全文获取类型
收费全文 | 853篇 |
免费 | 23篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 195篇 |
金属工艺 | 10篇 |
机械仪表 | 13篇 |
建筑科学 | 37篇 |
矿业工程 | 2篇 |
能源动力 | 11篇 |
轻工业 | 87篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 58篇 |
一般工业技术 | 148篇 |
冶金工业 | 188篇 |
原子能技术 | 12篇 |
自动化技术 | 99篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 51篇 |
2012年 | 22篇 |
2011年 | 34篇 |
2010年 | 30篇 |
2009年 | 32篇 |
2008年 | 32篇 |
2007年 | 40篇 |
2006年 | 26篇 |
2005年 | 30篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 21篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 17篇 |
1998年 | 50篇 |
1997年 | 36篇 |
1996年 | 21篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1978年 | 8篇 |
1977年 | 19篇 |
1976年 | 23篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1970年 | 6篇 |
1969年 | 10篇 |
排序方式: 共有878条查询结果,搜索用时 15 毫秒
71.
A pilot-scale subsurface vertical-flow wetland system was constructed at the former BP Refinery in Casper, Wyoming in order to determine benzene, toluene, ethylbenzene and xylene (BTEX) degradation rates in a cold-climate application. The pilot system, consisting of 4 cells, each dosed at a nominal flow rate of 5.4 cubic metres per day, was operated between August and December 2002. The pilot tested the effects of wetland mulch and aeration on system performance. Areal rate constants (kA values) were calculated based on an assumed three tanks in series (3TIS). The presence of wetland sod and aeration both improved treatment performance. Mean kA values were 244 m/yr for cells without sod or aeration, and improved to 356 m/yr for cells with sod and aeration. Based on the results of the pilot system, a full-scale wetland system (capable of operating at 6,000 m3/day) was started up in May 2003. The full-scale system achieved permit compliance within one week of startup, but is currently being loaded at only 45% of the design hydraulic load, and 15% of the design BTEX mass load, resulting in a mean kA value of approximately 350 m/yr. 相似文献
72.
73.
The varied definitions used in four studies of path controllability of linear input-output systems are given, their similarities and differences examined, and some of their corresponding results compared and discussed. 相似文献
74.
Schuster M. Klein N. Ruther P. Trautmann A. Paul O. Kuzel P. Kadlec F. 《Selected Areas in Communications, IEEE Journal on》2005,23(7):1378-1384
Due to their unique properties, electromagnetic bandgap (EBG) materials are of high interest for applications in communication technology for many frequency bands from microwave up to optical frequencies. We have investigated in both simulation and experiment a two dimensionally periodic EBG structure made by reactive ion etching of silicon with a bandgap for transverse magnetic waves in the millimeter wave range around 100 GHz. The structure comprises both a large bandgap and a high mechanical stability due to interconnecting dielectric bridges. 相似文献
75.
Akhrawat Lenwari Thaksin Thepchatri Pedro Albrecht 《Canadian Metallurgical Quarterly》2005,9(4):296-303
This paper presents the flexural behavior of rolled steel beams that were strengthened with partial-length, adhesive-bonded carbon fiber-reinforced polymer (CFRP) plates. The hybrid beams had two types of failure mode, depending on the length of the plate: (1) plate debonding in beams with short plates;?and (2) plate rupture at midspan in beams with long plates. The flexural behavior that was investigated includes the development of tensile stresses in the plate, the moment-curvature of the strengthened section, and the load-deflection of the strengthened beam. The analytical methods used include shear lag analysis, section analysis, and application of the virtual work principle. Agreement between the experimental results and the analytical predictions is discussed. 相似文献
76.
Albrecht E Gotoh T Ebara F Xu JX Viergutz T Nürnberg G Maak S Wegner J 《Meat science》2011,89(1):13-20
The experiment was conducted to study the development of intramuscular fat in Japanese Black (JB) compared to Holstein (HS) steers and to find breed differences for fat depot development and distribution in the carcass under equal feeding conditions. Additional to slaughter samples, biopsy samples of longissimus muscle (LM) and subcutaneous fat, taken at 10, 14, 18, and 22 months of age, were used for histological and molecular investigations. Japanese Black steers stored about 14% more fat in the LM (P = 0.001), resulting in larger marbling flecks (P < 0.001). Muscle fibers and intramuscular adipocytes in both breeds responded to the high energy feeding with significant enlargement, which was faster in JB. Histograms of intramuscular adipocytes size showed a shift toward larger cells during growth, but also the abundance of small, developing adipocytes. This development was accompanied by a correlated up-regulation of adipogenic genes until 22 months of age. 相似文献
77.
Cecchini MP Hong J Lim C Choo J Albrecht T Demello AJ Edel JB 《Analytical chemistry》2011,83(8):3076-3081
The development of ultrafast Raman-based detection is one of the most interesting challenges underpinning the application of droplet-based microfluidics. Herein, we describe the use of surface-enhanced resonance Raman spectroscopy (SERRS) with submillisecond time resolution as a powerful detection tool in microdroplet reactors. Individual droplets containing silver nanoparticle aggregates functionalized with Raman reporters are interrogated and characterized by full spectra acquisitions with high spatial resolution in real time. Whereas previous works coupling SERRS with droplet-based microfluidics acquire a single spectrum over single or multiple droplets, we build upon these results by increasing our temporal resolution by 2 orders of magnitude. This allows us to interrogate multiple points within one individual droplet. The SERRS signals emitted from the aggregates are utilized to access the influence of flow rate on droplet size and throughput. Accordingly, our approach allows for high-throughput analysis that facilitates the study of other biological assays or molecular interactions. 相似文献
78.
Electrophoretic DNA sequencing without a polymer matrix is currently possible only with the use of some kind of "drag-tag" as a mobility modifier. In free-solution conjugate electrophoresis (FSCE), a drag-tag attached to each DNA fragment breaks linear charge-to-friction scaling, enabling size-based separation in aqueous buffer alone. Here we report a 265-base read for free-solution DNA sequencing by capillary electrophoresis using a random-coil protein drag-tag of unprecedented length and purity. We identified certain methods of protein expression and purification that allow the production of highly monodisperse drag-tags as long as 516 amino acids, which are almost charge neutral (+1 to +6) and yet highly water-soluble. Using a four-color LIF detector, 265 bases could be read in 30 min with a 267-amino acid drag-tag, on par with the average read of current next-gen sequencing systems. New types of multichannel systems that allow much higher throughput electrophoretic sequencing should be much more accessible in the absence of a requirement for viscous separation matrix. 相似文献
79.
80.