全文获取类型
收费全文 | 7210篇 |
免费 | 1007篇 |
国内免费 | 40篇 |
专业分类
电工技术 | 79篇 |
技术理论 | 2篇 |
综合类 | 529篇 |
化学工业 | 107篇 |
金属工艺 | 2篇 |
机械仪表 | 8篇 |
建筑科学 | 6823篇 |
矿业工程 | 87篇 |
能源动力 | 19篇 |
轻工业 | 16篇 |
水利工程 | 213篇 |
石油天然气 | 4篇 |
武器工业 | 2篇 |
无线电 | 14篇 |
一般工业技术 | 97篇 |
冶金工业 | 39篇 |
自动化技术 | 216篇 |
出版年
2024年 | 149篇 |
2023年 | 367篇 |
2022年 | 475篇 |
2021年 | 511篇 |
2020年 | 556篇 |
2019年 | 440篇 |
2018年 | 193篇 |
2017年 | 145篇 |
2016年 | 100篇 |
2015年 | 153篇 |
2014年 | 684篇 |
2013年 | 394篇 |
2012年 | 527篇 |
2011年 | 593篇 |
2010年 | 500篇 |
2009年 | 415篇 |
2008年 | 418篇 |
2007年 | 403篇 |
2006年 | 323篇 |
2005年 | 215篇 |
2004年 | 145篇 |
2003年 | 130篇 |
2002年 | 112篇 |
2001年 | 102篇 |
2000年 | 44篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 27篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 4篇 |
排序方式: 共有8257条查询结果,搜索用时 15 毫秒
111.
利用各种自然因素创造良好的地下空间环境 总被引:1,自引:0,他引:1
提出了为创造良好的地下空间环境,必须要利用各种自然因素:天然光线、外部景观、绿色植物及水体,并将其引入地下的设想;指出了它们对地下空间的生态环境所引起的积极作用,特别是对人的心理产生的良好影响,并探讨了这几种自然因素在地下空间中的运用手法。 相似文献
112.
Taninaka A Hirano Y Takeuchi O Shigekawa H 《International journal of molecular sciences》2012,13(1):453-465
Dynamic force spectroscopy (DFS) makes it possible to investigate specific interactions between two molecules such as ligand-receptor pairs at the single-molecule level. In the DFS method based on the Bell-Evans model, the unbinding force applied to a molecular bond is increased at a constant rate, and the force required to rupture the molecular bond is measured. By analyzing the relationship between the modal rupture force and the logarithm of the loading rate, microscopic potential barrier landscapes and the lifetimes of bonds can be obtained. However, the results obtained, for example, in the case of streptavidin/biotin complexes, have differed among previous studies and some results have been inconsistent with theoretical predictions. In this study, using an atomic force microscopy technique that enables the precise analysis of molecular interactions on the basis of DFS, we investigated the effect of the sampling rate on DFS analysis. The shape of rupture force histograms, for example, was significantly deformed at a sampling rate of 1 kHz in comparison with that of histograms obtained at 100 kHz, indicating the fundamental importance of ensuring suitable experimental conditions for further advances in the DFS method. 相似文献
113.
通过正交试验研究了工艺参数对铸铜层性能的影响。结果表明:电铸铜工艺在景观雕塑制作领域有其独特优势。依据景观雕塑使用条件,在保证铸铜层硬度的前提下,确定了硫酸铜240g/L、硫酸60g/L、电流密度4A/dm~2、温度20℃为最佳的电铸铜工艺条件;在保证铸铜层拉伸强度的前提下,确定了硫酸铜220g/L、硫酸70g/L、电流密度6A/dm~2、温度20℃或30℃为最佳的电铸铜工艺条件;控制电流密度在6A/dm~2左右,铸铜层的硬度与拉伸强度良好。 相似文献
114.
以明初(洪武、建文)时期景德镇青花山水元素的产生原因,笔墨特征为研究线索,结合图片资料,分析了这一时期青花山水元素的艺术特证,对明代青花山水纹饰艺术特征演变规律的全面研究进行了有益的补充,也为现代陶瓷山水画的发展与创新提供了有益的启示。 相似文献
115.
116.
117.
王琼 《安徽建筑大学学报》2017,25(4)
随着城市日新月异的发展,城市建设与服务功能不断完善,接踵而至的城市问题也应受到人们重视。而住区是人在工作、学习、生活中所占较大比重的场所,因此,通过对住区中"陌生人"的交往现状及其共处的景观环境进行研究,结合调研分析,试图探索增进"住区陌生人"交往的新交往共享环境设计的理论依托,提出创新空间,设计具有本土特色和更完备的人性化景观,更新交往方式,构建住区景观环境中的情感空间,期望城市住区向更宜居、更和谐舒适的方向发展。 相似文献
118.
Zhi-Bi Zhang Yuan-Ling Xia Guang-Heng Dong Yun-Xin Fu Shu-Qun Liu 《International journal of molecular sciences》2021,22(4)
Cold-adapted enzymes feature a lower thermostability and higher catalytic activity compared to their warm-active homologues, which are considered as a consequence of increased flexibility of their molecular structures. The complexity of the (thermo)stability-flexibility-activity relationship makes it difficult to define the strategies and formulate a general theory for enzyme cold adaptation. Here, the psychrophilic serine hydroxymethyltransferase (pSHMT) from Psychromonas ingrahamii and its mesophilic counterpart, mSHMT from Escherichia coli, were subjected to μs-scale multiple-replica molecular dynamics (MD) simulations to explore the cold-adaptation mechanism of the dimeric SHMT. The comparative analyses of MD trajectories reveal that pSHMT exhibits larger structural fluctuations and inter-monomer positional movements, a higher global flexibility, and considerably enhanced local flexibility involving the surface loops and active sites. The largest-amplitude motion mode of pSHMT describes the trends of inter-monomer dissociation and enlargement of the active-site cavity, whereas that of mSHMT characterizes the opposite trends. Based on the comparison of the calculated structural parameters and constructed free energy landscapes (FELs) between the two enzymes, we discuss in-depth the physicochemical principles underlying the stability-flexibility-activity relationships and conclude that (i) pSHMT adopts the global-flexibility mechanism to adapt to the cold environment and, (ii) optimizing the protein-solvent interactions and loosening the inter-monomer association are the main strategies for pSHMT to enhance its flexibility. 相似文献
119.
120.
An evaluation model for the rationality of the landscape design of urban rivers was established with the analytic hierarchy process (AHP) method so as to provide a foundation for updating the landscape design of urban rivers. The evaluation system was divided into four layers, including the target layer, the comprehensive layer, the element layer, and the index layer. Each layer was made of different indices. The evaluation standards for each index were also given in this paper. This evaluation model was proved tenable through its application to the landscape design rationality evaluation of the Weihe River in Xinxiang City of Henan Province. The results show that the water quality, space, activity, facility, community, width of vegetation, sense of beauty and water content are among the most influential factors and should be considered the main basis for evaluating the rationality of the landscape design of urban rivers. 相似文献