全文获取类型
收费全文 | 1295篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 167篇 |
金属工艺 | 14篇 |
机械仪表 | 30篇 |
建筑科学 | 72篇 |
矿业工程 | 6篇 |
能源动力 | 52篇 |
轻工业 | 86篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
无线电 | 112篇 |
一般工业技术 | 241篇 |
冶金工业 | 394篇 |
原子能技术 | 14篇 |
自动化技术 | 123篇 |
出版年
2023年 | 9篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 25篇 |
2017年 | 28篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 25篇 |
2013年 | 57篇 |
2012年 | 38篇 |
2011年 | 51篇 |
2010年 | 49篇 |
2009年 | 49篇 |
2008年 | 59篇 |
2007年 | 50篇 |
2006年 | 38篇 |
2005年 | 41篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 29篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 27篇 |
1998年 | 99篇 |
1997年 | 58篇 |
1996年 | 51篇 |
1995年 | 23篇 |
1994年 | 28篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 17篇 |
1976年 | 19篇 |
1975年 | 13篇 |
1974年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有1329条查询结果,搜索用时 15 毫秒
1.
2.
Shaikh Rahamatullah Shirazian Saeed Walker Gavin M. 《Neural computing & applications》2021,33(19):12621-12640
Neural Computing and Applications - Milling by mechanical means is vital unit operation in pharmaceutical processing which can be used for controlling particle size reduction. This approach can be... 相似文献
3.
4.
Daniel Boon Loong Teh Akshaya Bansal Chou Chai Tan Boon Toh Robert Alan Jappy Tucker Gil Gerald Lasam Gammad Yanzhuang Yeo Zhendong Lei Xiang Zheng Fengyuan Yang John S. Ho Nagarjun Bolem Bing Cheng Wu Muthu Kumar Gnanasammandhan Lissa Hooi Gavin Stewart Dawe Camilo Libedinsky Wei-Yi Ong Barry Halliwell Edward Kai-Hua Chow Kah-Leong Lim Yong Zhang Brian K. Kennedy 《Advanced materials (Deerfield Beach, Fla.)》2020,32(29):2001459
Near-infrared (NIR) activatable upconversion nanoparticles (UCNPs) enable wireless-based phototherapies by converting deep-tissue-penetrating NIR to visible light. UCNPs are therefore ideal as wireless transducers for photodynamic therapy (PDT) of deep-sited tumors. However, the retention of unsequestered UCNPs in tissue with minimal options for removal limits their clinical translation. To address this shortcoming, biocompatible UCNPs implants are developed to deliver upconversion photonic properties in a flexible, optical guide design. To enhance its translatability, the UCNPs implant is constructed with an FDA-approved poly(ethylene glycol) diacrylate (PEGDA) core clad with fluorinated ethylene propylene (FEP). The emission spectrum of the UCNPs implant can be tuned to overlap with the absorption spectra of the clinically relevant photosensitizer, 5-aminolevulinic acid (5-ALA). The UCNPs implant can wirelessly transmit upconverted visible light till 8 cm in length and in a bendable manner even when implanted underneath the skin or scalp. With this system, it is demonstrated that NIR-based chronic PDT is achievable in an untethered and noninvasive manner in a mouse xenograft glioblastoma multiforme (GBM) model. It is postulated that such encapsulated UCNPs implants represent a translational shift for wireless deep-tissue phototherapy by enabling sequestration of UCNPs without compromising wireless deep-tissue light delivery. 相似文献
5.
Dr. Sean Lund Taylor Courtney Dr. Gavin J. Williams 《Chembiochem : a European journal of chemical biology》2019,20(17):2217-2221
Isoprenoids are a large class of natural products with wide-ranging applications. Synthetic biology approaches to the manufacture of isoprenoids and their new-to-nature derivatives are limited due to the provision in nature of just two hemiterpene building blocks for isoprenoid biosynthesis. To address this limitation, artificial chemo-enzymatic pathways such as the alcohol-dependent hemiterpene (ADH) pathway serve to leverage consecutive kinases to convert exogenous alcohols into pyrophosphates that could be coupled to downstream isoprenoid biosynthesis. To be successful, each kinase in this pathway should be permissive of a broad range of substrates. For the first time, we have probed the promiscuity of the second enzyme in the ADH pathway—isopentenyl phosphate kinase from Thermoplasma acidophilum—towards a broad range of acceptor monophosphates. Subsequently, we evaluate the suitability of this enzyme to provide unnatural pyrophosphates and provide a critical first step in characterizing the rate-limiting steps in the artificial ADH pathway. 相似文献
6.
Ryan M. Williams Cassandra L. Crihfield Srikanth Gattu Lisa A. Holland Letha J. Sooter 《International journal of molecular sciences》2014,15(8):14332-14347
Widespread use of the chlorotriazine herbicide, atrazine, has led to serious environmental and human health consequences. Current methods of detecting atrazine contamination are neither rapid nor cost-effective. In this work, atrazine-specific single-stranded DNA (ssDNA) molecular recognition elements (MRE) were isolated. We utilized a stringent Systematic Evolution of Ligands by Exponential Enrichment (SELEX) methodology that placed the greatest emphasis on what the MRE should not bind to. After twelve rounds of SELEX, an atrazine-specific MRE with high affinity was obtained. The equilibrium dissociation constant (Kd) of the ssDNA sequence is 0.62 ± 0.21 nM. It also has significant selectivity for atrazine over atrazine metabolites and other pesticides found in environmentally similar locations and concentrations. Furthermore, we have detected environmentally relevant atrazine concentrations in river water using this MRE. The strong affinity and selectivity of the selected atrazine-specific ssDNA validated the stringent SELEX methodology and identified a MRE that will be useful for rapid atrazine detection in environmental samples. 相似文献
7.
Low-temperature, or psychrophilic (<20 degrees C) anaerobic digestion has been proven feasible for the mineralisation of simple wastewaters. In this study, hybrid expanded granular sludge bed-anaerobic filter (EGSB-AF) bioreactors were used to evaluate the feasibility of psychrophilic digestion for the treatment of phenol-containing wastewater. Efficient chemical oxygen demand and phenol removal were observed at organic and phenol loading rates of 5 kg COD m(-3)d(-1) and 0.4-1.2 kg phenol m(-3)d(-1) (400-1200 mg phenol [l wastewater](-1)), respectively. There was no long-term accumulation of volatile fatty acids in the reactor systems. Methanogenic activity was developed under psychrophilic conditions but anaerobic methane-producing populations remained mesophilic throughout the trial of 415 days. 相似文献
8.
Xi Yu Michael J Hounslow Gavin K Reynolds 《American Institute of Chemical Engineers》2015,61(8):2394-2402
Implementation of a Monte Carlo simulation for the solution of population balance equations (PBEs) requires choice of initial sample number (N0), number of replicates (M), and number of bins for probability distribution reconstruction (n). It is found that Squared Hellinger Distance, H2, is a useful measurement of the accuracy of Monte Carlo (MC) simulation, and can be related directly to N0, M, and n. Asymptotic approximations of H2 are deduced and tested for both one‐dimensional (1‐D) and 2‐D PBEs with coalescence. The central processing unit (CPU) cost, C, is found in a power‐law relationship, , with the CPU cost index, b, indicating the weighting of N0 in the total CPU cost. n must be chosen to balance accuracy and resolution. For fixed n, M × N0 determines the accuracy of MC prediction; if b > 1, then the optimal solution strategy uses multiple replications and small sample size. Conversely, if 0 < b < 1, one replicate and a large initial sample size is preferred. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2394–2402, 2015 相似文献
9.
10.
Self-regulation in driving has primarily been studied as a precursor to driving cessation in older people, who minimise driving risk and compensate for physical and cognitive decline by avoiding driving in challenging circumstances, e.g. poor weather conditions, in the dark and at busy times. This research explores whether other demographic groups of drivers adopt self-regulatory behaviours and examines the effects of affective and instrumental attitudes on self-regulation across the lifespan. Quantitative data were collected from 395 drivers. Women were significantly more likely than men to engage in self-regulation, and to be negatively influenced by their emotions (affective attitude). A quadratic effect of age on self-regulation was determined such that younger and older drivers reported higher scores for self-regulation than middle-years’ drivers. However, this effect was affected by experience such that when experience was controlled for, self-regulation increased with age. Nevertheless, anxious driving style and negative affective attitude were independent predictors of self-regulation behaviours. Results suggest that self-regulation behaviours are present across the driving lifespan and may occur as a result of driving anxiety or low confidence rather than as an effect of ageing. 相似文献