全文获取类型
收费全文 | 1246篇 |
免费 | 34篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 144篇 |
金属工艺 | 6篇 |
机械仪表 | 6篇 |
建筑科学 | 13篇 |
矿业工程 | 3篇 |
能源动力 | 19篇 |
轻工业 | 44篇 |
水利工程 | 5篇 |
无线电 | 26篇 |
一般工业技术 | 158篇 |
冶金工业 | 747篇 |
原子能技术 | 8篇 |
自动化技术 | 86篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 12篇 |
2018年 | 21篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 16篇 |
2014年 | 25篇 |
2013年 | 49篇 |
2012年 | 32篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 23篇 |
2008年 | 23篇 |
2007年 | 21篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 15篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 34篇 |
1998年 | 238篇 |
1997年 | 144篇 |
1996年 | 99篇 |
1995年 | 33篇 |
1994年 | 53篇 |
1993年 | 35篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 7篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 20篇 |
1979年 | 4篇 |
1977年 | 18篇 |
1976年 | 41篇 |
1975年 | 2篇 |
1970年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1284条查询结果,搜索用时 93 毫秒
71.
72.
H Tsukamoto T Kurokawa K Hirata S Ishibashi HK Mishima 《Canadian Metallurgical Quarterly》1998,46(5):987-991
We investigated the effect of two isomers of retinoic acid (RA), all-trans RA and 9-cis RA, on the proliferation of Y79 human retinoblastoma cells. The two isomers inhibited the cell proliferation in a concentration-dependent manner. The IC50 for this inhibition by all-trans RA and 9-cis RA was 1.50 and 0.15 microM, respectively. The inhibitory effect of 9-cis RA on Y79 cell growth was observed within 24 hr, thereafter the cell number was gradually decreased. In contrast, no inhibition by all-trans RA of Y79 cell growth was observed within 24 hr, thereafter the cell number was slightly increased. In these cases, the cell viability at 4 days after the addition of 9-cis RA and all-trans RA was more than 90% and 95%, respectively. These results indicate that the two RA inhibit the proliferation of Y79 human retinoblastoma cells without inducing the cell death and that the effect of 9-cis RA on the inhibition of Y79 cell growth is much greater than that of all-trans RA. 相似文献
73.
74.
75.
A heteroassociative joint transform correlation (JTC) technique is proposed for recognizing and tracking multiple heteroassociative or dissimilar targets from gray-level image sequences by use of the concept of fringe-adjusted JTC and a multiple-target-detection algorithm. A fringe-adjusted JTC technique is used to ensure quantification of the similarities among several input images while it satisfies the equal-correlation-peak criterion. Tracking is accomplished by retrieval of the target motion information estimated from multiple consecutive image frames. An enhanced version of the fringe-adjusted filter is incorporated into the heteroassociative multiple-target-detection process to optimize the correlation performance. The feasibility of the proposed technique is tested by computer simulation with real infrared image data. 相似文献
76.
Bal K. Puri Mamta Gautam 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1980,30(1):244-248
Optimum conditions have been developed for the extraction of cobalt thioxanthate by solid-liquid separation after liquid-liquid extraction. 相似文献
77.
Bal G Ren K 《Journal of the Optical Society of America. A, Optics, image science, and vision》2003,20(12):2355-2364
We introduce a generalized diffusion equation that models the propagation of photons in highly scattering domains with thin nonscattering clear layers. Classical diffusion models break down in the presence of clear layers. The model that we propose accurately accounts for the clear-layer effects and has a computational cost comparable to that of classical diffusion. It is based on modeling the propagation in the clear layer as a local tangential diffusion process. It can be justified mathematically in the limit of small mean free paths and is shown numerically to be very accurate in two- and three-dimensional idealized cases. We believe that this model can be used as an accurate forward model in optical tomography. 相似文献
78.
The paper proposes a hierarchical control design of an electro-hydraulic actuator, which is used to improve the roll stability of vehicles. The purpose of the control system is to generate a reference torque, which is required by the vehicle dynamic control. The control-oriented model of the actuator is formulated in two subsystems. The high-level hydromotor is described in a linear form, while the low-level spool valve is a polynomial system. These subsystems require different control strategies. At the high level, a linear parameter-varying control is used to guarantee performance specifications. At the low level, a control Lyapunov-function-based algorithm, which creates discrete control input values of the valve, is proposed. The interaction between the two subsystems is guaranteed by the spool displacement, which is control input at the high level and must be tracked at the low-level control. The spool displacement has physical constraints, which must also be incorporated into the control design. The robust design of the high-level control incorporates the imprecision of the low-level control as an uncertainty of the system. 相似文献
79.
80.
We describe a computer system called LearnIT II, which can observe an iterative solution to a parametric design problem and learn the design strategy employed. The program uses identification tree learning to determine which attributes of the design best indicate which design modifications the designer will make. The program re-represents the identification trees as design rules which it can then use to create new designs automatically. Because the rules are learned from the designer, the new designs reflect the designer's engineering judgment, knowledge of implicit constraints, and overall familiarity with the problem. The program has a number of intended uses. As a design automation tool, it provides a convenient means for exploring a design space. As a design documentation tool, it implicitly captures the original designer's insights about a problem and brings them to bear when it is necessary to modify the design. As a tool for preserving institutional memory, it captures design strategies and preserves them for future use. 相似文献