全文获取类型
收费全文 | 299篇 |
免费 | 19篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 67篇 |
金属工艺 | 4篇 |
机械仪表 | 8篇 |
建筑科学 | 14篇 |
能源动力 | 7篇 |
轻工业 | 41篇 |
无线电 | 17篇 |
一般工业技术 | 68篇 |
冶金工业 | 64篇 |
原子能技术 | 1篇 |
自动化技术 | 25篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 23篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 13篇 |
2012年 | 16篇 |
2011年 | 25篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有318条查询结果,搜索用时 437 毫秒
91.
The need for structural rehabilitation of concrete structures all over the world is well known, and a great amount of research is going on in this field. The use of carbon fiber-reinforced polymer (CFRP) plate bonding has been shown to be a competitive method with regard to both structural performance and economic factors. This method consists of bonding a thin carbon-fiber laminate or sheet to the surface of the structure to act as an outer reinforcement layer. However, most research in this area has been undertaken to study flexural behavior. This paper deals with shear strengthening of reinforced concrete members by use of CFRP. Tests on rectangular beams 3.5 to 4.5 m long have been undertaken to study different parameters, such as fatigue, anchorage, and others. The strain field in shear spans of beams simultaneously subjected to shear and bending is also studied. The tests presented also contribute to the existing literature on tests of concrete members strengthened for increased shear capacity. 相似文献
92.
The cyclic deformation behaviour of Mg – base alloy AZ31 The cyclic deformation behaviour of Mg – base alloy AZ31 was investigated in stress controlled tension-, compression-tests. Experiments with zero mean stress (R = -1) as well as with tensile or compression mean stress (R = 0, R = - ∞ resp.) were carried out. Cyclic strain hardening and a pronounced anisotropy of strength during the first loading cycles was observed with higher yield strength in tension compared with compression. Consequently, in tests with zero mean stress cyclic creep and compressive mean strains occured. 相似文献
93.
Presents a broad overview of the emerging enterprise of transpersonal ("Fourth Force") psychotherapy. Contrasts are drawn between transpersonal and other major schools of therapy. Within the transpersonal realm of psychotherapy, issues of process, content, stages, goals, and context are discussed, and conceptual distinctions are made. The difference between enlightenment and change is elucidated, and techniques associated with change are described. The optimal attributes of a transpersonal therapist are outlined, and the limitations—especially the problem of proof of transcendent phenomena—of this psychological realm are examined. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
Zinn B Meigs LC Harvey CF Haggerty R Peplinski WJ Von Schwerin CF 《Environmental science & technology》2004,38(14):3916-3926
Solute transport displaying mass transfer behavior (i.e., tailing) occurs in many aquifers and soils. Spatial patterns of hydraulic conductivity may play a role because of both advection and diffusion through isolated low conductivity areas. We demonstrated such processes in laboratory experiments designed to visualize solute transport through a thin chamber (40 cm x 20 cm x 0.64 cm thick) packed with glass beads and containing circular emplacements of smaller glass beads with lower conductivity. The experiments used three different contrasts of conductivity between the large-bead matrix and the emplacements, targeting three different regimes of solute transport: low contrast, targeting macrodispersion; intermediate contrast, targeting advection-dominated mass transfer between the high-conductivity regions and the emplacements; and high contrast, targeting diffusion-dominated mass transfer. Use of a strong light source, a high-resolution CCD camera, and a colorimetric dye produced images with a spatial resolution of about 400 microm and a concentration range of approximately 2 orders of magnitude. These images confirm the existence of the three different regimes, and we observed tailing driven by both advection and diffusion. Outflow concentration measured by spectrophotometer achieved 3 orders of magnitude in concentration range and showed good agreement with known models in the case of dispersion and diffusive mass transfer, with estimated parameters close to a priori predictions. Existing models for diffusive mass transfer did notfitthe breakthrough curves from the intermediate-contrast chamber, but a model of slow advection through cylinders did. Thus, both breakthrough curves and chamber images confirm that different contrasts in small-scale K lead to different regimes of solute transport and thus require different models of upscaled solute transport. 相似文献
95.
Six anticancer drugs have been eluted on a polystyrene-divinylbenzene (PS-DVB) column with buffered superheated water as the mobile phase. The temperature range studied was from ambient temperature up to 160 degrees C, and the pH of the water was adjusted to 11.5 and 3.5 with phosphate buffer. It was possible to separate the substances 5-fluorouracil (5-FU), methotrexate (MTX), 7-hydroxymethotrexate (7-OH-MTX), and etoposide (VP-16) in one chromatographic run. The separation of these substances was optimized when adjusting the pH from 11.5 to 3.5, resulting in a total elution time of less than 13 min. Furthermore, retention factors of all of the investigated substances were measured at different temperatures and pH values. 相似文献
96.
Many developing nations, such as India have embarked upon wind energy programs for areas experiencing high average wind speeds throughout the year. One of the states in India that is actively pursuing wind power generation programs is Tamil Nadu. Within this state, Muppandal area is one of the identified regions where wind farm concentration is high. Wind energy engineers are interested in studies that aim at assessing the output of wind farms, for which, artificial intelligence techniques can be usefully adapted. The present paper attempts to apply this concept for assessment of the wind energy output of wind farms in Muppandal, Tamil Nadu (India). Field data are collected from seven wind farms at this site over a period of 3 years from April 2002 to March 2005 and used for the analysis and prediction of power generation from wind farms. The model has been developed with the help of neural network methodology. It involves three input variables—wind speed, relative humidity and generation hours and one output variable-energy output of wind farms. The modeling is done using MATLAB toolbox. The model accuracy is evaluated by comparing the simulated results with the actual measured values at the wind farms and is found to be in good agreement. 相似文献
97.
98.
Ergothioneine (ET) is a unique natural antioxidant. We have examined the origin of ET in zebrafish. There was virtually no ET, measured by LC–MS, in most tank vegetation (plant, green and red alga). However, ET was detected in a Phormidium sample, a cyanobacterium. In commercial fish feed preparations, ET content increased with the content of cyanobacteria Arthrospira platensis or Arthrospira maxima (Spirulina). High levels of ET (up to 0.8 mg per g dry mass) were measured in cyanobacteria preparations sold as dietary supplements for humans and in fresh Scytonema and Oscillatoria cultures. Cyanobacteria contained as much ET as King Oyster mushrooms (Pleurotus eryngii). All samples with substantial ET content also contained the biosynthesis intermediate hercynine; this strongly suggests that cyanobacteria synthesise ET de novo. In conclusion, our data establish that cyanobacteria can produce high levels of ergothioneine. Spirulina is a novel, safe, accessible, and affordable source of ergothioneine for humans. 相似文献
99.
100.
Mesoscopic simulation of selective beam melting processes 总被引:2,自引:0,他引:2
Carolin Körner Elham Attar Peter Heinl 《Journal of Materials Processing Technology》2011,211(6):978-987