全文获取类型
收费全文 | 3320篇 |
免费 | 84篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 128篇 |
综合类 | 7篇 |
化学工业 | 670篇 |
金属工艺 | 73篇 |
机械仪表 | 53篇 |
建筑科学 | 58篇 |
矿业工程 | 3篇 |
能源动力 | 98篇 |
轻工业 | 236篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 403篇 |
一般工业技术 | 466篇 |
冶金工业 | 897篇 |
原子能技术 | 51篇 |
自动化技术 | 254篇 |
出版年
2023年 | 20篇 |
2022年 | 36篇 |
2021年 | 63篇 |
2020年 | 27篇 |
2019年 | 29篇 |
2018年 | 48篇 |
2017年 | 37篇 |
2016年 | 50篇 |
2015年 | 39篇 |
2014年 | 83篇 |
2013年 | 129篇 |
2012年 | 116篇 |
2011年 | 128篇 |
2010年 | 98篇 |
2009年 | 105篇 |
2008年 | 124篇 |
2007年 | 109篇 |
2006年 | 84篇 |
2005年 | 104篇 |
2004年 | 73篇 |
2003年 | 94篇 |
2002年 | 74篇 |
2001年 | 74篇 |
2000年 | 68篇 |
1999年 | 79篇 |
1998年 | 367篇 |
1997年 | 205篇 |
1996年 | 133篇 |
1995年 | 95篇 |
1994年 | 88篇 |
1993年 | 80篇 |
1992年 | 36篇 |
1991年 | 38篇 |
1990年 | 28篇 |
1989年 | 47篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 29篇 |
1985年 | 24篇 |
1984年 | 27篇 |
1983年 | 25篇 |
1982年 | 19篇 |
1981年 | 26篇 |
1980年 | 20篇 |
1979年 | 24篇 |
1978年 | 25篇 |
1977年 | 30篇 |
1976年 | 47篇 |
1974年 | 14篇 |
1973年 | 9篇 |
排序方式: 共有3406条查询结果,搜索用时 15 毫秒
91.
92.
Maksudul M. Alam Osamu Ito Naoki Sakurar Hiroshi Moriyama 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):1007-1024
Abstract Efficient electron-transfer reactions from three kind of tetraselenafulvalenes (TSeF's) to photoexcited triplet state of C60 or C70 in polar solvents have been confirmed by transient absorption spectroscopy observing the decay of 3C60*/3C70* and rise of C60 ??/C70 ??. Growth of single crystal seems to be stimulated by laser irradiation of the solution containing C60 and bis(ethylenedithio)tetraselena-fulvalene (BEDT-TSeF), in which C60 ?? was effectively formed. 相似文献
93.
94.
Katsuhiro Inomata Tamiko Terahama Rena Sekoguchi Tatsunori Ito Hideki Sugimoto Eiji Nakanishi 《Polymer》2012,53(15):3281-3286
Polypeptide hydrogels were prepared by cross-linking of hydrophobically-modified poly[N5-(2-hydroxyethyl) l-glutamine] having alkyl side chains –CnH2n+1. Chain length of the alkyl group was n = 8, 16, and 18, and their mole fractions in the polypeptide were varied in the range of 0.05–0.16. Shape memory ability of the prepared polypeptide hydrogels was investigated. After deformation at 60 °C, the hydrogel was cooled in order to fix the temporary deformed shape. It was found that crystallization of the alkyl side chains did not occur, and the fixation ability of the hydrogel at 0 °C was low. In the subsequent heating process, the deformed temporary shape spontaneously recovered to the original shape gradually with increasing temperature, in other words, the shape recovery ratio varied with depending on the recovery temperature. From these observations, it was proposed that the shape fixation of the polypeptide hydrogel was achieved by strong segregation of the hydrophobic alkyl chains at low temperature, and the shape recovery of the deformed hydrogel was accompanied by the gradual decrease of the segregation strength with the temperature increase. 相似文献
95.
In this study, we focus on the intelligent behavior of an octopus and describe the development of a flexible manipulator. To realize the intelligent behavior, we employ sponges, rubbers and wires instead of electrical computers. The manipulator is controlled by the dynamics of the body such as the flexibility of the sponges, resilience of the rubbers and constraint by the wires. To demonstrate the effectiveness of the proposed manipulator, we conducted experiment for grasping various objects. We confirmed that grasping behaviors similar to those of an octopus can be realized by the dynamics of the body without electrical computers. 相似文献
96.
Hidemine Obara Masamu Kamaga Takumi Ito Yukihiko Sato 《Electrical Engineering in Japan》2014,186(4):81-91
Multilevel converters can essentially reduce harmonics even when their switching frequency is low. Among the various topologies of the multilevel converters, flying capacitor converters are considered to be promising converters for realizing high power density. However, the main circuit of the flying capacitor converters has many capacitors. Therefore, in this study, the volume of the capacitors in the flying capacitor converters is determined by taking into consideration the allowable ripple voltage and temperature rise in the capacitor. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 81–91, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22361 相似文献
97.
Genichi Shigesato Taishi Fujishiro Takuya Hara 《Metallurgical and Materials Transactions A》2014,45(4):1876-1882
The boron concentration profiles around prior austenite grain boundaries in Fe-0.05C-0.5Mo-0.001B (mass pct) are examined using aberration-corrected STEM-EELS. In order to obtain the precise distribution of boron around the boundaries, tilt series measurements with thin specimens (<30 nm) are performed and the EEL spectra are analyzed by principal component analysis (PCA) and multivariate curve resolution (MCR). The boron concentration profile changes with the cooling rate from the solid solution temperature. The concentration at grain boundaries is maximized at a medium rate (30 °C/s), where the concentration reaches 8 at. pct, and it decreases at a larger (250 °C/s) or smaller (5 °C/s) rate. On the other hand, the boron distribution becomes wider as the cooling rate becomes smaller. The current results suggest that the boron segregation in the alloy is formed by the “non-equilibrium segregation mechanism.” 相似文献
98.
99.
Anat Akiva Johanna Melke Sana Ansari Nalan Liv Robin van der Meijden Merijn van Erp Feihu Zhao Merula Stout Wouter H. Nijhuis Cilia de Heus Claudia Muñiz Ortera Job Fermie Judith Klumperman Keita Ito Nico Sommerdijk Sandra Hofmann 《Advanced functional materials》2021,31(17):2010524
Bone formation (osteogenesis) is a complex process in which cellular differentiation and the generation of a mineralized organic matrix are synchronized to produce a hybrid hierarchical architecture. To study the mechanisms of osteogenesis in health and disease, there is a great need for functional model systems that capture in parallel, both cellular and matrix formation processes. Stem cell-based organoids are promising as functional, self-organizing 3D in vitro models for studying the physiology and pathology of various tissues. However, for human bone, no such functional model system is yet available. This study reports the in vitro differentiation of human bone marrow stromal cells into a functional 3D self-organizing co-culture of osteoblasts and osteocytes, creating an organoid for early stage bone (woven bone) formation. It demonstrates the formation of an organoid where osteocytes are embedded within the collagen matrix that is produced by the osteoblasts and mineralized under biological control. Alike in in vivo osteocytes, the embedded osteocytes show network formation and communication via expression of sclerostin. The current system forms the most complete 3D living in vitro model system to investigate osteogenesis, both in physiological and pathological situations, as well as under the influence of external triggers (mechanical stimulation, drug administration). 相似文献