全文获取类型
收费全文 | 14034篇 |
免费 | 186篇 |
国内免费 | 8篇 |
专业分类
教育 | 10253篇 |
科学研究 | 1213篇 |
各国文化 | 80篇 |
体育 | 1112篇 |
综合类 | 7篇 |
文化理论 | 88篇 |
信息传播 | 1475篇 |
出版年
2021年 | 104篇 |
2020年 | 155篇 |
2019年 | 254篇 |
2018年 | 353篇 |
2017年 | 362篇 |
2016年 | 330篇 |
2015年 | 202篇 |
2014年 | 281篇 |
2013年 | 2604篇 |
2012年 | 299篇 |
2011年 | 364篇 |
2010年 | 223篇 |
2009年 | 217篇 |
2008年 | 323篇 |
2007年 | 234篇 |
2006年 | 304篇 |
2005年 | 199篇 |
2004年 | 184篇 |
2003年 | 174篇 |
2002年 | 215篇 |
2001年 | 320篇 |
2000年 | 287篇 |
1999年 | 261篇 |
1998年 | 130篇 |
1997年 | 156篇 |
1996年 | 171篇 |
1995年 | 175篇 |
1994年 | 140篇 |
1993年 | 163篇 |
1992年 | 234篇 |
1991年 | 210篇 |
1990年 | 210篇 |
1989年 | 242篇 |
1988年 | 246篇 |
1987年 | 205篇 |
1986年 | 204篇 |
1985年 | 216篇 |
1984年 | 190篇 |
1983年 | 230篇 |
1982年 | 171篇 |
1981年 | 159篇 |
1980年 | 156篇 |
1979年 | 230篇 |
1978年 | 181篇 |
1977年 | 165篇 |
1976年 | 150篇 |
1975年 | 128篇 |
1974年 | 119篇 |
1973年 | 126篇 |
1971年 | 107篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
lintroductionMOrpnologicalandnlediantiltersasaclassofnonlineardiscretetilters11avegotWideapplicationsinsignalandimageprocessing.Incontrastwithlinearfilters,medianfiltersandtheirgenerationsareattractivebecausetheyareeasytoimplenlentandcansuppressimpulsenoi… 相似文献
152.
153.
Conversion efficiency of soft X-ray from 0.35 μm pulse laser-irradiated aluminium planar target at laser intensities 1013–1015 W/cm2 on the Xingguang-II facility (laser energy 5–90 J, focal spot ⊃ Ф 200 μm full width of half maximun (FWHM) 400–800 ps) was measured. A simple model was given to explain soft X-ray conversion
efficiency. In this model, because of the heat conduction from the laser-heated spot, the conversion was very small at lower
irradiance limit, while at higher limit it was bounded by the energy lost in blow off plasma. Consequently, at the laser intensity
around 2×1014 W/cm2, the X-ray conversion efficiency reaches a maximum.
Project suppoted by Shanghai Leading Academic Discipline Foundation (Grant No. T0104), and Science Foundation of Shanghai
Municipal Commission of Education (Grant No. 214680) 相似文献
154.
William D. Eiserman Lenore Shisler Terry Foust Jan Buhrmann Randi Winston Karl R. White 《Early childhood research quarterly》2007
This study assessed the feasibility of doing hearing screening in Migrant, American Indian and Early Head Start programs using otoacoustic emissions (OAE) technology. Staff members were trained to screen 0–3-year-old children for hearing loss using hand-held OAE equipment and a multi-step screening and referral protocol. Of the 3486 children screened as a part of the study, 77% passed an OAE screening at the first step, 18% more passed an OAE screening at the second step, and 5% were ultimately referred for medical or audiological follow-up. Eighty children were identified as having a hearing loss or disorder of the outer, middle or inner ear requiring treatment. Of these 80, six had permanent bilateral or unilateral hearing loss. Although the protocol suggested that the multi-step screening procedure should be completed within a 4-week time period or less, analysis of the data showed that for children requiring more than an initial OAE screening, the length of time over which the screening was completed ranged from 7 to 12 weeks. The median time required to complete a single OAE screening session was 4 minutes per child. The results demonstrate that OAE screening of young children using this protocol is practical and effective. The implications for conducting periodic hearing screening throughout early childhood are discussed. 相似文献
155.
156.
157.
158.
159.
Identification of Alcohol by Smell among Preschoolers: Evidence for Early Socialization about Drugs Occurring in the Home 总被引:1,自引:0,他引:1
This study tested preschoolers' ability to provide accurate verbal associations to alcoholic beverage odors and whether this ability was related to parental drinking patterns and motivations. Older preschoolers performed better than younger preschoolers; photographic cues improved performance; children who correctly identified a substance by smell had socially appropriate knowledge of the culturally appropriate users of the substance; children reported liking substances that are used mainly by children and adults, and generally reported disliking substances whose use is legally limited to adults only; children were better at identifying substances they commonly use, but success at recognition of alcoholic beverages was related to heavier parental drinking and use of alcohol for escape reasons. Findings have implications for theories of socialization to drug use and for models of prevention. 相似文献
160.