全文获取类型
收费全文 | 370篇 |
免费 | 8篇 |
专业分类
电工技术 | 9篇 |
综合类 | 1篇 |
化学工业 | 34篇 |
金属工艺 | 1篇 |
机械仪表 | 9篇 |
建筑科学 | 16篇 |
能源动力 | 39篇 |
轻工业 | 26篇 |
石油天然气 | 2篇 |
无线电 | 16篇 |
一般工业技术 | 44篇 |
冶金工业 | 113篇 |
原子能技术 | 1篇 |
自动化技术 | 67篇 |
出版年
2024年 | 3篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 19篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 32篇 |
1997年 | 19篇 |
1996年 | 21篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1963年 | 2篇 |
1946年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 15 毫秒
21.
22.
We conducted two studies to examine perceptions of, and reactions to, ostracism occurring either in-person or online. In study 1, participants read a vignette describing either in-person or online ostracism, then estimated their psychological and interpersonal responses as if they experienced such ostracism. Participants anticipated experiencing distress, and this was consistent across ostracism method. Ostracism method did predict negative affect (NA), with greater NA increases anticipated for in-person exclusion, compared to online. A significant interaction between gender and ostracism method predicted anticipated belonging. Males anticipated higher belonging in the in-person condition (relative to online); females anticipated more belonging in the online condition. In study 2, participants experienced in-person or online ostracism during a brief interaction with study confederates. Both conditions elicited similar reports of low inclusion, high exclusion, and significant decreases in positive and negative affect. Ostracism method qualified self-esteem (SE) results; chat room participants indicated an increase in SE following ostracism, whereas in-person participants reported a slight decrease. Males and females were similarly affected by both conditions. These studies demonstrate that online experiences of ostracism may be as meaningful as those experienced in person. Whether this finding generalizes to those with less technological familiarity should be examined further. 相似文献
23.
Many online stores encourage their users to submit product or service reviews in order to guide future purchasing decisions. These reviews are often listed alongside product recommendations but, to date, limited attention has been paid as to how best to present these reviews to the end-user. In this paper, we describe a supervised classification approach that is designed to identify and recommend the most helpful product reviews. Using the TripAdvisor service as a case study, we compare the performance of several classification techniques using a range of features derived from hotel reviews. We then describe how these classifiers can be used as the basis for a practical recommender that automatically suggests the most-helpful contrasting reviews to end-users. We present an empirical evaluation which shows that our approach achieves a statistically significant improvement over alternative review ranking schemes. 相似文献
24.
Harold R. Clark Robert P. Stawicki Imelda P. Smyth Eugene Potkay 《Journal of the American Ceramic Society》1990,73(10):2987-2991
To follow the development of particle morphology, silica soot is extracted from four axial positions in the flame of a torch used to manufacture optical fiber preforms by the vaporphase axial deposition method. The soot, collected by three extraction techniques, is analyzed by transmission electron microscopy and gas adsorption to identify which characteristics of the soot morphology are dependent on the sampling technique and which upon the position in the flame. Comparison is also made to other work in which silica soot was extracted from a nondiffusion flame. 相似文献
25.
Munkombwe Muchindu Omotayo Arotiba Aoife Morrin Malcolm R. Smyth Boitumelo Kgarebe Emmanuel I. Iwuoha 《Electrochimica acta》2010,55(14):4274-284
Aniline doped with polyvinyl sulphonate (PV-SO3−) was electropolymerised on screen printed carbon (SPCE) and glassy carbon (GCE) electrodes. Then nano-structured polystyrene (PSNP) latex beads functionalised with amine (PSNP-NH2) and sulphate (PSNP-OSO3−) were self-assembled on the modified SPCE and GCE. The resultant polyaniline nanocomposites (PANI|PSNP-NH2 or PANI|PSNP-OSO3−) were characterised by cyclic voltammetry (CV), UV-vis spectroscopy and scanning electron microscopy (SEM). Brown-Anson analysis of the multi-scan rate CV responses of the various PANI films gave surface concentrations of the order of 10−8 mol cm−2. UV-vis spectra of the PANI films dissolved in dimethyl sulphoxide showed typical strong absorbance maxima at 480 and 740 nm associated with benzenoid π-π* transition and quinoid excitons of polyaniline, respectively. The SEM images of the PANI nanocomposite films showed cauliflower-like structures that are <100 nm in diameter. When applied as electrochemical nitrite sensor, sensitivity values of 60, 40 and 30 μA/mM were obtained for electrode systems containing PANI|PSNP-NH2, PANI and PANI|PSNP-SO3−, respectively. The corresponding limits of detection of the sensors were 7.4, 9.2 and 38.2 μM NO2−. 相似文献
26.
Jovanovic V.M. Bull M.A. Smyth M.M. Jia Zong 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(7):1512-1519
In order to facilitate a unique georectification approach implemented for Multi-angle Imaging SpectroRadiometer (MISR) data, specific calibration datasets need to be derived during flight. In the case of the spaceborne MISR instrument, with its unique configuration of nine fixed pushbroom cameras, continuous and autonomous coregistration and geolocation of image data are required prior to the application of scientific retrieval algorithms. In-flight-generated calibration datasets are required to (a) assure accuracy, (b) reduce processing load, and (c) support autonomous aspects of the processing algorithm. This paper describes the in-flight geometric calibration approach with the focus on the first year of activities and the georectification performance achieved. 相似文献
27.
Let x denote a given nonempty string of length n = |x| . A proper substring u of x is a proper cover of x if and only if every position of x lies within an occurrence of u within x . This paper introduces an array γ = γ[1..n] called the cover array in which each element γ[i] , 1 ≤ i ≤ n , is the length of the longest proper cover of x[1..i] or zero if no such cover exists. In fact it turns out that γ describes all the covers of every prefix of x . Several interesting properties of γ are established, and a simple algorithm is presented that computes γ on-line in Θ(n) time using Θ(n) additional space. Thus the new algorithm computes for all prefixes of x information that previous cover algorithms could compute only for x itself, and does so with no increase in space or time complexity. 相似文献
28.
William L Warren Duane Dimos Bruce A. Tuttle Donald M. Smyth 《Journal of the American Ceramic Society》1994,77(10):2753-2757
We have coupled electron paramagnetic resonance (EPR) and polarization–voltage measurements to understand the effects of reducing ambients on the remanent polarization and density of paramagnetic centers in BaTiO3 , single crystals. Two types of reducing ambients were explored; one was done under vacuum (slightly reducing) and the second was performed in forming gas (very reducing). It is found that the vacuum anneal caused a reduction in the remanent polarization and a concomitant decrease in the isolated Fe3+ EPR resonance. The Fe3+ –Vo complex EPR signal was relatively unaffected by this vacuum anneal. By injecting charge using an ultraviolet (UV) light and an applied bias combination, the polarization and the isolated Fe3+ signal intensity were restored, thereby suggesting that the suppression of the remanent polarization is due to trapping of electronic charge at the domain walls. For the forming gas anneal, we observe a much larger decrease in remanent polarization with an accompanying decrease in both the isolated Fe3+ and Fe3+ –Vo complex EPR signals. For this anneal, charge injection by the UV light/bias combination did not restore the polarization nor the EPR densities. The remanent polarization, the isolated Fe3+ , and the Fe3+ –Vo Vo complex could be restored only by a reoxidizing anneal, suggesting that ionic defects {oxygen vacancies) are now responsible for pinning the domain walls. Collectively, these results suggest reducing anneals can suppress the amount of switchable polarization in BaTiO3 by either electronic or ionic trapping mechanisms. 相似文献
29.
Update rates and fidelity in virtual environments 总被引:1,自引:0,他引:1
Interaction is the primary characteristic of a Virtual Environment and update rate is normally taken as an index or measure of the interactivity of the system. The speed of many systems is dictated by the slowest component which is often the Computer Image Generator (CIG). It is common for the workload of the CIG to vary and hence the performance of the system. This paper shows how a variable update rate can produce undesirable results. Two solutions to this problem are presented: service degradation and worst-case. In the case of the CIG, service degradation would require the quality of the image to be reduced such that the time taken never exceeds a given deadline. The worst-case technique works by finding the longest time taken to render any view and then uses that as the deadline for completion. The support of predictive methods is one of several benefits of this approach. An implementation of the worst-case technique is described which takes finer control over the CIG than usual and may be applied to many existing systems with little modification. 相似文献
30.
CI Coiré E Horvath K Kovacs HS Smyth H Sasano K Iino DS Feig 《Canadian Metallurgical Quarterly》1998,42(3):650-654
Recently, perfusion imaging has been of increasing interest in MRI. We applied this method for semiquantitative evaluation of hepatic parenchymal portal blood flow in patients with diffuse liver damage. Twenty patients with diffuse hepatic damage were divided according to the Child's Classification and studied. Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was administered into the superior mesenteric artery (SMA), and a dynamic series of T2*-weighted fast low angle shot (FLASH) images was obtained. We evaluated relative regional portal blood volume (rrPBV), mean transit time (MTT), and relative regional portal blood flow (rrPBF). The relationship between the rrPBV, rrPBF, and plasma indocyanine green retention rate test at 15 minutes (ICGR15 was also evaluated in 12 patients. Both rrPBF and rrPBV are significantly decreased in Child B & C patients compared with Child A patients. On the other hand, the MTT is significantly prolonged in Child B & C patients compared with Child A patients. Significant correlations were also noted between rrPBV and ICGR15 and between rrPBF and ICGR15. By means of selective catheterization into the SMA, we were able to estimate rrPBV, rrPBF, and MTT. This method may play a clinical role for assessment of regional portal perfusion in various diseases with diffuse liver damage. 相似文献