全文获取类型
收费全文 | 1120篇 |
免费 | 46篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 15篇 |
综合类 | 3篇 |
化学工业 | 252篇 |
金属工艺 | 7篇 |
机械仪表 | 17篇 |
建筑科学 | 65篇 |
矿业工程 | 4篇 |
能源动力 | 92篇 |
轻工业 | 130篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 50篇 |
一般工业技术 | 211篇 |
冶金工业 | 64篇 |
原子能技术 | 13篇 |
自动化技术 | 235篇 |
出版年
2023年 | 15篇 |
2022年 | 12篇 |
2021年 | 29篇 |
2020年 | 19篇 |
2019年 | 24篇 |
2018年 | 25篇 |
2017年 | 22篇 |
2016年 | 31篇 |
2015年 | 28篇 |
2014年 | 50篇 |
2013年 | 85篇 |
2012年 | 60篇 |
2011年 | 83篇 |
2010年 | 75篇 |
2009年 | 46篇 |
2008年 | 68篇 |
2007年 | 81篇 |
2006年 | 64篇 |
2005年 | 40篇 |
2004年 | 57篇 |
2003年 | 39篇 |
2002年 | 30篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 20篇 |
1998年 | 15篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有1168条查询结果,搜索用时 281 毫秒
91.
Jesper Mller Jakob Lichtenberg Henrik R. Andersen Henrik Hulgaard 《Electronic Notes in Theoretical Computer Science》2001,23(2)
Current approaches for analyzing timed systems are based on an explicit enumeration of the discrete states and thus these techniques are only capable of analyzing systems with a handful of timers and a few thousand states. We address this limitation by describing how to analyze a timed system fully symbolically, i.e., by representing sets of discrete states and their associated timing information implicitly. We demonstrate the efficiency of the symbolic technique by computing the set of reachable states for a non-trivial timed system and compare the results with the state-of-the-art tools Kronos and Uppaal. With an implementation based on difference decision diagrams, the runtimes are several orders of magnitudes better. The key operation in obtaining these results is the ability to advance time symbolically. We show how to do this efficiently by essentially quantifying out a special variable z which is used to represent the constant zero. The symbolic manipulations given in this paper are sufficient to verify TCTL-formulae fully symbolically. 相似文献
92.
Simon M. M. Pedersen Caroline Nebel Niels Chr. Nielsen Henrik J. Andersen Johan Olsson Magnus Simrén Lena Öhman Ulla Svensson Hanne C. Bertram Anders Malmendal 《European Food Research and Technology》2011,233(6):1013-1021
In the present study, the use of gas chromatography mass spectrometry (GC–MS)-based metabonomics to characterize blood serum
in an intervention study of patients suffering from the common gastrointestinal disorder irritable bowel syndrome (IBS) was
investigated. The patients included in the study consumed an acidified milk product with (n = 30) or without probiotics (n = 31) (Lactobacillus paracasei F19, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) for an 8-week period, and blood serum samples were collected before and after the intervention. Acidified milk is
commonly used as a delivering vector for probiotics in commercial consumer settings. The serum samples were extracted and
derivatized using N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and GC–MS analysis was carried out. Multivariate data analysis including principal
component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and S-plot was applied on the
obtained GC–MS data, which revealed higher serum lactate, glutamine, proline creatinine/creatine, and aspartic acid levels
and lower serum glucose levels after the intervention period for both treatment groups. Consequently, the present study indicated
an effect of acidified milk consumption on the plasma metabolite profile, which was independent of a concomitant intake of
probiotics. In addition, the present study demonstrates that GC–MS is a useful analytical technique for metabonomics studies
of blood serum. 相似文献
93.
94.
Klas Engvall Henrik Kusar Krister Sjöström Lars J. Pettersson 《Topics in Catalysis》2011,54(13-15):949-959
The depletion of fossil fuel-based resources and concerns for increasing emissions of CO2 call for new ways of producing environmentally-friendly substitutes for motor fuels and chemicals. Thermo-chemical conversion of biomass and waste using gasification is a strong candidate to meet these challenges. For efficient and cost-effective application of this technique, novel solutions for hot gas cleaning are needed. This review highlights some important areas for improvement of upgrading technologies for pressurised fluidised bed gasification systems using biomass as a fuel. 相似文献
95.
Arild Hoff Henrik Andersson Marielle Christiansen Geir Hasle Arne Løkketangen 《Computers & Operations Research》2010,37(12):2041-2061
The purpose of this paper is to describe industrial aspects of combined fleet composition and routing in maritime and road-based transportation, and to present the current status of research in the form of a comprehensive literature review. First, presents a classification of problems, and then focuses on a basic definition of combined fleet composition and routing: the fleet size and mix vehicle routing problem. A basic mathematical formulation from the literature is presented. Further, the literature of extended and related problems is described and categorized. Surveys of application oriented research in road-based and maritime transportation conclude the review. Finally, we contrast the literature with aspects of industrial applications from a critical, but constructive stance. Major issues for future work are suggested. 相似文献
96.
0-18 nm-thick titanium, zirconium and tantalum oxide films are thermally evaporated on Nafion 117 membranes, and used as thin spacer electrolyte layers between the Nafion and a 3 nm Pt catalyst film. Electrochemical characterisation of the films in terms of oxygen reduction activity, high frequency impedance and cyclic voltammetry in nitrogen is performed in a fuel cell at 80 °C and full humidification. Titanium oxide films with thicknesses up to 18 nm are shown to conduct protons, whereas zirconium oxide and tantalum oxide block proton transport already at a thickness of 1.5 nm. The performance for oxygen reduction is higher for a bi-layered film of 3 nm platinum on 1.5 or 18 nm titanium oxide, than for a pure 3 nm platinum film with no spacer layer. The improvement in oxygen reduction performance is ascribed to a higher active surface area of platinum, i.e. no beneficial effect of combining platinum with zirconium, tantalum or titanium oxides on the intrinsic oxygen reduction activity is seen. The results suggest that TiO2 may be used as electrolyte in fuel cell electrodes, and that low-temperature proton exchange fuel cells could be possible using TiO2 as electrolyte. 相似文献
97.
98.
99.
Sulfur has for long been known as a problematic element for the quality of iron, but along with its accumulation it also causes physical problems in the blast furnace, so it is of central importance to safeguard its removal from the process. Sulfur‐related problems in the blast furnace were studied by applying a balance equation for the element at three industrial blast furnaces, tracking errors in the in‐ and outflows and estimating changes in the amount of accumulated sulfur. A hypothesis on the behaviour of sulfur in the process was proposed and supporting evidence of it was found through an analysis of dynamic phenomena in the hearth of one of the furnaces. 相似文献
100.
Hanne Løje Kristina N Jensen Grethe Hyldig Henrik H Nielsen Jette Nielsen 《Journal of the science of food and agriculture》2007,87(14):2684-2691
BACKGROUND: During recent years, increases in liquid loss and soft texture in cold smoked salmon have been reported, possibly due to increased lipid content and a change in muscle structure. These problems can lead to downgrading of the product. This study aimed to investigate the influence of raw material composition and chill storage on quality parameters of cold smoked salmon. RESULTS: Initial smoked fish had a higher liquid‐holding capacity (LHC) than samples stored for 20 days. Large fish lost more liquid than small fish. The difference in LHC was consistent with a change in water distribution, which could indicate denaturation of muscle protein. Studies of the microstructure showed the influence of both processing and chill storage. An indication of lipid released from the cells was seen after 20 days of chill storage, which could be related to the reduced LHC at that time. CONCLUSION: Both raw material composition and chill storage affected the quality parameters of smoked salmon. This study has improved knowledge about the relationships between muscle structure, liquid‐holding properties and water distribution in smoked salmon. Copyright © 2007 Society of Chemical Industry 相似文献