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731.
Clicking the Arsenic–Carbon Triple Bond: An Entry into a New Class of Arsenic Heterocycles
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Dipl.‐Chem. Gregor Pfeifer M. Sc. Martin Papke B. Sc. Daniel Frost M. Sc. Julian A. W. Sklorz M. Sc. Marija Habicht Prof. Dr. Christian Müller 《Angewandte Chemie (International ed. in English)》2016,55(39):11760-11764
Arsaalkynes can undergo regioselective and quantitative [3+2] cycloaddition reactions with organic azides to give hitherto unknown 3H‐1,2,3,4‐triazaarsole derivatives. The reaction product was obtained as a white, air‐ and moisture‐stable solid, and the presence of a planar, five‐membered arsenic heterocycle was unambiguously verified by means of X‐ray crystallography. DFT calculations gave insight into the electronic structure of these novel compounds compared to tetrazoles and triazaphospholes. The coordination chemistry towards ReI was investigated and compared with the structurally related phosphorus‐containing ligand. These preliminary investigations pave the way for a new class of arsenic heterocycles and fill the gap between the azaarsoles already known. 相似文献
732.
Alexandre Hofer Gregor S. Cremosnik André C. Müller Dr. Roberto Giambruno Dr. Claudia Trefzer Prof. Dr. Giulio Superti‐Furga Dr. Keiryn L. Bennett Prof. Dr. Henning J. Jessen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(28):10116-10122
Phosphoanhydrides (P‐anhydrides) are ubiquitously occurring modifications in nature. Nucleotides and their conjugates, for example, are among the most important building blocks and signaling molecules in cell biology. To study and manipulate their biological functions, a diverse range of analogues have been developed. Phosphate‐modified analogues have been successfully applied to study proteins that depend on these abundant cellular building blocks, but very often both the preparation and purification of these molecules are challenging. This study discloses a general access to P‐anhydrides, including different nucleotide probes, that greatly facilitates their preparation and isolation. The convenient and scalable synthesis of, for example, 18O labeled nucleoside triphosphates holds promise for future applications in phosphoproteomics. 相似文献
733.
One‐Electron Oxidation of a Disilicon(0) Compound: An Experimental and Theoretical Study of [Si2]+ Trapped by N‐Heterocyclic Carbenes
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Marius I. Arz Martin Straßmann Andreas Meyer Dr. Gregor Schnakenburg Prof. Dr. Olav Schiemann Prof. Dr. Alexander C. Filippou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12509-12516
One‐electron oxidation of the disilicon(0) compound Si2(Idipp)2 ( 1 , Idipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) with [Fe(C5Me5)2][B(ArF)4] (ArF=C6H3‐3,5‐(CF3)2) affords selectively the green radical salt [Si2(Idipp)2][B(ArF)4] ( 1 ‐[B(ArF)4). Oxidation of the centrosymmetric 1 occurs reversibly at a low redox potential (E1/2=?1.250 V vs. Fc+/Fc), and is accompanied by considerable structural changes as shown by single‐crystal X‐ray structural analysis of 1 ‐B(ArF)4. These include a shortening of the Si?Si bond, a widening of the Si‐Si‐CNHC angles, and a lowering of the symmetry, leading to a quite different conformation of the NHC substituents at the two inequivalent Si sites in 1+ . Comparative quantum chemical calculations of 1 and 1+ indicate that electron ejection occurs from the symmetric (n+) combination of the Si lone pairs (HOMO). EPR studies of 1 ‐B(ArF)4 in frozen solution verified the inequivalency of the two Si sites observed in the solid‐state, and point in agreement with the theoretical results to an almost equal distribution of the spin density over the two Si atoms, leading to quite similar 29Si hyperfine coupling tensors in 1+ . EPR studies of 1 ‐B(ArF)4 in liquid solution unraveled a topomerization with a low activation barrier that interconverts the two Si sites in 1+ . 相似文献
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736.
Gregor Zwaschka François Lapointe R. Kramer Campen Yujin Tong 《Current Opinion in Electrochemistry》2021
The essential part of electrochemistry is charge transfer. To understand this process in great detail, one needs to probe the relevant kinetics and dynamics on time scales spanning from femtoseconds to seconds or even longer. Although a conventional electrochemical detection scheme is sufficient for nanosecond or slower processes, it does not offer high enough time resolution for probing ultrafast processes, such as solvent reorganization, electron tunneling, and surface isomerization, that occur on faster, for example picosecond or femtosecond, timescales. These are indispensable parameters in the advanced charge transfer theories. In this review, some recent studies using ultrashort lasers to explore the ultrafast dynamics at the metal/solution interface are reviewed. The focus is on optical pump-probe and optical pump-push with electrochemical probe schemes. The connection of these studies with conventional electrochemistry and the limitations of these detection schemes are discussed. 相似文献
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738.
Florian G. Perrin Dr. Gregor Kiefer Loïc Jeanbourquin Sophie Racine Daniele Perrotta Prof. Jérôme Waser Dr. Rosario Scopelliti Prof. Kay Severin 《Angewandte Chemie (International ed. in English)》2015,54(45):13393-13396
The chemical reactivity of 1‐alkynyltriazenes has been investigated and is found to parallel the reactivity of ynamides. The similarity in reactivity of these two classes of compounds is demonstrated by addition reactions with acids, by cycloaddition reactions with ketenes, tetracyanoethene, and cyclopropanes, as well as by intramolecular cyclization reactions. The presence of reactive triazene groups in the products enables subsequent transformations. Overall, our results suggest that 1‐alkynyltriazenes should become valuable reagents in synthetic organic chemistry. 相似文献
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