全文获取类型
收费全文 | 777篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 11篇 |
综合类 | 6篇 |
化学工业 | 174篇 |
金属工艺 | 15篇 |
机械仪表 | 8篇 |
建筑科学 | 76篇 |
矿业工程 | 6篇 |
能源动力 | 35篇 |
轻工业 | 69篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 59篇 |
一般工业技术 | 122篇 |
冶金工业 | 81篇 |
原子能技术 | 3篇 |
自动化技术 | 128篇 |
出版年
2023年 | 3篇 |
2022年 | 17篇 |
2021年 | 17篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 15篇 |
2016年 | 22篇 |
2015年 | 22篇 |
2014年 | 18篇 |
2013年 | 44篇 |
2012年 | 34篇 |
2011年 | 52篇 |
2010年 | 26篇 |
2009年 | 29篇 |
2008年 | 41篇 |
2007年 | 34篇 |
2006年 | 36篇 |
2005年 | 33篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 15篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有804条查询结果,搜索用时 15 毫秒
41.
Björn Stille Gunnar Gustafson 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2010,25(4):346-356
The 6 km tunnel under the Namntall hill is a part of the Botniabanan railway project in northern Sweden. The tunnels were excavated by means of drilling and blasting and with, for Scandinavian conditions, a normal grouting routine. The grouting is performed to reduce water ingress into the tunnel to the level defined in the contract. When the water ingress requirements proved difficult to meet, it was obvious that the geological and the hydrogeological conditions in the tunnel would dictate the work processes. A distinctive change in rock conditions influenced both grouting performance and seepage into the tunnel. The rock conditions and the grouting were quantified throughout the project and these are summarized in this paper. It can be concluded that the strongest correlation is between the water ingress, the hydrogeological conditions and the density of the zones and the conditions in and around these zones. The paper suggests a different approach to hydrogeological prognosis and the grouting process, such as distribution of grouting classes, increased mixer capacities and regular use of two grouting rounds. 相似文献
42.
Pustovit VN Sotelo JA Niklasson GA 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(3):513-518
We propose a new formalism for computing the optical properties of small clusters of particles. It is a generalization of the coupled dipole-dipole particle-interaction model and allows one in principle to take into account all multipolar interactions in the long-wavelength limit. The method is illustrated by computations of the optical properties of N = 6 particle clusters for different multipolar approximations. We examine the effect of separation between particles and compare the optical spectra with the discrete-dipole approximation and the generalized Mie theory. 相似文献
43.
The pressure towards tighter or “seamless” integration of health information systems is a recurring issue with both practical
and analytical relevance. It taps into a discourse in the IS literature in general and organisation and management science
in particular. Unfortunately, the prevailing perception of integration in the IS literature is as a predominantly technical
issue. The CSCW literature, however, is attentive to the socio-technical aspects of integration. Building on this – but supplemented
with recent elaborations in science studies – we aim at exploring the unintended consequences of information systems integration.
A user-led perspective implies emphasising the tailoring to local needs based on in-depth studies of the micro practices.
We argue, however, that the condition for such an approach is radically undermined by politically motivated, regional changes
towards integration with implicated standardisation. Enforcing order in the form of standards across multiple local settings,
seemingly a prerequisite for tight integration, simultaneously produces disorder or additional work in other locations for
other users. Empirically, our study is based on a large, ongoing integration effort at the University hospital of Northern
Norway, specifically studying work practices and perceptions across multiple laboratories. 相似文献
44.
Gunnar Gudnason Erik Bruun Morten Haugland 《Analog Integrated Circuits and Signal Processing》2000,22(1):81-89
This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation (FES). The purpose of FES is to restore muscular control in disabled patients. The chip performs all the signal processing required in an implanted neural stimulator. The power and digital data transmission to the stimulator passes through a 5 MHz inductive link. From the signals transmitted to the stimulator, the chip is able to generate charge-balanced current pulses with a controllable length up to 256 s and an amplitude up to 2 mA, for stimulation of nerve fibers. The quiescent current consumption of the chip is approx. 650 A at supply voltages of 6–12 V, and its size is 3.9×3.5 mm2. It has 4 output channels for use in a multipolar cuff electrode. 相似文献
45.
46.
47.
48.
49.
Kuczewski B Marquardt CM Seibert A Geckeis H Kratz JV Trautmann N 《Analytical chemistry》2003,75(24):6769-6774
Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values. 相似文献
50.
Wang JS Taylor M Flivik G Lidgren L 《Journal of materials science. Materials in medicine》2003,14(1):55-61
Debonding of the stem–cement interface has been implicated in the initiation of failure of cemented femoral stems. The objective of this work was to examine some of the parameters which influence the interface static shear strength, including surface finish, cement type, pre-treatments and porosity. Surface finish was found to have the greatest effect on the interface strength. Increasing the surface roughness by a factor of 100 increases the interface shear strength by a factor of 20. However, increasing the surface roughness above a certain value was found to have no additional affect. This was due to failure in the cement itself rather than at the cement–stem interface. There were significant differences between some of the different cement types regarding the interface strength. Pre-heating the stem produced a six fold reduction in cement porosity at the stem–cement interface, however, resulting in only a minor influence on the static interface strength. Generally, no significant correlation was found between the cement porosity and the static interfacial shear strength. 相似文献