全文获取类型
收费全文 | 14029篇 |
免费 | 1390篇 |
国内免费 | 770篇 |
专业分类
电工技术 | 907篇 |
综合类 | 1212篇 |
化学工业 | 2476篇 |
金属工艺 | 667篇 |
机械仪表 | 767篇 |
建筑科学 | 1111篇 |
矿业工程 | 394篇 |
能源动力 | 371篇 |
轻工业 | 1577篇 |
水利工程 | 322篇 |
石油天然气 | 678篇 |
武器工业 | 92篇 |
无线电 | 1477篇 |
一般工业技术 | 1480篇 |
冶金工业 | 597篇 |
原子能技术 | 243篇 |
自动化技术 | 1818篇 |
出版年
2024年 | 70篇 |
2023年 | 279篇 |
2022年 | 506篇 |
2021年 | 606篇 |
2020年 | 485篇 |
2019年 | 378篇 |
2018年 | 406篇 |
2017年 | 451篇 |
2016年 | 379篇 |
2015年 | 564篇 |
2014年 | 755篇 |
2013年 | 861篇 |
2012年 | 922篇 |
2011年 | 1039篇 |
2010年 | 928篇 |
2009年 | 932篇 |
2008年 | 881篇 |
2007年 | 825篇 |
2006年 | 840篇 |
2005年 | 780篇 |
2004年 | 531篇 |
2003年 | 358篇 |
2002年 | 434篇 |
2001年 | 358篇 |
2000年 | 325篇 |
1999年 | 255篇 |
1998年 | 186篇 |
1997年 | 158篇 |
1996年 | 146篇 |
1995年 | 114篇 |
1994年 | 103篇 |
1993年 | 68篇 |
1992年 | 51篇 |
1991年 | 47篇 |
1990年 | 30篇 |
1989年 | 27篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Weizeng Lv Xue He Haojuan Guo Haibin Lan Yanqing Jiao Le Li Yanhao Lian Zhiqiang Wang Zeyu Xin Yongzhe Ren Tongbao Lin 《International journal of molecular sciences》2022,23(14)
Excessive input of nitrogen fertilizer not only causes a great waste of resources but brings about a series of ecological and environmental problems. Although Small Auxin Up-regulated RNAs (SAURs) participate in diverse biological processes, the function of SAURs in the nitrogen starvation response has not been well-studied. Here, we identified 308 TaSAURs in wheat and divided them into 10 subfamilies. The promoter regions of most TaSAURs contain hormone responsive elements, and their expression levels change under the treatment of different hormones, such as IAA, MeJA, and ABA. Interestingly, overexpression of one of the TaSAUR family members, a nitrogen starvation responsive gene, TaSAUR66-5B, can promote the growth of Arabidopsis and wheat roots. In addition, overexpression of TaSAUR66-5B in Arabidopsis up-regulates the expression levels of auxin biosynthesis related genes, suggesting that overexpression TaSAUR66-5B may promote root growth by increasing the biosynthesis of auxin. Furthermore, overexpression of TaSAUR66-5B in wheat can increase the biomass and grain yields of transgenic plants, as well as the nitrogen concentration and accumulation of both shoots and grains, especially under low nitrogen conditions. This study provides important genomic information of the TaSAUR gene family and lays a foundation for elucidating the functions of TaSAURs in improving nitrogen utilization efficiency in wheat. 相似文献
43.
Renal inflammation is an initial pathological process during progressive renal injury regardless of the initial cause. Macrophage migration inhibitory factor (MIF) is a truly proinflammatory stress mediator that is highly expressed in a variety of both inflammatory cells and intrinsic kidney cells. MIF is released from the diseased kidney immediately upon stimulation to trigger renal inflammation by activating macrophages and T cells, and promoting the production of proinflammatory cytokines, chemokines, and stress molecules via signaling pathways involving the CD74/CD44 and chemokine receptors CXCR2, CXCR4, and CXCR7 signaling. In addition, MIF can function as a stress molecule to counter-regulate the immunosuppressive effect of glucocorticoid in renal inflammation. Given the critical position of MIF in the upstream inflammatory cascade, this review focuses on the regulatory role and molecular mechanisms of MIF in kidney diseases. The therapeutic potential of targeting MIF signaling to treat kidney diseases is also discussed. 相似文献
44.
45.
强烈的光照作为墨西哥一个十分突出的地域特征,对墨西哥的气候、文化乃至民众的生活习惯都产生了巨大的影响。墨西哥建筑师敏锐地捕捉到这一特征,融入自己的理解和想象,在光影与空间的交织、变化中呈现出丰富的情感色彩,使得建筑与人之间建立起直触心灵的对话。随着时代的变迁和文化的发展,建筑所要实现的功能、表达的情感在不断改变,而建筑师们对于光影的处理手段也趋于多元化,从而产生了越来越多极具特色的建筑形式。通过对墨西哥不同历史时期建筑的分析,来研究墨西哥建筑师运用光影塑造不同情感空间的多种手法和传承关系。 相似文献
46.
Peter I. Cowin Rong Lan Lei Zhang Christophe T.G. Petit Arno Kraft Shanwen Tao 《Materials Chemistry and Physics》2011
FeVO4 was synthesised by conventional solid state technique. Impedance measurements using a silver electrode were unsuccessful due to a solid state reaction between FeVO4 and Ag, forming α-AgVO3 and α-Fe2O3 at the interface. Impedance measurements, with a platinum electrode, reaffirmed that FeVO4 exhibits semiconductor behaviour in air. In a reducing atmosphere, 5% H2/Ar, high electronic conductivity, from 1 S cm−1 at 300 °C to 2 S cm−1 at 700 °C, was observed with an activation energy of 0.13(1) eV. X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry data determined that the change in electronic conductivity was due to the degradation of the material into FeV2O4 and α-Fe2O3. It is believed that the conduction was due to electron hopping between vanadium d-orbitals. Neither FeVO4 nor FeV2O4 are deemed suitable as anode materials for solid oxide fuel cells, due to redox instability. 相似文献
47.
48.
49.
震害调查表明,建筑结构的地震扭转效应将会加重结构的破坏,甚至造成建筑物倒塌。本文在总结国内外对结构平动-扭转耦联研究的基础上,提出了采用消能支撑减小结构扭转效应的分析计算方法。以单层非对称结构为例,较系统地分析了附加阻尼比、阻尼偏心率和偏心侧阻尼布置率等参数对扭转效应的控制效果,提出了阻尼支撑布置的原则,可用于指导减震结构设计。 相似文献
50.
在对邯郸传统村落与民居进行研究的基础上,发现了保存完整的天地庙,从文化的角度对其进行了分析,使我们对天地庙的有更深的理解。 相似文献