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读者一般先看论文的标题，再读摘要，然后决定是否读全文。摘要写得好不好，对论文的受关注度影响很大。一篇论文的摘要就好像一篇微缩版的全文，用简练的语言来介绍你所做的这项研究，相当于一个故事的梗概。摘要通常分四个部分，各部分的详细程度根据刊物对字数的要求来调整：①用一两句话描写研究背景和科学问题，相当于简要的引言；②简单描写你做了什么样的实验，用了什么关键材料或方法，这部分相当于正文的材料与方法；③得到了哪些主要结果（不是结论），把最重要的、最核心的数据在摘要里呈现一下；④这个研究的核心结论和意义（可适度推广），通常用概括性和普适性的一两句话来表述。初学者容易忽视第①和④点，特别是对第④点的关注普遍不够。缺少了第④点会让审稿人觉得这项研究只有局限性的意义(local significance)，停留在就事论事上。摘要中第②和③点通常用一般过去时描述，而第①和④点用一般现在时。
结论和摘要很不一样，初学者往往在用词和表达上把两者混为一谈，重复表达，无法达到画龙点睛的目的。结论和摘要最大的不同是，结论是对整个研究结果的高度概括，不再描述具体的数据，将要点和亮点展现在读者面前。读者可能不一定理解你的全文，或没有兴趣读你的全文，但是看了这个结尾他知道了你研究的概貌。很多期刊在形式上也许没有单独的结论，但是文章结尾总有一个概括性的描述。所以，这个结论也可叫作“可以带回家的信息”(take-home message)。
下面我们用一些例子来展开讨论摘要写作的一些技巧。
For centuries ecologists have studied how the diversity and functional traits of plant and animal communities vary across biomes. In contrast , we have only just begun exploring similar questions for soil microbial communities despite soil microbes being the dominant engines of biogeochemical cycles and a major pool of living biomass in terrestrial ecosystems.
1.这两句话点明这项研究的背景和意义。
2.“for centuries”作为开头，非常容易吸引读者的眼球，当然作者在这样写的时候要把握一定的度。
3.第二句用“in contrast”开始，话锋一转，同样是引起读者兴趣的词。
We used metagenomic sequencing to compare the composition and functional attributes of 16 soil microbial communities collected from cold deserts, hot deserts, forests, grasslands, and tundra.
1.现在有不少刊物允许/鼓励使用第一人称，特别是一些高端的刊物，如 Nature 、 Science 和 PNAS 等。
2.明确本研究做了什么，用了什么材料——来自不同生态系统的土壤，采用了什么方法——对土壤微生物群落的宏基因组测序。
Those communities found in plant-free cold desert soils typically had the lowest levels of functional diversity (diversity of proteincoding gene categories) and the lowest levels of phylogenetic and taxonomic diversity.
“typically”这个词说明结果中还有些例外，但是作者抓住了主要矛盾，中国学生容易纠结一些细微的差别而忽视了大的趋势。
Across all soils, functional beta diversity was strongly correlated with taxonomic and phylogenetic beta diversity; the desert microbial communities were clearly distinct from the nondesert communities regardless of the metric used. The desert communities had higher relative abundances of genes associated with osmoregulation and dormancy, but lower relative abundances of genes associated with nutrient cycling and the catabolism of plant-derived organic compounds.
1.注意英文中分号的使用与中文不太一样。英文中，分号前后是两个内容紧密相关的独立句子，后面的句子是前面句子内容上的延伸。
2.“regardless of”这个短语在科技论文中也是十分常用的。
Antibiotic resistance genes were consistently threefold less abundant in the desert soils than in the nondesert soils, suggesting that abiotic conditions, not competitive interactions , are more important in shaping the desert microbial communities.
1.特别好的结构，突出“abiotic conditions”。
2.文章的要点和亮点被展现得淋漓尽致。
As the most comprehensive survey of soil taxonomic, phylogenetic, and functional diversity to date , this study demonstrates that metagenomic approaches can be used to build a predictive understanding of how microbial diversity and function vary across terrestrial biomes.
1.作者略有夸张，但这是撰写科技论文的气度，一篇论文总要在一个方面或一点上是最好的，哪怕是非常小的一点，这就是写论文的目的之一。
2.研究论证结果用一般现在时。
3.“predictive understanding”是本文，也是生态学的重要目标，即如何从现象描述上升到内在规律的揭示。
4.摘要的结尾都应该指出本项研究的意义，当然作者要把握这个度。太夸张的话，审稿人会不喜欢，有风险。
尽管摘要的基本内容大同小异，不同的刊物对摘要的要求（格式和字数等）不一样。有的刊物明确要求摘要分成四个部分，包括背景(Background)、方法(Methods)、结果(Results)和结论(Conclusions)，如 Environmental Health Perspectives 、 Plant and Soil 等。这种明确的要求有利于作者厘清思路，比较实际。
BACKGROUND: The inter-individual variation in metabolism of inorganic arsenic (iAs), involving methylation via one-carbon metabolism, has been well documented, but the reasons remain unclear .
“remain”作为一个情态动词在科技论文里经常出现。与“unclear”类似的还有“poorly characterized、poorly understood、largely unknown”等等。
OBJECTIVES: In this population-based study we aimed to elucidate the effect of nutrition on As methylation among women in Matlab, Bangladesh, where people are chronically exposed to iAs via drinking water.
1.注意这个一般过去时，表明在写这个论文前的动作，下面还会经常谈到，特别是在结果部分。
2.这里是现在时，表明是一个常态。
METHODS: We studied effects of macronutrient status using body mass index (BMI) among 442 women in early pregnancy (gestational week 8), and effects of micronutrient status (plasma folate, vitamin B 12 , zinc, ferritin, and selenium) among 753 women at gestational week 14. Arsenic metabolites in urine were measured by HPLC combined with hydride generation inductively coupled plasma mass spectrometry.
1.描述关键的材料与方法。
2.并列名词最后一个之前用“and”连接，但是对“and”之前是否加逗号，语法学家之间存有争议。
RESULTS: The median concentration of As in urine was 97 μg L -1 (range, 5-1, 216 μg L -1 , adjusted by specific gravity). The average proportions of iAs , monomethylarsonic acid, and dimethylarsinic acid in urine in gestational week 8 were 15%, 11%, and 74%, respectively .
1.复数，多种形态的砷。
2.“respectively”之前通常要用逗号。
Thus, the women had efficient As methylation in spite of being poorly nourished (one-third had BMIs <18.5 kg m -2 ) and having elevated As exposure, both of which are known to decrease As methylation.
1.这是科技论文常见的，类似的还有“despite、regardless of”，后面接名词或动名词。
2.“which”引导的从句在科技论文中特别常用，起到对主句的补充和扩展。
The metabolism of iAs was only marginally influenced by micronutrient status, probably because women, especially in pregnancy and with low folate intake, have an efficient betaine-mediated remethylation of homocysteine, which is essential for an efficient As methylation.
“marginally”这个词在科技英语中常用，想说明一个事或因子不是很重要，但又不想完全抛弃，是一种比较圆滑的表述。
CONCLUSIONS: In spite of the high As exposure and prevalent malnutrition, overall As methylation in women in early pregnancy was remarkably efficient. The As exposure level had the greatest impact on As methylation among the studied factors.
结论部分要对背景部分提出的问题加以回应。
Root-released carboxylates enhance the availability of manganese (Mn), which enters roots through transporters with low substrate specificity.
描述研究背景。
Leaf Mn concentration ([Mn]) has been proposed as a signature for phosphorus (P)-mobilising carboxylates in the rhizosphere.
提出假设。
Here we test whether leaf [Mn] provides a signature for root functional types related to P acquisition.
明确研究的目的。
Across 727 species at 66 sites in Australia and New Zealand, we measured leaf [Mn] as related to root functional type, while also considering soil and climate variables.
这句话给出研究区域、样地和物种数量，并指出对土壤和气候变量也加以考量。
To further assess the specific situations under which leaf [Mn] is a suitable proxy for rhizosphere carboxylate concentration, we studied leaf [Mn] along a strong gradient in water availability on one representative site. In addition, we focused on two systems where a species produced unexpected results.
还研究了几种特例。
Controlling for background site-specific variation in leaf [Mn] with soil pH and mean annual precipitation, we established that mycorrhizal species have significantly lower leaf [Mn] than non-mycorrhizal species with carboxylate-releasing root structures, e.g., cluster roots. In exception to the general tendency, leaf [Mn] did not provide information about root functional types under seasonally waterlogged conditions, which increase iron availability and thereby interfere with Mnuptake capacity. Two further exceptions were scrutinised, leading to the conclusion that they were ‘anomalous' in not functioning like typical species in their families, as expected according to the literature.
这部分先明确两种根的功能类型叶片Mn浓度存在显著差异，再指出例外的情形。
Leaf [Mn] variation provides considerable insights on differences in belowground functioning among co-occurring species. Using this approach, we concluded that, within typical mycorrhizal families, some species actually depend on a carboxylatereleasing P-mobilising strategy. Likewise, within families that are known to produce carboxylate-releasing cluster roots, some do not produce functional cluster roots when mature. An analysis of leaf [Mn] can alert us to such ‘anomalous' species.
呼应前面提出的假设，对叶片Mn浓度能否指示根系分泌羧酸作为活化土壤P的策略做一个总结。
有的刊物要求摘要分成四点或更少，但是对四点内容没有明确的约束。如果没有特殊要求，这四点通常应包括上面谈到的摘要基本要素：背景、实验、主要结果和结论/意义。比较典型的是植物科学领域的 New Phytologist 。
We investigated structural and functional diversity in arbuscular mycorrhizal (AM) symbioses involving three plant species and three AM fungi and measured contributions of the fungi to P uptake using compartmented pots and 33 P.
简述了所做的实验及其目的。
The plant/fungus combinations varied in growth and P responses. Flax ( Linum usitatissimum ) responded positively to all fungi, and medic ( Medicago truncatula ) to Glomus caledonium and G.intraradices ,but not Gigaspora rosea .Tomato( Lycopersicon esculentum )showed no positive responses.
简要叙述了关于植物生长的主要结果。
Hyphal growth in soil was very low for Gi. rosea and high for both Glomus spp.Hyphal lengths in root + hyphal compartment (RHC) and hyphal compartment (HC) were similar for G. intraradices , but much higher in HC for G.caledonium .
简述了关于菌丝长度的主要结果。
Specific activities of 33 P in plants and soil indicated that fungal P uptake made substantial contributions to five plant/fungus combinations and significant contributions to a further two. G.intraradices delivered close to 100% of the P in all three plants. G.caledonium and Gi.rosea delivered less P. The amount was not related to colonisation or to growth or P responses.
1.“contribution”这个词可以有复数。
2.简述了菌根菌对植物吸收磷的贡献率。
We conclude that: AM colonisation can result in complete inactivation of the direct P uptake pathway via root hairs and epidermis;calculations of AM contributions to P uptake from total plant P will often be highly inaccurate; and lack of plant responsiveness does not mean that an AM fungus makes no contribution to P uptake.
1.结论用一般现在时，更具有普遍性的意义。
2.后面半句话意在指出过去研究的不足。
除了上述三类之外，还有一类定调高的摘要，一般是高端的综合性刊物，如 Nature （及其子刊）或 Science 。这类摘要表达比较能吸引眼球，同时常常包含一些关键的参考文献，往往要有严格的字数限制（如150字）。
The global scale-up in demand for animal protein is the most notable dietary trend of our time.
开门见山地指出社会面临大问题，动物蛋白的需求。
Antimicrobial consumption in animals is threefold that of humans and has enabled large-scale animal protein production.
指出动物蛋白生产中的问题，紧扣主题——抗生素的用量，特别是与人用量的对比，突出问题的严重性。
The consequences for the development of antimicrobial resistance in animals have received comparatively less attention than in humans.
1.注意“for”的用法。
2.动物用量多，但是受重视程度远比人用的少，点出了科学认知上的问题。
We analyzed 901 point prevalence surveys of pathogens in developing countries to map resistance in animals.
采用第一人称。
China and India represented the largest hotspots of resistance, with new hotspots emerging in Brazil and Kenya. From 2000 to 2018, the proportion of antimicrobials showing resistance above 50% increased from 0.15 to 0.41 in chickens and from 0.13 to 0.34 in pigs.
描述量化的结果。
Escalating resistance in animals is anticipated to have important consequences for animal health and, eventually , for human health.
1.“escalating”这个词很好，表达的趋势较强烈。
2.“eventually”是两个逗号之间的副词，起到连接作用并加强语气。
Bangladesh relies heavily on groundwater for the irrigation of dry-season rice.
第一句开门见山，明确了研究的大背景。
However , the groundwater used for irrigation often contains high concentrations of arsenic, potentially jeopardizing the future of rice production in the country.
1.“however”话锋一转，引出特定的科学问题，这是许多高影响力论文立论的写法。
2.“jeopardizing”是不错的用词。
In seasonally flooded fields, topsoil arsenic concentrations decrease during the monsoon season, suggesting that flooding attenuates arsenic accumulation in the soils.
1.前半句描述常见的现象。
2.“suggesting”引导从句。
3.“attenuates”这个词也很确切，是常用的科学词汇。
4.后半句提出解释现象的假设。
Here we examine the chemistry of soil porewater and floodwater during the monsoon season in rice paddies in Munshiganj,Bangladesh, to assess whether flooding releases significant quantities of arsenic from the soils. We estimate that between 51 and 250 mg m -2 of soil arsenic is released into floodwater during the monsoon season. This corresponds to a loss of 13%-62% of the arsenic added to soils through irrigation each year. The arsenic was distributed throughout the entire floodwater column by vertical mixing and was laterally removed when the floodwater receded.
“here”可以加强语气，后面跟一般现在时；对研究描述也有用过去时的，但不能有“here”。
We conclude that monsoon floodwater removes a large amount of the arsenic added to paddy soils through irrigation, and suggest that non-flooded soils are particularly at risk of arsenic accumulation.
1.前半句是主要结论，与前面提出的假设呼应。
2.作为摘要最后一句话，通用性的表述展示了研究结果可能有更广泛的意义。
要注意的是，这是一篇发表在 Nature Geoscience 上的重要论文，作者没有罗列复杂的数据，只展示了最关键的要点（用了很少的数据），但是会给读者留下深刻的印象。国内学生在写文章时往往求全、求细，这样，文章往往显得冗长，给读者一团乱麻的感觉，主题不突出，阅后难以找出要点。英文中常常形象地用“distill”这个词，意思是不断把精华提炼出来。
Two distinct microbial processes, denitrification and anaerobic ammonium oxidation (anammox), are responsible for the release of fixed nitrogen as dinitrogen gas (N 2 ) to the atmosphere.
说明背景并引用文献，这是因为 Nature 要求Letter类型论文的第一段既是引言又是摘要。
Denitrification has been studied for over 100 years and its intermediates and enzymes are well known.
100多年来对反硝化的研究已经比较清楚，这样的表述吸引眼球。
Even though anammox is a key biogeochemical process of equal importance , its molecular mechanism is unknown, but it was proposed to proceed through hydrazine (N 2 H 4 ).
1.“even though”这个表述可强化语气，吸引注意力。
2.“of equal importance”表述重要性。
3.“…is unknown, but…”目前一无所知，但是……
Here we show that N 2 H 4 is produced from the anammox substrates ammonium and nitrite and that nitric oxide (NO) is the direct precursor of N 2 H 4 .
非常简洁地阐述了本研究的发现。
We resolved the genes and proteins central to anammox metabolism and purified the key enzymes that catalyse N 2 H 4 synthesis and its oxidation to N 2 .
1.“resolved”这个词，体现0→1的创新。
2.英式英语用“catalyse”，美式英语是“catalyze”，全文统一即可。
These results present a new biochemical reaction forging an N-N bond and fill a lacuna in our understanding of the biochemical synthesis of the N 2 in the atmosphere. Furthermore, they reinforce the role of nitric oxide in the evolution of the nitrogen cycle.
“lacuna”意为空白，是不常见的单词；常用的单词是“gap”。
这个摘要言简意赅，表达非常精准，堪称一绝。读者可以试图在里面去掉、增加或更换相关的词或句子，然后来感受差异，这样有利于提升自己的写作水平。
美国明尼苏达大学的David Tilman（戴维·蒂尔曼）教授是生态学界的泰斗级人物。本书作者（朱）有一次和他交流，欣喜地发现他早年也在英国帝国理工学院做过访问学者，而且发现两个人都是在帝国理工学院Silwood Park Campus（希尔伍德公园校区，在温莎城堡附近，是国际上生态学研究的重要基地。作者曾在那里攻读博士学位），也就有了更多的共同语言。在探讨论文的撰写问题时，他特别提到在英国期间Robert May（罗伯特·梅）教授对他的影响。Tilman教授说，他注意到May教授在写论文时经常和其他作者争论一词一句的用法，常常问“为什么用这个词？”“有没有更好的词？”“为什么在这里写个句子？”等等。Tilman教授深受启发，感到反复锤炼的重要性。Robert May是理论生态学界的殿堂式的人物，曾担任英国皇家学会主席，英国政府首席科学家，其治学态度值得后人学习。