全文获取类型
收费全文 | 591篇 |
免费 | 55篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 176篇 |
金属工艺 | 8篇 |
机械仪表 | 8篇 |
建筑科学 | 22篇 |
矿业工程 | 3篇 |
能源动力 | 14篇 |
轻工业 | 112篇 |
水利工程 | 6篇 |
无线电 | 42篇 |
一般工业技术 | 55篇 |
冶金工业 | 120篇 |
原子能技术 | 1篇 |
自动化技术 | 77篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 37篇 |
2020年 | 24篇 |
2019年 | 19篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 32篇 |
2015年 | 28篇 |
2014年 | 21篇 |
2013年 | 47篇 |
2012年 | 37篇 |
2011年 | 43篇 |
2010年 | 36篇 |
2009年 | 29篇 |
2008年 | 20篇 |
2007年 | 34篇 |
2006年 | 22篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有646条查询结果,搜索用时 140 毫秒
71.
Jan Brückner Sören Thieme Falko Böttger‐Hiller Ingolf Bauer Hannah Tamara Grossmann Patrick Strubel Holger Althues Stefan Spange Stefan Kaskel 《Advanced functional materials》2014,24(9):1284-1289
The lithium sulfur battery system has been studied since the late 1970s and has seen renewed interest in recent years. However, even after three decades of intensive research, prolonged cycling can only be achieved when a large excess of electrolyte and lithium is used. Here, for the first time, a balanced and stable lithium sulfur full cell is demonstrated with silicon–carbon as well as all‐carbon anodes. More than 1000 cycles, a specific capacity up to 1470 mAh g?1 sulfur (720 mAh g?1 cathode), and a high coulombic efficiency of over 99% even with a low amount of electrolyte are achieved. The alternative anodes do not suffer from electrolyte depletion, which is found to be the main cause of cell failure when using metallic lithium anodes. 相似文献
72.
73.
Alexander A. Khassin Vladimir V. Pelipenko Tatyana P. Minyukova Vladimir I. Zaikovskii Dmitrii I. Kochubey Tamara M. Yurieva 《Catalysis Today》2006,112(1-4):143-147
The catalytic activity of CuZn catalysts in the synthesis of methanol is related to those reduced Cu species, which originate from the CuxZn1−xO solid solution of wurtzite-like structure. Copper cations in the CuxZn1−xO solid solution are localized in the extended stacking faults of the ZnO lattice. Copper sites could be supposedly described as the product of introducing (OH)Cu(OH) to the planar defects of zinc oxide structure. Hydroxyl groups stabilize the planar defects of ZnO. The process of the samples reduction leads to the formation of flat Cu0 particles over the surface of zinc oxide. The planar defects of ZnO structure are preserved in the reduced state. During the reoxidation, copper atoms return back to the extended stacking faults of ZnO as the tape-like clusters of flat-square coordinated copper cations. 相似文献
74.
Halle Tamara G.; Kurtz-Costes Beth; Mahoney Joseph L. 《Canadian Metallurgical Quarterly》1997,89(3):527
The authors examined the achievement-related beliefs and behaviors of parents of economically disadvantaged African American youth, and the relations among parental factors and children's academic self-concept and achievement. Forty-one children and their primary caregivers were interviewed. Parents reported on their academic-related beliefs and behaviors. Children completed measures of academic self-concept and 2 standardized achievement tests: 1 during the summer and 1 at the end of the following school year. Significant and positive relations were found between parental belief and behavior measures within the domains of reading and math; however, parental beliefs were more strongly linked with child outcomes than were parents' achievement-oriented behaviors. The relation between parental beliefs and child outcomes was not mediated by children's academic self-concept. Results are discussed in light of models of family influences on achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
Wall Tamara L.; Shea Shoshana H.; Luczak Susan E.; Cook Travis A. R.; Carr Lucinda G. 《Canadian Metallurgical Quarterly》2005,114(3):456
Associations of alcohol dehydrogenase (ADH) gene polymorphisms (ADH1B*2 and ADH1C*1) with a lifetime alcohol use disorder (AUD) were examined in White college students. Alcohol-related endophenotypes likely to be influenced by elevations in acetaldehyde were also assessed. Individuals with an ADH1B*2 allele had lower rates of AUDs, consumed a lower maximum number of drinks in a 24-hr period, reported a greater level of response to alcohol, were more likely to have experienced alcohol-induced headaches following 1 or 2 drinks, and reported more severe hangovers than those lacking this allele. These findings are consistent with the hypothesis that enhanced sensitivity to alcohol and lower levels of alcohol use reflect the mechanism by which ADH1B*2 protects against developing an AUD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
A protein involved in the transport of glutathione has been identified, cloned and characterized from the fission yeast Schizosaccharomyces pombe. Database searches revealed the Sz. pombe ORF SPAC29B12.10c as a close homologue to several members of the OPT family, including the Saccharomyces cerevisiae high‐affinity glutathione transporter Hgt1p. The gene product of SPAC29B12.10c has been identified as a protein, named SpOPT1, localized within the plasma membrane, transporting the tripeptide glutathione. Disruption of SPAC29B12.10c led to strains inable to grow on media containing glutathione as a sole source of sulphur, due to the inability to internalize the tripeptide. Disruptants contained significantly less glutathione than wild‐type cells. Furthermore, ΔSpopt1 strains were non‐viable in a glutathione biosynthesis‐defective (Δgsh2) background. However, it was possible to complement the disruption of Spopt1 by overexpressing the intact ORF in the disrupted strain. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
77.
Carlos E. Bamberger Tamara J. Havedock Otto C. Kopp† 《Journal of the American Ceramic Society》1994,77(6):1659-1661
The ternary system SrO-CeO2 -TiO2 was investigated using X-ray diffractometry. The formation of a new compound, Sr2 Ce2 Ti5 O16 , was established, and its compatibilities with SrO, SrCeO3 , and SrTiO3 were studied. The results revealed the existence of a series of compounds Sr6–12x Ce6x Ti5 O16 and solid solutions Sr2+n Ce2 Ti5+n O16+3n ( n ≤ 6). 相似文献
78.
Concentration dependence of thermodynamic interaction parameters in a polymer-polymer-solvent system
Yury Lipatov Valentina Chornaya Anatoly Nesterov Tamara Todosiichuk 《Polymer Bulletin》1984,12(1):49-53
Summary The concentration dependence of Thermodynamic Interaction Parameters is reported for the system Polystyrene (PS, MW
3=4.4 · 105) — Polybutylmethacrylate (PBMA, MW
2=2.7 · 105) — CCl4. 相似文献
79.
Shara S. Shoup Tamara J. Haverlock Carlos E. Bamberger 《Journal of the American Ceramic Society》1995,78(5):1261-1264
A region of selected SrO-LnO1.5 -TiO2 (Ln = La, Ce, Pr, or Nd) systems was studied experimentally using X-ray diffractometry (XRD). A series of solid solutions with composition Sr4 x Ln2 x/ 3 Ti4 O12 having tetragonally distorted per-ovskite structures was found to exist along the tie line connecting SrTiO3 and Ln2 Ti3 O9 . Reactions of SrLn2 Ti4 O12 , representative compounds of the series, with SrO were also studied. Additionally, the solubility of TiO2 in Ln2 O3 -(3TiO2- m (Ln = La, Pr, or Nd) at 1300°C was investigated using XRD. 相似文献
80.
Reports on an experiment in which rats foraged in a 4-arm radial maze containing 4 feeders in each arm, with different percentages of baited feeders in each arm (0%, 25%, 50%, or 75%). The effects of three variables were examined: (1) Arm entrances were open or blocked to increase travel time between arms; (2) Feeders were uncovered or covered to decrease accessibility to food; (3) Food locations were randomly changed between sessions or remained fixed. Rats learned to discriminate between the 0% arm and arms containing food when food locations were fixed but not when food locations were random. Rats also learned the locations of baited feeders within arms with fixed food locations, but selectively visited baited feeders only if the feeders were covered. Comparisons of obtained data with computer simulations indicated that rats foraged near optimality. Patterns of foraging were best accounted for by a molecular maximizing model. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献