全文获取类型
收费全文 | 224968篇 |
免费 | 18638篇 |
国内免费 | 6205篇 |
专业分类
电工技术 | 14538篇 |
技术理论 | 22篇 |
综合类 | 13827篇 |
化学工业 | 35376篇 |
金属工艺 | 12414篇 |
机械仪表 | 14017篇 |
建筑科学 | 16434篇 |
矿业工程 | 6666篇 |
能源动力 | 6751篇 |
轻工业 | 15675篇 |
水利工程 | 3975篇 |
石油天然气 | 12567篇 |
武器工业 | 1670篇 |
无线电 | 27251篇 |
一般工业技术 | 27301篇 |
冶金工业 | 10164篇 |
原子能技术 | 2632篇 |
自动化技术 | 28531篇 |
出版年
2025年 | 926篇 |
2024年 | 5729篇 |
2023年 | 5242篇 |
2022年 | 7916篇 |
2021年 | 10456篇 |
2020年 | 8729篇 |
2019年 | 7087篇 |
2018年 | 7089篇 |
2017年 | 7788篇 |
2016年 | 7125篇 |
2015年 | 9166篇 |
2014年 | 11250篇 |
2013年 | 13103篇 |
2012年 | 14137篇 |
2011年 | 14916篇 |
2010年 | 12692篇 |
2009年 | 12075篇 |
2008年 | 11583篇 |
2007年 | 10637篇 |
2006年 | 10839篇 |
2005年 | 9236篇 |
2004年 | 6142篇 |
2003年 | 5299篇 |
2002年 | 4783篇 |
2001年 | 4292篇 |
2000年 | 4236篇 |
1999年 | 4918篇 |
1998年 | 4071篇 |
1997年 | 3462篇 |
1996年 | 3204篇 |
1995年 | 2627篇 |
1994年 | 2112篇 |
1993年 | 1538篇 |
1992年 | 1274篇 |
1991年 | 931篇 |
1990年 | 696篇 |
1989年 | 584篇 |
1988年 | 450篇 |
1987年 | 310篇 |
1986年 | 238篇 |
1985年 | 166篇 |
1984年 | 143篇 |
1983年 | 110篇 |
1982年 | 114篇 |
1981年 | 77篇 |
1980年 | 78篇 |
1979年 | 35篇 |
1978年 | 31篇 |
1977年 | 31篇 |
1976年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Zan Li Yang Li Wei Qin Xiaohong Wu 《Journal of Materials Science: Materials in Electronics》2016,27(7):6673-6680
AZO powders were sensitized through chemisorption method by octa-iso-pentyloxy phthalocyanine lead and characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results showed that after sensitization process AZO photo physical properties improved greatly in visible regions. Photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution and the pseudo first order model was used to obtain kinetic information of the photocatalytic degradation. The results indicated that photocatalytic activities of PbPc(iso-PeO)8-AZO were better than of AZO powders. 相似文献
103.
以CuSO_4·5H_2O为原料,KOH为添加剂,酒石酸为还原剂,在水热条件下通过调整相关的实验参数,制备了一系列不同形态的Cu_2O微-纳米晶体及三维十字形枝晶。采用XRD、SEM等手段对不同形态的Cu_2O晶体进行了表征,探讨了不同因素变化对Cu_2O晶体形态的影响。分析认为,晶体生长过程控制了晶体的具体形貌和大小,Cu_2O晶体显露的单形晶面随晶体生长条件的变化而不同。在低温、弱碱性、高浓度溶液中有利于形成八面体形态的Cu_2O晶体,而菱形十二面体单形晶面在高温、强碱性、低浓度溶液中形成的晶体中显露的面积有所增大。 相似文献
104.
Ke Wang Baodan Liu Jing Li Xiaoyuan Liu Yang Zhou Xinglai Zhang Xiaoguo Bi Xin Jiang 《材料科学技术学报》2019,35(4):615-622
TiO_2 nanostructures with strong interfacial adhesion and diverse morphologies have been in-situ grown on Ti foil substrate through a multiple-step method based on conventional plasma electrolytic oxidation(PEO) technology, hydrothermal reaction and ion exchange process. The PEO process is critical to the formation of TiO_2 seeding layer for the nucleation of Na_2Ti_3O_7 and H_2Ti_3O_7 mediates that are strongly attached to the Ti foil. An ion exchange reaction can finally lead to the formation of H_2Ti_3O_7 nanostructures with diverse morphologies and the calcination process can turn the H_2Ti_3O_7 nanostructures into TiO_2 nanostructures with enhanced crystallinity. The morphology of the TiO_2 nanostructures including nanoparticles(NP), nanowhiskers(NWK), nanowires(NW) and nanosheets(NS) can be easily tailored by controlling the NaOH concentration and reaction time during hydrothermal process. The morphology, composition and optical properties of TiO_2 photocatalysts were analyzed using scanning electron microscope(SEM), X-ray diffraction(XRD), photoluminescence(PL) spectroscopy and UV–vis absorption spectrum. Photocatalytic tests indicate that the TiO_2 nanosheets calcined at 500?C show good crystallization and the best capability of decomposing organic pollutants. The decoration of Ag cocatalyst can further improve the photocatalytic performance of the TiO_2 nanosheets as a result of the enhanced charger separation efficiency. Cyclic photocatalytic test using TiO_2 nanostructures grown on Ti foil substrate demonstrates the superior stability in the photodegradation of organic pollutant, suggesting the promising potential of in-situ growth technology for industrial application. 相似文献
105.
Jiang Lei Ding Yang Xue Xialin Zhou Sensen Li Cheng Zhang Xiaoke Jiang Xiqun 《Nano Research》2018,11(11):6062-6073
Nano Research - Developing multifunctional nanoparticles to support new therapy models is a promising and challenging task to address the current dilemma on antitumor treatment. Herein, we... 相似文献
106.
X Jiang M Zhang Y Ding J Yao H Chen D Zhu M Muramatu 《Canadian Metallurgical Quarterly》1998,124(5):980-985
BACKGROUND AND PURPOSE: Mood disorders are common after stroke and may impede physical, functional, and cognitive recovery, making early identification and treatment of potential importance. We aimed to compare the accuracy of the General Health Questionnaire (GHQ-30) and the Hospital Anxiety and Depression (HAD) Scale in detecting psychiatric morbidity after stroke and to determine the most suitable cutoff points for different purposes. METHODS: One hundred five hospital-referred stroke patients completed both the GHQ-30 and HAD Scale 6 months after onset before a blinded psychiatric assessment in which the Schedule for Affective Disorders and Schizophrenia with some supplementary questions was used to determine a DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) diagnosis. Measures were compared in terms of sensitivity, specificity, and receiver operating characteristic curves. RESULTS: No significant differences were found between the GHQ-30 and the HAD Scale in identifying those patients with any DSM-IV diagnosis (P=0.95), grouped depression (P=0.56), or anxiety (P=0.25) disorders. The previously recommended cutoff points for identifying "cases" for the GHQ (4/5) and for the HAD Scale (8/9 and 11/12) were found to be suboptimal in this population. CONCLUSIONS: The GHQ-30 and HAD scale exhibited similar levels of sensitivity and specificity. Data are presented, taking into account the "cost" of false-positives and negatives, to allow a choice of cutoff points suitable for differing situations. 相似文献
107.
Wei-Wei Che Guang-Hong Yang 《International Journal of Control, Automation and Systems》2011,9(5):993-997
The non-fragile dynamic output feedback H
∞ controller design problem is investigated. The controller to be designed is assumed to be with additive gain variations.
A two-step procedure is proposed to develop sufficient conditions for the non-fragile H
∞ controller design by employing the structured vertex separator. A comparison between the proposed and the existing controller
design methods is provided, and a numerical example is carried out to support the theoretical findings. 相似文献
108.
109.
Research on the group decision-making about emergency event based on network technology 总被引:1,自引:1,他引:0
Kefan Xie Gang Chen Qian Wu Yang Liu Pan Wang 《Information Technology and Management》2011,12(2):137-147
In order to improve decision-making efficiency about emergency event, this paper proposes a novel concept, i.e., Agile-Delphi
Method, which is an integration of agile decision and Delphi Method implicating that the decision-makers instantly deliver,
respond, treat, and utilize information via Delphi process while conducting group decision-making about emergency event. The
paper details the mechanism of group decision-making about emergency event based on network technology and Agile-Delphi Method.
Finally, the paper conducts an empiric analysis taking the “111 event”, i.e., the liquid ammonia spill event happened on November
1, 2006 in a phosphorus chemical company in China, as an example. 相似文献
110.
The twisted cube is an important variant of the most popular hypercube network for parallel processing. In this paper, we consider the problem of embedding multi-dimensional meshes into twisted cubes in a systematic way. We present a recursive method for embedding a family of disjoint multi-dimensional meshes into a twisted cube with dilation 1 and expansion 1. We also prove that a single multi-dimensional mesh can be embedded into a twisted cube with dilation 2 and expansion 1. Our work extends some previously known results. 相似文献