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141.
Chromatography using polyamide column is one of the most critical purification operations that affect the safety and efficacy of traditional Chinese medicine (TCM) products. To ensure successful operation and reduce time and solvent consumption, UV spectroscopy combined with multivariate data analysis as an online analytical tool was developed for monitoring the polyamide column chromatography of the TCM Danshen. The process trajectories were established by principal component analysis of the UV spectra and used to determine the endpoint of the washing stage and investigate the impacts of the process conditions. The online analysis method developed determined the concentration of salvianolic acid B (an important compound in Danshen) in the effluent rapidly and precisely with a coefficient of determination of 0.9963 and helped to collect salvianolic acid B quantitatively for determining the endpoint of elution. The methodology proposed is an effective approach applicable in guiding successful operations in the chromatographic separation. 相似文献
142.
Haibin Huang Qinhui Chen Junhui He Longhui Zheng Baoling Chen Jinhuo Lin 《Colloid and polymer science》2014,292(12):3085-3093
Janus materials with anisotropic chemical structures and physical properties have attracted increasing attention due to their diversified potential applications. In this paper, titanium dioxide/3-(trimethoxysilyl) propylmethacrylate (TiO2/MPS) was obtained by swelling assisted with extrusion of PS@TiO2. Then, the phenolic resin (PF) was coated on the surface of MPS lobe. Finally, TiO2/C Janus composite particles were obtained by sintering at the atmosphere of nitrogen. The middle objects during reactive process and the final product were systematically characterized. Results showed that the Janus porous particles of TiO2/C were snowman-like structure, in which the average diameter of the carbon lobe was 178 nm and that of TiO2 lobe was 226 nm. When used as photocatalysts for Rhodamine B degradation in aqueous solution under UV irradiation, the resulted Janus product exhibited more efficient photocatalytic activity than TiO2 hollow microspheres. Graphical abstract
Schematic illustration of swelling polymerization approach to synthesize TiO2/C Janus composite particles and its photocatalytic activity for the degradation of rhodamine B 相似文献
143.
Hui ZhaoWuyou Fu Haibin YangYang Xu Wenyan ZhaoYanyan Zhang Hui ChenQiang Jing Xuefeng QiJing Cao Xiaoming ZhouYixing Li 《Applied Surface Science》2011,257(21):8778-8783
TiO2/Fe2O3 core-shell nanocomposition film has been fabricated via two-step method. TiO2 nanorod arrays are synthesized by a facile hydrothermal method, and followed by Fe2O3 nanoparticles deposited on TiO2 nanorod arrays through an ordinary chemical bath deposition. The phase structures, morphologies, particle size, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and ultraviolet-visible (UV-vis) spectrophotometer. The results confirm that Fe2O3 nanoparticles of mean size ca. 10 nm coated on the surface of TiO2 NRs. After depositing Fe2O3, UV-vis absorption property is induces the shift to the visible-light range, the annealing temperature of 600 °C is the best condition for UV-vis absorption property of TiO2/Fe2O3 nanocomposite film, and increasing Fe content, optical activity are enhanced one by one. The photoelectrochemical (PEC) performances of the as-prepared composite nanorods are determined by measuring the photo-generated currents under illumination of UV-vis light. The TiO2 NRs modified by Fe2O3 show the photocurrent value of 1.36 mA/cm2 at 0 V vs Ag/AgCl, which is higher than those of unmodified TiO2 NRs. 相似文献
144.
145.
Ning Chen Sijian Gao Jichuan Huo Haibin Wang Jichuan He Yongchang Zhu 《Journal of Thermal Analysis and Calorimetry》2014,116(2):875-879
High-temperature thermal transformation of aluminum–chromium phosphates has been investigated by means of DSC–TG, IR, and XRD analysis. The relative dielectric constant and thermal decomposition were measured and discussed. The results show that crystallization and thermal decomposition started at about 1,273 K, only AlPO4 and Cr2O3 have been found at 1,873 K due to the decomposition of PO 3 ? , P2O 7 2? , and PO 4 3? . The relative dielectric constant is fluctuant. 相似文献
146.
Highly Efficient Chemical Process To Convert Mucic Acid into Adipic Acid and DFT Studies of the Mechanism of the Rhenium‐Catalyzed Deoxydehydration
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Dr. Xiukai Li Di Wu Dr. Ting Lu Dr. Guangshun Yi Prof. Haibin Su Dr. Yugen Zhang 《Angewandte Chemie (International ed. in English)》2014,53(16):4200-4204
The production of bulk chemicals and fuels from renewable bio‐based feedstocks is of significant importance for the sustainability of human society. Adipic acid, as one of the most‐demanded drop‐in chemicals from a bioresource, is used primarily for the large‐volume production of nylon‐6,6 polyamide. It is highly desirable to develop sustainable and environmentally friendly processes for the production of adipic acid from renewable feedstocks. However, currently there is no suitable bio‐adipic acid synthesis process. Demonstrated herein is the highly efficient synthetic protocol for the conversion of mucic acid into adipic acid through the oxorhenium‐complex‐catalyzed deoxydehydration (DODH) reaction and subsequent Pt/C‐catalyzed transfer hydrogenation. Quantitative yields (99 %) were achieved for the conversion of mucic acid into muconic acid and adipic acid either in separate sequences or in a one‐step process. 相似文献
147.
Design of Thermally Stable Amine–Imine Nickel Catalyst Precursors for Living Polymerization of Ethylene: Effect of Ligand Substituents on Catalytic Behavior and Polymer Properties
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Dr. Haibin Hu Lei Zhang Dr. Haiyang Gao Prof. Fangming Zhu Prof. Qing Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3225-3233
Nickel complexes bearing amine–imine ligands with various backbone substituents were synthesized and employed as ethylene polymerization catalysts on activation with Et2AlCl. The substituent on the backbone carbon atom of the amine moiety is decisive for the living nature of ethylene polymerization. A bulky amine–imine nickel precursor with a tert‐butyl group on the carbon atom of the amine group can polymerize ethylene in a living fashion at an elevated temperature of 65 °C, which is the highest temperature of living polymerization of ethylene with late transition‐metal catalysts. The wide applicable temperature range for living polymerization and sensitivity of the branch structure of the polyethylene to temperature enable precise synthesis of di‐ and triblock polyethylenes featuring different branched segments by sequential tuning of the polymerization temperature. 相似文献
148.
Fe2O3/Al2O3 and Fe2O3/Al2O3 modified by low content of Ni (below 2% in weight) oxygen carriers were prepared by mechanical mixing and impregnation method. The synthesized oxygen carriers were characterized by means of X‐ray diffraction (XRD), X‐ray fluorescence (XRF), scanning electron microscopy (SEM), BET‐surface area and temperature programmed reduction (TPR). Besides, redox cyclic reactivity and the performance of chemical looping reforming of methane of the oxygen carriers were studied in a thermal gravimetrical analysis (TGA) and fixed bed at 850°C. It was observed that the redox reactivity of the oxygen carriers is improved by Ni addition because synergic effect may occur between NiO and Fe2O3/Al2O3 to form NiFe2O4 and NiAl2O4 spinel phases. However, the improvement was not apparent as Ni addition reached 1 wt% or more because more nickel loaded resulted in methane decomposition into H2 and carbon leading to carbon deposition. The SEM and BET analysis showed that NiFe2O4 and NiAl2O4 particles dispersed into the pores of the Fe2O3/Al2O3 particles in the course of preparation. In addition, the resistance to sintering of the modified samples increased with the Ni addition increasing. The results of successive redox cycles showed that the Ni modified Fe2O3/Al2O3 oxygen carriers have good regenerability. With integration of reactivity and carbon deposition, the content 1.04 wt% of nickel doping was an optimal amount in the three modified samples. 相似文献
149.
用智能波长校正的扫描式ICP光谱仪测定铬铁矿中六种元素成分 总被引:2,自引:1,他引:1
本文利用作者所在实研究室开发的扫描式ICP光谱仪的智能波长校正装置取代传统的ICP光谱仪的局部恒温系统,测定了铬铁矿及铬酸盐中的Cr,Si,Al,Fe,Mn和Mg六种元素成分。测定结果与铬矿标样的鉴定值基本一致,测量的相对标准偏差(RSD)为1.0%,智能波和工校正装置的波长校正结果与谱线峰值描迹结果的比较表明,该智能波长校正装置是有效的,具有省时,安全,结构简单的特点,有广泛的应用的前景。 相似文献
150.
利用一与射频脉冲同步的门控信号使探头在发射和接收时呈现不同的Q值,从而能够在不降低接收14N NQR信号的情噪比条件下极大地缩小探头的恢复时间.初步的实验结果表明:通过适当选择衰减电阻的阻值,提出的探头设计能够将常规探头的"死时间"限制在20μs以内. 相似文献