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171.
Marion Kieffer Rana A. Bilbeisi John D. Thoburn Jack K. Clegg Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2020,59(28):11369-11373
Two CoII4L4 tetrahedral cages prepared from similar building blocks showed contrasting host–guest properties. One cage did not bind guests, whereas the second encapsulated a series of anions, due to electronic and geometric effects. When the building blocks of both cages were present during self‐assembly, a library of five CoII LA x LB 4?x cages was formed in a statistical ratio in the absence of guests. Upon incorporation of anions able to interact preferentially with some library members, the products obtained were redistributed in favor of the best anion binders. To quantify the magnitudes of these templation effects, ESI‐MS was used to gauge the effect of each template upon library redistribution. 相似文献
172.
Redox Mechanism and Evaluation of Kinetic and Thermodynamic Parameters of 1,3‐Dioxolo[4,5‐g]pyrido[2,3‐b]quinoxaline Using Electrochemical Techniques
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Aamir Hassan Shah Afzal Shah Usman Ali Rana Salah Ud‐Din Khan Hidayat Hussain Sher Bahadar Khan Rumana Qureshi Amin Badshah 《Electroanalysis》2014,26(10):2292-2300
The electrochemical behavior of a biologically important heterocyclic compound, 1,3‐dioxolo[4,5‐g]pyrido[2,3‐b]quinoxaline was investigated by cyclic, square wave and differential pulse voltammetry in solutions of different pH. Kinetic and thermodynamic parameters like standard rate constant, diffusion coefficient, apparent energy of activation, standard Gibbs free energy and enthalpy and entropy changes were evaluated. Limits of detection and quantification were determined by square wave voltammetry. The redox mechanism of the compound was proposed on the basis of experimental results. Computational chemistry was used as a tool for the verification of experimental outcomes and assessment of different theoretical parameters 相似文献
173.
Rhodanine-based biologically active molecules: synthesis,characterization, and biological evaluation
Aniruddhasinh M. Rana Kishor R. Desai Smita Jauhari 《Research on Chemical Intermediates》2014,40(2):761-777
To investigate the antimicrobial properties of the rhodanine (2-thioxo-4-thiazolidinone) structure, several 2-[(5Z)-5-benzylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]-N-phenylacetamide derivatives were synthesized by use of an efficient procedure. Variation of the functional group on the 5-benzylidine ring of rhodanine led to compounds containing a 2-thioxo-4-thiazolidinone group attached to N-phenyl acetamide. The chemical structures of the compounds were confirmed by IR, 1H NMR, and 13C NMR spectroscopy, ESI mass spectrometry, and elemental analysis. The antibacterial and antifungal activity of the compounds were tested, at seven concentrations, against Gram-positive bacterial strains (Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922), Gram-negative bacterial strains (Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 11774), and fungal strains (Candida albicans ATCC 66027 and Aspergillus niger ATCC 6275), by use of the Kirby Bauer disk-diffusion technique and the serial broth dilution technique. The results obtained were compared with those for reference drugs. Relationships between structure and their antimicrobial activity are discussed. 相似文献
174.
Design of Leaving Groups in Radical CC Fragmentations: Through‐Bond 2c–3e Interactions in Self‐Terminating Radical Cascades
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Dr. Sayantan Mondal Brian Gold Rana K. Mohamed Prof.Dr. Igor V. Alabugin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8664-8669
Radical cascades terminated by β‐scission of exocyclic C?C bonds allow for the formation of aromatic products. Whereas β‐scission is common for weaker bonds, achieving this reactivity for carbon–carbon bonds requires careful design of radical leaving groups. It has now been found that the energetic penalty for breaking a strong σ‐bond can be compensated by the gain of aromaticity in the product and by the stabilizing two‐center, three‐electron “half‐bond” present in the radical fragment. Furthermore, through‐bond communication of a radical and a lone pair accelerates the fragmentation by selectively stabilizing the transition state. The stereoelectronic design of radical leaving groups leads to a new, convenient route to Sn‐functionalized aromatics. 相似文献
175.
Chromatographia - 2,3,4,6-tetra-O-acetyl-β-D-glucopranosyl isothiocyanate derivatives of a number of basic compounds, containing one chiral center, have been prepared. The indirect resolution... 相似文献
176.
S. S. Rana 《分析论及其应用》1990,6(4):58-64
In this paper, we have obtained a precise estimate concerning the discrete cubic spline interpolating a given function at
the mesh points.
This work was partially supported by DAAD grant 325/813/013/0. 相似文献
177.
It is shown that G-varying cosmologies provide a better fit to the observed data on cosmic microwave background, than the standard Friedmann models. 相似文献
178.
Dr. Soumen K. Samanta M. Sc. Anup Rana Prof. Dr. Michael Schmittel 《Angewandte Chemie (International ed. in English)》2016,55(6):2267-2272
Several five‐component nanorotors ROT‐3 that rotate at different rates were prepared by adding phenanthrolines of distinct lateral size as brake blocks to the four‐component nanorotor ROT‐2. The brake blocks interfere with the 180° rotor causing the rotational frequency to drop from 97 kHz to 5 kHz. The effect of the rotating brake blocks on the rotational frequency in ROT‐3 is accurately predicted by a nanomechanical model called “conformational slippage”. For quantification, the interaction of the brake blocks with the trajectory of the main rotator is gauged based on the number of interfering vs. non‐interfering conformations as computed by PM6. 相似文献
179.
Alkynes as Linchpins for the Additive Annulation of Biphenyls: Convergent Construction of Functionalized Fused Helicenes
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Dr. Rana K. Mohamed Dr. Sayantan Mondal Joseph V. Guerrera Teresa M. Eaton Prof. Thomas E. Albrecht‐Schmitt Prof. Michael Shatruk Prof. Igor V. Alabugin 《Angewandte Chemie (International ed. in English)》2016,55(39):12054-12058
A new approach to fused helicenes is reported, where varied substituents are readily incorporated in the extended aromatic frame. From the alkynyl precursor, the final helical compounds are obtained under mild conditions in a two‐step process, in which the final C?C bond is formed via a photochemical cyclization/ dehydroiodination sequence. The distortion of the π‐system from planarity leads to unusual packing in the solid state. Computational analysis reveals that substituent incorporation perturbs geometries and electronic structures of these nonplanar aromatics. 相似文献
180.
Waveband and dose dependency of sunlight-induced immunomodulation and cellular changes 总被引:1,自引:0,他引:1
Both the UVB and UVA wavebands within sunlight are immunosuppressive. This article reviews the relationship between wavebands and dose in UV-induced immunosuppression mainly concentrating on responses in humans. It also contrasts the effects of UVB and UVA on cellular changes involved in immunosuppression. Over physiological sunlight doses to which humans can be exposed during routine daily living or recreational pursuits, both UVA and UVB suppress immunity. While there is a linear dose relationship with UVB commencing at doses less than half of what is required to cause sunburn, UVA has a bell-shaped dose response over the range to which humans can be realistically exposed. At doses too low for either waveband to be suppressive, interactions between UVA and UVB augment each other, enabling immunosuppression to occur. At doses beyond where UVA is immunosuppressive, it still contributes to sunlight-induced immunosuppression via this interaction with UVB. While there is little research comparing the mechanisms by which UVB, UVA and their interactions can cause immunosuppression, it is likely that different chromophores and early molecular events are involved. There is evidence that both wavebands disrupt antigen presentation and effect T cell responses. Different individuals are likely to have different immunomodulatory responses to sunlight. 相似文献