全文获取类型
收费全文 | 12197篇 |
免费 | 702篇 |
国内免费 | 608篇 |
专业分类
电工技术 | 111篇 |
技术理论 | 5篇 |
综合类 | 1908篇 |
化学工业 | 893篇 |
金属工艺 | 121篇 |
机械仪表 | 325篇 |
建筑科学 | 2102篇 |
矿业工程 | 77篇 |
能源动力 | 82篇 |
轻工业 | 2592篇 |
水利工程 | 83篇 |
石油天然气 | 80篇 |
武器工业 | 9篇 |
无线电 | 462篇 |
一般工业技术 | 869篇 |
冶金工业 | 227篇 |
原子能技术 | 69篇 |
自动化技术 | 3492篇 |
出版年
2024年 | 55篇 |
2023年 | 135篇 |
2022年 | 260篇 |
2021年 | 334篇 |
2020年 | 334篇 |
2019年 | 299篇 |
2018年 | 273篇 |
2017年 | 330篇 |
2016年 | 323篇 |
2015年 | 332篇 |
2014年 | 784篇 |
2013年 | 580篇 |
2012年 | 872篇 |
2011年 | 911篇 |
2010年 | 877篇 |
2009年 | 859篇 |
2008年 | 796篇 |
2007年 | 913篇 |
2006年 | 826篇 |
2005年 | 623篇 |
2004年 | 615篇 |
2003年 | 458篇 |
2002年 | 341篇 |
2001年 | 265篇 |
2000年 | 234篇 |
1999年 | 197篇 |
1998年 | 146篇 |
1997年 | 114篇 |
1996年 | 84篇 |
1995年 | 74篇 |
1994年 | 59篇 |
1993年 | 45篇 |
1992年 | 34篇 |
1991年 | 23篇 |
1990年 | 30篇 |
1989年 | 16篇 |
1988年 | 15篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
许磊 《扬州大学烹饪学报》2007,24(4):47-49
宴席是人们日常饮食的重要组成部分,无论中餐宴席还是西餐宴席,上菜顺序都有一定规范,但有待完善。根据食物营养成分和饮食保健理论,宴席的科学合理的上菜顺序是:水果、汤莱、蔬菜与主食、荤菜。 相似文献
992.
993.
994.
995.
提出一种结合L1范数模型和内点理论的潮流计算方法,利用基于扰动KKT条件的原始-对偶内点算法进行一般潮流问题求解.与以前的最小潮流法相比,该方法简单、求解易于收敛、易于程序实现,便于对病态系统求解,并同时能判断潮流方程是否有解. 相似文献
996.
In order to meet the requirement of customised services for online communities, sentiment classification of online reviews has been applied to study the unstructured reviews so as to identify users’ opinions on certain products. The purpose of this article is to select features for sentiment classification of Chinese online reviews with techniques well performed in traditional text classification. First, adjectives, adverbs and verbs are identified as the potential text features containing sentiment information. Then, four statistical feature selection methods, such as document frequency (DF), information gain (IG), chi-squared statistic (CHI) and mutual information (MI), are adopted to select features. After that, the Boolean weighting method is applied to set feature weights and construct a vector space model. Finally, a support vector machine (SVM) classifier is employed to predict the sentiment polarity of online reviews. Comparative experiments are conducted based on hotel online reviews in Chinese. The results indicate that the highest accuracy of the sentiment classification of Chinese online reviews is achieved by taking adjectives, adverbs and verbs together as the feature. Besides that, different feature selection methods make distinct performances on sentiment classification, as DF performs the best, CHI follows and IG ranks the last, whereas MI is not suitable for sentiment classification of Chinese online reviews. This conclusion will be helpful to improve the accuracy of sentiment classification and be useful for further research. 相似文献
997.
为了将秘密信息嵌入到特定的载体之中,实现安全、高效的信息传输,以达到安全通信或版权保护等目的,针对中文文本设计了基于字体的信息隐藏算法.分析了文本信息隐藏的研究现状和存在的不足,根据不同的安全和嵌入率的需求,给出了3种对电子文本、打印文本、手写文本等皆适用的秘密信息嵌入算法,并且通过数学推导,对3种嵌入方式的嵌入率和嵌入效率等进行了分析比较.对算法的安全性进行了分析,并给出了增强安全性的手段. 相似文献
998.
Semantic Role Labeling of Chinese Nominal Predicates with Dependency-Driven Constituent Parse Tree Structure 下载免费PDF全文
This paper explores a tree kernel based method for semantic role labeling (SRL) of Chinese nominal predicates via a convolution tree kernel. In particular, a new parse tree representation structure, called dependency-driven constituent parse tree (D-CPT), is proposed to combine the advantages of both constituent and dependence parse trees. This is achieved by directly representing various kinds of dependency relations in a CPT-style structure, which employs dependency relation types instead of phrase labels in CPT (Constituent Parse Tree). In this way, D-CPT not only keeps the dependency relationship information in the dependency parse tree (DPT) structure but also retains the basic hierarchical structure of CPT style. Moreover, several schemes are designed to extract various kinds of necessary information, such as the shortest path between the nominal predicate and the argument candidate, the support verb of the nominal predicate and the head argument modified by the argument candidate, from D-CPT. This largely reduces the noisy information inherent in D-CPT. Finally, a convolution tree kernel is employed to compute the similarity between two parse trees. Besides, we also implement a feature-based method based on D-CPT. Evaluation on Chinese NomBank corpus shows that our tree kernel based method on D-CPT performs significantly better than other tree kernel-based ones and achieves comparable performance with the state-of-the-art feature-based ones. This indicates the effectiveness of the novel D-CPT structure in representing various kinds of dependency relations in a CPT-style structure and our tree kernel based method in exploring the novel D-CPT structure. This also illustrates that the kernel-based methods are competitive and they are complementary with the feature- based methods on SRL. 相似文献
999.
This study examined the effects of display method, text display rate, and observation angle on comprehension performance and subjective preferences for Chinese characters presented on an LED display. The factors and levels studied were as follows: four text display methods (rapid serial visual presentation ‘RSVP’, leading, paged view scrolling, and continuous scrolling), three text display rates (160 characters per min ‘cpm’, 240 cpm, and 320 cpm), and seven observation angles (−75°, −60°, −30°, 0°, 30°, 60°, and 75°). The results indicated that a display rate of 160 cpm was in general superior to 240 and 320 cpm for comprehension scores and subjective evaluations. The effects of display method and observation angle were found to be non significant. However, there was a significant interaction between display method and display rate. The results of this study were used to make ergonomics recommendations applicable to LED displays for determining optimum dynamic text display methods for Chinese characters. 相似文献
1000.