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991.
Weihong Liang Wenhao Yin Tingzhong Wang Fayang G. Qiu Junling Zhao 《Tetrahedron letters》2018,59(18):1742-1747
A novel method for the stereoselective conjugate addition of 3-substituted oxindoles to in situ generated o-QMs was described. This process was catalyzed efficiently by a cinchonidine-derived squaramide catalyst in oil-water phase, furnishing the corresponding 3,3-disubsituted oxindole derivatives in moderate to high yields (up to 98%) with high stereoselectivities (up to 95%?ee, 15.4:1?dr). The utility of this reaction was also investigated by the gram-scale synthesis and derivatization of one of the products. 相似文献
992.
A significant number of reactions regarding hydrofunctionalization of alkynes have appeared in the literature over the years. This digest focus on the transition-metal catalyzed enantioselective alkyne hydrofunctionalization reactions. Based on the reaction mechanism, these reactions described herein are classified into three types. Strategies, substrate scope, along with mechanisms are highlighting. 相似文献
993.
Chemical differences of the extractives revealed by FTIR methods can be further confirmed by 1H NMR and 13C NMR. Meanwhile, the volatile compounds in the extractives can be identified by GC/MS 相似文献
994.
This review focuses on the progresses and challenges in the preparation of Man3GlcNAc2 (M3) which is the core structure in the N-glycan biological pathway. Representative methods and recent reported findings, especially research advances in chemoenzymatic synthesis, are highlighted. 相似文献
995.
Here we describe a convergent synthesis of reniochalistatin E that utilized solid-phase peptide synthesis. For macrolactamization of the linear peptides without the side chain protecting group, we obtained reniochalistatin E and its conformational isomers with 32% isolation yield. 相似文献
996.
997.
998.
The binding interactions of a series of 2,2′:6′,2″-terpyridine (TPY) derivatives and their metal complexes with cucurbit[10]uril (CB[10]) were investigated by 1H NMR, UV/Vis, emission spectroscopy, and ESI mass spectrometry. 1H NMR titrations revealed CB[10] could encapsulate methylated TPY (MTPY), and the binding ratio between guest MTPY and host was 1:1 and 2:1 via ESI-MS characterization. For the transition metal complexes composed of Fe(II) or Ru(II) or Rh(III) and TPY derivatives, the octahedral TPY?metal?TPY core can be included in the cavity of CB[10]. Three binding modes (1:1, 1:2 and 1:3) have been detected for the binding of the metal?MPTY complexes with CB[10] by ESI-MS. 相似文献
999.
Two coordination polymers, {[Cd(L1)2(L2)] · 0.25H2O} n (I) and {[Cd(L1)(L3)H2O] · 2H2O} n (II) (L1 = 2-pyrimidineamidoxime, L2 = 4-sulfobenzoate dianion and L3 = 5-sulfosalicylate dianion), has been synthesized and structurally characterized by single-crystal X-ray diffraction (CIF files CCDC nos. 1565646 (I) and 1565728 (II)). Complex I crystallizes in monoclinic space group P21/n with a = 10.1462(3), b = 16.0152(5), c = 14.0349(5) Å, β = 93.267(3)°, V = 2276.87(13) Å3, C68H66N32O29S4Cd4, M = 2373.36, ρcalcd = 1.731 g/cm3, μ(MoKα) = 1.109 mm?1, F(000) = 1186, GOOF = 0.806, Z = 1, the final R1 = 0.0287 and wR2 = 0.0733 for I > 2σ(I). Complex II crystallizes in monoclinic space group P21 with a = 6.882(2), b = 17.138(2), c = 7.883(2) Å, β = 103.83(3)°, V = 902.8(4) Å3, C12H16N4O10SCd, M = 520.75, ρcalcd = 1.916 g/cm3, μ(MoKα) = 1.388 mm?1, F(000) = 520, GOOF = 1.047, Z = 2, the final R1 = 0.0739 and wR2 = 0.2041 for I > 2σ(I). Crystal structural analysis reveals that complex I possesses the corrugated 1D chain structure extending along the \([\bar 101]\) direction. However, complex II displays a 2D coordination network lying on the ab crystal plane, which can be simplified as a binodal 3-connected 63 topological network by considering Cd2+ ions and L3 ligands as 3-connected nodes. Their photoluminescent and thermal properties were also investigated. 相似文献
1000.
Yazhou Wang Lixin Wang Zhipeng Ma Lijun Gao Xucai Yin Ailing Song Xiujuan Qin Guangjie Shao Weimin Gao 《Journal of Solid State Electrochemistry》2018,22(10):2977-2987
MnO has a high theoretical capacity, moderate discharge plateau, and low polarization when it is used as the anode material in lithium battery. However, the issues that limit its application are its poor conductivity and large volume changes, which can easily result in the collapse of electrode structure during long-term cycling. In the present work, a carbon-coated MnO/graphene 3D-network anode material is synthesized by an electrostatic adsorption of dispersed precipitates precipitation method. The MnO nanoparticles coated by carbon are uniformly distributed on the surface of graphene nanosheets and form a 3D sandwich-like nanostructure. A carbon layer is coated on the surface of MnO nanoparticles, which slows down the volume expansion in the process of lithium intercalation. The graphene nanosheets are cross-linked through carbons in this 3D nanostructure, which provides mechanical support and effective electron conduction pathways during the charge-discharge. The electrochemical tests indicate that the prepared 3D carbon-coated MnO/graphene electrode exhibits an excellent rate capacity of 1247.3 and 713.2 mAh g?1 at 100 and 1000 mA g?1, respectively. The capacity is 792.2 mAh g?1 after long cycle at a current density of 1000 mA g?1. The specific capacity is higher than that of MnO-based composite lithium anode materials currently reported. The superior rate and cycling performances are attributed to the unique 3D-network structure, which provides an effectively conductive network, buffers volume expansion, and prevents falling and aggregation of MnO in the charge and discharge process of the electrode materials. The 3D-structured carbon-coated MnO/graphene anode material will have an excellent application prospect. 相似文献