本期内容主要介绍下Results & Discussion写作中的一个基本原则:先摆现象,讨论完了才能给出结论。什么意思呢?在SCI论文写作时,一般采用分总式,即先将实验结果列出来,然后结合文献等进行讨论,最后得出结论。结论的得出要基于实验结果和讨论。说起来好像全世界人民都知道一样,但是实际写作中还是会有一些这样或那样的问题,下面举一些例子:

先摆现象,讨论完了才能给出结论

参考文献:Liu, J. et al. Catal. Commun. 2017, 99, 6-9.

1. 通过XRD谱图来说明Pt纳米颗粒很分散:

不恰当的写法:XRD patterns suggest that Pt nanoparticles are well dispersed on TiO2 support.

正确的写法:No obvious characteristic diffraction peaks of Pt are detected, presumably due to the small crystalline size and good dispersion of Pt0, which is also confirmed by TEM images.

不恰当写法的分析:XRD谱图能够直接说明Pt的高分散么?这是个常识么?XRD怎么就说明了Pt的高分散了呢?

正确写法的分析:1) 实验结果:No obvious characteristic diffraction peaks of Pt are detected;2) 推论:presumably due to the small crystalline size and good dispersion of Pt0; 3) 佐证:which is also confirmed by TEM images。

不恰当的原因:没有讨论直接给出结果,让人摸不着头脑。对于熟悉相关知识点的读者来说,要理解你的结论问题可能不大,但是对于那些不了解相关知识的读者来说,理解起来就有一定困难了。从科技文写作的角度来讲,好的论文应该逻辑严密,每个结论的得出都有迹可循。除非是公理,否则不能直接给出结论,必须有一定的讨论。

2. 类似的,在STEM分析中,诸如line scanning profiles以及EDS mapping中说明纳米颗粒是合金(或者核壳)结构

参考文献:Zou, S. et al. J. Phys. Chem. C 2017, 121, 4343-4351.

不恰当的写法:EDX mapping images demonstrate a ZnO@Bi(NO3)3 core-shell structure for BN-ZnO catalyst.

正确的写法:EDX mapping images show enrichment of Zn signals in the core and homogeneous distribution of Bi signal in the shell. Meanwhile, line scanning exhibits a broad peak for Zn located at the center of the profile and two intensive peaks for Bi on both sides, further confirming the core-shell configuration.

不恰当的原因与例1相同,都是不加讨论直接给出结论。

3. 上面的两个例子都是不讨论直接给出结论,其实还有一种值得商榷的写法是先给出结论,然后再进行讨论,比如:

参考文献:Liu, J. et al. Catal. Sci. Technol. 2017, 7, 1203-1210.

值得商榷的写法:The coexistence of Pt and the partially reduced Bi2O3?x is essential to achieve high efficiency in alcohol oxidation (先给出了结论).Specifically, Pt/Bi2O3?x could catalyze the oxidation of BA to BAD, obtaining a conversion and selectivity up to 94.1 ± 2.7% and >99.9% within 5 h, respectively (sample # 06 in Table 2). However, no detectable activity was observed under the same reaction conditions for other catalysts including unsupported PtNPs, Bi2O3 and Pt/Bi2O3. The big difference between Pt/Bi2O3?x (sample # 06) and Bi2O3?x (sample # 04) reveals that the presence of Pt is critical for alcohol oxidation(讨论了Pt的重要作用). The complete inactivity of unsupported PtNPs (sample # 02) and Pt/Bi2O3 (sample # 05), on the other hand, demonstrated the pivotal role played by the Bi2O3?x phase(讨论了部分还原Bi2O3-x的作用).

更恰当的写法: Interestingly, it was found that Pt/Bi2O3?x could catalyze the oxidation of BA to BAD, obtaining a conversion and selectivity up to 94.1 ± 2.7% and >99.9% within 5 h, respectively (sample # 06 in Table 2). However, no detectable activity was observed under the same reaction conditions for other catalysts including unsupported PtNPs, Bi2O3 and Pt/Bi2O3(先摆出实验现象). The big difference between Pt/Bi2O3?x (sample # 06) and Bi2O3?x (sample # 04) reveals that the presence of Pt is critical for alcohol oxidation(讨论Pt的作用). The complete inactivity of unsupported PtNPs (sample # 02) and Pt/Bi2O3 (sample # 05), on the other hand, demonstrated the pivotal role played by the Bi2O3?x phase(讨论了部分还原Bi2O3-x的作用). It is important to point out that the initial TOF of 0.57% Pt/Bi2O3?x, even up to 21.24 h?1 for the first 5 h at room temperature, is 7 times higher than that reported for 1 wt% Pt/Ca(Mg)-ZSM catalysts, and twice than that reported for the Cu(II) coordination complex in homogeneous catalysis of BA oxidation(将Pt/Bi2O3-x的活性与文献进行对比). The extremely high activity of Pt/Bi2O3?x leads to a hypothesis that the coexistence of Pt and the partially reduced Bi2O3?x is essential to achieve high efficiency in alcohol oxidation(最后得出结论).

分析:上面两段话很多内容其实是完全一致的,主要的不同在于The coexistence of Pt and the partially reduced Bi2O3?x is essential to achieve high efficiency in alcohol oxidation这个结论摆在什么位置。从逻辑上来说,第二种写法先给出实验现象,然后针对现象进行讨论,最后结合文献对比得出实验结论是正常的逻辑,属于典型的分总式。而第一种写法先给出结论,然后再分别讨论,属于总分式,如果在这段末尾把结论换个形式再说一遍就属于总分总的形式。这里不推荐这两种格式,总分式的结论放在最前面,虽然很明确的告诉了读者这一段的核心思想是什么,但是从逻辑上来说,显得有点颠倒,因为科学研究多是探索型实验而不是验证型,是从实验现象中总结分析得出的结论。而总分总是在段落开头和结尾都有结论,有点重复,对于写作的人要求也很高,你至少要保证这两个地方的语句有一定的变化才不至于让人读起来显得乏味。

句与句之间的逻辑

撰写学术论文的目的是希望所发现或者发明的内容能够得到大家认可。因此,受到认可是学术论文最核心的一点。而要想说服别人,很重要的一点必须条理清楚,逻辑严密。事实上,任何一篇科学论文的内容都是片面的,只是反映了作者在当时当下所认知的程度,论文中可能还会存在这样或者那样的不足。而好的学术论文不是拼命地告诉别人我这个东西已经登峰造极,完美无缺了,而是用数据,用严密的逻辑告诉别人:从目前的研究结果,我们可以得出哪些结论,而这些结论对整个领域的发展有哪些重要启示。

那么逻辑结构体现在哪些地方呢?句与句之间,段与段之间!今天先介绍下句与句之间的逻辑关系,口说无凭,实例为证:

1. 选用逻辑关系

参考文献:G. J. Hutchings et al. Science, 2016, 351, 6276.

A limiting factor in achieving high selectivity toward H2O2 with Au-Pd/TiO2 catalysts prepared by the wet impregnation method is that the catalyst nanoparticles exhibit a variation in composition with particle size, with the smallest particles being Pd-rich (传统催化剂选择性的局限性). These small Pd-rich NPs are likely to be highly active for H2O2 synthesis and also for its subsequent hydrogenation and decomposition, as has been shown when AuPd catalysts are prepared by colloidal techniques with particle sizes typically 2 to 4 nm (限制选择性的原因). In the case of the Sn-Pd system, the small Pd-rich NPs are often associated with the amorphous SnOx films(本实验中的发现). We postulated that it might be possible to further decrease the H2O2 degradation activity of the catalyst by inducing encapsulation of the ultrasmall Pd-rich NPs by this SnOx film(基于已有理论和现有发现做出的推论). We therefore used subsequent thermal treatments in an attempt to induce a strong metal-support interaction (SMSI) between the Pd and SnOx layer (根据推论设计的实验方案). We first added a low-temperature reduction step (200°C, 2 hours, 5% H2 in Ar), which made the catalysts stable to multiple reaction cycles (实验操作). However, the H2O2 degradation activity increased markedly, from 65 mol kg-1 hour-1 to 300 mol kg-1 hour-1; this rate increase was associated with the reduction of Pd2+ to metallic Pd, as shown by XPS (实验结果). Metallic Pd is known to be a more effective H2O2 hydrogenation catalyst (对实验结果的进一步解释).

这一段一共有9句话,每句话所要表达的意思我都用红色字体进行了标注。1)首先介绍了传统催化剂Au-Pd/TiO2在选择性上的局限性;2)介绍了这种局限性的具体原因;3)本实验中的发现;4)基于已有理论和现有发现做出的推论;5)根据推论设计的实验方案;6)根据推论设计的实验方案;7)实验操作;8)实验结果;9)对实验结果的进一步解释。可以看得出来,作者在写作时层层递进,这是研究思路的内在逻辑。而为了更好地体现这种逻辑,作者在文字上也有所承接(请注意上面一段文字中蓝色字体标记的内容)。比如第一句话中引出了Pd rich这个概念,然后第二句话将Pd rich NPs的具体影响进行了进一步地解释(Pd rich NPs就是这种递进关系的衔接词)。而类似的,第三句话,作者还是通过Pd rich NPs从文献拉回本文的实验结果。第四句话中更是针对Pd rich NPs提出了推论。类似的第八句和第九句通过metallic Pd将两个句子衔接在一起,体现出了递进的关系。

温馨提示:并列结构是所有逻辑结构中最弱的,如果有递进关系,请用递进,如果有因果关系,请用因果关系!文字之间存在逻辑关系,读者读起来会觉得很顺畅,而相反如果文字之间没有逻辑关系,只是简单地罗列,则会显得很生涩,言之无味。

2. 使用连接词

另外一种更加简单地体现句与句之间的逻辑关系是使用连接词.下面简单列举一下一些基本的连接词:

表示递进的:then, subsequently, in addition, besides, what is more, moreover, furthermore, in order to...further, 等等;

表示转折和让步关系的:but, however, nevertheless, nonetheless, on the contrary, on the other hand, in contrast, instead of, even so, though, although, despite, regardless of, in spite of, as opposed to等等;

表示层次关系的:firstly, first of all, to begin with, secondly...finally, last but not least, afterwards,simultaneously, at the meantime, meanwhile, eventually等等;

表示因果关系的:because, because of this, since, for this reason, thanks to, due to, owing to, seeing that, on account of, therefore,as a result, hence, consequently, accordingly等等;

表示归纳总结的:in conclusion, in summary, in sum, in short,overall,等等;

表示条件关系的:unless, otherwise, only if, if only, suppose that, as soon as, in case that, providing that, given that等等。

这里依旧举一个简单的例子:

参考文献:Liu, J. and Fan, J. et al., Catal. Sci. Technol., 2014, 4, 441-446.

To further confirm the alloy structure, HRTEM and line-scanning analysis were employed. As shown in Fig. 1c, the lattice fringes of Pt1Pd3 display interplanar spacings of 0.223 and 0.192 nm in the particle, which match well respectively with those of the (111) and the (200) planes of the fcc PtPd alloy. On the other hand, the compositional line profiles of Pt and Pd cross an individual particle shown in Fig. 1d also suggest the NPs to be alloy with homogeneous distributions of elemental Pt/Pd. Moreover, as can be seen from Fig. 1a, the PtPd NPs are well dispersed in the m-SiO2 framework and the sizes of PtPd alloy NPs are rather small with a narrow size distribution (4.1 ± 0.6 nm). The mesoporous SiO2 framework is highly ordered, suggesting that the presence of PtPd NPs does not affect the mesoscopic structure of the oxide support. These results were also confirmed by SAXS data and N2 adsorption–desorption data. As shown in Fig. 2, the interplanar distance of the (100) plane calculated from the SAXS analysis are both 10 nm. Meanwhile, the results from N2 adsorption–desorption data confirm that both Pt1Pd3–m-SiO2 and m-SiO2 have characteristics that are typical of mesoporous materials, and they possess similar BET surface areas (422.8 m2 g?1vs. 439.4 m2 g?1), indicating that the introduction of PtPd has little influence on the structure of the MMOs.

这一段话是典型的对材料微观结构进行表征的结果的叙述,是R&D里面最常见的看图说话形式。而为了让这些表征手段关联起来,作者采用了很多连接词。这些连词的使用可以让句与句之间关联更加紧密,从而能够结合多种表征手段来综合说明材料的微观结构信息。

段与段之间的逻辑

实例一:

参考文献:Science, 2010, 328, 342-345. 来自埃默里大学Craig L.Hill课题组。熟悉OER领域,特别是分子OER催化剂(均相催化剂)领域的朋友应该对他不陌生,这篇论文算是他的成名作之一,论文第一次提出了Carbon-Free的全无机多金属氧酸盐(POM),解决了传统分子OER催化剂的不稳定性问题。

抛开论文内容本身来讲,论文写作的逻辑结构也很有参考价值,今天主要来分析论文下R&D中段与段之间的逻辑关系。

先列出最有代表性的原文内容:如何证明所合成的POM是稳定的?

论文第六段第一句:Aqueous cobalt ions and cobalt hydroxide/oxides that form in situ from the former are both known to be WOCs. Thus, we now describe seven lines of experimental evidence that 1 is a stable molecular WOC under turnover conditions and does not form either aqueous cobalt ions or cobalt hydroxide/oxide. (总述怎样来证实这个问题,本段后面的内容还包括两个证据)

论文第七段第一句:The third experimental probe of the stability of 1 involved selective catalyst poisoning experiments using 2,2′-bipyridine (bpy) as an inhibitor.(开门见山,告诉别人这一段是讨论第三个实验证据,与前一段的总述以及前两个证据有个承接关系)

论文第八段第一句:For our fourth probe of the stability of 1, we characterized the postreaction solution containing 1 by using 31P NMR despite the low solubility of 1 in the presence of excess [Ru(bpy)3]2+.(第四个实验证据)

论文第九段第一句:The fifth and sixth experimental probes of the stability of 1 involved IR characterization and reuse of the WOC after an initial catalytic run, which we carried out under conditions scaled up by a factor of 19 relative to run 1 in Table 2.(第五和第六个实验证据)

论文第十段第一句:The seventh argument for the stability of 1 during catalysis is voltammetric behavior demonstrating that catalytic activity of the active species is retained after turnover. (第七个实验证据)

论文第十一段第一句:Computational studies of the electronic structure of 1 provide additional support for the oxidative stability of the polytungstate ligands. (氧化稳定性)

分析:在R&D第一期内容的时候,我们曾经说过:对于一个段落而言,不建议使用总分式结构,而是推荐使用分总式结果,目的是:先摆现象,讨论完了才能给出结论。但是在段与段的逻辑关系中,会经常看到总分或者并列结构,比如本文就是先总述共采用了七种方法来证明稳定性,然后逐条证据进行分析。段与段之间所采用的是序数词的逻辑关系。同时,每一段的核心思想是统一的,都是为了证明稳定性(关键词:stability)。作者在每一段的第一句就很明确地指出这一段是干啥,且段与段之间紧密联系在一起,读者读起来会觉得很顺畅,而作者也很容易引导读者的思路,让其按照文章的逻辑进行思考。

当然,不可否认,并不是每篇论文都可以列出来1,2,3,4条,那么其它的论文是如何来实现段与段之间的逻辑关系呢?

实例二:

参考文献:Catal. Sci. Technol.,2014, 4,441–446 。出自浙大化学系范杰教授课题组,第一作者为刘娟娟博士。

R&D部分第一段第一句:X-Ray diffraction (XRD) measurements of the samples were carried out to determine whether the nanoparticles consisted of a mixture of nanoparticles or an alloy. (材料结构表征的核心:是否alloy)

R&D部分第二段第一句:To further confirm the alloy structure, HRTEM and line-scanning analysis were employed.(further confirm与第一段紧密联系起来)

R&D部分第三段第一句:The XPS analysis was carried out to study the surface components of PtPd metallic nanoparticles on m-SiO2.(体相讨论完了之后,表面结构分析,在上两段的基础上进一步分析)

R&D部分第四段第一句:The sol –gel approach exhibits excellent advantages in the regulation of the alloy composition. (在确定单一组成的结构之后,提出组成调控的概念,更进一步)

R&D部分第五段第一句:Since the relative amount of each constituent metal in the BMNPs could modify the electronic state of the primary catalytic component and tune the binding properties for intermediate species during the reaction, composition regulation could lead to optimized catalytic performance of BMNPs. (在指出组分调控之后,提出催化性能的优化,将结构与性能联系起来,再进一步,关键词composition regulation体现了与上一段的承接关系)

R&D部分第六段第一句:Besides regulation of the alloy composition, we also tuned the loading concentration of the Pt/Pd nanoparticles. (在讨论完组成调控之后,继续讨论负载浓度的影响。关键词alloy composition以及连接词besides都在逻辑关系的体现中有作用)

R&D部分第七段第一句:The approach is special as it not only regulates the composition of the alloy effectively, but it also facilities the control of the compositional parameter of the oxide supports.(前面都是讨论活性组分PdPt的结构性能,第七段通过这样的一句话转到了oxide support,连接词not only,but also 很关键,体现了与前面内容的逻辑关系)

R&D部分第八段第一句:Apart from this, we can also synthesize composite metal oxide supports by introducing another homogeneously distributed component, which may promote improved catalytic performance. (采用Apart from this进行连接,与上一段的逻辑关系就体现出来了)

总结:

好的论文能够在逻辑上引导读者按照你的行文思路进行思考,这样能够让读者从你的角度来理解你的研究。而严密的逻辑关系是让文章得到读者和审稿人认可的关键,这种逻辑关系在句与句之间,段与段之间都需要注意。Results & Discussion部分暂时先分享到这里。具体R&D里面各个部分如何写,请大家查看SCI论文写作实验室的“细说表征”模块,里面有很多表征手段描述的句型模板,希望能够帮助到大家!