全文获取类型
收费全文 | 1006篇 |
免费 | 55篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 1064篇 |
出版年
2023年 | 9篇 |
2022年 | 10篇 |
2021年 | 30篇 |
2020年 | 22篇 |
2019年 | 15篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 27篇 |
2015年 | 26篇 |
2014年 | 32篇 |
2013年 | 63篇 |
2012年 | 61篇 |
2011年 | 53篇 |
2010年 | 53篇 |
2009年 | 53篇 |
2008年 | 52篇 |
2007年 | 53篇 |
2006年 | 45篇 |
2005年 | 34篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 37篇 |
2000年 | 30篇 |
1999年 | 27篇 |
1998年 | 51篇 |
1997年 | 37篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有1064条查询结果,搜索用时 187 毫秒
91.
Tae Chang Park Tae Young Kim Yeong Koo Yeo 《Korean Journal of Chemical Engineering》2010,27(6):1662-1668
In polyolefin processes the melt flow index (MFI) is the most important control variable indicating product quality. Because
of the difficulty in the on-line measurement of MFI, a large number of MFI estimation and correlation methods have been proposed.
In this work, mechanical predicting methods such as partial least squares (PLS) method and support vector regression (SVR)
method are employed in contrast to conventional dynamic prediction schemes. Results of predictions are compared with other
prediction results obtained from various dynamic prediction schemes to evaluate predicting performance. Hourly MFIs are predicted
and compared with operation data for the high density polyethylene process involving frequent grade changes. We can see that
PLS and SVR exhibit excellent predicting performance even for severe operating situations accompanying frequent grade changes. 相似文献
92.
In current Peer-to-Peer streaming applications, a lot of research attempts to provide timely stream services to the end users.
Most of them focus on how to organize the peer connections into an efficient overlay network. Due to the variation in the
network, a lot of overhead is generated when the overlay structure adapts to the changes. In order to minimize the impact
of network fluctuation, we proposed a scheduling algorithm which helps to distribute stream data efficiently through the fluctuating
networks. It needs only partial information about overlay structure and provides the services to satisfy most number of users.
The global latency experienced by peers in the system is thus minimized. To alleviate the problem of packet loss along the
overlay, we introduce retransmission requests into our scheduling algorithm. Requests for much needed data are treated with
higher priority. Parent peers which receive the request will re-send the missing data to minimize the loss impact. The missing
data which are needed by more peers will have a larger cumulative impact through the tree overlay and these are thus scheduled
and sent earlier. Simulation results showed that our prioritization and scheduling algorithm minimizes the negative impact
of fluctuation and data loss in a dynamic network environment. 相似文献
93.
Gin-Nae Ahn Kil-Nam Kim Seon-Heui Cha Choon-Bok Song Jehee Lee Moon-Soo Heo In-Kyu Yeo Nam-Ho Lee Young-Heun Jee Jin-Soo Kim Min-Soo Heu You-Jin Jeon 《European Food Research and Technology》2007,226(1-2):71-79
The potential antioxidant activities of three phlorotannins (phloroglucinol, eckol and dieckol) purified from Ecklonia cava collected in Jeju Island were investigated to evaluate their potential value as the natural products for foods or cosmetic
application. In this study, antioxidant activities were measured by electron spin resonance spectrometry (ESR) technique for
scavenging effects of free radicals such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), alkyl, hydroxyl (HO•) and superoxide anion radical (O2
•−) and by comet assay for protecting effects against H2O2-mediated DNA damage. The results show that all the phlorotannins have the potential DPPH, alkyl, hydroxyl and superoxide
radical scavenging activities. Especially, eckol samples scavenged around 93% of DPPH at 0.25, 0.5, 1 mg/mL of concentrations
and were higher than the other phlorotannins, such as phloroglucinol and dieckol samples. Also, protecting effects of the
phlorotannins against H2O2-mediated DNA damage increased with increased concentrations of the samples in the L5178 mouse T-cell lymphoma cell lines
(L5178Y-R). In conclusion, these results suggest that the three phlorotannins purified from E. cava have the potential inhibitory effect on H2O2-mediated DNA damage and harmful free radicals and can be used as antioxidants in cosmetic, foods and drug industry. 相似文献
94.
Young-Sik Jeong Won-Hee Han Eun-Ha Song Sang-Soo Yeo 《Simulation Modelling Practice and Theory》2010,18(4):416-430
In this paper, we designed and implemented the active emergency call system for emergency call service actively. Active emergency call system has two physical components; E-Device (Emergency Mobile Device) and E-Server (Emergency Server). The role of E-Device is the mobile device in order to call emergency by using mild handicapped, the elderly and children who are able to communicate their intention to another. E-Server is the server for management E-Devices with realtime monitoring. E-Device will be developed to the portable size for easily mild handicapped, the elderly and children. When they need the service of emergency call, the button of E-Device can be used and the call signal is transmitted to the emergency office and the guardian through Internet and CDMA. E-Server should be developed the integrated control system for management of E-Devices basically. And it also supported to realtime monitoring of E-Devices with respect to high quality of emergency call service for rise the efficiency. And finally we describe the results of performance evaluation about the location error of E-Device between coordinate of GPS received signal and actual E-Device coordinate, when it has been called emergency, by using DEVS (Discrete Event System Specification) formalism. 相似文献
95.
Securing routing layer functions in mobile ad hoc networks is an important issue, which includes many challenges like how to enhance detection accuracy when facing the highly dynamic characteristic of such networks, and how to distinguish malicious accusations under a totally autonomous structure. In this paper, we propose Distributed Court System (DCS), a complete Intrusion Detection System that intends to solve these challenges in a low-cost and robust way. We do not deploy any centralized entity, but rely on the collaboration among the nodes neighbouring the suspected node, to integrate information, improve the detection accuracy, and reject dissemination of malicious accusation. Through mathematical analysis and simulation, the proposed DCS is proved to be effective in a highly mobile and hostile network environment. 相似文献
96.
Packaged wheat flour stored in direct contact with chlordane-treated shelf paper adsorbed with time appreciable amounts of the pesticide from the paper. Direct contact of the package with the paper was more conducive to flour contamination than it was from exposure of the flour to the vaporized pesticide components from the paper. Sorption effects of the pesticide with flour varied with the mode of exposure and the type of bag used, i.e. when the bags were in direct contact with the shelf paper, the flour packaged in polyethylene bags contained the largest amount of chlordane residue (29 ppm), which decreased about 10 per cent when packaged in single-thickness kraft paper bags and about 35 per cent in double-thickness kraft paper bags. When the bags were separated from direct contact with the shelf paper by means of open glass containers, contamination of the flour was tangibly decreased, whereby the amounts of residue found in the kraft single- and double-thickness paper bags were 0·4 and 0·3 ppm, respectively, compared to only 0·06 ppm in the polyethylene bags. 相似文献
97.
98.
Using a high-resolution, high-dynamic bandwidth capacitive force transducer and two piezoelectric actuators, adhesive pull-off forces between nominally flat rough silicon surfaces were measured under various dynamic conditions in normal and tangential directions and environmental humidity levels. The upper specimen approached and retracted with a constant velocity in the vertical (normal) direction, while the lower specimen started moving in the horizontal (tangential) direction during the middle of the contact. The experiments were performed under 35 and 60% relative humidity conditions. It was found that sliding of the contacting surfaces led to a significant reduction in pull-off forces under low-humidity contact conditions, whereas it caused higher pull-off forces under partially wet contact conditions. Comparing the effects of sliding velocity and sliding distance on the measured pull-off force values, it was found that the sliding distance played an important role in the increase in pull-off forces. 相似文献
99.
100.
P. Yeo R. Arès S. P. Watkins G. A. Horley P. O’Brien A. C. Jones 《Journal of Electronic Materials》1997,26(10):1174-1177
We report the use of a new precursor, trisneopentylgallium (NPG) for the growth of GaAs by atomic layer epitaxy (ALE). In
contrast to most other alkyl gallium precursors such as triethylgallium, which decompose via a β-hydride elimination mechanism,
this compound undergoes homolysis similar to that of trimethylgallium (TMGa), the normal choice as an ALE precursor. Clear
self-limiting growth behavior similar to that of TMGa was observed over a reasonably wide range of growth conditions (430–500°C).
Carbon incorporation was not significantly reduced compared with TMGa suggesting that the adsorbed neopentyl radicals undergo
decomposition to result in a methyl terminated surface identical to that obtained for growth with TMGa. 相似文献