全文获取类型
收费全文 | 1738篇 |
免费 | 77篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 287篇 |
金属工艺 | 25篇 |
机械仪表 | 33篇 |
建筑科学 | 60篇 |
矿业工程 | 1篇 |
能源动力 | 35篇 |
轻工业 | 128篇 |
水利工程 | 26篇 |
石油天然气 | 5篇 |
武器工业 | 4篇 |
无线电 | 208篇 |
一般工业技术 | 349篇 |
冶金工业 | 345篇 |
原子能技术 | 9篇 |
自动化技术 | 287篇 |
出版年
2024年 | 5篇 |
2023年 | 26篇 |
2022年 | 31篇 |
2021年 | 48篇 |
2020年 | 33篇 |
2019年 | 44篇 |
2018年 | 63篇 |
2017年 | 45篇 |
2016年 | 57篇 |
2015年 | 44篇 |
2014年 | 48篇 |
2013年 | 121篇 |
2012年 | 105篇 |
2011年 | 151篇 |
2010年 | 107篇 |
2009年 | 103篇 |
2008年 | 95篇 |
2007年 | 91篇 |
2006年 | 83篇 |
2005年 | 67篇 |
2004年 | 43篇 |
2003年 | 36篇 |
2002年 | 32篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 22篇 |
1998年 | 41篇 |
1997年 | 26篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 14篇 |
1993年 | 15篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1976年 | 6篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1970年 | 5篇 |
排序方式: 共有1817条查询结果,搜索用时 15 毫秒
91.
Bin Qiu Susan E. Luczak Tamara L. Wall Aaron M. Kirchhoff Yuxue Xu Mimy Y. Eng Robert B. Stewart Weinian Shou Stephen L. Boehm II Julia A. Chester Weidong Yong Tiebing Liang 《International journal of molecular sciences》2016,17(8)
FKBP5 encodes FK506-binding protein 5, a glucocorticoid receptor (GR)-binding protein implicated in various psychiatric disorders and alcohol withdrawal severity. The purpose of this study is to characterize alcohol preference and related phenotypes in Fkbp5 knockout (KO) mice and to examine the role of FKBP5 in human alcohol consumption. The following experiments were performed to characterize Fkpb5 KO mice. (1) Fkbp5 KO and wild-type (WT) EtOH consumption was tested using a two-bottle choice paradigm; (2) The EtOH elimination rate was measured after intraperitoneal (IP) injection of 2.0 g/kg EtOH; (3) Blood alcohol concentration (BAC) was measured after 3 h limited access of alcohol; (4) Brain region expression of Fkbp5 was identified using LacZ staining; (5) Baseline corticosterone (CORT) was assessed. Additionally, two SNPs, rs1360780 (C/T) and rs3800373 (T/G), were selected to study the association of FKBP5 with alcohol consumption in humans. Participants were college students (n = 1162) from 21–26 years of age with Chinese, Korean or Caucasian ethnicity. The results, compared to WT mice, for KO mice exhibited an increase in alcohol consumption that was not due to differences in taste sensitivity or alcohol metabolism. Higher BAC was found in KO mice after 3 h of EtOH access. Fkbp5 was highly expressed in brain regions involved in the regulation of the stress response, such as the hippocampus, amygdala, dorsal raphe and locus coeruleus. Both genotypes exhibited similar basal levels of plasma corticosterone (CORT). Finally, single nucleotide polymorphisms (SNPs) in FKBP5 were found to be associated with alcohol drinking in humans. These results suggest that the association between FKBP5 and alcohol consumption is conserved in both mice and humans. 相似文献
92.
Sylvia O. Nwosu Jay C. Schleicher Aaron M. Scurto 《The Journal of Supercritical Fluids》2009,51(1):1-9
The use of carbon dioxide in the synthesis of ionic liquids (ILs) has many advantages over conventional solvents. Here, the high-pressure phase equilibria (including CO2 solubility, volume expansion, and mixture critical points) are measured and modeled for the system involved in the synthesis of a model imidazolium ionic liquid 1-hexyl-3-methylimidazolium bromide ([HMIm][Br]) from 1-bromohexane and 1-methylimidazole. The global phase behavior of 1-methylimidazole was investigated and found to be a Type V system (or potentially IV) from the classification of Scott and van Konynenburg with regions of vapor–liquid equilibrium, vapor–liquid–liquid equilibrium, liquid–liquid equilibrium, an upper and lower critical endpoint and mixture critical points. The solubility and volume expansion of CO2 in 1-methylimidazole, 1-bromohexane, a 1:1 mixture of 1-methylimidazole and 1-bromohexane and [HMIm][Br] was determined at 313.15 K and 333.15 K for pressures ranging from 10 to 160 bar. The solubility of CO2 and the volume expansion increases in the order of [HMIm][Br] 1-methylimidazole < 1:1 mixture of reactants < 1-bromohexane. The Peng–Robinson equation of state with van der Waals 2-parameter mixing rules was used with estimated critical properties to well correlate the vapor–liquid equilibrium. The results have important ramifications on the kinetics and process constraints of an actual IL synthesis with CO2. 相似文献
93.
Global phase behavior of imidazolium ionic liquids and compressed 1,1,1,2‐tetrafluoroethane (R‐134a)
Novel processes involving ionic liquids with refrigerant gases have recently been developed. Here, the complete global phase behavior has been measured for the refrigerant gas, 1,1,1,2‐tetrafluoroethane (R‐134a) and 1‐n‐alkyl‐3‐methyl‐imidazolium ionic liquids with the anions hexafluorophosphate [PF6], tetrafluoroborate [BF4] and bis(trifluoromethylsulfonyl)imide [Tf2N] from ~0°C to 105°C and to 33 MPa. All of the systems studied were Type V from the classification scheme of Scott‐van Konynenburg with regions of vapor‐liquid equilibrium, miscible/critical regions, vapor‐liquid‐liquid equilibrium, and upper and lower critical endpoints (UCEP and LCEP). The effect of the alkyl chain length has been investigated, for ethyl‐([EMIm]), n‐butyl‐([BMIm]), and n‐hexyl‐([HMIm]). With increasing chain length, the temperature of the lower critical end points increases and pressure at the mixture critical points decrease. With a common cation, the temperature of the LCEP increased and the mixture critical point pressures decreased in the order of [BF4], [PF6], and [Tf2N]. © 2008 American Institute of Chemical Engineers AIChE J, 2009 相似文献
94.
95.
Nikolai G. Kalugin Irakli Kalichava Christopher Del Barga Juan G. Duque Stephen K. Doorn Aaron V. Gin 《Carbon》2010,48(12):3405-3411
We report on SEM, AFM, and Raman identification of non-planar several monolayer-thick graphene nanostructures with curved shapes. During mechanical exfoliation we obtained graphene flakes with nanowire/nanotube-like objects (diameters between 8 and 35 nm) with cross-sectional profile reminiscent of the Greek capital letter omega (Ω). The curved shapes of these objects were confirmed by AFM and SEM imaging. Non-planar Ω - nanostructures open up new possibilities for graphene electron energy band engineering. 相似文献
96.
Biogeochemical processes in ethanol stimulated uranium-contaminated subsurface sediments 总被引:1,自引:0,他引:1
Mohanty SR Kollah B Hedrick DB Peacock AD Kukkadapu RK Roden EE 《Environmental science & technology》2008,42(12):4384-4390
A laboratory incubation experiment was conducted with uranium-contaminated subsurface sediment to assess the geochemical and microbial community response to ethanol amendment. A classical sequence of terminal electron-accepting processes (TEAPs) was observed in ethanol-amended slurries, with NO3- reduction, Fe(III) reduction, SO4(2-) reduction, and CH4 production proceeding in sequence until all of the added 13C-ethanol (9 mM) was consumed. Approximately 60% of the U(VI) content of the sediment was reduced during the period of Fe(III) reduction. No additional U(VI) reduction took place during the sulfate-reducing and methanogenic phases of the experiment Only gradual reduction of NO3-, and no reduction of U(VI), took place in ethanol-free slurries. Stimulation of additional Fe(III) or SO4(2-) reduction in the ethanol-amended slurries failed to promote further U(VI) reduction. Reverse transcribed 16S rRNA clone libraries revealed major increases in the abundance of organisms related to Dechloromonas, Geobacter, and Herbaspirillum in the ethanol-amended slurries. Phospholipid fatty acids (PLFAs) indicative of Geobacter showed a distinct increase in the amended slurries, and analysis of PLFA 13C/12C ratios confirmed the incorporation of ethanol into these PLFAs. A increase in the abundance of 13C-labeled PLFAs indicative of Desulfobacter, Desulfotomaculum, and Desulfovibrio took place during the brief period of sulfate reduction that followed the Fe(III) reduction phase. Our results show that major redox processes in ethanol-amended sediments can be reliably interpreted in terms of standard conceptual models of TEAPs in sediments. However, the redox speciation of uranium is complex and cannot be explained based on simplified thermodynamic considerations. 相似文献
97.
Aaron S. FisherMian B. Khalid Matthew WidstromPeter Kofinas 《Journal of power sources》2011,196(22):9767-9773
The electrochemical properties of a solid hybrid polymer electrolyte for lithium batteries based upon tri-ethyl sulfonium bis(trifluorosulfonyl) imide (S2TFSI), lithium TFSI, and poly(ethylene oxide) (PEO) is presented. We have synthesized homogenous freestanding films that possess low temperature ionic conductivity and wide electrochemical stability. The hybrid electrolyte has demonstrated ionic conductivity of 0.117 mS cm−1 at 0 °C, and 1.20 mS cm−1 at 25 °C. At slightly elevated temperature ionic conductivity is on the order of 10 mS cm−1. The hybrid electrolyte has demonstrated reversible stability against metallic lithium at the anodic interface and >4.5 V vs. Li/Li+ at the cathodic interface. 相似文献
98.
This article deals with performance evaluation of the discrete ordinates method in terms of its capacity to provide accurate results in solving radiation mode problems with different complexities. The problem formulation is done keeping in view the heat transfer process in an evaporator used in a coal-based thermal power station. The hot gas mass in the evaporator is assumed to be a heat source with two different shapes, spherical and conical. The evaporator walls that are covered with a water cooling jacket are modeled with a convective boundary condition. The gas is assumed to be gray and absorbing–emitting. The solution of the radiative transport equation is carried out using the discrete ordinates method. Parametric studies are performed for a wide range of aspect ratio, extinction coefficient, and convective heat transfer coefficient. The code is validated by comparing the result of discrete ordinates method with the exact and the discrete transfer method for nonradiative as well as radiative equilibrium conditions. 相似文献
99.
Moser DP Fredrickson JK Geist DR Arntzen EV Peacock AD Li SM Spadoni T McKinley JP 《Environmental science & technology》2003,37(22):5127-5134
Biogeochemical processes within riverbed hyporheic zones (HZ) can potentially impact the fate and transport of contaminants. We evaluated a modified freeze core technique for the collection of intact cobble-bed samples from the Columbia River HZ along a stretch of the Hanford Reach in Washington State and investigated microbiological and geochemical parameters of corresponding frozen and unfrozen samples. During three sampling periods (March, May, and November 2000), relatively high numbers of viable aerobic heterotrophic bacteria were recovered from both unfrozen (10(6)-10(7) cfu/g) and frozen samples (10(5)-10(6) cfu/g). Relatively large populations of sulfate-, nitrate-, and iron-reducing bacteria were present, and significant concentrations of acid-volatile sulfide were measured in some samples, indicating that anoxic regions exist within this zone. Cr(VI), a priority groundwater pollutant on adjacent U.S. Department of Energy lands, was probably removed from solution in HZ samples by a combination of microbial activity and chemical reduction, presumably via products of anaerobic microbial metabolism. These results suggest that biogeochemical processes in the Columbia River HZ may contribute to the natural attenuation of Cr(VI). Although freezing modestly diminished recovery of viable bacteria, freeze core techniques proved reliable for the collection of intact hyporheic sediments. 相似文献
100.
Aaron Hand 《集成电路应用》2009,(8)
经济危机不断深入,并且与产业周期的低谷共同作用,半导体产业的生存压力日渐增大。越来越多的器件制造商和代工厂开始在光伏领域寻找机会以期度过财政难关。市场分析公司IC Insights(亚利桑那州,Scottsdale)主要集中在半导体领域,目前也开始向PV产业转移,开始为半导体产业的企业进入这个新兴市场提供帮助。 相似文献