全文获取类型
收费全文 | 462篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 77篇 |
金属工艺 | 1篇 |
机械仪表 | 16篇 |
建筑科学 | 11篇 |
能源动力 | 42篇 |
轻工业 | 21篇 |
水利工程 | 1篇 |
无线电 | 65篇 |
一般工业技术 | 72篇 |
冶金工业 | 66篇 |
原子能技术 | 13篇 |
自动化技术 | 96篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 10篇 |
2014年 | 8篇 |
2013年 | 27篇 |
2012年 | 29篇 |
2011年 | 20篇 |
2010年 | 19篇 |
2009年 | 18篇 |
2008年 | 39篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有484条查询结果,搜索用时 0 毫秒
41.
对带有开关电路的2.4 GHz极化分集印刷天线进行电磁场及电磁场与电路协同仿真 通过采用极化分集技术,可以用低成本PCB基片制造具有良好接收机性能的无线局域网设备(WLAN)天线.本文将描述如何使用最新的三维电磁场(EM)仿真工具来设计和仿真一对2.4GHz正交极化的印刷偶极子天线,同时预测表面电流和相关的远场辐射图. 相似文献
42.
This study presents the potential of the burning and/or transmutation (B/T) of transuraniums (TRUs), discharged from the pressured water reactor PWR-UO2 spent fuel, in the modified PROMETHEUS-H fusion reactor. Two different design shapes (Models A and B) were considered. The transmutation zone (TZ), which contains the mixture of TRU nuclides (10%), was located in the modified blankets. The volume fraction of Pu in the mixture is raised from 0 to 40% stepped by 10% to determine its effect on the B/T. The fuel spheres were cladded with SiC (5%) and cooled with high-pressured helium gas (85%) for nuclear heat transfer. The calculations were performed for an operation period (OP) of up to 10 years by 75% plant factor (η) under a neutron wall load (P) of 4.7 MW/m2. The results bring out that: (1) the Model B transmutes the TRUs more rapidly than the Model A; (2) the effective half-lives decrease about 20 and 40% with the increase of Pu fraction in the cases of Models A and B, respectively; (3) the M values are quite high with respect to the M value of the original PROMETHEUS fusion reactor; (4) the blankets can produce substantial electricity in situ. 相似文献
43.
44.
Hiong Yap Gan Yee Cheong Lam Nam Trung Nguyen Kam Chiu Tam Chun Yang 《Microfluidics and nanofluidics》2007,3(1):101-108
In this paper, we examined mixing of various two-fluid flows in a silicon/glass microchannel based on the competition of dominant
forces in a flow field, namely viscous/elastic, viscous/viscous and viscous/inertial. Experiments were performed over a range
of Deborah and Reynolds numbers (0.36 < De < 278, 0.005 < Re < 24.2). Fluorescent dye and microshperes were used to characterize
the flow kinematics. Employing abrupt convergent/divergent channel geometry, we achieved efficient mixing of two-dissimilar
viscoelastic fluids at very low Reynolds number. Enhanced mixing was achieved through elastically induced flow instability
at negligible diffusion and inertial effects (i.e. enormous Peclet and Elasticity numbers). This viscoelastic mixing was achieved
over a short effective mixing length and relatively fast flow velocities. 相似文献
45.
Swee Yeow Yap McCanny J.V. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2004,51(7):384-389
With the advent of new video standards such as MPEG-4 part-10 and H.264/H.26L, demands for advanced video coding, particularly in the area of variable block size video motion estimation (VBSME), are increasing. In this paper, we propose a new one-dimensional (1-D) very large-scale integration architecture for full-search VBSME (FSVBSME). The VBS sum of absolute differences (SAD) computation is performed by re-using the results of smaller sub-block computations. These are distributed and combined by incorporating a shuffling mechanism within each processing element. Whereas a conventional 1-D architecture can process only one motion vector (MV), this new architecture can process up to 41 MV sub-blocks (within a macroblock) in the same number of clock cycles. 相似文献
46.
47.
SW Tan M Singh LC Ho J Howe KT Moe XQ Chen GC Ng EH Yap 《Canadian Metallurgical Quarterly》1997,27(8):947-954
Our previous studies have shown that monoclonal antibodies (MAbs) to Blastocystis hominis react mainly with carbohydrate epitopes, while 1 MAb (1D5) reacts specifically with a protein of 30.5 kDa. In the present study, 3 monoclonal antibodies (1D5, 1E7 and 4F7) were used in immunogold localization. 1E7 and 4F7 were found to react primarily with the surface coat, while 1D5 was plasma membrane-specific. In the presence of complement, only 1D5 exhibited a cytotoxic effect on B. hominis whereas 1E7 and 4F7 did not, suggesting that the surface coat of B. hominis could serve as an immunological barrier against host antibodies. Using a recently described agar plating method, only 1D5 exhibited significant (P < 0.01) complement-independent cytotoxicity to B. hominis, inhibiting colony growth at low concentrations. Parasites that had been exposed to 1D5 were morphologically smaller than those that were not exposed to this MAb. Colonies that grew in the presence of 1D5 were isolated and grown in liquid medium containing increasing amounts of the cytotoxic MAb. Two clones that grew well in liquid medium containing 1D5 were also able to develop into colonies in soft agar. This study has shown that the 30.5 kDa protein found on the plasma membrane of B. hominis is a functionally important protein and that not all cells within a certain population would be susceptible to the cytotoxic effects of 1D5. These findings suggest that a heterogenous population exists in continuously maintained cultures of B. hominis. 相似文献
48.
Research has shown that learned fear emerges in a response-specific sequence. For example, freezing is observed at a younger age than is potentiated startle (P. Hunt & B. A. Campbell, 1997). The present study shows that the age at which a specific learned fear response emerges is influenced by the animal's early experiences. Specifically, fear potentiation of startle emerges earlier in development if the rat is given prior fear conditioning to a different stimulus. Some constraints of this "facilitation" effect are determined in follow-up experiments. This facilitation effect may provide a novel way of testing the development of the neural circuits underlying learned fear. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
49.
Abstract: The aim of this paper is to describe a system whereby an intensive care unit patient's condition can be monitored and assessed over time using mostly blood gas analysis data. The first six sections analyse some major temporal reasoning approaches (with limited examples from other related areas) with the aim of selecting one for the task at hand. The last sections describe the PONJIP temporal blood gas analysis expert system with its main components, including user interfaces customised to the doctor's requirements. Since the overall aim of this paper is to describe an expert system used for the evaluation of the possible contribution of temporal medical reasoning from blood gas data, research specific to other application areas or data will not be covered here. 相似文献
50.
The trypan blue exclusion test, the MTT test and an immunostaining test for apoptosis were performed before and after incubation of SW620 human colonic carcinoma cells with different cytotoxic agents (CTAs) in order to assess tumor cell viability and CTA efficacy in vitro. A modified MTT test using light microscopy was also performed. A good correlation was found between the trypan blue assay and the MTT test, as determined by spectrophotometry. There was no 'overestimation' of cell viability as measured by the trypan blue test. The monitoring of formazan formation by light microscopy was feasible, but not very reliable since it did not show a good correlation with findings determined by spectrophotometry. The apoptosis test failed to show good correlation with other tests. Distilled water had no relevant cytotoxic effect, while chlorhexidine cetrimide (HAC 3.5%), chloramine 0.5% and polyvinylpyrrolidone iodine (PVP-I) > or = 0.05% damaged a large majority of cells. PVP-I at a concentration of > or = 5% was found to be the most effective CTA. 相似文献