全文获取类型
收费全文 | 6629篇 |
免费 | 918篇 |
国内免费 | 474篇 |
专业分类
电工技术 | 424篇 |
综合类 | 695篇 |
化学工业 | 890篇 |
金属工艺 | 298篇 |
机械仪表 | 371篇 |
建筑科学 | 660篇 |
矿业工程 | 236篇 |
能源动力 | 118篇 |
轻工业 | 345篇 |
水利工程 | 206篇 |
石油天然气 | 220篇 |
武器工业 | 95篇 |
无线电 | 1134篇 |
一般工业技术 | 474篇 |
冶金工业 | 335篇 |
原子能技术 | 463篇 |
自动化技术 | 1057篇 |
出版年
2024年 | 23篇 |
2023年 | 80篇 |
2022年 | 169篇 |
2021年 | 167篇 |
2020年 | 173篇 |
2019年 | 188篇 |
2018年 | 185篇 |
2017年 | 225篇 |
2016年 | 292篇 |
2015年 | 331篇 |
2014年 | 447篇 |
2013年 | 598篇 |
2012年 | 467篇 |
2011年 | 484篇 |
2010年 | 396篇 |
2009年 | 435篇 |
2008年 | 361篇 |
2007年 | 395篇 |
2006年 | 358篇 |
2005年 | 319篇 |
2004年 | 272篇 |
2003年 | 270篇 |
2002年 | 234篇 |
2001年 | 231篇 |
2000年 | 185篇 |
1999年 | 169篇 |
1998年 | 111篇 |
1997年 | 99篇 |
1996年 | 71篇 |
1995年 | 65篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 26篇 |
1991年 | 22篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1971年 | 3篇 |
1964年 | 3篇 |
1961年 | 3篇 |
1959年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有8021条查询结果,搜索用时 15 毫秒
1.
In this paper, we present LinkingPark, an automatic semantic annotation system for tabular data to knowledge graph matching. LinkingPark is designed as a modular framework which can handle Cell-Entity Annotation (CEA), Column-Type Annotation (CTA), and Columns-Property Annotation (CPA) altogether. It is built upon our previous SemTab 2020 system, which won the 2nd prize among 28 different teams after four rounds of evaluations. Moreover, the system is unsupervised, stand-alone, and flexible for multilingual support. Its backend offers an efficient RESTful API for programmatic access, as well as an Excel Add-in for ease of use. Users can interact with LinkingPark in near real-time, further demonstrating its efficiency. 相似文献
2.
Atsuki Yamaguchi Kazuki Fukui Yuki Fujiwara Shingo Tamaki Sachie Kusaka Fuminobu Sato 《Journal of Nuclear Science and Technology》2021,58(1):80-86
ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV. 相似文献
3.
对鞍钢股份无缝钢管厂连轧机前毛管坯横移装置存在的设计缺陷进行了分析,并提出改进方案,将原横移装置由高架轨道横移机构及上下升降链传动装置,改进为地面轨道横移系统及同步旋转臂实现取管、放管过程。实施后消除了生产故障,缩短了轧制周期,降低生产成本。 相似文献
4.
As haze intensifies in China, controlling haze emission has become the country's top priority for environmental protection. Because haze moves across different regions, it is necessary to develop a data envelopment analysis (DEA) model underpinned by both competition and cooperation to evaluate the haze emission efficiency in different provinces. This study innovatively adopts the spatial econometrics to construct the co-opetition matrices of Chinese provinces, then builds the co-opetition DEA model to evaluate the haze emission efficiency of them, and finally uses the haze data of 2015 as an example to assess the applicability of the model. The results of the study include the following: First, compared with the traditional CCR (A. Charnes & W. W. Cooper & E. Rhodes) model, this study constructs the co-opetition DEA cross-efficiency model that integrates haze's feature of cross-border moving; thus, it is more in line with the reality of haze emission and movement. Second, compared with the efficiency value gained from the CCR model, the haze emission efficiency values for Tianjin and Guangdong, two decision-making units, register greater variance when using the DEA model. The reason might lie in that they have a different spatial transportation relationship with their surrounding provinces. Third, the haze emission efficiency of provinces, according to the evaluation based on the co-opetition DEA method, varies greatly: Those with high efficiency are mostly inland provinces with slow economic growth and adverse climatic conditions, whereas many of the provinces with low efficiency are located in the relatively prosperous East China. The specific co-opetition DEA model constructed in this study enriches the research on the DEA model, which can be applied to the emission efficiency evaluation of similar pollutants around the world and can contribute empirical support to the haze reducing efforts of the government with its empirical results. 相似文献
5.
实时数据管理系统是流程企业控制信息网络与管理信息网络平滑集成的基础,为两者的数据通讯提供桥梁。介绍了笔者在炼油化工C企业IMS建设中的实时数据管理引擎设计与开发,具有其先进性与实用性。 相似文献
6.
7.
Polymer networks in which poly(propylene imine) dendrimers (Astramol?) are connected to each other by linear polytetrahydrofuran (polyTHF) segments, were prepared by two methods. The first method was a one‐step procedure in which bifunctionally living polyTHF, obtained by initiation of the THF polymerization with trifluoromethane sulfonic anhydride (triflic anhydride), was reacted with an amino‐dendrimer. This reaction was very fast but did not allow formation of the end products. The second method was a two‐step procedure. In a first step, living polyTHF, prepared with acryloyloxybutyl triflate as initiator, was grafted on an amino‐dendrimer, to form a star‐like, acrylate‐terminated polyTHF multi‐macromonomer with the dendrimer as core. In a second step, networks were obtained by Michael addition between the acrylate end‐groups and unreacted amino‐groups of the dendrimer. This cross‐linking reaction occurred spontaneously upon heating of the solution of the multi‐macromonomer with gelation times varying from a few minutes to a few hours, depending on the temperature and the composition of the prepolymers. With this method it was possible to prepare networks in the form of coatings or films. © 2003 Society of Chemical Industry 相似文献
8.
9.
目标RCS动态数据的分布特征研究 总被引:1,自引:0,他引:1
复杂目标在不同视向的RCS分布特征是不同的,传统模型对此都没有给出详细的结果。文中以某歼击机和直升机为对象,应用X^2。分布、对数正态分布和瑞利分布模型,以及Kolmogomv拟合优度检验方法,研究其RCS动态测量数据的统计分布特征,得到了在一定显著性水平下,两种目标在不同视向角下对三种模型的拟合效果,同时得到应用X^2。分布拟合时模型半自由度随视向角的分布情况。在显著性水平为0.05时,对于在较短时间内录得的复杂目标动态RCS数据,应用X^2分布可以取得较好的拟合效果。文中结果精确地描述了目标RCS的起伏特征,能够为目标回波的精确模拟与检测提供可靠的依据。 相似文献
10.