全文获取类型
收费全文 | 1162篇 |
免费 | 49篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 52篇 |
化学工业 | 323篇 |
金属工艺 | 27篇 |
机械仪表 | 25篇 |
建筑科学 | 15篇 |
能源动力 | 76篇 |
轻工业 | 109篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 57篇 |
一般工业技术 | 248篇 |
冶金工业 | 117篇 |
原子能技术 | 51篇 |
自动化技术 | 107篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 26篇 |
2021年 | 42篇 |
2020年 | 20篇 |
2019年 | 27篇 |
2018年 | 32篇 |
2017年 | 32篇 |
2016年 | 49篇 |
2015年 | 26篇 |
2014年 | 56篇 |
2013年 | 88篇 |
2012年 | 82篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 66篇 |
2008年 | 60篇 |
2007年 | 56篇 |
2006年 | 48篇 |
2005年 | 30篇 |
2004年 | 30篇 |
2003年 | 32篇 |
2002年 | 20篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 39篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1215条查询结果,搜索用时 343 毫秒
11.
Yoshinori Kanno 《Journal of Materials Science》1990,25(4):1987-1990
ZrO2-SiO2 (11) mixtures and ZrO2 particles were prepared by a sol-gel method from the solutions of ZrOCl2·8H2O (ZOC) + Si(OC2H5)4 (TEOS) + C2H5OH and ZOC + C2H5OH + H2O + NH4Cl systems, respectively. Quantitative changes of phase crystallized by heating were compared with those of ZOC + TEOS + H2O and/or ZrO(NO3)2 · 2H2O + H2O systems, respectively. The stability of metastable tetragonal (mt)-ZrO2 particles depends on the Young's modulus of the SiO2 matrix. Transition metal oxides existing on the interface assisted in stabilizing mt-ZrO2. The order of the assistance agreed with that of the relative field strengths of their oxides. A relationship between the ionic radius and the volatility of anionic groups, and the difficulty of nucleation for the martensitic transformation accompanying a shear stress, is suggested. 相似文献
12.
Yusuke Soraji Kazuo Furuta Taro Kanno Hisae Aoyama Satoru Inoue Daisuke Karikawa Makoto Takahashi 《Cognition, Technology & Work》2012,14(2):93-105
Since controller teams are in charge of en-route air traffic control, team cooperation is a key issue for good control performance. We conducted ethnographic field observation at the Tokyo Area Control Center and then analyzed the obtained data to develop a cognitive model of team cooperation in en-route air traffic control. We segmented conversational records, behavioral records, and so on by control unit, and then clarified relations between the segments and identified expert knowledge and judgment behind them. Cognitive processes of controller teams were reconstructed based on a concept of distributed cognition. The analysis revealed that the mutual belief model is applicable to team cooperation processes, the role assignment of tasks within a controller team is implicit and that control plans are implemented smoothly once team situation awareness has been established. A cognitive model of controllers?? team cooperation has been constructed based on these findings. 相似文献
13.
Guyu Zhang Christian A. Duncan Jinko Kanno Rastko R. Selmic 《Journal of Intelligent and Robotic Systems》2014,74(3-4):869-891
We present a set of algorithms for the navigation of Unmanned Ground Vehicles (UGVs) towards a set of pre-identified target nodes in coordinate-free and localization-free wireless sensor and actuator networks. The UGVs are equipped with a set of wireless listeners that provide sensing information about the potential field generated by the network of actuators. Two main navigation scenarios are considered: single-UGV, single-destination navigation and multi-UGV, multi-destination navigation. For the single-UGV, single-destination case, we present both centralized and distributed navigation algorithms. Both algorithms share a similar two-phase concept. In the first phase, the system assigns level numbers to individual nodes based on their hop distance from the target nodes. In the second phase, the UGV uses the potential field created by the network of actuators to move towards the target nodes, requiring cooperation between triplets of actuator nodes and the UGV. The hop distance to the target nodes is used to control the main moving direction while the potential field, which can be measured by listeners on the UGV, is used to determine the UGV’s movement. For the multi-UGV, multi-destination case, we present a decentralized allocation algorithm such that multiple UGVs avoid converging to the same destination. After each UGV determines its destination, the proposed navigation scheme is applied. The presented algorithms do not attempt to localize UGVs or sensor nodes and are therefore suitable for operating in GPS-free/denied environments. We also present a study of the communication complexity of the algorithms as well as simulation examples that verify the proposed algorithms and compare their performances. 相似文献
14.
Attempts were carried out to enhance the surface hydrophilicity of poly(L ‐lactide), that is, poly(L ‐lactic acid) (PLLA) film, utilizing enzymatic, alkaline, and autocatalytic hydrolyses in a proteinase K/Tris–HCL buffered solution system (37°C), in a 0.01N NaOH solution (37°C), and in a phosphate‐buffered solution (100°C), respectively. Moreover, its chain‐scission mechanisms in these different media were studied. The advancing contact‐angle (θa) value of the amorphous‐made PLLA film decreased monotonically with the hydrolysis time from 100° to 75° and 80° without a significant molecular weight decrease, when enzymatic and alkaline hydrolyses were continued for 60 min and 8 h, respectively. In contrast, a negligible change in the θa value was observed for the PLLA films even after the autocatalytic hydrolysis was continured for 16 h, when their bulk Mn decreased from 1.2 × 105 to 2.2 × 104 g mol?1 or the number of hydrophilic terminal groups per unit weight increased from 1.7 × 10?5 to 9.1 × 10?5 mol g?1. These findings, together with the result of gravimetry, revealed that the enzymatic and alkaline hydrolyses are powerful enough to enhance the practical surface hydrophilicity of the PLLA films because of their surface‐erosion mechanisms and that its practical surface hydrophilicity is controllable by varying the hydrolysis time. Moreover, autocatalytic hydrolysis is inappropriate to enhance the surface hydrophilicity, because of its bulk‐erosion mechanism. Alkaline hydrolysis is the best to enhance the hydrophilicity of the PLLA films without hydrolysis of the film cores, while the enzymatic hydrolysis is appropriate and inappropriate to enhance the surface hydrophilicity of bulky and thin PLLA materials, respectively, because a significant weight loss occurs before saturation of θa value. The changes in the weight loss and θa values during hydrolysis showed that exo chain scission as well as endo chain scission occurs in the presence of proteinase K, while in the alkaline and phosphate‐buffered solutions, hydrolysis proceeds via endo chain scission. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1628–1633, 2003 相似文献
15.
Tadaharu Adachi Wakako Araki Takuya Nakahara Akihiko Yamaji Masahiro Gamou 《应用聚合物科学杂志》2002,86(9):2261-2265
The relationship between the postcuring conditions and fracture toughness on three silica particulate‐filled epoxy composites was investigated. The glass transition temperature, Tg, and the fragility parameter, m, derived from the thermo‐viscoelasticity, were used to characterize the composites, which were postcured under various conditions. The glass transition temperature and fragility both depended on both of the curing conditions and the volume fraction of silica particles. The glass transition temperature increased with the postcuring time and temperature, while the fragility generally decreased as the volume fraction increased. There was no direct correlation between the glass transition temperature and fragility. The fracture toughness depended on both the glass transition temperature and fragility. The composites with a high glass transition temperature and low fragility had high fracture toughness. These results indicate that the glass transition temperature and fragility are useful parameters for estimating the fracture toughness of the silica particulate‐filled epoxy composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2261–2265, 2002 相似文献
16.
Takuya Goto 《Electrochimica acta》2005,50(6):1283-1288
Electrochemical formation of aluminum nitride was investigated in molten LiCl-KCl-Li3N systems at 723 K. When Al was anodically polarized at 1.0 V (versus Li+/Li), oxidation of nitride ions proceeded to form adsorbed nitrogen atoms, which reacted with the surface to form AlN film. The obtained nitrided film had a thickness of sub-micron order. The obtained nitrided layer consisted of two regions; the outer layer involving AlN and aluminum oxynitride and the inner layer involving metallic Al and AlN. When Al electrode was anodically polarized at 2.0 V, anodic dissolution of Al electrode occurred to give aluminum ions, which reacted with nitride ions in the melt to produce AlN particles (1-5 μm of diameter) of wurtzite structure. 相似文献
17.
ABSTRACT Preparation of poly(thiophene-alt-pyrrole bearing mesogen) was carried out with Migita–Kosugi–Stille coupling type polycondensation with an aid of Pd(0) complex catalyst. The resultant polymer shows lyotropic liquid crystallinity with good film-forming property. The smectic fan-shaped texture is maintained after completion of evaporation of solvent from the polymer solution. The cast film having liquid crystal (LC) order shows light emission function upon irradiation of excitation light at 460 nm. The polymer shows LC domain emission. Mechanical orientation allows to yield LC domain aligned film with band structure. Chiral mesogenic side chain induces π-conjugated main chain helicity from distance in molecular level. 相似文献
18.
Glass transition temperatures Tg and Raman spectra of KPO3·Ln(PO3)3 (Ln=rare earth ion) glasses were measured for all rare earth members (except Pm). From the series behavior of the Tg and Raman data, it is concluded that the coordination number around rare earth ions changes, probably from nine to eight, in the middle of the rare earth series. 相似文献
19.
Two‐way multi‐view 2‐D/3‐D display combining LC lens and HVxDP panel using novel pixel arrangement
下载免费PDF全文
![点击此处可从《Journal of the Society for Information Display》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jin Matsushima Yukie Ibata Kazunori Masumura Takuya Asai Tetsushi Sato Koji Shigemura 《Journal of the Society for Information Display》2016,24(4):252-261
We have developed a two‐way multi‐view 2‐D/3‐D display combining a liquid crystal lens and horizontally and vertically x times‐density pixels (HVxDP) arrangement. The two‐way multi‐view display features the same display resolution in 2‐D and 3‐D modes and a quite small color moiré for landscape and portrait, respectively, when using the HVxDP arrangement. In this paper, we realized suitable 3‐D properties for achieving a good balance between 3‐D moiré and 3‐D crosstalk for landscape and portrait by a two‐way liquid crystal lens with two kinds of focal lengths for the edge part and the center part of the lens. 相似文献
20.
This paper deals with the frame topology optimization under the frequency constraint and proposes an algorithm that solves a sequence of relaxation problems to obtain a local optimal solution with high quality. It is known that an optimal solution of this problem often has multiple eigenvalues and the feasible set is disconnected. Due to these two difficulties, conventional nonlinear programming approaches often converge to a local optimal solution that is unacceptable from a practical point of view. In this paper, we formulate the frequency constraint as a positive semidefinite constraint of a certain symmetric matrix, and then relax this constraint to make the feasible set connected. The proposed algorithm solves a sequence of the relaxation problems with gradually decreasing the relaxation parameter. The positive semidefinite constraint is treated with the logarithmic barrier function and, hence, the algorithm finds no difficulty in multiple eigenvalues of a solution. Numerical experiments show that global optimal solutions, or at least local optimal solutions with high qualities, can be obtained with the proposed algorithm. 相似文献