推荐回答（3个）
笔者因最近忙于写论文，在网上查阅了不少资料，也使用了不少查找论文的工具， 由于工作关系，长期跟搜索引擎打交道，所以也有了一些体会，在这里谈谈怎样用几大搜索引擎找论文和他们各自的特点。
注意，我这里讲的不是收费的数据库，长期查资料的人都知倒CNKI SD等论文数据库，一般在高校的朋友查这些会很方便，因为一般有点实力的学校都是会买这些资源，而像我这种不当学生很多年的人要想免费进这些数据库只能全网疯狂搜索高校代理和密码了。
实际上除了这些资源网络上还是有一些很不错的搜索方式可以查询到质量很高的论文全文。下面我谈谈我的办法是什么。
第一个是利用好google 的高级搜索，教育网中大部分的论文资源都是以文档的格式储存的，所以用Google的高级搜索可以很方便的查找到各种文档比如我要查询心理学中弗洛伊德相关的论文直接在google 搜索 弗洛伊德 filetype:pdf | filetype:doc |filetype:rtf 就可以了，使用这个表达式的含义是在pdf doc 或rtf文档中搜索包含弗洛伊德的文档。当然如果你对搜索结果还不满意，还可以继续缩小范围 把上面的表达式中加上site:.edu.cn 这样又加上了必须是教育网的这一条件，准确度大大提高了。如果是搜索国外文档别忘了再加上filetype:ps
Ps文档在国内并不流行可在国外却非常常见而且不少ps文档里面都是全文。很多人喜欢用google的学术搜索: http://scholar.google.com 但实际用过发现还不如在google中使用高级搜索语句来得准确。Google学术搜索中有很多是打不开全文
当然如果嫌google太麻烦,还可以试试alseek 学术搜索http://www.alseek.com 或http://www.alseek.cn ,从某种意义上里说alseek是google的翻版，但它却大大简化了google的搜索过程，使用分类的tab可以很快找到搜索的文档类型，从结果上看准确度也还不错，搜索中文用alseek.cn搜索英文用alseek.com都能得到不少全文文档。我在前期几乎都是用google的不过后来逐渐偏向使用alseek了，特别是alseek中文站，因为我要的资料中不光有文档，这一点上alseek的方向性比google要强一些，毕竟是专门的论文搜索引擎，几乎所有关键字的结果都跟学术相关。
如果是英文资料还有两个不得不说的站点 http://www.findarticles.com 和http://www.essaypride.com 专业性上这两个不如前面两个，但如果是找一般的评论性文章，绝对是好用的，这两个网站中的文章在google中是搜不到的。
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