全文获取类型
收费全文 | 31866篇 |
免费 | 3524篇 |
国内免费 | 2020篇 |
专业分类
电工技术 | 3051篇 |
综合类 | 3078篇 |
化学工业 | 4402篇 |
金属工艺 | 1181篇 |
机械仪表 | 1786篇 |
建筑科学 | 2785篇 |
矿业工程 | 1115篇 |
能源动力 | 1100篇 |
轻工业 | 1509篇 |
水利工程 | 1168篇 |
石油天然气 | 1729篇 |
武器工业 | 733篇 |
无线电 | 3266篇 |
一般工业技术 | 3099篇 |
冶金工业 | 2160篇 |
原子能技术 | 532篇 |
自动化技术 | 4716篇 |
出版年
2024年 | 119篇 |
2023年 | 448篇 |
2022年 | 689篇 |
2021年 | 869篇 |
2020年 | 969篇 |
2019年 | 896篇 |
2018年 | 892篇 |
2017年 | 1184篇 |
2016年 | 1313篇 |
2015年 | 1336篇 |
2014年 | 1909篇 |
2013年 | 1919篇 |
2012年 | 2019篇 |
2011年 | 2364篇 |
2010年 | 1758篇 |
2009年 | 1924篇 |
2008年 | 1738篇 |
2007年 | 1988篇 |
2006年 | 1967篇 |
2005年 | 1590篇 |
2004年 | 1343篇 |
2003年 | 1210篇 |
2002年 | 1024篇 |
2001年 | 863篇 |
2000年 | 703篇 |
1999年 | 526篇 |
1998年 | 419篇 |
1997年 | 350篇 |
1996年 | 289篇 |
1995年 | 267篇 |
1994年 | 235篇 |
1993年 | 153篇 |
1992年 | 140篇 |
1991年 | 106篇 |
1990年 | 123篇 |
1989年 | 69篇 |
1988年 | 66篇 |
1987年 | 66篇 |
1986年 | 41篇 |
1985年 | 145篇 |
1984年 | 246篇 |
1983年 | 282篇 |
1982年 | 210篇 |
1981年 | 312篇 |
1980年 | 120篇 |
1979年 | 39篇 |
1978年 | 41篇 |
1977年 | 16篇 |
1975年 | 22篇 |
1974年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Biosolids reduction model by return activated sludge ozonation was validated by simulating nitrification data compiled from our pilot-scale and the literature studies. Then, a global sensitivity analysis (GSA) was performed to identify influential and non-influential parameters for biosolids reduction efficiency, change in specific nitrification activity (SNA), and alteration to expected nitrification stability. In general, the model outputs were sensitive to operational and ozone reaction parameters, but not to biochemical parameters. For operational parameters, mainly temperature and initial solids retention time (SRT) influenced all model outputs. For biosolids reduction, increase in the degradability of the influent COD decreased the reduction efficiency. For SNA, the changes were highly dependent on the influent TKN/COD ratio. Our findings also imply that the stability of the nitrification process in ozonated systems should be enhanced at constant MLVSS for warm temperatures, but could be reduced at temperatures below 12 °C and aerated SRTs below 10 days. 相似文献
3.
Using a comprehensive set of drop weight impact test data (h50) newly compiled from literature for 308 materials, a recent approach to predict impact sensitivities of nitro compounds is generalized to most explosive substances of interest. Compared to previous ones, this procedure is more thoroughly validated and exhibits a good predictive value. Furthermore, it yields new insight into the physical mechanisms involved, explaining for instance the unexpected desensitization of some oxygen-deficient triazoles upon nitration. 相似文献
4.
Hwansoo Lee Dongwon Lim Hyerin Kim Andrew P. Ciganek 《Behaviour & Information Technology》2015,34(1):45-56
Many e-commerce companies collect users’ personal data for marketing purposes despite privacy concerns. Information-collecting companies often offer a monetary reward to users to alleviate privacy concerns and ease the collection of personal information. This study focused on the negative effects of monetary rewards on both information privacy concerns (IPC) and information disclosure. A survey approach was used to collect data and 370 final responses were analysed using a two-way analysis of variance and a binomial logistic regression model. The results show that monetary rewards increase IPC when an information-collecting company requires sensitive information. Additional results indicate that building trust is a more effective way of collecting personal data. This study identifies how organisations can best execute information-collection activities and contributes additional insights for academia and practitioners. 相似文献
5.
Temperature history can have a significant effect on the strength of water-saturated chalk.In this study,hydrostatic stress cycles are applied to understand the mechanical response of chalk samples exposed to temperature cycling between each stress cycle,compared to the samples tested at a constant temperature.The total accumulated strain during a stress cycle and the irreversible strain are reported.Chalk samples from Kansas(USA)and Mons(Belgium),with different degrees of induration(i.e.amount of contact cementation),were used.The samples were saturated with equilibrated water(polar)and nonpolar Isopar H oil to quantify water weakening.All samples tested during 10 stress cycles with varying temperature(i.e.temperature cycled in between each stress cycle)accumulated more strain than those tested at constant temperatures.All the stress cycles were performed at 30℃.The two chalk types behaved similarly when saturated with Isopar H oil,but differently when saturated with water.When saturated with water,the stronger Kansas chalk accumulated more total strain and more irreversible strain within each stress cycle than the weaker Mons chalk. 相似文献
6.
Suitability,efficiency and microbiological safety of novel physical technologies for the processing of ready‐to‐eat meals,meats and pumpable products 下载免费PDF全文
Alexandros Ch. Stratakos Anastasios Koidis 《International Journal of Food Science & Technology》2015,50(6):1283-1302
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products. 相似文献
7.
This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO2 : O2 : N2 = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
8.
9.
超声波强化原油破乳电脱盐技术的工业实践 总被引:9,自引:1,他引:8
报道了采用超声波强化原油破乳电脱盐技术的开发与工业应用.经过实验室开发确定的超声波强化原油破乳电脱盐专利技术--超声波-电场联合破乳脱盐组合技术采用顺逆流方式.该技术于2003年9月在齐鲁分公司完成工业应用试验后,超声波强化原油破乳设备直接投入生产运行,在不加入化学破乳剂的情况下,可使胜利混输原油(平均盐浓度为50 mg/L,平均水质量分数为0.5%~1.0%)脱后盐浓度低于3 mg/L,水质量分数小于0.3%. 相似文献
10.