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31.
Armando J.L. Pombeiro Christopher J. Pickett Raymond L. Richards 《Journal of organometallic chemistry》1982,224(3):285-294
The isocyanide complexes trans-[ReCl(CNR)(dppe)2] (R Me, But, C6H4CH3-4, C6H4CH3-2, C6H4Cl-4, C6H4OCH3-4 and C6H3Cl2-2,6; dppe Ph2PCH2CH2PPh2) have been prepared by isocyanide displacement of dinitrogen from the parent complex trans-[ReCl(N2)(ddpe)2]. Their redox properties have been studied by cyclic voltammetry and are interpreted on the basis of the electronic properties and the geometry of the ligating isocyanides which are believed to be bent in these complexes, appearing to exhibit ligand parameter (PL) values ca. +0.3 V higher than those which would be expected for linear geometry. A very high polarisability (B ? 3.4) is observed for the {ReCl(dppe)2} site. 相似文献
32.
The Cs-Cu-Q (Q = S, Se) system has been investigated using copper metal, cesium chloride, and alkali-metal polychalcogenide salts under mild hydrothermal reaction conditions. Heteropolychalcogenide salts and mixtures of known polysulfide and polyselenide salts have been used as reagents. The reaction products contain the alpha-CsCuQ(4) and CsCuQ(6) structures. The alpha-CsCuQ(4) phase exhibits a smooth transition in lattice parameters from the pure sulfur to the pure selenium phases, based on Vegard's law. The CsCuQ(6) phase has been prepared as the pure sulfur analog and a selenium rich analog. The single-crystal structures of the disordered compounds alpha-CsCuS(2)Se(2) (P2(1)2(1)2(1), Z = 4, a = 5.439(1) ?, b = 8.878(2) ?, c = 13.762(4) ?) and CsCuS(1.6)Se(4.4) (P&onemacr;, Z = 2, a = 11.253(4) ?, b = 11.585(2) ?, c = 7.211(2) ?, alpha = 92.93 degrees, beta = 100.94 degrees, gamma = 74.51 degrees ) have been solved using a correlated-site occupancy model. These disordered structures display a polychalcogenide geometry in which the sulfur atoms prefer positions that are bound to copper. The optical absorption spectra of these materials have been investigated. The optical band gap varies as a function of the sulfur-selenium ratio. Extended Hückel crystal orbital calculations have been performed to investigate the electronic structure and bonding in these compounds in an attempt to explain the site distribution of sulfur and selenium. 相似文献
33.
Jacques Dunoguès Elisabeth Jousseaume Jean-Paul Pillot Raymond Calas 《Journal of organometallic chemistry》1973,52(2):C11-C17
The trimethylchlorosilane/magnesium/hexamethylphosphoric triamide (HMPT) system reacts with some functional polychlorinated compounds (chloral, hexachloroacetone, acetone chloroform) affording a partial reduction accompanied by silylation and leads to new functional silylated derivatives.These reactions exhibit reductive properties of magnesium, in HMPT, towards the CCl bond. 相似文献
34.
Monoanionic tridentate ligands LHa and LHb containing ONSe and ONTe donor sequences and their Pd2+ and Pt2+ derivatives were synthesized and characterized. The formation of a five- and a six-membered ring around the central metal atom and associative phenomena in solutions provide extra stability to the metal complexes. 相似文献
35.
The products of the reaction of butadiene with diethyl malonate catalysed by a palladium complex and of butadiene with acetaldehyde catalysed by a nickel(0) complex have been used in two syntheses of 3,7-dimethylpentadecan-2-ol. 相似文献
36.
37.
Klapars A Waldman JH Campos KR Jensen MS McLaughlin M Chung JY Cvetovich RJ Chen CY 《The Journal of organic chemistry》2005,70(24):10186-10189
[reaction: see text] A mild and transition-metal-free method for the alpha-arylation of aliphatic nitriles with activated heteroaryl halides was developed using NaHMDS or KHMDS as base at ambient temperature. The key to the success of this method is generation of the nitrile anion in the presence of the heteroaryl halide. The method is applicable to both primary and secondary carbonitriles and a wide range of heteroaryl halides. Selective monoarylation was observed with primary carbonitriles. The operational simplicity and the mild reaction conditions add to the value of this method as a practical alternative to the preparation of alpha-heteroaryl carbonitriles. 相似文献
38.
Nordesferriferrithiocin, NDFFTH(2), is a derivative of the siderophore desferriferrithiocin, DFFTH(2), in which the methyl group is substituted by a hydrogen atom. Both compounds show high oral activity as possible drugs for the treatment of iron overload. While DFFTH(2) is significantly toxic, NDFFTH(2) exhibits a lower toxicity and offers a much better therapeutic window than other orally active iron chelators. In this study, complexes of DFFTH(2) and NDFFTH(2) with various trivalent metals have been synthesized and characterized. Five isomers (the maximum possible) have been observed in the case of [Co(DFFT)(2)](-) in solution, as proved by (1)H-NMR measurements. Although normally labile, complexes of Al(3+) ([Al(DFFT)(2)](-)) have been separated by HPLC. In general, DFFTH(2) forms kinetically inert complexes whereas complexes of NDFFTH(2) tend to isomerize quickly in solution, as indicated by CD spectroscopy of separated HPLC fractions of [Cr(NDFFT)(2)](-). The most stable isomers of the aluminum complexes of both ligands have been characterized by X-ray crystallography; K[Al(DFFT)(2)] crystallizes from methanol/diethyl ether in the orthorhombic space group P2(1)2(1)2 with a = 11.238(3) ?, b = 31.719(11) ?, c = 7.684(2) ?, V = 2739.2(24) ?(3), and Z = 4. This isomer has the mer-(N,O-Lambda)(S,S) configuration, while K[Al(NDFFT)(2)] crystallizes from methanol/diethyl ether in the space group P6(1) (a = 21.269(8) ?, c = 9.643(3) ?, V = 3777.8(42) ?(3), Z = 6) and has the same coordination geometry. The solution thermodynamics of the Al(3+), Ga(3+), and Fe(3+) complexes have been studied by spectrophotometric titration. The stability constants (log K) are 23.6(1), 29.2(3), and 31.04(3), respectively, for the DFFTH(2) complexes and 22.0(1), 27.8(2), and 29.09(3), respectively, for the NDFFTH(2) complexes. Cyclic voltammograms of both iron complexes have been recorded in water at a carbon disk working electrode and in DMF at a graphite working electrode. The reduction waves measured in DMF indicate no reversibility whereas in water a quasi-reversible reduction is observed. The reduction potentials (E(1/2)'s) in water are -166 mV for [Fe(DFFT)(2)](-) and -97 mV for [Fe(NDFFT)(2)](-) versus NHE. These potentials are well in the range for biological reductants, which makes possible an in vivo reduction mechanism for the iron removal from the siderophore. 相似文献
39.
Conejo-García A Campos JM Entrena A Sánchez-Martín RM Gallo MA Espinosa A 《The Journal of organic chemistry》2003,68(22):8697-8699
A complete study of the conformational behavior of 4,8-diaza-3(1,4),9(4,1)-dipyridina-1,6(1,4)-dibenzenacyclodecaphan-3(1),9(1)-bis(ilium) bishexafluorophosphate is described. This study allows us to conclude that the process observed by which the different chemical shifts of the pyridinium protons show coalescence at a high-temperature 1H NMR is the rotation around the C-N bond, whereas the conformational equilibrium between the four conformers is produced at low temperature. 相似文献
40.
3-(1-Methylethyl)-7-methyl2,6-octadienal, was prepared from 1,1,3-triethoxy-3,4-dimethylpentane and 3-methyl-2-buten-l-ol in a one-pot procedure utilising Claisen and Cope rearrangement of an intermediate dienol-allyl ether. 相似文献