全文获取类型
收费全文 | 1860篇 |
免费 | 25篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 127篇 |
金属工艺 | 3篇 |
机械仪表 | 20篇 |
建筑科学 | 37篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 152篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 77篇 |
一般工业技术 | 134篇 |
冶金工业 | 1207篇 |
原子能技术 | 15篇 |
自动化技术 | 78篇 |
出版年
2021年 | 9篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 16篇 |
2016年 | 7篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 29篇 |
2012年 | 42篇 |
2011年 | 35篇 |
2010年 | 28篇 |
2009年 | 30篇 |
2008年 | 41篇 |
2007年 | 43篇 |
2006年 | 27篇 |
2005年 | 31篇 |
2004年 | 21篇 |
2003年 | 19篇 |
2002年 | 20篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 59篇 |
1998年 | 379篇 |
1997年 | 218篇 |
1996年 | 140篇 |
1995年 | 76篇 |
1994年 | 80篇 |
1993年 | 76篇 |
1992年 | 12篇 |
1991年 | 21篇 |
1990年 | 19篇 |
1989年 | 19篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 23篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1980年 | 16篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 25篇 |
1976年 | 66篇 |
1975年 | 7篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1970年 | 5篇 |
排序方式: 共有1886条查询结果,搜索用时 15 毫秒
61.
There is a need to develop effective stormwater filters for passive (without any addition of chemicals or energy) and effective removal of pathogens in order to mainstream stormwater harvesting. This study focuses on the development of coated granular activated carbon (GAC) filtration material in order to develop filters for effective removal of pathogens from urban stormwater. Several laboratory trials were performed to gauge the effectiveness of the filters, which use a mixture of the zinc-sulphate-heptahydrate coated GAC and sand, on the removal of Escherichia coli (E. coli) from semi-natural stormwater. On average, a 98% removal of the inflow concentration of E. coli was achieved. Furthermore, there was also an improvement of approximately 25% in the removal of phosphorous. However, it was found that the treated material was leaching zinc. It was important to determine whether the observed removal of E. coli was indirectly caused by the sampling methodology. The results showed that the inactivation of the E. coli in the collected sample was small compared with the inactivation which actually occurred within the filter. This provides much promise to the filter, but the presence of zinc in the outflow demonstrates the need for further investigation into the stabilisation of the coating process. 相似文献
62.
Netto I Bostan V McCarthy L Laursen A Gilbride K Mehrvar M Pushchak R 《Water science and technology》2012,66(8):1708-1715
The short-term impacts of atrazine (herbicide), tributyltin (organometal) and copper on the behaviour of Euglena gracilis Klebs (Euglenophyta) were assessed. First, the ECOTOX automated image analysis system was used, which measured swimming velocity, cell shape, percentage of cells swimming upwards, and randomness of swimming. Next, visual observation by microscopy was used to measure percentage of cell motility and cell shape. Behavioural changes can be used as an indicator of stress in less than 24 h, potentially making them suitable for inclusion in early-warning systems for water quality. Findings indicate that E. gracilis is a very sensitive organism to copper, showing inhibition of motility with visual observation at 0.8 μmol/L within 1 h. The image analysis system was in general less sensitive than visual observation for detecting behavioural changes after incubation in copper. In contrast, after exposure to organic contaminants atrazine and tributyltin, the ECOTOX system detected small changes in the number of cells swimming upwards (antigravitactic behaviour) at higher concentrations. 相似文献
63.
Baião D Medina F Ochando M McCarthy K Tabarés F Pastor I Varandas C 《The Review of scientific instruments》2012,83(5):053501
The core electron temperature (T(e0)) of neutral beam heated plasmas is determined in TJ-II stellarator by using soft x ray detectors with beryllium filters of different thickness, based on the method known as the foil absorption technique. T(e0) estimations are done with the impurity code IONEQ, making use of complementary information from the TJ-II soft x ray tomography and the VUV survey diagnostics. When considering the actual electron density and temperature profile shapes, an acceptable agreement is found with Thomson scattering measurements for 8 different magnetic configurations. The impact of the use of both neutral beam injectors on the T(e0) measurements is addressed. Also, the behaviour of T(e0) during spontaneous profile transitions is presented. 相似文献
64.
We have examined the 3'-terminal sequence of the "small" structural ribosomal RNA ("13S") of hamster cell mitochondria, using a procedure involving [3H]isoniazide labeling of samples subjected to sequential periodate oxidation and beta-elimination. The terminus was found to be PyUAUUAOH, which is similar, but not identical, to the corresponding terminus of eukaryotic cytoplasmic 18S rRNA. 相似文献
65.
Dora Y. Chakraborty A. Heikman S. McCarthy L. Keller S. DenBaars S.P. Mishra U.K. 《Electron Device Letters, IEEE》2006,27(7):529-531
The effect of ohmic contacts on the buffer leakage of GaN transistors is presented. The buffer leakage for AlGaN/GaN high-electron mobility transistors and GaN MESFETs grown on the same underlying buffer was observed to be different. Controlled experiments show that the increased buffer leakage is due to the nature of the alloyed ohmic contacts and can be minimized if they are screened by the Si doping or by the two-dimensional electron gas. 相似文献
66.
M. A. McCarthy J. R. Xiao C. T. McCarthy A. Kamoulakos J. Ramos J. P. Gallard V. Melito 《Applied Composite Materials》2004,11(5):317-340
Fibre Metal Laminates with layers of aluminium alloy and high strength glass fibre composite have been reported to possess excellent impact properties and be suitable for aircraft parts likely to be subjected to impacts such as runway debris or bird strikes. In a collaborative research project, aircraft wing leading edge structures with a glass-based FML skin have been designed, built, and subjected to bird strike tests that have been modelled with finite element analysis. In this second part of a two-part paper, a finite element model is developed for simulating the bird strike tests, using Smooth Particle Hydrodynamics (SPH) for modelling the bird and the material model developed in Part 1 of the paper for modelling the leading edge skin. The bird parameters are obtained from a system identification analysis of strikes on flat plates. Pre-test simulations correctly predicted that the bird did not penetrate the leading edge skin, and correctly forecast that one FML lay-up would deform more than the other. Post test simulations included a model of the structure supporting the test article, and the predicted loads transferred to the supporting structure were in good agreement with the experimental values. The SPH bird model showed no signs of instability and correctly modelled the break-up of the bird into particles. The rivets connecting the skin to the ribs were found to have a profound effect on the performance of the structure. 相似文献
67.
Elham Khanipour Steve H. Flint Owen J. McCarthy Matt Golding Jon Palmer Mark Tamplin 《International Journal of Food Science & Technology》2014,49(6):1506-1512
The aim of this study was to evaluate the combined effect of salt (sodium chloride, 0–8% w/v), sorbate (potassium sorbate, 0–4.5% w/v), nisin (0–500 ppm) and lysozyme (0–500 ppm) on the survival of Clostridium sporogenes as a non‐toxigenic surrogate of Clostridium botulinum in terms of the probability of growth by using a central composite rotatable design. The results indicated that salt and sorbate were the most effective factors in preventing the growth of Cl. sporogenes in high‐moisture (>95%) and low‐acid conditions. The probability of growth of Cl. sporogenes in broth was reduced by combinations of salt and sorbate. Nisin and lysozyme had insignificant effects on the probability of growth of Cl. sporogenes (P > 0.05). Lysozyme individually and in combination with nisin had no inhibitory effect on Cl. sporogenes. Overall, the addition of sorbate and lysozyme may allow the salt concentration to be reduced while preventing growth. 相似文献
68.
69.
The purposes of this study were to (1) explore significant differences in perception of match for a variety of food and wine styles; (2) evaluate the impacts of wine sweetness level, wine acidity level, and wine tannin level on perception of match; and (3) investigate the impact of food and wine expertise on perceived level of match. The highest perceived wine matches for each food item were: Sauvignon Blanc and chêvre, Chardonnay and brie, Cabernet Sauvignon and spicy Italian salami, and Port and milk chocolate. Wine sweetness, acidity, and tannin levels all significantly impacted the level of match with certain food items. Food and wine expertise also significantly impacted the level of match, indicating differences between the more expert and novice participants in the role wine sweetness, acidity, and tannin had on level of match. 相似文献
70.