全文获取类型
收费全文 | 5148篇 |
免费 | 261篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 73篇 |
综合类 | 18篇 |
化学工业 | 955篇 |
金属工艺 | 102篇 |
机械仪表 | 90篇 |
建筑科学 | 184篇 |
矿业工程 | 14篇 |
能源动力 | 208篇 |
轻工业 | 231篇 |
水利工程 | 25篇 |
石油天然气 | 24篇 |
无线电 | 453篇 |
一般工业技术 | 937篇 |
冶金工业 | 1154篇 |
原子能技术 | 32篇 |
自动化技术 | 924篇 |
出版年
2023年 | 72篇 |
2022年 | 44篇 |
2021年 | 174篇 |
2020年 | 133篇 |
2019年 | 132篇 |
2018年 | 139篇 |
2017年 | 152篇 |
2016年 | 150篇 |
2015年 | 128篇 |
2014年 | 205篇 |
2013年 | 267篇 |
2012年 | 270篇 |
2011年 | 285篇 |
2010年 | 199篇 |
2009年 | 203篇 |
2008年 | 198篇 |
2007年 | 174篇 |
2006年 | 152篇 |
2005年 | 100篇 |
2004年 | 102篇 |
2003年 | 104篇 |
2002年 | 72篇 |
2001年 | 76篇 |
2000年 | 64篇 |
1999年 | 78篇 |
1998年 | 277篇 |
1997年 | 167篇 |
1996年 | 150篇 |
1995年 | 111篇 |
1994年 | 100篇 |
1993年 | 76篇 |
1992年 | 44篇 |
1991年 | 54篇 |
1990年 | 56篇 |
1989年 | 46篇 |
1988年 | 48篇 |
1987年 | 40篇 |
1986年 | 28篇 |
1985年 | 54篇 |
1984年 | 37篇 |
1983年 | 28篇 |
1982年 | 34篇 |
1981年 | 34篇 |
1979年 | 25篇 |
1978年 | 26篇 |
1977年 | 44篇 |
1976年 | 53篇 |
1974年 | 25篇 |
1973年 | 21篇 |
1972年 | 21篇 |
排序方式: 共有5424条查询结果,搜索用时 31 毫秒
1.
Forster Yannick Hergeth Sebastian Naujoks Frederik Krems Josef F. Keinath Andreas 《Cognition, Technology & Work》2020,22(4):703-720
Cognition, Technology & Work - For a successful market introduction of Level 3 Automated Driving Systems (L3 ADS), a careful evaluation of human–machine interfaces (HMIs) is necessary.... 相似文献
2.
Networks and Spatial Economics - A new comparative framework for estimating the road access of airports around the world at high resolution is proposed. While existing studies are spatially... 相似文献
3.
Richard Demmler Janis Fricke Sebastian Dörner Dr. Markus Gressler Prof. Dr. Dirk Hoffmeister 《Chembiochem : a European journal of chemical biology》2020,21(9):1364-1371
Psychotropic Psilocybe mushrooms biosynthesize their principal natural product psilocybin in five steps, among them a phosphotransfer and two methyltransfer reactions, which consume one equivalent of 5′-adenosine triphosphate (ATP) and two equivalents of S-adenosyl-l -methionine (SAM). This short but co-substrate-intensive pathway requires nucleoside cofactor salvage to maintain high psilocybin production rates. We characterized the adenosine kinase (AdoK) and S-adenosyl-l -homocysteine (SAH) hydrolase (SahH) of Psilocybe cubensis. Both enzymes are directly or indirectly involved in regenerating SAM. qRT-PCR expression analysis revealed an induced expression of the genes in the fungal primordia and carpophores. A one-pot in vitro reaction with the N-methyltransferase PsiM of the psilocybin pathway demonstrates a concerted action with SahH to facilitate biosynthesis by removal of accumulating SAH. 相似文献
4.
Sebastian Biba 《国际水》2018,43(5):622-641
This article analyzes China’s Mekong River politics before and after the establishment of the Lancang-Mekong Cooperation (LMC) from a comparative benefit-sharing perspective. China’s pre-LMC approach focused too much on the creation of economic benefits from and beyond the river while neglecting ecological benefits to the river. Moreover, despite the problems this ‘old’ approach caused for China and its downstream neighbours, China’s current LMC strategy seems to essentially replicate its former approach. While sustainable water resources management is identified as a priority area, actual cooperation and benefit sharing in this field remain insufficient. 相似文献
5.
6.
Xiao Junbing Yan Hongjie Liu Liu Möller Felix Hu Zhiwen Unger Sebastian 《Metallurgical and Materials Transactions B》2019,50(6):3002-3011
Metallurgical and Materials Transactions B - Spout height is a widely used parameter to quantitatively analyze the performance of the submerged gas injection in industrial applications. However,... 相似文献
7.
Kihong Lee Sebastian F. Maehrlein Xinjue Zhong Daniele Meggiolaro Jake C. Russell Douglas A. Reed Bonnie Choi Filippo De Angelis Xavier Roy Xiaoyang Zhu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(36)
The coupling of phonons to electrons and other phonons plays a defining role in material properties, such as charge and energy transport, light emission, and superconductivity. In atomic solids, phonons are delocalized over the 3D lattice, in contrast to molecular solids where localized vibrations dominate. Here, a hierarchical semiconductor that expands the phonon space by combining localized 0D modes with delocalized 2D and 3D modes is described. This material consists of superatomic building blocks (Re6Se8) covalently linked into 2D sheets that are stacked into a layered van der Waals lattice. Using transient reflectance spectroscopy, three types of coherent phonons are identified: localized 0D breathing modes of isolated superatom, 2D synchronized twisting of superatoms in layers, and 3D acoustic interlayer deformation. These phonons are coupled to the electronic degrees of freedom to varying extents. The presence of local phonon modes in an extended crystal opens the door to controlling material properties from hierarchical phonon engineering. 相似文献
8.
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
9.
10.
Sebastian Roth Peter Stockinger Jakob Steff Simon Steimle Dr. Viktor Sautner Prof. Dr. Kai Tittmann Prof. Dr. Jürgen Pleiss Prof. Dr. Michael Müller 《Chembiochem : a European journal of chemical biology》2020,21(18):2615-2619
The family of NAD(P)H-dependent short-chain dehydrogenases/reductases (SDRs) comprises numerous biocatalysts capable of C=O or C=C reduction. The highly homologous noroxomaritidine reductase (NR) from Narcissus sp. aff. pseudonarcissus and Zt_SDR from Zephyranthes treatiae, however, are SDRs with an extended imine substrate scope. Comparison with a similar SDR from Asparagus officinalis (Ao_SDR) exhibiting keto-reducing activity, yet negligible imine-reducing capability, and mining the Short-Chain Dehydrogenase/Reductase Engineering Database indicated that NR and Zt_SDR possess a unique active-site composition among SDRs. Adapting the active site of Ao_SDR accordingly improved its imine-reducing capability. By applying the same strategy, an unrelated SDR from Methylobacterium sp. 77 (M77_SDR) with distinct keto-reducing activity was engineered into a promiscuous enzyme with imine-reducing activity, thereby confirming that the ability to reduce imines can be rationally introduced into members of the “classical” SDR enzyme family. Thus, members of the SDR family could be a promising starting point for protein approaches to generate new imine-reducing enzymes. 相似文献