全文获取类型
收费全文 | 1016篇 |
免费 | 35篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 238篇 |
金属工艺 | 14篇 |
机械仪表 | 18篇 |
建筑科学 | 33篇 |
矿业工程 | 2篇 |
能源动力 | 23篇 |
轻工业 | 73篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 131篇 |
一般工业技术 | 227篇 |
冶金工业 | 135篇 |
原子能技术 | 4篇 |
自动化技术 | 137篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 20篇 |
2017年 | 25篇 |
2016年 | 26篇 |
2015年 | 22篇 |
2014年 | 34篇 |
2013年 | 57篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 38篇 |
2009年 | 44篇 |
2008年 | 47篇 |
2007年 | 44篇 |
2006年 | 50篇 |
2005年 | 37篇 |
2004年 | 25篇 |
2003年 | 31篇 |
2002年 | 43篇 |
2001年 | 28篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 49篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 23篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有1060条查询结果,搜索用时 15 毫秒
1.
2.
3.
In addition to satisfying several competing objectives, many real-world applications are also characterized by a certain degree of noise, manifesting itself in the form of signal distortion or uncertain information. In this paper, extensive studies are carried out to examine the impact of noisy environments in evolutionary multiobjective optimization. Three noise-handling features are then proposed based upon the analysis of empirical results, including an experiential learning directed perturbation operator that adapts the magnitude and direction of variation according to past experiences for fast convergence, a gene adaptation selection strategy that helps the evolutionary search in escaping from local optima or premature convergence, and a possibilistic archiving model based on the concept of possibility and necessity measures to deal with problem of uncertainties. In addition, the performances of various multiobjective evolutionary algorithms in noisy environments, as well as the robustness and effectiveness of the proposed features are examined based upon five benchmark problems characterized by different difficulties in local optimality, nonuniformity, discontinuity, and nonconvexity 相似文献
4.
5.
The excavation of soil for the construction of basements or cut-and-cover tunnels results in ground movements. One particular concern is that the excavation-induced lateral soil movements may adversely affect any nearby pile foundation. The lateral loads imposed by the soil movements induce bending moments and deflections in the pile, which may lead to structural distress and failure. This paper presents the results of an actual full-scale instrumented study that was carried to examine the behavior of an existing pile due to nearby excavation activities resulting from the construction of a 16 m deep cut-and-cover tunnel. The pile was located 3 m behind a 0.8 m thick diaphragm wall. Excavation to the formation level that was 16 m below the ground surface resulted in a maximum lateral pile movement of 28 mm. A simplified numerical procedure based on the finite-element method was used to analyze the pile response. Generally, the theoretical predictions were in reasonable agreement with the measured results. 相似文献
6.
7.
We report a dispersion slope equalizer on a planar lightwave circuit for wavelength division multiplexing (WDM) transmission. This device consists of an array of lattice-formed equalizers with different compensation values fabricated on one wafer and arrayed-waveguide gratings for wavelength multi/demultiplexing. We describe its configuration, operational principle, parameter design, fabrication, and measured characteristics in detail. N/spl times/20 and N/spl times/40 Gb/s slope equalizers were fabricated and their characteristics agreed well with designed values. We also report a reduction in the bias electrical power needed for thermooptic phase shifters in the equalizer array that we realized by employing a phase trimming technique normally used for optical switches. 相似文献
8.
Scaffold‐guided tissue engineering based on synthetic and natural occurring polymers has gained many interests in recent year. In this study, the development of a chitosan‐heparin artificial extracellular matrix (AECM) is reported. Three‐dimensional, macroporous composite AECMs composed of heparin (Hep) and chitosan (Chito) were prepared by an interpolyelectrolyte complex/lyophilization method. The Chito‐Hep composite AECMs were, respectively, crosslinked with glutaraldehyde, as well as cocrosslinked with N,N‐(3‐dimethylaminopropyl)‐N′‐ethyl carbodiimide (EDC/NHS) and N‐hydroxysuccinimide (NHS). The crosslinking reactions were examined by FT‐IR analysis. In physiological buffer solution (PBS), the EDC/NHS‐crosslinked Chito‐Hep composite AECM showed a relative lower water retention ratio than its glutaraldehyde‐crosslinked counterparts. The EDC/NHS‐crosslinked Chito‐Hep composite AECMs showed excellent biocompatibility, according to the results of the in vitro cytotoxic test. This result suggested that the EDC/NHS‐crosslinked Chito‐Hep composite AECMs might be a potential biomaterial for scaffold‐guided tissue engineering applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
9.
Cntextual logic provides a mechanism to reason about modules.In this paper,this theory of modules if modules is extended to a context theory of classes where class is in the true spirit of object-oriented databases.The logic,referred to as CLOG,is class-based.CLOG supports class,object identity,multiple role of object, monotonic and non-monotonic inheritance of data and method,method factoring,views,derived and query classes.Views and derived classes are queries in themselves.Objects are pure data terms representing the ground instances of facts in the class.Object identity is a first class term in the logic.Inheritance is handled through delegation. 相似文献
10.
Masahiro Baba Goh Itoh Haruhiko Okumura 《Journal of the Society for Information Display》2007,15(3):205-211
Abstract— In this paper, a software‐processed edge‐ and level‐adaptive overdrive (SELAO) method, which is a novel overdrive technique that utilizes not only a temporal change of gray levels but also a spatial edge intensity of motion pictures, is proposed. The SELAO method is a software video‐processing technology to improve motion‐picture quality rendered on LCDs more than is possible with a conventional SLAO method without edge‐adaptive overdrive, and it works in real time on commonly used personal computers (PCs). 相似文献