全文获取类型
收费全文 | 13523篇 |
免费 | 1917篇 |
国内免费 | 1202篇 |
专业分类
电工技术 | 606篇 |
技术理论 | 1篇 |
综合类 | 691篇 |
化学工业 | 2103篇 |
金属工艺 | 433篇 |
机械仪表 | 1586篇 |
建筑科学 | 178篇 |
矿业工程 | 130篇 |
能源动力 | 181篇 |
轻工业 | 716篇 |
水利工程 | 44篇 |
石油天然气 | 772篇 |
武器工业 | 212篇 |
无线电 | 4523篇 |
一般工业技术 | 2299篇 |
冶金工业 | 150篇 |
原子能技术 | 532篇 |
自动化技术 | 1485篇 |
出版年
2024年 | 65篇 |
2023年 | 329篇 |
2022年 | 475篇 |
2021年 | 551篇 |
2020年 | 564篇 |
2019年 | 499篇 |
2018年 | 545篇 |
2017年 | 603篇 |
2016年 | 667篇 |
2015年 | 694篇 |
2014年 | 838篇 |
2013年 | 825篇 |
2012年 | 987篇 |
2011年 | 1028篇 |
2010年 | 737篇 |
2009年 | 757篇 |
2008年 | 741篇 |
2007年 | 782篇 |
2006年 | 700篇 |
2005年 | 555篇 |
2004年 | 520篇 |
2003年 | 489篇 |
2002年 | 405篇 |
2001年 | 289篇 |
2000年 | 316篇 |
1999年 | 282篇 |
1998年 | 228篇 |
1997年 | 238篇 |
1996年 | 207篇 |
1995年 | 147篇 |
1994年 | 150篇 |
1993年 | 105篇 |
1992年 | 90篇 |
1991年 | 61篇 |
1990年 | 48篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
Bianca Stoean Dumitrita Rugina Monica Focsan Ana-Maria Craciun MÎdÎlina Nistor Tamas Lovasz Alexandru Turza Ioan-Dan Porumb Emese Gl Castelia Cristea Luminita Silaghi-Dumitrescu Simion Astilean Luiza Ioana Gaina 《International journal of molecular sciences》2021,22(6)
We report here the synthesis and structural characterization of novel cationic (phenothiazinyl)vinyl-pyridinium (PVP) dyes, together with optical (absorption/emission) properties and their potential applicability as fluorescent labels. Convective heating, ultrasound irradiation and mechanochemical synthesis were considered as alternative synthetic methodologies proficient for overcoming drawbacks such as long reaction time, nonsatisfactory yields or solvent requirements in the synthesis of novel dye (E)-1-(3-chloropropyl)-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium bromide 3d and its N-alkyl-2-methylpyridinium precursor 1c. The trans geometry of the newly synthesized (E)-4-(2-(7-bromo-10-ethyl-10H-phenothiazin-3-yl)vinyl)-1-methylpyridin-1-ium iodide 3b and (E)-1-methyl-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium tetrafluoroborate 3a′ was confirmed by single crystal X-ray diffraction. A negative solvatochromism of the dyes in polar solvents was highlighted by UV-Vis spectroscopy and explanatory insights were supported by molecular modeling which suggested a better stabilization of the lowest unoccupied molecular orbitals (LUMO). The photostability of the dye 3b was investigated by irradiation at 365 nm in different solvents, while the steady-state and time-resolved fluorescence properties of dye 3b and 3a′ in solid state were evaluated under one-photon excitation at 485 nm. The in vitro cytotoxicity of the new PVP dyes on B16-F10 melanoma cells was evaluated by WST-1 assay, while their intracellular localization was assessed by epi-fluorescence conventional microscopy imaging as well as one- and two-photon excited confocal fluorescence lifetime imaging microscopy (FLIM). PVP dyes displayed low cytotoxicity, good internalization inside melanoma cells and intense fluorescence emission inside the B16-F10 murine melanoma cells, making them suitable staining agents for imaging applications. 相似文献
63.
Aiming at the requirements of high-resolution imaging and high integration of the blast furnace radar,this paper presents a method for designing a wideband microstrip array antenna,which broadens the antenna bandwidth through the design of parasitic patches and air layers.By combining multi-input multi-output (MIMO) radar and synthetic aperture radar (SAR) imaging principles,a linear MIMO array is designed,and a near-field simulation imaging experiment is performed on the simulated feed line through the wave number domain imaging algorithm.Simulation results show that the gain of the main lobe of the antenna can reach 14.05 dBi,the reflection coefficient is less than -10 dB,the absolute bandwidth is 5.25 GHz,the operating frequency is 20.67~25.92 GHz,and the range resolution is increased to 3 cm compared with the existing blast furnace radar.The average error of the azimuth direction of the simulated material line imaging is 0.008 m,and the range direction is 0.0011 m.Compared with the traditional microstrip array antenna,this antenna effectively widens the bandwidth,and the range resolution is higher than that of the traditional blast furnace radar.It can accurately obtain the shape information on the simulated material line,and has an engineering application value for blast furnace surface monitoring. 相似文献
64.
65.
Wei Ren Fuchun Nan Dr. Shumu Li Prof. Sijin Yang Prof. Jiechao Ge Prof. Zhenwen Zhao 《ChemMedChem》2021,16(4):646-653
Negatively charged fluorescent carbon dots (CDs, Em=608 nm) were hydrothermally prepared from thiophene phenylpropionic acid polymers and then successfully loaded with the positively charged anticancer cargo coptisine, which suffers from poor bioavailability. The formed CD-coptisine complexes were thoroughly characterized by particle size, morphology, drug loading efficiency, drug release, cellular uptake and cellular toxicity in vitro and antitumor activities in vivo. In this nano-carrier system, red emissive CDs possess multiple advantages as follows: 1) high drug loading efficiency (>96 %); 2) sustained drug release; 3) enhanced drug efficacy towards cancer cells; 4) EPR effect; 5) drug release tracing with near-infrared imaging. These properties indicated that red emissive CDs prepared from polymers could be used as a novel drug delivery system with integrated therapeutic and imaging functions in cancer therapy, which are expected to have great potential in future clinical applications. 相似文献
66.
Romina Combi Maria Salsone Chiara Villa Luigi Ferini-Strambi 《International journal of molecular sciences》2021,22(8)
Dementia with Lewy bodies (DLB) is one of the most common causes of dementia and belongs to the group of α-synucleinopathies. Due to its clinical overlap with other neurodegenerative disorders and its high clinical heterogeneity, the clinical differential diagnosis of DLB from other similar disorders is often difficult and it is frequently underdiagnosed. Moreover, its genetic etiology has been studied only recently due to the unavailability of large cohorts with a certain diagnosis and shows genetic heterogeneity with a rare contribution of pathogenic mutations and relatively common risk factors. The rapid increase in the reported cases of DLB highlights the need for an easy, efficient and accurate diagnosis of the disease in its initial stages in order to halt or delay the progression. The currently used diagnostic methods proposed by the International DLB consortium rely on a list of criteria that comprises both clinical observations and the use of biomarkers. Herein, we summarize the up-to-now reported knowledge on the genetic architecture of DLB and discuss the use of prodromal biomarkers as well as recent promising candidates from alternative body fluids and new imaging techniques. 相似文献
67.
Caroline K. Brennan Marya Y. Ornelas Zi W. Yao Prof. Dr. Jennifer A. Prescher 《Chembiochem : a European journal of chemical biology》2021,22(16):2650-2654
Bioluminescent tools have been used for decades to image processes in complex tissues and preclinical models. However, few distinct probes are available to probe multicellular interactions. We and others are addressing this limitation by engineering new luciferases that can selectively process synthetic luciferin analogues. In this work, we explored naphthylamino luciferins as orthogonal bioluminescent probes. Three analogues were prepared using an optimized synthetic route. The luciferins were found to be robust emitters with native luciferase in vitro and in cellulo. We further screened the analogues against libraries of luciferase mutants to identify unique enzyme-substrate pairs. The new probes can be used in conjunction with existing bioluminescent tools for multi-component imaging. 相似文献
68.
涤纶帘子线的等离子体改性 总被引:4,自引:0,他引:4
运用等离子体对涤纶帘子线进行改性处理,从而提高涤纶帘子线与橡胶的粘合性,并用X光电子能谱和红外光谱表面分析技术分析改性后的涤纶帘子线表面结构所发生的变化。 相似文献
69.
Gabriel LaPlante Andrew E. Marble Bryce MacMillan Pearl Lee-Sullivan Bruce G. Colpitts Bruce J. Balcom 《NDT & E International》2005,38(6):501-507
Water ingress inside honeycomb sandwich panels during service has been linked to in-flight failure in some aircraft. There is an ongoing effort to develop nondestructive testing methods to detect the presence of water within the panels. Magnetic resonance (MR) represents an attractive approach in that it is sensitive to moisture. Using a unilateral MR sensor, testing can be applied directly to the surface of the panel. The viability of MR is demonstrated through laboratory imaging of both water within sandwich panels, as well as the adhesive itself. The detection of water using a one-sided handheld MR sensor is presented. It is shown that simple detection, as well as spatial localization of water within sandwich panels is possible. 相似文献
70.
In this paper the heteropoly complexes K_n[Ga(H_20)MW_(11)O_39)]·xH_20 [M=Cu(Ⅱ), Co(Ⅱ), Cr(Ⅲ),Fe(Ⅲ), Mn(Ⅳ)] have been prepared in this laboratory firstly. The products were characterized by chemicalanalysis, ionexchange, IR, UV and X-ray powder diffraction. 相似文献