全文获取类型
收费全文 | 12831篇 |
免费 | 723篇 |
国内免费 | 77篇 |
专业分类
电工技术 | 320篇 |
综合类 | 25篇 |
化学工业 | 3165篇 |
金属工艺 | 342篇 |
机械仪表 | 334篇 |
建筑科学 | 423篇 |
矿业工程 | 20篇 |
能源动力 | 793篇 |
轻工业 | 1281篇 |
水利工程 | 130篇 |
石油天然气 | 236篇 |
武器工业 | 4篇 |
无线电 | 1478篇 |
一般工业技术 | 2314篇 |
冶金工业 | 756篇 |
原子能技术 | 110篇 |
自动化技术 | 1900篇 |
出版年
2023年 | 233篇 |
2022年 | 549篇 |
2021年 | 696篇 |
2020年 | 500篇 |
2019年 | 562篇 |
2018年 | 765篇 |
2017年 | 555篇 |
2016年 | 585篇 |
2015年 | 407篇 |
2014年 | 563篇 |
2013年 | 1048篇 |
2012年 | 657篇 |
2011年 | 771篇 |
2010年 | 554篇 |
2009年 | 510篇 |
2008年 | 458篇 |
2007年 | 382篇 |
2006年 | 352篇 |
2005年 | 275篇 |
2004年 | 248篇 |
2003年 | 257篇 |
2002年 | 230篇 |
2001年 | 146篇 |
2000年 | 173篇 |
1999年 | 154篇 |
1998年 | 243篇 |
1997年 | 175篇 |
1996年 | 132篇 |
1995年 | 123篇 |
1994年 | 87篇 |
1993年 | 83篇 |
1992年 | 62篇 |
1991年 | 52篇 |
1990年 | 46篇 |
1989年 | 64篇 |
1988年 | 71篇 |
1987年 | 70篇 |
1986年 | 52篇 |
1985年 | 67篇 |
1984年 | 73篇 |
1983年 | 68篇 |
1982年 | 42篇 |
1981年 | 42篇 |
1980年 | 53篇 |
1979年 | 38篇 |
1978年 | 38篇 |
1977年 | 41篇 |
1976年 | 56篇 |
1975年 | 39篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
An improved desulfurization process for removing sulfur from hydro treated diesel oil based on the oxidation of thiophenic type sulfur-containing compounds with H2O2 and acetic acid (AcOH) using H2SO4 as catalyst has been studied. The experimental results show that the sulfone content in the oxidation product increased rapidly with an increase in acetic acid and sulfuric acid ratios from 1:0 to 2:1 mole ratios. The maximum DBT conversion (wt.%) was at 2:1 mole ratio of acetic acid/sulfuric acid. This oxidation process is found to be capable of removing up to 90% of the sulfur compounds in hydro treated real fuels and can provide an alternative way to meet the future sulfur environmental requirements. 相似文献
992.
After introducing the numerical relationship between color and current of a solar cell, it is shown that by using thicker antireflecting coatings, it is possible to fabricate different color silicon solar cells with very similar current, only slightly below the one of the best coating. Representative cases of surface structure, cell quality, and materials for the antireflecting layer are considered to explore the generality of the results for both encapsulated and nonencapsulated solar cells. Experimental support to the conclusion is also presented 相似文献
993.
R.M. Ahmed N.E. Takach S. Taoutaou A. Saasen R. Godøy 《Cement and Concrete Research》2009,39(4):353-361
Foams are being used in a number of petroleum industry applications that exploit their high viscosity and low density. Foamed cement slurries can have superior displacement properties relative to non-foamed cement slurries. This article presents results of an experimental study of foamed cement rheology. Viscosity curves of foamed cements were obtained using a flow-through rotational viscometer. Foamed cements with different foam qualities were generated under different pressures using a foam generator/viscometer apparatus. The foam qualities during the tests ranged from 0% to 30%, and the shear rate varied between 5 s− 1 and 600 s− 1. Experimental results indicate that: i) unlike conventional aqueous foams, low-quality cement foams have a lower viscosity than the base fluid; ii) as the cement foam quality (gas volumetric fraction) increases from 10% to 30%, the viscosity also increases; and iii) the viscosity of low-quality cement foam slightly increases after depressurization or expansion. 相似文献
994.
995.
A silicon random access memory using a single-electron tunnelling transistor (SETT) in the form of a multiple tunnel junction (MTJ) in a silicon nanowire has been assessed in terms of its write speed, retention time, and selectivity at an operating temperature of 4.2 K 相似文献
996.
Fastow R. Ahmed K. Haddad S. Randolph M. Huster C. Hom P. 《Electron Device Letters, IEEE》2000,21(4):184-186
Charge gain, caused by localized defects in the tunnel oxide of floating gate devices, is one of the central reliability concerns of flash memory. In this work, we show that charge motion in the poly sidewall spacers of flash cells can also result in substantial charge gain, for nonoptimized processes. Data showing the time, temperature, and field dependencies of this charge gain mechanism are presented. It is shown that the threshold voltage shift caused by charge motion in the poly sidewall spacers follows the simple factorial expression: ΔV th=C·Vfg·tα ·e-ϵ(a)kT/ 相似文献
997.
Nicolas Magdelaine Pablo S. Rivadeneira Lucy Chaillous AnneLaure FournierGuilloux Michel Krempf Taghreed MohammadRidha Mourad AitAhmed Claude H. Moog 《IET systems biology》2020,14(1):16
Driving blood glycaemia from hyperglycaemia to euglycaemia as fast as possible while avoiding hypoglycaemia is a major problem for decades for type‐1 diabetes and is solved in this study. A control algorithm is designed that guaranties hypoglycaemia avoidance for the first time both from the theory of positive systems point of view and from the most pragmatic clinical practice. The solution consists of a state feedback control law that computes the required hyperglycaemia correction bolus in real‐time to safely steer glycaemia to the target. A rigorous proof is given that shows that the control‐law respects the positivity of the control and of the glucose concentration error: as a result, no hypoglycaemic episode occurs. The so‐called hypo‐free strategy control is tested with all the UVA/Padova T1DM simulator patients (i.e. ten adults, ten adolescents, and ten children) during a fasting‐night scenario and in a hybrid closed‐loop scenario including three meals. The theoretical results are assessed by the simulations on a large cohort of virtual patients and encourage clinical trials.Inspec keywords: biochemistry, medical control systems, blood, diseases, medical computing, closed loop systems, biomedical equipment, state feedback, patient treatment, patient monitoring, biomedical measurement, physiological models, sugarOther keywords: fasting‐night scenario, hybrid closed‐loop scenario, hypoglycaemia‐free artificial pancreas project, blood glycaemia, euglycaemia, type‐1 diabetes, control algorithm, guaranties hypoglycaemia avoidance, pragmatic clinical practice, state feedback control law, required hyperglycaemia correction bolus, rigorous proof, control‐law, glucose concentration error, hypo‐free strategy control 相似文献
998.
Superfast kinetics of Nd+3, Eu+3, and Gd+3 ions were studied on the surfaces of N,N,N\,N\‐tetramethylmalonamide (TMMA) and silsesquioxane (SSQXN‐8) resins. TMMA and SSQXN‐8 were prepared by suspension polymerization and sol–gel routes, respectively. They were identified using elemental analysis, FTIR, H‐NMR, 13C‐NMR, MIP, and BET surface area. Kinetic investigations were performed in batch conditions and different models were used to fit the data; Boyd and Helfferich models were found the best. The diffusion of the ions through the resins were very fast and found to be in the order of 10?16 m2/S. Effective diffusions of the studied ions were found to be 10?15 order of magnitude and directly proportional to the kinetic energy of the transition state. ΔS* values from ?166.044 to ?179.297 J mol?1 K?1 were estimated as entropy stability factors of the system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
999.
N. Borisenko E. Zschippang S. Zein El Abedin A. Bund F. Endres 《Electrochimica acta》2009,54(5):1519-5
The electroreduction of 0.5 M TaF5 on Au(1 1 1) and on polycrystalline gold substrates was investigated at room temperature in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py1,4]TFSA, by cyclic voltammetry, in situ scanning tunneling microscopy (STM) and electrochemical quartz crystal microbalance (EQCM). The electrochemical reduction of TaF5 in the employed ionic liquid occurs in several steps. The first redox process is attributed to the reduction of TaF5 to TaF3, which likely occurs in the solution, as EQCM indicates no mass change. The electrodeposition of tantalum occurs only in a very narrow potential window and is preceded by the formation of various non-stoichiometric tantalum subhalides. Attempts to deposit micrometer thick tantalum layers at room temperature fail, presumably because of kinetic reasons. 相似文献
1000.
El Emam K. Laitenberger O. 《IEEE transactions on pattern analysis and machine intelligence》2001,27(9):851-864
Capture-recapture (CR) models have been proposed as an objective method for controlling software inspections. CR models were originally developed to estimate the size of animal populations. In software, they have been used to estimate the number of defects in an inspected artifact. This estimate can be another source of information for deciding whether the artifact requires a reinspection to ensure that a minimal inspection effectiveness level has been attained. Little evaluative research has been performed thus far on the utility of CR models for inspections with two inspectors. We report on an extensive Monte Carlo simulation that evaluated capture-recapture models suitable for two inspectors assuming a code inspections context. We evaluate the relative error of the CR estimates as well as the accuracy of the reinspection decision made using the CR model. Our results indicate that the most appropriate capture-recapture model for two inspectors is an estimator that allows for inspectors with different capabilities. This model always produces an estimate (i.e., does not fail), has a predictable behavior (i.e., works well when its assumptions are met), will have a relatively high decision accuracy, and will perform better than the default decision of no reinspections. Furthermore, we identify the conditions under which this estimator will perform best 相似文献