全文获取类型
收费全文 | 721篇 |
免费 | 50篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 8篇 |
综合类 | 2篇 |
化学工业 | 202篇 |
金属工艺 | 13篇 |
机械仪表 | 25篇 |
建筑科学 | 15篇 |
能源动力 | 45篇 |
轻工业 | 83篇 |
石油天然气 | 3篇 |
无线电 | 67篇 |
一般工业技术 | 162篇 |
冶金工业 | 26篇 |
原子能技术 | 9篇 |
自动化技术 | 119篇 |
出版年
2024年 | 4篇 |
2023年 | 22篇 |
2022年 | 71篇 |
2021年 | 88篇 |
2020年 | 44篇 |
2019年 | 38篇 |
2018年 | 50篇 |
2017年 | 40篇 |
2016年 | 51篇 |
2015年 | 22篇 |
2014年 | 31篇 |
2013年 | 48篇 |
2012年 | 28篇 |
2011年 | 45篇 |
2010年 | 33篇 |
2009年 | 27篇 |
2008年 | 27篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有779条查询结果,搜索用时 15 毫秒
121.
In Mozambique, domestic energy is often composed of a mix of sources, primarily used for lighting and cooking, with biomass and kerosene as more common sources. Electrification programs, intended to connect new consumers countrywide, have not significantly contributed either to the intensification of electricity consumption or to the reduction of the use of biomass in households. The choice of energy source is dependent on price and on the capability of the household to invest in energy-consuming appliances. Based on the data from a household survey carried out in Mozambique during 2002/03, this paper analyzes the geographic differences in unit expenditures for domestic energy and finds evidence of an inverted energy ladder with prices of useful energy units. The data show that biomass sources are often more expensive per unit of useful energy than higher-grade sources, supporting arguments favoring electrification as a poverty alleviation strategy. In addition, this study estimates the likelihood of poor households transitioning from biomass to electricity consumption based on various factors. Results indicate that income is not a determining factor in the transition, but wealth and the level of the Primary Energy Consumption Share (PECS) are as important factors as the nature of the energy mix. 相似文献
122.
This study assessed 1500 adolescents from the National Longitudinal Study of Youth to test the hypothesis that African American mothers differentially socialize their girls and boys. The results showed that later-born boys had fewer chores, argued more with their mothers, lived in less cognitively stimulating homes, and were not allowed to make the same decisions as were the girls or firstborn boys at the same age. The later-born boys were also lowest in achievement and highest in externalizing behaviors. Parenting differences accounted for the achievement differences but not for the externalizing behavior differences. It was concluded that the later-born boys would achieve at the same rates as their siblings if they were socialized in the same manner as their siblings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
123.
An improved method of DNA preparation for PCR‐based detection of Brucella in raw camel milk samples from Riyadh region and its comparison with immunological methods
下载免费PDF全文
![点击此处可从《Journal of Food Safety》网站下载免费的PDF全文](/ch/ext_images/free.gif)
124.
125.
Javed Alam Ufana Riaz S. M. Ashraf Sharif Ahmad 《Journal of Coatings Technology and Research》2008,5(1):123-128
The application of nanotechnology in the corrosion protection of metals has recently gained momentum. A polymer nanocomposite
coating can effectively combine the benefits of organic polymers, such as elasticity and water resistance, to that of advanced
inorganic materials, such as hardness and permeability. Environmental impact can also be improved by utilizing nanostructure
particulates in coatings and eliminating the requirement of toxic solvents. Nanocomposites have also proven to be an effective
alternative to phosphate-chromate pretreatment of metallic substrate, which is hazardous due to the presence of toxic hexavalent
chromium. This article reports some of the preliminary investigations on the corrosion-resistance performance of soya oil
alkyd, containing polyaniline/ferrite nanocomposite. The corrosion-protective performance was evaluated in terms of physico-mechanical
properties, corrosion rate, and SEM studies. The polyaniline/ferrite nanocomposite coatings were found to show a far superior
corrosion-resistance performance compared to that of a pure PANI/alkyd system. 相似文献
126.
Retinol binding protein 4 (RBP4) is a useful biomarker in the diagnosis of type 2 diabetes since its level in the serum is higher in insulin-resistant states. Accurate measurement of the serum RBP4 levels is hampered by conventional immunologic methods, such as enzyme-linked immunosorbent assay (ELISA). In this study, therefore, we have developed an aptamer-based surface plasmon resonance (SPR) biosensor that can be used to sense for RBP4 in serum samples. A single-stranded DNA (ssDNA) aptamer that showed high affinity (Kd = 0.2 +/- 0.03 microM) and specificity to RBP4 was selected. This RBP4-specific aptamer was immobilized on a gold chip and used in a label-free RBP4 detection using SPR. Analysis of RBP4 in artificial serum using SPR was compared with ELISA and Western blot analysis. Our results indicated that the RBP4-specific aptamer-based SPR biosensor gave better dose-dependent responses and was more sensitive than ELISA assays. As such, this RBP4 aptamer-based SPR biosensor can be potentially used to monitor the RBP4 levels within the serum as an indicator of type 2 diabetes. 相似文献
127.
This study traces the rhythms of news storytelling on Twitter via the #egypt hashtag. Using computational discourse analysis, we examine news values and the form of news exhibited in #egypt from January 25 to February 25, 2011, pre‐ and post‐resignation of Hosni Mubarak. Results point to a hybridity of old and newer news values, with emphasis on the drama of instantaneity, the crowdsourcing of elites, solidarity, and ambience. The resulting stream of news combines news, opinion, and emotion to the point where discerning one from the other is difficult and doing so misses the point. We offer a theory of affective news to explain the distinctive character of content produced by networked publics in times of political crisis. 相似文献
128.
129.
130.
The fluid loss control performance of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS®)‐based copolymers added to cement slurries was studied at 27 and 100°C, respectively. It was found that effectiveness of these fluid loss additives solely relies on achievement of a high adsorbed amount on the surface of cement. At elevated temperature (100°C), CaAMPS®‐N,N‐dimethyl acrylamide copolymer (CaAMPS®‐co‐NNDMA) exhibits reduced adsorption and hence decreased fluid loss control of the cement slurry. The reason behind this behavior is poor calcium binding capability of the sulfonate anchor groups, which coordinate with calcium atoms present on the mineral surface. Whereas, an increase in the sulfate concentration present in cement pore solution instigates partial coiling of CaAMPS®‐co‐NNDMA and causes only a slight influence on the performance of this copolymer. The elevated sulfate content results from thermal degradation of ettringite, a cement hydrate mineral produced during the early stages of cement hydration. Incorporation of minor amounts (~ 1.3 mol %) of maleic anhydride into this copolymer produces a terpolymer, which exhibits higher and more stable adsorption, even at high temperature. This effect is owed to the presence of homopolymer blocks of polycarboxylates distributed along the polymer trunk. On mineral surfaces, they present much stronger anchor groups than sulfonate functionalities, as evidenced by their higher calcium binding capability. Consequently, fluid loss performance of CaAMPS®‐co‐NNDMA‐co‐MA is little affected by temperature. Understanding the influence of temperature on the physicochemical interactions occurring between additives and the mineral surface can help to design more effective admixtures suitable for high temperature applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献