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911.
Synthesis and Metalation of Doubly o‐Phenylene‐Bridged Cyclic Bis(dipyrrin)s with Highly Bent Skeleton of Dibenzoporphyrin(2.1.2.1)
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Dr. Daiki Kuzuhara Wataru Furukawa Aya Kitashiro Prof. Dr. Naoki Aratani Prof. Dr. Hiroko Yamada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10671-10678
Facile synthesis of dibenzoporphyrins(2.1.2.1) has been successfully reported by the simple condensation reaction of o‐dipyrrolylbenzene with various aldehydes in the presence of a Lewis acid. This reaction enables the preparation of various dibenzoporphyrin(2.1.2.1) derivatives with p‐substituted phenyl groups, five‐membered heterocycles, and ethynyl groups at the meso‐positions. Dibenzoporphyrins(2.1.2.1) consist of two dipyrrin units that are connected by o‐phenylene bridges, which adopt highly bent saddle‐shaped structures; this was confirmed by X‐ray diffraction analysis. We found that dibenzoporphyrin(2.1.2.1) can be described as a 20π antiaromatic conjugated system, but practically, it is not an antiaromatic macrocycle, which we revealed by 1H NMR spectroscopy. The redox potentials had good correlations with Hammett substituent constant (σp) of the substituents at the meso‐positions. The free‐base dibenzoporphyrin(2.1.2.1) was able to form the metal complexes with nickel(II), copper(II), palladium(II), platinum(II), and tin(IV) ions. These results suggested that dibenzoporphyrin(2.1.2.1) derivatives can be utilized as novel macrocyclic dianionic tetradentate ligands for various metal ions to give complexes with varying optical and electrochemical properties. 相似文献
912.
Prof. Jun He Shengxian Cheng Prof. Zhengtao Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8654-8662
The versatile sulfur chemistry, as exemplified by the reactive yet tractable thiol group (-SH), offers unique opportunities for bypassing the obstacles in accessing stable and electroactive metal-organic frameworks. Of particular interest are recent advances in assembling MOF materials equipped with free-standing thiol functions: metal guests can be conveniently inserted to install electroactive metal-sulfur bonds, which, as crosslinks, also stabilize the host coordination net. Here the historical development of the bifunctional, two-step design embodied by the thiol-tagged MOF solids is traced, in order to highlight the underlying spirit that has driven research efforts in the past two decades. Going forward, broad new horizons are foreseen in solid-state materials synthesis, for example, arising from various sulfur-based hard-and-soft combinations, in synergy with the crystalline and modular MOF structural platform. 相似文献
913.
Redox and Acid–Base Properties of Binuclear 4‐Terphenyldithiophenolate Complexes of Nickel
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Dipl.‐Chem. Felix Koch Dr. Andreas Berkefeld Dr. Hartmut Schubert Claudius Grauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14640-14647
This work reports on the redox and acid–base properties of binuclear complexes of nickel from 1,4‐terphenyldithiophenol ligands. The results provide insight into the cooperative electronic interaction between a dinickel core and its ligand. Donor/acceptor contributions flexibly adjust to stabilize different redox states at the metals, which is relevant for redox reactions like proton reduction. Proton transfer to the [S2Ni2] core and Ni?H bond formation are kinetically favored over the thermodynamically favored yet unproductive proton transfer to ligand. 相似文献
914.
One‐Pot Tandem Diastereoselective and Enantioselective Synthesis of Functionalized Oxindole‐Fused Spiropyrazolidine Frameworks
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Liang‐Yong Mei Dr. Xiang‐Ying Tang Prof. Dr. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13136-13142
A highly efficient palladium(0)‐catalyzed asymmetric [3+2] cycloaddition using 3‐diazooxindoles serving as dipolarophiles affords functionalized pyrazolidine derivatives in an atom‐economical way. In addition, by trapping the pyrazolidine derivatives with maleimides, the corresponding spiropyrazolidine oxindoles containing multiple stereogenic centers have been obtained in high yields along with moderate to good levels of diastereoselectivity and enantioselectivity under mild conditions. Thus, a novel three‐component one‐pot tandem reaction has been developed. 相似文献
915.
Dr. Zhenbo Mo Dr. Takanori Shima Prof. Dr. Zhaomin Hou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8713-8722
Studies on N2 activation and transformation by transition metal hydride complexes are of particular interest and importance. The synthesis and diverse transformations of a dinitrogen dititanium hydride complex bearing the rigid acridane-based acriPNP-pincer ligands {[(acriPNP)Ti]2(μ2-η1:η2-N2)(μ2-H)2} are presented. This complex enabled N2 cleavage and hydrogenation even without additional H2 or other reducing agents. Furthermore, diverse transformations of the N2 unit with a variety of organometallic compounds such as ZnMe2, MgMe2, AlMe3, B(C6F5)3, PinBH, and PhSiH3 have been well established at the rigid acriPNP-ligated dititanium framework, such as reversible bonding-mode change between the end-on and side-on/end-on fashions, diborylative N=N bond cleavage, the formal insertion of two dimethylaluminum species into the N=N bond, and the formal insertion of two silylene units into the N=N bond. This work has revealed many unprecedented aspects of dinitrogen reaction chemistry. 相似文献
916.
Victoria A. Ternes Hannah A. Morgan Austin P. Lanquist Michael J. Murray Bradley M. Wile 《应用有机金属化学》2020,34(4):e5459
Herein we report the preparation of a series of Ru(II) complexes featuring α-iminopyridine ligands bearing thioether functionality (NNSR, where R = Me, CH2Ph, Ph). Metallation using [(p-cymene)RuCl]2 permits access to Ru complexes with a κ2-N,N donor set in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a κ3-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNSMe)Ru (NCMe)2Cl]Cl. The κ2-N,N-Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at modest loadings (alcohol: Ru = 20:1), using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active oxidation catalyst of those surveyed, suggesting that the thioether donor plays an active role in the catalytic cycle. 相似文献
917.
Tomasz Nienałtowski Paweł Szczepanik Paweł Małecki Dr. Dorota Czajkowska-Szczykowska Dr. Stefan Czarnocki Dr. Jolanta Pawłowska Dr. Anna Kajetanowicz Prof. Karol Grela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15708-15717
A large-scale synthesis of known Ru olefin metathesis catalyst VII featuring an unsymmetrical N-heterocyclic carbene (NHC) ligand with one 2,5-diisopropylphenyl (DIPP) and one thiophenylmethylene N-substituent is reported. The optimised procedure does not require column chromatography in any step and allows for preparation of up to 0.5 kg batches of the catalyst from simple precursors. The application profile of the obtained catalyst was studied in environmentally friendly dimethyl carbonate (DMC). Although VII exhibited low efficiency in cross-metathesis (CM) with electron-deficient partners, good to excellent results were noted for substrates featuring easy to isomerise C−C double bonds. This includes polyfunctional substrates of medicinal chemistry interest, such as analogues of psychoactive 5F-PB-22 and NM-2201 and two PDE5 inhibitors—Sildenafil and Vardenafil. Finally, a larger scale ring-closing metathesis (RCM) of a Vardenafil derivative was conducted in DMC, allowing for straightforward isolation of the expected product (23 g) in high yield and with low Ru contamination level (7.7 ppm). 相似文献
918.
Molybdenum Complexes Supported by Mixed NHC/Phosphine Ligands: Activation of N2 and Reaction With P(OMe)3 to the First Meta‐Phosphite Complex
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Christian Gradert Nadja Stucke Jan Krahmer Prof. Dr. Christian Näther Prof. Dr. Felix Tuczek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1130-1137
Molybdenum(0) dinitrogen complexes, supported by the mixed NHC/phosphine pincer ligand PCP, exhibit an extreme activation of the N2 ligand due to a very π‐electron‐rich metal center. The low thermal stability of these compounds can be increased using phosphites instead of phosphines as coligands. Through an amalgam reduction of [MoCl3(PCP)] in the presence of trimethyl phosphite and N2 the highly activated and room‐temperature stable dinitrogen complex [Mo(N2)(PCP)(P(OMe)3)2] is obtained. As a second product, the first transition metal complex containing the meta‐phosphite ligand P(O)(OMe) originates from this reaction. 相似文献
919.
Inside Back Cover: Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+) Derived from Molecular Precursors and Doped with Eu3+ Ions (Chem. Eur. J. 14/2016)
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920.
Screening of N,N‐bidentate and N,N,N‐tridentate pyridine‐based ligands in the catalytic allylic oxidation of cyclic olefins
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A variety of chiral N,N‐bidentate and N,N,N‐tridentate ligands based on the pyridine framework, namely C2‐symmetric dipyridylmethane and terpyridine, N‐(p‐toluensulfinyl)iminopyridines and two kinds of iminopyridines, has been assessed in the asymmetric copper(I)‐catalysed allylic oxidation of cyclic olefins. Catalytic activity and enantioselectivity were found to be highly dependent upon the framework of the ligands, which afforded cycloalkenyl benzoates in low to moderate yields and enantioselectivities. The best yields (up to 70%) and enantioselectivities (up to 53% enantiomeric excess) were obtained with an iminopyridine based on camphane and quinoline skeletons. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献