全文获取类型
收费全文 | 26575篇 |
免费 | 2936篇 |
国内免费 | 2130篇 |
专业分类
电工技术 | 3694篇 |
技术理论 | 3篇 |
综合类 | 2778篇 |
化学工业 | 2708篇 |
金属工艺 | 1572篇 |
机械仪表 | 2034篇 |
建筑科学 | 1284篇 |
矿业工程 | 557篇 |
能源动力 | 1564篇 |
轻工业 | 424篇 |
水利工程 | 491篇 |
石油天然气 | 990篇 |
武器工业 | 62篇 |
无线电 | 3614篇 |
一般工业技术 | 2605篇 |
冶金工业 | 258篇 |
原子能技术 | 228篇 |
自动化技术 | 6775篇 |
出版年
2024年 | 31篇 |
2023年 | 639篇 |
2022年 | 803篇 |
2021年 | 922篇 |
2020年 | 1035篇 |
2019年 | 1146篇 |
2018年 | 456篇 |
2017年 | 665篇 |
2016年 | 699篇 |
2015年 | 678篇 |
2014年 | 1551篇 |
2013年 | 1931篇 |
2012年 | 2924篇 |
2011年 | 2992篇 |
2010年 | 2198篇 |
2009年 | 2544篇 |
2008年 | 1653篇 |
2007年 | 2942篇 |
2006年 | 2646篇 |
2005年 | 1084篇 |
2004年 | 444篇 |
2003年 | 273篇 |
2002年 | 218篇 |
2001年 | 189篇 |
2000年 | 268篇 |
1999年 | 167篇 |
1998年 | 171篇 |
1997年 | 99篇 |
1996年 | 60篇 |
1995年 | 49篇 |
1994年 | 37篇 |
1993年 | 55篇 |
1992年 | 41篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1986年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1976年 | 1篇 |
1959年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Soils and Foundations》2022,62(3):101150
The circular helicoid pile (CH pile) is a new type of special-shaped pile that has been developed in Japan and South Korea in the past decade and has been widely used in the fields of construction, transportation, natural energy and agriculture due to its excellent compressive and pullout bearing performances. Consequently, this new type of pile has good engineering application prospects. However, as an innovative engineering structure, the CH pile is not widely known by geotechnical engineers worldwide. The geometric structure of the CH pile is similar to a circular helicoid in differential geometry. Therefore, the pile-soil interaction problem cannot be reduced to a plane strain problem or an axisymmetric problem in theoretical research. In view of this, dry silica sand was used as the model foundation in this study, and a model test device and method that can effectively reflect the installation process and loading-bearing service state of CH piles were developed. Under different installation methods, pile structures and foundation soil conditions, 90 model tests were carried out to evaluate the engineering performances of CH piles during the whole process of installation and bearing, including the installation performances during the installation process, the compressive bearing performances under axial compressive loading and the pullout bearing performances under axial pullout loading. Compared with steel sheet piles and steel pipe piles, CH piles have better engineering performance and more economic benefits from the aspects of installation, construction, recycling, timeliness of engineering application, and the relative relationship between bearing capacity and pile mass. 相似文献
2.
The new mode for managing construction projects with information technology (IT) has attracted worldwide attention because it can help managers and workers perform tasks and bring potential benefits, such as high-quality products and accident-free production, effectively. However, the application of IT in site have not achieved expected results because it is faced with many constraints caused by internal factors from enterprises and projects and external factors from the government and environment. Although many relevant studies have discussed the constraints of implementing different IT and devices in the construction industry or site, few articles have specifically focused on identifying and analyzing the indicator system. In this work, we took China as the background, scientifically identified 23 influential factors that affect the implementation of IT in construction management through literature review and expert interviews. Subsequently, questionnaires were issued, and Delphi method was used to obtain empirical data that aimed at four different management fields. Then, an efficient and convenient method called DEMATEL was used to deal with these data. Afterward, the factors were divided into four categories, namely, core, diving, independent, and impact factors. Finally, the similarities and differences of the analysis results from the four fields were compared, and the key factors were identified. Results show that the cross-domain talent ability, concept and value cognition, and organization structure are core factors in all management fields that should be managed first along with the IT innovation ability in the enterprise. The formulation of technical standards and related device and training input are also critical in specific fields. Strategic planning plays a role in macro control and promotion. Data management and application, platform construction, solution, and collaboration have direct impacts on information management. The research results provide suggestions not only for the government to formulate effective policies for IT application and promotion in construction industry, but also for enterprises to take measures in improving management efficiency in the construction site and realizing its substantial benefits. 相似文献
3.
环路水封清除(LSC)是压水堆冷管段小破口失水事故(SBLOCA)的典型事故特征之一。为确定LSC现象的物理模型影响,探究准确复现LSC现象的物理模型设置,从LSC现象物理机理的角度,对影响LSC的主要物理模型进行梳理和分析。结合LOBI台架SBLCOA系列实验,对LSC现象物理机理、物理模型影响进行模拟和验证。结果表明,在对影响LSC现象的物理模型进行合理设置后,RELAP5程序模型能较好地复现LOBI台架实验工况中的LSC现象,验证了LSC现象物理模型影响及模型设置的合理性。 相似文献
4.
Knowledge and Information Systems - Crowdsourcing systems provide an efficient way to collect labeled data by employing non-expert crowd workers. In practice, each instance obtains a multiple noisy... 相似文献
5.
6.
Li Guangyu Jiang Wenming Guan Feng Zhu Junwen Yu Yang Fan Zitian 《Metallurgical and Materials Transactions A》2022,53(10):3520-3527
The metallurgical bonding of Mg/Al bimetal by liquid–liquid compound casting was realized via co-deposition Cu–Ni alloy coating. The metallurgical layer of the Mg/Al bimetal consisted of Cu solid solution, Cu2Mg and (Al0.7Cu1.3) Mg, Mg solid solution, Al3Ni2, and Mg2Cu. Vickers hardness of the interface was between 149.9 and 209 HV, which was significantly lower than those of Al–Mg intermetallic compounds. The formation mechanism of the interface was attributed to interdiffusion among AZ91D, A356, and Cu–Ni alloy coating.
相似文献7.
Luo Manlelan Sliva Andrey P. Hu Renzhi Goncharov Aleksei L. Karpovich Dragunov Viktor Trushnikov Dmitriy N. Pang Shengyong 《Metallurgical and Materials Transactions A》2022,53(9):3369-3380
Metallurgical and Materials Transactions A - Low-frequency scanning electron beam welding (SEBW) is recently recognized as a possible control method for preventing the top concavity behavior in... 相似文献
8.
Neural Computing and Applications - A new iterative method based on the event-triggered strategy for finding a solution to a mixed equilibrium problem (MEP) is introduced in this paper. The target... 相似文献
9.
Li Jingchang Cao Longchao Hu Jiexiang Sheng Minhua Zhou Qi Jin Peng 《Journal of Intelligent Manufacturing》2022,33(3):687-702
Journal of Intelligent Manufacturing - As a rapid developing additive manufacturing (AM) technology, selective laser melting (SLM) provides a promising way for intelligent manufacturing. The SLM... 相似文献
10.
当海量数据请求访问异构内存系统时,异构内存页在动态随机存储器(dynamic random access memory, DRAM)和非易失性存储器(non-volatile memory, NVM)之间进行频繁的往返迁移.然而,应用于传统内存页的迁移策略难以适应内存页"冷""热"度的快速动态变化,这使得从DRAM迁移至NVM的"冷"页面可能在短时间内变"热"从而产生大量冗余的迁移操作.当前的相关研究都仅着眼于正在执行迁移的页面而忽视了等待迁移和完成迁移的页面,且判断"冷""热"程度的标准不一,使得冗余的迁移大量产生.因此,提出了一个基于DRAM牺牲Cache的异构内存页迁移机制(VC-HMM),使用非易失性存储器中工艺较为成熟的相变存储器(phase change memory, PCM),通过在DRAM和PCM之间增加一个由DRAM构成的小容量牺牲Cache将系统主存DRAM中变"冷"的页面迁移到牺牲Cache中,以避免主存页面在短时间内再次变"热"而造成的冗余迁移.同时,还使得迁回PCM的部分页面不需要写回,减少PCM存储单元的写入操作次数,延长PCM的使用寿命.另外,对于不同的工作负载,VC-HMM可以自适应设置迁移操作的参数,增加迁移的合理性.实验结果表明:与其他迁移策略(CoinMigrator, MQRA,THMigrator)相比,VC-HMM平均减少了至少62.97%的PCM写操作次数、22.72%的平均访问时延、38.37%的重复迁移操作以及3.40%的系统能耗. 相似文献