全文获取类型
收费全文 | 14279篇 |
免费 | 1522篇 |
国内免费 | 966篇 |
专业分类
电工技术 | 565篇 |
综合类 | 2546篇 |
化学工业 | 637篇 |
金属工艺 | 202篇 |
机械仪表 | 826篇 |
建筑科学 | 1010篇 |
矿业工程 | 183篇 |
能源动力 | 80篇 |
轻工业 | 307篇 |
水利工程 | 180篇 |
石油天然气 | 259篇 |
武器工业 | 582篇 |
无线电 | 1388篇 |
一般工业技术 | 663篇 |
冶金工业 | 2024篇 |
原子能技术 | 70篇 |
自动化技术 | 5245篇 |
出版年
2024年 | 29篇 |
2023年 | 224篇 |
2022年 | 418篇 |
2021年 | 449篇 |
2020年 | 450篇 |
2019年 | 322篇 |
2018年 | 267篇 |
2017年 | 374篇 |
2016年 | 476篇 |
2015年 | 579篇 |
2014年 | 1150篇 |
2013年 | 914篇 |
2012年 | 1217篇 |
2011年 | 1296篇 |
2010年 | 1124篇 |
2009年 | 986篇 |
2008年 | 854篇 |
2007年 | 906篇 |
2006年 | 761篇 |
2005年 | 670篇 |
2004年 | 555篇 |
2003年 | 484篇 |
2002年 | 447篇 |
2001年 | 305篇 |
2000年 | 188篇 |
1999年 | 196篇 |
1998年 | 119篇 |
1997年 | 109篇 |
1996年 | 87篇 |
1995年 | 75篇 |
1994年 | 53篇 |
1993年 | 41篇 |
1992年 | 44篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 27篇 |
1988年 | 26篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 21篇 |
1966年 | 28篇 |
1965年 | 19篇 |
1964年 | 26篇 |
1963年 | 25篇 |
1962年 | 22篇 |
1959年 | 34篇 |
1958年 | 25篇 |
1957年 | 24篇 |
1956年 | 27篇 |
1955年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
电力线是一类形状细长、特征稀疏、随着视角的变化容易混淆在大量背景信息中的特殊障碍物,常规电力线检测识别算法得到的目标框对电力线所在位置的估计不够准确。为此,提出了一种相对角度估计方法,基于常规电力线目标检测与识别算法,并结合电力线相对角度估计,从而提高电力线的检测识别过程中所在位置的精度。相比电力线绝对角度回归的方法,提出的相对角度估计方法容易训练易收敛,计算量小,适用于实时性要求较高的应用场合。 相似文献
3.
Niken Indrati Punnanee Sumpavapol Rajnibhas Sukeaw Samakradhamrongthai Natthaporn Phonsatta Patcha Poungsombat Sakda Khoomrung Atikorn Panya 《International Journal of Food Science & Technology》2022,57(6):3760-3770
Sweet pickled mango named Ma-Muang Bao Chae-Im is a traditional preserved mango from Hat Yai, Thailand. This study investigated (I) volatile and non-volatile compound profiles of commercial Ma-Muang Bao Chae-Im and (II) their relationship to consumer preference. Untargeted metabolomics profiling was performed by gas chromatography-mass quadrupole-time of flight analysis. There were 117 volatile and 44 non-volatile compounds annotated in six commercial brands of Ma-Muang Bao Chae-Im. Furthermore, 46 volatile and 19 non-volatile compounds’ discriminant markers were found by Partial least square discriminant analysis. Among those markers, sorbic and benzoic acid were observed in several brands; moreover, the combination of both compounds altered the volatile profile, especially the ester group. Partial least square regression revealed that overall consumer liking is correlated to 1-heptanol; 1-octanol; acetoin; acetic acid, 2-phenylethyl ester; D-manitol; terpenes and terpenoids, while firmness to sucrose and L-(-)-sorbofuranose. On the other hand, most ester compounds were not related to consumer preference. 相似文献
4.
5.
近年来,通过优化飞行程序降低机场飞机噪声影响成为机场环境保护的重要研究方向。文章首先建立了基于飞机“噪声-功率-距离”数据的噪声计算模型,介绍了平均飞行航迹以及连续爬升运行(Continuous Climb Opera-tion, CCO)离场程序的相关理论,最后以大型国际机场为实例,使用飞机平均飞行航迹进行噪声预测,运用综合噪声模型计算出噪声影响面积并绘制噪声影响等值线图,比较了CCO离场相对常规的标准仪表离场(Standard Instru-ment Departure, SID)的降噪效果。结果表明,CCO离场程序可有效降低机场噪声影响,在高噪声级影响区域的降噪效果更佳。 相似文献
6.
采用超高效液相色谱⁃四极杆⁃飞行时间高分辨质谱(UPLC⁃Q⁃TOF)对4类不同类型的含聚对苯二甲酸乙二醇酯(PET)材质的食品接触材料在4 %乙酸和50 %乙醇模拟物中的迁移出的非挥发性未知物进行筛查解析。结果表明,产品在4 %乙酸模拟物的迁移风险远小于50 %乙醇模拟物,主要迁移物质为聚合单体形成的寡聚物,抗氧剂、润滑剂、胶黏剂等加工助剂以及生产加工、迁移过程中形成的非有意添加物(NIAS)物质;纯PET材质的产品迁移物质较少,多层复合材料迁移物质较多。复合材质的产品中,PET材质可能在生产时添加了己二酸、癸二酸、新戊二醇等物质,进行了改性处理;此外,部分迁移物质会与模拟物中的乙醇发生反应,生成新的NIAS物质。 相似文献
7.
Deunsol Hwang Jong-Beom Seo Hun-Young Park Jisu Kim Kiwon Lim 《International journal of molecular sciences》2021,22(2)
While exercise training (ET) is an efficient strategy to manage obesity, it is recommended with a dietary plan to maximize the antiobesity functions owing to a compensational increase in energy intake. Capsiate is a notable bioactive compound for managing obesity owing to its capacity to increase energy expenditure. We aimed to examine whether the antiobesity effects of ET can be further enhanced by capsiate intake (CI) and determine its effects on resting energy expenditure and metabolic molecules. Mice were randomly divided into four groups (n = 8 per group) and fed high-fat diet. Mild-intensity treadmill ET was conducted five times/week; capsiate (10 mg/kg) was orally administered daily. After 8 weeks, resting metabolic rate and metabolic molecules were analyzed. ET with CI additively reduced the abdominal fat rate by 18% and solely upregulated beta-3-adrenoceptors in adipose tissue (p = 0.013) but did not affect the metabolic molecules in skeletal muscles. Surprisingly, CI without ET significantly increased the abdominal fat rate (p = 0.001) and reduced energy expenditure by 9%. Therefore, capsiate could be a candidate compound for maximizing the antiobesity effects of ET by upregulating beta-3-adrenoceptors in adipose tissue, but CI without ET may not be beneficial in managing obesity. 相似文献
8.
The integration of computer theory and practice in higher vocational colleges is the necessary condition to realize the train-
ing of professional talents and improve the comprehensive quality of skilled talents. It is also the problem that needs to be solved
first in the teaching of computer major in higher vocational colleges. This paper firstly introduces the definition and connotation of
the integration of computer theory and practice, discusses on its construction objectives and basic concepts, then analyzes the con-
struction value of the integration of computer theory and practice, including the contents of employment, professional teaching, cur-
riculum supporting and qualification examination, finally discusses on the construction scheme of the training room of the integra-
tion of computer theory and practice, and gives the objective evaluation of the construction results, hoping to effectively improve the
level of the integration of computer theory and practice, and achieve the sustainable development of teaching. 相似文献
9.
10.
针对在地震属性应用中难以精细识别煤层裂缝发育区边界的难题,开展了基于人工监督神经网络技术的煤层裂缝发育区应用研究。从地震资料中获取倾角导向体以提取高质量的地震属性,以多属性为指导进行人工拾取样点,并基于多层感知器进行神经网络机器训练学习,建立裂缝的最优属性集,拓展整体数据后获得裂缝概率体,从而识别划分出煤层裂缝发育区。该技术在山西阳泉新元矿区进行了应用,煤层裂缝发育区的识别结果明显优于属性直接识别,但勘探区内暂无钻井资料,预测效果还有待进一步验证。 相似文献