全文获取类型
收费全文 | 1478423篇 |
免费 | 25790篇 |
国内免费 | 6968篇 |
专业分类
电工技术 | 34080篇 |
综合类 | 6390篇 |
化学工业 | 268535篇 |
金属工艺 | 63815篇 |
机械仪表 | 41117篇 |
建筑科学 | 45395篇 |
矿业工程 | 11284篇 |
能源动力 | 50145篇 |
轻工业 | 108140篇 |
水利工程 | 15011篇 |
石油天然气 | 37267篇 |
武器工业 | 131篇 |
无线电 | 195039篇 |
一般工业技术 | 277289篇 |
冶金工业 | 156413篇 |
原子能技术 | 33779篇 |
自动化技术 | 167351篇 |
出版年
2021年 | 15483篇 |
2020年 | 11790篇 |
2019年 | 14538篇 |
2018年 | 14448篇 |
2017年 | 13584篇 |
2016年 | 20633篇 |
2015年 | 17213篇 |
2014年 | 28579篇 |
2013年 | 87631篇 |
2012年 | 34197篇 |
2011年 | 45640篇 |
2010年 | 41218篇 |
2009年 | 49792篇 |
2008年 | 43108篇 |
2007年 | 39975篇 |
2006年 | 43796篇 |
2005年 | 38191篇 |
2004年 | 40702篇 |
2003年 | 40660篇 |
2002年 | 39946篇 |
2001年 | 36738篇 |
2000年 | 35196篇 |
1999年 | 34280篇 |
1998年 | 42497篇 |
1997年 | 37670篇 |
1996年 | 34437篇 |
1995年 | 30197篇 |
1994年 | 28419篇 |
1993年 | 28277篇 |
1992年 | 25968篇 |
1991年 | 23137篇 |
1990年 | 23393篇 |
1989年 | 22505篇 |
1988年 | 21015篇 |
1987年 | 19311篇 |
1986年 | 18645篇 |
1985年 | 22001篇 |
1984年 | 22218篇 |
1983年 | 20197篇 |
1982年 | 19233篇 |
1981年 | 19316篇 |
1980年 | 17923篇 |
1979年 | 18470篇 |
1978年 | 17745篇 |
1977年 | 17531篇 |
1976年 | 18758篇 |
1975年 | 16006篇 |
1974年 | 15516篇 |
1973年 | 15574篇 |
1972年 | 13050篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Wireless Personal Communications - This paper summarizes the ongoing research initiatives based on the advanced multiple access techniques towards the fifth generation (5G) wireless communication... 相似文献
83.
Dr. Ying Wang Prof. Dr. Andrew Ewing 《Chembiochem : a European journal of chemical biology》2021,22(5):807-813
Exocytosis plays an essential role in the communication between cells in the nervous system. Understanding the regulation of neurotransmitter release during exocytosis and the amount of neurotransmitter content that is stored in vesicles is of importance, as it provides fundamental insights to understand how the brain works and how neurons elicit a certain behavior. In this minireview, we summarize recent progress in amperometric measurements for monitoring exocytosis in single cells and electrochemical cytometry measurements of vesicular neurotransmitter content in individual vesicles. Important steps have increased our understanding of the different mechanisms of exocytosis. Increasing evidence is firmly establishing that partial release is the primary mechanism of release in multiple cell types. 相似文献
84.
Liangtao Yang Liang-Yin Kuo Juan Miguel López del Amo Prasant Kumar Nayak Katherine A. Mazzio Sebastian Maletti Daria Mikhailova Lars Giebeler Payam Kaghazchi Teófilo Rojo Philipp Adelhelm 《Advanced functional materials》2021,31(38):2102939
A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na0.67Mn0.6Ni0.2Li0.2O2 is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g-1 after 100 cycles. In contrast, the Li-free compositions Na0.67Mn0.6Ni0.4O2 and Na0.67Mn0.8Ni0.2O2 show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni3+/Ni4+ and O2-/O2-δ redox processes by DFT, although a small contribution from Mn4+/Mn5+ to the capacity cannot be excluded. 相似文献
85.
Revin A. A. Mikhaylova A. M. Konakov A. A. Tsyplenkov V. V. Shastin V. N. 《Semiconductors》2021,55(12):879-884
Semiconductors - The wave functions of electrons localized at P, As, and Sb shallow donors in Ge are calculated in the envelope function approximation taking into account valley–orbit... 相似文献
86.
Alawiya Reslan Juliano G. Haddad Liadrine Moukendza Koundi Philippe Desprs Jean-Loup Bascands Gilles Gadea 《International journal of molecular sciences》2021,22(5)
Mosquito-borne Zika virus (ZIKV) became a real threat to human health due to the lack of vaccine and effective antiviral treatment. The virus has recently been responsible for a global outbreak leading to millions of infected cases. ZIKV complications were highlighted in adults with Guillain–Barré syndrome and in newborns with increasing numbers of congenital disorders ranging from mild developmental delays to fatal conditions. The ability of ZIKV to establish a long-term infection in diverse organs including the kidneys has been recently documented but the consequences of such a viral infection are still debated. Our study aimed to determine whether the efficiency of ZIKV growth in kidney cells relates to glucose concentration. Human kidney HK-2 cells were infected with different ZIKV strains in presence of normal and high glucose concentrations. Virological assays showed a decrease in viral replication without modifying entry steps (viral binding, internalization, fusion) under high glucose conditions. This decrease replication was associated with a lower virus progeny and increased cell viability when compared to ZIKV-infected HK-2 cells in normal glucose concentration. In conclusion, we showed for the first time that an elevated glucose level influences ZIKV replication level with an effect on kidney cell survival. 相似文献
87.
88.
Kruglikov S. S. Zagorskii D. L. Kolesnikov V. A. Doludenko I. M. Bedin S. A. 《Theoretical Foundations of Chemical Engineering》2021,55(5):942-951
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of... 相似文献
89.
Dr. Timo Broese Dr. Peter Ehlers Dr. Peter Langer Dr. Jan von Langermann 《Chembiochem : a European journal of chemical biology》2021,22(23):3314-3318
Fluoro-substituted and heteroaromatic compounds are valuable intermediates for a variety of applications in pharma- and agrochemistry and synthetic chemistry. This study investigates the chemoenzymatic preparation of chiral alcohols bearing a heteroaromatic ring with an increasing degree of fluorination in α-position. Starting from readily available picoline derivatives prochiral α-halogenated acyl moieties were introduced with excellent selectivity and 64–95 % yield. The formed carbonyl group was subsequently reduced to the corresponding alcohols using the alcohol dehydrogenase from Lactobacillus kefir, yielding an enantiomeric excess of 95–>99 % and up to 98 % yield. 相似文献
90.
Vasanthapriya R. Neelakandeswari N. Uthayarani K. Chitra M. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4272-4280
Journal of Inorganic and Organometallic Polymers and Materials - This paper reports the performance of alizarin based SnO2 dye-sensitized solar cells. A novel template assisted method has been... 相似文献