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751.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
752.
Dr. Asfandyar Sikandar Dr. Alexander Popoff Dr. Ravindra P. Jumde Dr. Attila Mándi Dr. Amninder Kaur Dr. Walid A. M. Elgaher Dr. Lara Rosenberger Dr. Stephan Hüttel Dr. Rolf Jansen Dr. Maja Hunter Prof. Dr. Jesko Köhnke Prof. Dr. Anna K. H. Hirsch Prof. Dr. Tibor Kurtán Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2023,62(40):e202306437
Even with the aid of the available methods, the configurational assignment of natural products can be a challenging task that is prone to errors, and it sometimes needs to be corrected after total synthesis or single-crystal X-ray diffraction (XRD) analysis. Herein, the absolute configuration of amidochelocardin is revised using a combination of XRD, NMR spectroscopy, experimental ECD spectra, and time-dependent density-functional theory (TDDFT)-ECD calculations. As amidochelocardin was obtained via biosynthetic engineering of chelocardin, we propose the same absolute configuration for chelocardin based on the similar biosynthetic origins of the two compounds and result of TDDFT-ECD calculations. The evaluation of spectral data of two closely related analogues, 6-desmethyl-chelocardin and its semisynthetic derivative 1 , also supports this conclusion. 相似文献
753.
Péter Angyal András M. Kotschy Ádám Dudás Dr. Szilárd Varga Dr. Tibor Soós 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214096
A widely applicable, practical, and scalable synthetic method for efficient ene-type double oxidation of alkenes is reported via a two-step alkenyl thianthrenium umpolung/Kornblum-Ganem oxidation strategy. This chemo- and stereoselective procedure allows easy access to various α,β-unsaturated carbonyls that may be otherwise difficult or cumbersome to synthesize by conventional methods. For α-olefins, this metal-free transformation can be tuned according to synthetic needs to produce either the elusive (Z)-unsaturated aldehydes or their (E) counterparts. Moreover, this strategy has enabled streamlined synthesis of distinct butadienyl pheromones and kairomones. 相似文献
754.
Péter Angyal Kristóf Hegedüs Bence Balázs Mészáros Dr. János Daru Ádám Dudás Anna Rita Galambos Nariman Essmat Dr. Mahmoud Al-Khrasani Dr. Szilárd Varga Dr. Tibor Soós 《Angewandte Chemie (International ed. in English)》2023,62(35):e202303700
Mitragynine pseudoindoxyl, a kratom metabolite, has attracted increasing attention due to its favorable side effect profile as compared to conventional opioids. Herein, we describe the first enantioselective and scalable total synthesis of this natural product and its epimeric congener, speciogynine pseudoindoxyl. The characteristic spiro-5-5-6-tricyclic system of these alkaloids was formed through a protecting-group-free cascade relay process in which oxidized tryptamine and secologanin analogues were used. Furthermore, we discovered that mitragynine pseudoindoxyl acts not as a single molecular entity but as a dynamic ensemble of stereoisomers in protic environments; thus, it exhibits structural plasticity in biological systems. Accordingly, these synthetic, structural, and biological studies provide a basis for the planned design of mitragynine pseudoindoxyl analogues, which can guide the development of next-generation analgesics. 相似文献
755.
Krisztián Albitz Dr. Dániel Csókás Dr. Zoltán Dobi Prof. Imre Pápai Dr. Tibor Soós 《Angewandte Chemie (International ed. in English)》2023,62(13):e202216879
Prenylation is a ubiquitous late-stage modification in nature that often confers significantly improved bioactivity for secondary metabolites. While this lipophilic modification renders enhanced potency, the lipophilic tag(s) can diminish bioavailability and adversely alter drug transportation and metabolism. Thus, a functional-group-tolerant, mild, and selective late-stage C−H functionalization of prenyl tags would present a great potential in drug discovery programs but could also impact other fields, such as agrochemistry and chemical biology. Herein we report an exocyclic-strain-driven cross-metathesis reaction of prenyl tags, a formal double C−H oxidation protocol, that can be used for the selective late-stage derivatization of prenylated compounds and natural products. This methodology avoids the need for prefunctionalization of target molecules and affords ready access to an unprecedented library of oxo- and aza-prenylated complex molecules. Thus, in a broader context, this methodology extends late-stage functionalization beyond that available to nature. 相似文献
756.
757.
Vladimír Luke Martin Breza Tibor Plszegi Viliam Laurinc Imrich Vrbel 《Macromolecular theory and simulations》2001,10(6):592-599
The dependence of microscopic electronic non‐resonant polarizabilities (α) and second‐order hyperpolarizabilities (γ) of short oligothiophenes on the mutual torsional ring orientation was investigated by employing the time‐dependent Hartree–Fock method within the AM1 approximation. The α and γ quantities exhibit the uniform shape of the torsional dependence regardless of the mutual rings' orientations for all the systems under study (minima occur for perpendicular geometries and maxima are indicated for planar structures). The frequency dependence of γ hyperpolarizability below the first resonance frequency is fairly well evaluated in the form of a simple power series. The trends of AM1 results agree with the current theoretical treatments as well as experimental data. 相似文献