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151.
Microwave Sol–Gel Synthesis of CaGd2(MoO4)4:Er3+/Yb3+ Phosphors and Their Upconversion Photoluminescence Properties 下载免费PDF全文
Chang Sung Lim Victor Atuchin Aleksandr Aleksandrovsky Maxim Molokeev Aleksandr Oreshonkov 《Journal of the American Ceramic Society》2015,98(10):3223-3230
CaGd2(MoO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (x = Er3+ + Yb3+, Er3+ = 0.05, 0.1, 0.2, and Yb3+ = 0.2, 0.45) have been successfully synthesized by the microwave sol–gel method, and the crystal structure refinement and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after heat‐treatment at 900°C for 16 h, showed a well‐crystallized morphology. Under the excitation at 980 nm, CaGd2(MoO4)4:Er3+/Yb3+ particles exhibited strong 525 and 550‐nm emission bands in the green region and a weak 655‐nm emission band in the red region. The Raman spectrum of undoped CaGd2(MoO4)4 revealed about 15 narrow lines. The strongest band observed at 903 cm?1 was assigned to the ν1 symmetric stretching vibration of MoO4 tetrahedrons. The spectra of the samples doped with Er and Yb obtained under 514.5 nm excitation were dominated by Er3+ luminescence preventing the recording Raman spectra of these samples. Concentration quenching of the erbium luminescence at 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions in the CaGd2(MoO4)4:Er3+/Yb3+ crystal structure was established to be approximately at the 10 at.% doping level. 相似文献
152.
Processing of Piezocomposites by Fused Deposition Technique 总被引:1,自引:0,他引:1
Amit Bandyopadhyay Raj K. Panda Victor F. Janas Mukesh K. Agarwala Stephen C. Danforth Ahmad Safari 《Journal of the American Ceramic Society》1997,80(6):1366-1372
Piezoelectric ceramic/polymer composites were made by a fused deposition (FD) technique, which is a solid-freeform fabrication (or layered manufacturing) technique where three-dimensional (3-D) objects are built layer by layer from a computer-aided design (CAD) file on a computer-controlled fixtureless platform. Indirect and direct FD methods were used to fabricate lead zirconate titanate (PZT)/polymer composites. For the indirect method, a CAD file for the negative image of the final part was created. A polymer mold was made via FD using a thermoplastic filament, and composite formation was completed via a lost mold technique. In the direct FD method, a thermoplastic polymeric filament that was filled with 50–55 vol% of PZT powder was used to form a positive image of the desired structure. Three-dimensional honeycomb ("3-D honeycomb") composites and "ladder" composites with 3-3 connectivity, which were formed via the FD technique, showed excellent electromechanical properties for transducer applications. In addition, the FD technique showed the ability to form composites with controlled phase periodicity, various volume fractions, and a variety of microstructures and macrostructures that are not possible with traditional composite-forming techniques. 相似文献
153.
Sol–gel synthesis of Tb‐doped hydroxyapatite with high performance as photocatalyst for 2, 4 dichlorophenoxyacetic acid mineralization 下载免费PDF全文
154.
Influence of ionic liquid composition on the stability of polyvinyl chloride‐based ionic liquid inclusion membranes in aqueous solution 下载免费PDF全文
Francisca Tomás‐Alonso Aurora M. Rubio Alfonso Giménez Antonia P. de los Ríos Maria J. Salar‐García Victor M. Ortiz‐Martínez Francisco J. Hernández‐Fernández 《American Institute of Chemical Engineers》2017,63(2):770-780
Membrane technology has gained significant importance with the incorporation of ionic liquids into their structure. This work shows the influence of ionic liquid composition on the stability of PVC‐based polymer ionic liquid inclusion membranes (PILIMs) in aqueous solution. Among the ILs investigated, those membranes which contain between 20 and 30%w/w of the least soluble, [OMIM+][PF6?] and [OMIM+][Ntf2?], exhibit losses of IL lower than 10%. For both ILs, the amount immobilized was maximum for the membranes with 30%w/w of IL (0.0838 and 0.0832 g, respectively). On the contrary, the ionic liquid loss increases as its solubility in water increase, reaching 99.52% when PILIMs are prepared with 70%w/w of [OMIM+][BF4?]. The results demonstrate that the stability of PILIMs depends on the solubility of the IL in the surrounding phase and the specific interaction between the IL and the polymeric support for PVC‐to‐IL ratios higher than 30%w/w. © 2016 American Institute of Chemical Engineers AIChE J, 63: 770–780, 2017 相似文献
155.
Laccase‐containing ureasil–polymer composite as the sensing layer of an amperometric biosensor 下载免费PDF全文
Taras Kavetskyy Oleh Smutok Mykhailo Gonchar Olha Demkiv Halyna Klepach Yuliia Kukhazh Ondrej Šauša Tamara Petkova Victor Boev Vania Ilcheva Plamen Petkov Andrey L. Stepanov 《应用聚合物科学杂志》2017,134(36)
Innovative amperometric biosensors for monitoring the level of wastewater pollution have been constructed on the surface of the gold planar electrodes C220AT “DropSens” by using the organic–inorganic ureasil‐based composites as host matrixes and immobilized commercial laccase from Trametes versicolor . It was found that the biosensor based on the ureasil–chalcogenide glass composite is characterized by a very high sensitivity (67,540 А M?1 m?2) that is 38.3 times higher than for pure ureasil (the sensitivity of the bioelectrode was calculated as 1762 А M?1 m?2). On the other hand, application of the ureasil–chalcogenide glass composite with incorporated silver nanoparticles (NPs) synthesized by high‐dose (1.0 × 1017 Ag+/cm2) 30 keV Ag+ ion implantation results in decreasing the biosensor sensitivity up to 2390 times (the sensitivity of the bioelectrode was 28.3 А M?1 m?2). The role of additives (chalcogenide glass and silver NPs) in the ureasil matrix on the biofunctionality of the biosensors produced is considered. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45278. 相似文献
156.
Modification of absorbent poly(glycerol‐glutaric acid) films by the addition of monoglycerides 下载免费PDF全文
Prince G. Boakye Kerby C. Jones Nicholas P. Latona Cheng‐Kung Liu Samuel A. Besong Stephen E. Lumor Victor T. Wyatt 《应用聚合物科学杂志》2017,134(40)
Monoglycerides (MGs) have been incorporated into the matrix of poly(glycerol‐co‐glutaric acid) films to investigate their effect on the thermal, mechanical, and solvent absorption properties of the resultant films. Solvent absorption studies revealed that poly(glycerol‐co‐glutaric acid‐co‐MG) films were able to absorb and resorb solvents better than poly(glycerol‐co‐glutaric acid) films, albeit they had higher erosion levels. Thermogravimetric analysis showed that the incorporated MGs did not affect the thermal stability of the glycerol‐based films. The MG‐incorporated films were observed to be much softer than the poly(glycerol‐co‐glycerol) films which was further proven by a 39‐fold reduction in Young's Modulus and 17‐fold reduction in fracture energy when compared to the poly(glycerol‐co‐glycerol). Mechanical property studies also revealed that the incorporation of MGs increased the elongation % and reduced the tensile strength of poly(glycerol‐co‐glutaric acid) films. Correlation analysis revealed a strong linear relationship between Young's Modulus and fracture energy (R2 = 0.9962), and between Young's Modulus and tensile strength (R2 = 0.9972). Our study proved that MGs can be successfully incorporated in the polymer matrix of poly(glycerol‐co‐glutaric acid) films to produce softer films with increased elongation and increased solvent absorption capacity. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45381. 相似文献
157.
Evaluation of Simple and Inexpensive High-Throughput Methods for Phytic Acid Determination 下载免费PDF全文
Victor Raboy Amy Johnson Kristin Bilyeu Henrik Brinch-Pedersen Karen Cichy Richard F. Hurrell Christophe Zeder Søren K. Rasmussen Tom D. Warkentin Pushparajah Thavarajah Jinrui Shi Lan Zhou Qingyao Shu 《Journal of the American Oil Chemists' Society》2017,94(3):353-362
High‐throughput/low‐cost/low‐tech methods for phytic acid determination that are sufficiently accurate and reproducible would be of value in plant genetics, crop breeding and in the food and feed industries. Variants of two candidate methods, those described by Vaintraub and Lapteva (Anal Biochem 175:227–24, 1988 ; “VL” methods) and Huang and Lantzsch (J Sci Food Agric 34:1423–1426, 1983 ; “HL” methods), were evaluated. The primary concern with these methods is that, due to interference of matrix constituents including inorganic P, they can overestimate phytic acid and are ineffective at low levels of phytic acid. Twelve seed flours, representing lines of soybean, maize, barley and dry bean, containing a wide range of phytic acid levels, were analyzed by a minimum of eight cooperating laboratories using three variants of the VL method and two variants of the HL method. No method had consistently acceptable (?2.0”) “Horwitz ratios”, a measure of reproducibility, although some treatments approached that. For example, one variant of the VL method when used to assay a soybean flour with a “standard” level of phytic acid had a Horwitz ratio of 2.15. Some variants of the VL method were adequate for analyses of cereal grains regardless of phytic acid level but none accurately measured phytic acid when at low levels in soybean flours. One variant of the HL method in which the 0.2 N HCl extraction media is modified to contain 10% Na2SO4, did accurately measure phytic acid levels in both cereal and legume flours regardless of endogenous phytic acid levels or matrix constituents. 相似文献
158.
Victor Buhl Møller Kim Dam-Johansen Sarah Maria Frankær Søren Kiil 《Journal of Coatings Technology and Research》2017,14(2):279-306
Industries that work with acidic chemicals in their processes need to make choices on how to properly contain the substances and avoid rapid corrosion of equipment. Certain organic coatings and linings can be used in such environments, either to protect vulnerable construction materials, or, in combination with fiber reinforcement, to replace them. However, degradation mechanisms of organic coatings in acid service are not thoroughly understood and relevant quantitative investigations are scarce. This review describes the uses and limitations of acid-resistant coatings in the chemical industry, with a comparison to alternative resistant materials based on metals or ceramics. In addition, coating degradation phenomena, caused by acid exposure, are mapped to the extent possible, and analysis methods for detecting coating degradation type and severity are listed and discussed. It is concluded that more knowledge on chemical and physical degradation mechanisms is required, and that improvements in resistance to elevated temperatures and abrasion would decrease the risk of use and increase the potential application areas of organic coatings exposed to acidic environments in the chemical industry. 相似文献
159.
160.
AbstractOptimality properties of decision procedures are studied for the quickest detection of a change-point of parameters in autoregressive and other Markov type sequences. The limit of the normalized conditional log-likelihood ratios is shown to exist for Markov chains satisfying the ergodic theorem of information theory. Then closed-form expressions for this limit are derived by making use of the time average rate of Kullback-Leibler divergence. The good properties of the detection procedures based on a sequential analysis approach are proven to hold thanks to geometric ergodicity properties of the observation processes. In particular, the window-limited CUSUM rule is shown to be optimal for detecting the disruption point in autoregressive models. Sparre Andersen models are specifically studied. 相似文献