全文获取类型
收费全文 | 559篇 |
免费 | 32篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 148篇 |
金属工艺 | 18篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
能源动力 | 29篇 |
轻工业 | 41篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 77篇 |
一般工业技术 | 138篇 |
冶金工业 | 71篇 |
原子能技术 | 6篇 |
自动化技术 | 46篇 |
出版年
2023年 | 6篇 |
2022年 | 23篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 27篇 |
2017年 | 18篇 |
2016年 | 23篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 34篇 |
2012年 | 30篇 |
2011年 | 19篇 |
2010年 | 35篇 |
2009年 | 23篇 |
2008年 | 27篇 |
2007年 | 16篇 |
2006年 | 14篇 |
2005年 | 20篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 20篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
排序方式: 共有595条查询结果,搜索用时 15 毫秒
1.
Prof. Andrea Baier Dr. Anne Kokel Dr. William Horton Ewa Gizińska Dr. Garima Pandey Prof. Ryszard Szyszka Prof. Béla Török Prof. Marianna Török 《ChemMedChem》2021,16(12):1927-1932
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays. 相似文献
2.
Diffusional limitations (the gel, glass, and cage effects) are manifested in several bulk free radical homopolymerizations as well as in random copolymerizations. These are associated with decreases of several orders of magnitude of the rate constants of termination, propagation, and initiation (the initiator efficiency), respectively. These phenomena have been modeled earlier using the free volume theory for the diffusivities of primary radicals, macro‐radicals, and monomer molecules, and have been applied to homopolymerizations. In this study, a similar model is developed for random bulk copolymerizations. The parameters of the model are fitted using isothermal data on styrene acrylonitrile random copolymerization carried out in small ampoules. Thereafter, best‐fit global correlations have been developed for this system. This enables the model to be used for studying non‐isothermal copolymerizations, as well as for carrying out optimization of industrial reactors, where non‐isothermal conditions are a norm. POLYM. ENG. SCI., 55:2098–2110, 2015. © 2014 Society of Plastics Engineers 相似文献
3.
The bulk copolymerization of styrene–acrylonitrile monomers using styrene‐N+–montmorillonite complex as a comonomer in the polymerization was studied. The X‐ray diffraction (XRD) analysis showed that part of the styrene‐N+–montmorillonite complex remained non‐dispersed (immiscible) and the copolymer was excluded from the interlayer of the immiscible part of the clay. The successive chemical extraction process revealed that a reasonable amount of the styrene–acrylonitrile copolymer was directly attached to the styrene‐N+–montmorillonite complex and enveloped the clay. Highly exfoliated clay lamella and nanospheres (3–5 nm) were observed by transmission electron microscopy (TEM). The montmorillonite clay assume two different morphologies, immiscible and exfoliated, on the basis of the XRD and TEM data. A simple method of calculation of the ratio of the exfoliated/immiscible amounts of the clay indicated that the amount of the styrene‐N+–montmorillonite complex exfoliated into separate lamella was 40 % (w/w) of the amount of the clay samples containing 2 % of the (styrene‐N+–montmorillonite complex) clay. This amount of exfoliated clay decreases with the increase of the concentration of the clay. The presence of the styrene‐N+–montmorillonite clay in the copolymerization reaction had a minor effect on both the copolymer composition and the molecular weight. Modification of the clay with the derivatized styrene monomer can achieve a nanocomposite using a percentage no more than 4 % (w/w) of complex in the copolymer. Copyright © 2004 Society of Chemical Industry 相似文献
4.
S. Vaidyanathan K. M. Kavadia L. P. Borkar S. P. Mahajan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(2):121-128
With a view to evaluate the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth, experiments were conducted in a 160 dm3 capacity, well-mixed continuous digestion unit at ambient temperature. The optimal design of biogas plant using water hyacinth was elucidated, to provide a unit giving a maximum methane yield of 0.16 nm3 kg?1 volatile solids added, which was 60% greater than the conventional plant using cowdung. The calculations of optimal design factors were based on reactor size, hydraulic retention time and volatile solids loading rate; considerations were made of capital cost, running costs and operational revenue. 相似文献
5.
Garimella S.V. Joshi Y.K. Bar-Cohen A. Mahajan R. Toh K.C. Carey V.P. Baelmans M. Lohan J. Sammakia B. Andros F. 《Components and Packaging Technologies, IEEE Transactions on》2002,25(4):569-575
The presentations made, as well as the discussions, in the panels at the workshop, Thermal Challenges in Next Generation Electronic Systems (THERMES), are summarized in this paper. The panels dealt with diverse topics including thermal management roadmaps, microscale cooling systems, numerical modeling from the component to system levels, hardware for future high performance and Internet computing architectures, and transport issues in the manufacturing of electronic packages. The focus of the panels was to identify barriers to further progress in each area that require the attention of the research community. 相似文献
6.
Garima Lakhanpal Jay R. Black Roser Casas-Mulet Meenakshi Arora Michael J. Stewardson 《河流研究与利用》2023,39(4):734-744
Fine particle clogging and faunal bioturbation are two key processes co-occurring in the hyporheic zone that potentially affect hyporheic exchange through modifications in the sediment structure of streambeds. Clogging results from excessive fine sediment infiltration and deposition in rivers, and it is known to decrease matrix porosity and potentially reduce permeability. Faunal bioturbation activity may compensate for the negative effect of clogging by reworking the sediment, increasing porosity, and preventing further infiltration of fines. Although both processes of clogging and bioturbation have received significant attention in the literature separately, their combined effects on streambed sediment structure are not well understood, mostly due to the lack of a standard methodology for their assessment. Here, we illustrate a novel methodology using X-ray computed tomography (CT), as proof of concept, to investigate how, together, clogging and bioturbation affect streambed porosity in a controlled flow-through flume. By visualising gallery formations of an upward conveyor macroinvertebrate; Lumbriculus variegatus as a model species, we quantified bioturbation activity in a clogged streambed, focusing on orientation, depth, and volume at downwelling and upwelling areas of the flume. Gallery creation increased the porosity of the streambed sediment, suggesting a potential improvement in permeability and a possible offset of clogging effects. We illustrate the promising use of X-ray CT as a tool to assess bioturbation in clogged streambeds, and the potential role of bioturbation activity supporting hyporheic exchange processes in streambeds, warranting further studies to understand the extent of bioturbation impacts in natural systems. 相似文献
7.
8.
Mahajan VN 《Applied optics》1994,33(34):8121
Zernike circle polynomials, their numbering scheme, and relationship to balanced optical aberrations of systems with circular pupils are discussed. 相似文献
9.
Mahajan Nitish Chauhan Amita Kumar Harish Kaushal Sakshi Sangaiah Arun Kumar 《Mobile Networks and Applications》2022,27(4):1423-1443
Mobile Networks and Applications - In the era of Internet of Things (IoT) powered by 5G technologies, Automobile Industry is headed towards a revolution. In Intelligent Transport Systems (ITS),... 相似文献
10.
K. Rajakumari M.Vinoth Kumar Garima Verma S. Balu Dilip Kumar Sharma Sudhakar Sengan 《计算机系统科学与工程》2022,40(2):581-592
Cloud computing is an Information Technology deployment model established on virtualization. Task scheduling states the set of rules for task allocations to an exact virtual machine in the cloud computing environment. However, task scheduling challenges such as optimal task scheduling performance solutions, are addressed in cloud computing. First, the cloud computing performance due to task scheduling is improved by proposing a Dynamic Weighted Round-Robin algorithm. This recommended DWRR algorithm improves the task scheduling performance by considering resource competencies, task priorities, and length. Second, a heuristic algorithm called Hybrid Particle Swarm Parallel Ant Colony Optimization is proposed to solve the task execution delay problem in DWRR based task scheduling. In the end, a fuzzy logic system is designed for HPSPACO that expands task scheduling in the cloud environment. A fuzzy method is proposed for the inertia weight update of the PSO and pheromone trails update of the PACO. Thus, the proposed Fuzzy Hybrid Particle Swarm Parallel Ant Colony Optimization on cloud computing achieves improved task scheduling by minimizing the execution and waiting time, system throughput, and maximizing resource utilization. 相似文献