全文获取类型
收费全文 | 1514篇 |
免费 | 69篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 22篇 |
化学工业 | 410篇 |
金属工艺 | 30篇 |
机械仪表 | 24篇 |
建筑科学 | 58篇 |
矿业工程 | 4篇 |
能源动力 | 41篇 |
轻工业 | 147篇 |
水利工程 | 9篇 |
石油天然气 | 1篇 |
无线电 | 126篇 |
一般工业技术 | 316篇 |
冶金工业 | 120篇 |
原子能技术 | 12篇 |
自动化技术 | 270篇 |
出版年
2023年 | 12篇 |
2022年 | 18篇 |
2021年 | 25篇 |
2020年 | 27篇 |
2019年 | 24篇 |
2018年 | 33篇 |
2017年 | 41篇 |
2016年 | 48篇 |
2015年 | 37篇 |
2014年 | 65篇 |
2013年 | 101篇 |
2012年 | 91篇 |
2011年 | 87篇 |
2010年 | 85篇 |
2009年 | 86篇 |
2008年 | 96篇 |
2007年 | 67篇 |
2006年 | 51篇 |
2005年 | 63篇 |
2004年 | 59篇 |
2003年 | 51篇 |
2002年 | 48篇 |
2001年 | 18篇 |
2000年 | 24篇 |
1999年 | 21篇 |
1998年 | 46篇 |
1997年 | 22篇 |
1996年 | 22篇 |
1995年 | 17篇 |
1994年 | 22篇 |
1993年 | 22篇 |
1992年 | 11篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1968年 | 3篇 |
排序方式: 共有1590条查询结果,搜索用时 15 毫秒
81.
Yves Roisin C. Everaerts J. M. Pasteels O. Bonnard 《Journal of chemical ecology》1990,16(10):2865-2875
The soldier frontal gland secretion ofNasutitermes princeps induces strong short-range caste-specific alarm and attraction in both soldiers and workers. Soldiers are excited and patrol the surroundings of the source. The secretion per se does not induce ejection of additional secretion. Large workers of the second stage or older are massively attracted when tested in homogeneous groups. They focus their activities much more accurately than the soldiers around the source. The workers' reaction is less intense in the presence of soldiers. Large and small workers of stage 1 scarcely react at all to the secretion, whether tested in homogeneous or mixed groups. These results suggest the following complementary roles of soldiers and workers in defense. The first line of defense is provided by soldiers, which immobilize and incapacitate mobile enemies with their sticky secretion. Defense then is completed by older large workers as they eliminate the source of disturbance. The absence of reaction of young workers, small or large, confirms previous reports on age polyethism inNasutitermes observed in other contexts: young workers tend to stay in the nest. Alarm reactions are elicited by a source of (+)--pinene, the major monoterpene in the secretion, while its enantiomer, almost absent from the secretion, induces a much weaker reaction. 相似文献
82.
Antoine Le Mortellec Joffrey Clarhaut Yves Sallez Thierry Berger Damien Trentesaux 《Engineering Applications of Artificial Intelligence》2013,26(1):227-240
The use of electronic equipment and embedded computing technologies in modern complex transportation systems continues to grow in a highly competitive market, in which product maintainability and availability is vital. These technological advances also make fault diagnosis and maintenance interventions much more challenging, since these operations require a deep understanding of the entire system. This paper proposes a holonic cooperative fault diagnosis approach, along with a generic architecture, to increase the embedded diagnosis capabilities of complex transportation systems. This concept is applied to the fault diagnosis of door systems of a railway transportation system. 相似文献
83.
Yves Denizot Laurence Michel Jacques Benveniste Alain Meybeck Yolène Thomas Louis Duberfret 《Lipids》1991,26(12):1093-1094
Paf is a phospholipid mediator present in human skin which induces inflammatory events such as neutrophil infiltration and
increased vascular permeability. Recent data suggest that cutaneous cells, such as fibroblasts and keratinocytes, produce
paf and that paf is released during allergic cutaneous reactions. It is tempting to speculate that paf may contribute to the
development of various skin disorders with acute and chronic skin inflammation. Paf antagonists may help in bringing answers
to this hypothesis and may offer new prospects for the treatment of cutaneous inflammatory diseases.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. 相似文献
84.
Anne Benoit Yves Robert Arnold L. Rosenberg Frédéric Vivien 《Theory of Computing Systems》2013,53(3):386-423
One has a large workload that is “divisible”—its constituent work’s granularity can be adjusted arbitrarily—and one has access to p remote worker computers that can assist in computing the workload. How can one best utilize the workers? Complicating this question is the fact that each worker is subject to interruptions (of known likelihood) that kill all work in progress on it. One wishes to orchestrate sharing the workload with the workers in a way that maximizes the expected amount of work completed. Strategies are presented for achieving this goal, by balancing the desire to checkpoint often—thereby decreasing the amount of vulnerable work at any point—vs. the desire to avoid the context-switching required to checkpoint. Schedules must also temper the desire to replicate work, because such replication diminishes the effective remote workforce. The current study demonstrates the accessibility of strategies that provably maximize the expected amount of work when there is only one worker (the case p=1) and, at least in an asymptotic sense, when there are two workers (the case p=2); but the study strongly suggests the intractability of exact maximization for p≥2 computers, as work replication on multiple workers joins checkpointing as a vehicle for decreasing the impact of work-killing interruptions. We respond to that challenge by developing efficient heuristics that employ both checkpointing and work replication as mechanisms for decreasing the impact of work-killing interruptions. The quality of these heuristics, in expected amount of work completed, is assessed through exhaustive simulations that use both idealized models and actual trace data. 相似文献
85.
Muhammad Kaleem Yves Farizon Francis Enjalbert Annabelle Troegeler‐Meynadier 《European Journal of Lipid Science and Technology》2013,115(2):161-169
Heating oilseeds has been shown to improve the milk fatty acid profile when given to dairy cows, compared to raw oilseeds. However, results from published studies are conflicting. The conditions of heating and storage of the oilseeds could be responsible for these differences, probably partly through their effects on lipid oxidation, the products of which could act on ruminal biohydrogenation (BH). Thus, 15 different treatments were applied to ground soybeans: three levels of heating (no heating, 30 min at 110 or 150°C) × 5 ambient storage durations (0, 1, 2, 4, or 6 months). Soybeans were incubated in vitro with ruminal fluid for 6 h. Triacylglycerol (TAG) polymers, hydroperoxides and hydroxyacids (HOA), aldehydes, and fatty acids were assayed in soybeans and ruminal culture. No TAG polymer was detected in any treatment. Soybeans stored for a long time had a high content of HOA, whereas those heated at 150°C, whatever the storage duration, had high aldehyde contents. The percentage disappearance of cis‐9,cis‐12 18:2 and cis‐9,cis‐12,cis‐15 18:3 in incubates decreased significantly in cultures with heated soybeans, especially at 150°C, suggesting that this partial protection of polyunsaturated fatty acids (PUFA) from BH was at least in part linked to the aldehyde content of the heated soybeans. Practical applications: Oilseeds given to ruminants are often heated, and heat treatment is known to generate oxidation products. Knowing what oxidation products influence ruminal biohydrogenation of unsaturated fatty acids could result in technological processes allowing a better transfer of unsaturated fatty acids from oilseeds to ruminant products. 相似文献
86.
Object
Dynamic contrast enhanced MRI and pharmacokinetic modelling provide a powerful tool for tumour diagnosis and treatment evaluation. However, several studies show low reproducibility of the technique and poor precision of the transendothelial transfer constant K trans. This work proposes a theoretical framework describing how finite signal-noise-ratio (SNR) in the MR images is propagated throughout the measurement protocol to uncertainty on the kinetic parameter estimates. 相似文献87.
In recent years, statistical machine translation has gained much attention. The phrase‐based statistical machine translation model has made significant advancement in translation quality over the word‐based model. In this paper, we attempt to apply the technique of proportional analogy to statistical machine translation systems. We propose a novel approach to apply proportional analogy to generate translations of unseen n‐grams from the phrase table for phrase‐based statistical machine translation. Experiments are conducted with two datasets of different sizes. We also investigate two methods to integrate n‐grams translations produced by proportional analogy into the state‐of‐the‐art statistical machine translation system, Moses.1 The experimental results show that unseen n‐grams translations generated using the technique of proportional analogy are rewarding for statistical machine translation systems with small datasets. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
88.
89.
90.
High niobium oxide content in germanate glasses: Thermal,structural, and optical properties 下载免费PDF全文
Lia Mara Marcondes Sérgio Maestri Bianca Sousa Rogeria Rocha Gonçalves Fabia Castro Cassanjes Gael Yves Poirier 《Journal of the American Ceramic Society》2018,101(1):220-230
Niobium alkali germanate glasses were synthesized by the melt‐quenching technique. The ternary system (90‐x)GeO2–xNb2O5–10K2O forms homogeneous glasses with x ranging from 0 to 20 mol%. Samples were investigated by DSC and XRD analysis, FTIR and Raman spectroscopy, and optical absorption. Structural and physical features are discussed in terms of Nb2O5 content. The niobium content increase in the glass network strongly modifies the thermal, structural and optical properties of alkali germanate glasses. DSC, Raman and FTIR analysis suggest niobium addition promotes NbO6 groups insertion close to GeO4 units of the glass network. XRD analysis also pointed out that samples containing high niobium oxide contents exhibit preferential niobium oxide‐rich phase after crystallization after heat treatment, which is similar to orthorhombic Nb2O5. Absorption spectra revealed high transmission range between 400 nm to 6.2 μm, added to a considerably decreased hydroxyl group content as the addition of niobium in the alkali germanate network. The niobium oxide‐rich phase crystallization process was studied and activation energy was determined, as well as nucleation and crystal growth temperatures and time for obtaining transparent glass‐ceramics. 相似文献