全文获取类型
收费全文 | 3885篇 |
免费 | 413篇 |
国内免费 | 183篇 |
专业分类
电工技术 | 17篇 |
综合类 | 326篇 |
化学工业 | 1969篇 |
金属工艺 | 83篇 |
机械仪表 | 67篇 |
建筑科学 | 444篇 |
矿业工程 | 29篇 |
能源动力 | 326篇 |
轻工业 | 776篇 |
水利工程 | 48篇 |
石油天然气 | 141篇 |
武器工业 | 9篇 |
无线电 | 30篇 |
一般工业技术 | 75篇 |
冶金工业 | 43篇 |
原子能技术 | 15篇 |
自动化技术 | 83篇 |
出版年
2024年 | 28篇 |
2023年 | 102篇 |
2022年 | 387篇 |
2021年 | 359篇 |
2020年 | 175篇 |
2019年 | 133篇 |
2018年 | 132篇 |
2017年 | 127篇 |
2016年 | 161篇 |
2015年 | 141篇 |
2014年 | 221篇 |
2013年 | 225篇 |
2012年 | 247篇 |
2011年 | 240篇 |
2010年 | 166篇 |
2009年 | 195篇 |
2008年 | 192篇 |
2007年 | 186篇 |
2006年 | 207篇 |
2005年 | 152篇 |
2004年 | 115篇 |
2003年 | 101篇 |
2002年 | 79篇 |
2001年 | 45篇 |
2000年 | 40篇 |
1999年 | 39篇 |
1998年 | 25篇 |
1997年 | 35篇 |
1996年 | 22篇 |
1995年 | 23篇 |
1994年 | 30篇 |
1993年 | 30篇 |
1992年 | 18篇 |
1991年 | 23篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有4481条查询结果,搜索用时 0 毫秒
1.
2.
P. S. Lawson 《Biomass & bioenergy》1992,2(1-6):319-330
In recent years it has been recognised by an increasing number of nations that there is considerable energy potential within MSW. As a result many countries have established R,D& D programmes to examine methods of exploiting this potential. The IEA's MSW Conversion Activity was set up in 1986 to provide an infrastructure for sharing information and co-ordinating work in this area internationally. This Activity was extended in 1989 and currently a total of 9 nations participate in it.
To cope with the wide scope of the area (encompassing both biological and thermal processing of MSW) the Activity was divided into three subgroups or Expert Working Groups (EWGs). Each of these dealt with a distinct area of expertise:
- 1. •Downstream effects of source separation and screening of MSW
- 2. •Sampling and analytical protocols
- 3. •Landfill gas
In addition to these groups a central secretariat based at Harwell (UK) has provided guidance, established and administered databases of contacts and produced a series of national reports.
This paper describes the achievements of the Activity and discusses work proposed for the future. 相似文献
3.
Johan M. Thevelein 《Yeast (Chichester, England)》1994,10(13):1753-1790
4.
将金属铜易与过氧化物发生氧化还原反应生成游离基的原理应用于厌氧胶,开发了针时金属零件表面微孔进行局部渗补的实用技术。在相关技术可靠性和工艺可行性得以论证的前提下。将局部渗补技术成功地应用于渗补发动机泄漏缸盖,减少了废品损失,取得了良好的经济效益。 相似文献
5.
6.
方晞 《建筑科学与工程学报》1994,(3)
叙述了用气浮地→厌氧塘→兼性塘处理造纸废水的试验与设计。经运行后测定,出水达到了天津市水污染物排放标准的要求。气浮池采用30%的回流比,提高了处理效率,每天可回收纸板原料8.4~10.8t。 相似文献
7.
Peng Dangcong Jin Qiting 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(1):89-93
The anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up-flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m?3 day?1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm3 per dm3 of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster-like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability. 相似文献
8.
9.
Luiza Ghila Thomas Aga Legy Andreas Frslev Mathisen Shadab Abadpour Joao A. Paulo Hanne Scholz Helge Rder Simona Chera 《International journal of molecular sciences》2021,22(7)
The past decade revealed that cell identity changes, such as dedifferentiation or transdifferentiation, accompany the insulin-producing β-cell decay in most diabetes conditions. Mapping and controlling the mechanisms governing these processes is, thus, extremely valuable for managing the disease progression. Extracellular glucose is known to influence cell identity by impacting the redox balance. Here, we use global proteomics and pathway analysis to map the response of differentiating human pancreatic progenitors to chronically increased in vitro glucose levels. We show that exogenous high glucose levels impact different protein subsets in a concentration-dependent manner. In contrast, regardless of concentration, glucose elicits an antipodal effect on the proteome landscape, inducing both beneficial and detrimental changes in regard to achieving the desired islet cell fingerprint. Furthermore, we identified that only a subgroup of these effects and pathways are regulated by changes in redox balance. Our study highlights a complex effect of exogenous glucose on differentiating pancreas progenitors characterized by a distinct proteome signature. 相似文献
10.
Bacterial communities associated with roots influence the health and nutrition of the host plant. However, the microbiome discrepancy are not well understood under different healthy conditions. Here, we tested the hypothesis that rhizosphere soil microbial diversity and function varies along a degeneration gradient of poplar, with a focus on plant growth promoting bacteria (PGPB) and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG (antibiotics resistance genes) annotation revealed that available potassium (AK) was correlated with microbial diversity and function. We proposed several microbes, Bradyrhizobium, Sphingomonas, Mesorhizobium, Nocardioides, Variovorax, Gemmatimonadetes, Rhizobacter, Pedosphaera, Candidatus Solibacter, Acidobacterium, and Phenylobacterium, as candidates to reflect the soil fertility and the plant health. The highest abundance of multidrug resistance genes and the four mainly microbial resistance mechanisms (antibiotic efflux, antibiotic target protection, antibiotic target alteration, and antibiotic target replacement) in healthy poplar rhizosphere, corroborated the relationship between soil fertility and microbial activity. This result suggested that healthy rhizosphere soil harbored microbes with a higher capacity and had more complex microbial interaction network to promote plant growing and reduce intracellular levels of antibiotics. Our findings suggested a correlation between the plant degeneration gradient and bacterial communities, and provided insight into the role of high-turnover microbial communities as well as potential PGPB as real-time indicators of forestry soil quality, and demonstrated the inner interaction contributed by the bacterial communities. 相似文献