全文获取类型
收费全文 | 9267篇 |
免费 | 1031篇 |
国内免费 | 239篇 |
专业分类
电工技术 | 106篇 |
综合类 | 741篇 |
化学工业 | 1114篇 |
金属工艺 | 334篇 |
机械仪表 | 303篇 |
建筑科学 | 2049篇 |
矿业工程 | 97篇 |
能源动力 | 152篇 |
轻工业 | 104篇 |
水利工程 | 205篇 |
石油天然气 | 89篇 |
武器工业 | 23篇 |
无线电 | 950篇 |
一般工业技术 | 2409篇 |
冶金工业 | 623篇 |
原子能技术 | 31篇 |
自动化技术 | 1207篇 |
出版年
2023年 | 353篇 |
2022年 | 127篇 |
2021年 | 259篇 |
2020年 | 300篇 |
2019年 | 296篇 |
2018年 | 282篇 |
2017年 | 253篇 |
2016年 | 318篇 |
2015年 | 350篇 |
2014年 | 467篇 |
2013年 | 557篇 |
2012年 | 562篇 |
2011年 | 666篇 |
2010年 | 518篇 |
2009年 | 543篇 |
2008年 | 514篇 |
2007年 | 534篇 |
2006年 | 517篇 |
2005年 | 462篇 |
2004年 | 403篇 |
2003年 | 331篇 |
2002年 | 298篇 |
2001年 | 187篇 |
2000年 | 167篇 |
1999年 | 167篇 |
1998年 | 158篇 |
1997年 | 105篇 |
1996年 | 107篇 |
1995年 | 97篇 |
1994年 | 97篇 |
1993年 | 68篇 |
1992年 | 73篇 |
1991年 | 48篇 |
1990年 | 59篇 |
1989年 | 35篇 |
1988年 | 29篇 |
1987年 | 25篇 |
1986年 | 15篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 29篇 |
1982年 | 20篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 82 毫秒
1.
2.
Wenyan Ma Lian-Wei Luo Peihua Dong Peiyun Zheng Xiuhua Huang Chong Zhang Jia-Xing Jiang Yong Cao 《Advanced functional materials》2021,31(45):2105027
Recent studies have demonstrated that dihydrophenazine (Pz) with high redox-reversibility and high theoretical capacity is an attractive building block to construct p-type polymer cathodes for dual-ion batteries. However, most reported Pz-based polymer cathodes to date still suffer from low redox activity, slow kinetics, and short cycling life. Herein, a donor–acceptor (D–A) Pz-based conjugated microporous polymer (TzPz) cathode is constructed by integrating the electron-donating Pz unit and the electron-withdrawing 2,4,6-triphenyl-1,3,5-triazine (Tz) unit into a polymer chain. The D–A type structure enhances the polymer conjugation degree and decreases the band gap of TzPz, facilitating electron transportation along the polymer skeletons. Therefore the TzPz cathode for dual-ion battery shows a high reversible capacity of 192 mAh g−1 at 0.2 A g−1 with excellent rate performance (108 mAh g−1 at 30 A g−1), which is much higher than that of its counterpart polymer BzPz produced from 1,3,5-triphenylbenzene (Bz) and Pz (148 and 44 mAh g−1 at 0.2 and 10 A g−1, respectively). More importantly, the TzPz cathode also shows a long and stable cyclability of more than 10 000 cycles. These results demonstrate that the D–A structural design is an efficient strategy for developing high-performance polymer cathodes for dual-ion batteries. 相似文献
3.
4.
Dr. Daniel Feder Dr. Siti H. Mohd-Pahmi Dr. Waleed M. Hussein Prof. Luke W. Guddat Prof. Ross P. McGeary Prof. Gerhard Schenk 《ChemMedChem》2021,16(21):3342-3359
Metallohydrolases form a large group of enzymes that have fundamental importance in a broad range of biological functions. Among them, the purple acid phosphatases (PAPs) have gained attention due to their crucial role in the acquisition and use of phosphate by plants and also as a promising target for novel treatments of bone-related disorders and cancer. To date, no crystal structure of a mammalian PAP with drug-like molecules bound near the active site is available. Herein, we used a fragment-based design approach using structures of a mammalian PAP in complex with the MaybridgeTM fragment CC063346, the amino acid L-glutamine and the buffer molecule HEPES, as well as various solvent molecules to guide the design of highly potent and efficient mammalian PAP inhibitors. These inhibitors have improved aqueous solubility when compared to the clinically most promising PAP inhibitors available to date. Furthermore, drug-like fragments bound in newly discovered binding sites mapped out additional scaffolds for further inhibitor discovery, as well as scaffolds for the design of inhibitors with novel modes of action. 相似文献
5.
A carbon-containing CoCrFeNi high entropy alloy (HEA) with heterogeneous structures was obtained through thermome-chanical treatments,which induced concurrent recrystallization and carbide precipitation in the alloy.A combination of high yield strength (556 MPa) and large uniform elongation (45%) was achieved in the investigated alloy.The enhancement of the strength is attributed to the combined effects of grain refinement,precipitation strengthening and microstructural het-erogeneity.Our work demonstrated that the heterogeneity design could be realized by thermomechanical processes,which provided a practical strategy for producing HEAs with high performance. 相似文献
6.
Young Been Kim Sung Hyeon Jung Dong Su Kim Nishad G. Deshpande Hee Won Suh Hak Hyeon Lee Ji Hoon Choi Ho Seong Lee Hyung Koun Cho 《Advanced functional materials》2021,31(38):2102439
Antimony triselenide (Sb2Se3) nanoflake-based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations. 相似文献
7.
Additive manufacturing,quasi-static and dynamic compressive behaviours of ceramic lattice structures
《Journal of the European Ceramic Society》2022,42(15):7102-7112
Ceramic lattice structures (CLSs) are used for construction in common and extreme environments because of the extraordinary properties of ceramics. In this study, we designed and additively manufactured CLSs with distinct structural parameters to explore their quasi-static and dynamic compressive behaviours in detail. It was demonstrated that both the relative density (?ρ) and inclination angle (ω) had a significant impact on the quasi-static and dynamic mechanical properties of the CLSs. Furthermore, the mathematical relationships between the quasi-static compressive properties, including quasi-static compressive strength (QS), quasi-static Young’s modulus (QY), and quasi-static energy absorption (QE), versus ?ρ and ω obeyed the Gibson–Ashby and Deshpande and Fleck models, respectively. It was revealed by experiment and simulation that as the stiffness increased, the quasi-static failure mode of the CLSs changed from a parallel-vertical-inclined mixed mode to a parallel-vertical mode. In addition, the relationship between the dynamic mechanical properties of the CLSs versus ?ρ and ω also followed the Gibson–Ashby and Deshpande and Fleck models. The exceptional dynamic increase factor indicated that CLSs are highly suitable for extreme environments. These findings will aid in the research and development of customised additively manufactured CLSs. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(100):41994-42000
Hydrogen technology is widely considered a novel clean energy source, and electrolysis is an effective method for hydrogen evolution. Therefore, efficient hydrogen evolution reaction (HER) catalysts are urgently needed to replace precious metal catalysts and meet ecological and environmental protection standards. Herein, Ni–Mn–P electrocatalysts are synthesized using facile electrodeposition technology. The influence of the Mn addition on the catalytic behavior is studied by the comprehensive analysis of catalytic performance and morphology of the catalysts. Among them, the Ni–Mn–P0.01 catalyst exhibits small coral-like structures, greatly improving the adsorption and desorption of hydrogen ions and reducing the overpotential hydrogen evolution. Consequently, overpotential at 10 mA cm?2 electric current density is 113 mV, and the value of the Tafel slope achieves 74 mV/dec. Furthermore, the Ni–Mn–P catalyst shows long-time (20 h) stability at current densities of 10 and 60 mA/cm2. The results confirm that the synergistic effect of Ni, Mn, and P accelerates the electrochemical reaction. Meanwhile, the addition of manganese element can change the micromorphology of the catalyst, thereby exposing more active sites to participate in the reaction, enhancing water ionization, improving the catalytic performance. This study opens a new way toward improving the activity of the catalyst by adjusting Mn concentration during the electrodeposition process. 相似文献
9.
针对复杂系统中关键性能指标(KPI)相关故障检测方法检测精度低的问题,提出基于双层改进潜结构投影(DL-IPLS)的KPI相关故障检测方法. 利用协整分析和主元分析建立底层模型,对非平稳和平稳变量进行特征提取. 将提取的信息进行融合,建立改进潜结构投影的上层模型,根据融合信息对KPI的贡献进行空间分解. 在2个正交子空间中设计统计量,实现KPI相关故障的在线监测. 田纳西-伊斯曼过程和青霉素发酵过程的仿真结果表明,在面向工业平稳和非平稳复杂工业系统检测时,所提方法有效提高了KPI相关故障的检测率,降低了KPI无关故障的误报率. 相似文献
10.
Oleksandr Gryshkov Vitalii Mutsenko Dmytro Tarusin Diaa Khayyat Ortwin Naujok Ekaterina Riabchenko Yuliia Nemirovska Arseny Danilov Alexander Y. Petrenko Birgit Glasmacher 《International journal of molecular sciences》2021,22(6)
Alginate as a versatile naturally occurring biomaterial has found widespread use in the biomedical field due to its unique features such as biocompatibility and biodegradability. The ability of its semipermeable hydrogels to provide a favourable microenvironment for clinically relevant cells made alginate encapsulation a leading technology for immunoisolation, 3D culture, cryopreservation as well as cell and drug delivery. The aim of this work is the evaluation of structural properties and swelling behaviour of the core-shell capsules for the encapsulation of multipotent stromal cells (MSCs), their 3D culture and cryopreservation using slow freezing. The cells were encapsulated in core-shell capsules using coaxial electrospraying, cultured for 35 days and cryopreserved. Cell viability, metabolic activity and cell–cell interactions were analysed. Cryopreservation of MSCs-laden core-shell capsules was performed according to parameters pre-selected on cell-free capsules. The results suggest that core-shell capsules produced from the low viscosity high-G alginate are superior to high-M ones in terms of stability during in vitro culture, as well as to solid beads in terms of promoting formation of viable self-assembled cellular structures and maintenance of MSCs functionality on a long-term basis. The application of 0.3 M sucrose demonstrated a beneficial effect on the integrity of capsules and viability of formed 3D cell assemblies, as compared to 10% dimethyl sulfoxide (DMSO) alone. The proposed workflow from the preparation of core-shell capsules with self-assembled cellular structures to the cryopreservation appears to be a promising strategy for their off-the-shelf availability. 相似文献