全文获取类型
收费全文 | 1546篇 |
免费 | 26篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 114篇 |
综合类 | 4篇 |
化学工业 | 397篇 |
金属工艺 | 34篇 |
机械仪表 | 52篇 |
建筑科学 | 42篇 |
能源动力 | 55篇 |
轻工业 | 117篇 |
水利工程 | 3篇 |
无线电 | 89篇 |
一般工业技术 | 223篇 |
冶金工业 | 278篇 |
原子能技术 | 69篇 |
自动化技术 | 98篇 |
出版年
2022年 | 13篇 |
2021年 | 29篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 12篇 |
2014年 | 26篇 |
2013年 | 74篇 |
2012年 | 40篇 |
2011年 | 51篇 |
2010年 | 60篇 |
2009年 | 69篇 |
2008年 | 71篇 |
2007年 | 58篇 |
2006年 | 49篇 |
2005年 | 53篇 |
2004年 | 40篇 |
2003年 | 37篇 |
2002年 | 53篇 |
2001年 | 18篇 |
2000年 | 29篇 |
1999年 | 44篇 |
1998年 | 97篇 |
1997年 | 74篇 |
1996年 | 55篇 |
1995年 | 38篇 |
1994年 | 50篇 |
1993年 | 44篇 |
1992年 | 25篇 |
1991年 | 23篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 27篇 |
1986年 | 27篇 |
1985年 | 22篇 |
1984年 | 19篇 |
1983年 | 16篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 19篇 |
1975年 | 8篇 |
1973年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有1575条查询结果,搜索用时 31 毫秒
61.
Toru Katsumata Hiromi Kubo Shuji Komuro Hiroaki Aizawa 《Journal of the American Ceramic Society》2014,97(6):1704-1707
Photoluminescence spectrum, trap depths, and densities of trapped carriers of CaAl2O4:Eu phosphor crystals doped with rare‐earth elements were studied using the thermally stimulated luminescence technique. Trap depths and densities of the specimens vary with rare‐earth elements doped as the auxiliary activators. Tm and Nd are found to be effective for the strong afterglow phosphorescence peaking at λ = 442 nm for several hours after the excitation. CaAl2O4:Eu phosphor crystals doped with Nd and Tm include high density of carriers trapped at E = 0.59 and 0.52 eV, respectively. 相似文献
62.
Microporous polypropylene sheets were prepared as follows. First, polypropylene pellet-containing CaCO3 filler was extruded to prepare base sheets, which were then biaxially stretched. The draft effect at the extrusion process was studied in relation to some properties of the resultant microporous polypropylene sheets. © 1996 John Wiley & Sons, Inc. 相似文献
63.
Yukio Mizutani 《应用聚合物科学杂志》1996,61(5):735-739
Acrylic acid and crosslinking agent [poly(ethylene glycol)-diacrylate or divinylbenzene] were copolymerized in benzene in the presence of layered sodium silicate (δ-Na2Si2O5) powder. The resultant poly(acrylic acid) complex shows large water absorbability, for which dependency on crosslinking degree was investigated. © 1996 John Wiley & Sons, Inc. 相似文献
64.
Microporous polypropylene fibers were prepared by stretching polypropylene fibers containing poly(methylsilsesquioxane) filler. The properties of the resultant fibers are controllable by adjusting the filler content and stretching degree. The resultant fibers have a fine texture of polypropylene fibrils, in which the filler particles are dispersed. Some properties were investigated: tensile strength, elongation, Young's modulus, porosity, pore size, and specific surface area. © 1996 John Wiley & Sons, Inc. 相似文献
65.
Toshio Fujii Hiroyuki Yoshimoto Naoshi Nagasawa Takayuki Bogaki Yukio Tamai Masaaki Hamachi 《Yeast (Chichester, England)》1996,12(6):593-598
The nucleotide sequences of alcohol acetyltransferase genes isolated from lager brewing yeast, Saccharomyces carlsbergensis have been determined. S. carlsbergensis has one ATF1 gene and another homologous gene, the Lg-ATF1 gene. There was a high degree of homology between the amino acid sequences deduced for the ATF1 protein and the Lg-ATF1 protein (75·7%), but the N-terminal region has a relatively low degree of homology. Southern analysis and contour-clamped homogeneous electric field analysis of Saccharomyces strains suggest that the ATF1 gene is located on chromosome XV in S. cerevisiae and that the Lg-ATF1 gene might originate from the ‘non-S. cerevisiae’ genome of S. carlsbergensis, which is similar to that of S. bayanus and S. pastorianus. The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL and GenBank data banks with the Accession Numbers D63449 (ATF1) and D63450 (Lg-ATF1). 相似文献
66.
单层网壳结构等效静风荷载分布估计 总被引:1,自引:1,他引:0
单层网壳对外荷载分布极为敏感,且稳定问题是其结构设计中的主要问题,因此风荷载分布的估计对其结构静力抗风分析非常重要。但目前常采用的等效静风荷载分布并不能有效反映其脉动分量对结构稳定性的可能不利影响。首先简单回顾了目前单层网壳抗风分析的方法,并介绍了一种基于风洞试验的有效风荷载分布估计方案。随后从稳定分析角度提出了一种新方法,可用来简单高效地估计单层网壳的有效风荷载分布,同时还可就风荷载的影响进行保守分析。最后,分别采用单层球面和柱面网壳作为算例,基于风洞试验结果,比较了不同估计方法在分析这类结构极限承载能力及稳定性问题时的效率,表明了所提出方法在单层网壳稳定分析中估计有效风荷载分布时的优点。 相似文献
67.
Shoji Eita Takahashi Ryuji Isogai Shosei Ito Naoto Kubo Masaki Tsukada Takao Fukuyama Hiroyuki 《Metallurgical and Materials Transactions B》2019,50(5):2454-2458
Metallurgical and Materials Transactions B - Normal spectral emissivity of molten Cu-Fe alloy with different compositions was measured at the wavelength of 807 nm using an electromagnetic... 相似文献
68.
Tanaka Y Taguchi S Yoshida S Hori S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(2):100-105
The effects of foods and chemicals related to food hygiene on degranulation were evaluated using a method for assaying the enzyme activity of beta-hexosaminidase as an index of chemical mediator release from RBL-2H3 cells in vitro. Using a previously developed assay system, we had found a large number of inhibitors and promoters of degranulation of RBL-2H3 cells. In the present study, we examined the inhibitory effect of zinc chloride on the degranulation (beta-hexosaminidase release) from RBL-2H3 cells with or without antigen in the presence of the degranulation-promotive chemicals, namely, 4 food additives, 7 pesticides and 2 veterinary drugs. These promotive chemicals were classified into two types on the basis of inhibitory profile by zinc chloride: 1) those which showed marked degranulation-inhibitory action when the cells were stimulated with antigen, such as butylhydroxyanisole, dibutylhydroxytoluene, EPN, cis- and trans-permethrin, prothiofos, pyridaben, terbufos, 2) those which showed marked degranulation-inhibitory action whether the cells were stimulated with antigen or not, such as butyl p-hydroxybenzoate, o-phenylphenol, bitertanol, salinomycin. In conclusion, zinc had a dramatic inhibitory effect on enhanced degranulation induced by synthetic chemicals in vitro. 相似文献
69.
Linda J. McPheron Steven J. Seybold Andrew J. Storer David L. Wood Toshikazu Ohtsuka Isao Kubo 《Journal of chemical ecology》1997,23(12):2825-2839
The aggregation pheromone produced by maleIps paraconfusus (Coleoptera: Scolytidae) tunneling in Monterey pine,Pinus radiata, logs was trapped on Porapak Q. A concentration of an extract of trapped volatiles that attracted beetles was determined in the laboratory through a concentration–response analysis of walking behavior of males and females. The interruptant effects of four concentrations of verbenone on response to a constant concentration of this naturally produced aggregation pheromone were tested with males and females. Independent of its enantiomeric composition [99.5% (S)-(–), 93.1 % (S)-(–), and 98.3% (R)-(+)], verbenone significantly reduced the percentage of females (but not males) reaching the attractant source. However, when the time required for beetles of both sexes taken together to reach the attractant source was considered, verbenone of higher enantiomeric purity had a greater effect on beetle behavior. Solutions of 99.5% (S)-(–)- and 98.3% (R)-(+)-verbenone increased the time required for beetles to reach the attractive source when compared to 93.1% (S)-(–)-verbenone. When pooled across enantiomeric blends, increasing concentrations of verbenone resulted in slower responses in beetles that reached the attractant source within 2 min. Males and females did not respond to verbenone alone. 相似文献
70.
The effects of pre-oxidation of char from Taiheiyo coal, a non-caking bituminous coal, in the 400–550 °C temperature range on its gasification reactivity with N2-H2O at 0.1 MPa (steam partial pressure of 13.2 kPa) have been investigated. The pre-oxidation of char markedly enhances gasification rates at temperatures between 800 and 900 °C. Reactivity is found to parallel the burn-off level during preoxidation at low temperatures (400–430 °C), whereas at relatively high temperatures (480–550 °C), the burn-off level only affects the reactivity slightly. The amount of CO and CO2 evolved from the preoxidized char by heat treatment is proportional to the burn-off level at low temperatures (400–430 °C), being closely related to the enhancement of the gasification reactivity in steam. 相似文献