全文获取类型
收费全文 | 460篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 56篇 |
金属工艺 | 31篇 |
机械仪表 | 3篇 |
建筑科学 | 5篇 |
能源动力 | 6篇 |
轻工业 | 51篇 |
无线电 | 99篇 |
一般工业技术 | 77篇 |
冶金工业 | 97篇 |
原子能技术 | 5篇 |
自动化技术 | 14篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 14篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 18篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 20篇 |
2004年 | 16篇 |
2003年 | 25篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 13篇 |
1999年 | 29篇 |
1998年 | 31篇 |
1997年 | 22篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有465条查询结果,搜索用时 31 毫秒
1.
Rinji Akada Yoshirou Shimizu Yuji Matsushita Miho Kawahata Hisashi Hoshida Yoshinori Nishizawa 《Yeast (Chichester, England)》2002,19(1):17-28
Drug-resistance markers for yeast transformation are useful because they can be applied to strains without auxotrophic mutations. However, they are susceptible to technical difficulties, namely lower transformation efficiency and the appearance of drug-resistant mutants without the marker. To avoid these problems, we have constructed a phosphoglycerate kinase (PGK) promoter-driven YAP1 expression cassette, called PGKp-YAP1. Yeast cells containing PGKp-YAP1 were resistant to cycloheximide, a protein synthesis inhibitor, and also to cerulenin, a fatty acid synthesis inhibitor, but not to other drugs tested. The transformation efficiency of PGKp-YAP1 using cerulenin selection was comparable to that using a URA3 auxotrophic marker when low concentrations of cerulenin were used. Non-transformed drug-resistant colonies did appear on the low-concentration cerulenin plates. However, these non-transformed colonies could easily be identified, based on their cycloheximide sensitivity and/or their resistance to aureobasidin A to which the transformants were sensitive. Therefore, the dual drug resistance of PGKp-YAP1 could be used as an effective selection for PGKp-YAP1 recipient cells. The PGKp-YAP1 marker was used to disrupt the LYS2 gene and to transform an industrial yeast strain, indicating that this marker can be used for efficient and reliable gene manipulations in any Saccharomyces cerevisiae strain. 相似文献
2.
3.
The effect of mixing time on hardness, disintegration time and ejection force in tablettlng of magnesium stearate and lactose granules was studied. The hardness of the tablets decreased with an increase in mixing time of the blends, as previously reported. A semilogarithmic plot of the hardness versus mixing time gave a straight line having a turning point. At the early phase of mixing the hardness was decreasing with a large first-order rate and then continued to decrease with another small first-order rate. The change in disintegration time or ejection force versus mixing time was basically the same as that in the hardness. This type of plot was applicable to the mixing magnesium stearate with not only granular but also powdered materials. 相似文献
4.
GaP-AlGaP waveguide semiconductor Raman amplifiers (SRAs) tapered on both sides were fabricated by high-quality GaP-AlGaP liquid phase epitaxial growth using the temperature difference method with controlled vapor pressure (TDM-CVP), photolithography patterning, and reactive ion etching with PCl/sub 3/ gas. Although the finesse of the both-sides-tapered waveguide SRA is lower than previous values for straight or one-side-tapered waveguides, the CW-pumped gain was maximized, and a maximal gain of 4.2 dB was obtained. This letter presents the effect of tapered structures in SRA with CW pumping amplification. 相似文献
5.
Shoji Noda Haruo Doi Tatsumi Hioki Jun-Ichi Kawamoto Osami Kamigaito 《Journal of Materials Science》1987,22(12):4267-4273
Single-crystal alumina was implanted firstly with 400 keV Si+ and subsequently with N2
+ ions and then annealed at 1673 K in an No atmosphre. The implanted layers were characterized by means of X-ray diffraction, Rutherford backscattering-channelling of 2 MeV He+ ions, and the resonance nuclear reaction15N(p,)12C. The annealing of sapphire implanted at ambient temperature resulted in the formation of-sialon, a solid solution of-silicon nitride and alumina in the subsurface layer, while implantation at 100 K resulted in the formation of aluminium oxynitride in the surface layer. In the latter case, the implanted silicon atoms were believed not to react vxi1h the implanted nitrogen atoms but with the substrate oxygen atoms. These crystalline precipitates were found to have epitaxial relations with the sapphire substrate. 相似文献
6.
Takeo Hattori Atsushi Shigemori Jun-Ichi Mohri Masahiro Yoshimura Shigeyuki Somiya 《Journal of the American Ceramic Society》1982,65(9):c142-c142
Powder compacts of synthetic mica (fluorphlogopite) encapsulated in a boro–silicate glass tube were isostatically hot–pressed in a Roy–Tuttle–type pressure vessel. Synthetic mica was sintered to a density of 2.60 g/cm3 (91.2% of theoretical density) without additives under 98 MPa of water at 800°C for 45 min. 相似文献
7.
8.
Toshiro Hirai Jun-Ichi Yamaki Akihiko Yamaji 《Journal of Applied Electrochemistry》1985,15(3):441-445
To improve the performance of air electrodes, the dependence of iron phthalocyanine (FePc) catalytic effects on preparation methods was examined. The methods used were mixture (Electrode 1), impregnation (Electrode 2) and direct synthesis (Electrode 3). Electrodes 2 and 3 showed higher potentials during cathodic polarization up to 10 mA cm–2 than Electrode 1. The rate of chemical destruction of H2O2 decreased in the order Electrode 3 > Electrode 2 > Electrode 1. Electrode 3 showed the smallest potential drop for a discharge at 10 mA cm–2, 0.09 V after 50 h. However, the potential of Electrode 2 decreased with discharge, becoming 0.09 V lower than that of Electrode 3 after a 50 h discharge at 10mA cm–2. Once the potential drop occurred, the potential was not recovered by resting or by drying the electrode. The potential drop may be caused by deactivation of FePc. One possible reason for such deactivation is the presence of H2SO4, which remained on the electrode after impregnation of the FePc-H2SO4 solution. 相似文献
9.
K. Nishizawa H. Kato K. Mimori T. Yoshida N. Hasegawa M. Tsuji Y. Tamaura 《Journal of Materials Science》1994,29(3):768-772
Methanation reactivity was studied for the surface carbon deposited from CO2 on the surface of Rh-bearing activated magnetite. The most active material (Rh=0.83 wt %) for methanation was prepared by the impregnation method at 60°C and showed 98% conversion at 300°C. The surface carbon was composed of elemental carbon (-carbon) and polymerized carbon (-carbon), the proportion being dependent on the density of carbon deposited. In temperature-programmed surface reaction, the extent of conversion of the - and -carbon to CH4 was 0.34 (-carbon) and 0.53 (-carbon), respectively, and the total conversion was 0.87. This result indicates that not only elemental carbon but polymerized carbon (-carbon) could be converted to CH4 on the Rh-bearing activated (-carbon) magnetite, whereas -carbon is not hydrogenated on activated magnetite. 相似文献
10.