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971.
The purpose of this work was to study the effect of dendrimer modified clay minerals on the structure and properties of ethylene-propylene-diene monomer (EPDM) nanocomposites.Flame-retardant and dendrimer modified organic montmorillonite (FR-DOMt) was successfully prepared by Na+-montmorillonite, tetrahydroxymethyl phosphonium chloride (THPC), N, N-dihydroxyl-3-aminomethyl propionate, and boric acid. This dendritic type of organoclay (OC) was used in preparation of EPDM/FR-DOMt nanocomposites. The properties of these nanocomposites were studied. The dispersion status of the layered silicates in EPDM was revealed by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD and TEM results showed that FR-DOMt was exfoliated in the EPDM matrix when 10 phr of FR-DOMt was incorporated. The mechanical behavior, thermal stability, and flame retardance of the samples were examined. The experimental data demonstrated that the EPDM hybrids owned an improved tensile strength and elongation at break. In addition, the nanocomposites exhibited higher thermal stability and flame retardance than that of unfilled EPDM matrix. 相似文献
972.
973.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(11):1024-1029
The crystal structures of mono‐ and dinuclear CuII trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate)2 and BDPA, a water‐bound CuII mononuclear complex, aqua(benzyldipicolylamine‐κ3N ,N′ ,N ′′)bis(trifluoromethanesulfonato‐κO )copper(II) tetrahydrofuran monosolvate, [Cu(CF3SO3)2(C19H19N3)(H2O)]·C4H8O, (I), and a triflate‐bridged CuII dinuclear complex, bis(μ‐trifluoromethanesulfonato‐κ2O :O ′)bis[(benzyldipicolylamine‐κ3N ,N′ ,N ′′)(trifluoromethanesulfonato‐κO )copper(II)], [Cu2(CF3SO3)4(C19H19N3)2], were synthesized. The presence of residual moisture in the reaction medium afforded water‐bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single‐crystal X‐ray structure analysis reveals that the CuII centres adopt slightly distorted octahedral geometries in both complexes. The metal‐bound water molecule in (I) is involved in intermolecular O—H…O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C—H…F(triflate) and C—H…O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT–IR and UV–Vis spectroscopy, cyclic voltammetry and elemental analysis. 相似文献
974.
通过控制4,4'-二氨基二苯甲烷环氧树脂(TGDDM)和丙烯酸(AA)的摩尔比(1∶2)合成了化学共混的含混杂活性端基的多官能团齐聚物MVEO-2,直接将多官能团环氧树脂TGDDM与多官能团环氧乙烯基树脂MVER通过物理共混得到聚合物共混物MVEOmix.研究了化学共混和物理共混对含混杂活性端基多官能团齐聚物的结构、性能和形态的影响.红外光谱(FTIR)和核磁共振谱(1H NMR)表明,MVEO-2和MVEOmix具有相同的结构组成.凝胶渗透色谱(GPC)分析表明MVEOmix具有双峰结构且分子量分布较窄,而MVEO-2具有多峰结构且分子量分布较宽.热重分析(TGA)和动态热机械分析(DMA)表明,MVEO-2的热稳定性比MVEOmix更高.MVEO-2的强度和韧性比MVEOmix明显提高,弯曲强度提高17%,拉伸强度提高38%,断裂伸长率提高35%,冲击强度提高24%.扫描电镜结果表明化学共混形成了更均匀紧密的互穿聚合物网络结构. 相似文献
975.
Yue-Xia Zhang Zhen-Hua Yang Quan-Xi Zhang Rui-Jin Li Hong Geng Chuan Dong 《中国化学快报》2015,26(1):157-159
The aim of this study was to investigate the chemical compositions of chalk dust and examine the adverse effects of fine chalk particle matters (PM2.5) on rat alveolar macrophages (AMs) in vitro. Morphologies and element concentrations of chalk particles were analyzed using quantitative energydispersive electron probe X-ray microanalysis (ED-EPMA). The oxidative response of AMs exposed to chalk PM2.5 was measured by luminol-dependent chemiluminescence (CL). The results showed that (1) Chalk dust was mainly composed of gypsum (CaSO4), calcite (CaCO3)/dolomite (CaMg(CO3)2), and organic adhesives; (2) Fine chalk particles induced the AM production of CL, which was inhibited by about 90% by diphenyleneiodonium chloride (DPI). Based on these results, we showed that cytotoxicity of chalk PM2.5 may be related to the reactive oxygen species (ROS) generation. 相似文献
976.
Highly optically pure (R)- and (S)-3-ethylmercapto-2-methylpropionic acids were synthesized by using optically active (D)- and (L)-2,10-camphorsultams as chiral auxiliaries, respectively. Their derivatives, (R)- and (S)-EMMPNmB (m=6-12), were prepared for investigation. Microscopic texture observations demonstrated that the materials possess three stable frustrated phases: BP, TGBA* and TGBC* phases. Interestingly, it was found that the N* phase behaves as an intermediary phase between BP and TGBA* phases in a rather narrow temperature range (calc. 0.5-1.4°C). A study of the racemic mixture, (±)-EMMPNmB (m=10), indicated that the chirality of the molecule could suppress the formation of smectic phases in the heating process. An increase of alkyl chain length favoured the formation of the TGB phases particularly, in accompaniment with a change of TGB phases from monotropic to enantiotropic. Moderate maximum P S values (calc. 14-19 nC cm-2) and apparent tilt angle (calc. 20°) were obtained for the TGBC* phase in a surface stabilized ferroelectric liquid crystal geometry. 相似文献
977.
《Journal of carbohydrate chemistry》2013,32(9):827-841
The unique reactive intermediate formed in the 3,4,6‐tri‐O‐benzyl‐d‐glucal–TfOH (triflic acid)–n‐Bu4NI reaction system (in dichloromethane) reacted with nucleophiles in a regio‐ and stereoselective manner. These selectivities resulted in hitherto unknown compounds, such as benzyl 4,6‐di‐O‐benzyl‐2,3‐dideoxy‐3‐iodo‐α‐glucopyranoside, which was obtained in the presence of an iodide ion as a nucleophile. The corresponding 2‐deoxy α‐glycosides were obtained exclusively in the corresponding reaction with hydroxylic nucleophiles. 相似文献
978.
The convenient, scaleable synthesis of a novel ?-fluorinated bisphosphonic acid, incorporating a tethered acrylamide monomer, [1-fluoro-1-phosphono-7-(prop-2-enamido)heptyl]phosphonic acid (1), is described. The α–fluorine substituent offers the advantage (compared to an α–hydroxy) of compatibility with basic conditions in tetraester intermediates (avoiding phosphonate-phosphate rearrangement) while maintaining a phosphonic acidity that mimics that of pyrophosphoric acid. Sodio tetraisopropyl methylenebis(phosphonate) was monoalkylated with 1,6-dibromohexane and fluorinated with Selectfluor. An ω-nitrogen atom was introduced into the tether via incorporation of a phthalimide group, which as a UV-visible chromophore facilitated purification. Subsequent removal of the ester (HCl) and phthalimide (hydrazine) groups yielded ?–F, ω-aminohexyl methylenebis(phosphonic acid), which was reacted with acryloyl chloride at pH 8-9, then treated with HCl to give 1. 相似文献
979.
A coumarin-based reactive probe 1 is reported for the highly selective detection of Cu+. The benzylic ether (C–O) bond of probe 1 can be cleaved selectively by the reaction with Cu+ under a physiological reducing environment, resulting in a fluorescent change. The maximum emission peak exhibited a red shift from 410 nm to 472 nm, and a remarkable enhancement of emission intensity ratios (I472/I410) from 0.26 to 13.82 was observed. 相似文献
980.
In the study, the layered double hydroxide (LDH) of NiZnFe and its composites with date-palm biochar (LDH-DPb) and carbon nanotubes (LDH-cnt) were synthesized for adsorbing reactive black 5 (RB5) dye from aqueous solutions. In the first 5 min, rapid adsorption was followed by a gradual increase in both dye uptake and removal efficiency of up to 60 min of starting time. In the investigated pH range (3.0–8.0), the removal efficiency linearly decreased while the sorption capacity linearly increased for all three adsorbents as their doses increased to 0.3 or 0.4 g following a decreasing trend up to 0.6 g. By increasing the initial RB5 concentration from 10 to 100 mg L−1, the removal efficiency linearly decreased. A nearly perfect fitting of the pseudo-second-order kinetic model to the adsorption data was observed; however, the Elovich kinetic model showed the heterogeneous surface of adsorbents with chemisorption. At the solid–liquid interface, from a thermodynamics point of view, we obtained the nonspontaneous nature of the adsorption of RB5 dye of the studied adsorbents with an increased disorder, which supported the endothermic nature onto the studied adsorption process. Furthermore, a nearly perfect fitting of the Langmuir model was obtained to the adsorption data, thereby suggesting the monolayer adsorption of RB5 dye onto the studied adsorbents. In the Dubinin–Radushkevich model, a good agreement of the calculated adsorption capacities to the experimental values were observed and the chemical adsorption of RB5 dye on to the studied adsorbents was proposed based on E (8 – 16 kJ mol−1). 相似文献