全文获取类型
收费全文 | 39914篇 |
免费 | 1623篇 |
国内免费 | 103篇 |
专业分类
电工技术 | 490篇 |
综合类 | 62篇 |
化学工业 | 8541篇 |
金属工艺 | 790篇 |
机械仪表 | 851篇 |
建筑科学 | 2679篇 |
矿业工程 | 205篇 |
能源动力 | 1172篇 |
轻工业 | 3720篇 |
水利工程 | 295篇 |
石油天然气 | 111篇 |
武器工业 | 2篇 |
无线电 | 3015篇 |
一般工业技术 | 7062篇 |
冶金工业 | 5743篇 |
原子能技术 | 321篇 |
自动化技术 | 6581篇 |
出版年
2023年 | 276篇 |
2022年 | 459篇 |
2021年 | 959篇 |
2020年 | 636篇 |
2019年 | 679篇 |
2018年 | 901篇 |
2017年 | 787篇 |
2016年 | 998篇 |
2015年 | 869篇 |
2014年 | 1167篇 |
2013年 | 2535篇 |
2012年 | 1895篇 |
2011年 | 2568篇 |
2010年 | 1824篇 |
2009年 | 1824篇 |
2008年 | 2082篇 |
2007年 | 1828篇 |
2006年 | 1616篇 |
2005年 | 1423篇 |
2004年 | 1237篇 |
2003年 | 1102篇 |
2002年 | 1067篇 |
2001年 | 680篇 |
2000年 | 687篇 |
1999年 | 746篇 |
1998年 | 1128篇 |
1997年 | 836篇 |
1996年 | 724篇 |
1995年 | 571篇 |
1994年 | 565篇 |
1993年 | 556篇 |
1992年 | 427篇 |
1991年 | 362篇 |
1990年 | 331篇 |
1989年 | 364篇 |
1988年 | 306篇 |
1987年 | 291篇 |
1986年 | 283篇 |
1985年 | 374篇 |
1984年 | 343篇 |
1983年 | 298篇 |
1982年 | 255篇 |
1981年 | 295篇 |
1980年 | 212篇 |
1979年 | 242篇 |
1978年 | 229篇 |
1977年 | 241篇 |
1976年 | 274篇 |
1975年 | 197篇 |
1974年 | 177篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
SPEEK/cSMM membrane for simultaneous electricity generation and wastewater treatment in microbial fuel cell
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
12.
13.
14.
15.
Angelico Mendy Nervana Metwali Sarah S. Perry Elizabeth A. Chrischilles Kai Wang Peter S. Thorne 《Indoor air》2020,30(1):88-97
Endotoxin exacerbates asthma. We designed the Louisa Environmental Intervention Project (LEIP) and assessed its effectiveness in reducing household endotoxin and improving asthma symptoms in rural Iowa children. Asthmatic school children (N = 104 from 89 homes) of Louisa and Keokuk counties in Iowa (aged 5-14 years) were recruited and block-randomized to receive extensive (education + professional cleaning) or educational interventions. Environmental sampling collection and respiratory survey administration were done at baseline and during three follow-up visits. Mixed-model analyses were used to assess the effect of the intervention on endotoxin levels and asthma symptoms in the main analysis and of endotoxin reduction on asthma symptoms in exploratory analysis. In the extensive intervention group, dust endotoxin load was significantly reduced in post-intervention visits. The extensive compared with the educational intervention was associated with significantly decreased dust endotoxin load in farm homes and less frequent nighttime asthma symptoms. In exploratory analysis, dust endotoxin load reduction from baseline was associated with lower total asthma symptoms score (Odds ratio: 0.52, 95% confidence interval: 0.29-0.92). In conclusion, the LEIP intervention reduced household dust endotoxin and improved asthma symptoms. However, endotoxin reductions were not sustained post-intervention by residents. 相似文献
16.
Robert Brooke Manrico Fabretto Samuel Pering Eliza Switalska Lachlan Reeks Drew Evans Peter Murphy 《应用聚合物科学杂志》2015,132(26)
A study using three different pairs of electrochromic polymers (ECPs) synthesized onto plaques by means of a modified vapor phase polymerization (VPP) technique is presented. Restriction of the respective polymerization times, allowed both faster and slower polymerizing monomers to be controlled, and produced blended plaques with visually diffuse interfaces. The ECPs within the blended plaques retain their individual electrochromic behavior and when encapsulated into an electrochromic device, show outstanding optical switching performance with little degradation evident over 10,000 cycles, coupled with a switching time of the order of 1 second. Blends also allow multiple diffuse color changes within an electrochromic device, due to the difference in oxidation potentials of the individual ECPs, making them candidates for adaptive camouflage use. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42158. 相似文献
17.
18.
19.
Sebastian Roth Peter Stockinger Jakob Steff Simon Steimle Dr. Viktor Sautner Prof. Dr. Kai Tittmann Prof. Dr. Jürgen Pleiss Prof. Dr. Michael Müller 《Chembiochem : a European journal of chemical biology》2020,21(18):2615-2619
The family of NAD(P)H-dependent short-chain dehydrogenases/reductases (SDRs) comprises numerous biocatalysts capable of C=O or C=C reduction. The highly homologous noroxomaritidine reductase (NR) from Narcissus sp. aff. pseudonarcissus and Zt_SDR from Zephyranthes treatiae, however, are SDRs with an extended imine substrate scope. Comparison with a similar SDR from Asparagus officinalis (Ao_SDR) exhibiting keto-reducing activity, yet negligible imine-reducing capability, and mining the Short-Chain Dehydrogenase/Reductase Engineering Database indicated that NR and Zt_SDR possess a unique active-site composition among SDRs. Adapting the active site of Ao_SDR accordingly improved its imine-reducing capability. By applying the same strategy, an unrelated SDR from Methylobacterium sp. 77 (M77_SDR) with distinct keto-reducing activity was engineered into a promiscuous enzyme with imine-reducing activity, thereby confirming that the ability to reduce imines can be rationally introduced into members of the “classical” SDR enzyme family. Thus, members of the SDR family could be a promising starting point for protein approaches to generate new imine-reducing enzymes. 相似文献
20.