全文获取类型
收费全文 | 1219篇 |
免费 | 58篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 306篇 |
金属工艺 | 12篇 |
机械仪表 | 30篇 |
建筑科学 | 26篇 |
能源动力 | 30篇 |
轻工业 | 115篇 |
水利工程 | 5篇 |
石油天然气 | 6篇 |
无线电 | 94篇 |
一般工业技术 | 176篇 |
冶金工业 | 295篇 |
原子能技术 | 9篇 |
自动化技术 | 159篇 |
出版年
2023年 | 5篇 |
2022年 | 39篇 |
2021年 | 46篇 |
2020年 | 25篇 |
2019年 | 16篇 |
2018年 | 35篇 |
2017年 | 29篇 |
2016年 | 26篇 |
2015年 | 23篇 |
2014年 | 23篇 |
2013年 | 54篇 |
2012年 | 45篇 |
2011年 | 66篇 |
2010年 | 42篇 |
2009年 | 54篇 |
2008年 | 63篇 |
2007年 | 37篇 |
2006年 | 41篇 |
2005年 | 33篇 |
2004年 | 27篇 |
2003年 | 36篇 |
2002年 | 35篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 24篇 |
1998年 | 102篇 |
1997年 | 62篇 |
1996年 | 39篇 |
1995年 | 25篇 |
1994年 | 13篇 |
1993年 | 28篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1971年 | 4篇 |
排序方式: 共有1279条查询结果,搜索用时 31 毫秒
131.
A fuzzy operator for the enhancement of blurred and noisy images 总被引:4,自引:0,他引:4
Rule-based fuzzy operators are a novel class of operators specifically designed in order to apply the principles of approximate reasoning to digital image processing. This paper shows how a fuzzy operator that is able to perform detail sharpening but is insensitive to noise can be designed. The results obtainable by the proposed technique in the enhancement of a real image are presented. 相似文献
132.
为传感器提供缓冲 若传感器无法驱动模拟/数字转换器的电容负载,可以利用运算放大器为其提供缓冲.由于许多应用系统都规定只可采用一个电源供应,因此所选运算放大器的工作电压必须与模拟/数字转换器的电压相同,这一点非常重要.虽然共用供电电压有助于精简系统设计,节省成本,但运算放大器因为受供电电压的掣肘,以致其输入输出能力无法得到充分发挥.以ADC121S101为例,由于芯片的参考电压(VREF)也同时是供电电压,因此选用设有轨到轨输出(RRO)功能的运算放大器如LMP2011较为理想. 相似文献
133.
Target Hopping as a Useful Tool for the Identification of Novel EphA2 Protein–Protein Antagonists
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Daniele Pala Dr. Simonetta Russo Dr. Riccardo Castelli Dr. Iftiin Hassan‐Mohamed Dr. Carmine Giorgio Dr. Alessio Lodola 《ChemMedChem》2014,9(1):67-72
Lithocholic acid (LCA), a physiological ligand for the nuclear receptor FXR and the G‐protein‐coupled receptor TGR5, has been recently described as an antagonist of the EphA2 receptor, a key member of the ephrin signalling system involved in tumour growth. Given the ability of LCA to recognize FXR, TGR5, and EphA2 receptors, we hypothesized that the structural requirements for a small molecule to bind each of these receptors might be similar. We therefore selected a set of commercially available FXR or TGR5 ligands and tested them for their ability to inhibit EphA2 by targeting the EphA2‐ephrin‐A1 interface. Among the selected compounds, the stilbene carboxylic acid GW4064 was identified as an effective antagonist of EphA2, being able to block EphA2 activation in prostate carcinoma cells, in the micromolar range. This finding proposes the “target hopping” approach as a new effective strategy to discover new protein–protein interaction inhibitors. 相似文献
134.
135.
136.
Brusseau ML Carroll KC Allen T Baker J Diguiseppi W Hatton J Morrison C Russo A Berkompas J 《Environmental science & technology》2011,45(12):5352-5358
A large-scale permanganate-based in situ chemical oxidation (ISCO) effort has been conducted over the past ten years at a federal Superfund site in Tucson, AZ, for which trichloroethene (TCE) is the primary contaminant of concern. Remediation performance was assessed by examining the impact of treatment on contaminant mass discharge, an approach that has been used for only a very few prior ISCO projects. Contaminant mass discharge tests were conducted before and after permanganate injection to measure the impact at the source-zone scale. The results indicate that ISCO caused a significant reduction in mass discharge (approximately 75%). The standard approach of characterizing discharge at the source-zone scale was supplemented with additional characterization at the plume scale, which was evaluated by examining the change in contaminant mass discharge associated with the pump-and-treat system. The integrated contaminant mass discharge decreased by approximately 70%, consistent with the source-zone-scale measurements. The integrated mass discharge rebounded from 0.1 to 0.2 kg/d within one year after cessation of permanganate injections, after which it has been stable for several years. Collection of the integrated contaminant mass discharge data throughout the ISCO treatment period provided a high-resolution, real-time analysis of the site-wide impact of ISCO, thereby linking source-zone remediation to impacts on overall risk. The results indicate that ISCO was successful in reducing contaminant mass discharge at this site, which comprises a highly heterogeneous subsurface environment. Analysis of TCE sediment concentration data for core material collected before and after ISCO supports the hypothesis that the remaining mass discharge is associated in part with poorly accessible contaminant mass residing within lower-permeability zones. 相似文献
137.
Buckypapers (BPs) are free standing thin sheets made of carbon nanotubes, such as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) or their mixtures. In this research, through in situ electrical resistance measurements, we studied the electrical conductance changes of carbon nanotube networks (NTNs) in various BP samples from complete immersion to evaporation using different chemical solvents. BP samples demonstrated a 20-30% decrease in conductance upon the immersion and almost full recovery after the drying process. We found that by pre-stressing, BP samples demonstrated highly reproducible patterns of conductance changes corresponding to solvent quantity. This feature can be potentially used for sensor applications to simultaneously detect both the occurrence and the amount of organic solvent leakage. 相似文献
138.
ABSTRACT: The objective of this study was to investigate quality changes of salmon fillet muscle during thermal sterilization processes. Small samples (D 30 mm × H 6 mm) from the central dorsal region were heated in an oil bath at 121.1 °C for periods varying from 5 to 120 min. The quality variations along the longitudinal axis of salmon fillets (raw and heated) were examined. The quality properties studied included shear force, color, cook loss, and shrinkage. To minimize the influence of the heterogeneity of the salmon muscle, a multiple thin blade texture device was developed for shear force measurement and a computer vision system was used to facilitate accurate measurements of color and shrinkage. The red muscle was firmer than the white muscle in the raw but not in heated samples. Muscle from the central dorsal region had a lower cook loss and less shrinkage than samples from either the anterior or posterior region following heating. The greatest change in quality occurred within the 1st 10 min of heating at 121.1 °C. Shear force measurements following heating indicated 2 peaks, one corresponding to 5 min and the second for 60 min processing at 121.1 °C. Possible mechanisms were discussed. 相似文献
139.
Chakrapani V. Varanasi Leon Chuck Lyle Brunke Jack Burke Andrew D. Chaney Paul N. Barnes 《Journal of Electronic Materials》2007,36(10):1265-1269
A simple testing method is used to compare the yield strengths (YS) of biaxially textured metallic substrates (Ni and its
alloys) presently under development for YBa2Cu3O7−x
coated conductors. This method is based on a retired ASTM D3379 tensile test standard method that was originally recommended
for single filament materials. Several common textured substrates, such as Ni, Ni-3at.%W, and Ni-5at.%W, procured from different
manufacturers, were tested using this method, and the data were compared with the values reported in the literature. A new
alloy substrate (constantan (Cu55-Ni44-Mn1wt.%)) that is biaxially textured in-house was also tested using this method, and
the YS data were compared with those of other substrates. For the substrates used in this study, the data obtained using this
method indicated that Ni substrates have YS of ∼52 MPa, Ni-3at.%W substrates have YS of ∼106 MPa, Ni-5at.%W substrates have
YS 163 MPa, and Cu55-Ni44-Mn1 wt.% substrates have YS of 74 MPa. 相似文献
140.
V Bonfante S Viviani A Santoro L Devizzi A Di Russo M Zanini F Soncini H Soto Parra P Valagussa G Bonadonna 《Canadian Metallurgical Quarterly》1998,103(2):533-535
Twenty-six patients with relapsed or refractory Hodgkin's disease (HD) were treated with an intensive salvage regimen combining ifosfamide (3000 mg/m2/d, days 1-4 through continuous intravenous infusion) and vinorelbine (25 mg/m2, i.v. days 1 and 5) with mesna uroprotection and G-CSF support. Courses were given at 3-week intervals. Ten patients achieved a complete and 10 patients a partial response, yielding an overall response rate of 77%. The main toxic effect was neutropenia and the combination was well tolerated. 相似文献