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171.
Treatment of fac-[Rh(aet) 3] (aet = 2-aminoethanethiolate) with 2,2'-bis(bromomethyl)-1,1'-biphenyl gave a mononuclear rhodium(III) complex with a nine-membered S, S-chelate ring, fac-[Rh(aet)(L)] (2+) ([ 1] (2+), L = 2,2'-bis(2-aminoethylthiomethyl)-1,1'-biphenyl). Complex [ 1] (2+) afforded a pair of atrop diastereomers, Delta SS( S ax)/Lambda RR( R ax)-[ 1] (2+) ([ 1a] (2+)) and Delta SS( R ax)/Lambda RR( S ax)-[ 1] (2+) ([ 1b] (2+)), which involves the axial chirality ( R ax/ S ax) about a biphenyl moiety of L, besides the central chirality (Delta/Lambda) about a Rh (III) ion bound by two asymmetric ( R/ S) thioether donors. The atrop diastereomers ([ 1a] (2+) and [ 1b] (2+)) were successfully separated, isolated, and optically resolved, and the circular dichroism (CD) contribution from the axial chirality was evaluated by CD spectral analyses. 相似文献
172.
Chang L Miyata Y Ung PM Bertelsen EB McQuade TJ Carlson HA Zuiderweg ER Gestwicki JE 《Chemistry & biology》2011,18(2):210-221
DnaK is a molecular chaperone responsible for multiple aspects of bacterial proteostasis. The intrinsically slow ATPase activity of DnaK is stimulated by its co-chaperone, DnaJ, and these proteins often work in concert. To identify inhibitors we screened plant-derived extracts against a reconstituted mixture of DnaK and DnaJ. This approach resulted in the identification of flavonoids, including myricetin, which inhibited activity by up to 75%. Interestingly, myricetin prevented DnaJ-mediated stimulation of ATPase activity, with minimal impact on either DnaK's intrinsic turnover rate or its stimulation by another co-chaperone, GrpE. Using NMR, we found that myricetin binds DnaK at an unanticipated site between the IB and IIB subdomains and that it allosterically blocked binding of DnaK to DnaJ. Together, these results highlight a "gray box" screening approach, which might facilitate the identification of inhibitors of other protein-protein interactions. 相似文献
173.
Akihiro Yoshinari Akira Tazawa Prof. Dr. Shigeki Kuwata Prof. Dr. Takao Ikariya 《化学:亚洲杂志》2012,7(6):1417-1425
A new metal–ligand bifunctional, pincer‐type ruthenium complex [RuCl( L1‐H2 )(PPh3)2]Cl ( 1 ; L1‐H2 =2,6‐bis(5‐tert‐butyl‐1H‐pyrazol‐3‐yl)pyridine) featuring two proton‐delivering pyrazole arms has been synthesized. Complex 1 , derived from [RuCl2(PPh3)3] with L1‐H2 , underwent reversible deprotonation with potassium carbonate to afford the pyrazolato–pyrazole complex [RuCl(L1‐H)(PPh3)2] ( 2 ). Further deprotonation of 1 and 2 with potassium hexamethyldisilazide in methanol resulted in the formation of the bis(pyrazolato) complex [Ru(L1)(MeOH)(PPh3)2] ( 3 ). Complex 3 smoothly reacted with dioxygen and dinitrogen to give the side‐on peroxo complex [Ru(L1)(O2)(PPh3)2] ( 4 ) and end‐on dinitrogen complex [Ru(L1)(N2)(PPh3)2] ( 5 ), respectively. On the other hand, the reaction of [RuCl2(PPh3)3] with less hindered 2,6‐di(1H‐pyrazol‐3‐yl)pyridine ( L3‐H2 ) led to the formation of the dinuclear complex [{RuCl2(PPh3)2}2(μ2‐ L3‐H2 )2] ( 6 ), in which the pyrazole‐based ligand adopted a tautomeric form different from L1‐H2 in 1 and the central pyridine remained uncoordinated. The detailed structures of 1 , 2 , 3 , 3.MeOH , 4 , 5 , 6 were determined by X‐ray crystallography. 相似文献
174.
Toshihide Maejima Yutaka Shimoda Kei Nozaki Shigeki Mori Yoshinari Sawama Yasunari Monguchi Hironao Sajiki 《Tetrahedron》2012,68(6):1712-1722
An efficient copper-mediated C–N coupling reaction between various aryl halides and azido compounds to produce the corresponding aromatic primary amines was established. The present amination is apparently involved in both the reduction of an azido functionality to the corresponding primary amino group and its cross-coupling reaction with aryl halides in a one-pot manner. The present amination could be applied to the synthesis of procaine, a local anesthetic drug. A mechanistic study indicated that 2-aminoethanol could work as a major hydrogen donor and the reaction would proceed without the formation of the intermediary aryl azide. 相似文献
175.
Phase identification based on nondestructive analytical techniques using portable equipment is ideal for the analysis of art
and archaeological objects. Portable(p)-XRF and p-Raman are very widely used for this purpose, yet p-XRD is relatively rare
despite its importance for the analysis of crystalline materials. This paper overviews 6 types of p-XRD systems developed
for analysis of art and archaeological materials. The characteristics of each system are compared. One of the p-XRD systems
developed by the authors was brought to many museums as well as many archeological sites in Egypt and Syria to characterize
the cultural heritage artifacts, e.g., amulet made of Egyptian blue, blue painted pottery, and Islamic pottery from Egypt,
jade from China, variscite from Syria, a Japanese classic painting drawn by Korin Ogata, and oil paintings drawn by Taro Okamoto.
Practical application data are shown to demonstrate the potential ability of the method for analysis of various art and archaeological
materials. 相似文献
176.
Biaryl Synthesis by Ring‐Opening Friedel–Crafts Arylation of 1,4‐Epoxy‐1,4‐dihydronaphthalenes Catalyzed by Iron Trichloride 下载免费PDF全文
Dr. Yoshinari Sawama Shota Asai Takahiro Kawajiri Dr. Yasunari Monguchi Prof. Dr. Hironao Sajiki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(5):2222-2229
Biaryl and heterobiaryl compounds are important frameworks across a range of fields including pharmaceutical and functional material chemistries. We have accomplished the efficient synthesis of various naphthalene‐linked arenes and heteroarenes as biaryls and heterobiaryls by the FeCl3‐catalyzed Friedel‐Crafts reactions accompanied by the ring‐opening of the 1,4‐epoxy moiety of 1,4‐epoxy‐1,4‐dihydronaphthalenes. Especially, it is noteworthy that 1‐silylated substrates were regioselectively transformed to the 3‐aryl‐1‐silylnaphthalenes and the double Friedel–Crafts reactions using thiophene derivatives could directly produce the corresponding bis‐naphthlated thiophene derivatives. 相似文献
177.