全文获取类型
收费全文 | 86419篇 |
免费 | 7472篇 |
国内免费 | 4134篇 |
专业分类
电工技术 | 5392篇 |
技术理论 | 5篇 |
综合类 | 6484篇 |
化学工业 | 14073篇 |
金属工艺 | 4588篇 |
机械仪表 | 5452篇 |
建筑科学 | 6692篇 |
矿业工程 | 2477篇 |
能源动力 | 2289篇 |
轻工业 | 7075篇 |
水利工程 | 1670篇 |
石油天然气 | 5184篇 |
武器工业 | 759篇 |
无线电 | 9451篇 |
一般工业技术 | 9810篇 |
冶金工业 | 3782篇 |
原子能技术 | 914篇 |
自动化技术 | 11928篇 |
出版年
2024年 | 390篇 |
2023年 | 1441篇 |
2022年 | 2584篇 |
2021年 | 3442篇 |
2020年 | 2773篇 |
2019年 | 2193篇 |
2018年 | 2503篇 |
2017年 | 2765篇 |
2016年 | 2448篇 |
2015年 | 3383篇 |
2014年 | 4480篇 |
2013年 | 5076篇 |
2012年 | 5663篇 |
2011年 | 6258篇 |
2010年 | 5633篇 |
2009年 | 5259篇 |
2008年 | 5277篇 |
2007年 | 4989篇 |
2006年 | 4802篇 |
2005年 | 4051篇 |
2004年 | 2928篇 |
2003年 | 2484篇 |
2002年 | 2481篇 |
2001年 | 2106篇 |
2000年 | 1910篇 |
1999年 | 1991篇 |
1998年 | 1645篇 |
1997年 | 1390篇 |
1996年 | 1222篇 |
1995年 | 1032篇 |
1994年 | 823篇 |
1993年 | 612篇 |
1992年 | 516篇 |
1991年 | 349篇 |
1990年 | 281篇 |
1989年 | 224篇 |
1988年 | 155篇 |
1987年 | 107篇 |
1986年 | 83篇 |
1985年 | 56篇 |
1984年 | 39篇 |
1983年 | 34篇 |
1982年 | 34篇 |
1981年 | 24篇 |
1980年 | 23篇 |
1979年 | 9篇 |
1976年 | 7篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Shaofeng Wang Jianwei Xu Yuejin Tong Lin Wang Chaobin He 《Polymer International》2005,54(9):1268-1274
A novel cholesterol‐imprinted polymer (CMIP‐H) was prepared by a hybrid method of covalent imprinting and non‐covalent imprinting. This approach involves the copolymerization of a template‐containing monomer, cholesteryl 2‐hydroxyethyl methacrylate carbonate, and a cross‐linker, followed by hydrolysis to afford a flexible guest‐binding site accompanied with the easy and efficient removal of a ‘sacrificial spacer’. The effect of solvent on the binding capacity of CMIP‐H towards cholesterol was studied, indicating that a good binding capacity towards cholesterol could be achieved in a less‐polar solvent. The binding experiments of CMIP‐H towards a series of structural analogues of cholesterol, including cholesterol acetate, progesterone and stigmasterol, were carried out in hexane. The results showed that CMIP‐H almost did not bind cholesterol acetate at all because the hydrogen‐bonding site is blocked. It exhibited a similar binding towards both cholesterol and stigmasterol, but much higher binding towards progesterone. Copyright © 2005 Society of Chemical Industry 相似文献
53.
J.A. Bakken L. Barone D. Braun M. Caillat C. Dionisi C. Dor H. Elmamouni F. Ferroni G.L. Grazer J.T. He R. Herbiet B. Ille P. Lecomte E. Longo P.F. Loverre Y.S. Lu J.P. Martin U. Micke R.P. Mount P.A. Pirou H.-G. Sander D. Schmitz M. Schneegans D.P. Stickland R.L. Sumner K.L. Tung E. Valente M. Vivargent 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,228(2-3):294-302
A calorimeter of 25 bismuth germanate (BGO) crystals equipped with silicon photodiode readout has been tested at the CERN SPS in the energy range 1–50 GeV. The response for electrons has been shown to be linear in this energy range and the rms resolution obtained (
) is approximately 1%, for E > 4 GeV. The electron/pion separation was found to be better than 1:500 in the energy range 1–20 GeV. Data on lateral and longitudinal shower development were compared with the results of a Monte Carlo simulation using the SLAC-EGS program and found to be in good agreement. 相似文献
54.
本文提出一种多输入多输出(MIMO)天线系统中简单的扩展空时块编码(SSTBC)分集技术,采用沃尔什码来区分各天线发送数据子流。采用这种方法,在系统带宽一定时,不降低发送信息速率,同时接收机简单。不同天线的发送信息经过了所有收一发天线对之间的空间子信道,获得了所有路径的部分空间分集增益,仿真结果表明,这种增益的获得不受限于接收分集阶数,并且随发射天线的增加以一定的线性关系增加。 相似文献
55.
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
56.
绍兴市城区河道整治工程若干问题初探 总被引:1,自引:0,他引:1
通过对绍兴城区环城河、大环河、古运河、古城河等河道整治工程内容和整治成效的分析,总结了绍兴城区河道整治的5大特点,针对河道建设中存在的有关问题,提出了今后城市河道整治的4条具体措施。 相似文献
57.
58.
59.
60.
Out-of-plane microlenses and microoptical fiber holder are two of the most important components for building an integrated
microoptic system with a precise alignment accuracy. In this paper, a simple and convenient method to fabricate these components
from SU-8 by using inclined UV lithography in water is proposed. It consists of two perpendicular exposures in SU-8 at ±45°.
DI water possesses a low absorption coefficient and a moderate and stable value of refractive index in near UV. Using water,
the exposure angle in SU-8 can be increased to 50° from 35° in air necessary to pattern the desired 45° slope of the sidewalls.
The principle of the proposed technique and the detailed fabrication process of the microoptic components will be presented.
The integratability of the fabricated components was demonstrated by the fabrication of the microoptical fiber holder with
a pre-aligned out-of-plane microlens. 相似文献