全文获取类型
收费全文 | 2632篇 |
免费 | 66篇 |
专业分类
电工技术 | 46篇 |
综合类 | 4篇 |
化学工业 | 593篇 |
金属工艺 | 73篇 |
机械仪表 | 49篇 |
建筑科学 | 106篇 |
矿业工程 | 24篇 |
能源动力 | 97篇 |
轻工业 | 116篇 |
水利工程 | 25篇 |
石油天然气 | 7篇 |
无线电 | 181篇 |
一般工业技术 | 449篇 |
冶金工业 | 544篇 |
原子能技术 | 40篇 |
自动化技术 | 344篇 |
出版年
2022年 | 21篇 |
2021年 | 34篇 |
2019年 | 27篇 |
2018年 | 29篇 |
2017年 | 24篇 |
2016年 | 59篇 |
2015年 | 33篇 |
2014年 | 51篇 |
2013年 | 183篇 |
2012年 | 75篇 |
2011年 | 124篇 |
2010年 | 86篇 |
2009年 | 105篇 |
2008年 | 111篇 |
2007年 | 102篇 |
2006年 | 86篇 |
2005年 | 92篇 |
2004年 | 60篇 |
2003年 | 60篇 |
2002年 | 49篇 |
2001年 | 46篇 |
2000年 | 20篇 |
1999年 | 52篇 |
1998年 | 89篇 |
1997年 | 68篇 |
1996年 | 50篇 |
1995年 | 46篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 41篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 33篇 |
1988年 | 25篇 |
1987年 | 30篇 |
1986年 | 30篇 |
1985年 | 43篇 |
1984年 | 27篇 |
1983年 | 35篇 |
1982年 | 32篇 |
1981年 | 35篇 |
1980年 | 30篇 |
1979年 | 36篇 |
1978年 | 22篇 |
1977年 | 31篇 |
1976年 | 35篇 |
1975年 | 28篇 |
1974年 | 44篇 |
1972年 | 19篇 |
1955年 | 17篇 |
排序方式: 共有2698条查询结果,搜索用时 15 毫秒
1.
Elli Ntakou Ralph Masiello Farnaz Farzan Shay Bahramirad Aleksi Paaso M.A. Nayeem Maigha Maigha Daniel Kushner 《The Electricity Journal》2019,32(4):45-49
This paper presents part of the work ComEd and Quanta Technology have performed to quantify the locational and temporal value of DER to avoid distribution grid upgrade investments. It focuses on the formulation of a robust and efficient algorithm for DER optimal dispatch on a distribution feeder to mitigate the violation of current and voltage limits using the allocated cost of capacity and locational marginal value of real and reactive DER injection/withdrawal. 相似文献
2.
Pavel Strunz Debashis Mukherji Přemysl Beran Ralph Gilles Lukas Karge Michael Hofmann Markus Hoelzel Joachim Rösler Gergely Farkas 《Metals and Materials International》2018,24(5):934-944
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献
3.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry 相似文献
4.
Ralph Ralola 《今日电子》2006,(11):33-33
日本国家高级工业科学与技术研究所的一个研究组正在利用快速移动的细菌来驱动微转子马达,这是第一个在无机材料中加进了细菌的微机械器件。这种生物分子马达能比传统的马达更有效的将化学能转化为机械能,还能在大型结构中发挥自修复和自组织的潜能,有望用在微型机器人和微小电子系统中。 相似文献
5.
Planning is an essential function of project management. Yet, many small- and medium-sized contractors do a relatively poor job of operational planning. Better prebid plans will reduce costs, shorten schedules, and improve labor productivity. Unfortunately, the published literature offers little guidance for smaller contractors on what constitutes effective planning. Most papers describe planning as a macrolevel process for owners. Most emphasize scope definition for industrial projects. This paper describes a microlevel planning process for contractors. It consists of eight steps which are: (1) assess contract risks; (2) develop a preliminary execution plan; (3) develop site layout plans; (4) identify the sequences that are essential-to-success; (5) develop detailed operational plans; (6) develop proactive strategies to assure construction input into design; (7) revise the preliminary plan; and (8) communicate and enforce the plan. The entire process is illustrated with a case study project and is fully illustrated with figures which show how to integrate the work of multiple contractors, keep key resources (crews or equipment) fully engaged with no downtime, provide time buffers so the work of follow on crews can be efficiently done, expedite the schedule using multiple work stations and concurrent work, ways to communicate the work plan to the superintendent and foremen, and how to assess the feasibility of various work methods. The steps are easy to understand and implement. They will yield immediate positive results. 相似文献
6.
JA Burger A Ochs K Wirth DP Berger R Mertelsmann R Engelhardt M Roessle K Haag 《Canadian Metallurgical Quarterly》1997,8(2):200-202
BACKGROUND: The increase in portal vascular resistance is a significant complication of metastatic disease to the liver or locally advanced cancer, e.g., biliary cancer. PATIENTS AND METHODS: This paper describes the successful palliative treatment of two cancer patients with portal hypertension presenting with the symptoms of tense ascites, mesenteric congestion, and severe variceal bleeding. By creating a stenttract between a hepatic vein and a main branch of the portal vein and/or by placing an extendable stent into the portal vein, the transjugular intrahepatic portosystemic stent-shunt (TIPS) technique was used to decompress the portovascular system. RESULTS: The TIPS-technique offers a new, safe and effective palliation for malignant portal hypertension. In both patients, the symptoms of the portal hypertension disappeared after the procedure. This was accompanied by a significant improvement of the patients performance status allowing an early ambulation. CONCLUSION: Our findings demonstrate the feasibility and effectiveness of the TIPS procedure as a minimal invasive treatment for portal vein decompression in selected tumor patients. 相似文献
7.
8.
9.
INTRODUCTION: In a retrospective study a treatment concept for Perthes' disease dependent on the containment was applied. PATIENTS/METHODS: 49 hips of 41 children (9 female, 32 male) were treated between 01. 01. 1990 and 31. 12. 1995. In our concept of treatment a varus femoral osteotomy was performed in 28 cases with not contained hips or less than 4/5 coverage of the femoral head (X-ray/MRI). The other 21 well contained hips with 4/5 coverage or more were treated conservatively with physiotherapy and in case of joint effusion and pain additionally with the use of crutches (partial weight bearing) and anti-inflammatory medication. The average age in the non-operative group at the time of first investigation was 4 years and 9 months (3 y./1 m. to 7 y./1 m.) and 6 years and 3 months (4 y/2 m. to 10 y/0 m.) at our last examination (mean follow up 17.7 months, range of 6 to 72 months). At the time of indication for a varus femoral osteotomy the patients had an average age 6 years and 1 month (3 y./6 m. to 10 y./2 m.), the mean age at the last postoperative examination was 7 years and 11 months (4 y./8 m. to 12 y./5 m.) with an average follow up of 21.5 months (6 to 77 months). RESULTS: For the conservatively treated children we achieved good results (still well contained hips with 4/5 coverage, no decrease of function, no increase of pain) in 85.7% (18 of 21 cases). In 85.7% (24 of 28 cases) we found good results (well contained hips, increase of coverage, no decrease of function, no increase of pain) in the operation group. CONCLUSIONS: The presented concept of therapy in Perthes' disease was practicable for all patients and included the possibility of decision for operative or non-operative treatment. In both groups we achieved good results in 85.7% of the cases. 相似文献
10.
Ralph W. Pridmore 《Color research and application》2007,32(3):208-222
A color stimulus may be characterized by three psychophysical dimensions (luminance, dominant wavelength, and purity), whose corresponding color attributes are lightness, hue, and chroma/colorfulness. The 3 × 3 matrix gives nine basic effects of the psychophysical dimensions on the color attributes (e.g. the effect of luminance on hue), but there are 49 possible combinations as more complex effects (e.g. the effect of luminance on hue and chroma, i.e. on chromaticity). Researching and quantifying such effects enables modelling of the underlying neural mechanisms and of color appearance. Using a simple nomenclature to identify the effects (e.g. Ph denotes the effect of Purity on hue), this paper briefly reviews and interrelates 15 of the commonest effects, giving new data or new graphical perspectives to clarify or fill gaps in the literature. Contrast and no‐contrast effects (stimuli viewed simultaneously or singly, respectively) are differentiated. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 208–222, 2007 相似文献