全文获取类型
收费全文 | 6382篇 |
免费 | 491篇 |
国内免费 | 115篇 |
专业分类
电工技术 | 267篇 |
综合类 | 205篇 |
化学工业 | 1136篇 |
金属工艺 | 211篇 |
机械仪表 | 218篇 |
建筑科学 | 371篇 |
矿业工程 | 58篇 |
能源动力 | 339篇 |
轻工业 | 519篇 |
水利工程 | 99篇 |
石油天然气 | 196篇 |
武器工业 | 4篇 |
无线电 | 714篇 |
一般工业技术 | 948篇 |
冶金工业 | 440篇 |
原子能技术 | 25篇 |
自动化技术 | 1238篇 |
出版年
2024年 | 13篇 |
2023年 | 100篇 |
2022年 | 195篇 |
2021年 | 253篇 |
2020年 | 197篇 |
2019年 | 201篇 |
2018年 | 255篇 |
2017年 | 231篇 |
2016年 | 261篇 |
2015年 | 238篇 |
2014年 | 266篇 |
2013年 | 525篇 |
2012年 | 376篇 |
2011年 | 465篇 |
2010年 | 375篇 |
2009年 | 366篇 |
2008年 | 310篇 |
2007年 | 264篇 |
2006年 | 257篇 |
2005年 | 207篇 |
2004年 | 144篇 |
2003年 | 159篇 |
2002年 | 211篇 |
2001年 | 147篇 |
2000年 | 112篇 |
1999年 | 71篇 |
1998年 | 114篇 |
1997年 | 94篇 |
1996年 | 74篇 |
1995年 | 70篇 |
1994年 | 64篇 |
1993年 | 44篇 |
1992年 | 29篇 |
1991年 | 17篇 |
1990年 | 25篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 24篇 |
1986年 | 20篇 |
1985年 | 14篇 |
1984年 | 27篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 15篇 |
1973年 | 9篇 |
排序方式: 共有6988条查询结果,搜索用时 15 毫秒
1.
Harizi Riadh Walha Rim Drira Fadoua Zaied Mourad 《Multimedia Tools and Applications》2022,81(3):3091-3106
Multimedia Tools and Applications - Text recognition in the wild is a challenging task in the field of computer vision and machine learning. Existing optical character recognition engines cannot... 相似文献
2.
3.
4.
Effect of cellulose acetate/cellulose triacetate ratio on reverse osmosis blend membrane performance
Yasmeen Elkony El-Sayed Mansour Amel Elhusseiny Shaker Ebrahim 《Polymer Engineering and Science》2020,60(11):2852-2863
Surface functionalization and modification including the grafting process are effective approaches to improve and enhance the reverse osmosis (RO) membrane performance. This work is aimed to synthesize grafted/crosslinked cellulose acetate (CA)/cellulose triacetate (CTA) blend RO membranes using N-isopropylacrylamide (N-IPAAm) as a monomer and N,N-methylene bisacrylamide (MBAAm) as a crosslinker. The morphology of these membranes was analyzed by scanning electron microscopy and their surface roughness was characterized by atomic force microscopy. The performance of these membranes was evaluated through measuring two major parameters of salt rejection and water flux using RO unit at variable operating pressures. It was noted that the surface average roughness obviously decreased from 148 nm for the pure CA/CTA blend membrane with 2.5% CTA to 110 nm and 87 nm for the grafted N-IPAAm and grafted/crosslinked N-IPAAM/MBAAm/CA/CTA-RO membranes, respectively. Moreover, the contact angle decreased from 51.98° to 47.6° and 43.8° after the grafting and crosslinking process. The salt rejection of the grafted CA/CTA-RO membrane by 0.1% N-IPAAm produced the highest value of 98.12% and the water flux was 3.29 L/m2h at 10 bar. 相似文献
5.
Yingcai Bi Menglu Lan Jiaxin Li Shupeng Lai Ben M. Chen 《Asian journal of control》2019,21(4):1732-1744
Micro Aerial Vehicles (MAVs) have great potentials to be applied for indoor search and rescue missions. In this paper, we propose a modular lightweight design of an autonomous MAV with integrated hardware and software. The MAV is equipped with the 2D laser scanner, camera, mission computer and flight controller, running all the computation onboard in real time. The onboard perception system includes a laser‐based SLAM module and a custom‐designed visual detection module. A dual Kalman filter design provides robust state estimation by multiple sensor fusion. Specifically, the fusion module provides robust altitude measurement in the circumstance of surface changing. In addition, indoor‐outdoor transition is explicitly handled by the fusion module. In order to efficiently navigate through obstacles and adapt to multiple tasks, a task tree‐based mission planning method is seamlessly integrated with path planning and control modules. The MAV is capable of searching and rescuing victims from unknown indoor environments effectively. It was validated by our award‐winning performance at the 2017 International Micro Air Vehicle Competition (IMAV 2017), held in Toulouse, France. The performance video is available on https://youtu.be/8H19ppS_VXM . 相似文献
6.
The Journal of Supercomputing - Data center network virtualization is being considered as a promising technology to provide a performance guarantee for cloud computing applications. One important... 相似文献
7.
Enhancement of the dissolution rate of the poorly water-soluble hypoglycemic agent, gliclazide, by the aid of lyophilization was investigated. Mannitol, sodium lauryl sulfate (SLS) and polyvinyl pyrrolidone (PVP-k-30) were employed in different weight ratios (43%, 56% and 64% w/w, respectively) as water-soluble excipients in the formulation. Lyophilized systems were found to exhibit extremely higher in vitro dissolution rate compared to the unprocessed drug powder. Solid state characterization of the lyophilized systems using X-ray powder diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry techniques revealed that dissolution enhancement was attributable to transformation of gliclazide from the crystalline to an amorphous state in the solid dispersion formed during the lyophilization process. The gastrointestinal absorption and hypoglycemic effect of the lyophilized gliclazide/SLS system were investigated following oral administration to Albino rabbits. Cmax and area under the plasma concentration–time curve of gliclazide (AUC0–12) after administration of the lyophilized formulations were significantly higher than those obtained after administration of the unprocessed gliclazide. 相似文献
8.
LNG冷量优化集成利用技术 总被引:7,自引:1,他引:6
我国将相继在沿海地区建成多个LNG接收站,每年将进口数以千万吨计的LNG,同时携带数着巨额冷量,而这些冷量可用于发电、空气分离、制造干冰、低温冷库等众多领域。基于国外LNG冷量利用现状,指出我国即将展开和实施此项技术还存在着:过程火用损较大,缺乏系统、全面的LNG冷量利用技术的研发指导机制,以及宏观调控力度薄弱等问题,进而提出了发展LNG冷量的集成利用方案,可为此类技术的研发利用提供新思路。以福建即将进口的LNG为例,模拟了空气分离与干冰制备的集成工艺流程,结果表明:福建每年进口的260×104t LNG可以冷却290×104t空气,相当于60000 m3/h的氧气制备规模,还可以生产100×104t的干冰,其过程火用损较小;其剩余的高温位冷量可应用于低温冻结库或冰灯等项目,这对主体装置的实施效果和过程火用损的影响较小。该技术的优点在于可灵活控制冷却空气的液化率,基本不用冷却循环水,流程简单,设备投资少,能耗低等。 相似文献
9.
N Haddad R Ben Khelifa H Matter H Kharmachi MF Aubert A Wandeler J Blancou 《Canadian Metallurgical Quarterly》1994,12(4):307-309
The possibility of immunizing dogs orally against rabies, using SADBern, an attenuated strain, was tested on dogs in the field in Tunisia. This strain induced high neutralizing antibody titres and conferred to all vaccinated dogs total resistance against a challenge with a Maghrebian strain. However, an excretion of virus of vaccinal origin was observed in one dog, hampering the use of SADBern in dogs. Nevertheless, this work demonstrates for the first time that dogs in developing countries, especially those which are inaccessible to parenteral vaccination, could be efficiently immunized against rabies by the oral route. 相似文献
10.
AM Mansour K Kassak M Chaya T Hourani A Sibai MN Alameddine 《Canadian Metallurgical Quarterly》1997,81(10):905-906
Here we report a case that presented with sudden onset of neurological symptoms and was treated with ganciclovir. Polymerase chain reaction analysis for human herpes virus-6 (HHV-6) from his cerebrospinal fluid was later found to be positive. He subsequently recovered with minimal residual neurological symptoms. Encephalitis secondary to this virus may be more common than previously thought in patients undergoing bone marrow transplantation. This condition should be considered in the differential diagnosis of sudden onset neurological symptoms after bone marrow transplantation. 相似文献