全文获取类型
收费全文 | 1058篇 |
免费 | 57篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 118篇 |
金属工艺 | 5篇 |
机械仪表 | 8篇 |
建筑科学 | 28篇 |
矿业工程 | 2篇 |
能源动力 | 14篇 |
轻工业 | 220篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 135篇 |
一般工业技术 | 163篇 |
冶金工业 | 336篇 |
原子能技术 | 8篇 |
自动化技术 | 56篇 |
出版年
2023年 | 5篇 |
2022年 | 16篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 22篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 24篇 |
2013年 | 24篇 |
2012年 | 31篇 |
2011年 | 40篇 |
2010年 | 33篇 |
2009年 | 25篇 |
2008年 | 39篇 |
2007年 | 38篇 |
2006年 | 41篇 |
2005年 | 27篇 |
2004年 | 26篇 |
2003年 | 24篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 19篇 |
1999年 | 23篇 |
1998年 | 100篇 |
1997年 | 68篇 |
1996年 | 58篇 |
1995年 | 26篇 |
1994年 | 26篇 |
1993年 | 20篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有1116条查询结果,搜索用时 15 毫秒
81.
Frontal affinity chromatography (FAC) interfaced with electrospray mass spectrometry (ESI-MS) has been reported as a potential method for screening of compound mixtures against immobilized target proteins. However, the interfacing of bioaffinity columns to ESI-MS requires that the eluent that passes through the protein-loaded column have a relatively low ionic strength to produce a stable spray. Such low ionic strength solvents can cause serious problems with protein stability and may also affect binding constants and lead to high nonspecific binding to the column. Herein, we report on the interfacing of bioaffinity columns to matrix-assisted laser desorption/ionization (MALDI) MS/MS as a new platform for FAC/MS studies. Capillary columns containing a monolithic silica material with entrapped dihydrofolate reductase were used for frontal affinity chromatography of small-molecule mixtures. The output from the column was combined with a second stream containing alpha-cyano-hydoxycinnamic acid in methanol and was deposited using a nebulizer-assisted electrospray method onto a conventional MALDI plate that moved relative to the column via a computer-controlled x-y stage, creating a semipermanent record of the FAC run. The use of MALDI MS/MS allowed for buffers with significantly higher ionic strength to be used for FAC studies, which reduced nonspecific binding of ionic compounds and allowed for better retention of protein activity over multiple runs. Following deposition, MALDI analysis required only a fraction of the chromatographic run time, and the deposited track could be rerun multiple times to optimize ionization parameters and allow signal averaging to improve the signal-to-noise ratio. Furthermore, high levels of potential inhibitors could be detected via MALDI with limited ion suppression effects. Both MALDI- and ESI-based analysis showed similar retention of inhibitors present in compound mixtures when using identical ionic strength conditions. The results show that FAC/MALDI-MS should provide advantages over FAC/ESI-MS for high-throughput screening of compound mixtures. 相似文献
82.
83.
Zeinab Dehghan‐Shoar Allan K. Hardacre Gerrit Meerdink Charles S. Brennan 《International Journal of Food Science & Technology》2011,46(2):365-371
To determine the lycopene content of extruded products containing 10% tomato skin, the conditions for solvent extraction were optimised. After three extraction cycles at 50 °C each for 15 min at a solvent to meal ratio of 40:1, a maximum of 6.6 ppm lycopene was extracted. However, the extraction was considered incomplete, thus the product was digested by pancreatin prior to extraction. The extracted lycopene content was increased to 23.5 ppm using the optimum conditions of 20 min of digestion with 10 mg mL?1 pancreatin. To validate the extraction efficiency at optimum conditions, a set of extruded products containing different lycopene concentrations was used. Digestion increased the extracted lycopene content by more than 2.5‐fold between the products. Furthermore, this inclusion significantly improved the correlation coefficient between the red colour and the extracted lycopene content. Therefore, including a digestion step prior to extraction by solvents was necessary to efficiently extract lycopene from extruded products. 相似文献
84.
85.
Oni Yuliarti Lara Matia‐Merino Kelvin T. Goh John Mawson Charles Brennan 《International Journal of Food Science & Technology》2012,47(3):633-639
Pectin was extracted from gold kiwifruit by four commercial enzyme preparations (Celluclast 1.5 L, Cytolase CL, Cellulyve TR 400 and NS33048). The chosen enzymes were used either in single or in combination, with and without protease addition. The recovered pectin was characterised and compared for the yield, total nonstarch polysaccharide and neutral sugar composition, protein and ash, pectin, molecular weight distribution and the viscosity. Results indicated that enzyme‐extracted gold kiwifruit pectin was rich in galacturonic acid. Purified pectin yield, and their physicochemical composition and rheological property (viscosity), was significantly affected by the type of enzyme used. The pectin extracted by Celluclast 1.5 L demonstrated to be the most viscous and recorded the highest in molecular weight (Mw) (1.65 × 106 g mol–1) compared with the other extracts. The extract Mw and their distribution were discussed and related to their viscosity behaviour. 相似文献
86.
Kevin F. Brennan Joe HaralsonII Joseph W. ParksJr Ali Salem 《Microelectronics Reliability》1999,39(12):335
In this paper, we present a brief review of the principal mechanisms that influence the reliability of metal–semiconductor–metal (MSM) interdigitated photodetectors and avalanche photodiodes (APD). The most important mechanism influencing reliability in these devices is the dark current. However, other mechanisms such as edge and microplasmic breakdown and electrode degradation, can also affect device reliability. In this study, we describe numerical simulation techniques that can be utilized to understand the workings of some of these mechanisms and illustrate their usage in a few representative devices. Specifically, we discuss how advanced drift-diffusion and hydrodynamic simulation techniques can be used to study the dark current as well as the location of breakdown in MSM and APD devices. 相似文献
87.
88.
Frederick Steiner Laurel McSherry Dean Brennan Mark Soden Joe Yarchin Douglas Green 《Journal of the American Planning Association. American Planning Association》2013,79(2):207-222
As part of ongoing cooperation between the City of Phoenix and Arizona State University, a charrette was organized. Planners, landscape architects, environmental scientists, and architects explored concepts for development within a 110-square-mile (285-km2) portion of Phoenix. The charrette was the summation of over a year of environment studies of the planning area. This part of northern Phoenix occupies a largely undeveloped upper Sonoran desert landscape experiencing intense development pressure. Four charrette teams addressed desert preservation, rural desert development, suburban desert development, and growth corridors. This article focuses on some of the strategies proposed by the suburban desert development team. One of these called for an alternative pattern of development aligned with natural drainage corridors. Several concepts from the charrette and findings from the environmental research were adopted by the City in the revised general plan for the area. 相似文献
89.
A statistical algorithm has been developed to compensate for the fixed-pattern noise associated with spatial nonuniformity and temporal drift in the response of focal-plane array infrared imaging systems. The algorithm uses initial scene data to generate initial estimates of the gain, the offset, and the variance of the additive electronic noise of each detector element. The algorithm then updates these parameters by use of subsequent frames and uses the updated parameters to restore the true image by use of a least-mean-square error finite-impulse-response filter. The algorithm is applied to infrared data, and the restored images compare favorably with those restored by use of a multiple-point calibration technique. 相似文献
90.
Markys G. Cain Rebecca L. Cain Michael H. Lewis John Gent 《Journal of the American Ceramic Society》1997,80(7):1873-1876
A novel in situ reaction between a ceria-doped zirconia interphase coating on Saphikon fibers and an outer alumina coating has resulted in the formation of oriented hexaaluminate platelets which can act as a low fracture energy interface barrier for crack deflection in oxide-oxide ceramic-matrix composites (CMCs). The reaction proceeds only in reducing environments where the reduction of the cerium and zirconium ions to their 3+ valent state causes a destabilization phenomenon consistent with previously reported findings. The diffusion of the cerium from the zirconia into solid solution with the alumina can stabilize the layered hexaaluminate structure. Preferred orientational growth of the hexaaluminate parallel to the coating interface was observed which is the required orientation for enhanced debonding at the fiber/matrix interface in long-fiber-reinforced CMCs. 相似文献