全文获取类型
收费全文 | 1172篇 |
免费 | 27篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 72篇 |
综合类 | 4篇 |
化学工业 | 371篇 |
金属工艺 | 47篇 |
机械仪表 | 22篇 |
建筑科学 | 23篇 |
能源动力 | 53篇 |
轻工业 | 79篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 63篇 |
一般工业技术 | 264篇 |
冶金工业 | 90篇 |
原子能技术 | 39篇 |
自动化技术 | 76篇 |
出版年
2023年 | 8篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 61篇 |
2012年 | 29篇 |
2011年 | 66篇 |
2010年 | 46篇 |
2009年 | 55篇 |
2008年 | 67篇 |
2007年 | 45篇 |
2006年 | 52篇 |
2005年 | 52篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 31篇 |
2001年 | 22篇 |
2000年 | 27篇 |
1999年 | 27篇 |
1998年 | 52篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 27篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 17篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 21篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 19篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 29篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 19篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有1209条查询结果,搜索用时 406 毫秒
211.
Kinetic parameters for the anodic oxidation of hypochlorite ion have been determined by means of normal pulse voltammetry by using a platinum disk as the working electrode. By using the working electrode that formed an oxide film by electrochemical pretreatment, the effect of the lattice oxygen of the surface oxide on the reaction was also examined. The measurement results were analyzed by the classical method, and then the analytical results were evaluated by digital simulation. The normal pulse voltammogram of the hypochlorite ion showed quasi-reversible oxidation waves. The apparent rate constant was calculated to be 5.0-8.1 × 10−4 cm s−1, depending on the electrode surface state. At the low-concentration range of <4.0 mg Cl dm−3, the oxidation current was concentration dependent at the cathodically polarized electrode, while it became independent after the anodic polarization. 相似文献
212.
The electrooxidation of methanol, ethanol, and 2-propanol was investigated with interdigitated array electrodes (IDAEs). The IDAE oxidizes alcohol at the generator and reduces the reaction intermediates produced by the oxidation process at the collector. Thus, the reaction intermediates can be estimated with the IDAE. The IDAE in the present work was made of sputter deposited Pt and Pt–Ru. The use of Ru free and added electrodes provides information on the effect of Ru addition on the alcohol oxidation. Cyclic voltammetric analyses revealed that Ru addition enhances the oxidation currents and reduces the Eonset of the alcohols. The detectable reaction intermediate at the methanol and ethanol oxidation was proton, while the intermediate species was acetone in 2-propnaol oxidation. 相似文献
213.
Kubota K Sato Y Suzuki Y Goto-Inoue N Toda T Suzuki M Hisanaga S Suzuki A Endo T 《Analytical chemistry》2008,80(10):3693-3698
Glycopeptides prepared from 1 nmol of a mixture of glycoproteins, transferrin, and ribonuclease B by lysylendopeptidase digestion were isolated by lectin and cellulose column chromatographies, and then they were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and MALDI-quadrupole ion trap (QIT)-TOF mass spectrometry which enables the performance of MS ( n ) analysis. The lectin affinity preparation of glycopeptides with Sambucus nigra agglutinin and concanavalin A provides the glycan structure outlines for the sialyl linkage and the core structure of N-glycans. Such structural estimation was confirmed by MALDI-TOF MS and MALDI-QIT-TOF MS/MS. Amino acid sequences and location of glycosylation sites were determined by MALDI-QIT-TOF MS/MS/MS. Taken together, the combination of lectin column chromatography, MALDI-TOF MS, and MALDI-QIT-TOF MS ( n ) provides an easy way for the structural estimation of glycans and the rapid analysis of glycoproteomics. 相似文献
214.
Beverley M. Dancy Dr. Nicholas T. Crump Daniel J. Peterson Dr. Chandrani Mukherjee Dr. Erin M. Bowers Dr. Young‐Hoon Ahn Dr. Minoru Yoshida Dr. Jin Zhang Dr. Louis C. Mahadevan Dr. David J. Meyers Dr. Jef D. Boeke Dr. Philip A. Cole 《Chembiochem : a European journal of chemical biology》2012,13(14):1973-1973
215.
216.
Hano T Oshima Y Kinoshita M Tanaka M Mishima N Ohyama T Yanagawa T Wakamatsu Y Ozato K Honjo T 《Environmental science & technology》2007,41(4):1473-1479
This study investigates the adverse and persistent effects of ethinylestradiol (EE2) on mature gonads of transgenic olvas-GFPIST II-YI medaka (Oryzias latipes). The measurement of gonadal size calculating the GFP-fluorescent area was used as a technique that enabled monitoring gonads in living specimens by GFP fluorescence. First, mature medaka were exposed to EE2 (47.8-522 ng/L) for 4 weeks. The gonads showed a significant reduction of the GFP-fluorescent area and Gonadosomatic Index in males exposed to EE2 at >216 ng/L and females exposed at 522 ng/L. Histologically, males at all treatments exhibited testis-ova and additionally, high connective tissue prevalence at > or =216 ng/L. Next, mature male medaka were exposed to EE2 (43.7-473 ng/L) for 3 weeks and allowed to depurate for 6 weeks, to investigate persistent effects of EE2. Continuous gonad observation showed that GFP began to decline 3 weeks after initial exposure to > or =215 ng/L. After depuration, the gonad's fluorescent areas gradually recovered, with no statistical difference at the end of the depuration period; normal spermatogenesis was present in these individuals. Alterations in GFP fluorescence clearly indicate the condition of the gonad in transgenic medaka and this strain showed a facilitated screening fish model to detect the adverse effects on the gonad by estrogenic chemicals. 相似文献
217.
Yukiko Hara‐Kudo Akiko Yamasaki Miho Sasaki Tsutomu Okubo Yuji Minai Minoru Haga Kazuo Kondo Yoshiko Sugita‐Konishi 《Journal of the science of food and agriculture》2005,85(14):2354-2361
Antibacterial effects of catechins, the major green tea polyphenols, were studied using Clostridium and Bacillus spores. Incubation with crude catechins decreased the number of C botulinum and C butyricum spores but not B cereus spores. Furthermore, the effects of six catechin derivatives on spores were investigated. (−)‐Epicatechin gallate (ECg), (−)‐epigallocatechin (EGC), (−)‐epigallocatechin gallate (EGCg) and (+)‐gallocatechin gallate (GCg) were more effective in decreasing C botulinum and C butyricum spore numbers than (+)‐catechin (C) and (−)‐epicatechin (EC). The vegetative growth of C botulinum and B cereus was inhibited by crude extracts of the catechins. Specifically, purified GCg and EGCg inhibited the vegetative growth of C botulinum and B cereus. The inhibitory effect of ECg on B cereus was similar to that of GCg. However, toxin‐production by B cereus was not inhibited by catechin. Damage to the membrane of C butyricum spores by catechin derivatives was shown using fluorescent microscopy. This study shows that low concentrations of catechins, although requiring a long exposure time, inhibited the growth of bacterial spores. However, the effects of the purified derivatives of the catechins were not the same and GCg and EGCg were found to be the most potent. Spores that are generally resistant to many disinfectants were sensitive to catechins. Copyright © 2005 Society of Chemical Industry 相似文献
218.
Lead-bismuth eutectic (LBE) is a candidate coolant for fast reactors. Its physical, chemical and neutronic properties make it a prospect coolant for the reactors. However, corrosion of structure is the main problem of utilizing LBE as a coolant. Compatibility of welded structure with LBE at high temperature should be considered clearly for feasibility of lead-bismuth-cooled fast reactors. This study was preformed to investigate the mechanical properties and corrosion characteristics of the welded ferritic-martensitic (FM) steel, HCM12A, in LBE at 650 °C for 500 h. The welding methods were TIG welding (137 mm/min; 480 W), YAG laser welding (780 mm/min; 287 W) and electron beam welding (1000 mm/min; 60 kW). The oxygen concentration of test environment was maintained at 7 x 10−7 wt% by injecting Ar-H2-steam gas mixture. Vickers hardness test and SEM/EDX analysis were conducted on the cross section of welded HCM12A. It was found that oxide layer was larger in the weld zones than base metal (BM). However, outer layer was detached on some areas. 相似文献
219.
A corrosion test was conducted to investigate the corrosion characteristics of SiC and Si3N4 in a flowing lead-bismuth eutectic (Pb-Bi) with a fluid temperature of 550 °C, a velocity of 1 m/s, and an oxygen concentration of 1 × 10−6 wt% for an exposure time of 2000 h. The weight losses of the SiC and Si3N4 specimens were lower than those of corrosion-resistant steels tested under the same condition. The specimens showed excellent resistance against an element dissolution and an oxidation in the Pb-Bi flow. The surface was slightly damaged due to some stresses of the Pb-Bi flow and/or those generated by adhered Pb-Bi in the test procedure. 相似文献
220.
Jorge Minoru Hashimoto Elizabeth Harumi Nabeshima Helio Spinelli Cintra lvaro Renato Guerra Dias Fernando Martínez Bustos Yoon Kil Chang 《Journal of the science of food and agriculture》2002,82(8):924-930
Extrusion‐cooked blends of cassava starch (CS) and wheat gluten (WG) were studied. The data were analysed using response surface methodology. The results showed the formation of new structures characterised by lower radial expansion (RE) and specific volume (SV) when gluten was added to CS. WG content was the most important variable affecting RE, water absorption index (WAI), water solubility index (WSI), SV and difference in colour (ΔE) of the extruded products, but feed moisture content and barrel temperature also influenced RE. WAI was affected by a significant interaction between WG content and barrel temperature. The extruded products had lower WAI values and higher WSI values than WG‐free products. Heat, high shear rate and high pressure during extrusion cooking caused mechanical destruction or denaturation of the WG and gelatinisation and dextrinisation of the starch components. The extruded blends could have diverse applications. © 2002 Society of Chemical Industry 相似文献