全文获取类型
收费全文 | 8353篇 |
免费 | 1503篇 |
国内免费 | 488篇 |
专业分类
电工技术 | 888篇 |
综合类 | 786篇 |
化学工业 | 2496篇 |
金属工艺 | 336篇 |
机械仪表 | 363篇 |
建筑科学 | 272篇 |
矿业工程 | 124篇 |
能源动力 | 283篇 |
轻工业 | 426篇 |
水利工程 | 74篇 |
石油天然气 | 599篇 |
武器工业 | 78篇 |
无线电 | 1162篇 |
一般工业技术 | 871篇 |
冶金工业 | 376篇 |
原子能技术 | 43篇 |
自动化技术 | 1167篇 |
出版年
2024年 | 35篇 |
2023年 | 195篇 |
2022年 | 278篇 |
2021年 | 303篇 |
2020年 | 368篇 |
2019年 | 397篇 |
2018年 | 296篇 |
2017年 | 346篇 |
2016年 | 450篇 |
2015年 | 402篇 |
2014年 | 579篇 |
2013年 | 588篇 |
2012年 | 598篇 |
2011年 | 527篇 |
2010年 | 442篇 |
2009年 | 494篇 |
2008年 | 467篇 |
2007年 | 528篇 |
2006年 | 492篇 |
2005年 | 383篇 |
2004年 | 367篇 |
2003年 | 320篇 |
2002年 | 265篇 |
2001年 | 227篇 |
2000年 | 202篇 |
1999年 | 151篇 |
1998年 | 110篇 |
1997年 | 82篇 |
1996年 | 69篇 |
1995年 | 76篇 |
1994年 | 72篇 |
1993年 | 47篇 |
1992年 | 46篇 |
1991年 | 21篇 |
1990年 | 23篇 |
1989年 | 25篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1956年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
Synthesis of novel nonionic surfactants has attracted attention of synthetic chemists due to the issues of the currently used commercial surfactants. The synthesis of three biocompatible triazole-based nonionic surfactants is reported for nanovesicular drug loading. The surfactants were synthesized in a three-step reaction and characterized using 1HNMR and mass spectroscopy techniques. They were investigated for their critical micelle concentration (CMC) using a UV–Visible spectrophotometer. Their biocompatibility was investigated against cell culture and in blood. All the synthesized nonionic surfactants were further explored for their nanovesicular drug loading using clarithromycin as a model hydrophobic drug. Nonionic surfactants revealed lower CMC in 35–45 μM and were less hemolytic and cytotoxic. They were capable of self-assembling in nanosize niosomal vesicles encapsulating increased amounts of drug. The results suggest the synthesized nonionic surfactants as biocompatible nanotechnology-based drug-delivery vehicles. 相似文献
3.
4.
This letter presents a new polarizer which has a simple comb structure inside a circular waveguide. The electrical performance of the proposed comb polarizer is optimized by a circular waveguide radius and by the physical parameters of the comb plates. This polarizer is suitable for providing good performance in millimeter‐band application because of its simple structure and low fabrication cost. In our experiments the dual‐band comb polarizer designed in band 1(K) and band 2(Ka) showed good electrical performance without any tuning elements. 相似文献
5.
IEEE 802.11g性能分析及应用 总被引:1,自引:1,他引:0
全面介绍IEEE802.11g标准的无线局域网,详细讲述IEEE802.11g草案标准的概念、产生背景、特点、构件及其体系结构和发展前景,探讨实现IEEE802.11gWLAN所需的关键技术及其双频多模应用方式,同时分析IEEE802.11g标准的网络性能。 相似文献
6.
7.
The feature scale planarization of the copper chemical mechanical planarization (CMP) process has been characterized for two
copper processes using Hitachi 430-TU/Hitachi T605 and Cabot 5001/Arch Cu10K consumables. The first process is an example
of an abrasive-free polish with a high-selectivity barrier slurry, while the second is an example of a conventional abrasive
slurry with a low-selectivity barrier slurry. Copper fill planarization has been characterized for structures with conformal
deposition as well as with bumps resulting from bottom-up fill. Dishing and erosion were characterized for several structures
after clearing. The abrasive-free polish resulted in low sensitivity to overpolish and low saturation levels for dishing and
erosion. Consequently, this demonstrated superior performance when compared to the International Technology Roadmap for Semiconductors
(ITRS) 2000 roadmap targets for planarization. While the conventional slurry could achieve the 0.13-μm technology node requirements,
the abrasive-free polish met the planarization requirements beyond the 0.10-μm technology node. 相似文献
8.
本文报导一种新型的光纤氧、二氧化碳复合传感器.通过在同一敏感膜载体上固定两种不同的荧光试剂——芘丁酸及羟基芘三磺酸,制作了一种对氧和二氧化碳敏感的复合敏感膜.该传感器在医学临床检验范围内具有良好的线性,其测氧的分辩率是0.1%,测二氧化碳的分辩率是0.5%,响应时间短于1min.文中还讨论了三种敏感膜载体的比较及复合传感器测量进程中氧和二氧化碳的相互干扰问题. 相似文献
9.
BaMgAl10O17∶Eu2 (BAM) was prepared in the microemulsion system and its phase behavior was studied. There exists a small region in the reverse microemulsion system where the dispersed particles are of spherical form. In this way, BAM blue phosphor with good dispersion can be synthesized. The microemulsion phase diagrams of the pseudo-ternary system (Triton X-100/cosurfactant-oil-BAM brine) were first established intuitively by the dilution method. The microstructure of microemulsions was determined through eyeballing, conductance technique, and polar optical microscopy. Its phase behavior is affected by various factors, such as temperature (room temperature, 30, 40 ℃), oil, surfactants, and cosurfactants in microemulsions. According to the phase diagrams, the microemulsion system of Triton X-100/1-hexanol-hexane-BAM brine was chosen to prepare the precursor. The BAM phosphor can be obtained via sintering the precursor at a comparatively low temperature. The phosphors were characterized by XRD and vacuum ultraviolet (VUV) spectra. 相似文献
10.
《Particulate Science and Technology》2007,25(1):77-89
The removal of particulate contamination is a critical issue for many manufacturing processes. It is particularly critical to the electronics industry in which small pieces of microscopic debris remaining after chemical mechanical planarization (cmp) using submicron polishing particles can cause device failure. One way to enhance particle removal following the cmp process is to utilize surfactants. Recent research has shown ways to model the effect of surfactants on enhanced particle removal. However, previous research has not demonstrated the effect of ionic strength on enhanced particle removal associated with surfactant use. Past research has also not shown the combined effects of ionic strength and surfactant concentration on enhanced particle removal using surfactants. This article summarizes the parameters affecting particle removal, and it provides data and analysis on the effect of ionic strength as well as the combined effects of ionic strength and surfactant concentration on particle removal following cmp processing. 相似文献