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931.
The Assembly‐Disassembly‐Organization‐Reassembly Mechanism for 3D‐2D‐3D Transformation of Germanosilicate IWW Zeolite
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Pavla Chlubná‐Eliášová Yuyang Tian Dr. Ana B. Pinar Dr. Martin Kubů Prof. Jiří Čejka Prof. Russell E. Morris 《Angewandte Chemie (International ed. in English)》2014,53(27):7048-7052
Hydrolysis of germanosilicate zeolites with the IWW structure shows two different outcomes depending on the composition of the starting materials. Ge‐rich IWW (Si/Ge=3.1) is disassembled into a layered material (IPC‐5P), which can be reassembled into an almost pure silica IWW on treatment with diethoxydimethylsilane. Ge‐poor IWW (Si/Ge=6.4) is not completely disassembled on hydrolysis, but retains some 3D connectivity. This structure can be reassembled into IWW by incorporation of Al to fill the defects left when the Ge is removed. 相似文献
932.
Highly Enantioselective Kinetic Resolution of Axially Chiral BINAM Derivatives Catalyzed by a Brønsted Acid
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Dr. Dao‐Juan Cheng Liang Yan Prof. Dr. Shi‐Kai Tian Ming‐Yue Wu Lu‐Xin Wang Zi‐Li Fan Dr. Sheng‐Cai Zheng Prof. Dr. Xin‐Yuan Liu Prof. Dr. Bin Tan 《Angewandte Chemie (International ed. in English)》2014,53(14):3684-3687
A highly efficient strategy for the kinetic resolution of axially chiral BINAM derivatives involving a chiral Brønsted acid‐catalyzed imine formation and transfer hydrogenation cascade process was developed. The kinetic resolution provides a convenient route to chiral BINAM derivatives in high yields with excellent enantioselectivities. 相似文献
933.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of NH Imines and Alkynes by CH/NH Activation
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Ruoyu He Prof. Dr. Zhi‐Tang Huang Prof. Dr. Qi‐Yu Zheng Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2014,53(19):4950-4953
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N? H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C? H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C? H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献
934.
Catalytic Ethanolysis of Kraft Lignin into High‐Value Small‐Molecular Chemicals over a Nanostructured α‐Molybdenum Carbide Catalyst
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Rui Ma Wenyue Hao Xiaolei Ma Ye Tian Prof. Yongdan Li 《Angewandte Chemie (International ed. in English)》2014,53(28):7310-7315
We report the complete ethanolysis of Kraft lignin over an α‐MoC1?x/AC catalyst in pure ethanol at 280 °C to give high‐value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C6–C10 esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg?1. C6 alcohols and C8 esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched‐chain linkage C3H6O in lignin. Hydrogen was found to have a negative effect on the formation of the low‐molecular‐weight products. 相似文献
935.
A Cost‐Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity: FeP Nanowire Array as the Active Phase
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Dr. Ping Jiang Qian Liu Yanhui Liang Dr. Jingqi Tian Prof. Abdullah M. Asiri Prof. Xuping Sun 《Angewandte Chemie (International ed. in English)》2014,53(47):12855-12859
Iron is the cheapest and one of the most abundant transition metals. Natural [FeFe]‐hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale‐up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its β‐FeOOH NA/Ti precursor through a low‐temperature phosphidation reaction. When applied as self‐supported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127 mV to afford current densities of 10 and 100 mA cm2, respectively. The excellent electrocatalytic performance is promising for applications as non‐noble‐metal HER catalyst with a high performance–price ratio in electrochemical water splitting for large‐scale hydrogen fuel production. 相似文献
936.
Efficient Solar Cells Sensitized by Porphyrins with an Extended Conjugation Framework and a Carbazole Donor: From Molecular Design to Cosensitization
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Yueqiang Wang Bin Chen Dr. Wenjun Wu Dr. Xin Li Prof. Dr. Weihong Zhu Prof. Dr. He Tian Prof. Dr. Yongshu Xie 《Angewandte Chemie (International ed. in English)》2014,53(40):10779-10783
Porphyrin dyes containing the carbazole electron donor have been designed and optimized by wrapping the porphyrin framework, introducing an additional ethynylene bridge to extend the wavelength range of light absorption, and further suppression of the dye aggregation by introducing additional alkoxy chains. Application of a cosensitization approach results in improved current density (Jsc) and open‐circuit voltage (Voc) values, thus achieving the highest cell efficiency of 10.45 %. This work provides an effective combined strategy of molecular design and cosensitization for developing efficient dye‐sensitized solar cells (DSSCs). In addition, carbazole has been demonstrated to be a promising donor for porphyrin sensitizers. 相似文献
937.
LAl H2(L=(Z)-4-[(2,6-二异丙基苯基)氨基]戊-3-烯-2-亚基-2,6-二异丙基苯胺)分别与2-噻吩苯硼酸和2-苯并噻吩硼酸反应,合成含铝氧硼六元环的化合物LAl[OB(2-thiophen)]2(μ-O)(2)和LAl[OB(2-benzo[b]thiophen)]2(μ-O)(3)。LAl H2与2,6-二甲基苯硼酸反应生成了LAl[OB(2,6-CH3C6H4)OH]2(4)。化合物4是化合物2和3的中间体。所有化合物都进行了IR、1H NMR和元素分析等表征。并通过X射线单晶衍射测定了化合物2和4的单晶结构。 相似文献
938.
The infrared(IR) spectra of the N-methylacetamide molecule in water are calculated by using the MD simulation with high-level QM/MM corrections. The B3LYP and MP2 levels with 6-311++G** basis set are used for the QM region, respectively. Our results show all IR spectra at the B3LYP level are well consistent with the corresponding MP2 results. A dynamical charge fluctuation is observed for each atom along the simulation trajectories due to the electrostatic polarization(EP) effects from surrounding solvent environment. We find that the QM/MM corrected IR spectra satisfactorily reproduce the experimental vibrational features of amide I–III modes. 相似文献
939.
A simple, cheap and non-enzymatic colorimetric strategy for glucose detection has been designed based on the interactions between a phenylboronic acid (PBA) derivative, which is coupled with gold nanoparticles (AuNPs) as the colorimetric reporters, and glucose. The PBA-AuNPs hybrid system proposed here exhibits ordered photochemistry behaviors upon the addition of glucose at different pH values. There are two linear regions of glucose concentration for the glucose sensor at different pH values, i.e., between 0.1 mmol/L and 9.8 mmol/L at pH 6 with the detection limit of 64μmol/L and between 0 and 6.5 mmol/L with the detection limit of 48 μmol/L at pH 9, respectively. To test the practicality of the sensor system, we also applied this assay to detect a glucose sample in the artificial saliva. 相似文献
940.
In this paper, a novel magnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186–312, and the limit of detection(S/N = 3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples. 相似文献