全文获取类型
收费全文 | 25289篇 |
免费 | 2289篇 |
国内免费 | 989篇 |
专业分类
电工技术 | 732篇 |
技术理论 | 2篇 |
综合类 | 4186篇 |
化学工业 | 2863篇 |
金属工艺 | 707篇 |
机械仪表 | 1546篇 |
建筑科学 | 5943篇 |
矿业工程 | 972篇 |
能源动力 | 520篇 |
轻工业 | 1082篇 |
水利工程 | 848篇 |
石油天然气 | 1721篇 |
武器工业 | 160篇 |
无线电 | 1261篇 |
一般工业技术 | 2541篇 |
冶金工业 | 1041篇 |
原子能技术 | 91篇 |
自动化技术 | 2351篇 |
出版年
2024年 | 67篇 |
2023年 | 372篇 |
2022年 | 638篇 |
2021年 | 763篇 |
2020年 | 835篇 |
2019年 | 647篇 |
2018年 | 567篇 |
2017年 | 633篇 |
2016年 | 705篇 |
2015年 | 884篇 |
2014年 | 1764篇 |
2013年 | 1503篇 |
2012年 | 1978篇 |
2011年 | 1998篇 |
2010年 | 1774篇 |
2009年 | 1651篇 |
2008年 | 1309篇 |
2007年 | 1624篇 |
2006年 | 1355篇 |
2005年 | 1169篇 |
2004年 | 1093篇 |
2003年 | 910篇 |
2002年 | 738篇 |
2001年 | 741篇 |
2000年 | 625篇 |
1999年 | 441篇 |
1998年 | 307篇 |
1997年 | 293篇 |
1996年 | 246篇 |
1995年 | 209篇 |
1994年 | 131篇 |
1993年 | 119篇 |
1992年 | 92篇 |
1991年 | 63篇 |
1990年 | 63篇 |
1989年 | 63篇 |
1988年 | 30篇 |
1987年 | 34篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 18篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1964年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
以“创新、协调、绿色、开放、共享”为内核的新发展理念,是对马克思主义发展理念的继承和发扬,极具时代精神,富含问题意识,为高校思想政治教育发展、教育教学改革实践提供了强大的理论支撑。本文以“通信原理”为例,阐述了新发展理念在课程改革中的思路和方法,实现了思想政治教育与专业基础课程有机融合,为深化高校教学改革、创新人才培养模式提供了思路。 相似文献
3.
4.
Donghai Xu Peng Feng Yang Wang Wanpeng Yang Yu Wang Shaoyan Sun 《American Institute of Chemical Engineers》2022,68(2):e17472
Corrosion and salt deposition problems severely restrict the industrialization of supercritical water oxidation. Transpiring wall reactor can effectively weaken these two problems by a protective water film. In this work, methanol was selected as organic matter, and the influences of vital structural parameters on water film properties and organic matter removal were studied via numerical simulation. The results indicate that higher than 99% of methanol conversion could be obtained and hardly affected by transpiration water layer, transpiring wall porosity and inner diameter. Increasing layer and porosity reduced reactor center temperature, but inner diameter's influence was lower relatively. Water film temperature reduced but coverage rate raised as layer, porosity, and inner diameter increased. Notably, the whole reactor was in supercritical state and coverage rate was only approximately 85% in the case of one layer. Increasing reactor length affected slightly the volume of the upper supercritical zone but enlarged the subcritical zone. 相似文献
5.
6.
Ewa Bczyska Katarzyna Karolina Pels Subhadip Basu Jakub Wodarczyk Baej Ruszczycki 《International journal of molecular sciences》2021,22(8)
Numerous brain diseases are associated with abnormalities in morphology and density of dendritic spines, small membranous protrusions whose structural geometry correlates with the strength of synaptic connections. Thus, the quantitative analysis of dendritic spines remodeling in microscopic images is one of the key elements towards understanding mechanisms of structural neuronal plasticity and bases of brain pathology. In the following article, we review experimental approaches designed to assess quantitative features of dendritic spines under physiological stimuli and in pathological conditions. We compare various methodological pipelines of biological models, sample preparation, data analysis, image acquisition, sample size, and statistical analysis. The methodology and results of relevant experiments are systematically summarized in a tabular form. In particular, we focus on quantitative data regarding the number of animals, cells, dendritic spines, types of studied parameters, size of observed changes, and their statistical significance. 相似文献
7.
《中国有色金属学会会刊》2021,31(8):2468-2478
An acoustic emission (AE) experiment was carried out to explore the AE location accuracy influenced by temperature. A hollow hemispherical specimen was used to simulate common underground structures. In the process of heating with the flame, the pulse signal of constant frequency was stimulated as an AE source. Then AE signals received by each sensor were collected and used for comparing localization accuracy at different temperatures. Results show that location errors of AE keep the same phenomenon in the early and middle heating stages. In the later stage of heating, location errors of AE increase sharply due to the appearance of cracks. This provides some beneficial suggestions on decreasing location errors of structural cracks caused by temperature and improves the ability of underground structure disaster prevention and control. 相似文献
8.
《中国有色金属学会会刊》2021,31(9):2740-2749
CrAlYN coatings with different Y contents (0, 5 and 12 at.%) were deposited by cathodic arc evaporation to investigate the influence of Y-addition on the structure, mechanical and thermal properties of CrAlN coatings by using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermal gravimetric analysis and nanoindentation. The structural transformation of single phase cubic Cr0.42Al0.58N and Cr0.39Al0.56Y0.05N coatings to cubic–wurtzite mixed Cr0.32Al0.56Y0.12N coating leads to a drop in hardness from (30.2±0.7) GPa of Cr0.42Al0.58N and (32.0±1.0) GPa of Cr0.39Al0.56Y0.05N to (25.2±0.7) GPa of Cr0.32Al0.56Y0.12N. The incorporation of 5 at.% Y retards the thermal decomposition of CrAlN, verified by the postponed precipitation of w-AlN and N-loss upon annealing. Correspondingly, Cr0.39Al0.56Y0.05N coating consistently exhibits the highest hardness value during thermal annealing. Nevertheless, alloying with Y exerts an adverse effect on the oxidation resistance of CrAlN. 相似文献
9.
Patterned photonic crystals with structural colors on textile substrates have attracted a special attention due to the great advantages in application, which currently become a research hot-spot. This study utilized an ink-jet printing technology to prepare high-quality photonic crystal patterns with structural colors on polyester substrates. The self-assembly temperature of poly(styrene-N-methylol acrylamide) (P(St-NMA)) microspheres set to construct photonic crystals were deeply optimized. Moreover, the structural colors of prepared photonic crystal patterns were characterized and evaluated. When the mass fraction of P(St-NMA) microspheres was 1.0 wt.%, the pH value ranged from 5 to 7, and the surface tension was in the range of 63.79 to 71.20 mN/m, inks could present the best print performance. At 60 °C, prepared P(St-NMA) microsphere inks were good for printing to obtain patterned photonic crystals with regular arrangement and beautiful structural colors. Specifically, photonic crystals with different colors could be constructed by regulating the diameter of microspheres in inks, and prepared structural colors exhibited distinct iridescent phenomenon. The present results could provide a theoretical basis for the industrial realization of patterned photonic crystals by ink-jet printing technology. 相似文献
10.
为探究用电脑横编机开发全成形针织产品的可能性,以针织三维全成形口罩为开发对象,进行结构建模与工艺实践。首先对人体面部尺寸进行测量,以此确定全成形口罩的二维纸样;然后结合全成形口罩规格尺寸进行工艺计算,以四针床电脑横编机和SDS-ONE APEX3系统为开发工具,分别建立针织三维全成形口罩的口罩主体、过滤垫片口袋开口、挂耳带部位的结构模型。结果表明:通过对口罩的规格设计并建立结构模型,同时结合工艺参数的调节并优化其生产技术,可实现兼具美观性与舒适性三维全成形口罩的快速生产,结合功能性原料可开发高附加值的口罩产品。 相似文献