全文获取类型
收费全文 | 915篇 |
免费 | 22篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 29篇 |
综合类 | 1篇 |
化学工业 | 95篇 |
金属工艺 | 25篇 |
机械仪表 | 16篇 |
建筑科学 | 17篇 |
矿业工程 | 4篇 |
能源动力 | 15篇 |
轻工业 | 40篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 115篇 |
一般工业技术 | 56篇 |
冶金工业 | 397篇 |
原子能技术 | 10篇 |
自动化技术 | 117篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 18篇 |
2007年 | 11篇 |
2006年 | 21篇 |
2005年 | 18篇 |
2004年 | 29篇 |
2003年 | 31篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 88篇 |
1997年 | 64篇 |
1996年 | 49篇 |
1995年 | 38篇 |
1994年 | 26篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 34篇 |
1976年 | 53篇 |
1975年 | 3篇 |
1969年 | 4篇 |
1965年 | 2篇 |
排序方式: 共有943条查询结果,搜索用时 15 毫秒
71.
Kathryn M. L. Taylor-Pashow Thomas B. Peters Fernando F. Fondeur Aaron L. Washington II David T. Hobbs 《分离科学与技术》2015,50(18):2853-2865
The Defense Waste Processing Facility (DWPF), responsible for vitrifying high-level waste (HLW) at the Savannah River Site (SRS), is planning to introduce glycolic acid as a reductant during chemical conditioning of the waste prior to vitrification. A portion of this glycolic acid may be recycled back to the tank farm as sodium glycolate. Since glycolate can serve as a complexing agent for a variety of metallic ions, recent studies were performed to examine the effect of glycolate on the removal of Sr and actinides by monosodium titanate (MST) and modified MST (mMST) and the separation of Cs by the caustic-side solvent extraction (CSSX) process. 相似文献
72.
Analysis‐preserving video microscopy compression via correlation and mathematical morphology 下载免费PDF全文
Chong Shao Alfred Zhong Jeremy Cribb Lukas D. Osborne E. Timothy O'Brien III Richard Superfine Ketan Mayer‐Patel Russell M. Taylor II 《Microscopy research and technique》2015,78(12):1055-1061
The large amount video data produced by multi‐channel, high‐resolution microscopy system drives the need for a new high‐performance domain‐specific video compression technique. We describe a novel compression method for video microscopy data. The method is based on Pearson's correlation and mathematical morphology. The method makes use of the point‐spread function (PSF) in the microscopy video acquisition phase. We compare our method to other lossless compression methods and to lossy JPEG, JPEG2000, and H.264 compression for various kinds of video microscopy data including fluorescence video and brightfield video. We find that for certain data sets, the new method compresses much better than lossless compression with no impact on analysis results. It achieved a best compressed size of 0.77% of the original size, 25× smaller than the best lossless technique (which yields 20% for the same video). The compressed size scales with the video's scientific data content. Further testing showed that existing lossy algorithms greatly impacted data analysis at similar compression sizes. Microsc. Res. Tech. 78:1055–1061, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
73.
John M. Davis Ian A. Gravagne Robert J. Marks II 《Circuits, Systems, and Signal Processing》2010,29(6):1141-1165
The convergence of Laplace transforms on time scales is generalized to the bilateral case. The bilateral Laplace transform
of a signal on a time scale subsumes the continuous time bilateral Laplace transform, and the discrete time bilateral z-transform as special cases. As in the unilateral case, the regions of convergence (ROCs) time scale Laplace transforms are
determined by the time scale’s graininess. ROCs for the bilateral Laplace transforms of double sided time scale exponentials
are determined by two modified Hilger circles. The ROC is the intersection of points external to modified Hilger circle determined
by behavior for positive time and the points internal to the second modified Hilger circle determined by negative time. Since
graininess lies between zero and infinity, there can exist conservative ROCs applicable for all time scales. For continuous
time (ℝ) bilateral transforms, the circle radii become infinite and results in the familiar ROC between two lines parallel
to the imaginary z axis. Likewise, on ℤ, the ROC is an annulus. For signals on time scales bounded by double sided exponentials, the ROCs are
at least that of the double sided exponential. The Laplace transform is used to define the box minus shift through which time scale convolution can be defined. Generalizations of familiar properties of signals on ℝ and ℤ include
identification of the identity convolution operator, the derivative theorem, and characterizations of wide sense stationary
stochastic processes for an arbitrary time scales including autocorrelation and power spectral density expressions. 相似文献
74.
S. Dorr Brian Ashley Moerke Michael Bur Chuck Bassett Tony Aderman Dan Traynor Russell D. Singleton Peter H. Butchko Jimmy D. Taylor II 《Journal of Great Lakes research》2010
Diverse management techniques have been used to mitigate conflicts between humans and double-crested cormorants (Phalacrocorax auritus) including harassment methods supplemented by lethal take. In this study we evaluated impacts of programs to harass spring migrating cormorants on the walleye (Sander vitreus) fishery in Brevoort Lake and the yellow perch (Perca flavescens) and walleye fisheries at Drummond Island. Cormorant foraging declined significantly (p < 0.05) at both locations subsequent to initiation of harassment programs. Overall harassment deterred 90% of cormorant foraging attempts while taking less than 6% lethally on average at each site. Yellow perch were a predominate prey item in number and biomass at both locations. Walleye made up a small proportion of the diet at both locations. However, both walleye and yellow perch abundance increased significantly (p < 0.05) at Drummond Island. Walleye abundance at age 3 increased to record levels in 2008 following 3 years of cormorant management at Brevoort Lake. The estimated cormorant consumption of age-1 walleye in the absence of management at Brevoort Lake during 2005 would account for 55% of the record 2006 age-1 walleye population. These results support the hypothesis that cormorant predation on spawning aggregations of sportfish was a significant mortality factor and cormorant management reduced sportfish mortality and increased abundance at both locations. Continuation of harassment programs and fishery assessments will determine whether improvement of targeted sport fisheries through control of spring migrating cormorants is sustainable. 相似文献
75.
Phosphorous Levels in Peeled and Deveined Shrimp Treated with Sodium Tripolyphosphate 总被引:1,自引:0,他引:1
VICKIE TENHET GUNNAR FINNE RANZELL NICKELSON II DON TOLODAY 《Journal of food science》1981,46(2):350-352
Using volumetric and spectrophotometric methods for the determination of phosphorous, untreated shrimp were shown to have high and variable phosphorous content. When peeled and deveined shrimp were treated with 0.5% and 1.0% sodium tripolyphosphate (STP) solutions, the STP uptake was shown to be low. At these low treatment concentrations the phosphorous content in the treated shrimp did not exceed the range of natural phosphorous found in untreated shrimp. When higher treatment concentrations were used, treated thrimp could be identified. The stability of STP in treated shrimp during frozen storage was investigated using a P32 STP isotope. After 2 wk of frozen storage at –26°C only 12% of the total activity could be attributed to STP. At the same time, pyrophosphate was present at a level of 25% and orthophosphate at 27%. During further frozen storage, the STP concentration remained at approxinately 12%, pyrophosphate dropped down to as low as 2% while orthophosphate gradually increased reaching 45% of total activity at the end of 10 wk storage period. 相似文献
76.
Evaluation of intermodel agreement using ISO 13655 M0, M1, and M2 measurement modes in commercial spectrophotometers 下载免费PDF全文
Spectrophotometers are routinely used for color measurement and color management in many commercial printing and proofing workflows. In the case of media containing optical brightening agents, ultraviolet (UV)‐induced fluorescence has led to poor levels of agreement between models from different manufacturers, and different models from the same manufacturer. A relevant standard, ISO 13655, has been revised and now clearly defines measurement modes and conditions for the UV component in spectrophotometers. ISO 13655:2009—Graphic Technology—Spectral Measurement and Colorimetric Computation for Graphic Arts Images now defines four measurement modes: M0, M1, M2, and M3. The intermodel difference between 10 commercially available spectrophotometers is evaluated for different substrate types in measurement modes (M0, M1, and M2) as allowed by each instrument. In particular, the authors compare devices using M0 legacy mode versus newer instruments that are compliant with the new M1 and M2 (UV‐included and UV‐excluded) measurement modes. A finding with significant practical applications is that there is greatly improved intermodel agreement between the new generation of ISO 13655‐compliant instruments in M1 (D50) mode when compared with the previous generation of hand‐held spectrophotometers. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 27–37, 2017 相似文献
77.
Guthold M. Falvo M.R. Matthews W.G. Paulson S. Washburn S. Erie D.A. Superfine R. Brooks F.P. Jr. Taylor R.M. II. 《Mechatronics, IEEE/ASME Transactions on》2000,5(2):189-198
The nanoManipulator system adds a virtual-reality interface to an atomic-force microscope (AFM), thus providing a tool that can be used by scientists to image and manipulate nanometer-sized molecular structures in a controlled manner. As the AFM tip scans the sample, the tip-sample interaction forces are monitored, which, in turn, can yield information about the frictional, mechanical, material, and topological properties of the sample. Computer graphics are used to reconstruct the surface for the user, with color or contours overlaid to indicate additional data sets. Moreover, a force feedback stylus, which is connected to the tip via software, allows the user to directly interact with the macromolecules. This system is being used to investigate carbon nanotubes, DNA, fibrin, adeno- and tobacco mosaic virus. It is now also possible to insert this system into a scanning electron microscope which provides the user with continuous images of the sample, even while the AFM tip is being used for manipulations 相似文献
78.
Boehm Stephen L. II; Schafer Gwen L.; Phillips Tamara J.; Browman Kaitlin E.; Crabbe John C. 《Canadian Metallurgical Quarterly》2000,114(2):401
Neuromuscular impairment by ethanol likely involves complex effects on balance, gait, muscle strength, and other features of motor coordination. The present experiments showed that relative sensitivity to ethanol-induced motor impairment in serotonin 1B (5-HT1B) null mutant and control mice was task dependent. We found that ethanol-treated null mutant mice made fewer missteps on a balance beam than did ethanol-treated wild-type mice, and confirmed a previous finding of their lesser ethanol sensitivity in the grid test. The genotypes did not differ in ethanol sensitivity as measured by the screen test, static dowel, fixed-speed rotarod, accelerating rotarod, grip strength, or loss of righting reflex tests. These experiments suggest that within a behavioral domain, alternative tests of function are not equivalent, so multiple assessment tools should be used to avoid misinterpretation of gene function. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
The Complex Variable Boundary Element Method or CVBEM has recently been applied to the use of new fractal basis functions for defining a global trial function on the problem domain. In that recent advance, a topic for future research was the need for development of an algorithm to construct a global trial function that converges to the true problem boundary conditions, assumed to be continuous on the boundary. In this paper, such an algorithm for constructing a sequence of fractal basis functions is presented. 相似文献
80.
Polyaniline (PAn) dispersed in water was prepared with sodium dodecylsulfonate (SDS) as a surfactant with varying concentrations of aniline and HCl and molar ratios of SDS/aniline. The PAn dispersion was homogeneous and stable, and its pH value could be adjusted. The conductivity of PAn powder, precipitated from this dispersion, was as high as 20 S/cm. The transmission electron microscopy morphology of PAn assembled in the dispersion was particle‐like, fiber‐like, or coil‐like, depending on the initial concentration of SDS and aniline. The polymerization of aniline was accelerated by SDS, which was confirmed by open‐circuit potential measurement during the polymerization process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1550–1555, 2003 相似文献