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201.
Nowak-Król A Koszarna B Yoo SY Chromiński J Wecławski MK Lee CH Gryko DT 《The Journal of organic chemistry》2011,76(8):2627-2634
Efficient and convenient conditions for the preparation of trans-A(2)B(2)-porphyrins bearing two phenylethynyl moieties directly from phenylpropargyl aldehydes and dipyrromethanes of diversified lipophilicity and reactivity have been developed. This new procedure allows the preparation of a library of porphyrins of this architecture with a wide range of substituents. Thanks to the identification of the reagent solubility as one of the key factors influencing the yield of the porphyrinogens, we were able to improve yields to ca. 30%. The scope and limitations of two sets of conditions have been explored. The methodological advantage of this approach is its straightforward access to building blocks and the formation of the porphyrin core in the last step without the need for deprotection of the triple bond or bromination and consecutive coupling reaction, which often demands copper salts to proceed smoothly, especially with electron-deficient alkyne partners. Therefore, it prevents undesired copper porphyrin formation, as well as the need for utilizing expensive alkynes. A two-step method for the preparation of phenylpropargyl aldehydes has also been refined. 相似文献
202.
Reactions of copper(II) bromide with racemic sparteine-2-thione (SSp) in a 1:1 M ratio yielded two new complexes, whose structures depend on the solvent used. In acetonitrile, the reaction product is a sulfur-bridged dinuclear [CuBr2(μ-SSp)]2 complex (1) in which sparteine-2-thione acts as a bridging S-ligand, while in methanol it is a CuBr2 complex (2) with sparteine deprived of the A-ring. Compound 1 crystallizes as an acetonitrile solvate in a 1:2 ratio and constitutes one of a few Cu(II) doubly bridged heterocyclic thionato complexes. The disorder of the C/D bisquinolizidine fragment in the crystal of 1 reflects the ease of the conversion from the common trans boat-chair to the unprecedented cis chair-boat stereoisomer. Obtained in methanol, the sparteine surrogate (Sp(surr)), is equally effective as a chelating ligand as sparteine and its isomers, and thus can be used as an alternative diamine ligand in metal complexation. Metal coordination with Sp(surr) brings the diamine nitrogens much closer together than in any other sparteine metal complexes. 相似文献
203.
Beata Jasiewicz 《Polyhedron》2011,30(10):1703-1709
Cu[(C15H26N2)(OCOR)2] complexes, where OCO is a fragment of either formato or acetato group and C15H26N2 is sparteine or α-isosparteine have been synthesized and structurally characterized. The bis-formato complexes (1 and 2) display a distorted 4 + 1 coordination resulting from variable metal binding stereochemistry and function of the two formato units. The syn formato group acts as a pseudochelating bidentate while the anti conformer as a monodentate ligand. This inequivalence of the two formate ligands seems deliberate for it allows formation of the stabilizing intramolecular hydrogen bond between the CH donor belonging to the monodentate formate ligand and equatorially coordinated oxygen atom belonging to the pseudo-chelating formate ligand. At variance, the C2 symmetrical bis-acetato complex (3) displays tetragonally elongated octahedral geometry of the CuN2O2O′O′ with long off-axis coordination of the second O atom from each acetate ligand in the axial position.Complexes 1-3 have been also characterized by elemental analysis, IR, UV-Vis and MS spectroscopy. 相似文献
204.
Jasiewicz B Wojciechowska-Nowak M Boczoń W Wyrzykiewicz E 《European journal of mass spectrometry (Chichester, England)》2011,17(3):227-235
The electron-ionization mass spectra (EI-MS) of oxo- and thio-derivatives of minor tobacco alkaloids and structurally similar piperidine alkaloids, i.e. thiocotinine (1), 2'-oxo-N-methylanabasine (2), 2'-thio-N- methylanabasine (3), 2'-oxoanabasamine (4) and 2'-thioanabasamine (5) are discussed and general fragmentation routes of their molecular cations are proposed. Comparison of the data obtained for 1 with the EI-MS data of metameric metabolites of nicotine: 3'-hydroxycotinine, (A) and 5'-hydroxycotinine, (B) allows a differentiation between these metamers. The data will be useful for the identification of metabolites of alkaloids of these types in biological matrices. 相似文献
205.
Beata Orlińska Zbigniew Stec Jan Zawadiak 《Monatshefte für Chemie / Chemical Monthly》2012,9(4):295-301
Abstract
Aerobic oxidation of 2-methoxy-6-(1-methylethyl)naphthalene to hydroperoxide, alcohol, and ketone, is reported. These compounds, particularly 2-acetyl-6-methoxynaphthalene, are important intermediates in naproxen synthesis. N-Hydroxyphthalimide is shown here to be an efficient catalyst for oxidation to the hydroperoxide, 2-methoxy-6-(1-hydroperoxy-1-methylethyl)naphthalene, with a yield of 87%. However, the ketone and alcohol were obtained with lower yields, with a maximum yield of 13% for the ketone and 27% for the alcohol, using N-hydroxyphthalimide and Cu(II) acetylacetonate as a catalyst. The synthesis of the products 2-acetyl-6-methoxynaphthalene and 2-methoxy-6-(1-hydroxy-1-methylethyl)naphthalene via an initial oxidation step to the hydroperoxide followed by a hydroperoxide decomposition step is shown to be more efficient; the ketone and alcohol were obtained from 2-methoxy-6-(1-methylethyl)naphthalene with yields of 40 and 56%, respectively. 相似文献206.
Agnieszka Swiderska-Mocek Andrzej Lewandowski Beata Kurc 《Journal of Solid State Electrochemistry》2012,16(2):673-679
Electrochemical properties of LiNiO2|Li and LiNiO2|graphite cells were analysed in ionic liquid electrolyte [Li+][MePrPyrr+][NTf2-] (based on N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulphonyl)imide, [MePrPyrr+][NTf2-]) using impedance spectroscopy and galvanostatic techniques. The ionic liquid is incapable of protective solid electrolyte
interface (SEI) formation on metallic lithium or lithiated graphite. However, after addition of VC, the protective coating
is formed, facilitating a proper work of the Li-ion cell. Scanning electron microscopy images of pristine electrodes and those
taken after electrochemical cycling showed changes which may be interpreted as a result of SEI formation. The charging/discharging
capacity of the LiNiO2 cathode is between 195 and 170 mAh g−1, depending on the rate. The charging/discharging efficiency of the graphite anode drops after 50 cycles from an initial value
of ca. 360 mAh g−1 to stabilise at 340 mAh g−1. The replacement of a classical electrolyte in molecular liquids (cyclic carbonates) with an electrolyte based on the MePrPyrrNTf2 ionic liquid highly increases in the cathode/electrolyte non-flammability. 相似文献
207.
Agnieszka Adamczyk-Woźniak Michał K. Cyrański Beata T. Frączak Agnieszka Lewandowska Izabela D. Madura Andrzej Sporzyński 《Tetrahedron》2012,68(19):3761-3767
ortho-Iminomethylphenylboronic acids were synthesized from the reaction of 2-formyl–phenylboronic acid with primary aromatic amines. Reduction of these compounds yielded the corresponding aminomethylphenylboronic acids. For both types of the compounds, the crystal structure was determined by single crystal X-ray diffraction method. Hydrogen-bonded dimers with an additional intramolecular B–O–H…N hydrogen bond have been observed. Calculations at MP2/6–31+G** level proved that the most stable form is that with the above-mentioned intramolecular hydrogen bond while the form with dative N→B bond is less favoured. Since the calculated energy difference is small, the competition between possible forms was analyzed in terms of substituent effect stabilization energy (SESE). In the case of p-iminomethylphenylboronic acid, both hydroxyl groups are engaged in intermolecular O–H…O interactions resulting in a supramolecular ribbon motif. 相似文献
208.
209.
The ESI and FAB mass spectral fragmentations of seven bis-quinolizidine alkaloids were investigated. Fragmentation pathways, elucidation of which was assisted by FAB/CID mass spectra measurements, are discussed. The data create the basis for distinguishing stereoisomers and metamers. 相似文献
210.
Polybenzene unit BT_48 can dimerize either by identification of 8-membered rings to provide a diamond-like fcc net or by identifying the opening 12-membered rings to form intercalated dendrimer-dimers which can further grow and rather quickly superimpose over the diamond-like network. The third hypothetical moiety we consider here is an eclipsed isomer, that can form multitori as negatively curved structures of various complexity. Multitori can evolve spherically or show a linear periodicity, as in rods. The polybenzene (??armchair??) multitori BTA are compared to the (??zig-zag??) BTZ ones, proposed earlier by us. A graph-theoretical study related the structure of multitori to the genus of their embedding surface and established the lower and upper bound values of genus. The total energy per carbon atom, HOMO-LUMO gap and strain energy of BTA and BTZ multitori have been computed and the results obtained point to BTZ multitori to be at least as stable as C60 what suggests BTZ multitori can be eventually synthesized in laboratory. 相似文献