全文获取类型
收费全文 | 324篇 |
免费 | 9篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 57篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 11篇 |
能源动力 | 5篇 |
轻工业 | 28篇 |
水利工程 | 4篇 |
无线电 | 20篇 |
一般工业技术 | 40篇 |
冶金工业 | 76篇 |
自动化技术 | 84篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 11篇 |
2012年 | 20篇 |
2011年 | 22篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 19篇 |
2007年 | 9篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1974年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1951年 | 2篇 |
1950年 | 1篇 |
1949年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 15 毫秒
61.
Light Leah L.; LaVoie Donna; Valencia-Laver Debra; Albertson Owens Shirley A.; Mead Gale 《Canadian Metallurgical Quarterly》1992,18(6):1284
In 2 experiments, young and older adults demonstrated modality effects of similar magnitude in perceptual identification tasks. That is, both young and older adults demonstrated more repetition priming when study and test modalities matched than when they were different, suggesting that contextual information was equally available across age. However, when asked explicitly to retrieve modality information, older adults were less accurate than young adults. These results constitute evidence for a dissociation between direct and indirect measures of memory for modality information. They call into question hypotheses that memory impairment in old age is due to deficient encoding of contextual information and challenge current accounts of modality effects in repetition priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
62.
Friedman Leah; Brooks John O.; Bliwise Donald L.; Yesavage Jerome A.; Wicks Deryl S. 《Canadian Metallurgical Quarterly》1995,10(3):352
This study compared the level of self-reported stress of 42 older good sleepers (M age?=?68.2 years) and 42 poor sleepers (M age?=?68.7 years). The relations among subjective ratings of sleep, level of perceived stress, and negative mood were analyzed for each group. Good and poor sleepers reported similar amounts of life stress, but the relations between life stress and sleep perceptions differed for the 2 groups. Specifically, within the group of poor sleepers, those with higher life stress had greater difficulty falling asleep and less early morning waking than did poor sleepers with lower life stress. There was no association between life stress and any sleep measures for good sleepers. These results are compatible with the notion that good and poor sleepers may have different susceptibilities to poor sleep despite experiencing similar stressful life events. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
Zelinski Elizabeth M.; Light Leah L.; Gilewski Michael J. 《Canadian Metallurgical Quarterly》1984,20(6):1181
The hypothesis that older adults remember prose less well than young adults because they are less sensitive to the structure of prose passages was investigated in three experiments. In Experiments 1 and 2, older adults (aged 54–85) recalled less information than younger ones (aged 20–36) from stories having various structures, but there was no evidence that older people were insensitive to story structure. The pattern of recall of information high and low in the story structure was similar for young and old for each story examined. Experiment 3 extended the findings to recall of full-length essays and their summaries. These results suggest that the old are as sensitive to passage structure as the young. In addition, comparisons across the three experiments suggest that other frequently invoked explanations of age deficits in prose recall, such as individual differences in verbal ability and the nature of the materials used, cannot explain our results. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
This study examined the contributions of physical and sensorimotor development to manipulation in capuchins (Cebus apella) from birth to 2 years. Between months 1–6 and 7–12, manipulation increased significantly in frequency, in the proportion that was vigorous or required fine motor control, and in the proportion directed at portable objects. Fine motor control, moving objects in relation to the body, and stamina are largely in place by 12 months, after which little changed. All elements of the manipulative repertoire have appeared, and vigorous and dexterous activities have peaked before fully independent foraging. Emergence of permanent dentition and achievement of approximately half of adult body size accompany the attainment of fully independent foraging at 15 months. Thereafter, increasing strength and specific knowledge probably contribute more to changing foraging competence in young capuchins than do stamina and sensorimotor development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
Rmi Loire Herv Pigay Jean‐Ren Malavoi Leah Beche Quentin Dumoutier Julie Mosseri Caroline Kerjean 《河流研究与利用》2019,35(8):1107-1118
Large‐scale flow release experiments are becoming common for improving aquatic habitat quality downstream of dams. Because of the naturally high fine sediment load in the Durance River, France due to inputs from torrential tributaries draining badlands, unpredictable high flow events with dam overspill are not always sufficient to prevent clogging, which can lead to habitat degradation (especially spawning habitats) in bypassed reaches. Therefore, large‐scale flow experiments were conducted on four reaches to test the efficacy of clear‐water releases to improve aquatic habitat conditions. Continuous measurements of water depth, suspended sediment concentrations, and turbidity were conducted during twelve releases and compared on nine. Before and after each release, superficial clogging was measured. The study shows that there is a link between the volume of suspended sediments carried by water releases and the initial clogging. The volumes carried were low compared with the river's annual transport. The effect on clogging can vary significantly from one release to another. In particular, the hydrological context surrounding the releases has a significant influence on clogging. Comparisons of monitoring showed that releases are more effective on reaches that are more severely regulated (high hydrological control) than on those that are less well‐controlled. The areas with the highest initial clogging tend to unclog more than those with lower initial clogging; however, the latter zones are most impacted by ineffective releases. Performing a release on environments with low initial clogging can therefore be environmentally damaging. To ensure that releases are successful and that intervention is warranted, initial clogging should be measured in the field and releases should only be performed if the clogging is judged to be unfavourable. 相似文献
66.
Ensuring that service-oriented systems can adapt quickly and effectively to changes in service quality, business needs and their runtime environment is an increasingly important research problem. However, while considerable research has focused on developing runtime adaptation frameworks for service-oriented systems, there has been little work on assessing how effective the adaptations are. Effective adaptation ensures the system remains relevant in a changing environment and is an accurate reflection of user expectations. One way to address the problem is through validation. Validation allows us to assess how well a recommended adaptation addresses the concerns for which the system is reconfigured and provides us with insights into the nature of problems for which different adaptations are suited. However, the dynamic nature of runtime adaptation and the changeable contexts in which service-oriented systems operate make it difficult to specify appropriate validation mechanisms in advance. This paper describes a novel consumer-centered approach that uses machine learning to continuously validate and refine runtime adaptation in service-oriented systems, through model-based clustering and deep learning. 相似文献
67.
We revisit the classic problem of preemptive scheduling on m uniformly related machines. In this problem, jobs can be arbitrarily split into parts, under the constraint that every job is processed completely, and that the parts of a job are not assigned to run in parallel on different machines. We study a new objective which is motivated by fairness, where the goal is to minimize the sum of the two maximal job completion times. We design a polynomial time algorithm for computing an optimal solution. The algorithm can act on any set of machine speeds and any set of input jobs. The algorithm has several cases, many of which are very different from algorithms for makespan minimization (algorithms that minimize the maximum completion time of any job), and from algorithms that minimize the total completion time of all jobs. 相似文献
68.
Leah Castillon Berardi Vernon L. Frampton 《Journal of the American Oil Chemists' Society》1957,34(8):399-401
- The crude oils studied contained from 0.00 to 0.04% gossypol.
- Much of the gossypol added to crude cottonseed oils disappeared in one hour.
- The disappearance of gossypol from refined, bleached, and deodorized cottonseed oil, from highly purified tripelargonin, and from ethyl acetate is demonstrable after the lapse of one hour.
- It is suggested that the initial reaction of gossypol in the oils is an ester exchange reaction.
- It is further suggested that secondary reactions result in the production of a red coloration product that is not removable from the oil by the standard refining and bleaching methods.
69.
Walter A. Pons Jr. Mildred D. Murray Marion F. H. LeBlanc Jr. Leah E. Castillon 《Journal of the American Oil Chemists' Society》1953,30(3):128-132
Summary The processing of cottonseed by five commercial mills has been systematically examined with reference to free gossypol reduction,
nitrogen solubility, thiamine reduction, material balances of total gossypol, and the distribution of gossypol in processing.
One hydraulic mill reduced the free gossypol in the meal to a low level, approximating the level obtained in screw pressing.
For a given mill the free gossypol contents of the meals were found to be fairly uniform.
Low free gossypol content of hydraulic-pressed meals depends on the thoroughness with which the gossypol is bound in the cooking.
Gossypol is bound in both the cooking and pressing in the production of screw-pressed meals.
A relatively small amount of total gossypol is lost or destroyed in processing cottonseed by either hydraulic- or screw-pressing
methods. This small loss occurs while the meats are being prepared for pressing. No significant loss was found which could
be attributed to the pressing operations.
Serew-pressed oils appear to contain several times as much gossypol as hydraulic-pressed oils, with the amount dependent on
the extent of the binding of gossypol in the cooking and mechanical preparation of the meats for pressing.
The high temperatures developed in screw pressing contributed to a higher reduction in thiamine and nitrogen solubility than
was observed for hydraulic pressing.
One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S.
Department of Agriculture. 相似文献
70.
Jacobs K Foley G Punnett L Hall V Gore R Brownson E Ansong E Markowitz J McKinnon M Steinberg S Ing A Wuest E Dibiccari L 《Ergonomics》2011,54(2):206-219
The objective of this pilot study was to identify if notebook accessories (ergonomic chair, desktop monitor and notebook riser) combined with a wireless keyboard, mouse and participatory ergonomics training would have the greatest impact on reducing self-reported upper extremity musculoskeletal discomfort in university students. In addition to pre-post computing and health surveys, the Ecological Momentary Assessment was used to capture change in discomfort over time using a personal digital assistant (PDA) as the e-diary. The PDA was programmed with a survey containing 45 questions. Four groups of university students were randomised to either intervention (three external computer accessories) or to control. Participants reported less discomfort with the ergonomic chair and notebook riser based on the pre-post survey data and the e-diary/PDA ANOVA analysis. However, the PDA data, adjusted for the effect of hours per day of computer use, showed no benefit of the chair and limited benefit from the riser. Statement of Relevance:University students' use of notebook computers has increased. This study found evidence of a positive effect of an adjustable chair or notebook riser when combined with ergonomic training on reducing discomfort. Daily notebook computer use of 4?h was confirmed as a risk factor. Without some form of ergonomic intervention, these students are likely to enter the workforce with poor computing habits, which places them on the road to future injuries as technology continues to play a dominant role in their lives. 相似文献