全文获取类型
收费全文 | 11584篇 |
免费 | 1155篇 |
国内免费 | 379篇 |
专业分类
电工技术 | 396篇 |
技术理论 | 3篇 |
综合类 | 870篇 |
化学工业 | 1867篇 |
金属工艺 | 242篇 |
机械仪表 | 493篇 |
建筑科学 | 3895篇 |
矿业工程 | 465篇 |
能源动力 | 296篇 |
轻工业 | 1660篇 |
水利工程 | 226篇 |
石油天然气 | 127篇 |
武器工业 | 32篇 |
无线电 | 602篇 |
一般工业技术 | 801篇 |
冶金工业 | 286篇 |
原子能技术 | 9篇 |
自动化技术 | 848篇 |
出版年
2024年 | 79篇 |
2023年 | 280篇 |
2022年 | 406篇 |
2021年 | 510篇 |
2020年 | 550篇 |
2019年 | 392篇 |
2018年 | 338篇 |
2017年 | 394篇 |
2016年 | 444篇 |
2015年 | 448篇 |
2014年 | 1053篇 |
2013年 | 886篇 |
2012年 | 969篇 |
2011年 | 883篇 |
2010年 | 707篇 |
2009年 | 658篇 |
2008年 | 522篇 |
2007年 | 673篇 |
2006年 | 605篇 |
2005年 | 519篇 |
2004年 | 364篇 |
2003年 | 331篇 |
2002年 | 309篇 |
2001年 | 215篇 |
2000年 | 189篇 |
1999年 | 122篇 |
1998年 | 67篇 |
1997年 | 42篇 |
1996年 | 35篇 |
1995年 | 23篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas 总被引:1,自引:0,他引:1
Dr. P. Göbel Prof. Dr. W.G. Coldewey Dr.-Ing. C. Dierkes Dipl.-Math. H. Kories Dr. J. Meßer Dr.-Ing. E. Meißner 《Grundwasser》2007,12(3):189-200
Ohne Zusammenfassung
Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas
相似文献
42.
43.
介绍自行车产品的研发设计,提出利用产品数据管理系统(PDM)进行绿色自行车产品设计的方案。 相似文献
44.
45.
The paper suggests a new methodology for secure cyber–physical systems design. The proposed methodology consists of two main cycles. The main goal of the first cycle is in design of the system model, while the second one is about development of the system prototype. The key idea of the methodology is in providing of the most rational solutions that are improving the security of cyber–physical systems. Such solutions are called alternatives and built according to functional requirements and non-functional limitations to the system. Each cycle of the methodology consists of the verification process and seven stages that are associated with the used cyber–physical system model. The objective of the verification process is in checking of constructed models and prototypes in terms of their correctness and compatibility. The model represents cyber–physical systems as sets of building blocks with network between them, takes elements internal structure into account and allows direct and reverse transformations. The novelty of the suggested methodology is in the combination of design, development and verification techniques within a single approach. To provide an example of the design methodology application, in this paper it is used to improve the semi-natural model of the railway infrastructure. 相似文献
46.
47.
为了促进风电消纳以及提高电力系统的经济性,构建基于绿色证书交易机制的含风电场电力系统多目标动态环境经济调度(DEED)模型,提出一种基于反向学习混沌搜索的OLCS-MOEA/D算法的DEED调度求解方法。首先,采用广义反向学习初始化种群提高种群多样性,并引入基于Logistic映射的混沌搜索算法以增强算法局部搜索能力。然后,为了验证算法的性能,采用标准测试函数F1—F7进行测试,同时将该算法对模型进行求解,获得了比其他算法范围更广和分布均匀的Pareto解集前沿。最后,对基于绿色证书交易机制的动态环境经济调度与传统动态环境经济调度进行结果对比分析,通过仿真算例验证该模型和算法的有效性和优越性。 相似文献
48.
Wanting Li Zixuan Huang Rui Cai Wan Yang Huawei He Yejing Wang 《International journal of molecular sciences》2021,22(1)
Silver-based hybrid nanomaterials are receiving increasing attention as potential alternatives for traditional antimicrobial agents. Here, we proposed a simple and eco-friendly strategy to efficiently assemble zinc oxide nanoparticles (ZnO) and silver nanoparticles (AgNPs) on sericin-agarose composite film to impart superior antimicrobial activity. Based on a layer-by-layer self-assembly strategy, AgNPs and ZnO were immobilized on sericin-agarose films using the adhesion property of polydopamine. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction spectroscopy were used to show the morphology of AgNPs and ZnO on the surface of the composite film and analyze the composition and structure of AgNPs and ZnO, respectively. Water contact angle, swelling ratio, and mechanical property were determined to characterize the hydrophilicity, water absorption ability, and mechanical properties of the composite films. In addition, the antibacterial activity of the composite film was evaluated against Gram-positive and Gram-negative bacteria. The results showed that the composite film not only has desirable hydrophilicity, high water absorption ability, and favorable mechanical properties but also exhibits excellent antimicrobial activity against both Gram-positive and Gram-negative bacteria. It has shown great potential as a novel antimicrobial biomaterial for wound dressing, artificial skin, and tissue engineering. 相似文献
49.
Thermal sprayed aluminum and zinc provide long-term (> 20 years to first maintenance) corrosion control coatings. However,
this application is usually more expensive than painting or galvanizing if thermal spraying (metallizing) is not integrated
into the design and fabrication phases of new construction and repair projects. Aluminum and zinc metallized coatings are
tough enough to withstand fabrication, transportation, and assembly operations. The improved capabilities and productivity
of metallizing equipment for aluminum and zinc spraying are a major factor in their current cost competitiveness. The net
result is that the cost difference between metallizing, paint, and galvanizing is getting closer every day. Even though the
initial application cost of metallizing may be higher, the life cycle cost (LCC) and average equivalent annual costs (AEAC)
are lower than paint coating systems. Metallizing LCCs, when properly engineered into the construction schedule, are equal
to or less than paint coating LCCs. This article summarizes some metallizing considerations for installing improved corrosion
control coating systems in new construction and in maintenance and repair of infrastructure.
Editor’s Note: The following constants have been used to convert between English and Metric dimensions: 1ft2-0.0929 m2; 1lb/ft2-4.89 kg/m2; 1 mil=0.025mm.
Presented at the 5th National Thermal Spray Conference (NTSC-93), Infrastructure Maintenance and Repair Session, 10 June 1993,
Anaheim, CA. 相似文献
50.
Amr Fouda Mohamed A. Awad Ahmed M. Eid Ebrahim Saied Mohammed G. Barghoth Mohammed F. Hamza Mohamed F. Awad Salah Abdelbary Saad El-Din Hassan 《International journal of molecular sciences》2021,22(10)
The discovery of eco-friendly, rapid, and cost-effective compounds to control diseases caused by microbes and insects are the main challenges. Herein, the magnesium oxide nanoparticles (MgO-NPs) are successfully fabricated by harnessing the metabolites secreted by Penicillium chrysogenum. The fabricated MgO-NPs were characterized using UV-Vis, XRD, TEM, DLS, EDX, FT-IR, and XPS analyses. Data showed the successful formation of crystallographic, spherical, well-dispersed MgO-NPs with sizes of 7–40 nm at a maximum wavelength of 250 nm. The EDX analysis confirms the presence of Mg and O ions as the main components with weight percentages of 13.62% and 7.76%, respectively. The activity of MgO-NPs as an antimicrobial agent was investigated against pathogens Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans, and exhibited zone of inhibitions of 12.0 ± 0.0, 12.7 ± 0.9, 23.3 ± 0.8, 17.7 ± 1.6, and 14.7 ± 0.6 mm respectively, at 200 µg mL−1. The activity is decreased by decreasing the MgO-NPs concentration. The biogenic MgO-NPs exhibit high efficacy against different larvae instar and pupa of Anopheles stephensi, with LC50 values of 12.5–15.5 ppm for I–IV larvae instar and 16.5 ppm for the pupa. Additionally, 5 mg/cm2 of MgO-NPs showed the highest protection percentages against adults of Anopheles stephensi, with values of 100% for 150 min and 67.6% ± 1.4% for 210 min. 相似文献