全文获取类型
| 收费全文 | 322篇 |
| 免费 | 27篇 |
| 国内免费 | 18篇 |
专业分类
| 综合类 | 12篇 |
| 化学工业 | 32篇 |
| 金属工艺 | 3篇 |
| 机械仪表 | 7篇 |
| 建筑科学 | 37篇 |
| 矿业工程 | 1篇 |
| 能源动力 | 1篇 |
| 轻工业 | 75篇 |
| 水利工程 | 11篇 |
| 石油天然气 | 4篇 |
| 无线电 | 33篇 |
| 一般工业技术 | 29篇 |
| 冶金工业 | 16篇 |
| 原子能技术 | 3篇 |
| 自动化技术 | 103篇 |
出版年
| 2025年 | 6篇 |
| 2024年 | 3篇 |
| 2023年 | 11篇 |
| 2022年 | 19篇 |
| 2021年 | 21篇 |
| 2020年 | 17篇 |
| 2019年 | 9篇 |
| 2018年 | 9篇 |
| 2017年 | 13篇 |
| 2016年 | 11篇 |
| 2015年 | 12篇 |
| 2014年 | 20篇 |
| 2013年 | 19篇 |
| 2012年 | 20篇 |
| 2011年 | 27篇 |
| 2010年 | 20篇 |
| 2009年 | 13篇 |
| 2008年 | 11篇 |
| 2007年 | 9篇 |
| 2006年 | 9篇 |
| 2005年 | 22篇 |
| 2004年 | 14篇 |
| 2003年 | 6篇 |
| 2002年 | 6篇 |
| 2001年 | 10篇 |
| 2000年 | 6篇 |
| 1998年 | 5篇 |
| 1997年 | 2篇 |
| 1995年 | 3篇 |
| 1994年 | 3篇 |
| 1993年 | 2篇 |
| 1992年 | 2篇 |
| 1991年 | 1篇 |
| 1990年 | 1篇 |
| 1988年 | 1篇 |
| 1987年 | 2篇 |
| 1958年 | 1篇 |
| 1954年 | 1篇 |
排序方式： 共有367条查询结果，搜索用时 15 毫秒
311.
我国一些上世纪兴建的桥梁因各种原因在现阶段使用中出现病害,须对其进行适当的加固与修补以确保安全。在对桥梁常见病害性状进行归纳的基础上,依据若干典型加固施工成功案例讨论分析了常见桥梁病害的应对措施及施工方法,所总结的一些经验可为与之类似的桥梁加固改造工程提供借鉴。 相似文献
312.
Jack M. Tipping 《臭氧:科学与工程》1987,9(2):141-152
Tests conducted with a pilot scale ozone system to control the infective stage of the fish Pathogen Ceratomvya shasta found the minimum effective ozone dose to be a CT value (ozone residual x minutes of retention) of 1.23. Mortality of summer steelhead reared to, term on ozonated and raw river water was 1.4% and 81.2% permil; respectively. Test fish were significantly larger at the end of the rearing period. A full production system for the hatchery has been recommended. 相似文献
313.
Sergio Alexandre Alcantara Santos Luiz Marcos Frediani Portela Ana Carolina Lima Camargo Flavia Bessi Constantino Ketlin Thassiani Colombelli Matheus Naia Fioretto Renato Mattos Bruno Evaristo de Almeida Fantinatti Michela Alessandra Denti Silvano Piazza Srgio Luis Felisbino Elena Zambrano Luis Antonio Justulin 《International journal of molecular sciences》2022,23(23)
314.
Cutaneous Leishmaniasis (CL) is an endemic vector-borne disease in the Middle East and a worldwide public health problem. The spread of CL is highly associated with the socio-ecological interactions of vectors, hosts and the environment. The heterogeneity of these interactions has hindered CL modeling for healthcare preventive measures in endemic areas. In this study, an agent-based model (ABM) is developed to simulate the dynamics of CL spread based on a Geographic Automata System (GAS). A Susceptible-Exposed-Infected-Recovered (SEIR) approach together with Bayesian modeling has been applied in the ABM to explore the spread of CL. The model is then adapted locally for Isfahan Province, an endemic area in central Iran. The results from the model indicate that desertification areas are the main origin of CL, and riverside population centers have the potential to host more sand fly exposures and should receive more preventive measures from healthcare authorities. The results also show that healthcare service accessibility prevented exposures from becoming infected and areas with new inhabitants experienced more infections from same amount of sand fly exposures. 相似文献
315.
Finn Gyntelberg Poul Suadicani Jan Wohlfahrt Nielsen Peder Skov Ole Valbjrn Peter A. Nielsen Thomas Schneider Ole Jrgensen Peder Wolkoff C. K. Wilkins Suzanne Gravesen Sven Norn 《Indoor air》1994,4(4):223-238
Background. In the Danish Town Hall Study\" it has previously been shown that the sick building syndrome is a widespread phenomenon. This has given rise to speculations as to whether biologically active components in dust or whether absorbed organic gases and vapours in the indoor climate may be partly responsible for the sick building syndrome. Therefore, we wished to study whether qualitative conditions in dust, of a physical, chemical, and biological nature, are related to the prevalence of symptoms of the sick building syndrome. Material and methods. The study included 12 town halls in the Copenhagen area. A total of 870 persons participated, 584 women and 286 men. All the participants filled out a questionnaire regarding health and working conditions, and dust samples were collected with a special vacuum cleaner in the working environment of the participants, after which the contents of inorganic and organic particles as well as of human source fragments the (hair, nails, skin) and various fibres were determined. Results. There was a significant correlation (P<0.05) between the prevalence of gram-negative bacteria in the indoor climate dust, and general symptoms (fatigue, heavy-headedness, headache, dizziness, concentration problems) (corr.coeff.=0.73), as well as symptoms from the mucous membranes of the upper respiratory tract (corr.coeff.=0.76). Also, there was a significant relation between the prevalence of particles in the dust and the prevalence of symptoms from the mucous membranes (corr.coeff.=0.81). There was a strong and significant correlation between the total amount of volatile organic components (TVOC) and lack of concentration (corr.coeff. =0.85) and feeling heavy-headed (corr.coeff.=0.72). Macromolecular dust (potentially allergenetic material) was significantly correlated to the prevalence of headache and general malaise/dizziness (corr.coeff.=0.66), while the ability of the dust to liberate histamine was significantly related to the prevalence of general malaise, dizziness (corr.coeff.=0.65) and lack of concentration (corr.coeff. =0.58). Further analyses including a number of potential confounders did not change the results of the above analyses. Conclusion. The results of this study support the hypothesis that qualitative properties of dust are important to the sick building syndrome. The study was based on relatively few buildings, but nevertheless strong correlations were found. In perspective, epidemiological intervention studies should be carried out to investigate whether minimizing the amount of both dust and bacteria in the indoor climate affect the prevalence of sick building syndrome. 相似文献
316.
谈学校体育中运动性病疾的成因及其对策 总被引：1，自引：0，他引：1
随着学生参与体育活动人数的增多,与运动有关的运动性疾病的发生率也有所增加,这对学校深入开展体育运动带来不必要的负面影响。本文在系统分析运动性疾病成因的基础上,根据学校体育运动的具体实际,提出了相应的预防对策。 相似文献
317.
本文论述了心理健康与疾病的关系,着重进行了高校人群心理健康的研究,并对如何防止高校人群心理疾病提出了自己的见解。 相似文献
318.
四氯化碳急性肝损伤敏感指标的研究 总被引：21，自引：0，他引：21
为研究四氯化碳急性肝损伤后各项生化指标及病理损伤的时间－反应关系,选用Ｗｉｓｔａｒ种雄性大鼠,随机分为５组,每组１０只。试验组动物给予２％ＣＣＬ４,灌胃１６０ｍｇ／ｋｇ ＢＷ,阴性对照组给予植物油。分别于染毒后１２、２４、４８、７２ｈ（对照组给油后２４ｈ）处死动物取静脉血测定血清ＧＰＴ、ＧＯＴ、ＴＧ含量,大鼠染毒后血清ＧＰＴ、ＧＯＴ含量显性升高,２４ｈ达到峰值后逐渐下降,７２ｈ接近正常;１２ｈ肝 相似文献
319.
阿尔茨海默病(AD)是一种神经退行性疾病。随着脑医学影像的发展,对AD诊断的精确度也在进一步提高,但对AD的诊断,客观上仍缺少好的生物标记。为寻找到AD的更稳定的生物标记,利用海马的影像组学特征对海马的信号强度、形状、灰度阶梯分布等特征进行刻画,通过方差分析(ANOVA)和事后检验,在统计学上寻找出正常对照(NC)、AD、轻度认知损害(MCI)之间存在差异的特征;通过与被试的简易智能状况检查(MMSE)评分进行相关性分析,找寻与MMSE评分相关性较高的特征;利用支持向量机(SVM)构建一个对AD和NC分类的模型,交叉验证得到的正确率为86%。结果表明,海马的影像组学特征是一个很好的生物标记,能对AD进行有效的早期识别。 相似文献
320.
阿尔茨海默症(AD)分类有助于在AD早期阶段及时采取针对性的治疗和干预措施,对降低老年群体的AD发病率和延缓AD疾病进展具有重要意义。该文提出一种改进的高斯模糊逻辑特征选择方法,首先采用互信息量和方差齐性分析两种方法给出特征重要性评分并分别进行归一化,然后使用改进的高斯模糊逻辑方法对其加权得到最终的特征重要性评分,最后依据特征重要性评分选取特征。该文还使用逻辑回归、随机森林、LightGBM、支持向量机和深度前馈网络作为初级分类器,多项式朴素贝叶斯分类器作为次级分类器,构建异质集成分类器,利用选取的特征进行AD分类。在TADPOLE数据集上进行实验,实验结果证实了所提特征选择方法是有效的,且采用所提特征选择方法,基于多项式朴素贝叶斯的异质集成分类器在AD分类上的性能要优于传统分类器。 相似文献