全文获取类型
收费全文 | 923篇 |
免费 | 60篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 28篇 |
综合类 | 1篇 |
化学工业 | 198篇 |
金属工艺 | 23篇 |
机械仪表 | 7篇 |
建筑科学 | 32篇 |
矿业工程 | 2篇 |
能源动力 | 33篇 |
轻工业 | 118篇 |
水利工程 | 10篇 |
石油天然气 | 4篇 |
无线电 | 65篇 |
一般工业技术 | 110篇 |
冶金工业 | 220篇 |
原子能技术 | 1篇 |
自动化技术 | 133篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 22篇 |
2020年 | 13篇 |
2019年 | 14篇 |
2018年 | 24篇 |
2017年 | 16篇 |
2016年 | 38篇 |
2015年 | 23篇 |
2014年 | 35篇 |
2013年 | 54篇 |
2012年 | 42篇 |
2011年 | 58篇 |
2010年 | 31篇 |
2009年 | 36篇 |
2008年 | 44篇 |
2007年 | 49篇 |
2006年 | 29篇 |
2005年 | 34篇 |
2004年 | 24篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 18篇 |
1998年 | 65篇 |
1997年 | 50篇 |
1996年 | 26篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有985条查询结果,搜索用时 15 毫秒
1.
Ricardo Beristain‐Cardoso Anne‐Claire Texier Reyes Sierra‐Álvarez Jim A Field Elías Razo‐Flores Jorge Gómez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(9):1197-1203
BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH3COO?/NO3? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH3COO?/NO3? (0.85, 0.72 and 0.62) with a constant S2?/NO3? molar ratio of 0.13 were evaluated. At a CH3COO?/NO3? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N2 yield (g N2 g?1 NO3?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g?1 CH3COO?‐C consumed. Sulfide was partially oxidized to S0, and 71% of the S2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH3COO?/NO3? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N2 and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S0, with a yield of 0.92 g SO42?‐S g?1 S2? consumed. CONCLUSIONS: The CH3COO?/NO3? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S0 or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO2, S0 and N2 as the major end products. Copyright © 2008 Society of Chemical Industry 相似文献
2.
3.
P Navarro J Sarasa D Sierra S Esteban J L Ovelleiro 《Water science and technology》2005,51(1):113-120
Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower. 相似文献
4.
5.
6.
Effect of grain boundary phase on the thermal conductivity of aluminium nitride ceramics 总被引:2,自引:0,他引:2
Ching -Fong Chen M. E. Perisse A. F. Ramirez N. P. Padture H. M. Chan 《Journal of Materials Science》1994,29(6):1595-1600
AIN with high thermal conductivity was fabricated by pressureless sintering with Y2O3 as the sintering aid. The thermal conductivity was observed to increase with sintering time (up to 8 h) at 1810 °C. The distribution of the sintering aid was identified as one of the major factors influencing the thermal conductivity in AIN. Non-uniform distribution of the grain boundary phase was found to be associated with a significant amount of porosity, resulting in the enhancement of phonon scattering and thereby lowering the thermal conductivity. 相似文献
7.
J Moreno Sierra ML Maestro de las Casas J Chicharro Almarza MD Ortega Heredia J López García-Asenjo C Merino Sánchez E Blanco Jiménez A Silmi Moyano L Rsesel Estévez 《Canadian Metallurgical Quarterly》1997,50(8):855-866
OBJECTIVE: The clinical course of transitional cell carcinoma of the bladder can be difficult to predict due to its potential to invade the muscle layer and/or develop to a high grade lesion. Bladder carcinoma can arise from genetic changes that may activate the oncogenes (-c-erbB2, c-erbB1, c-myc, ras, etc.) and/or inactivate the suppressor genes (p53, Rb). The aim of the present study is to continue a study protocol on the molecular biology of bladder tumors. METHODS/RESULTS: From January, 1993 to January, 1995, 85 patients were studied. These patients were divided into two groups: the first group comprised 14 controls of urothelial tissue and the second comprised 65 cases of transitional cell carcinoma of the bladder. p53 expression was determined by an immunohistochemical method (NCL-p53-DO7 monoclonal antibody). Quantification of the p8 oncoprotein in cytosol and EGFR (epidermal growth factor receptor) in membrane was performed by ELISA (Oncogene Science) and RIA (Vienna Lab), respectively. A statistically significant relationship between the expression of p53 and EGFR with tumor stage and grade was found. Quantification of p185 and EGFR showed higher values in the tumor tissue than in the control samples, but a worse survival could not be determined. CONCLUSIONS: The present study shows that p53 expression can be considered to be a prognostic factor. It provides useful information on the aggressive behaviour of the tumor and has a direct relation with the survival rates. 相似文献
8.
The use of an HLA-compatible unrelated donor is an option for patients who require an allogeneic transplant but lack a family member match. Grafts from unrelated volunteer donors have provided long-term disease-free survival for a variable proportion of patients, depending on degree of HLA matching with the donor, patient's disease, disease stage, and age. The number of volunteers in marrow donor registries worldwide has increased to more than 2.5 million. The number of unrelated donor transplants facilitated by the US National Marrow Donor Program alone will exceed 900 this year. Progress in HLA-typing technology results in a more precise definition of donor and recipient matching and new assays have been developed with initial success to measure alloreactive T-cell precursors for selection of donors with less antihost reactivity. Prevention and treatment of graft failure, graft-versus-host disease, opportunistic infections, and Epstein-Barr virus-associated lymphoproliferative disease remain a challenge. 相似文献
9.
N. B. Kavukcuoglu E. Arteaga-Solis S. Lee-Arteaga F. Ramirez A. B. Mann 《Journal of Materials Science》2007,42(21):8788-8794
Absence of fibrillin 2 (Fbn2), a non-collagenous bone protein, causes a connective tissue disorder called congenital contractural arachnodactyly (CCA)
and has been associated with decreased bone mineral density. Nanoindentation and Raman microspectroscopy have been used to
compare the mechanical and chemical properties of cortical bone from femora of Fbn2−/− deficient mice and their wild-type controls (Fbn2+/+). It was found that Fbn2−/− bones have significantly lower hardness and elastic modulus compared to Fbn2+/+ bones, especially in the mid-cortical section. The Raman analysis showed little difference with genotype except for a decrease
in type-B carbonate substitution in the endosteal region of Fbn2−/− bones. The results indicate that Fbn2 plays a direct role in determining the mechanical properties of bone. 相似文献
10.
This paper presents the Navigation Maps Modeling approach (NMM), which provides platform independent models for characterizing navigation maps of web applications. The NMM approach is conceived to obtain a trade off between high and low-level design notations. As high-level design notations, NMM models permit architectural details that may hinder the overall understanding of the web application to be left out. As low-level design notations, NMM models can easily be transformed into detailed architectural designs, which are very valuable at coding and maintenance stages. 相似文献