全文获取类型
收费全文 | 127530篇 |
免费 | 10888篇 |
国内免费 | 6041篇 |
专业分类
电工技术 | 7093篇 |
技术理论 | 8篇 |
综合类 | 10014篇 |
化学工业 | 20920篇 |
金属工艺 | 7049篇 |
机械仪表 | 8210篇 |
建筑科学 | 8540篇 |
矿业工程 | 3163篇 |
能源动力 | 3837篇 |
轻工业 | 9966篇 |
水利工程 | 2239篇 |
石油天然气 | 5783篇 |
武器工业 | 988篇 |
无线电 | 15548篇 |
一般工业技术 | 15565篇 |
冶金工业 | 5884篇 |
原子能技术 | 1749篇 |
自动化技术 | 17903篇 |
出版年
2024年 | 327篇 |
2023年 | 1650篇 |
2022年 | 2698篇 |
2021年 | 4346篇 |
2020年 | 3338篇 |
2019年 | 2929篇 |
2018年 | 3308篇 |
2017年 | 3692篇 |
2016年 | 3542篇 |
2015年 | 4680篇 |
2014年 | 6268篇 |
2013年 | 7633篇 |
2012年 | 8623篇 |
2011年 | 9391篇 |
2010年 | 8370篇 |
2009年 | 8216篇 |
2008年 | 8142篇 |
2007年 | 7693篇 |
2006年 | 7443篇 |
2005年 | 6303篇 |
2004年 | 4965篇 |
2003年 | 4375篇 |
2002年 | 4936篇 |
2001年 | 4263篇 |
2000年 | 3340篇 |
1999年 | 2762篇 |
1998年 | 2132篇 |
1997年 | 1774篇 |
1996年 | 1598篇 |
1995年 | 1310篇 |
1994年 | 1012篇 |
1993年 | 710篇 |
1992年 | 581篇 |
1991年 | 433篇 |
1990年 | 376篇 |
1989年 | 275篇 |
1988年 | 243篇 |
1987年 | 158篇 |
1986年 | 115篇 |
1985年 | 95篇 |
1984年 | 69篇 |
1983年 | 65篇 |
1982年 | 52篇 |
1981年 | 40篇 |
1980年 | 28篇 |
1979年 | 24篇 |
1978年 | 11篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
Baofeng Hou Hong He Ruixiu Jia Meilong Fu Yanbin Cao Shaoqun He Liwen Luo Youqing Huang 《应用聚合物科学杂志》2019,136(10):47161
The synthesis and performance of a novel temperature-tolerant foamed resin for enhanced oil recovery were investigated using various methods, including infrared, NMR, scanning electron microscopy (SEM), and displacement experiments. Polycondensation of furfuryl alcohol prepolymers was confirmed by the infrared and NMR results. The poor temperature tolerance of furfuryl alcohol prepolymers after gelation at high temperatures is mainly due to the fracture of furan rings. The addition of ester additives is an effective method of increasing the temperature tolerance of the prepared foamed resins and can effectively reduce the weight-loss rate of the polycondensation products. The SEM results show that the skeleton structure of the foamed resin remains intact after high-temperature treatment. Thus, the novel plugging agent system has excellent thermal stability and still has a high strength (>0.8 MPa) after high-temperature aging treatment for 40 days, giving the prepared foamed resin a good plugging performance (plugging rate > 91%) at 250 °C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47161. 相似文献
42.
The mammalian cell cycle is important in controlling normal cell proliferation and the development of various diseases. Cell cycle checkpoints are well regulated by both activators and inhibitors to avoid cell growth disorder and cancerogenesis. Cyclin dependent kinase 20 (CDK20) and p21Cip1/Waf1 are widely recognized as key regulators of cell cycle checkpoints controlling cell proliferation/growth and involving in developing multiple cancers. Emerging evidence demonstrates that these two cell cycle regulators also play an essential role in promoting cell survival independent of the cell cycle, particularly in those cells with a limited capability of proliferation, such as cardiomyocytes. These findings bring new insights into understanding cytoprotection in these tissues. Here, we summarize the new progress of the studies on these two molecules in regulating cell cycle/growth, and their new roles in cell survival by inhibiting various cell death mechanisms. We also outline their potential implications in cancerogenesis and protection in heart diseases. This information renews the knowledge in molecular natures and cellular functions of these regulators, leading to a better understanding of the pathogenesis of the associated diseases and the discovery of new therapeutic strategies. 相似文献
43.
44.
45.
Harshavardhan Mohan Jeong-Muk Lim Se-Won Lee Min Cho Yool-Jin Park Kamala-Kannan Seralathan Byung-Taek Oh 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2020,95(1):297-307
The cover image is based on the Research Article V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .
46.
47.
48.
Process object is the instance of process. Vertexes and edges are in the graph of process object. There are different types of the object itself and the associations between object. For the large-scale data, there are many changes reflected. Recently, how to find appropriate real-time data for process object becomes a hot research topic. Data sampling is a kind of finding c hanges o f p rocess o bjects. There i s r equirements f or s ampling to be adaptive to underlying distribution of data stream. In this paper, we have proposed a adaptive data sampling mechanism to find a ppropriate d ata t o m odeling. F irst o f all, we use concept drift to make the partition of the life cycle of process object. Then, entity community detection is proposed to find changes. Finally, we propose stream-based real-time optimization of data sampling. Contributions of this paper are concept drift, community detection, and stream-based real-time computing. Experiments show the effectiveness and feasibility of our proposed adaptive data sampling mechanism for process object. 相似文献
49.
Wei-Fei Hu Shuo Chen Hong-Chao Hao Hong Jiang 《American Institute of Chemical Engineers》2022,68(11):e17879
Herein, we propose a novel method to enhance the photoreactivity of an MOF catalyst by grafting isocyanate bonds ( NCO) and sulfhydryl-complexed copper ( SCu) onto ZIF-8 (NIF-SCu). The grafting process intercalated interlayer bands between the conduction and valence bands of ZIF-8, thereby providing a “ladder” for facile electron transition. The extreme improvement in the photoreactivity of NIF-SCu could be attributed to the enhancement in light responses in the range of 350–450 nm by NCO groups and the widening of the visible light range of the MOF by SCu groups. The formation of staggered energy levels in NIF-SCu could also narrow the band gap, lower the resistance, and facilitate the transfer of photogenerated carriers, thereby generating electrons with strong reduction potential in the SCu conduction band. This study provides a new strategy for improving or even endowing the photoactivity of environmental functional materials with wide bandgaps. 相似文献
50.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献