全文获取类型
收费全文 | 67353篇 |
免费 | 5986篇 |
国内免费 | 3090篇 |
专业分类
电工技术 | 3999篇 |
技术理论 | 4篇 |
综合类 | 4331篇 |
化学工业 | 11479篇 |
金属工艺 | 3657篇 |
机械仪表 | 4344篇 |
建筑科学 | 4675篇 |
矿业工程 | 1313篇 |
能源动力 | 2040篇 |
轻工业 | 4929篇 |
水利工程 | 1212篇 |
石油天然气 | 2653篇 |
武器工业 | 484篇 |
无线电 | 9173篇 |
一般工业技术 | 9300篇 |
冶金工业 | 2940篇 |
原子能技术 | 864篇 |
自动化技术 | 9032篇 |
出版年
2024年 | 246篇 |
2023年 | 955篇 |
2022年 | 1789篇 |
2021年 | 2536篇 |
2020年 | 1827篇 |
2019年 | 1654篇 |
2018年 | 1809篇 |
2017年 | 2021篇 |
2016年 | 2086篇 |
2015年 | 2670篇 |
2014年 | 3273篇 |
2013年 | 4140篇 |
2012年 | 4345篇 |
2011年 | 4892篇 |
2010年 | 4289篇 |
2009年 | 4032篇 |
2008年 | 3979篇 |
2007年 | 3649篇 |
2006年 | 3574篇 |
2005年 | 3125篇 |
2004年 | 2307篇 |
2003年 | 2240篇 |
2002年 | 2483篇 |
2001年 | 2049篇 |
2000年 | 1684篇 |
1999年 | 1465篇 |
1998年 | 1336篇 |
1997年 | 1036篇 |
1996年 | 956篇 |
1995年 | 832篇 |
1994年 | 685篇 |
1993年 | 549篇 |
1992年 | 395篇 |
1991年 | 328篇 |
1990年 | 246篇 |
1989年 | 207篇 |
1988年 | 167篇 |
1987年 | 116篇 |
1986年 | 83篇 |
1985年 | 65篇 |
1984年 | 57篇 |
1983年 | 36篇 |
1982年 | 47篇 |
1981年 | 34篇 |
1980年 | 33篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 22篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
目的: 建立快速灵敏的LC-MS/MS法测定人血浆中阿莫西林浓度,并用于两种阿莫西林胶囊的一致性评价。方法: 采用岛津公司LCMS-8060型LC-MS/MS仪,以MRM模式测定阿莫西林(m/z 366.00/114.00)的浓度,d4-阿莫西林作内标(m/z 370.10/114.05),离子源为ESI源。色谱柱选用Waters ACQUITY BEH C18(2.1×50 mm,1.7 μm),梯度洗脱。血浆样本加入内标,经甲醇沉淀蛋白后取上清液进样检测。结果: 所建方法经验证,其线性、准确度、精密度、最低定量限、提取回收率、特异性、基质效应、稳定性等各项指标均符合CFDA的指导原则及最新核查标准要求,并较文献报道中的方法有处理简单、灵敏度高、色谱峰形好的优点。结论: 所建方法快速、灵敏,适用于人血浆中阿莫西林浓度的检测。用于一致性评价的样本实测,两种制剂生物等效。 相似文献
15.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
16.
Hyperspectral imaging (HSI) is a spectroscopic method that uses densely sampled measurements along the electromagnetic spectrum to identify the unique molecular composition of an object. Traditionally HSI has been associated with remote sensing-type applications, but recently has found increased use in biomedicine, from investigations at the cellular to the tissue level. One of the main challenges in the analysis of HSI is estimating the proportions, also called abundance fractions of each of the molecular signatures. While there is great promise for HSI in the area of biomedicine, large variability in the measurements and artifacts related to the instrumentation has slow adoption into more widespread practice. In this article, we propose a novel regularization and variable selection method called the spatial LASSO (SPLASSO). The SPLASSO incorporates spatial information via a graph Laplacian-based penalty to help improve the model estimation process for multivariate response data. We show the strong performance of this approach on a benchmark HSI dataset with considerable improvement in predictive accuracy over the standard LASSO. Supplementary materials for this article are available online. 相似文献
17.
Jin Huandong 《中国油气》2018,(2)
This paper analyzes the status quo and progress of overseas oil and gas business cooperation built by Chinese oil enterprises in 2017. With the slow recovery of the oil and gas industries as a whole, the overseas oil and gas business of Chinese oil enterprises has continued to grow in size, and all-round cooperation progress was made along the Belt and Road. Breakthroughs were made in oil and gas cooperation between China and the United States. In the meantime, new features have emerged in the overseas cooperation of Chinese enterprises, and a pattern of diversified investors has basically taken shape. 相似文献
18.
19.
20.
Neural Machine Translation (NMT) is an end-to-end learning approach for
automated translation, overcoming the weaknesses of conventional phrase-based translation
systems. Although NMT based systems have gained their popularity in commercial
translation applications, there is still plenty of room for improvement. Being the most
popular search algorithm in NMT, beam search is vital to the translation result. However,
traditional beam search can produce duplicate or missing translation due to its target
sequence selection strategy. Aiming to alleviate this problem, this paper proposed neural
machine translation improvements based on a novel beam search evaluation function. And
we use reinforcement learning to train a translation evaluation system to select better
candidate words for generating translations. In the experiments, we conducted extensive
experiments to evaluate our methods. CASIA corpus and the 1,000,000 pairs of bilingual
corpora of NiuTrans are used in our experiments. The experiment results prove that the
proposed methods can effectively improve the English to Chinese translation quality. 相似文献