全文获取类型
收费全文 | 123929篇 |
免费 | 12563篇 |
国内免费 | 7295篇 |
专业分类
电工技术 | 9426篇 |
技术理论 | 9篇 |
综合类 | 10007篇 |
化学工业 | 18293篇 |
金属工艺 | 7411篇 |
机械仪表 | 8497篇 |
建筑科学 | 10222篇 |
矿业工程 | 3859篇 |
能源动力 | 3800篇 |
轻工业 | 9400篇 |
水利工程 | 2750篇 |
石油天然气 | 6340篇 |
武器工业 | 1395篇 |
无线电 | 14578篇 |
一般工业技术 | 13192篇 |
冶金工业 | 5225篇 |
原子能技术 | 1629篇 |
自动化技术 | 17754篇 |
出版年
2024年 | 608篇 |
2023年 | 2010篇 |
2022年 | 3776篇 |
2021年 | 5096篇 |
2020年 | 3917篇 |
2019年 | 3103篇 |
2018年 | 3578篇 |
2017年 | 4061篇 |
2016年 | 3689篇 |
2015年 | 5111篇 |
2014年 | 6674篇 |
2013年 | 7608篇 |
2012年 | 8685篇 |
2011年 | 9125篇 |
2010年 | 8269篇 |
2009年 | 8045篇 |
2008年 | 8141篇 |
2007年 | 7521篇 |
2006年 | 7284篇 |
2005年 | 5984篇 |
2004年 | 4597篇 |
2003年 | 4240篇 |
2002年 | 4938篇 |
2001年 | 4179篇 |
2000年 | 2950篇 |
1999年 | 2341篇 |
1998年 | 1604篇 |
1997年 | 1336篇 |
1996年 | 1202篇 |
1995年 | 943篇 |
1994年 | 801篇 |
1993年 | 523篇 |
1992年 | 425篇 |
1991年 | 329篇 |
1990年 | 260篇 |
1989年 | 214篇 |
1988年 | 155篇 |
1987年 | 100篇 |
1986年 | 95篇 |
1985年 | 42篇 |
1984年 | 40篇 |
1983年 | 32篇 |
1982年 | 36篇 |
1981年 | 29篇 |
1980年 | 19篇 |
1979年 | 19篇 |
1978年 | 3篇 |
1976年 | 6篇 |
1959年 | 19篇 |
1951年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
This paper considers a novel distributed iterative learning consensus control algorithm based on neural networks for the control of heterogeneous nonlinear multiagent systems. The system's unknown nonlinear function is approximated by suitable neural networks; the approximation error is countered by a robust term in the control. Two types of control algorithms, both of which utilize distributed learning laws, are provided to achieve consensus. In the provided control algorithms, the desired reference is considered to be an unknown factor and then estimated using the associated learning laws. The consensus convergence is proven by the composite energy function method. A numerical simulation is ultimately presented to demonstrate the efficacy of the proposed control schemes. 相似文献
52.
Yao Dajie Liu Xiaofei Wu Jian 《International Journal of Control, Automation and Systems》2020,18(9):2251-2258
International Journal of Control, Automation and Systems - In this paper, the tracking problem for a class of uncertain nonlinearly parameterized systems with input delay based the adaptive... 相似文献
53.
针对电牵引采煤机渐开线行走轮在ANSYS分析中存在的问题,提出运用APDL语言命令直接建模,并通过VB与ANSYS的交互运行途径,设计了基于VB界面和程序的软件,实现了利用VB界面直接输入参数并调用ANSYS对行走轮自动建模、加载和计算的有限元分析。验证结果表明,该软件减少了设计人员的重复劳动,提高了行走轮的设计效率和水平,具有一定的工程实用价值。 相似文献
54.
55.
The red grape berry pigments, anthocyanins, were characterized in the early 20th century, but investigations of wine pigments were stymied during that era. The question of their identity was a major challenge for wine chemists. A number of techniques showed that the pigments were polymeric in nature. Some structures were postulated by mid-century based on reactions between anthocyanins and condensed tannin, and later postulated wine pigments were observed in model reactions. Some related compounds were then observed in wine. By the end of the 20th century, the ionization of non-volatiles for mass spectrometry opened the door to these compounds. In addition, a new class of compounds was observed, the pyranoanthocyanins, a product of fermentation and aging metabolites with anthocyanins. These compounds possess the pigment stability to SO2 and pH change that is characteristic of aged red wine. Aging experiments show a dynamic situation with shifts in the population of pigment classes over time. The very large number of diverse pigments explains why it has been so difficult to answer the century-old question of the structure of wine pigments. Our current understanding is founded on the use of mass spectral analysis using electrospray and related ionization techniques over the last 25 years. Future progress will rely on more sophisticated analysis of this very complex mixture of substances. © 2019 Society of Chemical Industry 相似文献
56.
57.
Sowoon Seo Yunjeong Song Sun Mi Gu Hyun Kyu Min Jin Tae Hong Hye Jin Cha Jaesuk Yun 《International journal of molecular sciences》2020,21(23)
Background: Epilepsy is a chronic neurological disorder characterized by the recurrence of seizures. One-third of patients with epilepsy may not respond to antiseizure drugs. Purpose: We aimed to examine whether D-limonene, a cyclic monoterpene, exhibited any antiseizure activity in the pentylenetetrazole (PTZ)-induced kindling mouse model and in vitro. Methods: PTZ kindling mouse model was established by administering PTZ (30 mg/kg) intraperitoneally to mice once every 48 h. We performed immunoblot blots, immunohistochemistry (IHC), and high-performance liquid chromatography (HPLC) analysis after the behavioral study. Results: An acute injection of PTZ (60 mg/kg) induced seizure in mice, while pretreatment with D-limonene inhibited PTZ-induced seizure. Repeated administration of PTZ (30 mg/kg) increased the seizure score gradually in mice, which was reduced in D-limonene (10 mg/kg)-pretreated group. In addition, D-limonene treatment increased glutamate decarboxylase-67 (GAD-67) expression in the hippocampus. Axonal sprouting of hippocampal neurons after kindling was inhibited by D-limonene pretreatment. Moreover, D-limonene reduced the expression levels of Neuronal PAS Domain Protein 4 (Npas4)-induced by PTZ. Furthermore, the adenosine A2A antagonist and ZM241385 inhibited anticonvulsant activity and gamma-aminobutyric acid (GABA)ergic neurotransmission-induced by D-limonene. Conclusion: These results suggest that D-limonene exhibits anticonvulsant activity through modulation of adenosine A2A receptors on GABAergic neuronal function. SCH58261相似文献
58.
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
59.
60.
Xueliang Wang Huiqin Yin Wenguan Liu Guojun Yu Jian He Zhongfeng Tang Long Yan 《工业材料与腐蚀》2020,71(6):931-937
Understanding the corrosion of molten ZnCl2 on metal surfaces is significant for the corrosion protection of metals, sustainable use of molten salts, preparation of ZnO coatings, and so on. In this paper, surfaces of pure Ni, Cr, and Fe corroded by molten ZnCl2 were investigated. The results show that Ni suffered very slight corrosion, while Cr experienced more serious corrosion than Ni, but lighter corrosion than Fe. The morphology of the corrosion of Cr and Fe, respectively, presented pitting and intergranular corrosion characteristics. Furthermore, nanostructured ZnO coatings were obtained on the surfaces of Ni and Fe, but not on the surface of Cr. The ZnO coating on the Ni surface was doped with a small amount of Zn5(OH)8Cl2, and the ZnO coating on the Fe surface was doped with ZnFe2O4 and Zn2OCl2. The coatings on the Ni and Fe surfaces had an average thickness of 1.5 and 50 μm, respectively. 相似文献