全文获取类型
收费全文 | 1619篇 |
免费 | 51篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 1671篇 |
出版年
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 34篇 |
2020年 | 24篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 24篇 |
2016年 | 35篇 |
2015年 | 26篇 |
2014年 | 59篇 |
2013年 | 102篇 |
2012年 | 57篇 |
2011年 | 109篇 |
2010年 | 92篇 |
2009年 | 48篇 |
2008年 | 78篇 |
2007年 | 82篇 |
2006年 | 51篇 |
2005年 | 68篇 |
2004年 | 71篇 |
2003年 | 53篇 |
2002年 | 36篇 |
2001年 | 35篇 |
2000年 | 32篇 |
1999年 | 22篇 |
1998年 | 77篇 |
1997年 | 57篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 27篇 |
1993年 | 32篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1671条查询结果,搜索用时 15 毫秒
41.
42.
A DC (data center) demands air-conditioning power as large as the 1/3-1/2 of total electricity consumption. Thus, energy saving of cooling power of DC yields considerable effect on both economic and environmental views. PV (Photovoltaic) and absorption refrigerator with CGS (cogeneration systems) or gas boiler are possible power saving options. The waste warm air from DC would be utilized for greenhouse heating when DC and greenhouse locate near in the suburbs. In this study, the authors develop an energy network model to assess the potential contribution of DC as a major electric power and chilled air consumer as well as the warm air supplier in a district to the energy efficiency improvement. The evaporation heat of LNG (liquefied natural gas) utilization is also considered as well as PV, CGS. This model is applied to the cases of the urban area in Tokyo which involves athletic center, shops and hospital and the suburbs including greenhouse and then compared. 相似文献
43.
Mayu Iwata Hiroki Miyamoto Takahiro Hara Daijiro Komaki Kentaro Shimatani Tomohiro Mashita Kiyoshi Kiyokawa Toshiaki Uemukai Gen Hattori Shojiro Nishio Haruo Takemura 《Personal and Ubiquitous Computing》2013,17(5):1035-1050
People routinely carry mobile devices in their daily lives and obtain a variety of information from the Internet in many different situations. In searching for information (content) with a mobile device, a user’s activity (e.g., moving or stationary) and context (e.g., commuting in the morning or going downtown in the evening) often change, and such changes can affect the user’s degree of concentration on his or her mobile device’s display and information needs. Therefore, a search system should provide the user with an amount of information suitable for the current activity and a type of information suitable for the current context. In this study, we present the design and implementation of a content search system that considers a mobile user’s activity and context, with the goal of reducing the user’s operation load for content search. The proposed system switches between two kinds of content search systems according to the user’s activity: the location-based content search system is activated when the user is stationary (e.g., standing and sitting), while a menu-based content search system is activated when the user is moving (e.g., walking). Both systems present information according to user context. The location-based system presents detailed information via menus and a map according to location-based categories. The menu-based system presents only a few options to enable users to get content easily. Through user experiments, we confirmed that participants could get desired information more easily with this system than with a commercial search system. 相似文献
44.
Iwata 《Algorithmica》2008,36(4):331-341
Abstract. This paper presents a new algorithm for computing the maximum degree δ
k
(A) of a minor of order k in a matrix pencil A(s) . The problem is of practical significance in the field of numerical analysis and systems control.
The algorithm adopts a general framework of ``combinatorial relaxation' due to Murota. It first solves the weighted bipartite
matching problem to obtain an estimate
on δ
k
(A) , and then checks if the estimate is correct, exploiting the optimal dual solution. In case of incorrectness, it modifies
the matrix pencil A(s) to improve the estimate
without changing δ
k
(A) .
The present algorithm performs this matrix modification by an equivalence transformation with constant matrices, whereas
the previous one uses biproper rational function matrices. Thus the present approach saves memory space and reduces the running
time bound by a factor of rank A . 相似文献
45.
在全球的CDMA运营商中,日本KDDI是非常突出的一家。KDDI于2002年4月推出了自己的3G业务,采用的是cdma20001x技术。与NTTDoCoMo的3G业务一开始缓慢发展相比,KDDI虽晚半年推出3G业务,但其3G业务一起步就进入了快速发展阶段,业务开展才84天,用户数就突破百万大关。到2004年10月,用户数突破1600万的KDDI。那么,到底是什么使KDDI后来居上的呢?本文试图从分析KDDI的业务人手,破解KDDI的成功密码. 相似文献
46.
A technique for preparation of a pillar-shaped specimen and its multidirectional observation using a combination of a scanning transmission electron microscope (STEM) and a focused ion beam (FIB) instrument has been developed. The system employs an FIB/STEM compatible holder with a specially designed tilt mechanism, which allows the specimen to be tilted through 360 degrees [T. Yaguchi, M. Konno, T. Kamino, T. Hashimoto, T. Ohnishi, K. Umemura, K. Asayama, Microsc. Microanal. 9 (Suppl. 2) (2003) 118; T. Yaguchi, M. Konno, T. Kamino, T. Hashimoto, T. Ohnishi, M. Watanabe, Microsc. Microanal. 10 (Suppl. 2) (2004) 1030]. This technique was applied to obtain the three-dimensional (3D) elemental distributions around a contact plug of a Si device used in a 90-nm technology. A specimen containing only one contact plug was prepared in the shape of a pillar with a diameter of 200nm and a length of 5mum. Elemental maps were obtained from the pillar specimen using a 200-kV cold-field emission gun (FEG) STEM model HD-2300C equipped with the EDAX genesis X-ray energy-dispersive spectrometry (XEDS) system through a spectrum imaging technique. In this study, elemental distributions of minor elements with weak signals were enhanced by applying principal component analysis (PCA), which is a superior technique to extract weak signals from a large dataset. The distributions of elements, especially the metallization component Ti and minor dopant As in this particular device, were successfully extracted by PCA. Finally, the 3D elemental distributions around the contact plug could be visualized by reconstruction from the tilt series of maps. 相似文献
47.
In order to facilitate the implementations ofTMN interface protocols/services studied inITU-T, it is very important to define profiles for supportingTMN management service. This paper proposes a concrete method for achieving this based on osi management standards as a promisingTMN implementation method. It proposes an idea of structuring theTMN ISP’S based on the structure of the osi managementISP’S. The paper discusses aTMN based on the osi managementISP’S. Finally the implementation as software is discussed and a software architecture for efficient application development is proposed. 相似文献
48.
49.
Watabe H Hatazawa J Ishiwata K Ido T Itoh M Iwata R Takahashi T Hatano K Nakamura T 《IEEE transactions on medical imaging》1995,14(4):688-696
We proposed a new method (;linearized method') to analyze neuroleptic ligand-receptor specific binding in a human brain using positron emission tomography (PET). We derived the linear equation to solve four rate constants, k(3), k(4), k(5), k(6) from PET data. This method does not demand a radioactivity curve in plasma as an input function to the brain, and can perform fast calculations in order to determine rate constants. We also tested the nonlinearized method including nonlinear equations which is a conventional analysis using plasma radioactivity corrected for ligand metabolites as an input function. We applied these methods to evaluate dopamine D(2) receptor specific binding of [(11)C] YM-09151-2. The value of B(max)/K(d)=k(3)/k (4) obtained by the linearized method was 5.72+/-3.1 which was consistent with the value of 5.78+/-3.4 obtained by the nonlinearized method. 相似文献
50.
Results from a number of studies have shown that individuals with profound developmental disabilities often show differential approach behavior to stimuli presented in a variety of formats, and that such behavior is a reasonably good predictor of reinforcement effects when these "preferred" stimuli are used subsequently in a contingent arrangement. Recent data suggest that reinforcement effects may be enhanced further by allowing individuals to select, just prior to training sessions, which (of several) preferred stimuli would be used as reinforcers, but whether this method is superior to one based on selection by a teacher or therapist has not been adequately addressed. We compared the effects of these two methods of reinforcer selection on rates of responding on a free-operant task, using stimuli previously identified as potential reinforcers. Results obtained with 4 subjects indicated little or no difference in reinforcement effects when stimuli were selected by subjects rather than experimenters. Implications of these results with respect to choice and its relation to reinforcement are discussed. 相似文献