全文获取类型
收费全文 | 219篇 |
免费 | 28篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 45篇 |
金属工艺 | 2篇 |
机械仪表 | 9篇 |
建筑科学 | 15篇 |
能源动力 | 5篇 |
轻工业 | 44篇 |
水利工程 | 5篇 |
无线电 | 4篇 |
一般工业技术 | 34篇 |
冶金工业 | 55篇 |
自动化技术 | 27篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 5篇 |
1999年 | 2篇 |
1998年 | 22篇 |
1997年 | 13篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 12 毫秒
141.
142.
P Tudela C Queralt M Giménez A Carreres J Tor N Sopena J Valencia 《Canadian Metallurgical Quarterly》1998,111(6):201-204
OBJECTIVES: To investigate the prevalence and risk factors of bacterial vaginosis (BV) in a pregnant population of Barcelona (Spain). MATERIAL AND METHODS: 301 pregnant women controlled in the Hospital Clinic i Provincial (HCP) of Barcelona were enrolled in the study. Complete epidemiological information, and vaginal samples were available in 293 women. BV was diagnosed by Gram stain of vaginal smear (Nugent's criteria). RESULTS: BV was detected in 22 pregnant women (7.5%; 95% CI: 4.6-10.5%). There was no association between race, parity, education, marital status, smoking and drug use, and the presence of BV. Non-use of birth control method (72.3% vs 34.4%; p < 0.0001), presence of sexually transmitted diseases (STD) during pregnancy (22.7% vs 3.7%; p < 0.0001), HIV seropositivity (13.6% vs 2.9%; p = 0.041) and presence of symptoms of vaginitis (40.9% vs 13.3%; p = 0.009) were significantly associated with the presence of BV. CONCLUSIONS: The prevalence of BV in a pregnant population of Barcelona (Spain) is 7.5%. Further work is needed to evaluate the usefulness of BV as a prescreening marker for STD and HIV infection. The Gram stain provides an inexpensive, fast and easy method to diagnose BV, and may allow us to screen, treat and prevent the morbidity and mortality associated with it. 相似文献
143.
In this paper, five hydrogen storage systems for automobiles are evaluated using the fuzzy analytic hierarchy process (AHP) in respect to eight criteria. The hydrogen storage systems for automobiles to be evaluated are 350 bar compressed gas hydrogen, 700 bar compressed gas hydrogen, liquefied hydrogen, metal hydride and chemical hydride. The selected criteria used in the evaluation of five hydrogen storage systems are weight efficiency, volume efficiency, system cost, energy efficiency, cycle life, refueling time, safety and infrastructure. According to the evaluation, compressed gas hydrogen ranks the highest in classification in Korea. Liquefied hydrogen ranks higher than metal hydride and chemical hydride. If the infrastructure for liquefied hydrogen were good in Korea, liquefied hydrogen may rank the highest in classification. Also, it should be noted that the rank of hydrogen storage systems can be changed according to the future technological developments. 相似文献
144.
Sureda R Casas I Giménez J de Pablo J Quiñones J Zhang J Ewing RC 《Environmental science & technology》2011,45(6):2510-2515
The stability of soddyite under electron irradiation has been studied over the temperature range of 25-300 °C. At room temperature, soddyite undergoes a crystalline-to-amorphous transformation (amorphization) at a total dose of 6.38 × 10(8) Gy. The electron beam irradiation results suggest that the soddyite structure is susceptible to radiation-induced nanocrystallization of UO(2). The temperature dependence of amorphization dose increases linearly up to 300 °C. A thermogravimetric and calorimetric analysis (TGA-DSC) combined with X-ray diffraction (XRD) indicates that soddyite retains its water groups up to 400 °C, followed by the collapse of the structure. Based on thermal analysis of uranophane, the removal of some water groups at relatively low temperatures provokes the collapse of the uranophane structure. This structural change appears to be the reason for the increase of amorphization dose at 140 °C. According to the results obtained, radiation field of a nuclear waste repository, rather than temperature effects, may cause changes in the crystallinity of soddyite and affect its stability during long-term storage. 相似文献
145.
146.
Gregorio Bernabé Javier Cuenca Luis Pedro García Domingo Giménez 《The Journal of supercomputing》2014,70(2):830-844
This paper presents an enhanced auto-optimization method to run the 3D-Fast Wavelet Transform on different computing units in a system (GPU, MIC, CPU). The proposed method automatically selects a set of parameter values (block size, number of streams and number of threads) in order to reduce the total execution time, obtaining performances close to the optimal and decreasing the number of evaluations needed. 相似文献
147.
Melissa M. Baustian Georgia Mavrommati Erin A. Dreelin Peter Esselman Steven R. Schultze Leilei Qian Tiong Gim Aw Lifeng Luo Joan B. Rose 《Journal of Great Lakes research》2014
There is a growing concern about continued impairment of aquatic ecosystems resulting from increasing population size, land use, climate change, and the feedbacks that may harm human well-being. We describe a 100 year multi-disciplinary overview of changes in Lake St. Clair, North America to identify knowledge gaps and needs to build the foundation for creating coupled human and natural system models. Our historical analysis indicates that the socioeconomic dynamics are inextricably linked to the urban dynamics of the Detroit metropolitan area. Environmental degradation and human health issues led to the adoption of relevant policies, including construction of wastewater treatment facilities by the 1960s. Climate trends during the 100-year period indicate a wetter region, which is influencing lake levels. Since the mid-1980s and 90s invasive zebra and quagga mussels (Dreissena polymorpha and Dreissena rostriformis bugenis) have significantly altered the ecological structure and function of the lake. Waterborne illnesses due to contaminated drinking water were once an issue but current human health risks have shifted to contaminated recreational waters and coastal pollution. Key research needs for building coupled models include geo-referencing socioeconomic and ecological data to accurately represent the processes occurring within the political and watershed boundaries; assessing ecosystem services for human well-being; and developing research hypotheses and management options regarding interactions among land use, people and the lake. Lake St. Clair has gone through extensive changes, both socioeconomically and ecologically over the last 100 years and we suggest that it serves as a useful case study for the larger Great Lakes region. 相似文献
148.
Influence of antioxidant compounds,total sugars and genetic background on the chilling injury susceptibility of a non‐melting peach (Prunus persica (L.) Batsch) progeny 下载免费PDF全文
149.
Sánchez-Escalante A Djenane D Torrescano G Giménez B Beltrán JA Roncalés P 《Meat science》2003,64(1):59-67
The aim of this research was to reevaluate the inhibition of oxidative changes in beef patties packaged in modified atmosphere (70% O(2)+20% CO(2)+10% N(2)) by carnosine (50 mM). The need for reevaluation was because it had been postulated that hydrazine present as contaminant in commercial carnosine could contribute to the antioxidant activity. Beef patties with either commercial or purified hydrazine-free carnosine were stored at 2±1?°C for 20 days and evaluated for colour (a* and H*), TBARS, metmyoglobin formation (% of total surface myoglobin), psychrotrophic microbial counts and sensory odour. Results indicated that both forms of carnosine effectively inhibited lipid oxidation and color changes in beef patties throughout storage, showing no significant differences (P>0.05) between them. It was concluded that the antioxidant effect was brought about by the carnosine molecule and not by hydrazine. 相似文献
150.
The application of flue gas desulphurisation (FGD) gypsum as an acid soil ameliorant was studied in order to establish the possible detrimental effects on plants and animals feeding on them caused by the high fluoride content in this by-product. A greenhouse experiment was conducted under controlled conditions to determine the F accumulation by two plant species (alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.)) grown in acid soils amended with different FGD gypsum doses (0-10%). The F concentrations in plant aerial parts were comprised in the range 22-65 mg kg−1, and those in plant roots varied from 49 to 135 mg kg−1. The F contents in the above-ground plant tissues showed to decrease with the FGD gypsum application rate, whereas an inverse trend was manifested by plant roots. The increase in the soil content of soluble Ca as a result of the FGD gypsum addition seemed to play an important role in limiting the translocation of F to plant aerial parts. 相似文献