全文获取类型
收费全文 | 1010篇 |
免费 | 27篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 78篇 |
综合类 | 7篇 |
化学工业 | 304篇 |
金属工艺 | 41篇 |
机械仪表 | 23篇 |
建筑科学 | 30篇 |
矿业工程 | 2篇 |
能源动力 | 50篇 |
轻工业 | 63篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 53篇 |
一般工业技术 | 160篇 |
冶金工业 | 89篇 |
原子能技术 | 48篇 |
自动化技术 | 85篇 |
出版年
2022年 | 7篇 |
2021年 | 20篇 |
2020年 | 5篇 |
2019年 | 16篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 38篇 |
2013年 | 67篇 |
2012年 | 32篇 |
2011年 | 69篇 |
2010年 | 51篇 |
2009年 | 36篇 |
2008年 | 40篇 |
2007年 | 60篇 |
2006年 | 44篇 |
2005年 | 41篇 |
2004年 | 27篇 |
2003年 | 44篇 |
2002年 | 28篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 23篇 |
1998年 | 40篇 |
1997年 | 19篇 |
1996年 | 21篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有1040条查询结果,搜索用时 531 毫秒
1.
2.
Y Terashima H Ozaki R R Giri T Tano S Nakatsuji R Takanami S Taniguchi 《Water science and technology》2006,54(8):55-63
Environmental pollution by low concentrations of 2,4-Dichlorophenoxyacetic acid (2,4-D) is a concern these days due to ever increasingly stringent regulations. Photocatalysis with immobilized TiO2 fiber is a promising oxidation method. Laboratory experiments on photocatalytic degradation of 0.045 mmol l(-1) 2,4-D with the world's first high-strength TiO2 fiber catalyst were carried out in a continuous flow reactor in which the degradations were, in general, similar to those with high 2,4-D concentrations investigated elsewhere. Degradation and mineralization of 2,4-D were significantly enhanced with no initial pH adjustments. The rate constants for total organic carbon (TOC) without pH adjustment were about two-fold bigger than the pH adjustment cases. CO2 gas measurement and carbon mass-balance were carried out for the first time, where about 34% organic carbon converted into CO2 gas during four-hour oxidation. 2,4-Dichlorophenol (2,4-DCP), phenol, benzyl alcohol and two unknowns (RT = 2.65 and 3.78 min.) were detected as aromatic intermediates while Phenol was the new aromatic in HPLC analysis. Dechlorination efficiencies were high (> 70%) in all the cases, and more than 90% efficiencies were observed in chloride mass balance. Bigger flow rates and solution temperature fixed at 20 degrees C without pH adjustment greatly enhanced 2,4-D mineralization. These results can be an important basis in applying the treatment method for dioxin-contaminated water and wastewater. 相似文献
3.
4.
Kazuyoshi Kataoka Kazuo Furuta Yoshiaki Oka Shunsuke Kondo 《Nuclear Engineering and Design》1988,110(1)
Transmutation of neptunium, which is contained in radioactive wastes discharged from nuclear reactors, was investigated as a substitutional method for geologic disposal. We proposed a transmutation reactor fueled with a mixture of gaseous 233UF6 and 237NpF6. Neutronic and thermodynamic analysis of the reactor revealed the feasibility of the concept. The reactor has two principal advantages: (1) use of the fuel gas enables on-line reprocessing, (2) 237Np can be transmuted by a high neutron flux. Our calculation indicated that the transmutation rate of 237Np was 335 g/year/MWth, which is much larger than the annual yield of 232Np in PWR (6.19 g/year/MWth). 相似文献
5.
Lipid-Lowering Effect of Eriocitrin, the Main Flavonoid in Lemon Fruit, in Rats on a High-Fat and High-Cholesterol Diet 总被引:2,自引:0,他引:2
Yoshiaki Miyake Eriko Suzuki Satoko Ohya Syuichi Fukumoto Masanori Hiramitsu Kazuhiro Sakaida Toshihiko Osawa Yukio Furuichi 《Journal of food science》2006,71(9):S633-S637
ABSTRACT: Eriocitrin (eriodictyol 7- O -β-rutinoside) is the main flavonoid in lemon fruit. In this study, eriocitrin was investigated for its lowering effect on serum and hepatic lipids in high-fat and high-cholesterol fed rats. Rats in the control group ( N = 6) were fed a 20% lard and 1% cholesterol diet for 21 d, and rats in the 0.35% eriocitrin group ( N = 6) and 0.70% eriocitrin group ( N = 6) were fed a diet supplemented with eriocitrin 0.35% and 0.70%, respectively. The content of hepatic total cholesterol and triglyceride in the eriocitrin group was no different from that of the control group. The total cholesterol, VLDL+LDL, triglyceride, and phospholipid in the serum of the 0.35% eriocitrin group showed significantly lower concentrations than the control group ( P < 0.05), although there was no difference in the HDL concentrations among the groups. The lowering effect of eriocitrin for serum total cholesterol was thought to be caused by a decrease in VLDL+LDL. The 0.35% eriocitrin group was shown to have a significant increase in excretion of fecal bile acid ( P < 0.05) and a tendency for enhanced hepatic m-RNA levels of LDL receptor in comparison with the control group. 相似文献
6.
Tsuyoshi Takahashi Masahito Kitou Michio Asai Mitsuyasu Kido Tomio Chiba Junzou Kawakami Yoshiaki Matsui 《Electrical Engineering in Japan》1994,114(2):18-33
Power system control equipment needs higher sensitivity and operational reliability. Advanced voltage control equipment is needed for reducing the frequency of tap changes and improving the characteristics (the relationship between the actual voltage and reference voltage) of the voltage to meet today's power system requirements. However, these objectives are in a trade-off relationship. Studies of voltage control derived from a knowledge base suitable for electric power systems can satisfy these objectives using fuzzy inference. Compared with corresponding conventional equipment, the new equipment improved the deviation of 30 min average voltage of 30 percent. This paper describes the design concept of new voltage control equipment using fuzzy inference. In addition, field test results are described along with rules of fuzzy inference, membership functions, and the deviation of 30 min average voltage through detailed simulation. 相似文献
7.
Hideaki Yamada Akiyoshi Chayahara Yoshiaki Mokuno Shin-ichi Shikata 《Diamond and Related Materials》2008,17(4-5):494-497
A new structure of microwave plasma for chemical vapor deposition of diamond crystal is proposed. The structure is designed numerically, for which an improved model given in our previous work [H. Yamada et al., J. Appl. Phys. 101 (2007), art. no. 063302.] is utilized. The experimental observations and numerical predictions agree well with each other. It is demonstrated experimentally that the proposed structure can achieve a growth rate larger than 50 μm/h over an area 1 in. in diameter. 相似文献
8.
9.
Mio Yamaguchi Kiyoshi Takagi Koki Narita Yasuhiro Miki Yoshiaki Onodera Minoru Miyashita Hironobu Sasano Takashi Suzuki 《International journal of molecular sciences》2021,22(4)
Chemokines secreted from stromal cells have important roles for interactions with carcinoma cells and regulating tumor progression. C-C motif chemokine ligand (CCL) 5 is expressed in various types of stromal cells and associated with tumor progression, interacting with C-C chemokine receptor (CCR) 1, 3 and 5 expressed in tumor cells. However, the expression on CCL5 and its receptors have so far not been well-examined in human breast carcinoma tissues. We therefore immunolocalized CCL5, as well as CCR1, 3 and 5, in 111 human breast carcinoma tissues and correlated them with clinicopathological characteristics. Stromal CCL5 immunoreactivity was significantly correlated with the aggressive phenotype of breast carcinomas. Importantly, this tendency was observed especially in the CCR3-positive group. Furthermore, the risk of recurrence was significantly higher in the patients with breast carcinomas positive for CCL5 and CCR3 but negative for CCR1 and CCR5, as compared with other patients. In summary, the CCL5-CCR3 axis might contribute to a worse prognosis in breast cancer patients, and these findings will contribute to a better understanding of the significance of the CCL5/CCRs axis in breast carcinoma microenvironment. 相似文献
10.
The feeding and gustatory responses to ecdysone and 20-hydroxyecdysone were investigated in the silkworm,Bombyx mori. 20-Hydroxyecdysone reduced feeding response strongly in fourth- and fifth-instar larvae, whereas ecdysone had no effect on feeding response. 20-Hydroxyecdysone stimulated the R receptor, the receptor to feeding deterrents, to a great degree. By contrast, ecdysone was much less effective for stimulating the R receptor. These results indicate that ecdysone and 20-hydroxyecdysone have different effects on feeding response due to different interactions with mouthpart chemoreceptors. 相似文献