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41.
The complexes trans-[PdCl{(ME)=NR'} (PPh3)2] (R=C6H11,p-C6H4OMe; R=p-C6H4OMe, Me) containing a σ-bonded 1,4-diaza-3-menthyl-butadiene-2-yl group with different substituents on the nitrogen atoms have been prepared by two routes. The first involves initial methylation of the mixed isonitrile complex [PdCl2(CNR)(CNR')]by HgMe2, followed by reaction with PPh3 (molar ratio ). The second method involves condensation of primary aliphatic amines with the carbonyl group of the 1-azabut-1-en-3-one-2-yl moiety of the complex trans-[PdCl{(Me) = 0} (PPh3)2]. The 1,4-diaza-3-methylbutadiene-2-yl derivatives act through their imino nitrogen atoms as chelating ligands towards anhydrous metal chlorides MCl2 (M = Co, Ni, Cu, Zn). Magnetic moment measurements and the far-infrared and electronic spectra of these adducts indicate an essentially pseudo-tetrahedral configuration at M in the solid and in solution. With the ZnCl2 adducts, the 1H NMR pattern for the phenyl protons of the p-methoxyphenyl N-substituents dependss upon the position of the substituent i the 1,4-diazabutadiene chain. 相似文献
42.
Capillary sodium dodecyl sulfate (SDS)-DALT electrophoresis (SDS-DALT-CE) refers to CE separation of proteins based on their size; DALT is the abbreviation for Dalton, the unit used to describe molecular weight. In this work, seven proteins from 18 to 116 kDa were denatured by SDS, labeled by 3-(2-furoyl) quinoline-2-carboxaldehyde, separated by SDS-DALT-CE in polyethylene oxide sieving matrix, and detected by laser-induced fluorescence (LIF) in a sheath flow cuvette. This method was combined with detergent differential fractionation, which is a protein fractionation method using a series of detergent-containing buffers to sequentially extract protein fractions from cells, to analyze the proteins in HT29 human colon adenocarcinoma cells. In addition, on-column labeling was demonstrated for protein analysis by SDS-DALT-CE with LIF, and applied to analysis of proteins in a single HT29 cancer cell. Most proteins had molecular masses from 10 to 120 kDa. Similar protein profiles were obtained for single cells and protein extract of a large cell population. 相似文献
43.
A tetra L-prolinylmethyl derivative of a tetra-sulfonated calix[4]resorcarene (1) is an effective chiral NMR solvating agent for water-soluble compounds with phenyl, pyridyl, bicyclic aromatic, or indole rings. These aromatic compounds form host-guest complexes with the calix[4]resorcarene in water. Complexation of substrates with the calix[4]resorcarene is likely promoted by hydrophobic effects, and bicyclic substrates have association constants with the calix[4]resorcarene larger than those of similar phenyl-containing compounds. Aromatic resonances of the substrates show substantial upfield shifts because of shielding from the aromatic rings of the calix[4]resorcarene, and several resonances in the 1H NMR spectra typically exhibit enantiomeric discrimination. The extent of enantiomeric discrimination depends in part on interactions of the substituent groups of the substrates with the prolinylmethyl groups of the calix[4]resorcarene. The effectiveness of a calix[4]resorcarene prepared from N-methyl-L-alanine (2) as a chiral NMR discriminating agent is compared to the L-prolinylmethyl derivative. 相似文献
44.
Summary We compare two methods (Mulliken charges and a distributed multipole analysis, DMA) of representing an ab initio charge distribution for calculating the electrostatic field and potential outside the molecule, using pyrimidine and the RNA base uracil as examples. This is done using a 3-D graphical display of the electrostatic fields, which, when used with real-time rotation, zooming and clipping, has many advantages for qualitatively assessing the electrostatic interactions of a molecule. The errors involved in using Mulliken point charges may be of similar magnitude to the total electrostatic field in regions which are important in recognition processes. The DMA representation automatically includes the anisotropic electrostatic effects of non-spherical features in the charge distribution of each atom, and yet the displayed electrostatic fields around the atoms which have lone-pair density do not show marked anisotropy. 相似文献
45.
Summary Treatment oftrans-[Mo(CNMe)2(PMe2Ph)4] andme-[W(CNMe)3(PMe2Ph)3] with sulphuric or hydrochloric acids in methanol or ethanol, or in methanol alone, under irradiation, gives methylamine, ammonia and hydrocarbons (mainly methane). The complex [W2(CNMe)4(-CNHMe)2(PMe2Ph)4]2+ cation has been obtained by the treatment ofmer-[W(CNMe)3(PMe2Ph3] with H2SO4 or [Et2OH][BF4] and gives methylamine, ammonia and methane on further acid treatment. 相似文献
46.
Bilirubin IX-α has a large extinction coefficient but shows a weak blue-shift in solvents of increasing dielectric constant. A blue-shift is typical of an n → π* transition, and is here interpreted in terms of the amide group present in the terminal pyrrole rings. Compounds undergoing n → π* transitions usually form triplet states. With bilirubin, an emission is observed at 77 K; evidence is presented that this may be phosphorescence from an excited triplet state. The energy of this triplet level is 230 kJ mole?1, thus bilirubin should be capable of sensitizing the formation of 1Δg O2. 相似文献
47.
The inactive, nitrosyl bound form of Fe-type nitrile hydratase (NHase) contains two active site cysteine residues that are post-translationally modified to sulfenate (SO-) and sulfinate (SO2-) ligands. DFT and INDO/S calculations support the hypothesis that these unusual modifications play a key role in modulating the electronic absorption spectra and photoreactivity of the Fe(III) centre in the enzyme. 相似文献
48.
P. Richards T. Prach S. C. Srivastava G. E. Meinken 《Journal of Radioanalytical and Nuclear Chemistry》1981,65(1-2):47-50
Preliminary results are described of a123Xe filled device to serve as a combination123I generator/iodination kit.123X was produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction127I(p, 5n)123Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which was crimped
a multi-injection type septum. The ampoule contained a hydrogen sulfide atmosphere to assure that the iodine generated from
the decay of the xenon was in the form of iodide. Following an adequate period for123Xe to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases
are pumped off. The123I in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device
to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been
promising.
This research was supported by the US Department of Energy under Contract No. DE-ACO2-76CH0016. 相似文献
49.
The reactions of indium(III) chloride tetrahydrate with pyrazine (C4H4N2) and pyrazine, 2-carboxylic acid afford two polymeric frameworks, the structures of which were characterized in the solid state by single crystal analysis. The former is a one-dimensional infinite structure interlinked by the pyrazine spacer, while the latter is a one-dimensional ‘zigzag’ polymeric structure. A dimeric indium(III) pyrazine complex is also reported. 相似文献
50.
Anthony B. Cornwell Philip G. Harrison John A. Richards 《Journal of organometallic chemistry》1977,140(3):273-287
The reaction of organotin chlorides with the lithium salt of 7,7,8,8-tetracyanoquinodimethane (TCNQ) or hexaalkylditins with TCNQ yield stable organotin-substituted free radicals of the types R3SnTCNQ. (R = Me, n-Pr, n-Bu) and Me2Sn(TCNQ.)2. The reaction of hexaphenylditin with TCNQ yields a (σ → π) charge transfer complex of stoichiometry (Ph3SnSnPh3)·TCNQ, whilst [Me2SnCl(terpyridyl)+](TCNQ-·) was isolated from the reaction of [Me2SnCl(terpyridlyl)+][Me2SnCl3-] and LiTCNQ. The oxidation of hexaalkylditins by tetracyanoethylene (TCNE) yields stable free radicals of the type R3SnTCNE·, but treatment with 2,3,5,6-tetrachlorobenzoquinone yields either R3SnOC6Cl4O·-p (R = Me) or R3SnOC6Cl4OSnR3-p (R = n-Bu, Ph). Tin-119 Mössbauer spectroscopy shows that the derivatives R3SnTCNQ· and R3TCNE· have trigonally-bipyramidally coordinated tin with planar [SnC3] skeletons and bridging [TCNQ·] and [TCNE·] groups forming infinite one-dimensional chain structures. Me3SnOC6Cl4O·-p was inferred to possess a similar structure but with oxy bridges forming chains with a Sn---O---Sn---O backbone. Me2Sn(TCNQ·)2 has a structure intermediate between tetrahedral and octahedral with a non-linear MeSnMe unit and anisobidentate chelation by two TCNQ groups. The TCNQ derivatives were of two types: (i) “green” or “brown”, indicative of delocalisation of the Ione electron over the cyanoquinone ligand, and (ii) a “blue” form in which spin-pairing of the Ione electron between adjacent organic groups takes place. Me3SnTCNQ· may exist in both forms depending upon the mode of preparation. 相似文献