全文获取类型
收费全文 | 1314篇 |
免费 | 33篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 170篇 |
金属工艺 | 12篇 |
机械仪表 | 13篇 |
建筑科学 | 100篇 |
矿业工程 | 5篇 |
能源动力 | 15篇 |
轻工业 | 133篇 |
水利工程 | 14篇 |
石油天然气 | 1篇 |
无线电 | 62篇 |
一般工业技术 | 123篇 |
冶金工业 | 500篇 |
原子能技术 | 4篇 |
自动化技术 | 187篇 |
出版年
2022年 | 15篇 |
2021年 | 12篇 |
2020年 | 21篇 |
2019年 | 23篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 55篇 |
2012年 | 36篇 |
2011年 | 59篇 |
2010年 | 34篇 |
2009年 | 45篇 |
2008年 | 58篇 |
2007年 | 40篇 |
2006年 | 42篇 |
2005年 | 43篇 |
2004年 | 40篇 |
2003年 | 28篇 |
2002年 | 32篇 |
2001年 | 35篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 55篇 |
1997年 | 51篇 |
1996年 | 45篇 |
1995年 | 21篇 |
1994年 | 40篇 |
1993年 | 25篇 |
1992年 | 29篇 |
1991年 | 12篇 |
1990年 | 25篇 |
1989年 | 26篇 |
1988年 | 18篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 9篇 |
1984年 | 17篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 8篇 |
1977年 | 10篇 |
1976年 | 21篇 |
1975年 | 11篇 |
1974年 | 12篇 |
1973年 | 8篇 |
1972年 | 9篇 |
排序方式: 共有1347条查询结果,搜索用时 15 毫秒
1.
Carolyn A. Grimley Stephen Funni Christopher Green Elizabeth C. Dickey 《Journal of the European Ceramic Society》2021,41(4):2807-2817
In flash sintering experiments, the thermal history of the sample is key to understanding the mechanisms underlying densification rate and final properties. By combining robust temperature measurements with current-ramp-rate control, this study examined the effects of the thermal profile on the flash sintering of yttria-stabilized zirconia, with experiments ranging from a few seconds to several hours. The final density was maximized at slower heating rates, although processes slower than a certain threshold led to grain growth. The amount of grain growth observed was comparable to a similar conventional thermal process. The bulk electrical conductivity correlated with the maximum temperature and cooling rate. The only property that exhibited behavior that could not be attributed to solely the thermal profile was the grain boundary conductivity, which was consistently higher than conventional in flash sintered samples. These results suggest that, during flash sintering, athermal electric field effects are relegated to the grain boundary. 相似文献
2.
Kosslyn Stephen M.; Koenig Olivier; Barrett Anna; Cave Carolyn Backer; Tang Joyce; Gabrieli John D. E. 《Canadian Metallurgical Quarterly》1989,15(4):723
Analyses of human object recognition abilities led to the hypothesis that 2 kinds of spatial relation representations are used in human vision. Evidence for the distinction between abstract categorical spatial relation representations and specific coordinate spatial relation representations was provided in 4 experiments. These results indicate that Ss make categorical judgments—on/off, left/right, and above/below—faster when stimuli are initially presented to the left cerebral hemisphere, whereas they make evaluations of distance—in relation to 2 mm, 3 mm, or 1 in. (2.54 cm)—faster when stimuli are initially presented to the right cerebral hemisphere. In addition, there was evidence that categorical representations developed with practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Learning to Perceive and Act by Trial and Error 总被引:5,自引:1,他引:4
This article considers adaptive control architectures that integrate active sensory-motor systems with decision systems based on reinforcement learning. One unavoidable consequence of active perception is that the agent's internal representation often confounds external world states. We call this phoenomenon perceptual aliasingand show that it destabilizes existing reinforcement learning algorithms with respect to the optimal decision policy. We then describe a new decision system that overcomes these difficulties for a restricted class of decision problems. The system incorporates a perceptual subcycle within the overall decision cycle and uses a modified learning algorithm to suppress the effects of perceptual aliasing. The result is a control architecture that learns not only how to solve a task but also where to focus its visual attention in order to collect necessary sensory information. 相似文献
4.
Digant Gupta Christopher G Lis Sadie L Dahlk Jessica King Pankaj G Vashi James F Grutsch Carolyn A Lammersfeld 《Nutrition journal》2008,7(1):19
Background
Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. 相似文献5.
LT Seery DR Schoenberg ME Canning AS Whitehead 《Canadian Metallurgical Quarterly》1994,150(2):331-333
LY171883, a peroxisome proliferator and leukotriene D4-antagonist, induced a statistically significant increase in the number of hepatic lesions in B6C3F1 female mice in a 2 year oncogenicity study at dietary doses of 0.0225% and 0.075%. The mutation frequency and spectrum of the 61st codon of H-ras was determined for 64 independent, archived lesions from the LY171883 2 year oncogenicity study using the polymerase chain reaction (PCR), allele specific oligo hybridization (ASO) and DNA sequencing. Results showed 41 (64%) of these lesions had mutations at the 61st codon (16/21 hepatocellular carcinomas, 4/10 hepatocellular adenomas, 19/26 focal hepatocellular hyperplasias and 2/7 focal hepatocellular atypia). These mutations consisted of 18 C-A transversions, 16 A-G transitions and seven A-T transversions. Compared to the mutation frequency for spontaneously occurring archival B6C3F1 hepatic lesions (41%), the frequency of LY171883 lesions (64%) was significantly higher (P < 0.01). The frequencies of H-ras 61st codon mutations among the LY171883 lesion types (hepatocellular carcinomas 76%, hepatocellular adenomas 40%, focal hepatocellular hyperplasias 73% and hepatocellular atypia 29%) were also significantly different (P = 0.035). In contrast, spontaneous lesions showed no statistical difference in the frequencies of mutation among lesion types (P > 0.5). The mutation spectrum of the LY171883 lesions was not significantly different from the spontaneous spectra. It may be concluded that based on the similarity in mutation spectrum and the increase in mutation frequency, LY171883 may selectively promote spontaneous hepatic lesions containing H-ras 61st codon mutations. In addition, the difference in mutation frequency among lesion types does not support a linear progression of all LY171883 lesions through focal atypia, focal hepatocellular hyperplasias, hepatocellular adenomas and hepatocellular carcinomas. 相似文献
6.
Carolyn McGregor Bruce Kneale Mark Tracy 《Journal of Network and Computer Applications》2007,30(4):1309-1323
Premature and ill term babies born in regional Australia must be moved to another hospital with Neonatal Intensive Care Unit (NICU) facilities. Transferred pre-term and critically ill term babies have higher mortality rates and much higher rates of long term disability than similar babies born in hospitals with NICU facilities. This paper details the Bush Babies Broadband project that aims to significantly improve the quality of treatment for babies born in rural, remote as well as urban areas by providing the first on-demand virtual NICU architecture in Australia. Real-time data collected from medical monitors and ventilators attached to the baby, audiovisual streams and static physiological data such as X-ray images are transmitted to the consulting Neonatologist to gain a better picture of the patient's condition than is currently available. The key contribution of this significant research is the infrastructure providing a mechanism for Neonatologists to receive information directly from a regional hospital, thereby preventing, in some cases, the immediate need to move the baby. A key benefit of this framework is that it is available to link regional hospitals with the supporting NICU Neonatologist ‘on demand’ eliminating the need to establish permanent point to point connections. This paper further describes the application of that architecture to a specific pilot connecting the Bathurst regional hospital with Neonatologists within the NICU at Nepean Hospital, Penrith Australia. 相似文献
7.
Yoon Carolyn; Feinberg Fred; Hu Ping; Gutchess Angela Hall; Hedden Trey; Chen Hiu-Ying Mary; Jing Qicheng; Cui Yao; Park Denise C. 《Canadian Metallurgical Quarterly》2004,19(3):379
Understanding how aging influences cognition across different cultures has been hindered by a lack of standardized, cross-referenced verbal stimuli. This study introduces a database of such item-level stimuli for both younger and older adults, in China and the United States, and makes 3 distinct contributions. First, the authors specify which item categories generalize across age and/or cultural groups, rigorously quantifying differences among them. Second, they introduce novel, powerful methods to measure between-group differences in freely generated ranked data, the rank-ordered logit model and Hellinger Affinity. Finally, a broad archive of tested, cross-linguistic stimuli is now freely available to researchers: data, similarity measures, and all stimulus materials for 105 categories and 4 culture-by-age groups, comprising over 10,000 fully translated unique item responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Bruce C. Bunker R. James Kirkpatrick Richard K. Brow Gary L. Turner Carolyn Nelson 《Journal of the American Ceramic Society》1991,74(6):1430-1438
9.
RP Whitehead J Jacobson TD Brown SA Taylor GR Weiss JS Macdonald 《Canadian Metallurgical Quarterly》1997,15(6):2414-2419
PURPOSE: Pancreatic cancer is difficult to treat, with most patients surgically unresectable at the time of diagnosis. Radiotherapy and chemotherapy can offer palliation, but more effective therapy is needed. This trial evaluated the effects of an aggressive schedule of paclitaxel given with granulocyte colony-stimulating factor (G-CSF) to patients with advanced pancreatic cancer. PATIENTS AND METHODS: All patients were required to have a histologic diagnosis of pancreatic adenocarcinoma with measurable disease and no prior chemotherapy or radiation therapy. Patients had to have performance status of 0 to 2, pretreatment absolute granulocyte count > or = 1,500/microL, and platelet count greater than or equal to the institutional lower limit of normal. Following pretreatment with dexamethasone, diphenhydramine, and cimetidine, patients received paclitaxel at a dose of 250 mg/m2 by 24-hour infusion on day 1, repeated every 21 days. G-CSF was given at a dose of 5 microg/kg/d on days 3 to 18 or until two consecutive absolute neutrophil counts (ANCs) > or = 10,000/microL were obtained. Doses of paclitaxel were modified depending on nadir counts. RESULTS: Forty-five patients were entered onto this study, with six ineligible. For the 39 eligible patients, there was one complete response (CR) and two partial responses (PRs), five stable/no responses, 23 increasing disease, two early deaths, and six patients whose assessment was inadequate to determine response. The response rate was therefore three of 39 or 8% (95% confidence interval [CI], 2% to 21%). The median survival time for the 39 eligible patients was 5 months. The most common toxicities were anemia, leukopenia/granulocytopenia, malaise/fatigue, nausea/vomiting, alopecia, thrombocytopenia, paresthesias, and liver function abnormalities. There was one death due to sepsis. CONCLUSION: Single-agent paclitaxel in this dose and schedule has minimal activity in pancreatic adenocarcinoma patients. 相似文献
10.
Haynes Stephen N.; Lemsky Carolyn; Sexton-Radek Kathy 《Canadian Metallurgical Quarterly》1987,18(5):515
Findings from several studies have indicated that the scientist-practitioner model (which stresses the integration of research into clinical practice) is infrequently adopted by practicing clinical psychologists. Although many hypotheses have been offered, there have been no empirical examinations of the reasons why clinicians infrequently engage in research. In this study, 79 practicing clinical psychologists completed a questionnaire focusing on perceived impediments to clinical research. A number of inhibiting factors were identified, but the intrinsic and extrinsic contingencies associated with the conduct of research were most salient. Other concerns included ethics, the impact of research on the clinical process, and the unavailability of appropriate research designs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献