全文获取类型
收费全文 | 175679篇 |
免费 | 12696篇 |
国内免费 | 6541篇 |
学科分类
工业技术 | 194916篇 |
出版年
2024年 | 756篇 |
2023年 | 2496篇 |
2022年 | 4891篇 |
2021年 | 6614篇 |
2020年 | 4963篇 |
2019年 | 4258篇 |
2018年 | 5413篇 |
2017年 | 5933篇 |
2016年 | 5378篇 |
2015年 | 6033篇 |
2014年 | 7797篇 |
2013年 | 9444篇 |
2012年 | 10198篇 |
2011年 | 10859篇 |
2010年 | 9322篇 |
2009年 | 9074篇 |
2008年 | 8907篇 |
2007年 | 8412篇 |
2006年 | 7839篇 |
2005年 | 6663篇 |
2004年 | 5068篇 |
2003年 | 4944篇 |
2002年 | 4988篇 |
2001年 | 4529篇 |
2000年 | 3917篇 |
1999年 | 3495篇 |
1998年 | 2769篇 |
1997年 | 2320篇 |
1996年 | 2067篇 |
1995年 | 1814篇 |
1994年 | 1544篇 |
1993年 | 1287篇 |
1992年 | 1264篇 |
1991年 | 1111篇 |
1990年 | 1110篇 |
1989年 | 1024篇 |
1988年 | 914篇 |
1987年 | 850篇 |
1986年 | 781篇 |
1985年 | 717篇 |
1984年 | 703篇 |
1981年 | 670篇 |
1979年 | 736篇 |
1978年 | 777篇 |
1977年 | 739篇 |
1976年 | 755篇 |
1975年 | 713篇 |
1974年 | 719篇 |
1973年 | 723篇 |
1972年 | 705篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry 相似文献
102.
103.
N. Ya. Kydryavtseva Yu. N. Gromov V. A. Kotofeev 《Metal Science and Heat Treatment》1991,33(5):349-352
Conclusions Of all of the tested forms of hardening with chemicothermal treatment single-phase boriding and chrome-vanadizing provide the best combination of service properties of 5KhNM steel.Kemerovo Technological Institute for the Food Industry. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 7–8, May, 1991. 相似文献
104.
105.
106.
Yanping Li Jinzhong Yu Shaowu Chen 《Photonics Technology Letters, IEEE》2005,17(8):1641-1643
A rearrangeable nonblocking 4/spl times/4 thermooptic silicon-on-insulator waveguide switch matrix at 1.55-/spl mu/m integrated spot size converters is designed and fabricated for the first time. The insertion losses and polarization-dependent losses of the four channels are less than 10 and 0.8 dB, respectively. The extinction ratios are larger than 20 dB. The response times are 4.6 /spl mu/s for rising edge and 1.9 /spl mu/s for falling edge. 相似文献
107.
N. N. Belov Yu. A. Biryukov A. T. Roslyak N. T. Yugov S. A. Afanas’eva 《Theoretical Foundations of Chemical Engineering》2005,39(3):307-312
A new circulation pneumatic crusher capable of producing submicron powders of refractory materials is presented. A mathematical model is constructed for the dynamic breaking of ceramic macroparticles. This model allows the basic laws of shock-wave crushing in the circulation pneumatic apparatus to be analyzed.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 327–333.Original Russian Text Copyright © 2005 by Belov, Biryukov, Roslyak, Yugov, Afanas’ev. 相似文献
108.
109.
V. Ya. Chubar' Zaporozhe Machine Building Institute. Translated from Problemy Prochnosti, No. 3, pp. 62–65, March, 1989. 相似文献
110.
A numerical solution of the inverse problem of the gravitational field at a single point is obtained using six field elements
for a point, a spherical cap, a differential spherical sector and a vertical segment. In the system of six equations obtained,
the unknowns are the mass of the body, the depth of its center, and the second, third, and fourth degree moments. The accuracy
of the solution of this system is ten times higher than when using three field elements.
__________
Translated from Izmeritel’naya Tekhnika, No. 5, pp. 3–8, May, 2007. 相似文献