首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   226篇
  免费   4篇
工业技术   230篇
  2023年   1篇
  2022年   1篇
  2021年   3篇
  2020年   1篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   9篇
  2013年   9篇
  2012年   8篇
  2011年   9篇
  2010年   6篇
  2009年   8篇
  2008年   10篇
  2007年   10篇
  2006年   10篇
  2005年   8篇
  2004年   6篇
  2003年   9篇
  2002年   3篇
  2001年   3篇
  2000年   5篇
  1999年   8篇
  1998年   20篇
  1997年   22篇
  1996年   9篇
  1995年   9篇
  1994年   5篇
  1993年   6篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1985年   2篇
  1984年   1篇
  1980年   2篇
  1979年   1篇
  1977年   3篇
  1976年   8篇
  1975年   2篇
排序方式: 共有230条查询结果,搜索用时 28 毫秒
1.
Sulphonated anthraquinones are known to be recalcitrant to biodegradation and are not eliminated by traditional wastewater treatment plants, leading to their accumulation in fresh water. Due to the high cost and limited efficiency of existing physical-chemical treatments, alternative cheaper processes are required to remove these compounds from industrial effluents. Four plant species were tested under hydroponic conditions for their ability to treat model effluents contaminated with mono- and disulphonated anthraquinones. Among them, Rheum rabarbarum (rhubarb) showed the most promising results and was chosen for further investigation. The apparent transpiration stream concentration factor obtained with this plant species reached up to 2.5, indicating a strong phytotreatment potential that should be further explored then exploited.  相似文献   
2.
This paper presents an original method developed to quantify the reactivity of mineral additions based on the measurement of the lime (CaO) and gypsum (CaSO4, 2H2O) consumed by mineral additions in a paste. Three mineral additions were tested: a Siliceous Filler (SF), a natural pozzolan (Poz) and a Wastepaper Sludge Ash (WSA). The results obtained on SF, considered as a reference, show the efficiency of this method. Its application to Poz and WSA permits the quantity of lime and gypsum consumed by these additions to be evaluated and, thus, the amount of each component to be optimized in Hydraulic Road Binders.  相似文献   
3.
EUROFER weldability is investigated in support of the European material properties database and TBM manufacturing. Electron Beam, Hybrid, laser and narrow gap TIG processes have been carried out on the EUROFER-97 steel (thickness up to 40 mm), a reduced activation ferritic-martensitic steel developed in Europe. These welding processes produce similar welding results with high joint coefficients and are well adapted for minimizing residual distortions. The fusion zones are typically composed of martensite laths, with small grain sizes. In the heat-affected zones, martensite grains contain carbide precipitates. High hardness values are measured in all these zones that if not tempered would degrade toughness and creep resistance. PWHT developments have driven to a one-step PWHT (750 °C/3 h), successfully applied to joints restoring good material performances. It will produce less distortion levels than a full austenitization PWHT process, not really applicable to a complex welded structure such as the TBM. Different tungsten coatings have been successfully processed on EUROFER material. It has shown no really effect on the EUROFER base material microstructure.  相似文献   
4.
This paper presents the insulated TO-220AB TRIAC package aging when these devices are subjected to experimental power cycling test with various case temperature swings (ΔTcase). This study includes reliability tests set-up, results and failure analysis. An innovative failure analysis flow is proposed to identify the failure mechanism implied. This new failure analysis process flow is necessary due to the complex stack of these devices. Finally, thanks to the reliability tests and the complete failure analysis results, the thermal resistance (Rth) change is correlated to the physical defect modification. This whole study gives the first data collection that is required to propose a lifetime prediction model for insulated TO-220AB TRIAC package during power cycling accelerated aging tests.  相似文献   
5.
This paper is concerned with the computation of the skeleton of a shape Ω included in ?2. We show some connections between the Euclidean distance function d to and the solution u of the Poisson problem Δu(x)=?1 if x is in Ω and u(x)=0 if x is on . This enables us to propose a new and fast algorithm to compute an approximation of the skeleton of . We illustrate the approach with some numerical experiments.  相似文献   
6.
The function of the central cannabinoid receptor (CB1) was investigated by invalidating its gene. Mutant mice did not respond to cannabinoid drugs, demonstrating the exclusive role of the CB1 receptor in mediating analgesia, reinforcement, hypothermia, hypolocomotion, and hypotension. The acute effects of opiates were unaffected, but the reinforcing properties of morphine and the severity of the withdrawal syndrome were strongly reduced. These observations suggest that the CB1 receptor is involved in the motivational properties of opiates and in the development of physical dependence and extend the concept of an interconnected role of CB1 and opiate receptors in the brain areas mediating addictive behavior.  相似文献   
7.
In this paper, we focus on statistical region-based active contour models where image features (e.g. intensity) are random variables whose distribution belongs to some parametric family (e.g. exponential) rather than confining ourselves to the special Gaussian case. In the framework developed in this paper, we consider the general case of region-based terms involving functions of parametric probability densities, for which the anti-log-likelihood function is a special case. Using shape derivative tools, our effort focuses on constructing a general expression for the derivative of the energy (with respect to a domain), and on deriving the corresponding evolution speed. More precisely, we first show by an example that the estimator of the distribution parameters is crucial for the derived speed expression. On the one hand, when using the maximum likelihood (ML) estimator for these parameters, the evolution speed has a closed-form expression that depends simply on the probability density function. On the other hand, complicating additive terms appear when using other estimators, e.g. method of moments. We then proceed by stating a general result within the framework of multi-parameter exponential family. This result is specialized to the case of the anti-log-likelihood function with the ML estimator and to the case of the relative entropy. Experimental results on simulated data confirm our expectations that using the appropriate noise model leads to the best segmentation performance. We also report preliminary experiments on real life Synthetic Aperture Radar (SAR) images to demonstrate the potential applicability of our approach.  相似文献   
8.
This paper presents an innovating real time method for detecting road obstacles by on board stereovision. After having exposed the stakes of the obstacles detection, having presented the state of the art and having identified the problems to be solved, the developed approach is described. It is based on the analysis of the “v-disparity” image, which provides a suitable representation of the geometric content of the road scene. The method is then evaluated with respect to the problems generally affecting stereovision approaches. The theoretical good properties of the “v-disparity” algorithm — genericity, effectiveness, robustness, and computational efficiency — are thus experimentally confirmed. Thanks to the performances obtained, the described algorithm is used for on board driving assistance applications.  相似文献   
9.
The quantitative distribution of volatile compounds in the skin, top mesocarp, middle mesocarp, bottom mesocarp, inner mesocarp, and outer mesocarp of a white-fleshed peach (cv. Maura) was investigated. Volatile compounds were extracted by liquid–liquid microextraction (LLME) and analyzed by GC–FID and GC–MS. The results showed that the levels of volatiles in skin were significantly higher than those observed in the other parts of the fruit, whereas top and bottom mesocarp were mainly discriminated by opposite concentrations in unsaturated lactones and C6-compounds. Distribution of lactones was also found to be different in skin and pulp according to their carbon chain length. Finally, the highest concentrations of benzaldehyde were found to be mainly located close to the stone suggesting that in peach this compound could be derived from enzymatic hydrolysis of amygdalin.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号