全文获取类型
收费全文 | 1192篇 |
免费 | 28篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 185篇 |
金属工艺 | 12篇 |
机械仪表 | 19篇 |
建筑科学 | 49篇 |
矿业工程 | 5篇 |
能源动力 | 25篇 |
轻工业 | 87篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
武器工业 | 1篇 |
无线电 | 57篇 |
一般工业技术 | 203篇 |
冶金工业 | 400篇 |
原子能技术 | 6篇 |
自动化技术 | 132篇 |
出版年
2022年 | 4篇 |
2021年 | 26篇 |
2020年 | 13篇 |
2019年 | 20篇 |
2018年 | 22篇 |
2017年 | 9篇 |
2016年 | 20篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 74篇 |
2012年 | 61篇 |
2011年 | 84篇 |
2010年 | 69篇 |
2009年 | 71篇 |
2008年 | 60篇 |
2007年 | 74篇 |
2006年 | 66篇 |
2005年 | 60篇 |
2004年 | 45篇 |
2003年 | 44篇 |
2002年 | 33篇 |
2001年 | 15篇 |
2000年 | 22篇 |
1999年 | 20篇 |
1998年 | 43篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 14篇 |
1992年 | 18篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1969年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有1227条查询结果,搜索用时 109 毫秒
991.
Most polymeric thermoset materials change (cure) slowly as they lie in storage; a prime example of this is composite prepreg materials. These changes are generally vitrification, and are not readily observable using some of the standard cure-monitoring methods, such as DSC and FTIR, which sense mainly the gelation process. Evidence of this observation is presented, along with the successful results of an effort to monitor this shelf-cure process using a simplified resistivity meter. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 337–342, 1997 相似文献
992.
The structural properties of oil-in-water (O/W) emulsions, as well as their oxidative stability upon storage at 50 °C, were studied. Eight different formulations were prepared, with the aim of studying the effect of three variables: the composition of the oil phase, the presence of the flavonoid rutin and the homogenization procedure on the structure and the oxidative stability. It was found that high pressure homogenization, through droplet size reduction, stabilized the emulsions both against creaming and oil oxidation. The interfacial protein was also partially replaced by rutin, further improving the stability of the emulsions, whereas purification of the oil phase had hardly any effect. Thus, the structural and oxidative stability of emulsions was controlled by the size of the droplets and improved by the addition of rutin. 相似文献
993.
Although there is an emerging consensus that social desirability does not meaningfully affect criterion-related validity, several researchers have reaffirmed the argument that social desirability degrades the construct validity of personality measures. Yet, most research demonstrating the adverse consequences of faking for construct validity uses a fake-good instruction set. The consequence of such a manipulation is to exacerbate the effects of response distortion beyond what would be expected under realistic circumstances (e.g., an applicant setting). The research reported in this article was designed to assess these issues by using real-world contexts not influenced by artificial instructions. Results suggest that response distortion has little impact on the construct validity of personality measures used in selection contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
Peng Shang Nadezda A. Stepicheva Haitao Liu Olivia Chowdhury Jonathan Franks Ming Sun Stacey Hose Sayan Ghosh Meysam Yazdankhah Anastasia Strizhakova Donna Beer Stolz J. Samuel Zigler Jr. Debasish Sinha 《International journal of molecular sciences》2021,22(21)
Degeneration of retinal pigment epithelium (RPE) is one of the most critical phenotypic changes of age-related macular degeneration (AMD), the leading cause of vision loss in the elderly. While cultured polarized RPE cells with original properties are valuable in in vitro models to study RPE biology and the consequences of genetic and/or pharmacological manipulations, the procedure to establish mouse primary PRE cell culture or pluripotent stem cell-derived RPE cells is time-consuming and yields a limited number of cells. Thus, establishing a mouse in situ RPE culture system is highly desirable. Here we describe a novel and efficient method for RPE explant culture that allows for obtaining biologically relevant RPE cells in situ. These RPE explants (herein referred to as RPE flatmounts) are viable in culture for at least 7 days, can be efficiently transduced with adenoviral constructs, and/or treated with a variety of drugs/chemicals followed by downstream analysis of the signaling pathways/biological processes of interest, such as assessment of the autophagy flux, inflammatory response, and receptor tyrosine kinases stimulation. This method of RPE explant culture is highly beneficial for pharmacological and mechanistic studies in the field of RPE biology and AMD research. 相似文献
995.
Nabih Youssef Brent Nuttall Owen Hata Onik Tahtakran Gary C. Hart 《The Structural Design of Tall and Special Buildings》2000,9(1):3-24
This paper describes the Los Angeles City Hall building and a unique seismic strengthening program. Four hundred and sixteen high damping rubber bearings, 90 flat sliding bearings and 64 viscous dampers have been installed as part of the seismic rehabilitation. The building is a 460 feet tall steel frame with unreinforced masonry infill. The rehabilitation consists of installing high damping rubber bearings at its base supplemented with nonlinear viscous dampers. This paper describes various aspects of the project including the development of seismic performance goals, identification of inherent seismic deficiencies of the existing building, evaluation of alternative strengthening schemes, the final design process and construction issues. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
996.
Chapman R.A. Holloway T.C. McNeil V.M. Chatterjee A. Stacey G.E. 《Electron Devices, IEEE Transactions on》1997,44(11):1888-1895
The delay time of an inverter or NAND chain at a gate length yielding equal standby current and active current is used as the definition of a maximum Figure of Merit (FOM), FOMmax. The circuit power that occurs under this condition of equal standby and active currents is an equally important measure. This FOMmax technique is particularly useful in characterizing complementary metal-oxide-semiconductor (CMOS) technologies in the deep submicron regime. A knowledge of the exact value of gate length is not necessary to apply the FOMmax methodology. For a fixed supply voltage and gate oxide thickness, node capacitance and transistor drive, and off currents determine the value of FOMmax. The value of gate length at which FOMmax occurs decreases with decreasing supply voltage. FOMmax analysis is applied to the comparison of CMOS technologies using gate oxide thicknesses of 5.7 and 3.8 nm 相似文献
997.
998.
999.
Hualong Du Cameron Lonsdale John Oliver Brent M. Wilson Joseph A. Turner 《Journal of Nondestructive Evaluation》2014,33(1):104-110
In this article, the measurement of quench depth in railroad wheels is demonstrated using a diffuse ultrasonic backscatter technique. A singly-scattered response (SSR) model that accounts for the gradation of lamellar spacing (duplex microstructure) within grains in the direction of ultrasonic propagation is developed based on the previous single-phase model. The effects of a graded microstructure on ultrasonic scattering are observed by comparing the spatial variance curve measured from the tread surface to that measured from the cross section. The experimental results show that the graded SSR model fits the spatial variance curve from the tread surface much better than the uniform SSR model. The spatial variance peaks increase in amplitude and shift to later times when the material path is increased (deeper focus). The experimental variance curve from the tread surface is then fit with the model in a least-squares sense such that the quench depth can be estimated. The diffuse ultrasonic backscatter technique can be used not only to distinguish microstructure changes, but also to quantify the quench depth, an outcome that may be applicable for quality control during manufacturing. 相似文献
1000.
Clara T. H. Tran Alexey Kondyurin Stacey L. Hirsh David R. McKenzie Marcela M. M. Bilek 《Journal of the Royal Society Interface》2012,9(76):2923-2935
The surface of polytetrafluoroethylene (PTFE) was modified using plasma immersion ion implantation (PIII) with the aim of improving its ability to immobilize yeast. The density of immobilized cells on PIII-treated and -untreated PTFE was compared as a function of incubation time over 24 h. Rehydrated yeast cells attached to the PIII-treated PTFE surface more rapidly, with higher density, and greater attachment strength than on the untreated surface. The immobilized yeast cells were removed mechanically or chemically with sodium hydroxide and the residues left on the surfaces were analysed with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). The results revealed that the mechanism of cell attachment on both surfaces differs and a model is presented for each. Rapid attachment on the PIII-treated surface occurs through covalent bonds of cell wall proteins and the radicals on the treated surface. In contrast, on the untreated surface, only physisorbed molecules were found in the residue and lipids were more highly concentrated than proteins. The presence of lipids in the residue was found to be a consequence of damage to the plasma membrane during the rehydration process and the increased cell stress was also apparent by the amount of Hsp12 in the protein residue. The immobilized yeast cells on PIII-treated PTFE were found to be as active as yeast cells in suspension. 相似文献