全文获取类型
收费全文 | 2621篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 39篇 |
金属工艺 | 13篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 5篇 |
轻工业 | 25篇 |
无线电 | 9篇 |
一般工业技术 | 63篇 |
冶金工业 | 2386篇 |
原子能技术 | 3篇 |
自动化技术 | 78篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 11篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 6篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 77篇 |
1998年 | 718篇 |
1997年 | 446篇 |
1996年 | 282篇 |
1995年 | 152篇 |
1994年 | 134篇 |
1993年 | 151篇 |
1992年 | 14篇 |
1991年 | 24篇 |
1990年 | 26篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 23篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 28篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 63篇 |
1976年 | 158篇 |
1975年 | 5篇 |
1964年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2632条查询结果,搜索用时 390 毫秒
11.
P Ferroni L Lenti F Martini F Ciatti GM Pontieri PP Gazzaniga 《Canadian Metallurgical Quarterly》1997,77(3):548-554
Gangliosides may play functional roles in platelet physiology, therefore this study has been designed to evaluate whether changes in ganglioside composition may occur as a consequence of platelet activation. The results obtained indicate that lactosylceramide and GM3 are the major glycosphingolipids of human platelets. The lipid-bound sialic acid (LBSA) content was 1.27 +/- 0.04 micrograms/mg of protein. Resting platelets did not express GD3; GD3 was synthesized upon platelet activation (24 +/- 8 ng/mg of protein). The stimulation of platelets with adenosine diphosphate showed the appearance of GD3 even in the absence of degranulation. Finally, incorporation of pyrene-labeled GM3 into platelet membranes, followed by stimulation with adenosine diphosphate, resulted in the appearance of a fluorescent band comigrating with GD3. The present studies indicate that sialytransferase activation may occur as an early event following platelet stimulation, leading to GD3 synthesis mainly from the GM3 pool. 相似文献
12.
13.
14.
The effect of caseinate and soy protein in the diet on the mutagenicity induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was assessed in-vivo and ex-vivo in the DNA-repair host-mediated assay and liquid suspension assay, respectively. Of the two proteins only casein showed a strong antimutagenic activity over the whole digestive tract, except in the stomach. It is suggested that the molecular structure of a protein determines its protective effect against mutagens: casein lacks secondary and tertiary structure so that amino acids are more readily available for interaction with the mutagen than with the amino acids in soy protein which is a globular protein. 相似文献
15.
16.
Lichen sclerosus is a chronic skin condition with a predilection for the genital area. In the present study, 35 male patients with lichen sclerosus were interviewed and examined. Blood screens were performed and histology was requested if not already performed. The findings indicate that lichen sclerosus in males exists as a spectrum of disease, ranging from a mild form with white plaques and few symptoms to a severe form with inflammation, atrophy and scarring with possible urological consequences. In many areas it differs from the condition in females; the association with autoimmune disease is weaker and there is less perianal and extragenital involvement. The association with malignancy in males is of lesser significance than initially believed. 相似文献
17.
18.
19.
An on-line, steam distillation/purge and trap gas chromatographic procedure is described for determination of halogenated analytes in foods and beverages. Recoveries were generally >80% (versus aqueous standards) from vegetable oil, flour, root beer, cream (10% butter fat), and milk spiked at 1-3 micrograms/kg for each of the 32 analytes studied. Analytes ranged in volatility from vinyl chloride to 1,2,3,4-tetrachlorobenzene. Repeatabilities from aqueous standards were <10% for most analytes. For a 1 g food sample, method detection limits ranged from 0.02 to 0.2 micrograms/kg for the 32 analytes. Reduced recoveries for less volatile analytes, however, occurred when steam-distillable, nonpolar food components were carried to the sparger. This effect was observed for citrus beverages containing steam-volatile limonene, roasted and ground coffees, and some salad dressings. The method was applied to a variety of foods. 相似文献
20.