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91.
Are quantum dots ready for in vivo imaging in human subjects? 总被引:2,自引:0,他引:2
Nanotechnology has the potential to profoundly transform the nature of cancer diagnosis and cancer patient management in the
future. Over the past decade, quantum dots (QDs) have become one of the fastest growing areas of research in nanotechnology.
QDs are fluorescent semiconductor nanoparticles suitable for multiplexed in vitro and in vivo imaging. Numerous studies on
QDs have resulted in major advancements in QD surface modification, coating, biocompatibility, sensitivity, multiplexing,
targeting specificity, as well as important findings regarding toxicity and applicability. For in vitro applications, QDs
can be used in place of traditional organic fluorescent dyes in virtually any system, outperforming organic dyes in the majority
of cases. In vivo targeted tumor imaging with biocompatible QDs has recently become possible in mouse models. With new advances
in QD technology such as bioluminescence resonance energy transfer, synthesis of smaller size non-Cd based QDs, improved surface
coating and conjugation, and multifunctional probes for multimodality imaging, it is likely that human applications of QDs
will soon be possible in a clinical setting. 相似文献
92.
Structure-activity relationship observations for European corn borer moth pheromone and fluoro analogs via computer molecular modeling 总被引:1,自引:0,他引:1
J. D. Warthen J. A. Klun M. Schwarz N. Wakabayashi 《Journal of chemical ecology》1995,21(12):1921-1930
Structure-activity relationship (SAR) observations were made for theZ-type European corn borer moth pheromone, (Z)-11-tetradecen-1-ol acetate, and a series of analogs with fluorination in the alcohol portion of the molecule. The attractiveness of these analogs and the pheromone was compared to the electrostatic potential map of the molecular mechanics (MM) minimized lowest energy conformation for each compound. A critical range of electrostatic potential on the protons of the double-bond appears to be essential for optimal acceptor fit and attractiveness. 相似文献
93.
不同分子量聚酯的羟值分析方法 总被引:11,自引:1,他引:11
用醋酐/高氯酸/乙酸乙酯法,醋酐吡啶回流法,分别对相对分子质量为1100-12000的聚酯进行了羟值的测定,并用气压渗透法和析出物溶解重滴法进行了核对。结果表明醋酐/高氯酸/乙酸乙酯法对于M〈5000的聚酯是适用的,而高分子量的聚酯则必须用醋酐/吡啶回流法,才能获得满意的结果。 相似文献
94.
Solid extraction of caffeine and theophylline from green tea by molecular imprinted polymers 总被引:1,自引:0,他引:1
Dexian?Wang Seung?Pyo?Hong Kyung?Ho?RowEmail author 《Korean Journal of Chemical Engineering》2004,21(4):853-857
This paper involves a feasibility study on using molecular imprinted polymers as the sorbent materials in solid phase extraction
for caffeine and theophylline from green tea. Two kinds of MIPs, with caffeine-theophylline mixture and pentoxifylline-theophylline
mixture as the templates respectively, MAA as the monomer, EDMA as the crosslinker and ATBN as the initiator, were applied
to this purpose. Mixture solution of caffeine and theophylline (1 Μg/ ml in acetonitrile) was applied to the solid extraction
cartridges following a load, wash and elute procedure with acetonitrile, methanol, methanol-acetic acid (90/10, v/v) as the
solvents, respectively. This solid phase extraction protocol was applied for extraction of caffeine and theophylline from
green tea. Comparison between the results obtained with the MIPs cartridges and a traditional C18 reversed-phase cartridge was made. It showed that the MIP-based sorbent on the solid phase extraction was comparable with
that of C18 material. HPLC analysis using a C18 column (5 Μm, 250× 4.6 mm from Rstech corporation), methanol: water (60 :40, v/v) as the mobile phase at a flow rate of 0.6
ml/min was applied for the quantitative determination. 相似文献
95.
The epoxidation of propylene catalyzed by a reaction-controlled phase transfer catalyst [π-C5H5NC16H33]3[PW4O16] is investigated. The H2O2 is generated by the oxidation of 2-ethylanthrahydroquinone (EAHQ) with molecular oxygen in the organic solvent. Under mild conditions, the selectivity for propylene oxide, based on propylene, is 95%, and the yield, based on 2-ethylanthrahydroquinone, is 85%. During the epoxidation, the catalytic system is homogeneous. However, after the H2O2 is used up, the catalyst can be recovered as a precipitate and can be reused. After the epoxidation reaction, 2-ethylanthraquinone can be regenerated to 2-ethylanthrahydroquinone by catalytic hydrogenation, and no coproduct is produced. 相似文献
96.
Samy A. Madbouly 《Polymer》2007,48(14):4097-4107
The miscibility and molecular dynamics of nanostructured maleated polypropylene (mPP)/polycarbonate (PC) blends prepared by in situ polymerization of macrocyclic carbonates with polypropylene modified with 0.5 wt% of maleic anhydride-reactive groups were investigated over a wide range of frequencies (10−2-0.5 × 107 Hz) at different constant temperatures using broadband dielectric spectroscopy and scanning transmission electron microscope (STEM). The molecular dynamics of the glass relaxation process of the blend (α-relaxation process) appeared at a lower temperature range compared with that of the pure PC. This shift in the molecular relaxation process is attributed to the partial miscibility of the two polymer components in the blends as previously confirmed by the morphology via STEM. Nanoscale morphologies with average domain diameters as small as 50 nm were obtained for the different blend compositions studied. The STEM photographs show that the graft mPP-g-PC prefers to locate at the interfaces as previously reported. The relaxation spectrum of pure PC and mPP/PC blends was resolved into α- and β-relaxation processes using the Havriliak-Negami equation and ionic conductivity. The dielectric relaxation parameters, such as relaxation peak broadness, maximum frequency, fmax, and dielectric strength, Δ? (for the α- and β-relaxation processes), were found to be blend composition dependent. The kinetics of the α-relaxation processes of the blends were well described by Vogel-Fulcher-Tammann (VFT) equation. The local process of PC was resolved into two relaxation processes β1 and β2, associated with the carbonyl groups' motion and the combined motions of carbonyl and phenylene groups, respectively. Only β2 shifted to lower frequency in the blend while β1 was relatively not affected by blending. The electric modulus of the blends was used to get a sufficient resolution of the different relaxation processes in the samples, i.e., α-, β-relaxation processes, ionic conductivity, and interfacial polarization. In addition, the blending method used was found to increase the d.c. conductivity without affecting the charge carrier transport mechanism, making it possible to develop novel polymer blends with tunable dielectric properties and morphology from existing polymers. 相似文献
97.
By means of the molecular dynamics (MD) simulation, the crystallization mechanism of 22,8-polyurethane which contains hydrogen-bond units is investigated and the results show that the crystallization process at a fixed temperature can be characterized by three stages: (1) The extended chain collapses to a globular random coil; (2) The random coil reorganizes into an ordered lamellar structure; (3) Accompanied with the segments clustering due to the hydrogen-bond formation, the lamellar develops with local defects. Two kinds of hydrogen-bond, which are formed between NH group and CO group (N-H?OC), and between NH group and urethane alkoxy oxygen (N-H?O), respectively, are found to play an important role in the crystallization process of 22,8-polyurethane. Furthermore, the effect of temperature on the crystallization is also studied by selecting three temperatures 200, 300 and 400 K. The lower the crystal temperature is, the slower the crystallization rate is and the stronger the hydrogen-bonding interactions are presented. This is in harmony with the experimental results. 相似文献
98.
PPTA/尼龙1010分子复合材料流变行为的研究 总被引:2,自引:0,他引:2
本文采用共沉淀法制备了聚对苯二甲酰对苯二胺(PPTA)/尼龙1010分子复合材料。测定了PPTA/尼龙1010分子复合材料的流变行为,发现PPTA使尼龙1010的表观熔体粘度变大,且PPTA/尼龙1010分子复合材料的表观熔体粘度对温度的敏感性不象尼龙1010那样突出。 相似文献
99.
Environmental concerns have stimulated interest in utilizing plant-derived materials in various industrial fields. The main objective of the present study was to synthesize a new type of high-performance lignin series dispersant of coal–water slurry (CWS) from wheat straw alkali lignin (WAL), and determine the affecting factors in the reaction and the application performance for CWS preparation. The experimental results showed that the inherent viscosity and the sulfonic group content of the modified wheat straw alkali lignin (MSL) are the key factors affecting its dispersing effect for CWS. In the reaction, the reactant mass concentration and the sulfonating agent amount were changed to obtain the MSL with different inherent viscosities and sulfonic group contents, and the MSL with intermediate inherent viscosity (6.0 ml/g) and higher sulfonic group content (1.80 mmol g− 1) was found to have excellent dispersing effect for CWS. The MSL obtained from optimized process was used as dispersant for CWS preparation, the studies of the properties of CWS showed that MSL has similar dispersing effect with naphtalenesulfonate–formaldehyde condensate, and far better dispersing effect than lignosulphonate. Recently this kind of new dispersant has been applied in several power plants in China. 相似文献
100.
Molecular sieve properties of activated carbon fibers modified by cracking treatment with methane are studied herein. The effect of methane treatment on the porous texture of the samples has been studied while varying temperature and time. These materials have been evaluated for their selectivity during CO2 and CH4 separation; their uptakes have been compared with non-treated activated carbon fibers (studied previously), which were considered suitable to be used as molecular sieves. Kinetics of CO2 and CH4 uptake have also been investigated in this research. The treatment produced materials exhibiting fast kinetics and high selectivity during CO2 and CH4 separation; at the same time however, the CO2 uptake capacity was diminished. 相似文献