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991.
992.
Jian Zhang Bin Wang Ming Li Min-Jian Zhao Jian-Rong Li 《Journal of Coordination Chemistry》2016,69(14):2193-2199
Through ligand modification, we have replaced the central benzene ring of H2TDBA ([1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid) with the pyridine structurally related ligand H2PDDA (4,4′-(pyridine-2,6-diyl)dibenzoic acid), which makes the central pyridine ring of H2PDDA more coplanar with two benzene rings on both sides of the ligand. The modification results in a dramatically different linkage configuration, thereby allowing structural changes to the metal-organic frameworks (MOFs). Two 2-D MOFs, [Cu(TDBA)(DMA)2]·H2O (BUT-221, DMA = N,N-dimethylacetamide), and [Cu3(PDDA)3(DMA)2(H2O)]·5H2O (BUT-223) have been synthesized through reactions of two ditopic carboxylate ligands with Cu(NO3)2·3H2O under solvothermal conditions, and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. Topological analysis shows that BUT-221 is a twofold parallel interpenetrating 44 2-D network with a skl topology, while BUT-223 is a 2-D network with a kgm topology. 相似文献
993.
A new carboline alkaloid, 1-(7-methoxy-quinolinyl-4′-yl)-3,4-dihydro-β-carboline (1), was isolated from the leaves and twigs of Trigonostemon lii Y.T. Chang, together with three known ones, trigonostemonines C and D (2 and 3), and trigonoliimine A (4). Their structures were elucidated by spectroscopic analyses, including 2D-NMR techniques. 相似文献
994.
Xue Xie Jianming Zhou Lin Sun Hongda Zhang Yiwu Zhao Yaling Song 《Natural product research》2016,30(2):150-156
One new flavonol glycoside, 6-hydroxykaempferol-3-O-β-D-glucoside-7-O-β-D-glucuronide (1), together with eight known flavonoids and three known quinochalcones, was isolated from the florets of Carthamus tinctorius L. Their structures were determined by extensive spectroscopic analyses. Their cardioprotective effects against H2O2-induced apoptosis in H9c2 cells were also evaluated; compounds 1, 2, 4–5, 7–10 and 12 provided significant protective effects on H2O2-induced H9c2 cells at the concentration of 25 μg/mL. 相似文献
995.
Lin-Feng Dai Qian Liang Tie Liu Ming-Yu He Ping Zhao 《Natural product research》2016,30(14):1639-1645
One new tigliane-type diterpene, 4-deoxy-4(β)H-8-hydroperoxyphorbol-12-benzoate-13-isobutyrate (1), together with two known diterpenoids, 3-acetyl-5,8-dibenzoyl-14α-propanoyl-13,17-epoxy-7-myrsinaone diterpene with C9–C10 cyclised to form an additional lactone ring (2), Euphodendriane A (3) have been isolated from the whole plants of Euphorbia dracunculoides Lam. Their structures were elucidated by means of extensive spectroscopic analysis (NMR and HR-ESI-MS) and comparison with data reported in the literature. This is the first isolation of 8-hydroperoxy tigliane diterpene (1) from the genus of Euphorbia. All compounds were evaluated for their antifungal activities. 相似文献
996.
Ting Zhao Katarzyna Kurpiewska Justyna Kalinowska‐Tłuścik Eberhardt Herdtweck Prof. Dr. Alexander Dömling 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):3009-3018
The synthesis of all 20 common natural proteinogenic and 4 otherα‐amino acid‐isosteric α‐amino tetrazoles has been accomplished, whereby the carboxyl group is replaced by the isosteric 5‐tetrazolyl group. The short process involves the use of the key Ugi tetrazole reaction followed by deprotection chemistries. The tetrazole group is bioisosteric to the carboxylic acid and is widely used in medicinal chemistry and drug design. Surprisingly, several of the common α‐amino acid‐isosteric α‐amino tetrazoles are unknown up to now. Therefore a rapid synthetic access to this compound class and non‐natural derivatives is of high interest to advance the field. 相似文献
997.
Increasing the CO2/N2 Selectivity with a Higher Surface Density of Pyridinic Lewis Basic Sites in Porous Carbon Derived from a Pyridyl‐Ligand‐Based Metal–Organic Framework 下载免费PDF全文
Dr. Liangjun Li Ying Wang Dr. Xin Gu Dr. Qipeng Yang Prof. Xuebo Zhao 《化学:亚洲杂志》2016,11(13):1913-1920
The development of functional porous carbon with high CO2/N2 selectivity is of great importance for CO2 capture. In this paper, a type of porous carbon with doped pyridinic sites (termed MOFC) was prepared from the carbonization of a pyridyl‐ligand based MOF. Four MOFCs derived from different carbonizing temperatures were prepared. Structural studies revealed high contents of pyridinic‐N groups and nearly the same pore‐size distributions for these MOFCs. Gas‐sorption studies revealed outstanding CO2 uptake at low pressures and room temperature. Owing to the high content of pyridinic‐N groups, the CO2/N2 selectivity on these MOFCs exhibits values of about 40–50, which are among the top values in carbon materials. Further correlation studies demonstrated that the CO2/N2 selectivities show a positive linear relationship with the surface density of pyridinic‐N groups, thus validating the synergistic effect of the doped pyridinic‐N groups on CO2 adsorption selectivity. 相似文献
998.
Zongyang Qiu Prof. Li Song Prof. Jin Zhao Prof. Zhenyu Li Prof. Jinlong Yang 《Angewandte Chemie (International ed. in English)》2016,55(34):9918-9921
Metal‐nanoparticle‐catalyzed cutting is a promising way to produce graphene nanostructures with smooth and well‐aligned edges. Using a multiscale simulation approach, we unambiguously identified a “Pac‐Man” cutting mechanism, characterized by the metal nanoparticle “biting off” edge carbon atoms through a synergetic effect of multiple metal atoms. By comparing the reaction rates at different types of edge sites, we found that etching of an entire edge carbon row could be triggered by a single zigzag‐site etching event, which explains the puzzling linear dependence of the overall carbon‐atom etching rate on the nanoparticle surface area observed experimentally. With incorporation of the nanoparticle size effect, the mechanisms revealed herein open a new avenue to improve controllability in graphene cutting. 相似文献
999.
Determination and removal of sulfonamides and quinolones from environmental water samples using magnetic adsorbents 下载免费PDF全文
Hao Wu Yating Shi Xiaozhen Guo Shuangli Zhao Juanli Du Hongping Jia Lina He Liming Du 《Journal of separation science》2016,39(22):4398-4407
In this study, the magnetic materials known as polymerized ionic liquid@3‐(trimethoxysilyl)propyl methacrylate@Fe3O4 nanoparticles were synthesized and utilized as potential adsorbents. First, these nanoparticles were applied to the analysis of sulfonamides and quinolones present in different water samples using magnetic solid phase extraction and high‐performance liquid chromatography. Under optimized conditions, the developed method showed excellent detection sensitivity, with limits of detection (S/N = 3) and quantification limits (S/N = 10) within 0.2–1.0 and 0.8–3.4 μg/L, respectively. The spiked recoveries of the SAs and QNs in environmental water samples ranged from 83.5 to 103.0%, with RSDs of less than 4.5%. In addition, the adsorbents effectively removed sulfamethoxazole and ofloxacin present in existing aquatic environments. The adsorption kinetics and isotherms of sulfamethoxazole and ofloxacin on the magnetic adsorbents were studied to assess removal performance. The results indicate that the adsorption process follows a pseudo‐second‐order mechanism, which reveals that the sorption mechanism is the rate‐limiting step and produces high qmax values (sulfamethoxazole = 70.35 mg/g and ofloxacin = 48.95 mg/g), thus demonstrating the enormous adsorption capacity of these magnetic adsorbents. 相似文献
1000.
Phase behavior and Li+ Ion conductivity of styrene‐ethylene oxide multiblock copolymer electrolytes 下载免费PDF全文
Solid polymer electrolytes are attractive materials for use as battery separators. Here, a molecular weight series of polystyrene–polyethylene oxide (PEO) multiblock copolymers was synthesized by the thiol–norbornene click reaction. The subsequent materials were characterized both neat and with a lithium bis‐(trifluoromethane)sulfonimide salt loading [(Li)/(EO)] of 0.1. In general, neat samples demonstrated crystallinity scaling with PEO content. Lithium ion‐containing samples had broad scattering peaks, half of which displayed disordered scattering, even at the lowest block molecular weights (polystyrene = 1 kg/mol, PEO = 1 kg/mol). Fitting of disordered scattering data, using the random phase approximation, yielded χRPA and Rg values that were compared with recent predictive work by Balsara and coworkers. The predictions were accurate near the volume fraction fPEO = 0.5 but deviated symmetrically with volume fraction asymmetry. Samples were also analyzed by electrochemical impedance spectroscopy for their potential to conduct lithium ions. Samples with fPEO ≥ 0.5 demonstrated robust conductivity, whereas samples below this volume fraction conducted very poorly, with one exception (fPEO = 0.24). This work expanded upon our recently reported approach to multiblock copolymer synthesis, demonstrating the improved access of materials to further our fundamental understanding of multiblock copolymers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献