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91.
1-Alkyl-2-(naphthyl-α/β-azo)imidazole (α-NaiR 1; β-NaiR, 2) react with [Os(H)(Cl)(CO)(PPh3)3] in THF and synthesise [Os(H)(CO)(PPh3)2(α/β-NaiR)](PF6) (3, 4). The X-ray structure of [Os(H)(CO)(PPh3)2(α-NaiEt)](PF6) (3c) shows a distorted octahedral geometry. Other spectroscopic studies (IR, UV–Vis, NMR) support the stereochemistry of the complexes. Addition of Cl2 in MeCN to 3 or 4 gives [Os(Cl)(CO)(α/β-NaiR)(PPh3)2](PF6) (5, 6), which were characterized by spectroscopic studies. The redox properties of the complexes show Os(III)/Os(II), Os(IV)/Os(III) and azo reductions. 相似文献
92.
The nature of the 7-substituent has a remarkable effect on the diastereoselectivity of the oxidative rearrangement of indole-2-carboxamides derived from (S)-2-methoxymethylpyrrolidine into chiral 3,3-disubstituted oxindoles. 相似文献
93.
Stephen M. Aucott Heather L. Milton Stuart D. Robertson Alexandra M. Z. Slawin J. Derek Woollins 《Heteroatom Chemistry》2004,15(7):530-542
The molecular structures of naphtho[1,8‐cd][1,2]dithiole, naphtho[1,8‐cd][1,2]diselenole, naphtho[1,8‐cd][1,2]ditellurole, naphtho[1,8‐cd]‐ [1,2]dithiole 1‐oxide, naphtho[1,8‐cd][1,2]dithiole 1,1‐dioxide, and naphtho[1,8‐cd][1,2]dithiole 1,1,2‐trioxideand naphtho[1,8‐cd][1,2]dithiole 1,1,2,2‐tetroxide are compared. The E–E distance varies, broadly reflecting the degree of distortion imposed by the rigid naphthalene backbone as well as the degree of oxidation at sulfur. Index Entry: The naphthalene backbone imposes shortening of E–E bond lengths when E = S and Se compared to Ph E E Ph systems but is itself subject to distortion as a consequence of the steric bulk of the E atoms. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:530–542, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20055 相似文献
94.
Tuan Q. Ly Alexandra M. Z. Slawin J. Derek Woollins 《Angewandte Chemie (International ed. in English)》1998,37(18):2501-2502
A ladder of alternating K2S2 and K2O2 rings exists in K[Ph2P(S)NC(O)Ph]⋅MeOH, the first six-membered “true” heterocycle, in the solid state (see picture). A simple P–N bond-forming reaction between benzamide and Ph2PCl gives the precursor Ph2P(S)NHC(O)Ph, from which the potassium salt can be generated by reaction with KOtBu. 相似文献
95.
96.
Dr. Ricardo Callejo Dr. Michael J. Corr Mingyan Yang Prof. Mingan Wang Dr. David B. Cordes Prof. Alexandra M. Z. Slawin Prof. David O'Hagan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8137-8151
The difluoromethylene (CF2) group has a strong tendency to adopt corner over edge locations in aliphatic macrocycles. In this study, the CF2 group has been introduced into musk relevant macrocyclic ketones. Nine civetone and five muscone analogues have been prepared by synthesis for structure and odour comparisons. X‐ray studies indeed show that the CF2 groups influence ring structure and they give some insight into the preferred ring conformations, triggering a musk odour as determined in a professional perfumery environment. The historical conformational model of Bersuker and co‐workers for musk fragrance generally holds, and structures that become distorted from this consensus, by the particular placement of the CF2 groups, lose their musk fragrance and become less pleasant. 相似文献
97.
98.
Bowman WR Burchell CJ Kilian P Slawin AM Wormald P Woollins JD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(24):6366-6381
The synthesis and full characterisation of a series of 1,2,4-thiadiazoles is reported. (SCN)(x) has been studied by a variety of techniques and the data compared with 1,2,4-thiadiazole and 1,2,4-dithiazoles. The observed data suggest that the polymer consists of 1,2,4-dithiazole rings linked by nitrogen atoms. For (SCN)(x), the MALDI-TOF mass spectroscopy showed a parent ion at 1149 and a series of peaks with (SCN)(2) repeat units (116 m/z); this result implies that (SCN)(2) may be the monomer unit of the polymer. Its IR spectrum shows a very broad peak with maximum at 1134 cm(-1) consisting of several overlapping peaks in the same region as ring vibrations for 1,2,4-thiadiazole and 1,2,4-dithiazole compounds. Peaks in the Raman spectrum in the range 400-480 cm(-1) support the presence of disulfide units within the polymer. The solid-state (13)C NMR (99 % (13)C-labelled) spectrum is dominated by two singlets of equal intensity at approximately 187 and 184 ppm with low intensity peaks in the range 152-172 ppm, in approximately the same range as both 1,2,4-thiadiazoles and 1,2,4-dithiazoles. The solid-state (15)N NMR (99 % (15)N labelled) spectrum displays two major peaks of similar intensity at 236.9 and 197.2 ppm, which are clearly very different environments to those observed in bis(3-bromo-1,2,4-thiadiazol-5-yl) disulfide, but similar to 1,2,4-dithiazoles. The X-ray structures of seven C-S-N systems are reported. Preliminary studies on (SeCN)(x) suggest that literature references to this polymer may be in error with the red solid actually being red selenium. 相似文献
99.
100.
Chia PW Livesey MR Slawin AM van Mourik T Wyllie DJ O'Hagan D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(28):8813-8819
N-Methyl-D-aspartate (NMDA) is the prototypical agonist of the NMDA receptor subtype of ionotropic glutamate receptors. Stereogenic placement of a C-F bond at the 3-position of (S)-NMDA generates either the (2S,3S)- or (2S,3R)- diastereoisomers of 3F-NMDA. The individual diastereoisomers were prepared by synthesis in enantiomerically pure forms and it was found that (2S,3S)-3F-NMDA is an agonist with a comparable potency to NMDA itself, whereas the (2S,3R)-diastereoisomer has negligible potency. The difference in potency of these stereoisomers is attributed to a preference of the C-F bond (2S,3S)-3F-NMDA to adopt a gauche conformation to the C-N(+) bond in the binding conformation, whereas the (2S,3R)-3F-NMDA forces these bonds anti, losing electrostatic stabilisation, to achieve the required binding conformation. These observations illustrate the utility of stereoselective fluorination in influencing the molecular conformation of β-fluorinated amino acids and thus probing the active conformations of bioactive compounds at receptors. 相似文献