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81.
Andrew A. Sobek Vijay Rastogi Donald A. Benedetti 《Mine Water and the Environment》1990,9(1-4):133-148
In pyritic environments, the bacteriaThiobacillus ferrooxidans catalyze acid formation by increasing the oxidation rate of pyrite by a factor of one million. This acid solubilizes metals and pollutes adjacent streams and lands. Bactericide sprays during mining and waste disposal operations attack the source of the problem by preventing acid formation and metals solubilization. Used in conjunction with current water treatment systems, bactericides can dramatically reduce operating costs. Controlled release bactericides contribute to successful reclamation by providing assurance against revegetation failure and post-reclamation water quality problems that can necessitate perpetual water treatment. While inhibitingT. ferrooxidans these organic compounds aid in the establishment of beneficial heterotrophic bacteria which support vegetation. These conditions continue to persist after the bactericide is depleted from the controlled release system. Case Studies I and II show that bactericides inhibit acid generation during hard rock and coal mining operations and they are cost effective. Case Studies III and IV illustrate the improvement in water quality and vegetation after reclamation when controlled release bactericides were used. Economic analyses show cost benefits are achieved when controlled-release bactericides are part of the reclamation plan. 相似文献
82.
Ian A. Brummel Daniel E. Drury Andrew R. Kitahara Farid El Gabaly Jon F. Ihlefeld 《Journal of the American Ceramic Society》2021,104(2):711-721
Lithium zirconium phosphate (LiZr2P3O12) thin films have been prepared on platinized silicon substrates via a chemical solution deposition approach with processing temperatures between 700°C and 775°C. Films that were subject to a single high-temperature anneal were found to crystallize at temperatures above 725°C. Crystallization was observed in films annealed after each deposited layer at 700°C and above. In both cases, grain size was found to increase with annealing temperature. Ion conductivity was found to increase with annealing temperature in singly annealed films. In per-layer annealed films ion conductivity was found to initially increase then decrease with increasing annealing temperature. A maximum ion conductivity of 1.6 × 10−6 S/cm was observed for the singly annealed 775°C condition, while a maximum ion conductivity of 5.8 × 10−7 S/cm was observed for the 725°C per-layer annealed condition. These results are consistent with an increasing influence of cross-plane, internal interface resistance and vapor phase carrier loss in the per-layer annealed samples. This work demonstrates that post-deposition processing methods can strongly affect the ion conducting properties of LiZr2P3O12 thin films. 相似文献
83.
A study of 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 shows that, when it is doped with 2.5% Sm on the A-site, in addition to an almost threefold increase in piezoelectric charge coefficient and dielectric permittivity, there is a 2 order of magnitude reduction in conductivity, attributed to a decrease in oxygen vacancy concentration. An analysis of the nonlinearity of permittivity with respect to field amplitude shows that both the reversible and irreversible contributions increase significantly with Sm-doping, with simple models showing that these changes are consistent with a reduction in the concentration of dipolar defects that can inhibit both polarization rotation and domain wall translation. Contrary to the argument that doping increases heterogeneity, there is little change in the diffuseness of the peak in permittivity as a function temperature, whilst there is a 15% increase in spontaneous polarization with Sm addition. Through comparison of the Rayleigh law parameters with those published for other piezoelectric materials, it is concluded that a significant contribution to the observed increase in piezoelectric performance due to Sm-doping of PMN-PT is similar in origin to that seen in soft, donor-doped PZT and other conventional piezoelectric ceramics. 相似文献
84.
Andrew J. Steveson Waltraud M. Kriven 《Journal of the American Ceramic Society》2021,104(7):3397-3410
The K[AlSi2O6]-Cs[AlSi2O6] pseudo-binary system was synthesized by geopolymer crystallization. The thermal expansion properties of these materials were studied by in situ high-temperature X-ray diffraction to characterize thermal expansion behavior for potential application as environmental barrier coatings. Tailorable thermal expansion through changing cation stoichiometry allowed reduced thermal expansion mismatch with SiCf/SiC composites compared to rare-earth-based coatings. 相似文献
85.
Mollie B. Schear Arianna Neal Jadah S. Clarke Andrew P. Saab Carl B. Giller Riccardo Casalini Matthew Laskoski 《应用聚合物科学杂志》2021,138(12):50053
The preparation of highly aromatic elastomers from a bisphenol A-based divinyl-terminated resin and polymerization with various aromatic silane containing compounds utilizing a room temperature hydrosilylation reaction is demonstrated. The polymers exhibit high thermal and oxidative stability with 5% weight losses around 430 and 350°C and char yields ranging from 35% to 40%. The thermosets maintained their elastomeric properties with good hardness and mechanical properties as measured by elongation measurements. The toughness of the thermosets was not improved with the inclusion of aromatic moieties but the hardness did appear to increase with the addition of more aromatic groups. 相似文献
86.
The significance of deposition point standoff variations in multiple-layer coaxial laser cladding (coaxial cladding standoff effects) 总被引:3,自引:0,他引:3
Andrew J. Pinkerton Lin Li 《International Journal of Machine Tools and Manufacture》2004,44(6):573-584
Direct laser deposition (DLD) is an additive manufacturing process that builds up a part layer-by-layer by fusing metal powder to a solid substrate. A coaxial laser and powder delivery head is commonly used, and here a critical process variable is the standoff distance between the nozzle and the material deposition point. This contribution investigates the role of this variable and the effect that it has on the final part geometry. The experimental results show that good layer consistency can, in fact, be obtained with no movement of the substrate between layers for more than 20 layers, or 10 mm under tested conditions, and that poorer results are obtained by regular movement of the substrate by a badly chosen constant amount. A theoretical analysis of the situation establishes a method to estimate melt pool size using an analytically calculated temperature near the heat source. Based on this, simple heat and mass flow models are established to allow some of the results to be explained. 相似文献
87.
This paper presents a visual object tracking system which is tolerant to external imaging factors such as illumination, scale, rotation, occlusion and background changes. Specifically, an integration of an online version of total-error-rate minimization based projection network with an observation model of particle filter is proposed to effectively distinguish between the target object and the background. A re-weighting technique is proposed to stabilize the sampling of particle filter for stochastic propagation. For self-adaptation, an automatic updating scheme and extraction of training samples are proposed to adjust to system changes online. Our qualitative and quantitative experiments on 16 public video sequences show convincing performances in terms of tracking accuracy and computational efficiency over competing state-of-the-art algorithms. 相似文献
88.
模板的安全性和隐私性是掌纹系统实际应用的关键问题,然而生物特征保护的多项指标通常相互冲突并且难以同时满足.作为解决上述冲突的一种可撤销掌纹编码算法,PalmPhasor实现了高效、安全的掌纹认证.建立了系统分析PalmPhasor性能的完整框架.为了便于具体分析,将情景分为4种情况,并且提供了支持相应分析的预备知识,包括辅助定理以及Gabor滤波掌纹图像实部和虚部分布特性.在统计学基础上建立的理论分析和实验结果均表明:即使在用户口令被盗的情况下,多方向分数级融合增强的PalmPhasor算法也可以同时有效地满足可撤销生物特征的4项指标. 相似文献
89.
Richard O. Sinnott Christopher Bayliss Andrew Bromage Gerson Galang Yikai Gong Philip Greenwood Glenn Jayaputera Davis Marques Luca Morandini Ghazal Nogoorani Hossein Pursultani Muhammad Sarwar William Voorsluys Ivo Widjaja 《Journal of Grid Computing》2016,14(4):603-618
Big data technologies and a range of Government open data initiatives provide the basis for discovering new insights into cities; how they are planned, how they managed and the day-to-day challenges they face in health, transport and changing population profiles. The Australian Urban Research Infrastructure Network (AURIN – www.aurin.org.au) project is one example of such a big data initiative that is currently running across Australia. AURIN provides a single gateway providing online (live) programmatic access to over 2000 data sets from over 70 major and typically definitive data-driven organizations across federal and State government, across industry and across academia. However whilst open (public) data is useful to bring data-driven intelligence to cities, more often than not, it is the data that is not-publicly accessible that is essential to understand city challenges and needs. Such sensitive (unit-level) data has unique requirements on access and usage to meet the privacy and confidentiality demands of the associated organizations. In this paper we highlight a novel geo-privacy supporting solution implemented as part of the AURIN project that provides seamless and secure access to individual (unit-level) data from the Department of Health in Victoria. We illustrate this solution across a range of typical city challenges in localized contexts around Melbourne. We show how unit level data can be combined with other data in a privacy-protecting manner. Unlike other secure data access and usage solutions that have been developed/deployed, the AURIN solution allows any researcher to access and use the data in a manner that meets all of the associated privacy and confidentiality concerns, without obliging them to obtain ethical approval or any other hurdles that are normally put in place on access to and use of sensitive data. This provides a paradigm shift in secure access to sensitive data with geospatial content. 相似文献
90.
Andrew Winslow 《Natural computing》2016,15(1):143-151
We introduce a new property of tile self-assembly systems that we call size-separability. A system is size-separable if every terminal assembly is a constant factor larger than any intermediate assembly. Size-separability is motivated by the practical problem of filtering completed assemblies from a variety of incomplete “garbage” assemblies using gel electrophoresis or other mass-based filtering techniques. Here we prove that any system without cooperative bonding assembling a unique mismatch-free terminal assembly can be used to construct a size-separable system uniquely assembling the same shape. The proof achieves optimal scale factor, temperature, and tile types (within a factor of 2) for the size-separable system. 相似文献