全文获取类型
收费全文 | 656篇 |
免费 | 14篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 42篇 |
综合类 | 1篇 |
化学工业 | 135篇 |
金属工艺 | 24篇 |
机械仪表 | 16篇 |
建筑科学 | 19篇 |
能源动力 | 26篇 |
轻工业 | 49篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 28篇 |
一般工业技术 | 113篇 |
冶金工业 | 106篇 |
原子能技术 | 34篇 |
自动化技术 | 79篇 |
出版年
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 9篇 |
2014年 | 16篇 |
2013年 | 29篇 |
2012年 | 27篇 |
2011年 | 37篇 |
2010年 | 19篇 |
2009年 | 30篇 |
2008年 | 22篇 |
2007年 | 29篇 |
2006年 | 27篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 44篇 |
1997年 | 32篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有676条查询结果,搜索用时 0 毫秒
81.
82.
A rechargeable solid electrolyte cell has been developed using a high copper-ion-conductivity solid electrolyte, Rb4Cu16I7–Cl13+, a copper anode, and an intercalation cathode, TiS2. The open-circuit voltage was 0.59 V at 25° C. The cell yielded a current of several tens of microamperes at room temperature without appreciable polarization. The cell could be submitted to one hundred or more charge-discharge cycles without showing appreciable deterioration. 相似文献
83.
The design and fabrication of a GaAs varactor diode for u.h.f. t.v. tuners were carried out using a GaAs double epitaxial layer. The capacitance ratio of diode. C3/C25, is 6.0 and the series resistance at 470 MHz is 0.24 ?. These characteristics are much better than those of an Si diode and well satisfy the requirements for t.v. tuners. 相似文献
84.
The concentration of the bare metal ions located in the Site II of the alkaline-earth Y zeolites was determined from the CO adsorption, and the concentration sequence was obtained as follows: SrY>CaY>MgY>BeY. This sequence corresponded well to the radius of exchanged cation. Catalytic activity of alkaline-earth Y zeolites for the disproportionation reaction of NO, further, was discussed, and activity order of per unit amount of bare Site II cation was determined as follows: BeY>MgY>CaY>SrY>BaY. This order corresponded well to the strength of the electrostatic field of alkaline-earth Y zeolites. 相似文献
85.
Hosomi N Kawamura-Konishi Y Kawano R Fujii I Suzuki H 《Journal of Bioscience and Bioengineering》2005,99(3):222-229
Monoclonal antibody 2D7 generated against a transition-state analog N-methyl mesoporphyrin catalyzes a reaction for insertion of a cupric ion into mesoporphyrin. To investigate amino acid residues responsible for the catalytic activity, site-directed mutagenesis of the amino acid residues in the third complementarity determining region of the heavy chain (CDRH3) was performed on the antigen-binding fragment (Fab) of the antibody. Recombinant Fab mutants, in which Arg95 is replaced with Ala (R95A), Asp96 with Asn (D96N) and Met97 with Gly (M97G), were examined in terms of the catalytic efficiency of the reaction (k/K(S)) and the dissociation constant for N-methyl mesoporphyrin binding (K(d)) and these values were compared with those of the wild type. The k/K(S) values of the R95A and D96N mutants were 0.96% and 1.0% of that of the wild type, respectively, whereas the M97G mutant had no detectable catalytic activity. The K(d) values of the R95A and D96N mutants were 165 and 69 times that of the wild type, respectively, while that of the M97G mutant was similar to that of the wild type. The relationship between the k/K(S) and 1/K(d) values in the wild type and the R95A and D96N mutants suggests that Arg95 and Asp96 are responsible for stabilizing the transition-state in the catalytic reaction. The results of the M97G mutant allow us to propose that Met97 plays an important role in the catalytic activity probably due to a subtle and specific conformation of the antibody. 相似文献
86.
Yasuhiko Takemoto Ikuo Arizono 《The International Journal of Advanced Manufacturing Technology》2005,25(11-12):1205-1210
Recently, Chou et al. [11] have considered the multivariate control chart for monitoring the process mean vector and covariance matrix for the related quality characteristics simultaneously by using log-likelihood ratio statistics. They have computed the approximation formula described with Bernoulli polynomials of degrees r≥30 by using software MATHEMATICA 4.0 for obtaining the control limit with sufficient accuracy for the specified type I error probability in the chart. However, they cannot have obtained the approximation formula for the power evaluation. By the way, Kanagawa et al. [12] have proposed the $(\bar{x},s)$ control chart for monitoring the mean and variance simultaneously based on Kullback–Leibler information when quality characteristics obey a univariate normal distribution. In this article, by adopting the procedure by Kanagawa et al., we propose the other approximation formula for determining simply the control limit with sufficient accuracy for the specified type I error probability. Furthermore, the power evaluation for the chart is also considered in theory. 相似文献
87.
88.
Jin-ichi Nakamura Yoichi Takahashi Shin-ichiro Izumi Masayoshi Kanno 《Journal of Nuclear Materials》1980,88(1):64-72
The heat capacities of metallic uranium and thorium from 80 to 1000 K have been determined by laser-flash calorimetry. The results on uranium agree very well with those in the literature over the temperature range investigated. The results on thorium are several percent lower than the heat-capacity values hitherto reported, while the enthalpy data at high temperatures in the literature are in good agreement with the present results. Shomate's analysis showed that the present results are the most consistent through the temperature range from 80 to 1000 K. On this, a revised table of thermodynamic functions of thorium from 80 to 1000 K is presented. The excess heat capacity on thorium has been found to be not appreciable up to 1000 K, in contrast with the large excess heat capacity above 300 K for uranium. 相似文献
89.
90.
Mismatch repair genes are involved in increasing the fidelity of replication by specific repair of DNA polymerase incorporation errors. In Escherichia coli, the best studied mismatch repair (MMR) pathway is the methyl-directed long patch repair system which is mediated by three gene products; MutS, MutL and MutH. These are conserved in higher eukaryotes. Mutations in human homologues of these proteins have been shown to be implicated in hereditary non-polyposis colorectal cancer (HNPCC). Alterations in the coding regions of MMR genes result in a mutator phenotype with marked instability of microsatellite sequences, indicative of a deficiency in DNA repair. 相似文献