全文获取类型
收费全文 | 1361篇 |
免费 | 60篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 488篇 |
金属工艺 | 39篇 |
机械仪表 | 42篇 |
建筑科学 | 26篇 |
矿业工程 | 2篇 |
能源动力 | 63篇 |
轻工业 | 90篇 |
水利工程 | 11篇 |
石油天然气 | 14篇 |
无线电 | 138篇 |
一般工业技术 | 218篇 |
冶金工业 | 89篇 |
原子能技术 | 8篇 |
自动化技术 | 183篇 |
出版年
2024年 | 5篇 |
2023年 | 23篇 |
2022年 | 45篇 |
2021年 | 59篇 |
2020年 | 38篇 |
2019年 | 38篇 |
2018年 | 68篇 |
2017年 | 57篇 |
2016年 | 53篇 |
2015年 | 41篇 |
2014年 | 54篇 |
2013年 | 101篇 |
2012年 | 72篇 |
2011年 | 65篇 |
2010年 | 64篇 |
2009年 | 60篇 |
2008年 | 46篇 |
2007年 | 41篇 |
2006年 | 27篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 20篇 |
2002年 | 30篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 21篇 |
1998年 | 34篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 20篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 5篇 |
排序方式: 共有1429条查询结果,搜索用时 31 毫秒
1.
2.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
3.
N. E. Wijeysundera M. N. A. Hawlader Chan Wee Boon Andy M. Kamal Hossain 《International Journal of Refrigeration》2004,27(5):1997
An ice slurry generation system was developed using direct contact heat transfer between water and the coolant, Fluroinert FC-84. The location of the coolant nozzle is an important design consideration to avoid clogging due to freezing of water. An ice fraction of up to about 40 percent was obtained with the nozzle located at the bottom of the ice slurry tank and the jet directed upwards into the water. Two simplified model were developed to extract the heat transfer coefficient between the coolant drops and the water. The first model requires as input the average drop diameter and the residence time while the second model uses the measured drop diameter distribution. The estimated heat transfer coefficients are much smaller than those computed using single-sphere correlations. 相似文献
4.
A generalized equation was derived to calculate the melting temperatures of homopolymers and copolymers. The Gibbs‐Thomson equation for homopolymers and a modified application to copolymers were derived using the proposed equation. The melting temperature Tm0 in the Flory equation corresponds to the melting temperature TmC,∞ of copolymer crystals with stems of infinite length. Also, TmC,n*, the melting temperature for copolymer crystals with stems containing the maximum possible number of structural units, n*, should be used instead of Tm0 as the basis of supercooling in crystallization. The proposed equation shows good agreement with experimental data for α‐alkene‐ethylene homogeneous copolymers. 相似文献
5.
6.
Ulla I. Brimberg Afaf Kamal‐Eldin 《European Journal of Lipid Science and Technology》2003,105(2):83-91
The influence of minor amounts of pro‐ and anti‐oxidants on the kinetics of the autoxidation of fat has been evaluated. The reaction rates of oxygen with the substrates were found to follow the same basic equation, hitherto established for pure substrates. There is evidence that the surface of the reaction vessel also acts as a reaction catalyst and its effect is proportional to the area of glass in contact with lipids. Oxidation is enhanced by trace metal ions as well as by surface‐active compounds (e.g. hydroperoxides and sterols). Antioxidants such as α‐tocopherol and butylated hydroxyanisole inhibit the oxidation by delaying the start of oxygen consumption (the induction period) while retarders like amino acids only decrease the rate of oxidation. Thus pro‐ and anti‐ oxidants affect either the start or the rate of oxygen consumption. The empirical formula dx/dt = k [O2] (1‐x/n) f′(t) was found applicable to the different stages of oxidation. 相似文献
7.
A 2-year-old boy with Rotor syndrome was studied with Tc-99m N-(di-isopropylphenyl carbamoylmethyl) iminodiacetic acid (DIPA). In this patient, the liver was not visualized, and there was persistent visualization of the cardiac blood pool and along with prominent kidney excretion. It is concluded that Tc-99m DIPA cholescintigraphy may be helpful in the diagnosis of Rotor syndrome. 相似文献
8.
The gene rafY from the plasmid pRSD2, which enables Escherichia coli to grow on raffinose, was transferred into expression plasmid pUSL77. The protein was expressed in the porin-deficient Escherichia coli strain KS26 and was isolated and purified to homogeneity. The pure protein was reconstituted into lipid bilayer membranes. It formed an ion-permeable channel with a single-channel conductance of 2.9 nS of the open state in 1 M KCl, which is approximately twice of that of the general diffusion pores OmpF and OmpC of E. coli outer membrane. At lower pH the channel exhibited rapid flickering between three substates of the open channel. The RafY channel appears to be wide and water filled and has a small selectivity for cations over anions. Although RafY is part of an uptake and fermentation system for raffinose it does not contain a binding site for carbohydrates. Our results suggest that RafY is a general diffusion pore with a diameter, larger than that of the general diffusion porins OmpF and OmpC, that allows the diffusion of high-molecular-mass carbohydrates through the outer membrane. 相似文献
9.
Zamli Kamal Z. Kader Abdul Din Fakhrud Alhadawi Hussam S. 《Neural computing & applications》2021,33(23):16641-16658
Neural Computing and Applications - Cryptography often involves substituting (and converting) the secret information into dummy data so that it could reach the desired destination without leakage.... 相似文献
10.
Kader Md. Abdul Zamli Kamal Z. Ahmed Bestoun S. 《Neural computing & applications》2021,33(23):15933-15953
Neural Computing and Applications - Emperor Penguin Optimizer (EPO) is a recently developed metaheuristic algorithm to solve general optimization problems. The main strength of EPO is twofold.... 相似文献