全文获取类型
收费全文 | 22564篇 |
免费 | 1625篇 |
国内免费 | 80篇 |
专业分类
电工技术 | 316篇 |
综合类 | 28篇 |
化学工业 | 4930篇 |
金属工艺 | 706篇 |
机械仪表 | 1364篇 |
建筑科学 | 486篇 |
矿业工程 | 8篇 |
能源动力 | 886篇 |
轻工业 | 1915篇 |
水利工程 | 117篇 |
石油天然气 | 17篇 |
无线电 | 4172篇 |
一般工业技术 | 4816篇 |
冶金工业 | 1591篇 |
原子能技术 | 307篇 |
自动化技术 | 2610篇 |
出版年
2024年 | 28篇 |
2023年 | 258篇 |
2022年 | 386篇 |
2021年 | 671篇 |
2020年 | 465篇 |
2019年 | 561篇 |
2018年 | 688篇 |
2017年 | 682篇 |
2016年 | 816篇 |
2015年 | 689篇 |
2014年 | 1002篇 |
2013年 | 1531篇 |
2012年 | 1357篇 |
2011年 | 1718篇 |
2010年 | 1307篇 |
2009年 | 1353篇 |
2008年 | 1292篇 |
2007年 | 1007篇 |
2006年 | 876篇 |
2005年 | 784篇 |
2004年 | 729篇 |
2003年 | 666篇 |
2002年 | 646篇 |
2001年 | 530篇 |
2000年 | 466篇 |
1999年 | 457篇 |
1998年 | 695篇 |
1997年 | 480篇 |
1996年 | 366篇 |
1995年 | 268篇 |
1994年 | 236篇 |
1993年 | 178篇 |
1992年 | 129篇 |
1991年 | 124篇 |
1990年 | 112篇 |
1989年 | 124篇 |
1988年 | 72篇 |
1987年 | 94篇 |
1986年 | 70篇 |
1985年 | 66篇 |
1984年 | 46篇 |
1983年 | 37篇 |
1982年 | 17篇 |
1981年 | 30篇 |
1980年 | 23篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 22篇 |
1976年 | 34篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
991.
Jin Hyuck Heo Dae Ho Song Basavaraj Rudragouda Patil Sang Hyuk Im 《Israel journal of chemistry》2015,55(9):966-977
Recently, innovative perovskite hybrid solar cells have attracted great interest in solar cell research fields, such as dye-sensitized solar cells, organic photovoltaics, thin-film solar cells, and silicon solar cells, because their device efficiencies are gradually approaching those of crystalline Si solar cells, and they can be fabricated by cheap low-temperature solution processes. Here, we review the recent progress of innovative perovskite hybrid solar cells. The introduction includes the general concerns about solar cells and why we need innovative solar cells. The second part explains the structure and the material properties of hybrid perovskite materials. We focus on why the hybrid perovskite materials can exhibit excellent solar cell properties, such as high open-circuit voltage. The third part introduces recent progress in innovative perovskite hybrid solar cells, in terms of device architecture and deposition methods for dense perovskite thin films with full surface coverage. The device architecture is important in attaining high power conversion efficiency; the device operating mechanism is dependent on the device structure; and the pinhole-free dense perovskite thin films with full surface coverage are crucial for achieving high efficiency. Finally, we summarize the recent progress in perovskite hybrid solar cells, and the issues to be solved, in the summary and outlook section. 相似文献
992.
The Effects of Annealing Atmosphere on the Electrical Properties of MgNb2O6/ITO Heterostructures
下载免费PDF全文
![点击此处可从《Journal of the American Ceramic Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yi‐Da Ho Kung‐Rong Chen Pei‐Ching Yu Cheng‐Liang Huang 《Journal of the American Ceramic Society》2015,98(2):580-586
The effects of annealing atmosphere (N2, air and O2) on the electrical properties of sol–gel‐derived MgNb2O6/ITO heterostructures are discussed in this work. All samples exhibited the amorphous phase and were highly transparent. The percentage of Nb4+ content increased when the films were annealed in the oxygen‐deficient conditions, which could lead to semiconducting films. In addition, the results show that the electrical properties of sol–gel‐derived MgNb2O6 thin films could be tuned based on the annealing atmosphere. Moreover, the conduction mechanisms of MgNb2O6/ITO heterostructures are also discussed in this study. The results show that MgNb2O6 thin films have potential for use in multifunctional optoelectronic applications, due to their flexible electrical properties and good transparency. 相似文献
993.
Chang Won Ahn Hee Sung Kim Won Seok Woo Sung Sik Won Hae Jin Seog Song A Chae Bong Chan Park Ki Bong Jang Yun Po Ok Hyon Ho Chong Ill Won Kim 《Journal of the American Ceramic Society》2015,98(6):1877-1883
We investigated the influence of CuO amount (0.5–3.0 mol%), sintering temperature (900°C–1000°C), and sintering time (2–6 h) on the low‐temperature sintering behavior of CuO‐added Bi0.5(Na0.78K0.22)0.5TiO3 (BNKT22) ceramics. Normalized strain (Smax/Emax), piezoelectric coefficient (d33), and remanent polarization (Pr) of 1.0 mol% CuO‐added BNKT22 ceramics sintered at 950°C for 4 h was 280 pm/V, 180 pC/N, and 28 μC/cm2, respectively. These values are similar to those of pure BNKT22 ceramics sintered at 1150°C. In addition, we investigated the performance of multilayer ceramic actuators made from CuO‐added BNKT22 in acoustic sound speaker devices. A prototype sound speaker device showed similar output sound pressure levels as a Pb(Zr,Ti)O3‐based device in the frequency range 0.66–20 kHz. This result highlights the feasibility of using low‐cost multilayer ceramic devices made of lead‐free BNKT‐based piezoelectric materials in sound speaker devices. 相似文献
994.
Design and verification of a single slab RAS through mass production of glass/MWNT added epoxy composite prepreg
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jae‐Hwan Shin Hong‐Kyu Jang Won‐Ho Choi Tae‐Hoon Song Chun‐Gon Kim Woo‐Yong Lee 《应用聚合物科学杂志》2015,132(22)
In this study, glass fiber composite prepreg is manufactured with multi‐walled carbon nanotube (MWNT) added epoxy using two different methods. Because MWNT agglomeration occurs, the calendering dispersion method is used to resolve this problem. The tensile and shear tests of glass/MWNT 1.8wt % added epoxy composite (CNT18) are conducted and the results are compared with the properties of a commercial glass/epoxy composite (GEP 118). The complex permittivity is measured using a network analyzer and a waveguide in the Ku‐band. A single slab radar absorbing structure (RAS) is also designed and verified. It is found that the tensile and shear properties of CNT18 are sufficient to replace GEP 118 as a structural material. Furthermore, the—10 dB bandwidth and reflection loss of the RAS using CNT18 is 12.87 to 17.78 GHz (4.91 GHz) and—29.2 dB at 14.95 GHz, respectively. The measurement results align well with the simulation results. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42019. 相似文献
995.
The effect of BMP‐2 and VEGF loading of gelatin‐pectin‐BCP scaffolds to enhance osteoblast proliferation
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A composite scaffold of gelatine (Gel)‐pectin (Pec)‐biphasic calcium phosphate (BCP) was successfully fabricated. Growth factors such as bone morphogenetic protein‐2 (BMP‐2) and vascular endothelial growth factor (VEGF) were loaded into the Gel‐Pec‐BCP hydrogel scaffolds by freeze‐drying. The surface morphology was investigated by scanning electron microscopy, and BCP dispersion in the hydrogel scaffolds was measured by energy dispersive and X‐ray diffraction spectroscopy. The results obtained from Fourier transform infrared spectroscopy and quantitative measurements showed successfully loading of BMP‐2 and VEGF into the Gel‐Pec‐BCP hydrogel scaffolds. In addition MC3T3‐E1 preosteoblasts were cultivated on the three types of scaffolds to investigate the effects of BMP‐2 and VEGF on cell viability and proliferation. The Gel‐Pec‐BCP scaffolds loaded with VEGF and BMP‐2 demonstrated more cell spreading and proliferation compared to those of the Gel‐Pec‐BCP scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41241. 相似文献
996.
997.
High Charge‐Carrier Mobility of 2.5 cm2 V−1 s−1 from a Water‐Borne Colloid of a Polymeric Semiconductor via Smart Surfactant Engineering
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
998.
999.
Self‐Crack‐Filled Graphene Films by Metallic Nanoparticles for High‐Performance Graphene Heterojunction Solar Cells
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1000.
Fluoro‐Substituted n‐Type Conjugated Polymers for Additive‐Free All‐Polymer Bulk Heterojunction Solar Cells with High Power Conversion Efficiency of 6.71%
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)