全文获取类型
收费全文 | 1712篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 100篇 |
金属工艺 | 7篇 |
机械仪表 | 1篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 8篇 |
轻工业 | 27篇 |
水利工程 | 6篇 |
石油天然气 | 11篇 |
无线电 | 30篇 |
一般工业技术 | 22篇 |
冶金工业 | 1451篇 |
原子能技术 | 4篇 |
自动化技术 | 37篇 |
出版年
2014年 | 8篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 18篇 |
2007年 | 9篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 54篇 |
1998年 | 410篇 |
1997年 | 231篇 |
1996年 | 150篇 |
1995年 | 84篇 |
1994年 | 80篇 |
1993年 | 81篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1990年 | 21篇 |
1989年 | 27篇 |
1988年 | 34篇 |
1987年 | 35篇 |
1986年 | 22篇 |
1985年 | 17篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 22篇 |
1979年 | 6篇 |
1978年 | 13篇 |
1977年 | 27篇 |
1976年 | 106篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1967年 | 3篇 |
1966年 | 10篇 |
1965年 | 13篇 |
1964年 | 7篇 |
1963年 | 11篇 |
1962年 | 11篇 |
1961年 | 12篇 |
1960年 | 11篇 |
排序方式: 共有1717条查询结果,搜索用时 31 毫秒
21.
22.
CE Alpers CC Tsai KL Hudkins Y Cui L Kuller RE Benveniste JM Ward WR Morton 《Canadian Metallurgical Quarterly》1997,13(5):413-424
Focal and segmental glomerulosclerosis (FSG) with endothelial tubuloreticular inclusions (TRIs) is the typical lesion of human HIV-associated glomerulopathy. Autopsy studies showed the presence of FSG in 3 of 15 macaques dying 15-120 weeks after experimental infection with a simian immunodeficiency virus (SIVMne). Ultrastructural studies generally revealed numerous endothelial TRIs (also present in normals), mesangial expansion, and evidence of mesangial cell injury. One additional animal had a small-vessel polyarteritis with a proliferative and focally crescentic glomerulonephritis; seven animals had mild, multifocal interstitial nephritis. All animals had documented viremia after infection; 14 of 15 developed antibodies to SIV postinoculation. Additional postmortem findings included severe enterocolitis, encephalitis, and opportunistic infections. In contrast, autopsy studies of macaques infected with a type D simian retrovirus (SAIDS-D/Washington, SRV-2) for similar periods of time (n = 40) showed no evidence of FSG. One SRV-infected animal had a mild proliferative glomerulonephritis. These studies indicate SIV-infected primates may provide a relevant model for study of human HIV-associated nephropathy. They also indicate the variable pathology that can be seen in primate infections of distinct retrovirus types, each of which produces a simian immunodeficiency state that resembles human AIDS. 相似文献
23.
24.
The shear bond strengths of the XR-Bonding System used in conjunction with Herculite composite, to the dentine of forty extracted human permanent first and second molars were determined after the test specimens were stored in physiological saline at 37 degrees C for 48 hours, one week, two weeks and four weeks, respectively. A shear load was applied to the base of the bonded composite cylinders with a knife-edged rod at a crosshead speed of 0.5 mm/minute. The shear bond strengths were expressed in megapascals (MPa). The quantitative microleakage of Class V preparations in dentine (cementum) in forty-eight extracted human maxillary permanent canines restored with the same dentinal bonding system and after storage in physiological saline at 37 degrees C for the same time intervals as for the shear bond strength tests, was determined. On the final day of each time interval the teeth were thermocycled X 500 in a 2 per cent methylene blue solution between 8 degrees C and 50 degrees C with a dwell time of 15 seconds. Microleakage was determined by a spectrophotometric dye-recovery method and expressed in microgram dye/restoration. There was a significant trend for the shear bond strengths to increase with duration of storage (p = 0.01) but the quantitative microleakage was not significantly different (p = 0.75). 相似文献
25.
Detecting Deception in Children: Event Familiarity Affects Criterion-Based Content Analysis Ratings.
26.
In a study of how aviation expertise influences age differences in narrative processing, young and older pilots and nonpilots read and recalled aviation and general narratives. They chose referents for sentences referring to a protagonist or minor character mentioned 1 sentence (recent character) or 3 sentences (distant character) before this target sentence. All groups chose referents less accurately for sentences about distant and minor characters than about recent and protagonist characters, perhaps because these referents were less likely to be in working memory. Young readers and pilots were more accurate for distant and minor character target sentences in aviation narratives and recalled aviation narratives more accurately. Expertise did not reduce age differences. Expertise differences may reflect decreased demands on working memory capacity, and age declines may reflect reduced capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
28.
Tindall C.E. Martin J.P. Morrow D.J. Calvert P.A.J. 《Energy Conversion, IEEE Transaction on》1996,11(3):539-546
The use of small alternators, other than for standby purposes, is increasing and this has focused attention on the reliability and utility of the parameters normally quoted for such machines. Test procedures are described and methods used for parameter estimation discussed, with particular emphasis on the difficulties presented by small brushless machines 相似文献
29.
30.