全文获取类型
收费全文 | 98132篇 |
免费 | 16107篇 |
国内免费 | 10294篇 |
专业分类
电工技术 | 10730篇 |
技术理论 | 4篇 |
综合类 | 12887篇 |
化学工业 | 3096篇 |
金属工艺 | 1892篇 |
机械仪表 | 6471篇 |
建筑科学 | 5443篇 |
矿业工程 | 2665篇 |
能源动力 | 2306篇 |
轻工业 | 4156篇 |
水利工程 | 3091篇 |
石油天然气 | 4744篇 |
武器工业 | 1990篇 |
无线电 | 13921篇 |
一般工业技术 | 6093篇 |
冶金工业 | 1426篇 |
原子能技术 | 527篇 |
自动化技术 | 43091篇 |
出版年
2024年 | 263篇 |
2023年 | 1656篇 |
2022年 | 3282篇 |
2021年 | 3652篇 |
2020年 | 3975篇 |
2019年 | 3177篇 |
2018年 | 3030篇 |
2017年 | 3341篇 |
2016年 | 3939篇 |
2015年 | 4815篇 |
2014年 | 6992篇 |
2013年 | 6414篇 |
2012年 | 8554篇 |
2011年 | 8832篇 |
2010年 | 6922篇 |
2009年 | 7146篇 |
2008年 | 7191篇 |
2007年 | 8063篇 |
2006年 | 6554篇 |
2005年 | 5501篇 |
2004年 | 4400篇 |
2003年 | 3560篇 |
2002年 | 2605篇 |
2001年 | 2124篇 |
2000年 | 1726篇 |
1999年 | 1385篇 |
1998年 | 1062篇 |
1997年 | 915篇 |
1996年 | 715篇 |
1995年 | 546篇 |
1994年 | 450篇 |
1993年 | 345篇 |
1992年 | 284篇 |
1991年 | 179篇 |
1990年 | 181篇 |
1989年 | 156篇 |
1988年 | 88篇 |
1987年 | 48篇 |
1986年 | 58篇 |
1985年 | 51篇 |
1984年 | 48篇 |
1983年 | 49篇 |
1982年 | 39篇 |
1981年 | 25篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 15篇 |
1975年 | 16篇 |
1959年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
提出了一种基于FCOS神经网络的小建筑物目标检测算法,针对FCOS模型在特征提取阶段提取到的小建筑物目标特征较少问题,引入多尺度检测和可变形卷积方式,加强网络对小建筑物目标的特征提取能力,并通过改进后的SGE注意力机制降低特征图中的干扰噪声权重。改进后的网络可以提取到更多的小建筑物目标特征,对环境干扰噪声的鲁棒性更强。在自己搭建的数据集上进行了实验测试,结果表明,在相同环境下网络改进后建筑物的整体检测准确率提升了1.7%,其中对小建筑物目标提升了3.6%,减少了小建筑物目标漏检、误检的问题。 相似文献
2.
3.
Anisse Pereira Hong C. Lee Robert Lammert Jr. Cailyn Wolberg Jr. Danyi Ma Chad Immoos Federico Casassa Iksoon Kang 《International Journal of Food Science & Technology》2022,57(3):1814-1823
This study was conducted to evaluate the effect of red-wine grape pomaces on the quality and sensory attributes of beef hamburger patties. Both phenolic content and antioxidant activity were assessed using Syrah, Merlot and Cabernet Sauvignon pomaces. Following the assessment, hamburger patties were prepared with Merlot pomace at 0%, 2% and 4% for the patty quality and sensory attributes. Grape seeds possessed significantly higher phenolics and antioxidant activities over the seedless pomace (P < 0.05), whereas no significant difference was found for phenolics and antioxidant activities within the seeds and seedless pomaces. The patty pH decreased as the pomace was added for 2% and 4%. Colour values (L*, a* and b*) of patties lowered as the pomace was added. Allo-Kramer shear force and hardness values increased while cooking yield decreased (P < 0.05) with the addition of pomace. No significant difference between control and Merlot patties was found for flavour, juiciness and colour, whereas lower sensory attributes were observed for texture, taste and overall acceptability. It is observed that the addition of fermented red-wine grape pomace provides hamburger patties with health promoting factors such as antioxidant and other functional components, but it also provided darker, sourer and lower cooking yield. 相似文献
4.
5.
为缓解我国水、能源和粮食资源紧张问题,促进资源可持续利用,构建水-能源-粮食系统,利用耦合协调度模型对我国的30个省(自治区、直辖市)进行测算,并利用空间杜宾模型分析主要影响因素。结果表明:2003—2017年,我国能源、粮食评价[JP]指数高于水资源评价指数,系统综合评价指数逐年递增;大部分省份耦合协调度处于初级协调水平且呈现逐年上升的态势,个别省份耦合协调度濒临失调;耦合协调度空间自相关性较强,虽有明显波动,但是呈现逐年加强的态势;影响耦合协调度的主要因素有从业人口数、固定资产投资额、人均生产总值、人口总数、[JP]文盲人口占比、工业污染排放、城镇化。 相似文献
6.
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
7.
针对配电自动化终端优化布局问题,提出了一种基于重要度排序的终端优化布局方法。首先以等年值综合费用为目标函数,供电可靠性和投入产出比为双重约束建立了配电自动化终端优化布局模型。然后通过分析配电自动化终端对供电可靠性提升的影响,给出各个节点的“二遥”及“三遥”终端安装重要度定义及计算公式。最后采用枚举法确定最优终端安装数量,基于节点终端安装重要度排序确定终端的最优安装位置。该方法考虑了已布局节点对剩余节点终端安装重要度的影响,能够在降低计算量的同时兼顾布局合理性。运用所提方法RBTS-BUS2系统及扩充模型进行终端优化布局并与智能优化算法的布局结果进行对比,验证了本文方法的有效性及优越性。 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(6):4062-4074
In this work, coupling effects of water content, temperature, oxygen density, and polytetrafluoroethylene (PTFE) loading on oxygen transport through an ionomer thin film on a platinum surface in a catalyst layer of a proton exchange membrane (PEM) fuel cell are investigated using molecular dynamics approach. Taguchi orthogonal algorithm is employed to comprehensively analyze the coupling effects in a limited number of cases. It is found that the effect of operation temperature is the weakest among the four factors, which has the smallest effect index 14.4. Coupling effects including the PTFE loadings on the oxygen transfer through the ionomer thin film is uncovered. Less PTFE loadings should be beneficial for the oxygen transfer. The chemical potential gradient is considered as the major driven force for the oxygen transport through the ionomer thin film, and oxygen density is the dominating factor, significantly affecting the chemical potential in the thin film. 相似文献
9.
10.
Farzaneh Khorasani Morteza Mohammadi Zanjireh Mahdi Bahaghighat Qin Xin 《计算机系统科学与工程》2022,40(3):1085-1098
With a sharp increase in the information volume, analyzing and retrieving this vast data volume is much more essential than ever. One of the main techniques that would be beneficial in this regard is called the Clustering method. Clustering aims to classify objects so that all objects within a cluster have similar features while other objects in different clusters are as distinct as possible. One of the most widely used clustering algorithms with the well and approved performance in different applications is the k-means algorithm. The main problem of the k-means algorithm is its performance which can be directly affected by the selection in the primary clusters. Lack of attention to this crucial issue has consequences such as creating empty clusters and decreasing the convergence time. Besides, the selection of appropriate initial seeds can reduce the cluster’s inconsistency. In this paper, we present a new method to determine the initial seeds of the k-mean algorithm to improve the accuracy and decrease the number of iterations of the algorithm. For this purpose, a new method is proposed considering the average distance between objects to determine the initial seeds. Our method attempts to provide a proper tradeoff between the accuracy and speed of the clustering algorithm. The experimental results showed that our proposed approach outperforms the Chithra with 1.7% and 2.1% in terms of clustering accuracy for Wine and Abalone detection data, respectively. Furthermore, achieved results indicate that comparing with the Reverse Nearest Neighbor (RNN) search approach, the proposed method has a higher convergence speed. 相似文献