用“毕业达人”,亲测很好用,下文献神器
1、知网有免费入口,可以自已找下。网上免费账号也有不少。2、去论坛活动活动。3、如果文章不多,可以在这里求助。我们来帮你下载即可。4、如果是国外的,需要看不同的数据库再回答你。
你可以上草根论文网看看,那边的论文都是免费的,当然也包括参考文献。具体的你可以上去看看。
推荐到OA图书馆,可免费下载全文。输入英文关键词即可。
1、知网有免费入口,可以自已找下。网上免费账号也有不少。2、去论坛活动活动。3、如果文章不多,可以在这里求助。我们来帮你下载即可。4、如果是国外的,需要看不同的数据库再回答你。
其实不论是中国知网还是万方,包括维普都可以搜索并下载外文文献,不过都是需要付费的。
SCI-HUB--- 堪称是“谁人不知,无人不晓”的下载神器,在我们下载外文文献时提供了极好的便利,但因某个原因,SCI-HUB要经常更改域名,会经常出现链接被封。国家哲学社会科学文献中心--- 由国家免费向公众提供的学术资源。文献免费下载,缺点:收录的文献资源有限,有时候会找不到需要的文献。中国知网 ---中国知网可以说是中国知识资源总库,提供了各行各业中外文的数据资源,中文文献部分文章可以免费下,外文文献基本没有下载权限Library Genesis电子书下载 ---是一个电子书免费下载平台,提供科技、科学文章等优质的电子书。Library Genesis和SCI-HUB可谓是难兄难弟,因为版权问题,有时文献会下载不了或者页面显示无法连接。seek68文献馆---稳定运行十来年,收录了海量的中外文数据库资源,涉及到各个学科。并且简单易操作,对写论文查询下载文献有很大的帮助。
iData是由北京大学、清华大学、浙江大学、复旦大学等师生学者共同筹建的用于教学、科研目的的公益互联网项目。号称知网镜像网站。国家哲学社会科学文献中心是由国家免费向公众提供的学术资源。seek68文献馆中外文数据库汇总,免费试用中外文献下载。ZLibrary是一个免费电子书。ABC Chemistry是化学方面的免费全文网上期刊数据库。‘Open Access Library(OALib)图书馆免费下载学术文献和论文。sci-hub通过文献DOI检索免费下载外文文献。有时不稳定。HighWire 斯坦福学术文献电子期刊提供免费全文的学术文献出版商。FindaRticles是一个强大的能够获取免费出版文献的搜索引擎。该网站通过HighBeam Research数据库提供免费和付费内容。Science美国的一个科学网站,是大型综合性、多学科、核心期刊引文索引数据库,免费!
个人所知,目前比较好用的几个免费论文及其他文献网站有这几个:国家哲学社会科学文献中心。该网站所有资料免费浏览及下载,但仅局限于哲学及社会科学相关文献。爱论文网站。这是一个提供多种论文免费下载的网站。
知网吗?一般校园网可以下,自己下就要钱
知网、万方的论文资料能免费下载?万万没想到用这个软件就能搞定
不知道,随便给你一个疏水缔合型聚合物P(AMTA)溶液性质的研究疏水缔合型水溶性聚合物是指在聚合物亲水性大分子链上带有少量疏水基团的一类水溶性聚合物。在聚合物水溶液中,疏水基团之间由于憎水作用而发生聚集,使大分子链产生分子内和分子间缔合。在临界缔合质量分数以上,形成分子间缔合为主的超分子结构,增大了流体力学体积,故具有较好的增黏性。在盐溶液中,由于小分子电解质的加入增加了溶液极性,使疏水缔合作用增强,表现出明显的抗盐性质。 疏水缔合型水溶性高分子很难合成,且不易表征,把疏水部分连接到水溶性聚合物链上,一般采用胶束共聚合或者使用具有表面活性的大单体进行共聚,胶束聚合需要在体系中加入大量的表面活性剂,这就增加了后处理过程的复杂性。利用表面大单体共聚合,需要事先合成大单体,这方面的技术也有相当大的难度。作者采用丙烯酸十四酯作为疏水单体,直接用沉淀聚合法制备疏水缔合型聚合物P(AM/TA)共聚物,从而使共聚反应及其产物的后处理过程较为简单易行。并用凯达尔定氮法表征共聚物的组成,研究共聚物的溶液性能和对苯丙乳液的增稠性。 1实验 1.1试剂 丙烯酰胺(AM),质量分数不少于985%,根据文献提供的方法提纯;N,N-甲基甲酰胺(DMF),分析纯;甲醇、氯化钠,化学纯;丙烯酸十四酯(TA),实验室自制;苯丙乳液由福建省福州树脂有限公司提供。 1.2P(AM/TA)共聚物的合成 称取一定量的AM和TA单体,用DMF溶解,转入三颈瓶中,通氮除氧。升温至80℃,加入引发剂反应4h,过滤,产物用甲醇洗涤多次,以除去未反应的单体。40℃真空干燥至恒重。 1.3分析测试 凯达尔定氮法测定共聚物的组成。用乌氏黏度计测定共聚物溶液特性黏度[η],测试温度为(30±O1)℃。聚合物溶液表观黏度用NDJ-I型旋转黏度计测定。 2结果与讨论 2.1共聚物稀溶液性质不同疏水基团摩尔分数的P(AM/TA)共聚物在蒸馏水和w(NaCl)=5%的溶液中的特性黏度[η]值列于表1。 聚合物的[η]正比于溶液中大分子线团的流体力学体积,因而能反应大分子线团收敛、卷曲的程度。从表1可知,随共聚物的TA链节摩尔分数的增加,其水溶液的[η]值逐渐减小,在w(NaCl)=5%的溶液中也是持续减小。这是因为在稀溶液中,疏水基团缔合以分子内缔合为主,随着TA摩尔分数的增加,分子内缔合增强,导致分子链卷曲。在盐溶液中,由于离子电荷的作用,使疏水链节分子内缔合力增强,分子链收缩,因而[η]值也持续下降。 2.2疏水基团TA摩尔分数对聚合物溶液黏度的影响 图1和图2分别表示P(AM/TA)系列共聚物及PAM在蒸馏水和w(NaCl)=5%的溶液中表观黏度与聚合物质量分数的关系曲线。PAM溶液黏度随其质量分数的增加而平缓上升,而疏水共聚物溶液的质量分数为3O%~4O%时其黏度急剧增加,表明疏水基团聚集而导致分子间缔合,形成了物理交联网络。此时共聚物溶液的质量分数即是临界缔合的质量分数。如图1所示,随TA摩尔分数增加,共聚物溶液的黏度显著增加。当疏水基团摩尔分数较高时,其溶液黏度随质量分数增加的速度更快,共聚物的临界缔合质量分数降低。如图2所示,加入Nacl溶液后,溶液表观黏度有较大提高,如质量分数为O%的P(AM/TA)-1 5聚合物溶液在20℃,转速为6r/min时,黏度达OmPs,而在水溶液中的黏度只有374mPa·s。不同TA摩尔分数的聚合物的质量分数均较其在纯水中低。Hydrophobically associating polymer P (AMTA) the nature of the study solution Hydrophobically associating water-soluble polymer is the hydrophilic polymer with a small amount of macromolecular chain hydrophobic group of a class of water-soluble Aqueous solution in the polymer, the hydrophobic groups and between the role as a result of hydrophobic aggregation occurred, so that large molecules have a molecular chain and inter-molecular Associating the critical mass fraction of the above, the formation of intermolecular association based supramolecular structure, increases the volume of fluid mechanics, it has good by In salt solution, because of the addition of small molecule electrolyte solution increased polarity, so that co-operation with enhanced hydrophobic association, shows that the nature of the Hydrophobically associating water-soluble polymer-based synthesis is difficult and not easily characterized, in part to hydrophobic chains connected to the water-soluble polymer, the general use of micellar copolymerization, or the use of the large surfactant monomer to copolymerization, polymer micelles need in the system by adding a large number of surface-active agent, which, after an increase of the complexity of the The use of the surface monomer copolymerization, the need for prior synthesis of large monomer, this technology also has considerable Author tetradecyl acrylate used as a hydrophobic monomer, the direct use of precipitation polymerization Preparation of hydrophobically associating polymer P (AM / TA) copolymers, so that the product of copolymerization and post-processing is more simple and easy And characterization of nitrogen determination Kedar copolymer composition, study the solution properties of copolymers of styrene-acrylic emulsion and of the 1 Experimental 1 Reagents Acrylamide (AM), the mass fraction of not less than 985 percent, according to documents provided by purification methods; N, N-dimethylformamide (DMF),分析纯; methanol, sodium chloride, chemical pure; acrylic 10 four acetate (TA), laboratory-made; styrene-acrylic emulsion resin from Fuzhou in Fujian Province L 2P (AM / TA) Copolymer Check that a certain amount of monomer AM and TA, using DMF dissolved into three-neck bottle, pass oxygen Warming to 80 ℃, reaction by adding initiator 4h, filtering, washing the product several times with methanol to remove unreacted 40 ℃ vacuum drying to constant 3 Analysis and Testing Determination of nitrogen Kedar will be the composition of Determination of intrinsic viscosity with copolymer solution viscosity [η], the test temperature (30 ± O1) ℃ Apparent viscosity of polymer solution with NDJ-I-type rotary viscometer 2 Results and Discussion 1 Dilute Solution Properties of Copolymers of different mole fraction of hydrophobic groups of the P (AM / TA) copolymers in distilled water, and w (NaCl) = 5% of the solution intrinsic viscosity [η] values listed in Table Polymer [η] is proportional to the solution of the fluid dynamics of macromolecular coil volume, which can respond to the convergence coil macromolecules, the degree of We can see from Table 1, with the copolymer chain of the TA increase in mole fraction, the aqueous solution of [η] value decreases in w (NaCl) = 5% of the solution is continued to This is because in dilute solution, the hydrophobic group to intramolecular association based association, with the mole fraction of the increase in TA, to enhance intramolecular association, resulting in the molecular chain In salt solution, because of the role of ionic charge, so that intramolecular hydrophobic chain to enter into force enhancement, molecular chain contraction, so [η] value continued to TA hydrophobic group 2 mole fraction of polymer solution viscosity on the impact of figures 1 and 2, respectively, P (AM / TA) series of copolymers and PAM in distilled water, and w (NaCl) = 5% in the apparent viscosity of the solution and the relationship between the mass fraction of polymer PAM solution viscosity with the increase of mass fraction of gentle rise, and the hydrophobic copolymer solution for the mass fraction of 3O% ~ 4O%, when a sharp increase in viscosity, indicating that aggregation of hydrophobic groups and lead to intermolecular association, forming a physical crosslinking网络 At this point the mass fraction of copolymer solution that is the critical mass fraction of the As shown in Figure 1, with the mole fraction of TA increased, the viscosity of copolymer solution increased When the mole fraction of hydrophobic groups is high, the solution viscosity increases with the mass fraction of the faster, the critical aggregation copolymer mass fraction As shown in Figure 2, by adding Nacl solution, the solution has greatly enhanced apparent viscosity, such as the mass fraction of O% for the P (AM / TA) -1 5 polymer solution at 20 ℃, rotation speed 6r/min , the viscosity of OmPs, and viscosity in aqueous solution only 374mPa TA different mole fraction of the mass fraction of polymer in water were
百度 谷粉学术 (谷歌学术替代品)功能和谷歌一样,然后利用附带sci-hub功能下载论文里面也有知网、万方、维普等免费共享账号望采纳
用“毕业达人”,亲测很好用,下文献神器
1、知网有免费入口,可以自已找下。网上免费账号也有不少。2、去论坛活动活动。3、如果文章不多,可以在这里求助。我们来帮你下载即可。4、如果是国外的,需要看不同的数据库再回答你。
您可以进入爱学术网站,先输入自己要搜索内容的关键词,然后在搜索结果页面选择sci类型即可。
Sci-hub在我们获取文献与学术论文的道路上提供了极大的便利。一款可与之媲美的网站——Library Genesis可以替代网站Sci-hub;Library Genesis 网站设计简洁,连颜色都跟 Sci-hub 差不多,而且此网站号称是帮助全人类知识无版权传播的计划,实际上也确实如此,它做到了。
网页链接这个网址里面有免费账号可以在英文数据库Web of Science检索,在这个网址下载
首先可以到ei和sci检索的数据库下载。其他的可以到中国知网,aps,sciencedirect之类的下载,而且一般在学校,图书馆之类的网站下载是免费的吧。