全文获取类型
收费全文 | 858957篇 |
免费 | 24620篇 |
国内免费 | 10086篇 |
专业分类
电工技术 | 22992篇 |
技术理论 | 14篇 |
综合类 | 13688篇 |
化学工业 | 132442篇 |
金属工艺 | 38745篇 |
机械仪表 | 33102篇 |
建筑科学 | 31623篇 |
矿业工程 | 7985篇 |
能源动力 | 22697篇 |
轻工业 | 63269篇 |
水利工程 | 9824篇 |
石油天然气 | 20216篇 |
武器工业 | 1365篇 |
无线电 | 103546篇 |
一般工业技术 | 153988篇 |
冶金工业 | 125902篇 |
原子能技术 | 14219篇 |
自动化技术 | 98046篇 |
出版年
2023年 | 4364篇 |
2022年 | 8933篇 |
2021年 | 12814篇 |
2020年 | 9483篇 |
2019年 | 9758篇 |
2018年 | 26019篇 |
2017年 | 25890篇 |
2016年 | 22958篇 |
2015年 | 13421篇 |
2014年 | 18890篇 |
2013年 | 40136篇 |
2012年 | 29874篇 |
2011年 | 42373篇 |
2010年 | 35073篇 |
2009年 | 34560篇 |
2008年 | 35763篇 |
2007年 | 36102篇 |
2006年 | 27988篇 |
2005年 | 26112篇 |
2004年 | 22138篇 |
2003年 | 21391篇 |
2002年 | 19870篇 |
2001年 | 18882篇 |
2000年 | 18123篇 |
1999年 | 19673篇 |
1998年 | 41168篇 |
1997年 | 29340篇 |
1996年 | 23314篇 |
1995年 | 17740篇 |
1994年 | 15462篇 |
1993年 | 14842篇 |
1992年 | 10811篇 |
1991年 | 10050篇 |
1990年 | 9447篇 |
1989年 | 8916篇 |
1988年 | 8452篇 |
1987年 | 7305篇 |
1986年 | 7063篇 |
1985年 | 7939篇 |
1984年 | 7160篇 |
1983年 | 6449篇 |
1982年 | 5990篇 |
1981年 | 6085篇 |
1980年 | 5661篇 |
1979年 | 5395篇 |
1978年 | 5322篇 |
1977年 | 6281篇 |
1976年 | 8612篇 |
1975年 | 4552篇 |
1973年 | 4335篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Andrade R. G. S. A. de Oliveira A. E. Guerra V. G. 《Theoretical Foundations of Chemical Engineering》2022,56(4):504-512
Theoretical Foundations of Chemical Engineering - The corona onset voltage is an important operating parameter in the electrostatic precipitation of nanoparticulate, however, its experimental... 相似文献
102.
Wireless Networks - TCP latency is critical to the performance of Web services. However, packet loss greatly impairs the TCP performance due to its poor loss recovery mechanisms. Recent work FUSO... 相似文献
103.
Moustapha Moussa Amudhan Ponrajan Osvaldo H. Campanella Martin R. Okos Mario M. Martinez Bruce R. Hamaker 《International Journal of Food Science & Technology》2022,57(7):4594-4601
Traditional West African pearl millet couscous products are popular; however, their preparation is laborious, time-consuming and energy-demanding, involving agglomeration, steaming, drying and sieving steps. In this study, a process was developed to produce millet couscous using a high pressure, high temperature and low-cost single-screw extruder. The innovation was to directly process the cooked low-moisture extrudate to a couscous product by drying and milling to the appropriate particle size (ranging between 1 and 2 mm). Throughput for the traditional process as prepared for commercial sale is 50 kg per day, but with the same amount of labour, the extrusion process yields ~350 kg per day. A consumer sensory study held in Niamey (Niger) showed that the extruded millet couscous was comparable to traditional couscous, though this was dependent on selection of the proper millet variety. This novel extrusion process could stimulate small- to medium-scale manufacturing of couscous and couscous-type products in West Africa. 相似文献
104.
A. Kathalingam S. Valanarasu Tansir Ahamad Saad M. Alshehri Hyun-Seok Kim 《Ceramics International》2021,47(6):7608-7616
Herein, we report the photosensing property of CdS thin films. CdS thin films were coated onto glass substrates via a spray pyrolysis method using different spray pressures. Prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical and photoluminescence spectroscopy. XRD analysis demonstrated the growth of crystalline CdS films with crystallite sizes varying from 26 to 29 nm depending on the pressure. The SEM and EDAX analyses revealed nearly-stoichiometric CdS films with smooth surfaces and slight variation in grain morphology due to pressure changes. Optical measurements showed a direct bandgap varying from 2.37 eV to 2.42 eV due to pressure changes. A photodetector was also fabricated using the grown CdS films; the fabricated photodetector exhibited good performance depending on the spray pressure. A spray pressure of 1.5 GPa resulted in high photoresponsivity and external quantum efficiency. 相似文献
105.
Cheng-Chin Huang Ching-Yao Yang Chin-Chuan Su Kai-Min Fang Cheng-Chieh Yen Ching-Ting Lin Jui-Min Liu Kuan-I Lee Ya-Wen Chen Shing-Hwa Liu Chun-Fa Huang 《International journal of molecular sciences》2021,22(9)
4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a major active metabolite of bisphenol A (BPA), is generated in the mammalian liver. Some studies have suggested that MBP exerts greater toxicity than BPA. However, the mechanism underlying MBP-induced pancreatic β-cell cytotoxicity remains largely unclear. This study demonstrated the cytotoxicity of MBP in pancreatic β-cells and elucidated the cellular mechanism involved in MBP-induced β-cell death. Our results showed that MBP exposure significantly reduced cell viability, caused insulin secretion dysfunction, and induced apoptotic events including increased caspase-3 activity and the expression of active forms of caspase-3/-7/-9 and PARP protein. In addition, MBP triggered endoplasmic reticulum (ER) stress, as indicated by the upregulation of GRP 78, CHOP, and cleaved caspase-12 proteins. Pretreatment with 4-phenylbutyric acid (4-PBA; a pharmacological inhibitor of ER stress) markedly reversed MBP-induced ER stress and apoptosis-related signals. Furthermore, exposure to MBP significantly induced the protein phosphorylation of JNK and AMP-activated protein kinase (AMPK)α. Pretreatment of β-cells with pharmacological inhibitors for JNK (SP600125) and AMPK (compound C), respectively, effectively abrogated the MBP-induced apoptosis-related signals. Both JNK and AMPK inhibitors also suppressed the MBP-induced activation of JNK and AMPKα and of each other. In conclusion, these findings suggest that MBP exposure exerts cytotoxicity on β-cells via the interdependent activation of JNK and AMPKα, which regulates the downstream apoptotic signaling pathway. 相似文献
106.
107.
This article proposes an active balancer, which features bidirectional charge shuttling and adaptive equalization current control, to fast counterbalance the state of charge (SOC) of cells in a lithium-ion battery (LIB) string. The power circuit consists of certain bidirectional buck-boost converters to transfer energy among the different cells back and forth. Owing to the characterization of the open-circuit voltage (OCV) vs SOC in LIB being relatively smooth near the SOC middle range, the SOC-inspected balance strategy can achieve more precise and efficient equilibrium than the voltage-based control. Accordingly, a compensated OCV-based SOC estimation is put forward to take into account the discrepancy of SOC estimation. Besides, the varied-duty-cycle (VDC) and curve-fitting modulation (CFM) methods are devised herein to tackle the problems of slow equalization rate and low balance efficacy, which arise from the diminution in balancing current as the SOC difference between the cells decreases in the later duration of equalization especially. The proposed strategies have taken the battery nonlinear characteristic and circuit parameter nonideality into account and can adaptively modulate the duty cycle with the SOC difference to keep balancing current constant throughout the balancing cycle. Simulated and experimental results are given to demonstrate the feasibility and effectiveness of the same prototype constructed. Compared with the fixed duty cycle and the VDC methods, the proposed CFM has the best balancing efficiency of 81.4%, and the balance time is shortened by 27.1% and 18.6%, respectively. 相似文献
108.
全球炼化工程总承包市场呈现出垄断竞争型特征,欧美和日韩国际工程公司由于技术和报价竞争力较强,一直占据本行业高端市场,中国炼化工程企业尚有差距.文章综合考虑投标报价阶段竞争者分析路径,提出了随机型和不完全信息静态博弈综合集成分析的投标报价最优决策模型,并以中东海湾地区某炼化工程总承包项目为例,进行多维度的实证分析,提出模型的有效性和可行性,为中国炼化工程企业"走出去"高质量发展提供有益的决策支持和信息参考. 相似文献
109.
Golubev N. V. Ignat’eva E. S. Maurus A. A. Ziyatdinova M. Z. Lopatina E. V. Lorenzi R. Paleari A. Sigaev V. N. 《Glass and Ceramics》2021,77(11-12):415-418
Glass and Ceramics - The influence of Al2O3 as an additive and the heat-treatment regime on the luminescence spectra of gallate glass-ceramics was investigated. It is shown that its luminescence... 相似文献
110.
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