全文获取类型
收费全文 | 1477篇 |
免费 | 191篇 |
国内免费 | 33篇 |
专业分类
电工技术 | 22篇 |
综合类 | 32篇 |
化学工业 | 307篇 |
金属工艺 | 9篇 |
机械仪表 | 57篇 |
建筑科学 | 56篇 |
矿业工程 | 24篇 |
能源动力 | 88篇 |
轻工业 | 764篇 |
水利工程 | 93篇 |
石油天然气 | 11篇 |
无线电 | 61篇 |
一般工业技术 | 62篇 |
冶金工业 | 4篇 |
原子能技术 | 7篇 |
自动化技术 | 104篇 |
出版年
2024年 | 8篇 |
2023年 | 61篇 |
2022年 | 105篇 |
2021年 | 90篇 |
2020年 | 103篇 |
2019年 | 94篇 |
2018年 | 94篇 |
2017年 | 62篇 |
2016年 | 77篇 |
2015年 | 109篇 |
2014年 | 117篇 |
2013年 | 95篇 |
2012年 | 138篇 |
2011年 | 151篇 |
2010年 | 94篇 |
2009年 | 68篇 |
2008年 | 50篇 |
2007年 | 68篇 |
2006年 | 61篇 |
2005年 | 16篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有1701条查询结果,搜索用时 296 毫秒
81.
82.
The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice. 相似文献
83.
84.
棉油皂脚中植物甾醇的提取工艺研究 总被引:2,自引:0,他引:2
为了探索从棉油皂脚中提取植物甾醇的工艺条件。以皂脚为原料,通过单因素和正交实验优化最佳工艺条件,并对粗品进行纯化,以高效液相色谱法测定的甾醇含量为考察指标。植物甾醇提取的最佳工艺为:皂化料液比1∶3,90℃下皂化3 h,用乙酸乙酯进行萃取,料液比为1∶20,粗甾醇的提取率为75.6%,其中提取得到的β-谷甾醇和菜油甾醇的纯度分别为(66.5±0.47)%、(5.67±0.08)%,其经无水乙醇重结晶两次后,纯度可达91.8%。结果表明最佳提取工艺重现性较好;HPLC法测定甾醇含量结果准确可靠。 相似文献
85.
CO余热锅炉是催化裂化装置的关键部件,影响整套装置的安全经济运行。针对高温烟气热能浪费、环境污染等问题,设计了一种高温烟气回收装置,并对关键结构气风混合室进行三维实体建模,通过CFD前处理软件Gambit进行网格划分,最后导入Fluent软件对该结构进行数值流场模拟,结果表明该装置能够有效回收高温烟气、减少热量损耗、降低生产成本,具有很好的经济与社会效益。 相似文献
86.
87.
目的研究北疆部分地区食源性大肠杆菌的优势血清型、毒力基因和耐药基因的相关性。方法采用玻片凝集法测定了大肠杆菌血清型分布,PCR方法调查11种耐药基因和9种毒力基因。结果血清试验,定型菌株26株,分别属于17种血清型,其中O1、O115为优势血清型;PCR结果表明,不含有所检测耐药基因的分离株占12.50%,至少含有2种以及以上的分离株占50.00%,分离株对blaOXA基因携带率高达57.14%;检出率较高的毒力基因为fimC(64.29%)和fimA(25.00%)。结论 O1、O115为主要的血清型,2种血清型菌株拥有的耐药基因谱和毒力基因谱不相同。 相似文献
88.
《Computational statistics & data analysis》2008,52(12):6027-6043
Spatial cluster modelling of small area disease incidence and mortality has previously focused on clusters where excess risk is distributed around fixed points, and the aim is the reconstruction of these points (cluster centers). Often there is a need to assess clusters of a different form, such as around roads or river systems. These clusters are often linear or can be approximated by combinations of several linear segments. In this paper the recovery of point and line clusters is considered jointly. An example application is given where both linear or point clustering could be present. 相似文献
89.
《Expert systems with applications》2008,34(4):1054-1062
This paper intends to an integrated view of implementing automated diagnostic systems for breast cancer detection. The major objective of the paper is to be a guide for the readers, who want to develop an automated decision support system for detection of breast cancer. Because of the importance of making the right decision, better classification procedures for breast cancer have been searched. The classification accuracies of different classifiers, namely multilayer perceptron neural network (MLPNN), combined neural network (CNN), probabilistic neural network (PNN), recurrent neural network (RNN) and support vector machine (SVM), which were trained on the attributes of each record in the Wisconsin breast cancer database, were compared. The purpose was to determine an optimum classification scheme with high diagnostic accuracy for this problem. This research demonstrated that the SVM achieved diagnostic accuracies which were higher than that of the other automated diagnostic systems. 相似文献
90.
新疆天然骨料粉煤灰混凝土抗渗性研究 总被引:2,自引:0,他引:2
新疆混凝土工程天然骨料料源丰富,水工混凝土骨料几乎全部采用天然骨料,针对这一特点,结合当地原材料情况,通过实验探讨了影响新疆天然骨料粉煤灰混凝土抗渗性的主要因素,提出了天然骨料粉煤灰混凝土提高抗渗性的最大水胶比和粉煤灰掺量上限值等指标。 相似文献