全文获取类型
收费全文 | 84234篇 |
免费 | 8988篇 |
国内免费 | 5793篇 |
专业分类
电工技术 | 6632篇 |
技术理论 | 1篇 |
综合类 | 8356篇 |
化学工业 | 12327篇 |
金属工艺 | 5601篇 |
机械仪表 | 5891篇 |
建筑科学 | 6131篇 |
矿业工程 | 3560篇 |
能源动力 | 2355篇 |
轻工业 | 8042篇 |
水利工程 | 2296篇 |
石油天然气 | 3740篇 |
武器工业 | 1202篇 |
无线电 | 8618篇 |
一般工业技术 | 7724篇 |
冶金工业 | 3264篇 |
原子能技术 | 1356篇 |
自动化技术 | 11919篇 |
出版年
2024年 | 377篇 |
2023年 | 1381篇 |
2022年 | 3147篇 |
2021年 | 4153篇 |
2020年 | 3033篇 |
2019年 | 2235篇 |
2018年 | 2440篇 |
2017年 | 2639篇 |
2016年 | 2342篇 |
2015年 | 3721篇 |
2014年 | 4817篇 |
2013年 | 5663篇 |
2012年 | 6792篇 |
2011年 | 6988篇 |
2010年 | 6586篇 |
2009年 | 6281篇 |
2008年 | 6358篇 |
2007年 | 5993篇 |
2006年 | 5160篇 |
2005年 | 4137篇 |
2004年 | 3177篇 |
2003年 | 2345篇 |
2002年 | 2324篇 |
2001年 | 2076篇 |
2000年 | 1520篇 |
1999年 | 936篇 |
1998年 | 478篇 |
1997年 | 361篇 |
1996年 | 336篇 |
1995年 | 303篇 |
1994年 | 223篇 |
1993年 | 167篇 |
1992年 | 90篇 |
1991年 | 79篇 |
1990年 | 69篇 |
1989年 | 70篇 |
1988年 | 44篇 |
1987年 | 38篇 |
1986年 | 26篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1959年 | 12篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
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.
针对伊拉克米桑油田盐膏层巨厚、钻井液密度窗口窄、存在高压盐水层,储层段漏塌同层导致复杂时效高等问题,通过对比分析国内外盐膏层和窄压力窗口地层钻井技术,总结了米桑油田钻井面临的主要技术难点,从井身结构优化、钻井提速和复杂预防等方面入手,研究形成了适合米桑油田的钻井关键技术,并进行了现场试验应用,取得了显著的效果.伊拉克米桑油田钻井关键技术对该地区钻井技术方案设计和钻井提速提效具有较强的借鉴和指导作用. 相似文献
6.
7.
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
8.
采用水溶液聚合法制备了低分子量聚丙烯酸钾(PAAK),并作为新型消焰剂加入单基发射药中。通过火焰原子吸收光谱法测试了PAAK中钾的含量;用乌氏黏度计测定了特性黏度;采用DSC法研究不同pH值的PAAK与硝化棉(NC)的相容性;利用充氮氧弹法对添加PAAK、硝酸钾KNO3、硫酸钾K2SO4的单基发射药的燃烧残渣进行了对比研究。结果表明,合成的PAAK中,钾的质量分数为15.21%,相对分子量在3 000左右,有利于和NC均匀混合,且在中性或微碱性(pH=7.0~7.5)的情况与NC相容性良好。与传统的KNO3、K2SO4消焰剂相比,PAAK能够和NC均匀混合,制备均质透明的单基发射药;PAAK发射药的燃烧残渣最少,占发射药质量的0.18%。 相似文献
9.
为了提高煤炭资源回收率,对岳城煤矿3号煤三盘区最后两个小工作面回采区域的回收布置进行了研究,利用巷道外错布置工艺,对该区域进行整体布置,优化工作面设计,既回采了两个小工作面,又回收了与1308工作面之间的煤柱和原南河滩煤矿的部分大巷煤柱,增加了资源回收,简化了生产系统,实现了科学高效回采。 相似文献
10.
The fracture behaviour and morphologies of high-strength boron steel were investigated at different temperatures at a constant strain rate of 0.1 s-1 based on isothermal tensile tests. Fracture mechanisms were also analyzed based on the relationship between microstructure transformation and continuous cooling transformation(CCT) curves. It is found that 1) fractures of the investigated steel at high temperatures are dimple fractures; 2) the deformation of high-strength boron steel at high temperatures accelerates diffusion transformations; thus, to obtain full martensite, a higher cooling rate is needed; and 3) the investigated steel has the best plasticity when the deformation temperature is 750 °C. 相似文献