全文获取类型
收费全文 | 3506篇 |
免费 | 78篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 44篇 |
综合类 | 6篇 |
化学工业 | 609篇 |
金属工艺 | 97篇 |
机械仪表 | 49篇 |
建筑科学 | 140篇 |
矿业工程 | 11篇 |
能源动力 | 84篇 |
轻工业 | 308篇 |
水利工程 | 34篇 |
石油天然气 | 4篇 |
无线电 | 279篇 |
一般工业技术 | 461篇 |
冶金工业 | 1047篇 |
原子能技术 | 30篇 |
自动化技术 | 384篇 |
出版年
2021年 | 55篇 |
2020年 | 32篇 |
2019年 | 44篇 |
2018年 | 59篇 |
2017年 | 57篇 |
2016年 | 66篇 |
2015年 | 37篇 |
2014年 | 61篇 |
2013年 | 160篇 |
2012年 | 94篇 |
2011年 | 151篇 |
2010年 | 120篇 |
2009年 | 94篇 |
2008年 | 125篇 |
2007年 | 141篇 |
2006年 | 107篇 |
2005年 | 88篇 |
2004年 | 86篇 |
2003年 | 74篇 |
2002年 | 81篇 |
2001年 | 72篇 |
2000年 | 55篇 |
1999年 | 54篇 |
1998年 | 207篇 |
1997年 | 134篇 |
1996年 | 102篇 |
1995年 | 89篇 |
1994年 | 78篇 |
1993年 | 75篇 |
1992年 | 44篇 |
1991年 | 34篇 |
1990年 | 43篇 |
1989年 | 42篇 |
1988年 | 48篇 |
1987年 | 57篇 |
1986年 | 38篇 |
1985年 | 55篇 |
1984年 | 39篇 |
1983年 | 48篇 |
1982年 | 44篇 |
1981年 | 29篇 |
1980年 | 32篇 |
1979年 | 36篇 |
1978年 | 31篇 |
1977年 | 35篇 |
1976年 | 44篇 |
1975年 | 57篇 |
1974年 | 27篇 |
1973年 | 27篇 |
1972年 | 23篇 |
排序方式: 共有3587条查询结果,搜索用时 15 毫秒
11.
Mazzocco Michèle M. M.; Freund Lisa S.; Baumgardner Thomas L.; Forman Lisa; Reiss Allan L. 《Canadian Metallurgical Quarterly》1995,9(4):470
An extensive evaluation was conducted with 16-yr-old monozygotic twins concordant for the fragile X full mutation but discordant for mental retardation. The clearly affected twin had an IQ score of 47; 77% of her neuropsychological z scores were at least 2 SDs below average. Her sister had an IQ score of 105 and average neuropsychological performance. However, each girl demonstrated relative verbal strengths and visual-spatial weaknesses. Their parents rated each girl as having significant problems with attention, conduct, anxiety-withdrawal, and hyperactivity. The girls did not rate themselves as having significant anxiety. These findings are consistent with group data on females with fragile X and demonstrate the wide range of effects associated with the fragile X full mutation. This case report implicates the importance of a psychosocial phenotype of fragile X independent of cognitive ability level. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
13.
Button Cathryn M.; Grant Malcolm J.; Hannah T. Edward; Ross Abraham S. 《Canadian Metallurgical Quarterly》1993,25(2):230
Two studies identified and labeled the dimensions that people use to judge others' attitudes. In the 1st study, 50 male and 50 female undergraduates viewed pairs of attitude statements drawn from 1 or 2 large sets. For each pair of statements, Ss judged whether or not a person who agreed with one statement in the pair would be likely to agree with the other. The dimensions of liberalism and traditional values were found to underlie perceived attitudes. Validity was confirmed in a 2nd study with 60 male and 60 female undergraduates who rated the characteristics of hypothetical people who agreed strongly with particular statements. Results suggest that there is a common structure to people's perceptions of others' attitudes. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
George Grant Fiona Greer Norma H. McKenzie Arpad Pusztai 《Journal of the science of food and agriculture》1985,36(5):409-414
In a series of 10-day pair feeding experiments it was found that the nutritional value of diets containing beans was essentially the same for rats aged between 30 and 123 days. Thus net protein utilisation (NPU) values of 25–39 on diets containing Processor bean (35 g protein kg?1) + egg albumin (65g protein kg?1) were obtained. As food intakes were considerably reduced when rats were fed diets containing more than 35g protein kg?1 of Processor bean, the measurement of protein utilisation became increasingly more difficult. The severe disruption of the brush borders of duodenal and jejunal enterocytes, originally observed when bean-containing diets were fed to young (30-day-old) rats was also found with rats up to the age of 120 days on similar diets. Similarly, the development of circulating anti-lectin antibodies in the animals showed no age dependence within the age limits investigated. It was also shown that oral immunisation did not protect the rats from the effects of toxicity and that the immune response was a result of continuous absorption of lectin throughout the feeding period. Thus the extent and the mechanism of toxicity of Phaseolus vulgaris bean lectins were found not to be dependent on the age or maturity of the animal. 相似文献
15.
16.
17.
18.
JC Allan M Velasquez-Tohom C Fletes R Torres-Alvarez G Lopez-Virula P Yurrita H Soto de Alfaro A Rivera J Garcia-Noval 《Canadian Metallurgical Quarterly》1997,91(5):595-598
Mass treatment of the human population with niclosamide was carried out in 2 villages in rural Guatemala where Taenia solium was endemic, to determine how this would affect the epidemiology of the parasite. Intestinal taeniasis was diagnosed by microscopy and coproantigen testing, and porcine cysticercosis by a specific Western blot. Before mass treatment, the prevalence of human taeniasis was 3.5%; 10 months after treatment it was 1%, a significant decrease (P < 10(-4)). All tapeworms that could be identified to the species level were T. solium. Similarly, the seroprevalence of antibodies to cysticercosis in pigs declined from 55% before treatment to 7% 10 months after treatment, once again a significant decrease (P < 10(-6)). These effects were seen in both villages. The possible use of mass chemotherapy as a tool in the control of T. solium is discussed. 相似文献
19.
20.
KJ Clark AB Sarr PG Grant TD Phillips GN Woode 《Canadian Metallurgical Quarterly》1998,63(2-4):137-146
Rotaviruses are the leading cause and coronaviruses are the major contributors of acute gastroenteritis in the young of various mammalian and avian species. Despite numerous trials and decades of research, vaccines have limited efficacy particularly for calves. As an alternative method of controlling infection, we have investigated broad spectrum antiviral agents that are not discriminatory among various viruses. This report involves testing a variety of adsorbent agents including charcoal, clay, and clay minerals to adsorb rotavirus and coronavirus in vitro. Results revealed that all the adsorbent agents had good to excellent capability of adsorbing rotavirus and excellent capability of adsorbing coronavirus. Percent adsorptions ranged from 78.74% to 99.89% for rotavirus and 99.99% for coronavirus; while sand (negative control) was < 0.01%. A high affinity binding was present as determined by a low percent desorption (0.06-3.09%). However, the adsorbent bound virus complex retained, and may have actually enhanced, infectivity. 相似文献