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51.
Introducing an In Situ Capping Strategy in Systems Biocatalysis To Access 6‐Aminohexanoic acid 下载免费PDF全文
Dr. Johann H. Sattler Dr. Michael Fuchs Dr. Francesco G. Mutti Barbara Grischek Dr. Philip Engel Dr. Jan Pfeffer Prof. Dr. John M. Woodley Prof. Dr. Wolfgang Kroutil 《Angewandte Chemie (International ed. in English)》2014,53(51):14153-14157
The combination of two cofactor self‐sufficient biocatalytic cascade modules allowed the successful transformation of cyclohexanol into the nylon‐6 monomer 6‐aminohexanoic acid at the expense of only oxygen and ammonia. A hitherto unprecedented carboxylic acid capping strategy was introduced to minimize the formation of the dead‐end intermediate 6‐hydroxyhexanoic acid. For this purpose, the precursor ε‐caprolactone was converted in aqueous medium in the presence of methanol into the corresponding methyl ester instead of the acid. Hence, it was shown for the first time that esterases—specifically horse liver esterase—can perform the selective ring‐opening of ε‐caprolactone with a clear preference for methanol over water as the nucleophile. 相似文献
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Brumbaugh J Schleifenbaum A Gasch A Sattler M Schultz C 《Journal of the American Chemical Society》2006,128(1):24-25
Cell function is regulated by complex and often interdependent networks of signaling molecules. To accurately describe these networks, it is important to monitor multiple signals in parallel. To this end, we have developed a genetically encoded, FRET-based probe that independently monitors both protein kinase A (PKA) and protein kinase C (PKC) activity in vivo. Artificial as well as physiological stimulants produced a negative or positive change in FRET efficiency following PKA or PKC activation, respectively. Mutations of the phosphate-accepting amino acids of the PKC substrate yielded a probe that was sensitive to PKA activation alone. 相似文献
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Reactions of tBu2P? P?P(Br)tBu2 with Phosphanes A Route to Variously Substituted Phosphinophosphinidene-phosphoranes tBu2P? P?P(Br)tBu2 1 reacts with PR3 [R3 = Et3, tBu3, Ph3, (NMe2)3, (NEt2)3, (NEt2)2Me, Me2SiMe3] according to tBu2P? P?P(Br)tBu2 + PR3 → tBu2P? P?PR3 + tBu2PBr While 1 decomposes above ?30°C yielding tBu2PBr and the cyclophosphanes (tBu2P)3P3 and (tBu2P)4P4, there is no condensation to give any cyclophosphanes from the intermediately formed tBu2P? P in the presence of PR3. The chlorophosphanes tBu2PCl, tBuPPhCl, (Et2N)2PCl and Ph2PCl as well as (CF3)2PBr react quite analogously to the above equation yielding tBu2P? P?P(Cl)tBu2, tBu2P? P?PtBuPhCl, tBu2P? P?P(NEt2)2Cl and tBu2P? P?P(NEt2)2Br. 相似文献
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U. Müller K. Sattler J. Xhie N. Venkateswaran G. Raina 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,19(4):319-321
We report a topographic study of platinum clusters on highly-oriented pyrolytic graphite (HOPG) using a scanning tunneling microscope operating in air. The particles were produced by evaporation of platinum onto the graphite-surface in high vacuum. The simultaneous finding of single platinum atoms, clusters and small particles on an otherwise clean and atomically flat surface shows that the platinum-HOPG surface interaction is strong enough to yield stable images of Pt atoms and yet is not strong enough to annihilate the Pt-Pt interaction. Small flat platinum clusters on HOPG can be imaged with atomic resolution of the cluster and the surrounding graphite lattice. We show the adsorption site distribution for the monomers. The Pt-dimers show a very broad bond length distribution on graphite with an average of 2.46 Å. We found two types of Pt-trimers, one which is almost linear and one of triangular form. The average nearest neighbour distance of the trimers is 2.61 Å. 相似文献
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Crystal Structure of Sodium Dihydrogencyamelurate Tetrahydrate Na[H2(C6N7)O3] · 4 H2O Sodium dihydrogencyamelurate‐tetrahydrate Na[H2(C6N7)O3]·4 H2O was obtained by neutralisation of an aqueous solution, previously prepared by hydrolysis of the polymer melon with sodium hydroxide. The crystal structure was solved by single‐crystal X‐ray diffraction ( a = 6.6345(13), b = 8.7107(17), c = 11.632(2) Å, α = 68.96(3), β = 87.57(3), γ = 68.24(3)°, V = 579.5(2) Å3, Z = 2, R1 = 0.0535, 2095 observed reflections, 230 parameters). Both hydrogen atoms of the dihydrogencyamelurate anion are directly bound to nitrogen atoms of the cyameluric nucleus, thus proving the preference of the keto‐tautomere in salts of cyameluric acid in the solid‐state. The compound forms a layer‐like structure with an extensive hydrogen bonding network. 相似文献
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