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71.
Dutta P Tipple CA Lavrik NV Datskos PG Hofstetter H Hofstetter O Sepaniak MJ 《Analytical chemistry》2003,75(10):2342-2348
The use of microfabricated cantilevers as bioaffinity sensors was investigated. Since many bioaffinity interactions involve proteins as receptors, we conducted studies of the magnitude, kinetics, and reversibility of surface stresses caused when common proteins interact with microcantilevers (MCs) with nanostructured (roughened) gold surfaces on one side. Exposure of nanostructured, unfunctionalized MCs to the proteins immunoglobulin G and bovine serum albumin (BSA) resulted in reversible large tensile stresses, whereas MCs with smooth gold surfaces on one side produced reversible responses that were considerably smaller and compressive. The response magnitude for nanostructured MCs exposed to BSA is shown to be concentration dependent, and linear calibration over the range of 1-200 mg/L is demonstrated. Stable, reusable protein bioaffinity phases based on unique enantioselective antibodies are created by covalently linking monoclonal antibodies to nanostructured MC surfaces. The direct (label-free) stereoselective detection of trace amounts of an important class of chiral analytes, the alpha-amino acids, was achieved based on immunomechanical responses involving nanoscale bending of the cantilever. The temporal response of the cantilever (delta deflection/delta time) is linearly proportional to the analyte concentration and allows the quantitative determination of enantiomeric purity up to an enantiomeric excess of 99.8%. To our knowledge, this is the first demonstration of chiral discrimination using highly scalable microelectromechanical systems. 相似文献
72.
Application of electrokinetic forces to drive the mobile phase diminishes analyte dispersion in open-channel liquid chromatographic columns due to minimization of shear in the flow field. However, the retentive layer coating the inner walls of such devices slows down the average convective velocity of solute molecules in its vicinity, inherently causing dispersion of analyte bands. In this article, we explore the possibility of reducing such dispersion in electrochromatographic columns by imposing a pressure-driven back flow in the system. Analysis shows that although such a strategy introduces shear in the flow field, the overall dispersion in the mobile phase is reduced. This occurs as the streamline velocity in such a system is greater near the channel walls than that in the center of the conduit, thereby allowing fluid dispersion to counteract wall retention effects. For an optimally chosen magnitude of the back flow, hydrodynamic dispersion of any target species in the mobile phase may be shown to diminish by a factor of 3 and 10/3 in a circular tube and a parallel-plate geometry, respectively. A similar reduction in slug dispersion is also realized in rectangular conduits for all aspect ratios. In trapezoidal geometries with large wedge angles or isotropically etched profiles, this reduction factor may attain values of 10 or greater. 相似文献
73.
Biprodas Dutta Jugdersuren Battogtokh David Mckewon Igor Vidensky Neilanjan Dutta Ian L. Pegg 《Journal of Electronic Materials》2007,36(7):746-752
NaCo2O4 has one of the highest figures of merit among all ceramic thermoelectric materials. Because of its large thermopower and
low resistivity, the ceramic oxide NaCo2O4 is a promising candidate for potential thermoelectric applications. NaCo2O4 is, moreover, a ceramic compound with high decomposition temperature and chemical stability in air and it does not contain
any toxic elements. Like all 3-d transition ions, Co ions have multiple spin and oxidation states. In this investigation,
thermopower and electrical conductivity of NaCo2O4 as a function of substitution of Co by Fe ions were measured. Fe substitution for Co causes resistivity to increase, whereas
the Seebeck coefficient remained nearly invariant, especially above 330 K.
An erratum to this article can be found at 相似文献
74.
Tao Zhang Eric van den Berg Sunil Madhani Ashutosh Dutta Shantidev Mohanti 《Wireless Networks》2007,13(5):617-633
Mobile users and devices want to discover and share a growing range of information as the processing and storage capabilities
of mobile devices grow. For example, users want to discover nearby networks, and location-based or time-sensitive user information
contents. A mobile device may want to discover neighboring networks and the parameters required to access these networks so
that it can intelligently decide which networks to use next, and use its existing network connection to authenticate with
selected neighboring networks before it moves into the coverage areas of the selected networks. This can significantly reduce
handoff delays. Existing service discovery frameworks are not effective for such neighboring network discovery or for discovering
dynamic, location- or time-sensitive user information contents. This paper describes and evaluates a new approach—Mobile Information
Services enabled by Mobile Publishing (MIS-MP)—for real time collection, discovery, and sharing of network and user information.
With MIS-MP, mobiles take full advantage of the wealth of information they can accumulate during their routine mobility and
use of networks to help each other to discover the information they want when and where they want it. This is accomplished
by mobiles publishing the information they collect about the networks they visited, and the user information contents they
learned or used, to make the information available to other mobiles. This paper presents analytical models and simulation
results to evaluate the feasibility and performance of MIS-MP. It also describes a testbed implementation of MIS-MP and some
of the lessons we learned.
Tao Zhang is Director of Mobile Networking Research Group at Telcordia Technologies, Piscataway, New Jersey, USA. He develops and directs
research and advanced development programs in mobile networking and applications, including mobility and applications across
heterogeneous radio networks, mobile information services, vehicular networking, mobile peer-to-peer applications, sensor
networking and applications, and collaborative networking .Dr. Zhang’s work has led to several new commercial products. He
co-authored the book “IP-Based Next Generation Wireless Networks” published by John Wiley & Sons in 2004. He initiated the International Conference on Collaborative Computing: Networking,
Applications, and Worksharing (CollaborateCom), and has been serving in various roles for it. Dr. Zhang holds 4 U.S. patents,
with over 25 more pending. He received the 2000 Telcordia CEO Award (for most exceptional teams and individuals who have achieved
a significant business success) and 2002 SAIC’s Executive Science and Technology Council Publication Prize.
Eric van den Berg received his Ph.D. in Applied Mathematics from Cornell University in 1999. After obtaining his degree, he joined Telcordia
Technologies, where he is a Research Scientist in Applied Research Department. His research interests include traffic modeling
and performance analysis of IP- and wireless networks. He received the 2000 Telcordia CEO Award (for most exceptional individuals
and teams who have achieved a significant business success) and the 2002 SAIC Executive Science and Technology Council Publication
Prize.
Sunil Madhani is a Distinguished MTS with Motorola where he manages the IP Realization team in Mobile Device Technology Office. He aims
at working on unconventional and disruptive IP technologies. His current research focus is on convergent networks, dynamic
mobility management and fast handoff in secured/seamless wireless LAN/WAN roaming. His past research includes registration/configuration
protocols in wireless environment, application layer mobility management, secured Mobile IP, managed DOS attack sensor and
TCP/IP boosters. Sunil Madhani holds MS (2002) in Engineering Management & System from Columbia University and MS (1997) in
Computer Science from State University of New York. 相似文献
75.
S. C. Dutta Roy D. K. Bhargava 《International Journal of Circuit Theory and Applications》1977,5(3):235-238
For any realization of a network function F(s) = N(s)/D(s), the sensitivities that can be most readily calculated are those of the coefficients in N(s) and D(s). A simple relationship is derived that enables one to calculate the root (pole and zero) sensitivities of F(s) in terms of the coefficient sensitivities. The root sensitivities, in turn, enable one to calculate the root pair Q and root frequency sensitivities, which can be used to characterize and compare different realizations of F(s). Application to 3rd- and 4th-order filters reveals formulations that are more elegant than those already known in the literature. 相似文献
76.
Amit Kumar Dubey Praveen Gupta Subashisa Dutta Bimlesh Kumar 《International journal of remote sensing》2013,34(23):7815-7827
In this study, river stage variation derived from satellite altimetry was used to assess the water level, monthly discharge, and annual water yield at six virtual gauging stations at the braided reaches of the Brahmaputra River. The braided reaches of the river dynamically change their planform, thalweg line, and aggradation or degradation period. Stage records derived from the Envisat satellite of the European Space Agency and Topex/Poseidon of NASA/CNES were used for the period 2002–2010. Spatial interpolation and datum correction were applied on altimetry-derived river stage records before analysis. A correlation and error analysis between the in situ and satellite-altimetry-derived stages was carried out for these stations for both monsoon and non-monsoon seasons. Yearly optical satellite images were used for qualitative assessment of temporal variations in aggradation/degradation phases at the gauging stations. Using the pseudo-rating curve, discharges at two virtual gauging stations were estimated. The results show that the altimetry-estimated discharges are of good agreement with observed discharge for the monsoon months (June–September) as compared with the non-monsoon months (October–May). In order to assess the annual water yield variability, yearly variation in annual water yield from the altimetry data was also estimated and compared to that observed. The estimated annual water yields were 90% accurate. Similarly, the long-term averaged monthly discharge series estimated from satellite altimetry closely follows the temporal trend of that of the observed series. 相似文献
77.
The structure, morphology, and properties of an ionomer, poly(ethylene‐acrylic‐acid) neutralized by zinc salts (PI) depend on the free carboxylic acid content. In this work, metal acetates (Na, Zn, and Al acetates) were used to control the neutralization levels. A wide range of techniques were used, such as spectroscopic Fourier transform infrared spectroscopy (FTIR), thermal [thermogravimetric analysis, modulated differential scanning calorimetry (MDSC), and dynamic mechanical analysis (DMA)], mechanical (tensile measurement), and small angle neutron scattering (SANS). The melt rheological properties of the samples were also examined. The results show that metal acetate neutralizes free acrylic acid in the ionomer, which has the primary role in controlling ionic association. The number of ionic groups in ionic domains and multiplets in the matrix is dependent on the neutralization level. Metal valence determines the ionic domain or multiplet structure (FTIR), further properties of PI. Dynamic mechanical properties, the ionic transition behaviour, and the mechanical properties are improved compared with PI using monovalent cation (Na+), but decreased using trivalent cation (Al3+) or shows less significant changes due to steric effects. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
78.
Cd1 ? x Pb x S thin films were prepared by spray pyrolysis technique onto glass substrate at 300°C temperatures. The prepared films were characterized elemental, structural and optical properties by energy dispersive X-ray, scanning electron microscopy, X-ray diffraction and UV-VIS spectrophotometer. Energy dispersive X-ray confirmed the presence of Cd, S and Pb in the films. SEM images show that the deposition covered the substrate well uniformly and incorporation of Pb. Crystal structure was found hexagonal and the estimated grain size was lies in between 9 to 49 nm. The optical band gap was decreased from 2.43 to 2.07 eV. 相似文献
79.
Saikat Maitra Farooq Ahmad Ananta K. Das Santanu Das Binay K. Dutta 《Bulletin of Materials Science》2010,33(2):185-190
In the present work the reaction between fly ash and lime in fly ash-lime compacts under water curing and steam curing conditions
was studied thoroughly in relation to the processing conditions. Fly ash from different sources were collected, characterized,
mixed with lime in different ratios and compacted. The compacts were cured with water and steam separately. The reduction
in the free CaO content in these compacts was measured as a function of curing time and curing process. Role of two ionic
additives, FeCl3 and MgCl2, on the reaction between fly ash and lime was also investigated by measuring the free CaO content. Kinetics of these reactions
was studied by determining the reaction order and rate constants with respect to the free CaO content and it was observed
that the curing conditions and additives affected the reaction kinetics significantly. 相似文献
80.