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61.
The gyrator is a lossless two-port network which transforms one-port networks into its dual with respect to its gyration conductance. For example, capacitance at the gyrator output is viewed as inductance at the input and a voltage source is transformed to a current source. 相似文献
62.
Significance of urban and agricultural land use for biocide and pesticide dynamics in surface waters 总被引:1,自引:0,他引:1
Biocides and pesticides are designed to control the occurrence of unwanted organisms. From their point of application, these substances can be mobilized and transported to surface waters posing a threat to the aquatic environment. Historically, agricultural pesticides have received substantially more attention than biocidal compounds from urban use, despite being used in similar quantities.This study aims at improving our understanding of the influence of mixed urban and agricultural land use on the overall concentration dynamics of biocides and pesticides during rain events throughout the year. A comprehensive field study was conducted in a catchment within the Swiss plateau (25 km2). Four surface water sampling sites represented varying combinations of urban and agricultural sources. Additionally, the urban drainage system was studied by sampling the only wastewater treatment plant (WWTP) in the catchment, a combined sewer overflow (CSO), and a storm sewer (SS). High temporal resolution sampling was carried out during rain events from March to November 2007.The results, based on more than 600 samples analyzed for 23 substances, revealed distinct and complex concentration patterns for different compounds and sources. Five types of concentration patterns can be distinguished: a) compounds that showed elevated background concentrations throughout the year (e.g. diazinon >50 ng L−1), indicating a constant household source; b) compounds that showed elevated concentrations driven by rain events throughout the year (e.g. diuron 100-300 ng L−1), indicating a constant urban outdoor source such as facades; c) compounds with seasonal peak concentrations driven by rain events from urban and agricultural areas (e.g. mecoprop 1600 ng L−1 and atrazine 2500 ng L−1 respectively); d) compounds that showed unpredictably sharp peaks (e.g. atrazine 10,000 ng L−1, diazinon 2500 ng L−1), which were most probably due to improper handling or even disposal of products; and finally, e) compounds that were used in high amounts but were not detected in surface waters (e.g. isothiazolinones).It can be safely concluded that in catchments of mixed land use, the contributions of biocide and pesticide inputs into surface waters from urban areas are at least as important as those from agricultural areas. 相似文献
63.
Miles AM Singer PC Ashley DL Lynberg MC Mendola P Langlois PH Nuckols JR 《Environmental science & technology》2002,36(8):1692-1698
Trihalomethane (THM) concentrations in blood and tap water were measured for 50 women living in two locations with different bromide concentrations and disinfectant types. Blood samples were taken from each woman early in the morning prior to any major water-use activity and again immediately after showering. Each residence was sampled for THMs in tap water prior to the woman's shower. Cobb County, GA, tap water exhibited high THM concentrations composed primarily of chloroform. Corpus Christi, TX, tap water exhibited lower THM concentrations with significant proportions of brominated THMs. THMs in tap water and blood were compared using mole fraction speciation, extent of bromine incorporation, and correlation analysis. Results indicated that THMs in the blood rose significantly as a result of showering, that showering shifted the THM distribution in the blood toward that found in the corresponding tap water, and that THMs measured in the blood of women living in the two locations reflected species and concentration differences in their respective tap waters. In general, blood concentrations were not significantly correlated with tap water concentrations. This finding suggests that other factors, in addition to tap water concentrations, may be important in determining THM concentrations in the blood. 相似文献
64.
Henrik P. Porte Dmitry Turchinovich Saydulla Persheyev Yongchang Fan Mervyn J. Rose Peter Uhd Jepsen 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(7):883-886
Black silicon is produced by laser annealing of a-Si:H films. During annealing, silicon microstructures are formed on the
surface. We use time-resolved terahertz spectroscopy to study the photoconductivity dynamics in black silicon. We find that
when a copper film is deposited on top of the a-Si:H layer prior to laser annealing, the carrier lifetime of black silicon
is significantly reduced. 相似文献
65.
66.
The endurance of ion-beam-assist-deposited (IBAD) MoS2 is correlated with coating structure and orientation. Structure and orientation are determined by X-ray diffraction, while endurance is measured with a ball-on-disk tribometer operating in dry air. The IBAD MoS2 coatings contain both crystalline and non-crystalline components. Only two orientations of the crystalline component are observed: the (001) planes parallel (basal orientation) and perpendicular (edge orientation) to the surface. Endurance of the coating is not related to coating thickness or substrate chemistry, but is related to the relative amount of the two MoS2 crystal orientations. Coating endurance decreases with increasing edge (100) intensity. Furthermore, MoS2 coatings with poor crystallinity exhibit good endurance. These results are discussed in terms of a possible oxidative wear mechanism and stress-induced basal re-orientation of the non-crystalline IBAD MoS2. 相似文献
67.
Hazel Morton Nancie Gunson Diarmid Marshall Fergus McInnes Andrea Ayres Mervyn Jack 《Computer Speech and Language》2011,25(2):341-362
This paper describes a comprehensive usability evaluation of an automated telephone banking system which employs text-to-speech (TTS) synthesis in offering additional detail on customers’ account transactions. The paper describes a series of four experiments in which TTS was employed to offer an extra level of detail to recent transactions listings within an established banking service which otherwise uses recorded speech from a professional recording artist. Results from the experiments show that participants welcome the added value of TTS in being able to provide additional detail on their account transactions, but that TTS should be used minimally in the service. 相似文献
68.
We sketch the universal critical properties of a quantum superconductor to insulator transition in two spatial dimensions, using the scaling theory of quantum critical phenomena. Comparison with experimental data reveals that the resulting universal relations among transition temperature, zero temperature penetration depth, and residual resistivity, as well as for the asymptotic linear temperature dependence of the penetration depth, appear to apply in a rather extended doping regime, ranging from the underdoped limit up to the nearly optimum dopant concentration. This behavior uncovers the dominant role of quantum fluctuations in this doping regime. 相似文献
69.
Singer A.C. Oppenheim A.V. Wornell G.W. 《Signal Processing, IEEE Transactions on》1999,47(10):2768-2782
Solitons are eigenfunction solutions to certain nonlinear wave equations that arise in a variety of natural and man-made systems. Their rich properties and tractability make them an intriguing component of such systems, often describing the large-scale or long-term behavior of natural systems, or the information content in certain communication or signal processing systems. However, it is often difficult to detect or estimate the parameters of solitons in such systems due to the presence of strong nonsoliton components or the nonlinear interaction of multiple solitons. The objective of this paper is to develop and investigate the detection and estimation of soliton signals. As a framework for this study, we consider using these nonlinear systems as both signal generators and signal processors in a form of multiplexed soliton communication. In contrast to more conventional uses of solitons in a communications context, our communication system uses soliton systems for signal generation and multiplexing for transmission over traditional linear channels. In addition to their mathematical tractability and the simplicity of the analog circuits used to generate and process them, we show that the soliton signal dynamics may also provide a mechanism for decreasing transmitted signal energy while enhancing signal detection and parameter estimation performance 相似文献
70.