全文获取类型
收费全文 | 340篇 |
免费 | 17篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 133篇 |
金属工艺 | 2篇 |
机械仪表 | 3篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 97篇 |
水利工程 | 1篇 |
无线电 | 16篇 |
一般工业技术 | 38篇 |
冶金工业 | 8篇 |
自动化技术 | 37篇 |
出版年
2023年 | 7篇 |
2022年 | 30篇 |
2021年 | 42篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 23篇 |
2012年 | 20篇 |
2011年 | 27篇 |
2010年 | 19篇 |
2009年 | 12篇 |
2008年 | 18篇 |
2007年 | 15篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有359条查询结果,搜索用时 0 毫秒
31.
Mkaouar Hana Zalila Bechir Hugues Jérôme Jmaiel Mohamed 《International Journal on Software Tools for Technology Transfer (STTT)》2020,22(2):219-247
International Journal on Software Tools for Technology Transfer - Formal methods have become a recommended practice in safety-critical software engineering. To be formally verified, a system should... 相似文献
32.
One of the most important issues in a liquid propellant rocket is to measure the amount of remaining liquid propellant under low gravity environment during space mission. This paper presents the results of experiment and analysis of a pressure–volume–temperature (PVT) method which is a gauging method for low gravity environment. The experiment is conducted using 7.4 l tank for liquid nitrogen with various liquid-fill levels. To maximize the accuracy of a PVT method with minimum hardware, the technique of a helium injection with low mass flow rate is applied to maintain stable temperature profile in the ullage volume. The PVT analysis considering both pressurant and cryogen as a binary mixture is suggested. At high liquid-fill levels of 72–80%, the accuracy from the conventional PVT analysis is within 4.6%. At low fill levels of 27–30%, the gauging error is within 3.4% by mixture analysis of a PVT method with specific low mass flow rate of a helium injection. It is concluded that the proper mass flow rate of a helium injection and PVT analyses are crucial to enhance the accuracy of the PVT method with regard to various liquid-fill levels. 相似文献
33.
The acid-catalyzed decomposition of unusually stable 1-(2,1-benzisothiazol-3-yl)-3-phenyltriazenes in either aqueous perchloric acid or an aqueous mixture of perchloric and acetic acid was studied under pseudo-first order reaction conditions at 25 °C. Different products were obtained according to substitution on nitrogen N-3. For a triazene carrying hydrogen, the corresponding 3-amino-2,1-benzisothiazole and benzenediazonium salts were formed whereas in the case of substitution by an alkyl group (methyl and n-butyl) the 2,1-benzisothiazole-3-diazonium salt and N-alkylaniline were obtained. The observed rate constant (kobs) of the acid-catalyzed decomposition increased, initially, nonlinearly with increasing concentration of acid. Subsequently, kobs decreased slightly and at high acid concentration, increased steeply once again. An A-SE2 mechanism in which protonation of the triazene nitrogen proceeds simultaneously with cleavage of the N–N bond is proposed. Tautomerism of 1-(2,1-benzisothiazol-3-yl)-3-phenyltriazene was investigated using 1H NMR spectroscopy. 相似文献
34.
Hana Ross 《Nicotine & tobacco research》2004,6(1):181-189
This critique analyzes the methodology used in a study of the economic burden imposed on public finances in the Czech Republic by the consumption of cigarettes. The study was prepared by a consulting firm on behalf of the Phillip Morris Company. This critique, by using economic theory and a cost-benefit methodology, refutes the conclusion of the Phillip Morris study that smoking represents an economic benefit to Czech state finances. In fact, the correction of only one among numerous errors in assumptions and calculations in the Phillip Morris study leads to the opposite conclusion: Instead of savings of $150 million per year, smoking drains at least $373 million from the state budget annually, nearly.8% of the Czech gross domestic product. The net loss to the society is even greater if all pertinent costs and benefits are calculated properly. The critique demonstrates how to craft a rigorous economic response to common industry attempts to influence public opinion in which the industry employs specious or erroneous assumptions and data. 相似文献
35.
Transport of L -leucine into Schizosaccharomyces pombe cells from the stationary phase of growth (after preincubation for 60 min with 1% glucose) proceeds uphill, practically unidirectionally, and is mediated by at least two systems: a high-affinity system with a KT of 0·045 mmol 1?1 and Jmax of 3·3 nmol min?1 (mg dry weight)?1 and a low-affinity system with a KT of 1·25 mmol 1?1 and Jmax of 16·0 nmol min?1 (mg dry weight)?1. The high-affinity system has a pH optimum at 3.2, the accumulation ratio is highest at a cell density of 2–4 mg dry weight per ml and decreases with increasing leucine concentration. Transport of leucine by the high-affinity system is strongly inhibited by proton conductors, ammonium ions and by most amino acids, but only L -phenylalanine, L -isoleucine, L -valine and L -cysteine behave as fully competitive inhibitors. Systems of L -leucine transport in S. pombe are not constitutive. Transport activity appears only after preincubation of cells with a suitable source of energy. If cycloheximide is added during preincubation with glucose, no transport systems for leucine are synthesized. After removal of glucose, the activity of transport systems decays with a half-time of about 20 min. The presence of cyclic AMP increases the initial rate of leucine uptake only in cells preincubated with glucose and in the absence of cycloheximide. 相似文献
36.
37.
Salwan K. J. Al-Ani Raid A. Ismail Hana F. A. Al-Ta’ay 《Journal of Materials Science: Materials in Electronics》2006,17(10):819-824
Optoelectronic properties of CdS:In/Si anisotype heterojunction photodetector fabricated by depositing of polycrystalline
CdS and indium doped CdS films used thermal resistive technique on clean monocrystalline p-type silicon substrates are presented. The effect of In diffusion
temperature(T
d)in CdS layer on the optoelectronic characteristics of these devices has been studied. Two peaks situated at 650 and 800 nm
with values of 0.32 and 0.43 A/W, respectively, were observed in the responsivity plot. Other optoelectronics properties such
as detectivity, photovoltaic, and response time are also presented. 相似文献
38.
Nataša Pipenbaher Peter Lange Moeller Jan Dolinšek Mogens Jakobsen Hana Weingartl Avrelija Cencič 《International Dairy Journal》2009,19(3):166-171
Nitric oxide (NO) affects multiple gastrointestinal functions, including mucosal inflammation and antimicrobial activity. The aim of this study was to screen the ability of probiotic bacteria to stimulate NO production in porcine intestinal epithelial cells and macrophages in the presence and absence of interferon gamma (INF-γ). Production of NO in intestinal epithelium was stimulated by individual strains of lactobacilli without INF-γ priming. While none of the tested bifidobacteria were capable of inducing NO production, most constitutively secreted NO. Most tested strains induced a significant increase in NO production compared with the control cells in the macrophage cell line 3D4/21. Results support the protective role of the individual strains of the genera Lactobacillus and Bifidobacterium and may lead to new approaches for manipulating and regulating immune responses at the mucosal surfaces of the gastrointestinal tract. 相似文献
39.
Hydrolysis of the epoxide groups of the copolymer glycidylmethacrylate - ethylenedi-methacrylate in variously concentrated sulphuric acid solutions was studied. An approximate activation energy of hydrolysis, 41 kJ mol?1, was determined from the temperature dependences. For the sake of comparison the effect of pH on the degree of hydrolysis over the whole range of pH values was examined, and the importance of the results with respect to other reactions of the copolymer used was discussed. 相似文献
40.
Polymeric composites were prepared by reticulate doping of poly(γ-methyl-L-glutamate) (PMLGA) and poly(γ-methyl-LD-glutamate) (PMLDGA, 1 : 1) having different conformation forms with 1,3-dimethylimidazolium-TCNQ complex salt. The heat induced α-helix to coil transition in PMLGA and α-helix to β-form and coil transition in PMLDGA were carried out in chlorobenzene and o-dichlorobenzene at temperatures between 70 and 150°C. The conductivity of polyglutamate composites thermally treated and prepared at 70°C is higher by approximately two orders of magnitude than that of thermally not treated films cast at ambient temperature. The conductivity of the most conductive reticulate-doped PMLGA film is higher by more than four orders of magnitude than that of the 1,3-dimethylimidazolium-TCNQ complex salt in pressed pellets. 相似文献