全文获取类型
收费全文 | 707篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 132篇 |
金属工艺 | 7篇 |
机械仪表 | 22篇 |
建筑科学 | 40篇 |
能源动力 | 31篇 |
轻工业 | 42篇 |
水利工程 | 6篇 |
无线电 | 41篇 |
一般工业技术 | 202篇 |
冶金工业 | 80篇 |
原子能技术 | 2篇 |
自动化技术 | 121篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 14篇 |
2017年 | 16篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 41篇 |
2012年 | 38篇 |
2011年 | 48篇 |
2010年 | 33篇 |
2009年 | 49篇 |
2008年 | 56篇 |
2007年 | 42篇 |
2006年 | 35篇 |
2005年 | 39篇 |
2004年 | 20篇 |
2003年 | 26篇 |
2002年 | 17篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 9篇 |
1998年 | 31篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有729条查询结果,搜索用时 15 毫秒
111.
Inter‐organizational collaboration is increasingly a topic for studies into accidents and disasters as well as exercises. In this study, which is based on interviews with first responders, we compared perceived collaboration during an exercise with crisis work. The three organizations included in this study—fire department, police and ambulance services—perceived the investigated tunnel exercise completely different, ranging from harmonious interaction to power struggles between commanding officers, fragmented decision‐making and ambiguity. When comparing the exercise with an incident, we found that collaboration was more evident during incidents than in exercises. However, collaboration exercises appear to improve inter‐organizational collaboration by stimulating informal structures, practicing listening and delegating, getting to know one another and learning a common language. 相似文献
112.
Mirjana Dimitrievska Fredrik S. Hage Simon Escobar Steinvall Alexander P. Litvinchuk Elias Z. Stutz Quentin M. Ramasse Anna Fontcuberta i Morral 《Advanced functional materials》2021,31(41):2105426
Earth-abundant and environmentally friendly semiconductors offer a promising path toward low-cost mass production of solar cells. A critical aspect in exploring new semiconducting materials and demonstrating their enhanced functionality consists in disentangling them from the artifacts of defects. Nanowires are diameter-tailored filamentary structures that tend to be defect-free and thus ideal model systems for a given material. Here, an additional advantage is demostrated, which is the determination of the band structure, by performing high energy and spatial resolution electron energy-loss spectroscopy in aloof and inner beam geometry in a scanning transmission electron microscope. The experimental results are complemented by spectroscopic ellipsometry and are excellently correlated with first principles calculations. This study opens the path for characterizing the band structure of new compounds in a non-destructive and prompt manner, strengthening the route of new materials discovery. 相似文献
113.
Ella Kolkowska Fredrik Karlsson Karin Hedström 《The Journal of Strategic Information Systems》2017,26(1):39-57
Employees’ poor compliance with information security policies is a perennial problem. Current information security analysis methods do not allow information security managers to capture the rationalities behind employees’ compliance and non-compliance. To address this shortcoming, this design science research paper suggests: (a) a Value-Based Compliance analysis method and (b) a set of design principles for methods that analyse different rationalities for information security. Our empirical demonstration shows that the method supports a systematic analysis of why employees comply/do not comply with policies. Thus we provide managers with a tool to make them more knowledgeable about employees’ information security behaviours. 相似文献
114.
Fredrik Berthold Kristina Gustafsson Rickard Berggren Elisabeth Sjholm Mikael Lindstrm 《应用聚合物科学杂志》2004,94(2):424-431
A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N‐dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high‐molecular‐mass material and increased the proportion of the low‐molecular‐mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a κ number of around 50. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 424–431, 2004 相似文献
115.
This article examines export propensities among Indonesian manufacturers. The pattern of trade between nations is well understood, but much less is known about firm level determinants to export: why do some Indonesian firms start to export while others continue to produce for the domestic market? One reason for different export propensities could be that the sunk costs for exports differ between firms. This article examines if foreign networks decrease export-costs and thereby have a positive impact on the export propensity in Indonesian manufacturing establishments. Three different types of foreign networks are examined: foreign ownership, import, and the regional presence of Foreign Direct Investment (FDI).Received: 31 January 2002, Accepted: 27 November 2002, JEL Classification:
F10, F23, L10 相似文献
116.
This paper deals with the allocation of public investments to some of the prospective key elements in the regional infrastructure. Two optimization models are suggested for allocating investment resources among regions and various infrastructure elements. Applications of the models illustrate solutions based on policy goals of economic efficiency and regional equity. The optimization models draw on the estimation of an aggregate regional production function. 相似文献
117.
Saarela KE Harju L Rajander J Lill JO Heselius SJ Lindroos A Mattsson K 《The Science of the total environment》2005,343(1-3):231-241
Bark and wood samples were taken from the same individuals of Scots pine (Pinus sylvestris L.) from a polluted area close to a Cu-Ni smelter in Harjavalta and from some relatively unpolluted areas in western Finland. The samples were analysed by thick-target particle induced X-ray emission (PIXE) after preconcentration by dry ashing at 550 degrees C. The elemental contents of pine bark and wood were compared to study the impact of heavy metal pollution on pine trees. By comparison of the elemental contents in ashes of bark and wood, a normalisation was obtained. For the relatively clean areas, the ratios of the concentration in bark ash to the concentration in wood ash for different elements were close to 1. This means that the ashes of Scots Pine wood and bark have quite similar elemental composition. For the samples from the polluted area the mean concentration ratios for some heavy metals were elevated (13-28), reflecting the effect of direct atmospheric contamination. The metal contents in the ashes of pine bark and wood were also compared to recommendations for ashes to be recycled back to the forest environment. Bark from areas close to emission sources of heavy metal pollution should be considered with caution if aiming at recycling the ash. Burning of bark fuel of pine grown within 6 km of the Cu-Ni smelter is shown to generate ashes with high levels of Cu, Ni as well as Cd, As and Pb. 相似文献
118.
119.
A set of monolithic stationary phases representing a broad span of monomers and porogens have been characterized directly in their capillary chromatographic format by computational assessment of their pore structure from transmission electron micrographs obtained after in situ embedment of the monoliths in contrast resin, followed by dissolution of the fused-silica tubing, further encasement of the resin-embedded monolith, and microtomy. This technique has been compared to mercury intrusion, a more conventional technique for macroporosity estimation. Supplementing the embedding resin by lead methacrylate gave a negative staining, and the resulting micrographs showed a good contrast between the polymeric monoliths and the embedding resin that allowed studies on the pore formation and polymer development. The technique was also applied to a commercial monolithic silica column. 相似文献
120.
Electrochemical impedance spectroscopy was employed to explore the possibility of relating the permeation of electrolyte ions in omega-functionalized self-assembled monolayers to structural or polarity changes induced by interaction with metal ions. The monolayers were based on alkanethiols modified with a phosphorylated tyrosine analogue, which from previous work are known to drastically change their organization on gold surfaces upon interaction with aluminum and magnesium ions. The ion permeation was evaluated by using relatively low excitation frequencies, 1000 to 2 Hz, and quantified by an extra resistive component in the equivalent circuit (RSAM). The extent of ion permeation influenced by the dc potential, the electrolyte concentration, the functional group, and the thiol length were also investigated. It was, for example, found that RSAM decreased approximately 20% when the thiol organization collapsed and that RSAM increased approximately 4-5 times when the electrolyte concentration was decreased by 1 order of magnitude. Interesting observations were also made regarding the potential dependence of RSAM and the double layer capacitance. The evaluation of the ion permeation can be used to indirectly detect whether the organization of a SAM is influenced by, for example, electric fields or chemical and biological interactions. This analysis can be performed without addition of redox species, but is on the other hand complicated by the fact that other factors also influence the presence of ions within the monolayer. In addition, a second parallel RC process was obtained in some of the impedance spectra when using even lower frequencies, and its resistive component revealed different results compared to RSAM. Such data may be useful for the understanding of complex double layer phenomena at modified electrodes. 相似文献