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1.
The heterogeneity nature of networks is the most eminent characteristic in 5G vehicular cognitive radio networks across complex radio environments. Since multiple communicating radios may be in motion at the same time in a vehicle. So, group mobility is the most prominent characteristic that requires to be a deep investigation. Therefore, different communication radios that are moving on a train/bus needed to select the networks simultaneously. Without considering the group mobility feature, there is a possibility that the same network may be selected by each moving node and cause congestion in a particular network. To overcome this problem, a novel network selection technique considering the group mobility feature is proposed to improve the throughput of the network. In this work, a 5G vehicular cognitive radio network scenario is also realized using USRP-2954 and LabVIEW communications system design suite testbed. The performance metrics like transmission delay, packet loss rate, reject rate and, channel utilization for vehicular nodes, are gained to analyze the proposed technique in vehicular cognitive radio networks environment. The proposed technique demonstrates a remarkable improvement in channel utilization for vehicular nodes and outperformed conventional schemes. 相似文献
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Konstantinos A. Lazarou Karilys Gonzlez‐Nieves Indranil Chakraborty Raphael G. Raptis 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7402-7406
The P and M enantiomers of the octanuclear [Fe8(μ4‐O)4(μ‐4‐Cl‐pz)12Cl4] complex, having T symmetry, were resolved by temporary substitution of chloride ligands by racemic 4‐sBu‐phenolates and subsequent crystallization, where the (S)‐ and (R)‐phenolates coordinate selectively to the M and P complexes, respectively. The complexes were characterized by circular dichroism analysis and X‐ray structure determination. This work constitutes a rare example of enantiomeric recognition resulting in spontaneous resolution upon crystallization. 相似文献
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Shilei Zhao Yihui Yuan Qiuhan Yu Biye Niu Jianhe Liao Zhanhu Guo Ning Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15121-15127
By chemical cross‐linking the amidoxime group onto dual‐surfaces of natural ore materials, namely halloysite nanotubes (HNTs), an efficient adsorbent, AO‐HNTs, is developed. AO‐HNTs show high uranium adsorption capacity of 456.24 mg g?1 in 32 ppm uranium‐spiked simulated seawater. In natural seawater, AO‐HNTs reach the high uranium extraction capacity of 9.01 mg g?1 after 30 days’ field test. The dual‐surface amidoximated hollow nanotubular AO‐HNTs exhibit more coordination active sites for uranium adsorption, which is attributed to the high and fast uranium adsorption capacity. Because of the stable natural ore structure, AO‐HNTs also show long service life. Benefiting from the low cost of HNTs, the cost for uranium extraction from seawater is close to the uranium price in the spot uranium market, suggesting that AO‐HNTs could be used for economical extraction of uranium from the oceans. 相似文献
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Bo Huang Hirokazu Kobayashi Tomokazu Yamamoto Takaaki Toriyama Syo Matsumura Yoshihide Nishida Katsutoshi Sato Katsutoshi Nagaoka Masaaki Haneda Wei Xie Yusuke Nanba Michihisa Koyama Fenglong Wang Shogo Kawaguchi Yoshiki Kubota Hiroshi Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2252-2257
Ru is an important catalyst in many types of reactions. Specifically, Ru is well known as the best monometallic catalyst for oxidation of carbon monoxide (CO) and has been practically used in residential fuel cell systems. However, Ru is a minor metal, and the supply risk often causes violent fluctuations in the price of Ru. Performance‐improved and cost‐reduced solid‐solution alloy nanoparticles of the Cu‐Ru system for CO oxidation are now presented. Over the whole composition range, all of the CuxRu1?x nanoparticles exhibit significantly enhanced CO oxidation activities, even at 70 at % of inexpensive Cu, compared to Ru nanoparticles. Only 5 at % replacement of Ru with Cu provided much better CO oxidation activity, and the maximum activity was achieved by 20 at % replacement of Ru by Cu. The origin of the high catalytic performance was found as CO site change by Cu substitution, which was investigated using in situ Fourier transform infrared spectra and theoretical calculations. 相似文献
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Nan Gan Xuan Wang Huili Ma Anqi Lv He Wang Qian Wang Mingxing Gu Suzhi Cai Yanyun Zhang Lishun Fu Meng Zhang Chaomin Dong Wei Yao Huifang Shi Zhongfu An Wei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14278-14283
Provided here is evidence showing that the stacking between triplet chromophores plays a critical role in ultralong organic phosphorescence (UOP) generation within a crystal. By varying the structure of a functional unit, and different on‐off UOP behavior was observed for each structure. Remarkably, 24CPhCz, having the strongest intermolecular interaction between carbazole units exhibited the most impressive UOP with a long lifetime of 1.06 s and a phosphorescence quantum yield of 2.5 %. 34CPhCz showed dual‐emission UOP and thermally activated delayed fluorescence (TADF) with a moderately decreased phosphorescence lifetime of 770 ms, while 35CPhCz only displayed TADF owing to the absence of strong electronic coupling between triplet chromophores. This study provides an explanation for UOP generation in crystal and new guidelines for obtaining UOP materials. 相似文献
7.
Zheng Zhou Xiao‐Ye Wang Zheng Wei Klaus Müllen Marina A. Petrukhina 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15111-15115
Chemical reduction of OBO‐fused double[5]helicene with Group 1 metals (Na and K) has been investigated for the first time. Two doubly‐reduced products have been isolated and structurally characterized by single‐crystal X‐ray diffraction, revealing a solvent‐separated ion triplet (SSIT) with Na+ ions and a contact‐ion pair (CIP) with K+ ion. As the key structural outcome, the X‐ray crystallographic analysis discloses the consequences of adding two electrons to the double helicene core in the SSIT without metal binding and reveals the preferential binding site in the CIP with K+ counterions. In both products, an increase in the twisting of the double helicene core upon charging was observed. The negative charge localization at the central core has been identified by theoretical calculations, which are in full agreement with X‐ray crystallographic and NMR spectroscopic results. Notably, it was confirmed that the two‐electron reduction of OBO‐fused double[5]helicene is reversible. 相似文献
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In this note, we answer a question of JA Thas about partial ‐ designs. We then extend this answer to a result about the embedding of certain partial ‐ designs into Möbius planes. 相似文献