全文获取类型
收费全文 | 253220篇 |
免费 | 4497篇 |
国内免费 | 1049篇 |
专业分类
电工技术 | 4360篇 |
综合类 | 212篇 |
化学工业 | 37552篇 |
金属工艺 | 8269篇 |
机械仪表 | 7286篇 |
建筑科学 | 6936篇 |
矿业工程 | 543篇 |
能源动力 | 7281篇 |
轻工业 | 28701篇 |
水利工程 | 2126篇 |
石油天然气 | 1852篇 |
武器工业 | 5篇 |
无线电 | 33561篇 |
一般工业技术 | 46553篇 |
冶金工业 | 46546篇 |
原子能技术 | 3375篇 |
自动化技术 | 23608篇 |
出版年
2021年 | 1894篇 |
2020年 | 1427篇 |
2019年 | 1743篇 |
2018年 | 2655篇 |
2017年 | 2655篇 |
2016年 | 2967篇 |
2015年 | 2257篇 |
2014年 | 3766篇 |
2013年 | 12078篇 |
2012年 | 6891篇 |
2011年 | 9820篇 |
2010年 | 7564篇 |
2009年 | 8485篇 |
2008年 | 9010篇 |
2007年 | 9014篇 |
2006年 | 8348篇 |
2005年 | 7532篇 |
2004年 | 7236篇 |
2003年 | 7106篇 |
2002年 | 6610篇 |
2001年 | 7034篇 |
2000年 | 6330篇 |
1999年 | 6833篇 |
1998年 | 16399篇 |
1997年 | 11381篇 |
1996年 | 8590篇 |
1995年 | 6549篇 |
1994年 | 5712篇 |
1993年 | 5569篇 |
1992年 | 3996篇 |
1991年 | 3777篇 |
1990年 | 3548篇 |
1989年 | 3370篇 |
1988年 | 3277篇 |
1987年 | 2590篇 |
1986年 | 2490篇 |
1985年 | 3157篇 |
1984年 | 2797篇 |
1983年 | 2561篇 |
1982年 | 2345篇 |
1981年 | 2392篇 |
1980年 | 2204篇 |
1979年 | 2050篇 |
1978年 | 1880篇 |
1977年 | 2178篇 |
1976年 | 2729篇 |
1975年 | 1587篇 |
1974年 | 1490篇 |
1973年 | 1559篇 |
1972年 | 1144篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
57.
58.
Chinh Ngo Radhika Mehta Kanchan Aggarwal Audrey G. Fikes Dr. Ines C. Santos Dr. Sylvester M. Greer Prof. Dr. Emily L. Que 《Chembiochem : a European journal of chemical biology》2019,20(8):1003-1007
One-third of all proteins are estimated to require metals for structural stability and/or catalytic activity. Desthiobiotin probes containing metal binding groups can be used to capture metalloproteins with exposed active-site metals under mild conditions so as to prevent changes in metallation state. The proof-of-concept was demonstrated with carbonic anhydrase (CA), an open active site, Zn2+-containing protein. CA was targeted by using sulfonamide derivatives. Linkers of various lengths and structures were screened to determine the optimal structure for capture of the native protein. The optimized probes could selectively pull down CA from red blood cell lysate and other protein mixtures. Pull-down of differently metallated CAs was also investigated. 相似文献
59.
Jagadeesh Babu Sriramoju Murthy Muniyappa Navya Rani Marilingaiah Chetana Sabbanahalli Manjunath Shetty Ravi Mudike Chitrabanu C.P Prasanna D. Shivaramu Nagaraju G Kanchugarakoppal S. Rangappa Ananda Kumar C.S Dinesh Rangappa 《Ceramics International》2021,47(7):10314-10321
Application of brown titanium dioxide (TiO2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO2-x nanoparticles with g-C3N4, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO2-x nanocomposite with high rate constants of 0.075 min?1, 0.083 min?1 and 0.093 min?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e?)/hole (h+) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO2-x is carried out. 相似文献
60.
P. Carrasqueira H. Rocha J. M. Dias T. Ventura B. C. Ferreira M. C. Lopes 《International Transactions in Operational Research》2023,30(1):206-223
Radiation therapy is a technology-driven cancer treatment modality that has experienced significant advances over the last decades, due to multidisciplinary contributions that include engineering and computing. Recent technological developments allow the use of noncoplanar volumetric modulated arc therapy (VMAT), one of the most recent photon treatment techniques, in clinical practice. In this work, an automated noncoplanar arc trajectory optimization framework designed in two modular phases is presented. First, a noncoplanar beam angle optimization algorithm is used to obtain a set of noncoplanar irradiation directions. Then, anchored in these directions, an optimization strategy is proposed to compute an optimal arc trajectory. The computational experiments considered a pool of twelve difficult head-and-neck tumor cases. It was possible to observe that, for some of these cases, the optimized noncoplanar arc trajectories led to significant treatment planning quality improvements, when compared with coplanar VMAT treatment plans. Although these experiments were done in a research environment treatment planning software (matRad), the conclusions can be of interest for a clinical setting: automated procedures can simplify the current treatment workflow, produce high-quality treatment plans, making better use of human resources and allowing for unbiased comparisons between different treatment techniques. 相似文献