全文获取类型
收费全文 | 926篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 148篇 |
金属工艺 | 17篇 |
机械仪表 | 16篇 |
建筑科学 | 47篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 140篇 |
水利工程 | 3篇 |
无线电 | 82篇 |
一般工业技术 | 139篇 |
冶金工业 | 231篇 |
原子能技术 | 8篇 |
自动化技术 | 92篇 |
出版年
2022年 | 7篇 |
2021年 | 11篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 25篇 |
2011年 | 29篇 |
2010年 | 34篇 |
2009年 | 25篇 |
2008年 | 26篇 |
2007年 | 29篇 |
2006年 | 30篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 20篇 |
1998年 | 83篇 |
1997年 | 44篇 |
1996年 | 31篇 |
1995年 | 25篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 27篇 |
1974年 | 8篇 |
1971年 | 9篇 |
1970年 | 14篇 |
1969年 | 5篇 |
1966年 | 10篇 |
1960年 | 5篇 |
1959年 | 5篇 |
排序方式: 共有949条查询结果,搜索用时 15 毫秒
61.
Wang Y. Bartelt H. Ecke W. Moerl K. Lehmann H. Schroeder K. Willsch R. Kobelke J. Rothhardt M. Spittel R. Shan L. Brueckner S. Jin W. Tan X. Jin L. 《Photonics Technology Letters, IEEE》2010,22(3):164-166
62.
SA Kliewer JT Moore L Wade JL Staudinger MA Watson SA Jones DD McKee BB Oliver TM Willson RH Zetterstr?m T Perlmann JM Lehmann 《Canadian Metallurgical Quarterly》1998,92(1):73-82
PURPOSE: To determine the effects of 28 d of creatine supplementation during training on body composition, strength, sprint performance, and hematological profiles. METHODS: In a double-blind and randomized manner, 25 NCAA division IA football players were matched-paired and assigned to supplement their diet for 28 d during resistance/agility training (8 h x wk[-1]) with a Phosphagen HP (Experimental and Applied Sciences, Golden, CO) placebo (P) containing 99 g x d(-1) of glucose, 3 g x d(-1) of taurine, 1.1 g x d(-1) of disodium phosphate, and 1.2 g x d(-1) of potassium phosphate (P) or Phosphagen HP containing the P with 15.75 g x d(-1) of HPCE pure creatine monohydrate (HP). Before and after supplementation, fasting blood samples were obtained; total body weight, total body water, and body composition were determined; subjects performed a maximal repetition test on the isotonic bench press, squat, and power clean; and subjects performed a cycle ergometer sprint test (12 x 6-s sprints with 30-s rest recovery). RESULTS: Hematological parameters remained within normal clinical limits for active individuals with no side effects reported. Total body weight significantly increased (P < 0.05) in the HP group (P 0.85 +/- 2.2; HP 2.42 +/- 1.4 kg) while no differences were observed in the percentage of total body water. DEXA scanned body mass (P 0.77 +/- 1.8; HP 2.22 +/- 1.5 kg) and fat/bone-free mass (P 1.33 +/- 1.1; HP 2.43 +/- 1.4 kg) were significantly increased in the HP group. Gains in bench press lifting volume (P -5 +/- 134; HP 225 +/- 246 kg), the sum of bench press, squat, and power clean lifting volume (P 1,105 +/- 429; HP 1,558 +/- 645 kg), and total work performed during the first five 6-s sprints was significantly greater in the HP group. CONCLUSION: The addition of creatine to the glucose/taurine/electrolyte supplement promoted greater gains in fat/bone-free mass, isotonic lifting volume, and sprint performance during intense resistance/agility training. 相似文献
63.
介绍了中子照相技术的原理和基本装置,并将其应用于混凝土材料的检测和研究中.结果表明:中子照相能够直观地检测钢筋混凝土内部的裂缝发展情况,并能实现对混凝土中水分侵入过程的可视化研究.在成像数据的基础上,对传统的水分侵入模型进行了修正,认为在水分侵入的初始阶段,水渗透系数为常数;吸水超过4 h后,渗透系数则按指数函数衰减. 相似文献
64.
65.
66.
67.
LA Moore HT Broihier M Van Doren LB Lunsford R Lehmann 《Canadian Metallurgical Quarterly》1998,125(4):667-678
Gonadogenesis in the Drosophila embryo is a complex process involving numerous cellular migratory steps and cell-cell interactions. The mechanisms guiding germ cells to move through, recognize and adhere to specific cell types are poorly understood. In order to identify genes that are required for these processes, we have conducted an extensive mutagenesis of the third chromosome and screened for mutations disrupting germ cell migration at any point in embryonic development. Phenotypic analysis of these mutants demonstrates that germ cell migration can be broken down into discrete developmental steps, with each step requiring a specific set of genes. Many of these genes are involved in the development of gonadal mesoderm, the tissue that associates with germ cells to form the embryonic gonad. Moreover, mutations that we isolated affecting embryonic patterning as well as germ cell migration suggest that the origin of gonadal mesoderm lies within the eve domain of the developing mesoderm. 相似文献
68.
This study examines the impact of university spillovers on the locational choice of firm formation. Based on a unique and hand-collected data set of high-technology start-ups publicly listed in Germany, this paper tests the propositions that geographic proximity to the university is influenced by the kind of science and type of knowledge spillover. The results provide evidence that younger high technology start-ups (less than eight years old) settle near universities with a high academic output and a high number of students in both natural and social science. Thus, spillover of tacit knowledge has an impact on the firms' geographic decision. Older firms, however, only locate closer to technical universities in order to satisfy demand for traditional German industries such as engineering and machinery. 相似文献
69.
70.
JP Dubey DH Graham DS da Silva T Lehmann LM Bahia-Oliveira 《Canadian Metallurgical Quarterly》2003,89(4):851-853
Most isolates of Toxoplasma gondii can be grouped into 3 genetic lineages. In the present study, 67 isolates of T. gondii were obtained by bioassay in mice inoculated with brains and hearts of 96 asymptomatic chickens from an area highly endemic to human infection in Rio de Janeiro, Brazil. Of the 48 isolates genotyped using the SAG2 locus, 34 (70%) were of type I and 13 (27%) were of type III. No isolate of type II was recovered. Isolates from 1 chicken contained a type I and type III mixed infection, indicating natural multiparasite infection in the same animal. Cats fed mice infected with 11 type I strains shed 19-535 million oocysts in their feces, indicating that type I isolates can circulate in the environment. 相似文献