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151.
M. S. R. Swamy T. P. Prasad B. R. Sant 《Journal of Thermal Analysis and Calorimetry》1979,16(2):471-478
The thermal decomposition of ferrous sulphate heptahydrate was carried out in air under dynamic and isothermal conditions. The intermediate phases were identified by chemical analysis and an X-ray technique. Ferrous sulphate heptahydrate is converted to tetrahydrate and monohydrate, but this conversion is accompanied by oxidation. Fe(OH)SO4 and Fe2O(SO4)2 are formed as oxidation products, and the latter decomposes to ferric oxide directly and/or through Fe2(SO4)3.
The authors express their grateful thanks to Prof. P. K. Jena, Director, for his keen interest and permission to publish the paper, and to Dr. A. Lakshminarayana for the X-ray measurements. One of us (MSRS) also thanks the Regional Research Laboratory (CSIR) for a fellowship. 相似文献
Zusammenfassung Die thermische Zersetzung von Eisen(II)sulfat Heptahydrat wurde in Luft unter dynamischen und isothermen Bedingungen durchgeführt. Die Intermediärphasen wurden durch chemische Analyse und Röntgentechnik identifiziert. Eisen(II)sulfat Heptahydrat wird in Tetrahydrat und Monohydrat überführt, doch wird diese Umwandlung durch eine Oxidation begleitet. Fe(OH)SO4 und Fe2O(SO4)2 werden als Oxidationsprodukte gebildet und letzteres wird unmittelbar und/oder über Fe2(SO4)3 zu Eisen(III)oxid zersetzt.
Résumé La décomposition thermique dans l'air du sulfate de fer(II) heptahydraté a été étudiée en conditions dynamiques et isothermes. Les phases intermédiaires ont été identifiées par analyse chimique et par rayons X. Le sulfate de fer(II) heptahydraté se transforme en tétrahydrate et en monohydrate mais cette conversion s'accompagne d'une oxydation. Il se forme Fe(OH)SO4 et Fe2O(SO4)2 comme produits d'oxydation et ce dernier se décompose en oxyde de fer(III) directement ou quelquefois avec formation intermédiaire de Fe2(SO4)3.
(II) . . (II) . Fe(OH)SO4 Fe2O(SO4)2. (III) Fe2(SO4)3.
The authors express their grateful thanks to Prof. P. K. Jena, Director, for his keen interest and permission to publish the paper, and to Dr. A. Lakshminarayana for the X-ray measurements. One of us (MSRS) also thanks the Regional Research Laboratory (CSIR) for a fellowship. 相似文献
152.
Satish Kumar N Kommana P Vittal JJ Kumara Swamy KC 《The Journal of organic chemistry》2002,67(19):6653-6658
Diisopropyl azodicarboxylate (DIAD) undergoes a cycloaddition reaction with the cyclic phosphites CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)PX (1) [X = NCS (a), N(3) (b), Cl (c), NHMe (d) and Ph (e)] to afford the novel pentacoordinate phosphoranes 2a-e as crystalline solids. This result is different from the reaction of PPh(3) with DIAD used in the well-known Mitsunobu reaction. X-ray crystallography of 2a, 2b, and 2d reveals that the nitrogen, rather than the oxygen, occupies an apical position of the trigonal bipyramidal phosphorus. This is in violation of the commonly accepted preferences for substituents in trigonal bipyramidal phosphorus. In 2e, although the oxygen of the five-membered ring occupies the expected apical position, the phenyl group also occupies (the other) apical position, forcing the more electronegative oxygen atoms of the eight-membered ring to span equatorial-equatorial positions. In contrast to the above, the isocyanato compound CH(2)(6-t-Bu-4-Me-C(6)H(2)O)(2)PNCO (1f), upon treatment with DIAD, affords compound 3 to which a tetracoordinate structure is assigned. 相似文献
153.
Reaction of the cyclodiphosphazane [(OC4H8N)P(μ‐N‐t‐Bu)2P(HN‐t‐Bu)] ( 1 ) with an equimolar quantity of diisopropyl azodicarboxylate afforded the phosphinimine product [(OC4H8N)P(μ‐N‐t‐Bu)2P=N‐t‐Bu)(N(CO2 ‐i‐Pr)NHCO2‐i‐Pr] ( 6 ) having a PIII‐N‐PV skeleton. Similar products [(t‐BuNH)P(μ‐N‐t‐Bu)2P=N‐t‐Bu)(N(CO2Et)NHCO2Et] ( 7 ) and [(CO2‐i‐Pr)HNN(CO2‐i‐Pr)](t‐BuN=P(μ‐N‐t‐Bu)2POCH2CMe2CH2O[P(μ‐N‐t‐Bu)2P=N‐t‐Bu)(N(CO2‐i‐Pr)NH(CO2‐i‐Pr)] ( 8 ) were spectroscopically characterized in the reaction of [(t‐BuNH)P‐N‐t‐Bu]2 ( 2 ) and [(t‐BuNH)P(μ‐N‐t‐Bu)2POCH2CMe2CH2OP(μ‐N‐t‐Bu)2P(NH‐t‐Bu)] ( 3 ) with diethyl‐ and diisopropyl azodicarboxylate, respectively. By contrast, the reaction of [(μ‐t‐BuN)P]2[O‐6‐t‐Bu‐4‐Me‐C6H2]2CH2 ( 4 ) and [(C5H10N)P‐μ‐N‐t‐Bu]2 ( 5 ) with diisopropyl azodicarboxylate afforded the mono‐ and bis‐oxidized compounds [(O)P(μ‐N‐t‐Bu)2P][O‐6‐t‐Bu‐4‐Me‐C6H2]2CH2 ( 9 ) and [(C5H10N)(O)P‐μ‐N‐t‐Bu]2 ( 10 ), respectively. Oxidative addition of o‐chloranil to 7 and its DIAD analogue [(t‐BuNH)P(μ‐N‐t‐Bu)2P=N‐t‐Bu)(N(CO2‐i‐Pr)NHCO2‐i‐Pr] ( 11 ) afforded [(C6Cl4‐1, 2‐O2)(t‐BuNH)P(μ‐N‐t‐Bu)2P=N‐t‐Bu)(N(CO2R)NHCO2R] [R = Et ( 12 ) and i‐Pr ( 13 )] containing tetra‐ and pentacoordinate PV atoms in the cyclodiphosphazane ring. The structures of 6 , 9 , 12 and 13 have been confirmed by X‐ray structure determination. For comparison, the X‐ray structure of the double cycloaddition product [(C6Cl4‐1, 2‐O2)(t‐BuNH)PN‐t‐Bu]2 ( 14 ), obtained from the reaction of 2 with two mole equivalents of o‐chloranil is also reported. 相似文献
154.
K. Ravikumar K. Chandra Mohan M. Bidyasagar G. Y. S. K. Swamy 《Journal of chemical crystallography》1995,25(6):325-329
Delocalization of the imidazole electron density is observed in both structures. In the dichlorocobalt complex structure, the two crystallographically independent mercaptobenzimidazole molecules are attached together through the direct bonding of the Co(II) ion with two S atoms. The cohesion of the molecules in the crystals is due to intermolecular N–H...S, and; intra and intermolecular N–H...Cl hydrogen bonds, respectively. 相似文献
155.
B. S. Sherigara B. E. Kumara Swamy E. V. S. Subrahmanyam K. Ishwar Bhat 《国际化学动力学杂志》2001,33(8):449-457
Manganese(III) (Mn(III)) has been stabilized in weakly acidic solution by means of pyrophosphate and the nature of the complex was elucidated spectrophotometrically. Stoichiometry of Mn(III)‐oxidation of levodopa and methyl dopa in pyrophosphate medium was established in the pH range 2.5–4.0 by iodometric and spectrophotometric methods. The reaction shows a distinct variation in kinetic order with respect to [Mn(III)], a first‐order dependence in the pH range 1.9–2.6, decreasing to fractional order above pH 3. Other common features include first‐order dependence on [dopa], positive fractional order dependence on [H+], and inverse first‐order dependence on [Mn(III)] in the pH range studied. The effects of varying ionic strength and solvent composition were studied. Added ions such as SO42? and ClO4? alter the reaction rate, probably due to the change in the formal redox potential of Mn(III)–Mn(II) couple because of the changes in coordination environment of the oxidizing species. Evidence for the transient existence of the free radical intermediate is given. Cyclic voltametric sensing of levodopa and methyl dopa has ruled out the formation of dopaquinones as oxidation products in the pH range studied. Activation parameters have been evaluated using the Arrhenius and Erying plots. Mechanisms consistent with the kinetic data have been proposed and discussed. These studies are expected to throw some light on dopa metabolism. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 449–457, 2001 相似文献
156.
J.S. Yadav B.V. Subba Reddy D. Narasimha Chary Ch. Suresh Reddy 《Tetrahedron letters》2008,49(16):2649-2652
Glycosyl azides, prepared in situ from glucal and trimethylsilyl azide via Ferrier rearrangement, undergo smooth coupling with alkynes under neutral conditions by means of ‘Click reactions’ to furnish 1,2,3-triazole-linked glycoconjugates in high yields and with moderate stereoselectivity. The method provides a convenient route to prepare glycoconjugates from glucals, trimethylsilyl azide, and alkynes via a three component reaction. 相似文献
157.
V. Balasubramanyam Achari T. J. R. Reddy A. K. Sharma V. V. R. Narasimha Rao 《Ionics》2007,13(5):349-354
Ion-conducting solid polymer blend electrolytes based on polyvinyl chloride (PVC)/poly methyl methacrylate (PMMA) complexed
with sodium perchlorate (NaClO4) were prepared in various concentrations by solution cast technique. The features of complexation of the electrolytes were
studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. DC conductivity of the films was measured
in the temperature range 303–398 K. Transference number measurements were carried out to investigate the nature of charge
transport in the polymer blend electrolyte system. The electrical conductivity increased with increasing dopant concentration,
which is attributed to the formation of charge transfer complexes. The polymer complexes exhibited Arrhenius type dependence
of conductivity with temperature. In the temperature range studied, two regions with different activation energies were observed.
Transference number data showed that the charge transport in this system is predominantly due to ions. Optical properties
like absorption edge, direct band gap, and indirect band gap were estimated for pure and doped films from their optical absorption
spectra in the wavelength region 200–600 nm. It was found that the energy gap and band edge values shifted to lower energies
on doping with NaClO4 salt.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamil Nadu, India, Dec. 7–9,
2006. 相似文献
158.
Bioleaching with ultrasound 总被引:5,自引:0,他引:5
Application of bioleaching of metals in a large-scale operation is reviewed briefly. Continued technical innovation is vital for the wider utilisation of this extraction process within the mineral industries. Therefore, the use of power ultrasound in combination with bioleaching (referred to as sonobioleaching) has been studied and is shown to be beneficial in the recovery of nickel from lean grade ores. The role of ultrasound in improving the benefits and lowering the drawbacks of bioleaching to an acceptable level are described. A possible mechanism for improving and intensifying this process is hypothesised. 相似文献
159.
The concept of a pseudo-complementation * on an almost distributive lattice (ADL) with 0 is introduced and it is proved that it is equationally definable. A one-to-one correspondence between the pseudo-complementations on an ADL L with 0 and maximal elements of L is obtained. It is also proved that L* = {a*|a L} is a Boolean algebra which is independent (upto isomorphism) of the pseudo-complementation * on L.AMS Subject Classification (1991): 06D99 06D15 相似文献
160.