全文获取类型
收费全文 | 1918篇 |
免费 | 38篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 112篇 |
综合类 | 7篇 |
化学工业 | 369篇 |
金属工艺 | 36篇 |
机械仪表 | 57篇 |
建筑科学 | 39篇 |
能源动力 | 108篇 |
轻工业 | 128篇 |
水利工程 | 12篇 |
石油天然气 | 1篇 |
无线电 | 170篇 |
一般工业技术 | 309篇 |
冶金工业 | 369篇 |
原子能技术 | 74篇 |
自动化技术 | 168篇 |
出版年
2023年 | 6篇 |
2022年 | 25篇 |
2021年 | 24篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 34篇 |
2015年 | 24篇 |
2014年 | 43篇 |
2013年 | 83篇 |
2012年 | 62篇 |
2011年 | 87篇 |
2010年 | 61篇 |
2009年 | 77篇 |
2008年 | 91篇 |
2007年 | 74篇 |
2006年 | 62篇 |
2005年 | 68篇 |
2004年 | 82篇 |
2003年 | 80篇 |
2002年 | 50篇 |
2001年 | 53篇 |
2000年 | 41篇 |
1999年 | 49篇 |
1998年 | 152篇 |
1997年 | 115篇 |
1996年 | 78篇 |
1995年 | 43篇 |
1994年 | 35篇 |
1993年 | 28篇 |
1992年 | 25篇 |
1991年 | 24篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 22篇 |
1987年 | 14篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 13篇 |
1974年 | 5篇 |
1972年 | 3篇 |
排序方式: 共有1959条查询结果,搜索用时 359 毫秒
41.
Masanori Yamazaki Akiko Nishijima Kazuko Ikeda Shoji Ichihara 《Polymer Bulletin》2004,52(3-4):267-274
Summary
In order to obtain materials with nanopores which will be applicable for many fields, the structures of the cured blends of phenolic resin (PhN), poly(methyl methacrylate) (PMMA) and curing agent were studied. After PMMA was extracted from cured blends, the structures of cured phenolic resins were observed with SEM. As a results, it was found that nanosized continuous pore structures were formed in extremely wide composition region if curing temperature was high. 相似文献
42.
Masanori Yamada 《Electrochimica acta》2003,48(17):2411-2415
In recent years, a lot of attentions have been paid for a development of water-free polymer electrolyte membranes fuel cells (PEMFC) at intermediate temperatures (above 100 °C) because of many technological advantages of higher temperature operation. However, the proton conductivity of conventional polymer membranes under water-free condition is usually very low and the polymeric membranes are not stable at higher temperatures. So, the development of non-hydrous proton conducting membrane under water-free condition has been a state of the art issue in the advanced PEMFC technology. In this study, non-hydrous protonic conducting material was prepared by the mixing of acidic surfactant of mono-dodecylphosphate (MDP) and organic base of benzimidazole (BnIm). The proton conductivity and thermal stability of MDP-BnIm mixed material increased with the mixing ratio of BnIm. Maximum proton conductivity of MDP-BnIm mixed material (BnIm mixing ratio of 200 wt.%. vs. MDP) was found to be 1×10−3 S cm−1 at 150 °C under water-free condition. 相似文献
43.
K. Wakui K. Satoh G. Sawada K. Shiozawa K. Matano K. Suzuki T. Hayakawa Y. Yoshimura K. Murata F. Mizukami 《Catalysis Letters》2002,81(1-2):83-88
Dehydrogenative cracking reaction of n-butane was studied using HZSM-5 catalyst modified with various metal oxides. Alkaline earth (magnesium), transition metal (cobalt) and rare earth (lanthanum) elements are used for the modification. The selectivity of the products was studied at low conversion (20%). Methane, ethane, ethylene, propylene, butenes and butadiene were the main products. With the use of the cobalt- or magnesium-containing HZSM-5, dehydrogenative cracking was observed and the selectivity of ethylene was much larger than that of ethane. On the other hand, the selectivity of ethylene and ethane were almost the same in the reaction using the lanthanum-containing HZSM-5. It is considered that the cobalt- and magnesium-loaded sites on HZSM-5 played an important role in the dehydrogenative cracking. 相似文献
44.
Hideaki Adachi Toshifumi Satoh Masahiro Sakai Koichi Mizuno Kentaro Setsune 《Journal of Superconductivity》1994,7(4):737-741
Epitaxial multilayer thin films of infinite-layer (Sr, Ca)CuO2 and perovskite (Sr, Ca)RuO3 have been prepared on (100) SrTiO3 substrates by multitarget rf magnetron sputtering. X-ray diffraction analyses revealed that the multilayer structure of (Sr, Ca)CuO3/(Sr, Ca)RuO3 was successfully fabricated with a minimum layer thickness of 20 Å. Transmission electron microscopy measurements of the multilayers indicated that there was no dislocation which normally exists in single-layer films with an infinite-layer structure. Resistivities of multilayer films at room temperature ranged from 1 to 10 m cm and showed semiconductor-like dependence against the temperature. 相似文献
45.
Using Bogoliubov-de Gennes equation, we study quasiparticle excitations in layered superconductors in the presence of a straight vortex line which is parallel to the layers. The lowest bound state is shown to have energy eigenvalue of the order of magnitude , the energy gap, in contrast to the corresponding value 2/EF when the line is perpendicular to the layers. 相似文献
46.
Yuki Akinaga Tokuhisa Kawawaki Hinano Kameko Yuki Yamazaki Kenji Yamazaki Yuhi Nakayasu Kosaku Kato Yuto Tanaka Adie Tri Hanindriyo Makito Takagi Tomomi Shimazaki Masanori Tachikawa Akira Yamakata Yuichi Negishi 《Advanced functional materials》2023,33(33):2303321
Single-atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H2) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g-C3N4; i.e., gCN), a promising visible-light-driven photocatalyst. A method is established to prepare SA-loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H2-evolution activity of the prepared metal SA-loaded gCN reveals that Pd, Pt, and Rh SA-loaded gCN exhibits relatively high H2-evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA-loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H2-evolution efficiency per SA than other metal SA-loaded gCN. Finally, the 8.6 times higher H2-evolution rate per active site of Pd SA is achieved than that of Pd-nanoparticles cocatalyst. 相似文献
47.
H Toyoshima S Hayashi N Tanabe K Miyanishi T Satoh Y Aizawa T Izumi 《Canadian Metallurgical Quarterly》1996,59(3-4):81-95
Epidemiological features, risk factors and preventive methods of sudden death (SD) derived from studies the authors have performed since 1987 together with colleagues in Niigata University School of Medicine were reviewed. When SD was defined as death occurring within 24 hours of the onset of symptoms, the annual incidence was 145/100,000 for people aged 15 years and older in Niigata Prefecture. The incidence increased sharply along with the advance of age, while the proportion of SD to natural death due to circulatory diseases was higher in younger people. Though diseases of the circulatory system made up approximately 90 percent of all causes of death, SD due to ischemic heart disease was less frequent in Japan than in western countries. SD showed various patterns in seasonal and "within-a-day" occurrences according to sex, age and cause of death. The months of the highest SD occurrence differed by occupation and matched the busiest work periods. A decrease in sleeping hours and mental stress experienced during the preceding week were related to the occurrence of both sudden death and non-fatal acute myocardial infarction. People having structural circulatory diseases were shown to be predisposed to SD when stress occurred, because fatal arrhythmia is easily induced by the above factors in such people. Health examinations were shown to have preventive effects, though limited, against SD. Differences in the resuscitated rates in cases where a witness was present and where one was not indicates that educating people about correct resuscitation methods is important to minimizing SD. 相似文献
48.
Tiago?OliveiraEmail author Ken?Satoh Paulo?Novais José?Neves Hiroshi?Hosobe 《Autonomous Agents and Multi-Agent Systems》2017,31(3):656-695
In this work a default revision mechanism is introduced into speculative computation to manage incomplete information. The default revision is supported by a method for the generation of default constraints based on Bayesian networks. The method enables the generation of an initial set of defaults which is used to produce the most likely scenarios during the computation, represented by active processes. As facts arrive, the Bayesian network is used to derive new defaults. The objective with such a new dynamic mechanism is to keep the active processes coherent with arrived facts. This is achieved by changing the initial set of default constraints during the reasoning process in speculative computation. A practical example in clinical decision support is described. 相似文献
49.
Xinyue Zhao Author Vitae Yutaka Satoh Author Vitae Author Vitae Shun’ichi Kaneko Author Vitae Author Vitae Ryushi Ozaki Author Vitae 《Pattern recognition》2011,44(6):1296-1311
In this paper, we propose a robust and accurate background model, called grayscale arranging pairs (GAP). The model is based on the statistical reach feature (SRF), which is defined as a set of statistical pair-wise features. Using the GAP model, moving objects are successfully detected under a variety of complex environmental conditions. The main concept of the proposed method is the use of multiple point pairs that exhibit a stable statistical intensity relationship as a background model. The intensity difference between pixels of the pair is much more stable than the intensity of a single pixel, especially in varying environments. Our proposed method focuses more on the history of global spatial correlations between pixels than on the history of any given pixel or local spatial correlations. Furthermore, we clarify how to reduce the GAP modeling time and present experimental results comparing GAP with existing object detection methods, demonstrating that superior object detection with higher precision and recall rates is achieved by GAP. 相似文献
50.
In this article, we review the growth of AROB conferences, and assess the various contributions, which have covered digital
life, the artificial brain, artificial society, and evolutionary robots, etc. We analyze the relations between artificial
life, complexity, and intelligent robots, and finally give our view of the expected future of AROB.
This work was presented in part at the 5th International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28,
2000 相似文献