applied consolidation stress, while for plasma treated kaolinite it was increased. 相似文献
196.
M.?V.?Markova L.?N.?Sobenina I.?A.?Ushakov A.?V.?Ivanov B.?A.?TrofimovEmail author 《Russian Journal of Organic Chemistry》2017,53(2):184-191
Aminomethylation of 2-methyl(aryl)-, 2-aryl-3-alkylpyrroles, 4,5,6,7-tetrahydroindole and its 1-vinyl- and 1-benzyl-substituted derivatives with a mixture of 5% water-ethanol solution of formaldehyde and cyclic amine (pyrrolidine, piperazine, and morpholine) without catalyst at room temperature leads to the formation of the corresponding 2-aminomethylpyrroles and 2-aminomethyl-4,5,6,7-tetrahydroindoles in up to 92% yields. In reaction of 1-vinyl-4,5,6,7-tetrahydroindole with formaldehyde water solution and piperazine in a 60% yield 1,4-bis(1-vinyl-4,5,6,7-tetrahydroindol-2-yl)piperazine was obtained, a promising bifunctional monomer and a building block for the synthesis of new indole derivatives, in particular, of biologically active polymers. In the reaction of 2-methylpyrrole and 4,5,6,7-tetrahydroindole with formaldehyde and morpholine along with the С2-aminomethylation the 1-hydroxymethylation of the pyrrole ring was observed. 相似文献
197.
S. M. Frolov V. I. Zvegintsev V. S. Ivanov V. S. Aksenov I. O. Shamshin D. A. Vnuchkov D. G. Nalivaichenko A. A. Berlin V. M. Fomin 《Doklady Physical Chemistry》2017,474(1):75-79
First experimental investigations were carried out into the detonation combustion of hydrogen in a demonstrator of an original-design air-breathing ramjet while blowing with an air flow at Mach 4 to 8 in an impulse wind tunnel, and for the first time under these conditions, continuous spin and longitudinal pulsed modes of detonation combustion of hydrogen in an annular combustor were detected. 相似文献
198.
L. S. Skogareva S. Yu. Kottsov T. O. Shekunova A. E. Baranchikov O. S. Ivanova A. D. Yapryntsev V. K. Ivanov 《Russian Journal of Inorganic Chemistry》2017,62(9):1141-1146
It has been shown for the first time that the use of hydrogen peroxide allows precipitation of rare earth orthophosphates (La–Tb) from phosphoric acid solutions at temperatures below 100°C. Either anhydrous or hydrated orthophosphates with monazite or rhabdophane structure, respectively, can be obtained depending on rare earth element position in lanthanide series and precipitation conditions (orthophosphoric acid and hydrogen peroxide concentration). Hydrated orthophosphates with rhabdophane structure can be prepared by precipitation with hydrogen peroxide for all studied rare earth elements. 相似文献
199.
Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)2], and their benzene solvates [M(Py)(Mdtc)2] · 0.5C6H6 were synthesized. The electron paramagnetic resonance method and solid-state 13C and 15N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)2], and in its solvate, [Cu(Py)(Mdtc)2] · 0.5C6H6 is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)2]. In the solvated adduct [Cu(Py)(Mdtc)2] · 0.5C6H6, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)2] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc–ligands in [Zn(Py)(Mdtc)2] · 0.5C6H6. Signals in the 15N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn2(Mdtc)4] species is accompanied by the dissociation of binuclear molecules. 相似文献
200.
Anthony J. Burke Helmut W. Schmalle Bernard A. Brady W. Ivo O'Sullivan 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):484-486
The title compound, C17H14O4, is an unprecedented new synthetic isoaurone‐type enol ether that has the E configuration. The planar furanone ring is fused to a methoxybenzene ring system, with an interplanar angle of 175.7 (1)°. Due to this ring fusion, the six‐membered ring has a significant amount of ring strain, as shown by the internal ring angle range of 115.8 (1)–124.7 (1)°, whereas the vinylic phenyl ring has internal angles between 119.7 (1) and 120.2 (1)°. The molecules form infinite hydrogen‐bonding layers along the b direction of the form C—H?O, where the keto O atom acts as a bifurcated acceptor. These layers are connected along the c direction by another hydrogen bond with a methoxy H atom as donor. In addition to this connection, the layers are stacked via centres of symmetry by a pair of symmetry‐related benzofuranone ring systems. 相似文献