首页 | 本学科首页   官方微博 | 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   44篇
  免费   0篇
化学工业   4篇
建筑科学   1篇
轻工业   6篇
水利工程   2篇
无线电   6篇
一般工业技术   2篇
冶金工业   22篇
自动化技术   1篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2015年   1篇
  2013年   1篇
  2009年   1篇
  2008年   2篇
  2005年   1篇
  2004年   2篇
  2000年   1篇
  1999年   6篇
  1998年   12篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1981年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有44条查询结果,搜索用时 625 毫秒
1.

Bursts of drinking water pipes not only cause loss of drinking water, but also damage below and above ground infrastructure. Short-term water demand forecasting is a valuable tool in burst detection, as deviations between the forecast and actual water demand may indicate a new burst. Many of burst detection methods struggle with false positives due to non-seasonal water consumption as a result of e.g. environmental, economic or demographic exogenous influences, such as weather, holidays, festivities or pandemics. Finding a robust alternative that reduces the false positive rate of burst detection and does not rely on data from exogenous processes is essential. We present such a burst detection method, based on Bayesian ridge regression and Random Sample Consensus. Our exogenous nowcasting method relies on signals of all nearby flow and pressure sensors in the distribution net with the aim to reduce the false positive rate. The method requires neither data of exogenous processes, nor extensive historical data, but only requires one week of historical data per flow/pressure sensor. The exogenous nowcasting method is compared with a common water demand forecasting method for burst detection and shows sufficiently higher Nash-Sutcliffe model efficiencies of 82.7% - 90.6% compared to 57.9% - 77.7%, respectively. These efficiency ranges indicate a more accurate water demand prediction, resulting in more precise burst detection.

  相似文献   
2.
Inhibition of hepatic cholesterol biosynthesis by chloroquine   总被引:1,自引:0,他引:1  
Chloroquine is shown to be a potent inhibitor of cholesterol biosynthesis by isolated rat hepatocytes. Half-maximal inhibition of cholesterogenesis occurs at ca. 10μM chloroquine. Chloroquine does not affect fatty acid synthesis by isolated hepatocytes. This suggests that chloroquine acts on the cholesterol biosynthetic pathway beyond the cytosolic acetyl-CoA branchpoint of cholesterol and fatty acid synthesis.  相似文献   
3.
In the context of future dynamic applications, systems will exhibit unpredictably varying platform resource requirements. To deal with this, they will not only need to be programmable in terms of instruction set processors, but also at least partial reconfigurability will be required. In this context, it is important for applications to optimally exploit the memory hierarchy under varying memory availability. This article presents a mapping strategy for wavelet-based applications: depending on the encountered conditions, it switches to different memory optimized instantations or localizations, permitting up to 51% energy gains in memory accesses. Systematic and parameterized mapping guidelines indicate which localization should be selected when, for varying algorithmic wavelet parameters. The results have been formalized and generalized to be applicable to more general wavelet-based applications.  相似文献   
4.
The objective was to measure the activities of all the enzymes essential for hepatic gluconeogenesis in dairy cows with induced fatty liver. We aimed to induce severe fatty liver in ten experimental cows by overfeeding them during the dry period while seven control cows were maintained on a restricted diet. To induce a marked negative energy balance, the experimental cows were deprived of feed for 8 h immediately after parturition. In addition, the experimental cows were given a restricted amount of diet during the first 5 d of lactation. Liver samples were collected 1 week before and 1, 2 and 4 weeks after parturition. Before parturition, liver triacylglycerol concentrations did not differ between the two groups. After parturition, the experimental cows developed marked fatty liver as indicated by a higher level of triacylglycerols in the liver compared with the control cows. Before parturition, all gluconeogenic enzymes in the liver were lower in experimental cows than in control cows. Phosphoenolpyruvate carboxykinase, pyruvate carboxylase and propionyl-CoA carboxylase were significantly lower and fructose 1,6-bisphosphatase and glucose 6-phosphatase tended to be lower in the experimental cows. The activities of two crucial enzymes for gluconeogenesis in ruminants, i.e., phosphoenolpyruvate carboxykinase and propionyl-CoA carboxylase, remained low throughout the sampling period post partum. Activities of pyruvate carboxylase and glucose 6-phosphatase in the experimental cows post partum were upgraded to values similar to those of the control cows. The results showed that the capacity for hepatic gluconeogenesis before parturition was lower in cows with induced fatty liver than in control cows. After parturition, the low activities of crucial gluconeogenic enzymes indicated insufficient production of glucose. It is suggested that the low gluconeogenic capacity leads successively to low blood glucose concentrations, low insulin levels and high rates of mobilization of fatty acid, causing severe hepatic lipidosis.  相似文献   
5.
We present a new method to extract scale-invariant features from an image by using a Cosine Modulated Gaussian (CM-Gaussian) filter. Its balanced scale-space atom with minimal spread in scale and space leads to an outstanding scale-invariant feature detection quality, albeit at reduced planar rotational invariance. Both sharp and distributed features like corners and blobs are reliably detected, irrespective of various image artifacts and camera parameter variations, except for planar rotation. The CM-Gaussian filters are approximated with the sum of exponentials as a single, fixed-length filter and equal approximation error over all scales, providing constant-time, low-cost image filtering implementations. The approximation error of the corresponding digital signal processing is below the noise threshold. It is scalable with the filter order, providing many quality-complexity trade-off working points. We validate the efficiency of the proposed feature detection algorithm on image registration applications over a wide range of testbench conditions.  相似文献   
6.
A fast-settling CMOS op amp for SC circuits with 90-dB DC gain   总被引:4,自引:0,他引:4  
A technique that combines the high-frequency behavior of a single-stage op amp with the high DC gain of a multistage design is presented. This technique is based on the concept that a very high DC gain can be achieved in combination with any unity-gain frequency achievable by a (folded-) cascode design. Bode-plot measurements for an op amp realized in a 1.6-μm process show a DC gain of 90 dB and a unity-gain frequency of 116 MHz (16-pF load). Settling measurements with a feedback factor of 1/3 show a fast single-pole settling behavior corresponding to a closed-loop bandwidth of 18 MHz (35-pF load) and a settling accuracy better than 0.03%. This technique does not cause any loss in output voltage swing. At a supply voltage of 5.0 V an output swing of about 4.2 V is achieved without loss in DC gain. The above advantages are achieved with a 30% increase in chip area and a 15% increase in power consumption  相似文献   
7.
BACKGROUND AND DESIGN: Primary cutaneous follicular center cell lymphomas represent a distinct type of cutaneous B-cell lymphoma, clinically characterized by localized skin lesions on the head or trunk and an excellent prognosis. Histologically similar lymphomas may occur on the legs. The clinical behavior of this group is still undefined, and controversy exists whether these lymphomas should be classified as follicular center cell lymphoma or B-immunoblastic lymphoma. We reviewed the clinical, histologic, and follow-up data of 18 patients with primary cutaneous large B-cell lymphoma of the legs. RESULTS: Primary cutaneous large B-cell lymphoma of the legs generally occurred in elderly patients (median age at diagnosis, 76 years), in particular women (male-female ratio, 7:2), and preferentially affected the lower legs (14 of 18 patients). Radiotherapy and/or systemic polychemotherapy resulted in complete remissions in 16 of 17 patients. Follow-up data demonstrated estimated 2- and 5-year survival rates of 77% and 58%, respectively. Histologic evaluation showed diffuse dermal infiltrates with variable proportions of centroblasts (large noncleaved cells), large centrocytes (large cleaved cells), and B immunoblasts. Seventeen of 18 patients were diagnosed as having primary cutaneous follicular center cell lymphoma; only 1 patient, whose histologic examination showed more than 30% immunoblasts, was diagnosed as having B-immunoblastic lymphoma. CONCLUSIONS: Primary cutaneous large B-cell lymphoma of the legs is a distinct clinicopathologic entity that mainly affects elderly patients and has an intermediate prognosis. Although most cases have a follicular center cell origin, primary cutaneous large B-cell lymphoma is proposed as the most appropriate term for this type of cutaneous lymphoma.  相似文献   
8.
Water Resources Management - The increasing age and deterioration of drinking water mains is causing an increasing frequency of pipe bursts. Not only are pipe repairs costly, bursts might also lead...  相似文献   
9.
10.
Poor air quality in schools has been associated with adverse health effects. Indoor air quality can be improved by increasing ventilation. The objective of this study was to compare the effectiveness of different interventions to improve ventilation behavior in primary schools. We used indoor CO(2) concentrations as an indicator. In 81 classes of 20 Dutch primary schools, we applied three different interventions: (i) a class-specific ventilation advice; (ii) the advice combined with a CO(2) warning device and (iii) the advice combined with a teaching package. The effectiveness of the interventions was tested directly after intervention and 6 weeks after intervention by measuring the CO(2) concentrations and comparison with a control group (iv). Before intervention, the CO(2) concentration exceeded 1000 ppm for 64% of the school day. The class-specific ventilation advice without further support appeared an ineffective tool to improve ventilation behavior. The advice in combination with a CO(2) warning device or the teaching package proved effective tools and resulted in lower indoor CO(2) concentrations when compared with the control group. Ventilation was significantly improved, but CO(2) concentrations still exceeded 1000 ppm for more than 40% of the school day. Hence, until ventilation facilities are upgraded, the CO(2) warning device and the teaching package are useful low-cost tools. PRACTICAL IMPLICATIONS: To improve ventilation behavior and indoor air quality in schools, CO(2) warning device and teaching package combined with a class-specific ventilation advice, are effective tools, while giving the ventilation advice solely, is not effective. Although ventilation is significantly improved through behavioral change, the ventilation rate is still insufficient to maintain good air quality during the full school day. Therefore, the improvement of the ventilation facilities is recommended. Hence, until ventilation facilities in schools are upgraded, the CO(2) warning device and the teaching package are useful low-cost tools to improve current indoor air quality.  相似文献   
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