全文获取类型
收费全文 | 22275篇 |
免费 | 1476篇 |
国内免费 | 1289篇 |
专业分类
电工技术 | 613篇 |
技术理论 | 5篇 |
综合类 | 3246篇 |
化学工业 | 2361篇 |
金属工艺 | 858篇 |
机械仪表 | 951篇 |
建筑科学 | 3100篇 |
矿业工程 | 422篇 |
能源动力 | 268篇 |
轻工业 | 2637篇 |
水利工程 | 358篇 |
石油天然气 | 1472篇 |
武器工业 | 237篇 |
无线电 | 1318篇 |
一般工业技术 | 1169篇 |
冶金工业 | 620篇 |
原子能技术 | 143篇 |
自动化技术 | 5262篇 |
出版年
2024年 | 51篇 |
2023年 | 209篇 |
2022年 | 419篇 |
2021年 | 520篇 |
2020年 | 518篇 |
2019年 | 495篇 |
2018年 | 426篇 |
2017年 | 585篇 |
2016年 | 581篇 |
2015年 | 628篇 |
2014年 | 1264篇 |
2013年 | 1084篇 |
2012年 | 1471篇 |
2011年 | 1495篇 |
2010年 | 1385篇 |
2009年 | 1410篇 |
2008年 | 1371篇 |
2007年 | 1760篇 |
2006年 | 1492篇 |
2005年 | 1200篇 |
2004年 | 1144篇 |
2003年 | 987篇 |
2002年 | 782篇 |
2001年 | 717篇 |
2000年 | 573篇 |
1999年 | 512篇 |
1998年 | 401篇 |
1997年 | 318篇 |
1996年 | 274篇 |
1995年 | 192篇 |
1994年 | 158篇 |
1993年 | 130篇 |
1992年 | 106篇 |
1991年 | 73篇 |
1990年 | 62篇 |
1989年 | 62篇 |
1988年 | 40篇 |
1987年 | 24篇 |
1986年 | 27篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 16篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(36):16121-16131
Ammonia is considered as a promising hydrogen or energy carrier. Ammonia absorption or adsorption is an important aspect for both ammonia removal, storage and separation applications. To these ends, a wide range of solid and liquid sorbents have been investigated. Among these, the deep eutectic solvent (DES) is emerging as a promising class of ammonia absorbers. Herein, we report a novel type of DES, i.e., metal-containing DESs for ammonia absorption. Specifically, the NH3 absorption capacity is enhanced by ca. 18.1–36.9% when a small amount of metal chlorides, such as MgCl2, MnCl2 etc., are added into a DES composed of resorcinol (Res) and ethylene glycol (EG). To our knowledge, the MgCl2/Res/EG (0.1:1:2) DES outperforms most of the reported DESs. The excellent NH3 absorption performances of metal–containing DESs have been attributed to the synergy of Lewis acid–base and hydrogen bonding interactions. Additionally, good reversibility and high NH3/CO2 selectivity are achieved over the MgCl2/Res/EG (0.1:1:2) DES, which enables it to be a potential NH3 absorber for further investigations. 相似文献
2.
Ava Kwong Cecilia Y. S. Ho Vivian Y. Shin Chun Hang Au Tsun Leung Chan Edmond S. K. Ma 《International journal of molecular sciences》2021,22(2)
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers. 相似文献
3.
4.
Li Lin Harry Haoxiang Wang Yuewei Liu Ciyong Lu Weiqing Chen Vivian Yawei Guo 《Indoor air》2021,31(6):2158-2166
A cross-sectional study was conducted to investigate the impact of solid fuel use for heating and cooking on blood pressure (BP) and hypertension, using data from the China Health and Retirement Longitudinal Study (CHARLS). The primary fuels used for indoor heating and cooking were collected by questionnaires, respectively. Hypertension was defined based on self-report of physician's diagnosis, and/or measured BP, and/or anti-hypertensive medication use. Multivariate logistic regression models were constructed to assess the associations. Among 10 450 eligible participants, 68.2% and 57.2% used indoor solid fuel for heating and cooking, respectively. Compared with none/clean fuel users, solid fuel for heating was associated with elevated BP (adjusted β: 2.02, 95% CI: 1.04–3.01 for systolic BP; adjusted β: 1.36, 95% CI: 0.78–1.94 for diastolic BP) and increased risk of hypertension (adjusted odds ratio: 1.15, 95% CI: 1.03–1.29). The impact of indoor solid fuel for heating on BP was more evident in rural and north residents, and hypertensive patients. We did not detect any significant associations between solid fuel use for cooking and BP/hypertension. Indoor solid fuel use is prevalent in China, especially in the rural areas. Its negative impact on BP suggested that modernization of household fuel use may help to reduce the burden of hypertension in China. 相似文献
5.
The Chinese Remainder Theorem (CRT) explains how to estimate an integer-valued number from the knowledge of the remainders obtained by dividing such unknown integer by co-prime integers. As an algebraic theorem, CRT is the basis for several techniques concerning data processing. For instance, considering a single-tone signal whose frequency value is above the sampling rate, the respective peak in the DFT informs the impinging frequency value modulo the sampling rate. CRT is nevertheless sensitive to errors in the remainders, and many efforts have been developed in order to improve its robustness. In this paper, we propose a technique to estimate real-valued numbers by means of CRT, employing for this goal a Kroenecker based M-Estimation (ME), specially suitable for CRT systems with low number of remainders. Since ME schemes are in general computationally expensive, we propose a mapping vector obtained via Kroenecker products which considerably reduces the computational complexity. Furthermore, our proposed technique enhances the probability of estimating an unknown number accurately even when the errors in the remainders surpass 1/4 of the greatest common divisor of all moduli. We also provide a version of the mapping vectors based on tensorial n-mode products, delivering in the end the same information of the original method. Our approach outperforms the state-of-the-art CRT methods not only in terms of percentage of successful estimations but also in terms of smaller average error. 相似文献
6.
针对煤矿发生事故后传统救援监控系统无法实时对井下人员进行动态定位,导致矿井救援盲目性大、救援效率差、救援难度大等技术难题,为了进一步提高煤矿救援效率,通过技术研究,设计了一套以通信基站为核心的智能化救援监控系统,分析了该系统结构组成、工作原理,通过在担水沟煤矿井下实际应用效果来看,智能化救援监控系统对人员定位精准度达95%,实现人员动态位置三维成像,救援效率提高至80%以上,有效缩短了煤矿事故救援时间,取得了显著应用成效。 相似文献
7.
Mingzhi Zhao Jianwei Cao Zhi Wang Guohua Li 《Journal of the European Ceramic Society》2019,39(7):2427-2435
The crystallization phenomena of spinel in CaO-MgO-Al2O3-SiO2-Fe2O3 glass have received much attention due to the particular role in preparation of glass-ceramic materials, which represent an effective option to manage hazardous waste. In this study, both preliminary spinel and secondary spinel were precipitated in the precursor glass. The formation of these spinel was meticulously assessed by a combination of X-ray diffractometry and scanning electron microscopy. The structure of the microenvironment in the precursor glass was characterized by Raman spectrums. These advanced techniques highlight the potential for one-step crystallization of the glass. The investigation, which focused on one-step crystallization, demonstrated the growth of pyroxene on spinel accompanying a migration of chromium. The results also show the microstructure of the obtained glass-ceramic was very dependent on the heat-treat temperature. This study not only unambiguously reveals the precipitation mechanisms of spinel but also provides more documentation for one-step crystallization in the glass-ceramics field. 相似文献
8.
9.
针对基于规则和统计的传统中文简历解析方法效率低、成本高、泛化能力差的缺点,提出一种基于特征融合的中文简历解析方法,即级联Word2Vec生成的词向量和用BLSTM(Bidirectional Long Short-Term Memory)建模字序列生成的词向量,然后再结合BLSTM和CRF(Conditional Random Fields)对中文简历进行解析(BLSTM-CRF)。为了提高中文简历解析的效率,级联包含字序列信息的词向量和用Word2Vec生成的词向量,融合成一个新的词向量表示;再由BLSTM强大的学习能力融合词的上下文信息,输出所有可能标签序列的分值给CRF层;再由CRF引入标签之间约束关系求解最优序列。利用梯度下降算法训练神经网络,使用预先训练的词向量和Dropout优化神经网络,最终完成对中文简历的解析工作。实验结果表明,所提的特征融合方法优于传统的简历解析方法。 相似文献
10.
目前,基于因素空间理论的背景基提取算法计算过程复杂,初始化必须依赖各因素极值,基点数量提取冗余等原因,未能在应用中取得很好效果。为此,结合内点判别法和知识可继承、可扩展的思想,提出一种计算简单、初始化独立、基点数量小的改进的背景基提取算法。然后,利用改进的背景基提取算法构造出一种全新的数据分类算法-基点分类算法,基点分类算法以提取每一类样本的背景基为预测模型,再通过新定义的λ-背景基,优化预测模型。数值实验表明:基点分类算法原理简单、构造难度小、分类模型泛化能力强,预测能力准确率高,同时严格的模型限定区域又能为识别新类别提供新方法。 相似文献