全文获取类型
收费全文 | 37897篇 |
免费 | 3519篇 |
国内免费 | 2091篇 |
专业分类
电工技术 | 4130篇 |
技术理论 | 2篇 |
综合类 | 3663篇 |
化学工业 | 4931篇 |
金属工艺 | 1326篇 |
机械仪表 | 2031篇 |
建筑科学 | 4328篇 |
矿业工程 | 1786篇 |
能源动力 | 1519篇 |
轻工业 | 2502篇 |
水利工程 | 1529篇 |
石油天然气 | 3035篇 |
武器工业 | 274篇 |
无线电 | 2476篇 |
一般工业技术 | 3565篇 |
冶金工业 | 2533篇 |
原子能技术 | 711篇 |
自动化技术 | 3166篇 |
出版年
2024年 | 136篇 |
2023年 | 441篇 |
2022年 | 1092篇 |
2021年 | 1329篇 |
2020年 | 1177篇 |
2019年 | 866篇 |
2018年 | 887篇 |
2017年 | 1023篇 |
2016年 | 1270篇 |
2015年 | 1367篇 |
2014年 | 2381篇 |
2013年 | 2347篇 |
2012年 | 2809篇 |
2011年 | 3097篇 |
2010年 | 2287篇 |
2009年 | 2282篇 |
2008年 | 2071篇 |
2007年 | 2549篇 |
2006年 | 2277篇 |
2005年 | 2024篇 |
2004年 | 1675篇 |
2003年 | 1450篇 |
2002年 | 1246篇 |
2001年 | 1042篇 |
2000年 | 854篇 |
1999年 | 676篇 |
1998年 | 537篇 |
1997年 | 450篇 |
1996年 | 397篇 |
1995年 | 294篇 |
1994年 | 241篇 |
1993年 | 151篇 |
1992年 | 139篇 |
1991年 | 99篇 |
1990年 | 103篇 |
1989年 | 88篇 |
1988年 | 89篇 |
1987年 | 41篇 |
1986年 | 25篇 |
1985年 | 21篇 |
1984年 | 27篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1964年 | 12篇 |
1961年 | 8篇 |
1960年 | 9篇 |
1959年 | 8篇 |
1955年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Chunsheng Wang Yishuang Wang Mingqiang Chen Defang Liang Zhonglian Yang Wen Cheng Zhiyuan Tang Jun Wang Han Zhang 《International Journal of Hydrogen Energy》2021,46(7):5852-5874
Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process. 相似文献
2.
3.
Bin Feng Xin Jiang Guisheng Zou Wengan Wang Tianming Sun Heng Yang Guanlei Zhao Mingye Dong Yu Xiao Hongwei Zhu Lei Liu 《Advanced functional materials》2021,31(29):2102359
The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering. 相似文献
4.
《Ceramics International》2022,48(6):7593-7604
The ceramic core, produced by hot injection molding, is one of the critical components for manufacturing high-performance aircraft engine turbine blades. However, the injection molding process will cause defects such as burrs and flashes in the fine structure of the formed ceramic core. Manual trimming is necessary, but the trimming quality is poor, and the yield is low. In this paper, the online trimming method of ceramic cores is studied. Based on the orthogonal experiment method, the optimal laser parameters for processing the ceramic core's porous multi-scale particle structure material were obtained. Further, the problems of the match head and tail phenomenon and dimensional accuracy improvement in trimming ceramic cores have been studied. A path optimisation method is proposed to improve the quality and accuracy of the trimming profile effectively. Finally, the overall process flow of ceramic core trimming is elaborated, and experimental verification is given. The results show that the ceramic core online trimming method proposed in this paper has advantages of high precision and high yield compared with the manual method, which will have substantial potential application value in the aviation field. 相似文献
5.
6.
Dr. Tomasz Ratajczyk Prof. Dr. Gerd Buntkowsky Dr. Torsten Gutmann Dr. Bartłomiej Fedorczyk Dr. Adam Mames Dr. Mariusz Pietrzak Zuzanna Puzio Piotr Grzegorz Szkudlarek 《Chembiochem : a European journal of chemical biology》2021,22(5):855-860
The biorelevant PyFALGEA oligopeptide ligand, which is selective towards the epidermal growth factor receptor (EGFR), has been successfully employed as a substrate in magnetic resonance signal amplification by reversible exchange (SABRE) experiments. It is demonstrated that PyFALGEA and the iridium catalyst IMes form a PyFALGEA:IMes molecular complex. The interaction between PyFALGEA:IMes and H2 results in a ternary SABRE complex. Selective 1D EXSY experiments reveal that this complex is labile, which is an essential condition for successful hyperpolarization by SABRE. Polarization transfer from parahydrogen to PyFALGEA is observed leading to significant enhancement of the 1H NMR signals of PyFALGEA. Different iridium catalysts and peptides are inspected to discuss the influence of their molecular structures on the efficiency of hyperpolarization. It is observed that PyFALGEA oligopeptide hyperpolarization is more efficient when an iridium catalyst with a sterically less demanding NHC ligand system such as IMesBn is employed. Experiments with shorter analogues of PyFALGEA, that is, PyLGEA and PyEA, show that the bulky phenylalanine from the PyFALGEA oligopeptide causes steric hindrance in the SABRE complex, which hampers hyperpolarization with IMes. Finally, a single-scan 1H NMR SABRE experiment of PyFALGEA with IMesBn revealed a unique pattern of NMR lines in the hydride region, which can be treated as a fingerprint of this important oligopeptide. 相似文献
7.
8.
9.
10.
Dr. Alejandra A. Carriles Alberto Mills Dr. María-José Muñoz-Alonso Dr. Dolores Gutiérrez Dr. Juan M. Domínguez Prof. Dr. Juan A. Hermoso Prof. Dr. Federico Gago 《Chembiochem : a European journal of chemical biology》2021,22(2):374-391
Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the “canonical” one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades. 相似文献