全文获取类型
收费全文 | 310篇 |
免费 | 24篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 63篇 |
金属工艺 | 5篇 |
机械仪表 | 6篇 |
建筑科学 | 19篇 |
能源动力 | 12篇 |
轻工业 | 41篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 19篇 |
一般工业技术 | 61篇 |
冶金工业 | 68篇 |
原子能技术 | 1篇 |
自动化技术 | 33篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 20篇 |
2012年 | 15篇 |
2011年 | 22篇 |
2010年 | 17篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 3篇 |
2006年 | 9篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 11篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有334条查询结果,搜索用时 375 毫秒
91.
This study examines the utility of a sleeve anastomosis with comparison to conventional end to end anastomosis. Thirty New Zealand white rabbits were randomized to sleeve (n = 15) or end-to-end (n = 15) small bowel anastomosis. Five rabbits of each group were sacrificed at 3 days, 7 days, and 6 weeks. Anastomoses were assessed for integrity, bursting strength, and stenosis and examined histologically. Ten control specimens of small bowel were tested for bursting pressure. Three rabbits died postoperatively (1 sleeve and 2 end-to-end). A fourth rabbit (sleeve) was sacrificed early at 3 weeks and had a total stenosis at the anastomosis. The remaining 26 rabbits were reoperated at the prescribed times. There was no evidence of infection or dehiscence in any of these rabbits. Both end-to-end and sleeve anastomoses were equivalent for bursting pressure at all times and, at 7 days and 6 weeks, were similar to controls. The stenotic index revealed no evidence of proximal dilation suggestive of obstruction in the 26 rabbits. For sleeve anastomoses the length of the projected bowel into the lumen persisted at the 6-week stage. Histologically there was good evidence of healing in both the sleeve and end-to-end anstomoses and the serosal surface of the sleeved bowel had epithelialized. Sleeve anastomosis has been demonstrated to heal well and to be as strong as conventional end-to-end anastomosis. Further studies are warranted to determine its role in intestinal anastomosis and potential as a valve. 相似文献
92.
Xing Zhang Lijun Yin Jeffrey F. Cohn Shaun Canavan Michael Reale Andy Horowitz Peng Liu Jeffrey M. Girard 《Image and vision computing》2014
Facial expression is central to human experience. Its efficiency and valid measurement are challenges that automated facial image analysis seeks to address. Most publically available databases are limited to 2D static images or video of posed facial behavior. Because posed and un-posed (aka “spontaneous”) facial expressions differ along several dimensions including complexity and timing, well-annotated video of un-posed facial behavior is needed. Moreover, because the face is a three-dimensional deformable object, 2D video may be insufficient, and therefore 3D video archives are required. We present a newly developed 3D video database of spontaneous facial expressions in a diverse group of young adults. Well-validated emotion inductions were used to elicit expressions of emotion and paralinguistic communication. Frame-level ground-truth for facial actions was obtained using the Facial Action Coding System. Facial features were tracked in both 2D and 3D domains. To the best of our knowledge, this new database is the first of its kind for the public. The work promotes the exploration of 3D spatiotemporal features in subtle facial expression, better understanding of the relation between pose and motion dynamics in facial action units, and deeper understanding of naturally occurring facial action. 相似文献
93.
The methods normally used to calculate daylight illuminance of rooms are limited in their capacity to model different sky luminance distributions and different window glazing properties. A spreadsheet-based model is presented in this paper using first-principle calculations, which allows for a free choice of sky luminance distribution and glazing material properties. The glazing is specified in terms of material refractive index, absorption coefficient and thickness, and may be either single or double glazed. The calculations need to be repeated for each of a large number of small elements of window area, which is easily achieved using a spreadsheet. Use is illustrated by comparing the calculation of sky components with standard published data, and demonstrating the effect of substituting double for single glazing. The model was developed for educational use, but would also be useful for designers who need to investigate quickly the effect of altering glazing properties and sky conditions, without recourse to specialist software. 相似文献
94.
为检验螺钉在室外暴露情况下的抗腐蚀性能,伊利诺建筑产品Buildex中国于2008年开展了一项科研项目,称作'真实自然环境测试'。自2009年,该项目受到中国武汉材料保护研究所的支持和监督。区别于实验室内单一模拟循环条件,唯有在真实自然环境中才能测试使用在建筑中的螺钉同时经受酸雨,盐雾,潮湿和紫外线这四大主要环境腐蚀考验的情况。Buildex是目前世界上唯一实施真实自然环境测试的建筑用轻钢围护系统螺钉专业制造公司。 相似文献
95.
Employing a structural equation model to evaluate a measurement scale can be challenging, especially for a multidimensional scale that contains many items. We describe two issues that can contribute to the poor fit of such models: the statistical power associated with the test of a large measurement scale; and the degree of correlation between items and factors within the scale. These issues are not well understood, so our purpose is to explain them at an applied level, clarify their practical implications for tests of measurement scales and other large structural equation models, and discuss potential strategies for addressing them. 相似文献
96.
Widely used in manufacturing, fixtures have a direct impact upon product manufacturing quality, productivity and cost, so much attention has already been paid to the research of computer aided fixture design (CAFD) and many achievements in this field have been reported.In this paper, a literature survey of computer aided fixture design and automation over the past decade is proposed. First, an introduction is given on the fixture applications in industry. Then, significant works done in the CAFD field, including their approaches, requirements and working principles are discussed. Finally, some prospective research trends are also discussed. 相似文献
97.
CM Apfel B Takács M Fountoulakis M Stieger W Keck 《Canadian Metallurgical Quarterly》1999,181(2):483-492
The prenyltransferase undecaprenyl pyrophosphate synthetase (di-trans,poly-cis-decaprenylcistransferase; EC 2.5.1.31) was purified from the soluble fraction of Escherichia coli by TSK-DEAE, ceramic hydroxyapatite, TSK-ether, Superdex 200, and heparin-Actigel chromatography. The protein was labeled with the photolabile analogue of the farnesyl pyrophosphate analogue (E, E)-[1-3H]-(2-diazo-3-trifluoropropionyloxy)geranyl diphosphate and was detected on a sodium dodecyl sulfate-polyacrylamide gel as a protein with an apparent molecular mass of 29 kDa. This protein band was cut out from the gel, trypsin digested, and subjected to matrix-assisted laser desorption ionization mass spectrometric analysis. Comparison of the experimental data with computer-simulated trypsin digest data for all E. coli proteins yielded a single match with a protein of unassigned function (SWISS-PROT Q47675; YAES_ECOLI). Sequences with strong similarity indicative of homology to this protein were identified in 25 bacterial species, in Saccharomyces cerevisiae, and in Caenorhabditis elegans. The homologous genes (uppS) were cloned from E. coli, Haemophilus influenzae, and Streptococcus pneumoniae, expressed in E. coli as amino-terminal His-tagged fusion proteins, and purified over a Ni2+ affinity column. An untagged version of the E. coli uppS gene was also cloned and expressed, and the protein purified in two chromatographic steps. We were able to detect Upp synthetase activity for all purified enzymes. Further, biochemical characterization revealed no differences between the recombinant untagged E. coli Upp synthetase and the three His-tagged fusion proteins. All enzymes were absolutely Triton X-100 and MgCl2 dependent. With the use of a regulatable gene disruption system, we demonstrated that uppS is essential for growth in S. pneumoniae R6. 相似文献
98.
A Comparative Evaluation of Short-Term Streamflow Forecasting Using Time Series Analysis and Rainfall-Runoff Models in eWater Source 总被引:4,自引:4,他引:0
Dushmanta Dutta Wendy D. Welsh Jai Vaze Shaun S. H. Kim David Nicholls 《Water Resources Management》2012,26(15):4397-4415
Over the past few decades, many numerical streamflow prediction techniques using observed time series (TS) have been developed and widely used in water resources planning and management. Recent advances in quantitative rainfall forecasting by numerical weather prediction (NWP) models have made it possible to produce improved streamflow forecasts using continuous rainfall-runoff (RR) models. In the absence of a suitable integrated system of NWP, RR and river system models, river operators in Australia mostly use spreadsheet-based tools to forecast streamflow using gauged records. The eWater Cooperative Research Centre of Australia has recently developed a new generation software package called eWater Source, which allows a seamless integration of continuous RR and river system models for operational and planning purposes. This paper presents the outcomes of a study that was carried out using Source for a comparative evaluation of streamflow forecasting by several well-known TS based linear techniques and RR models in two selected sub-basins in the upper Murray river system of the Murray-Darling Basin in Australia. The results were compared with the actual forecasts made by the Murray River operators and the observed data. The results show that while streamflow forecasts by the river operators were reasonably accurate up to day 3 and traditional TS based approaches were reasonably accurate up to 2?days. Well calibrated RR models can provide better forecasts for longer periods when using high quality quantitative precipitation forecasts. The river operators tended to underestimate large magnitude flows. 相似文献
99.
Ryan D. Boehm Shaun D. Gittard Jacqueline M. H. Byrne Anand Doraiswamy Jonathan J. Wilker Timothy M. Dunaway Rene Crombez Weidian Shen Yuan-Shin Lee Roger J. Narayan 《JOM Journal of the Minerals, Metals and Materials Society》2010,62(7):56-60
Piezoelectric inkjet printing is a noncontact process that enables microscale processing of biological materials. In this
research summary, the use of piezoelectric inkjet printing for patterning medical adhesives and sealants, including a two-component
polyethylene glycol hydrogel-based medical sealant, an N-butyl cyanoacrylate tissue adhesive, and a mussel adhesive protein
biological adhesive, is described The effect of Fe(III) on mussel adhesive protein structure was evaluated by means of atomic
force microscopy. The ability to process microscale patterns of medical sealants and adhesives will provide an improvement
in tissue joining, including enhanced tissue integrity, reduced bond lines, and decreased adhesive toxicity. Piezoelectric
inkjet deposition of medical adhesives and sealants may be used in wound closure, fracture fixation, and microscale vascular
surgery. 相似文献
100.
Kam Ng Daniel Hellrung Khaled Ksaibati Shaun S. Wulff 《International Journal of Pavement Engineering》2018,19(1):62-74
A research focusing on the characterisation of representative local material properties was conducted to facilitate the full implementation of the Mechanistic-Empirical Pavement Design Guide for roadway designs in Wyoming. As part of the test program, falling weight deflectometer deflection data were collected from 25 test sites in Wyoming for back-calculation of subgrade resilient modulus. Also, subgrade materials from these test sites were sampled for laboratory resilient modulus measurement in accordance with the AASHTO T 307. The back-calculation is a user-dependent procedure and produces a non-unique resilient modulus estimation. To alleviate this limitation, this paper focuses on the recent development of a systematic back-calculation protocol for subgrade resilient modulus using MODCOMP6 software. The protocol is intended for use on a flexible pavement with a crushed base. The proposed procedure discusses pre-analysis checks, seed modulus adjustment, pavement structure adjustment and program termination criteria. A correlation study was conducted to correct back-calculated resilient modulus to laboratory-equivalent values. The results conclude that a non-zero intercept linear regression model provides a better correlation than the widely used zero intercept linear regression model. Furthermore, better correlations are achieved when the back-calculated resilient modulus of a lower subgrade layer and resilient modulus measured at higher laboratory test sequences Nos. 11 to 15 are considered. The non-zero model based on Mr test sequence No. 14 and lower subgrade layer yields the best correlation. For the zero model, a C-factor of 0.645 based on Mr test sequence No. 15 and lower subgrade layer yields the best correlation. 相似文献