全文获取类型
收费全文 | 10368篇 |
免费 | 852篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 128篇 |
综合类 | 12篇 |
化学工业 | 2597篇 |
金属工艺 | 310篇 |
机械仪表 | 601篇 |
建筑科学 | 178篇 |
矿业工程 | 5篇 |
能源动力 | 502篇 |
轻工业 | 918篇 |
水利工程 | 25篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 1779篇 |
一般工业技术 | 2275篇 |
冶金工业 | 558篇 |
原子能技术 | 110篇 |
自动化技术 | 1228篇 |
出版年
2024年 | 12篇 |
2023年 | 129篇 |
2022年 | 178篇 |
2021年 | 340篇 |
2020年 | 277篇 |
2019年 | 313篇 |
2018年 | 320篇 |
2017年 | 359篇 |
2016年 | 396篇 |
2015年 | 381篇 |
2014年 | 528篇 |
2013年 | 702篇 |
2012年 | 789篇 |
2011年 | 834篇 |
2010年 | 625篇 |
2009年 | 574篇 |
2008年 | 603篇 |
2007年 | 448篇 |
2006年 | 383篇 |
2005年 | 363篇 |
2004年 | 306篇 |
2003年 | 302篇 |
2002年 | 262篇 |
2001年 | 196篇 |
2000年 | 175篇 |
1999年 | 185篇 |
1998年 | 258篇 |
1997年 | 180篇 |
1996年 | 160篇 |
1995年 | 109篇 |
1994年 | 74篇 |
1993年 | 77篇 |
1992年 | 49篇 |
1991年 | 40篇 |
1990年 | 41篇 |
1989年 | 36篇 |
1988年 | 35篇 |
1987年 | 35篇 |
1986年 | 13篇 |
1985年 | 29篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1974年 | 7篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
31.
Teik-Cheng Lim 《Journal of Materials Science》2004,39(15):4965-4969
32.
33.
Kwang-Hee Lim 《Korean Journal of Chemical Engineering》2005,22(2):228-233
An experiment for five stages of a biofilter-run was performed to investigate the effect of hydrophilic ethanol and hydrophobic
toluene on the biodegradation of hydrophobic toluene and hydrophilic ethanol, respectively, when waste-air containing toluene
and ethanol was treated by a biofilter. Removal efficiencies of toluene and ethanol began to decrease when inlet load surpassed
90 g/m3/h and 100 g/m3/h consistent with maximum elimination capacities of toluene and ethanol, respectively. At the end of the biofilter-run, removal
efficiencies for toluene and ethanol were decreased and maintained at 65% and 40%, respectively. The concentration of toluene
at 1st sampling port was raised by factor of two in the 3rd stage of the biofilter run when the inlet load of ethanol co-feed
was increased by 1.5 times, while the process conditions of toluene were maintained the same as those of the 2nd stage of
biofilter-run. According to the result of Mohseni and Allen, it may be interpreted that removal efficiency of hydrophobic
toluene was affected by the presence of hydrophilic ethanol when high load of hydrophobic toluene was applied like that of
the 1st sampling port of the biofilter. However it was not the case when a low load of hydrophobic toluene was applied like
those of the 2nd, 3rd and 4th sampling ports since hydrophobicity of toluene is much less that of α-pinene. Thus, it may be
suggested that biodegradation of hydrophobic VOC was interfered by hydrophilic VOC dissolved in the biolayer and the degree
of interference was proportional to the inlet load of hydrophobic VOC as well as that of hydrophilic VOC and was inversely
proportional to the solubility of hydrophobic VOC. However, it was inferred that the existence of hydrophobic toluene from
waste-air can hardly inversely hinder the removal of hydrophilic ethanol in the biofilter when timeevolutions of hydrophilic
ethanol concentrations of this experiment were compared with those of the previous experiment of biofilter to treat waste-air
containing ethanol only. 相似文献
34.
Chun Yang Yin Sharifah Aishah Syed Abdul KadirYing Pei Lim Sharifah Nawirah Syed-AriffinZurinawati Zamzuri 《Fuel Processing Technology》2008
Ash derived from combustion of Malaysian oil palm biomass (empty fruit bunches consisting of fibers) was physically and chemically characterized in order to provide a comprehensive understanding of its specific properties in terms of toxicity, compositions and reusability. Principal analyses conducted include particle size distribution, scanning electron microscopy, elemental dispersive X-ray, elemental analysis, toxicity characteristic leaching procedure (TCLP) as well as thermogravimetric, X-ray diffractometry and Fourier-transform infrared analyses. TCLP result indicated that the oil palm ash (OPA) should not be classified as toxic wastes in terms of heavy metal leachability since leachable copper, cadmium, lead and nickel concentrations were detected below the stipulated leachability limits. It was determined that the OPA contained high amount of potassium as well as presence of silica which implied its suitability to be reused as crude fertilizer or cement replacement material. 相似文献
35.
Rajoo R. Lim S.S. Wong E.H. Hnin W.Y. Seah S.K.W. Tay A.A.O. Iyer M. Tummala R.R. 《Advanced Packaging, IEEE Transactions on》2008,31(2):377-385
A wafer level packaging technique has been developed with an inherent advantage of good solder joint co-planarity suitable for wafer level testing. A suitable weak metallization scheme has also been established for the detachment process. During the fabrication process, the compliancy of the solder joint is enhanced through stretching to achieve a small shape factor. Thermal cycling reliability of these hourglass-shaped, stretch solder interconnections has been found to be considerably better than that of the conventional spherical-shaped solder bumps. 相似文献
36.
Myung-Sun Baek Hyung-Joon Kook Mi-Jeong Kim Young-Hwan You Hyoung-Kyu Song 《Broadcasting, IEEE Transactions on》2005,51(4):551-559
In this paper, we apply multi-antenna scheme to DAB system for high-rate transmission. In the MIMO-DAB system with a number of transmitting and receiving antennas increases the transmission rate efficiently with low multiplication operations. For channel estimation in the MIMO-DAB system, we propose a new PRS structure and evaluate the channel estimation performance. The proposed PRS structure can estimate multi-channel information based on the semi-blind processing. The performance of proposed PRS is compared with that of conventional training sequence employing Tarokh's transmission matrix. And also we investigate the performance limitation due to the imperfect channel estimation in a MIMO-DAB receiver. It has been shown that the MIMO-DAB system with multi-antennas can achieve the high-rate transmission for multimedia broadcasting and the performance of MIMO-DAB system is impaired by imperfect channel information. 相似文献
37.
Joonho Lim Kipaek Kwon Soo-Ik Chae 《Electronics letters》1998,34(4):344-346
The authors propose a reversible energy recovery logic (RERL) circuit for ultra-low-energy consumption, which consumes only adiabatic energy loss and leakage current loss by completely eliminating non-adiabatic energy loss. It is a dual-rail adiabatic circuit using the concept of reversible logic with a new eight-phase clocking scheme. Simulation results show that at low-speed operation, the RERL consumes much less energy than the complementary static CMOS circuit and other adiabatic logic circuits 相似文献
38.
39.
Characterization of the cavity nucleation factor for life prediction under creep-fatigue interaction
Baig Gyu Choi Soo Woo Nam Young Cheol Yoon Joong Jae Kim 《Journal of Materials Science》1996,31(18):4957-4966
It is understood that grain boundary cavitation is one of the detrimental processes for the degradation of materials that reduces the creep-fatigue life at high temperatures. In a previous investigation, a model for life prediction under creep-fatigue conditions was proposed in terms of cavity nucleation and growth. In that model, the cavity nucleation factor (P) was introduced to correlate between the number of cavities and the plastic strain range from which athermal vacancies are generated. It was considered to be a material specific constant which was independent of the experimental conditions. However, in this study, it is found that the cavity nucleation factor is a function of the plastic strain range but is independent of the testing temperature at near 0.5 T
m. In the light of this dependency, a new cavity nucleation factor (P'), is introduced. Using this new cavity nucleation factor (P'), a modified equation for life prediction is proposed, and it is shown that there is good agreement between predicted and experimental lives. Additionally, an interesting approach has been made to find the physical meaning of the new cavity nucleation factor (P'). According to this study, it is suggested that the new cavity nucleation factor, which is regarded as a material specific constant, is found to be strongly related to the density of the grain boundary precipitates with a linear relationship existing between them. 相似文献
40.
The incidence of stress fractures is increasing among competitive and recreational athletes as well as among children and the elderly. By understanding the continuum of bone's response to stress and maintaining an appropriate index of suspicion, the health care provider can diagnose these injuries appropriately. An accurate history and examination is essential and will differentiate stress fractures from other stress reactions. The more common stress fractures are discussed. 相似文献