全文获取类型
收费全文 | 63358篇 |
免费 | 6575篇 |
国内免费 | 3580篇 |
专业分类
电工技术 | 4621篇 |
技术理论 | 2篇 |
综合类 | 4910篇 |
化学工业 | 9943篇 |
金属工艺 | 3775篇 |
机械仪表 | 4552篇 |
建筑科学 | 4961篇 |
矿业工程 | 2202篇 |
能源动力 | 1708篇 |
轻工业 | 5052篇 |
水利工程 | 1404篇 |
石油天然气 | 2943篇 |
武器工业 | 637篇 |
无线电 | 7563篇 |
一般工业技术 | 6686篇 |
冶金工业 | 2359篇 |
原子能技术 | 793篇 |
自动化技术 | 9402篇 |
出版年
2024年 | 263篇 |
2023年 | 1040篇 |
2022年 | 2268篇 |
2021年 | 3100篇 |
2020年 | 2427篇 |
2019年 | 1893篇 |
2018年 | 2101篇 |
2017年 | 2299篇 |
2016年 | 2157篇 |
2015年 | 3297篇 |
2014年 | 4014篇 |
2013年 | 4470篇 |
2012年 | 5007篇 |
2011年 | 5329篇 |
2010年 | 4620篇 |
2009年 | 4248篇 |
2008年 | 4055篇 |
2007年 | 3672篇 |
2006年 | 3353篇 |
2005年 | 2593篇 |
2004年 | 1935篇 |
2003年 | 1534篇 |
2002年 | 1631篇 |
2001年 | 1351篇 |
2000年 | 1020篇 |
1999年 | 908篇 |
1998年 | 601篇 |
1997年 | 460篇 |
1996年 | 447篇 |
1995年 | 368篇 |
1994年 | 265篇 |
1993年 | 207篇 |
1992年 | 135篇 |
1991年 | 97篇 |
1990年 | 81篇 |
1989年 | 88篇 |
1988年 | 51篇 |
1987年 | 29篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1959年 | 6篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
Chenchen Zhou Jia Man Haibo Yu He Xia Luming Man Bin Qi Jianfeng Li 《Ceramics International》2021,47(8):10866-10872
Ceramic microparticles have great potentials in various fields such as materials engineering, biotechnology, microelectromechanical systems, etc. Morphology of the microparticle performs an important role on their application. To date, it remains difficult to find an effective and controllable way for fabricating nonspherical ceramic microparticles with 3D features. This work demonstrates a method that combines UV light lithography and single emulsion opaque-droplet-templated microfluidic molding to prepare the crescent-shaped ceramic microparticles. By tailoring the intensity of UV light and flow rate of fluid, the shapes of microparticles are accordingly tuned. Therefore, varieties of crescent-shaped microparticles and their variations have been fabricated. After sintering, the crescent-shaped alumina ceramic microparticles were obtained. Benefitting from the light absorption and scattering behavior of most ceramic nanoparticles, this system can serve as a general platform to produce crescent-shaped microparticles made from different materials, and hold great potentials for applications in microrobotics, structural materials in MEMS, and biotechnology. 相似文献
3.
针对煤矸石粉替代率50%、聚酯纤维掺量0.4%的沥青混合料,开展盐冻耦合作用(NaCl溶液质量分数为0%、7.0%、13.0%、26.5%,冻融循环次数为0、2、4、6、8)下的半圆弯曲(SCB)试验,分析了盐冻耦合作用对SCB试件内部损伤劣化过程的影响.结果表明:NaCl溶液质量分数为13.0%、冻融循环为8次时,盐冻耦合作用对沥青混合料的侵蚀破坏作用最强,试件内部损伤最严重;在煤矸石粉与矿粉质量比为1∶1、聚酯纤维掺量为0.4%的条件下,沥青混合料能够形成高黏性、致密、厚实的沥青膜以及由纤维形成的三维网状结构,从而显著降低盐冻侵蚀对沥青混合料的损伤.通过Poly2D模型对SCB试件的极限拉应力损伤量进行拟合,拟合系数为0.944. 相似文献
4.
Jia Dai Xiang Cheng Xiaofeng Li Zhisheng Wang Yufeng Wang Jing Zheng Jun Liu Jiawei Chen Changjin Wu Jinyao Tang 《Advanced functional materials》2021,31(48):2106204
Synthetic active matters are perfect model systems for non-equilibrium thermodynamics and of great potential for novel biomedical and environmental applications. However, most applications are limited by the complicated and low-yield preparation, while a scalable synthesis for highly functional microswimmers is highly desired. In this paper, an all-solution synthesis method is developed where the gold-loaded titania-silica nanotree can be produced as a multi-functional self-propulsion microswimmer. By applying light, heat, and electric field, the Janus nanotree demonstrated multi-mode self-propulsion, including photochemical self-electrophoresis by UV and visible light radiation, thermophoresis by near-infrared light radiation, and induced-charge electrophoresis under AC electric field. Due to the scalable synthesis, the Janus nanotree is further demonstrated as a high-efficiency, low-cost, active adsorbent for water decontamination, where the toxic mercury ions can be reclaimed with enhanced efficiency. 相似文献
5.
6.
Scientometrics - Examining the relationships among scientific disciplines is important today, but existing methods are limited by the contents and structure of their bibliographic databases. We... 相似文献
7.
Neural Processing Letters - This paper presents an approach to identify the unknown parameters of genetic regulatory network (GRN) in finite-time. The adaptive synchronization-based method is used... 相似文献
8.
The slight-alkalization of generator internal cooling water (GICW) is widely used to inhibit the corrosion of hollow copper conductor and thereby ensure the safe operation of the generator. CO2 inleakage is increasingly identified as a potential security risk for GICW system. In this paper, the influence of CO2 inleakage on the slight-alkalization of GICW was theoretically discussed. Based on the equilibriums of the CO2-NaOH-H2O system, CO2 inleakage saturation was derived to quantify the amount of the dissolved CO2 in GICW. This parameter can be directly calculated with the measured conductivity and the [Na+] of GICW. The influence of CO2 inleakage on the slight-alkalization conditioning of GICW and the measurement of its water quality parameters were then analyzed. The more severe the inleakage, the narrower the water quality operation ranges of GICW, resulting in the more difficult the slight-alkalization conditioning of GICW. The temperature calibrations of the conductivity and the pH value of GICW show non-linear correlations with the amount of CO2 inleakage and the NaOH dosage. This study provides insights into the influence of CO2 inleakage on the slight-alkalization of GICW, which can serve as the theoretical basis for the actual slight-alkalization when CO2 inleakage occurs. 相似文献
9.