全文获取类型
收费全文 | 2514篇 |
免费 | 88篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 161篇 |
综合类 | 4篇 |
化学工业 | 933篇 |
金属工艺 | 73篇 |
机械仪表 | 57篇 |
建筑科学 | 75篇 |
矿业工程 | 2篇 |
能源动力 | 93篇 |
轻工业 | 287篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 142篇 |
一般工业技术 | 453篇 |
冶金工业 | 55篇 |
原子能技术 | 63篇 |
自动化技术 | 200篇 |
出版年
2023年 | 8篇 |
2022年 | 24篇 |
2021年 | 55篇 |
2020年 | 33篇 |
2019年 | 35篇 |
2018年 | 48篇 |
2017年 | 43篇 |
2016年 | 62篇 |
2015年 | 39篇 |
2014年 | 84篇 |
2013年 | 156篇 |
2012年 | 120篇 |
2011年 | 175篇 |
2010年 | 100篇 |
2009年 | 144篇 |
2008年 | 144篇 |
2007年 | 133篇 |
2006年 | 100篇 |
2005年 | 114篇 |
2004年 | 99篇 |
2003年 | 90篇 |
2002年 | 89篇 |
2001年 | 62篇 |
2000年 | 48篇 |
1999年 | 43篇 |
1998年 | 31篇 |
1997年 | 41篇 |
1996年 | 39篇 |
1995年 | 29篇 |
1994年 | 40篇 |
1993年 | 29篇 |
1992年 | 28篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 21篇 |
1988年 | 15篇 |
1987年 | 20篇 |
1986年 | 29篇 |
1985年 | 26篇 |
1984年 | 25篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1974年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有2608条查询结果,搜索用时 17 毫秒
71.
Takeshi Masuda 《Computer Vision and Image Understanding》2009,113(11):1158-1169
We propose a method for coarse registration of multiple range images that uses a log-polar height map (LPHM) as the key for establishing correspondence. The LPHM is a local height map orthogonally mapped on the tangent plane with the log-polar coordinate system. The input range images are roughly represented by signed distance field (SDF) samples. For each SDF sample, an LPHM is generated and is converted to an invariant feature vector. Point correspondence is established by a nearest neighbor search in feature space. The RANSAC algorithm is applied on the corresponding point pairs between each pair of range images, and the pairwise registration of input range images is determined by the extracted inlier point pairs. Finally, the global registration is determined by constructing a view tree, which is the spanning tree that maximizes the total number of inlier point pairs. The result of coarse registration is used as the initial state of the fine registration and modeling. The proposed method was tested on multiple real range image datasets. 相似文献
72.
Azwirman Gusrialdi Sandra Hirche David Asikin Takeshi Hatanaka Masayuki Fujita 《Intelligent Service Robotics》2009,2(4):195-204
In this paper, we investigate coverage control problem for mobile sensor networks. The novelty is to consider an anisotropic sensor model whose performance depends not only on the distance but also on the orientation to a target point. By adapting Lloyd algorithm, a distributed control law is derived. Aside from coverage, we also show that the control law guarantees collision avoidance between the agents. The performance of the control laws is demonstrated through not only numerical simulation but also experiments on a mobile robot test bed. 相似文献
73.
This paper aims to assess quantitatively the actual visual environment of uncontrolled urban downtown intersections in Japan in relation to frequently occurring crossing collisions and to discuss the safety countermeasures for them. In Field Study 1 dealing with direct visibility, our ultra-wide-angle photograph analysis revealed that most of the right/left-ward visible range at 11 intersections were insufficient to check safety, and the quality of direct visibility was closely associated with causing crossing collisions. The countermeasures to reduce a blind area were determined to be a top priority. In Field Study 2 dealing with indirect visibility, more than half of the 25 traffic convex mirrors had marked shortcomings for preventive safety, and ergonomics guidelines ensuring indirect visibility were proposed for installing traffic convex mirrors. Low-cost/low-technology-oriented countermeasures are highly recommended to obtain clear/sufficient images of crucial information satisfying drivers' requirements on traffic convex mirrors in accordance with those ergonomics guidelines was highly recommended. Crossing collisions could be prevented by improvement of poor direct and indirect visibility. 相似文献
74.
Uniformly layered mixture of the succeeding members in the structure series was found in artificially layered Bi2Sr2Ca
n–1Cu
n
O2n+4 films synthesized by a three-target sequential sputter deposition technique. The intergrowth structure was quantitatively evaluated by X-ray analysis technique. An averagedc-axis (half) unit length and a plane spacing d0-0.31 nm
in the intergrowth structure are considered as a modulation wavelength and an average lattice of superlattice in the analysis. It is shown that the X-ray diffraction patterns observed in our films are in good agreement with that predicted by the superlattice model. 相似文献
75.
Correlation between Chemical Dopants and Topological Defects in Catalytically Active Nanoporous Graphene 下载免费PDF全文
76.
Factors associated with serum magnesium and vascular stiffness in maintenance hemodialysis patients 下载免费PDF全文
Mai Yorifuji Takahiro Kuragano Sayuri Kawada Wataru Fukao Kazuhiro Toyoda Takeshi Nakanishi 《Hemodialysis international. International Symposium on Home Hemodialysis》2018,22(3):342-350
Introduction : We evaluated the associated factors of serum magnesium in patients on maintenance hemodialysis (MHD). Furthermore, we evaluated the relationship between low serum magnesium and arteriosclerosis in these patients. Methods : In 129 patients on MHD, we evaluated the blood levels of magnesium, brachial‐ankle pulse wave velocity (ba‐PWV), ankle‐brachial index (ABI), and intima‐media thickness of the common carotid artery (IMT). Findings : In MHD patients, the serum level of magnesium was significantly correlated with age, calcium, TNF‐α, albumin, and ba‐PWV but not with ABI or IMT. In the multiple regression analysis, albumin (P = 0.0001, β = 0.31) and calcium (P = 0.029, β = 0.18) were selected as significant predictors of the magnesium level in MHD patients. Furthermore, the serum level of magnesium, as well as systolic blood pressure (P = 0.0001, β = 0.32) and age (P = 0.005, β = 0.25), were selected as significant (P = 0.012, β = ?0.22) predictors of ba‐PWV in MHD patients. Discussion : In MHD patients, the serum magnesium level was associated with the serum levels of calcium and albumin. Furthermore, a low serum magnesium level in MHD patients was associated with the index of vascular stiffness. 相似文献
77.
78.
Takeshi Emura 《Computational statistics & data analysis》2010,54(12):3033-3043
A goodness-of-fit testing procedure for Archimedean copula (AC) models is developed based on right-censored data. The proposed approach extends an existing method, which is suitable for the Clayton model, to general AC models. Asymptotic properties of the proposed test statistics under the true model assumption are derived. Simulation analysis shows that the proposed test has reasonable performance. Finally, two real data examples are analyzed for illustrative purposes. 相似文献
79.
Automatic optical flank wear measurement of microdrills using level set for cutting plane segmentation 总被引:1,自引:0,他引:1
We address the problem of automatic optical flank wear measurement for microdrill bits’ inspection. Cutting plane segmentation
of microdrill bits is a fundamental step in the measurement. However, in the case of smeared microdrill bits, cutting planes
cannot be segmented correctly by conventional methods. To exactly extract the cutting plane, a level set technique is proposed
to segment it from a drill bit image; then we adopt a projection profile-based method for measuring the features of flank
wear of microdrills. A new feature of flank wear, called “end wear length”, is also introduced for flank wear evaluation with three other existing features. Experimental results indicate that it
is a robust and effective approach for automatic flank wear measurement of microdrills in printed circuit board (PCB) manufacturing. 相似文献
80.
Yoshitaka Sawa Kenji Yamashita Takeshi Kitadani Daiji Noda Tadashi Hattori 《Microsystem Technologies》2010,16(8-9):1369-1375
The nickel electroforming method using a high-concentration nickel sulfamate bath is commonly used to fabricate micro metal molds in the LIGA process; however, this method does not produce micro metal molds of sufficient hardness. One means of improving the hardness of micro metal molds made using the nickel electroforming method is to include additives in the nickel plating solution. Another method is nickel alloy plating or a similar technique. In this research, we used a nickel–boron (Ni–B) electroless alloy plating method to obtain a hard nickel plated film having hardness of 832 Hv. It was also ascertained that Ni–B electroless alloy plated film retains its high hardness even during heat treatment in conditions of 250°C for 1 h. To deal with the high stresses developed in high-hardness plated films, we proposed double-layer nickel electroforming. This method is covered and used on conventional nickel electroforming layer by high hardness micro mold. High hardness micro metal mold using double-layer was fabricated by nickel electroforming and Ni–B electroless alloy plating method. 相似文献