全文获取类型
收费全文 | 949篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 78篇 |
化学工业 | 217篇 |
金属工艺 | 34篇 |
机械仪表 | 13篇 |
建筑科学 | 6篇 |
能源动力 | 38篇 |
轻工业 | 33篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 124篇 |
一般工业技术 | 122篇 |
冶金工业 | 190篇 |
原子能技术 | 13篇 |
自动化技术 | 91篇 |
出版年
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 37篇 |
2011年 | 42篇 |
2010年 | 32篇 |
2009年 | 34篇 |
2008年 | 28篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 31篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 27篇 |
1998年 | 84篇 |
1997年 | 57篇 |
1996年 | 38篇 |
1995年 | 28篇 |
1994年 | 29篇 |
1993年 | 27篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 16篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 9篇 |
排序方式: 共有962条查询结果,搜索用时 359 毫秒
931.
932.
933.
A single-mode fibre with a large core radius and a strong field confinement is shown to be realised by using a dielectric-tube waveguide with an outer higher-index cladding. 相似文献
934.
The influence of the direction of ultraviolet irradiation upon the yields of the photocatalytic decomposition of pure water has been investigated in Pt/TiO2 aqueous suspension system. The yields of the photocatalytic decomposition irradiated from the top of the reaction cell are about 103 times higher than those irradiated from the bottom. The difference seems due to the reverse reaction of the formed H2 and O2 in the suspension. 相似文献
935.
Nishida Y. Koike J. Ohtake H. Abe M. Yoshikawa S. 《Electron Devices, IEEE Transactions on》1989,36(2):360-366
To achieve a high-performance image sensor for a broadcast TV camera, several studies of the noise characteristics of a CCD image sensor are described. The noise perception limit and the dependence of random noise and fixed pattern noise (FPN) on signal charge in a CCD imager were measured to obtain a correlation between measured noise and subjective noise. A method has been devised to measure FPN and random noise separately. Using this method, it has been confirmed that noise can be reduced to less than the perception limit using new noise-suppression techniques 相似文献
936.
Justin C Sanchez Nicolas Alba Toshikazu Nishida Christopher Batich Paul R Carney 《IEEE transactions on neural systems and rehabilitation engineering》2006,14(2):217-221
Long-term viability of chronic invasive neural probes is a necessary condition for extracting robust control signals directly from neural tissue. Although immune/tissue response is a leading factor in the degradation of single neuron recording, we investigate a second component of signal degradation connected to the structural changes associated with microwire electrodes chronically exposed to extracelluar environments in vivo. Scanning electron microscopy is used to assess the surface modifications to the electrodes after an implantation duration of four weeks in rats. The electrode developed a smooth fracture surface, a reduction of the metal diameter, and pitting in the insulation of the electrode structure. Over the duration of implantation, recording properties of the electrode were marked by a reduction in the peak-to-peak amplitude in neuronal firing. 相似文献
937.
This paper describes simple control structures for the vector-controlled stand-alone induction generator (IG) used to operate under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source pulsewidth-modulation (PWM) converter and the three-phase variable-speed squirrel-cage IG to regulate dc link and generator voltages with the newly designed phase-locked loop circuit. The required reactive power for the variable-speed IG is supplied by means of the PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter with the need for only three sensors, and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable-speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good ac and dc voltage regulations. 相似文献
938.
Takashi Kurohara Keita Tanaka Daisuke Takahashi Satoshi Ueda Yasunobu Yamashita Yuri Takada Hirokazu Takeshima Shengwang Yu Yukihiro Itoh Koji Hase Takayoshi Suzuki 《Chembiochem : a European journal of chemical biology》2021,22(22):3158-3163
Pharmacological inhibition of histone deacetylase 6 (HDAC6) is an effective therapeutic strategy for cancer and immunological diseases. Most of the previously reported HDAC6 inhibitors have a hydroxamate group as a zinc binding group (ZBG), which coordinates to the catalytic zinc ion of HDAC6. The hydroxamate group is liable to metabolically generate mutagenetic hydroxylamine; therefore, non-hydroxamate HDAC6 inhibitors would be advantageous. In this study, to identify novel non-hydroxamate HDAC6-selective inhibitors, screening of a chemical library and the subsequent structural optimization were performed, which led to the identification of HDAC6-selective inhibitors with 3,3,3-trifluorolactic amide (TFLAM) as a novel ZBG. The identified inhibitor showed potent and selective HDAC6-inhibitory activity in cells and induced regulatory T (Treg) cell differentiation. 相似文献
939.
The sulfidation behavior of chromium was investigated over a temperature range of 973–1173 K in H2S-H2 gas mixtures of 104–10–6 Pa sulfur partial pressures using thermogravimetry, X-ray diffractometry, optical and scanning electron microscopy, and electron-probe microanalysis. Sulfidation kinetics are rapid for short periods and obey a linear rate law at low sulfur pressures, whereas at high sulfur pressures sulfidation tends to be parabolic. The surface morphologies can be divided into four types: at high sulfur pressures a petal-like crystal of Cr2S3(rho. and tri.) (type 1), at intermediate sulfur pressures a twinlike structure of Cr3S4 (type 2), at low sulfur pressures a flat surface with numerous hexagonal pits of Cr1–xS (type 3), and a fine twinlike structure of ordered Cr1–xS (type 4). At 973 K, the sulfur pressure ranges are type 1 at
> 10–4, type 2 at
, and type 3 at
. The critical sulfur pressure where type 2 was formed, 10–5 Pa at 973 K, shifts toward higherressures at higher temperatures and becomes 10–3 Pa at 1073 K and 10–1 Pa at 1173K. Type 4 is observed at 1173K and 10–6 Pa sulfur pressure. Thesulfide scale is composed of two distinct layers: an external layer, which is dense with a fine columnar structure, and an inner layer, which is porous with a layered structure of sulfides and voids. The external scale is composed offour layers at high sulfur pressures: at the scale-gas interface Cr2S3(rho.), next Cr2S3(tri.), third Cr3S4, and innermost Cr1–xS. With decreasing sulfur pressures,the number of layers in the external scale was reduced. Pt markers were positioned between the external and inner scales.Emeritus Professor. 相似文献
940.
The complete range of binary Fe-Mn alloys were sulfidized in pure sulfur vapor (1 atm) at 700–1000°C. It was found that the corrosion kinetics could be divided into four groups, depending upon the alloy concentration. The first group, up to 11 w/o Mn, had a constant corrosion rate. The second group, up to about 63 w/o Mn, had an exponentially decreasing rate of corrosion with increasing manganese content. In the third group, about 63–80 w/o Mn alloys, the corrosion rate did not follow the parabolic law. The corrosion rates became constant above 80 w/o Mn. These corrosion kinetics were explained by considering the scale structure and alloy substrate. 相似文献