全文获取类型
收费全文 | 590篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 172篇 |
金属工艺 | 50篇 |
机械仪表 | 3篇 |
建筑科学 | 10篇 |
矿业工程 | 1篇 |
能源动力 | 10篇 |
轻工业 | 19篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 88篇 |
一般工业技术 | 151篇 |
冶金工业 | 17篇 |
自动化技术 | 79篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 40篇 |
2021年 | 40篇 |
2020年 | 34篇 |
2019年 | 17篇 |
2018年 | 29篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 23篇 |
2014年 | 19篇 |
2013年 | 23篇 |
2012年 | 41篇 |
2011年 | 39篇 |
2010年 | 32篇 |
2009年 | 25篇 |
2008年 | 21篇 |
2007年 | 32篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 9篇 |
2002年 | 12篇 |
2001年 | 4篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有624条查询结果,搜索用时 15 毫秒
161.
Boyanov MI Fletcher KE Kwon MJ Rui X O'Loughlin EJ Löffler FE Kemner KM 《Environmental science & technology》2011,45(19):8336-8344
Reduction of U(VI) to U(IV) as the result of direct or indirect microbial activity is currently being explored for in situ remediation of subsurface U plumes, under the assumption that U(IV) solubility is controlled by the low-solubility mineral uraninite (U(IV)-dioxide). However, recent characterizations of U in sediments from biostimulated field sites, as well as laboratory U(VI) bioreduction studies, report on the formation of U(IV) species that lack the U═O(2)═U coordination of uraninite, suggesting that phases other than uraninite may be controlling U(IV) solubility in environments with complexing surfaces and ligands. To determine the controls on the formation of such nonuraninite U(IV) species, the current work studied the reduction of carbonate-complexed U(VI) by (1) five Gram-positive Desulfitobacterium strains, (2) the Gram-negative bacteria Anaeromyxobacter dehalogenans 2CP-C and Shewanella putrefaciens CN32, and (3) chemically reduced 9,10-anthrahydroquinone-2,6-disulfonate (AH(2)QDS, a soluble reductant). Further, the effects of 0.3 mM dissolved phosphate on U(IV) species formation were explored. Extended X-ray absorption fine structure (EXAFS) spectroscopy analysis demonstrated that the addition of phosphate causes the formation of a nonuraninite, phosphate-complexed U(IV) species, independent of the biological or abiotic mode of U(VI) reduction. In phosphate-free medium, U(VI) reduction by Desulfitobacterium spp. and by AH(2)QDS resulted in nonuraninite, carbonate-complexed U(IV) species, whereas reduction by Anaeromyxobacter or Shewanella yielded nanoparticulate uraninite. These findings suggest that the Gram-positive Desulfitobacterium strains and the Gram-negative Anaeromyxobacter and Shewanella species use distinct mechanisms to reduce U(VI). 相似文献
162.
Mishra B O'Loughlin EJ Boyanov MI Kemner KM 《Environmental science & technology》2011,45(22):9597-9603
Magnetite and green rust have been shown to reduce aqueous Hg(II) to Hg(0). In this study, we tested the ability of magnetite and green rust to reduce Hg(II) sorbed to 2 g · L(-1) of biomass (Bacillus subtilis), at high (50 μM) and low (5 μM) Hg loadings and at pH 6.5 and 5.0. At high Hg:biomass loading, where Hg(II) binding to biomass is predominantly through carboxyl functional groups, Hg L(III)-edge X-ray absorption spectroscopy showed reduction of Hg(II) to Hg(0) by magnetite. Reduction occurred within 2 h and 2 d at pH 6.5 and 5.0, respectively. At low Hg:biomass loading, where Hg(II) binds to biomass via sulfhydryl functional groups, Hg(II) was not reduced by magnetite at pH 6.5 or 5.0 after 2 months of reaction. Green rust, which is generally a stronger reductant than magnetite, reduced about 20% of the total Hg(II) bound to biomass via sulfhydryl groups to Hg(0) in 2 d. These results suggest that Hg(II) binding to carboxyl groups does not significantly inhibit the reduction of Hg(II) by magnetite. However, the binding of Hg(II) to biomass via sulfhydryl groups severely inhibits the ability of mixed Fe(II/III) phases like magnetite and green rust to reduce Hg(II) to Hg(0). The mobility of heavy metal contaminants in aquatic and terrestrial environments is greatly influenced by their speciation, especially their oxidation state. In the case of Hg, reduction of Hg(II) to Hg(0) can increase Hg mobility because of the volatility of Hg(0). Since Hg is typically present in aquatic and terrestrial systems at low concentrations, binding of Hg(II) to high-affinity sites on bacteria could have important implications for the potential reduction of Hg(II) to Hg(0) and the overall mobility of Hg in biostimulated subsurface environments. 相似文献
163.
164.
Nikolay S. Struchkov Evgeny V. Alexandrov Alexey V. Romashkin Gennady O. Silakov Maxim K. Rabchinskii 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(3):214-220
AbstractA spray-coating technique for deposition of thin uniform graphene oxide films with a thickness of several tens of nanometers was developed. Among distinctive features of the technique is the low substrate heating temperature, which allows preserving most oxygen-containing functional groups and coat a wide range of substrates. The morphology of the spray-coated graphene oxide films with flakes of different lateral sizes was investigated. The local laser-induced photo-thermal reduction of thin graphene oxide thin films was demonstrated. The sensitivity of reduced graphene oxide to water vapor was also measured. Spray-coating and laser reduction techniques can be further applied for humidity sensor fabrication. 相似文献
165.
Characterization of cross‐linking depth for thin polymeric films using atomic force microscopy 下载免费PDF全文
Qiuquan Guo Maxim Paliy Brad Kobe Tomas Trebicky Natalie Suhan Gilles Arsenault Lorenzo Ferrari Jun Yang 《应用聚合物科学杂志》2015,132(8)
Thin polymeric films made with various elastomers, like polyisoprene, and elastomer composites were prepared for characterization of cross‐linking depth in this study. Various cross‐linking methods have been applied to get mechanically stronger, more thermally stable and chemically resistant polymer coatings. However, there is no existing approach that could effectively characterize the degree or depth of cross‐linking for thin polymer films. The objective of this work is to use atomic force microscopy to characterize cross‐linking depth in a precise way. Hyperthermal hydrogen bombardment‐induced cross‐linking was employed as a cross‐linking method and the depth of cross‐linking was estimated via local change of the elastic modulus along the sample cross‐section with precise force measurement and high spatial resolution. It is found that the cross‐linking depth is closely related to the chemical composition of thin films. Understanding the depth of cross‐linking is vital for a broad range of applications. It is believed that the developed technique is also applicable for studying other cross‐linkable materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41493. 相似文献
166.
Jochen Rick Oliver Speck Simon Maier Oliver Tüscher Olaf Dössel Jürgen Hennig Maxim Zaitsev 《Magma (New York, N.Y.)》2010,23(3):165-176
Object
Most functional magnetic resonance imaging (fMRI) experiments use gradient-echo echo planar imaging (GE EPI) to detect the blood oxygenation level-dependent (BOLD) effect. This technique may fail in the presence of anatomy-related susceptibility-induced field gradients in the human head. In this work, we present a novel 3D compensation method in combination with a template-based correction that can be optimized over particular regions of interest to recover susceptibility-induced signal loss without acquisition time penalty. 相似文献167.
Yurkin MA Maltsev VP Hoekstra AG 《Journal of the Optical Society of America. A, Optics, image science, and vision》2006,23(10):2578-2591
We perform a rigorous theoretical convergence analysis of the discrete dipole approximation (DDA). We prove that errors in any measured quantity are bounded by a sum of a linear term and a quadratic term in the size of a dipole d when the latter is in the range of DDA applicability. Moreover, the linear term is significantly smaller for cubically than for noncubically shaped scatterers. Therefore, for small d, errors for cubically shaped particles are much smaller than for noncubically shaped ones. The relative importance of the linear term decreases with increasing size; hence convergence of DDA for large enough scatterers is quadratic in the common range of d. Extensive numerical simulations are carried out for a wide range of d. Finally, we discuss a number of new developments in DDA and their consequences for convergence. 相似文献
168.
McCulloch I Bailey C Genevicius K Heeney M Shkunov M Sparrowe D Tierney S Zhang W Baldwin R Kreouzis T Andreasen JW Breiby DW Nielsen MM 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2006,364(1847):2779-2787
Organic electronics technology, in which at least the semiconducting component of the integrated circuit is an organic material, offers the potential for fabrication of electronic products by low-cost printing technologies, such as ink jet, gravure offset lithography and flexography. The products will typically be of lower performance than those using the present state of the art single crystal or polysilicon transistors, but comparable to amorphous silicon. A range of prototypes are under development, including rollable electrophoretic displays, active matrix liquid crystal (LC) displays, flexible organic light emitting diode displays, low frequency radio frequency identification tag and other low performance electronics. Organic semiconductors that offer both electrical performance and stability with respect to storage and operation under ambient conditions are required. This work describes the development of reactive mesogen semiconductors, which form large crosslinked LC domains on polymerization within mesophases. These crosslinked domains offer mechanical stability and are inert to solvent exposure in further processing steps. Reactive mesogens containing conjugated aromatic cores, designed to facilitate charge transport and provide good oxidative stability, were prepared and their liquid crystalline properties evaluated. The organization and alignment of the mesogens, both before and after crosslinking, were probed by grazing incidence wide-angle X-ray scattering of thin films. Both time-of-flight and field effect transistor devices were prepared and their electrical characterization reported. 相似文献
169.
In the present paper we have derived the analytical expressions for the modes of twisted elliptical fibers with torsional mechanical stress at various relationships of the fiber parameters. It was shown that circularly polarized optical vortices with the topological charges ±1 can propagate in elliptical fibers as generic modes if ellipticity and the twist-induced circular birefringence suppress the spin-orbit interaction. A comparison of the obtained results with the corresponding results for spun elliptical fibers is made. 相似文献
170.
Mohammed Ibrahim Shukoor Filipe Natalio Muhammad Nawaz Tahir Matthias Wiens Marco Tarantola Helen Annal Therese Matthias Barz Stefan Weber Maxim Terekhov Heinz C. Schröder Werner E. G. Müller Andreas Janshoff Patrick Theato Rudolf Zentel Laura Maria Schreiber Wolfgang Tremel 《Advanced functional materials》2009,19(23):3717-3725
Here, design of the first pathogen‐mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced into the polymer chain to trace the nanoparticles in Caki‐1 (human kidney cancer) cells. The ssDNA coupled nanoparticles are used to target Toll‐like receptors 9 (TLR9) receptors inside the cells and to activate the classical TLR cascade. The presence of TLR9 is demonstrated independently in the Caki‐1 cell line by western blotting and immunostaining techniques. The magnetic properties of the MnO core make functionalized MnO nanoparticles potential diagnostic agents for magnetic resonance imaging (MRI) thereby enabling multimodal detection by a combination of MR and optical imaging methods. The trimodal nanoparticles allow the imaging of cellular trafficking by different means and simultaneously are an effective drug carrier system. 相似文献