全文获取类型
收费全文 | 29346篇 |
免费 | 4385篇 |
国内免费 | 2691篇 |
专业分类
电工技术 | 2647篇 |
综合类 | 3882篇 |
化学工业 | 2958篇 |
金属工艺 | 840篇 |
机械仪表 | 2171篇 |
建筑科学 | 1624篇 |
矿业工程 | 1126篇 |
能源动力 | 631篇 |
轻工业 | 1800篇 |
水利工程 | 926篇 |
石油天然气 | 1116篇 |
武器工业 | 474篇 |
无线电 | 3383篇 |
一般工业技术 | 2754篇 |
冶金工业 | 684篇 |
原子能技术 | 208篇 |
自动化技术 | 9198篇 |
出版年
2024年 | 72篇 |
2023年 | 349篇 |
2022年 | 715篇 |
2021年 | 861篇 |
2020年 | 994篇 |
2019年 | 872篇 |
2018年 | 929篇 |
2017年 | 1074篇 |
2016年 | 1281篇 |
2015年 | 1342篇 |
2014年 | 1940篇 |
2013年 | 1935篇 |
2012年 | 2500篇 |
2011年 | 2406篇 |
2010年 | 1944篇 |
2009年 | 1901篇 |
2008年 | 1939篇 |
2007年 | 2199篇 |
2006年 | 1824篇 |
2005年 | 1560篇 |
2004年 | 1275篇 |
2003年 | 1164篇 |
2002年 | 907篇 |
2001年 | 800篇 |
2000年 | 609篇 |
1999年 | 490篇 |
1998年 | 427篇 |
1997年 | 350篇 |
1996年 | 286篇 |
1995年 | 252篇 |
1994年 | 241篇 |
1993年 | 198篇 |
1992年 | 149篇 |
1991年 | 126篇 |
1990年 | 99篇 |
1989年 | 84篇 |
1988年 | 62篇 |
1987年 | 43篇 |
1986年 | 34篇 |
1985年 | 32篇 |
1984年 | 36篇 |
1983年 | 25篇 |
1982年 | 31篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1976年 | 4篇 |
1965年 | 5篇 |
1964年 | 4篇 |
1961年 | 3篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
51.
52.
Carmen G. Manzanarez-Quín Lilia M. Beltrán-Barrientos Adrián Hernández-Mendoza Aarón F. González-Córdova Belinda Vallejo-Cordoba 《Journal of dairy science》2021,104(4):3766-3778
The growing prevalence of obesity affects millions of people around the world and has gained increased attention over the years because it is associated with the development of other chronic degenerative diseases. Different organizations recommend lifestyle changes to treat obesity; nevertheless, other strategies in addition to lifestyle changes have recently been suggested. One of these strategies is the use of probiotics in fermented dairy products; however, a need exists to review the different studies available related to the potential antiobesity effect of these products. Because probiotic fermented dairy products that support weight management are not available in the market, there is a great opportunity for the development of functional dairy products with new lactic acid bacteria that may present this added health benefit. Thus, the purpose of this overview is to highlight the importance of probiotic fermented dairy products as potential antiobesogenic functional foods and present in vitro and in vivo studies required before this kind of product may be introduced to the market. Overall, most studies attributed the antiobesity effect of fermented dairy foods to the probiotic strains present; however, bioactive peptides released during milk fermentation may also be responsible for this effect. 相似文献
53.
This paper addresses an advanced manufacturing technology selection problem by proposing a new common-weight multi-criteria decision-making (MCDM) approach in the evaluation framework of data envelopment analysis (DEA). We improve existing technology selection models by giving a new mathematical formulation to simplify the calculation process and to ensure its use in more general situations with multiple inputs and multiple outputs. Further, an algorithm is provided to solve the proposed model based on mixed-integer linear programming and dichotomy. Compared with previous approaches for technology selection, our approach brings new contributions. First, it guarantees that only one decision-making unit (DMU) (referring to a technology) can be evaluated as efficient and selected as the best performer while maximising the minimum efficiency among all the DMUs. Second, the number of mixed-integer linear programs to solve is independent of the number of candidates. In addition, it guarantees the uniqueness of the final optimal set of common weights. Two benchmark instances are used to compare the proposed approach with existing ones. A computational experiment with randomly generated instances is further proceeded to show that the proposed approach is more suitable for situations with large datasets. 相似文献
54.
Galin Ivanov Ertugrul Bilgucu Ivelina Ivanova Milena Dimitrova 《International Journal of Dairy Technology》2020,73(3):563-569
The present study aimed to investigate the effect of somatic cell count (SCC) of raw cow's milk on the volatile organic compound (VOC) profiles of yoghurt. Test yoghurt samples were produced from three batches of cow's milk with low, medium and high SCC, respectively. The VOCs were determined by gas chromatography–mass spectrometry (GC–MS) analysis. A lower diacetyl and acetoin content and a higher content of 2‐heptanone, and butanoic and hexanoic acids were established in the yoghurt samples from batches with high SCC of above 1 000 000 cells/cm3. The increased SCC of cow's milk had a negative effect on the volatile organic compound profiles of yoghurt. 相似文献
55.
构建工程咨询机构BIM技术应用能力评价的指标体系,提出改进的熵权TOPSIS评价模型,以4个典型的工程咨询单位为例,进行BIM技术运用能力评价。研究表明,BIM行业的整体水平已经有了明显的提升,但是区域间的发展还存在一定差距。 相似文献
56.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen. 相似文献
57.
针对星座图的射频(RF)指纹识别方案中,低信噪比环境下识别准确率低的问题,提出一种基于欧式距离与幅度距离的二维识别算法来进行RF指纹识别。该方案通过对星座图进行优化处理,可从优化后的星座图中提取识别性能更好的RF指纹,再通过二维识别算法来提高识别准确率。仿真结果表明:与仅用欧式距离作为判断依据的方法相比,所提出的二维识别算法的识别准确率最高可提升8%,在设备容量为50组的情况下识别准确率为77.8%,并且从优化后的星座图中所提取的RF指纹具有更好的唯一性和稳定性。 相似文献
58.
航天发射对火箭飞行弹道数据处理的精度要求日益增高,对参与外测融合解算的雷达信息可靠性也提出了较高的要求。为解决航天发射时异常测量数据参与外测融合求解可能会导致火箭弹道精度降低的问题,提出了外测数据融合准则和短时多测元快速遴选方法,可有效识别、剔除异常测量数据,确保同目标高精度测元参与融合解算;并针对不同体制、不等精度的测量数据设计了一种最优权值快速计算方法,该方法综合考虑了测控设备的实际测量精度及布站几何对弹道精度的影响,确保在设定步长内融合权值最优。仿真结果证明该算法简单适用,可确保关键节点测控信息源的准确度,有效提高了发射场火箭弹道参数的处理精度。 相似文献
59.
60.
针对互联网中恶意域名攻击事件频发,现有域名检测方法实时性不强的问题,提出一种基于词法特征的恶意域名快速检测算法。该算法根据恶意域名的特点,首先将所有待测域名按照长度进行正则化处理后赋予权值;然后利用聚类算法将待测域名划分成多个小组,并利用改进的堆排序算法按照组内权值总和计算各域名小组优先级,根据优先级降序依次计算各域名小组中每一域名与黑名单上域名之间的编辑距离;最后依据编辑距离值快速判定恶意域名。算法运行结果表明,基于词法特征的恶意域名快速检测算法与单一使用域名语义和单一使用域名词法的恶意域名检测算法相比,准确率分别提高1.7%与2.5%,检测速率分别提高13.9%与6.8%,具有更高的准确率和实时性。 相似文献