全文获取类型
收费全文 | 1079618篇 |
免费 | 82432篇 |
国内免费 | 48606篇 |
专业分类
电工技术 | 44805篇 |
技术理论 | 1篇 |
综合类 | 22346篇 |
化学工业 | 160436篇 |
金属工艺 | 58633篇 |
机械仪表 | 34293篇 |
建筑科学 | 34215篇 |
矿业工程 | 18456篇 |
能源动力 | 32422篇 |
轻工业 | 96670篇 |
水利工程 | 17025篇 |
石油天然气 | 30391篇 |
武器工业 | 3725篇 |
无线电 | 133930篇 |
一般工业技术 | 204607篇 |
冶金工业 | 170849篇 |
原子能技术 | 20416篇 |
自动化技术 | 127436篇 |
出版年
2022年 | 9797篇 |
2021年 | 13853篇 |
2020年 | 14949篇 |
2019年 | 25771篇 |
2018年 | 32398篇 |
2017年 | 34057篇 |
2016年 | 34548篇 |
2015年 | 28605篇 |
2014年 | 33416篇 |
2013年 | 59522篇 |
2012年 | 40436篇 |
2011年 | 45594篇 |
2010年 | 37628篇 |
2009年 | 37731篇 |
2008年 | 36783篇 |
2007年 | 35904篇 |
2006年 | 31439篇 |
2005年 | 28581篇 |
2004年 | 30239篇 |
2003年 | 28585篇 |
2002年 | 27065篇 |
2001年 | 26229篇 |
2000年 | 24352篇 |
1999年 | 25221篇 |
1998年 | 54373篇 |
1997年 | 39284篇 |
1996年 | 31042篇 |
1995年 | 24251篇 |
1994年 | 21552篇 |
1993年 | 20978篇 |
1992年 | 16060篇 |
1991年 | 14867篇 |
1990年 | 14268篇 |
1989年 | 13639篇 |
1988年 | 12912篇 |
1987年 | 10880篇 |
1986年 | 10589篇 |
1985年 | 12017篇 |
1984年 | 10848篇 |
1983年 | 10333篇 |
1982年 | 9395篇 |
1981年 | 9542篇 |
1980年 | 9048篇 |
1979年 | 8816篇 |
1978年 | 8487篇 |
1977年 | 9711篇 |
1976年 | 12641篇 |
1975年 | 7546篇 |
1974年 | 7176篇 |
1973年 | 7232篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
81.
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
82.
Romero-Garcés A. Salles De Freitas R. Marfil R. Vicente-Chicote C. Martínez J. Inglés-Romero J. F. Bandera A. 《Multimedia Tools and Applications》2022,81(3):3603-3628
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,... 相似文献
83.
Belov M. I. Anashin D. V. Kabdin N. E. Storchevoy V. F. Sudnik Yu. A. 《Russian Engineering Research》2022,42(11):1110-1116
Russian Engineering Research - The stability of robot-mower motion in a specific direction is considered. The direction is regulated by means of an angular sensor and a programmable controller... 相似文献
84.
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
85.
针对目前集成电路版图分析与设计课程存在教学方法老化、教学模式形式化等问题,本文以OBE-CDIO教育理念为指导,对”集成电路版图分析与设计”课程的课程教学模式、课程设计、项目式教学方式和课程考核方式等方面的改革进行有益的探索与实践。将工程教学认证中对学生的专业毕业要求作为制定教学目标的依据,将BB网络平台、ISO9001等现代化教学资源和质量标准融入课堂教学,采用OBE-CDIO能力教学理念指导课程设计,实现教学环节与考核环节的科学化与多元化,通过引入课程思政激发学生学习热情,树立社会主义核心价值观,全面地培养学生的综合版图分析与设计能力和素养。 相似文献
86.
Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献
87.
Mohammed Amin Salih Venkatachalam K. Hubálovský S. Trojovský P. Prabu P. 《Mobile Networks and Applications》2022,27(3):1050-1059
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via... 相似文献
88.
Yuan-Cheng Meng Hua-Feng Zhang Xiao-Xiao Pan Nan Chen Hui-Fang Hu Saeed ul Haq Abid Khan Ru-Gang Chen 《International journal of molecular sciences》2021,22(6)
Dehydrins (DHNs) play an important role in abiotic stress tolerance in a large number of plants, but very little is known about the function of DHNs in pepper plants. Here, we isolated a Y1SK2-type DHN gene “CaDHN3” from pepper. To authenticate the function of CaDHN3 in salt and drought stresses, it was overexpressed in Arabidopsis and silenced in pepper through virus-induced gene silencing (VIGS). Sub-cellular localization showed that CaDHN3 was located in the nucleus and cell membrane. It was found that CaDHN3-overexpressed (OE) in Arabidopsis plants showed salt and drought tolerance phenotypic characteristics, i.e., increased the initial rooting length and germination rate, enhanced chlorophyll content, lowered the relative electrolyte leakage (REL) and malondialdehyde (MDA) content than the wild-type (WT) plants. Moreover, a substantial increase in the activities of antioxidant enzymes; including the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and lower hydrogen peroxide (H2O2) contents and higher O2•− contents in the transgenic Arabidopsis plants. Silencing of CaDHN3 in pepper decreased the salt- and drought-stress tolerance, through a higher REL and MDA content, and there was more accumulation of reactive oxygen species (ROS) in the CaDHN3-silenced pepper plants than the control plants. Based on the yeast two-hybrid (Y2H) screening and Bimolecular Fluorescence Complementation (BiFC) results, we found that CaDHN3 interacts with CaHIRD11 protein in the plasma membrane. Correspondingly, the expressions of four osmotic-related genes were significantly up-regulated in the CaDHN3-overexpressed lines. In brief, our results manifested that CaDHN3 may play an important role in regulating the relative osmotic stress responses in plants through the ROS signaling pathway. The results of this study will provide a basis for further analyses of the function of DHN genes in pepper. 相似文献
89.
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
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