全文获取类型
收费全文 | 2111篇 |
免费 | 75篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 39篇 |
综合类 | 3篇 |
化学工业 | 402篇 |
金属工艺 | 22篇 |
机械仪表 | 35篇 |
建筑科学 | 77篇 |
矿业工程 | 4篇 |
能源动力 | 40篇 |
轻工业 | 160篇 |
水利工程 | 18篇 |
石油天然气 | 3篇 |
无线电 | 321篇 |
一般工业技术 | 327篇 |
冶金工业 | 254篇 |
原子能技术 | 20篇 |
自动化技术 | 462篇 |
出版年
2022年 | 18篇 |
2021年 | 34篇 |
2020年 | 17篇 |
2019年 | 30篇 |
2018年 | 33篇 |
2017年 | 47篇 |
2016年 | 46篇 |
2015年 | 45篇 |
2014年 | 68篇 |
2013年 | 113篇 |
2012年 | 100篇 |
2011年 | 117篇 |
2010年 | 95篇 |
2009年 | 100篇 |
2008年 | 117篇 |
2007年 | 85篇 |
2006年 | 100篇 |
2005年 | 83篇 |
2004年 | 80篇 |
2003年 | 82篇 |
2002年 | 55篇 |
2001年 | 32篇 |
2000年 | 42篇 |
1999年 | 40篇 |
1998年 | 64篇 |
1997年 | 34篇 |
1996年 | 43篇 |
1995年 | 25篇 |
1994年 | 30篇 |
1993年 | 35篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 23篇 |
1987年 | 20篇 |
1986年 | 23篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 21篇 |
1975年 | 12篇 |
1973年 | 13篇 |
1972年 | 10篇 |
排序方式: 共有2187条查询结果,搜索用时 0 毫秒
91.
Fran?ois Zaviska Patrick Drogui Jean-Fran?ois Blais Guy Mercier 《Journal of Applied Electrochemistry》2012,42(2):95-109
The decomposition of bisphenol-A (BPA) in synthetic solution and in municipal effluent was investigated using an electro-oxidation
process. Electrolysis was conducted using a cylindrical electrolytic cell containing two circular anodes (expanded metal)
and two circular cathodes (stainless steel) alternated in the electrode pack. Different anode materials (Ti/SnO2, Ti/IrO2 and Ti/PbO2) were tested, and Ti/PbO2 was found to be the most effective electrode for BPA degradation. An experimental design methodology (23 Box–Behnken design) was applied to determine the optimal experimental conditions in terms of cost effectiveness. The BPA
concentration (C
0 = 1.0 mg l−1) could be optimally diminished by up to 90% by applying a current intensity of 2.0 A for a 100-min reaction period in the
presence of 250 mg Na2SO4 l−1 (used as a supporting electrolyte). Then, the optimal conditions were applied on a municipal wastewater effluent (sampled
after secondary treatment) artificially contaminated with 1 mg BPA l−1 without the addition of a supporting electrolyte. The treatment was more effective with the municipal effluent due to the
presence of a high concentration of chloride ions that could easily be transformed into active chlorine. BPA could be oxidized
by both direct anodic electrochemical oxidation (by means of OH·) and indirect electrochemical oxidation via mediators, such
as hypochlorous acid generated by chloride oxidation. Both actions (direct and indirect effects) lead to the formation of
powerful oxidizing agents capable of rapidly oxidizing BPA. 相似文献
92.
Dodson Guy; Hubbard Roderick E.; Oldfield Tom J.; Smerdon Stephen J.; Wilkinson Anthony J. 《Protein engineering, design & selection : PEDS》1988,2(3):233-237
Recombinant porcine myoglobin has been produced in Escherichiacoli using the cII fusion expression system of Nagai and Th?gersen[Nature, 309, 810812 (1984)]. After processing and reconstitutionwith haem, the protein is gel-electrophoretically and spectrophotometricallyindistinguishable from native pig myoglobin. Large crystalsof both native and recombinant porcine myoglobin were grownfrom 50 mM sodium phosphate, pH 7.1, 80% ammonium sulphate.The crystals belong to space group C2 (a = 156.9 ?, b = 42.0?, c = 92.2 ?, ß = 127.9?) and diffract to a nominal2.5 ? resolution. We plan to explore apomyoglobin as a bindingsurface in studies combining site-directed mutagenesis and X-rayanalysis. These experiments will be extended by studying thebinding of haem analogues to the mutant apoproteins. 相似文献
93.
This article presents, from a historical perspective, some stereological protocols of the first order. Such protocols can
be implemented to quantify statistically the architecture of thermal spray coatings and their relevant features (pores, lamellas,
etc.). A forthcoming Part II of this article will address some key points to implement, from a practical point of view, such
protocols.
相似文献
Ghislain MontavonEmail: |
94.
Silvia Folloni Gianni Bellocchi Adelina Prospero Maddalena Querci William Moens Monica Ermolli Guy Van den Eede 《Food Analytical Methods》2010,3(4):304-312
Real-time PCR (RTi-PCR) is the technique of choice for event-specific quantification of genetically modified organisms (GMOs)
by determining the amount of event with respect to a species-specific reference gene. Reference genes can be amplified from
the genome extracted from Certified Reference Materials (CRMs) or from ad hoc designed plasmids. In the present study, we
statistically evaluate the performance of RTi-PCR protocols for GM maize MON810 event by using both genomic DNA from conventional
CRMs and a plasmid containing sequences representative of four maize species-specific reference genes. The significance of
simple and interaction effects of several variables included in the experimental design on DNA quantification methods and
RTi-PCR were evaluated and discussed. Statistically significant differences on Ct values may have an impact on the GMOs quantification
and consequently on the compliance of GM quantification-established legal thresholds. Our results confirm the reliability
of the plasmid as alternative calibrant for the calculation of GMOs copy number. 相似文献
95.
Shabnam Sanaei Navid Mostoufi Ramin Radmanesh Rahmat Sotudeh‐Gharebagh Christophe Guy Jamal Chaouki 《加拿大化工杂志》2010,88(1):1-11
Effect of temperature on the hydrodynamics of bubbling gas–solid fluidized beds was investigated in this work. Experiments were carried out at different temperatures ranged of 25–600°C and different superficial gas velocities in the range of 0.17–0.78 m/s with sand particles. The time‐position trajectory of particles was obtained by the radioactive particle tracking technique at elevated temperature. These data were used for determination of some hydrodynamic parameters (mean velocity of upward and downward‐moving particles, jump frequency, cycle frequency, and axial/radial diffusivities) which are representative to solids mixing through the bed. It was shown that solids mixing and diffusivity of particles increases by increasing temperature up to around 300°C. However, these parameters decrease by further increasing the temperature to higher than 300°C. This could be attributed to the properties of bubble and emulsion phases. Results of this study indicated that the bubbles grow up to a maximum diameter by increasing the temperature up to 300°C, after which the bubbles become smaller. The results showed that due to the wall effect, there is no significant change in the mean velocity of downward‐moving clusters. In order to explain these trends, surface tension of emulsion between the rising bubble and the emulsion phase was introduced and evaluated in the bubbling fluidized bed. The results showed that surface tension between bubble and emulsion is increased by increasing temperature up to 300°C, however, after that it acts in oppositely. 相似文献
96.
Abhishek Dutta Rahul P. Ekatpure Geraldine J. Heynderickx Axel de Broqueville Guy B. Marin 《Chemical engineering science》2010,65(5):1678-1693
Computational fluid dynamics (CFD) simulations of the hydrodynamic behavior of rotating fluidized beds in static geometry (RFB-SG) are carried out for gas–solid flows. The rotating motion of the reactor bed is induced by the tangential injection of the gas along the circumference of the fluidization chamber. Steep gradients in the gas velocity fields both in radial and tangential direction generate turbulence. The radial and tangential drag forces fluidize the particle bed in both radial and tangential direction.An Eulerian two-fluid model is used. Gas phase turbulence is accounted for by a k–ε model adapted for rotational flows. The RFB-SG simulations provide guidelines for a design and operation with a high efficiency in gas–solid momentum transfer, excellent gas–solid separation and limited solids losses. Hydrodynamic variables like the centrifugal force, the injection pressure, the radial and tangential slip velocities, solids hold-up are calculated for both polymer particles (300 μm, 950 kg/m3, Geldart Group B) and glass beads (70 μm, 2500 kg/m3, Geldart Group A) to allow for a comparison among different fluidization chamber designs. Unstable bed behavior, like slugging and channeling, is also numerically predicted. 相似文献
97.
Michael R. Walsh Marianne E. Walsh Susan Taylor Charles A. Ramsey David B. Ringelberg Jan E. Zufelt Sonia Thiboutot Guy Ampleman Emmanuela Diaz 《Propellants, Explosives, Pyrotechnics》2013,38(3):399-409
Insensitive high explosives are being used in military munitions to counteract unintended detonations during storage and transportation. These formulations contain compounds such as 2,4‐dinitroanisole (DNAN) and 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), which are less sensitive to shock and heat than conventional explosives. We conducted a series of four tests on snow‐covered ice utilizing 60‐mm mortar cartridges filled with 358 g of PAX‐21, a mixture of RDX, DNAN, and ammonium perchlorate. Rounds were detonated high‐ and low‐order using a fuze simulator to initiate detonation. Blow‐in‐place (BIP) operations were conducted on fuzed rounds using an external donor charge or a shaped‐charge initiator. Results indicate that 0.001 % of the original mass of RDX and DNAN were deposited during high‐order detonations, but up to 28 % of the perchlorate remained. For the donor block BIPs, 1 % of the RDX and DNAN remained. Residues masses for these operations were significantly higher than for conventional munitions. Low‐order detonations deposited 10–15 % of their original explosive filler in friable chunks up to 5.2 g in mass. Shaped‐charge BIPs scattered 15 % of the filler and produced chunks up to 15 g. Ammonium perchlorate residue masses were extremely high because of the presence of large AP crystals, up to 400 μm in the recovered particles. 相似文献
98.
Dr. Mélissa Degardin Dr. Sharon Wein Dr. Jean‐Frédéric Duckert Marjorie Maynadier Dr. Alexandre Guy Dr. Thierry Durand Prof. Roger Escale Dr. Henri Vial Dr. Yen Vo‐Hoang 《ChemMedChem》2014,9(2):300-304
Plasmodium falciparum is responsible of the most severe form of malaria, and new targets and novel chemotherapeutic scaffolds are needed to fight emerging multidrug‐resistant strains of this parasite. Bis‐alkylguanidines have been designed to mimic choline, resulting in the inhibition of plasmodial de novo phosphatidylcholine biosynthesis. Despite potent in vitro antiplasmodial and in vivo antimalarial activities, a major drawback of these compounds for further clinical development is their low oral bioavailability. To solve this issue, various modulations were performed on bis‐alkylguanidines. The introduction of N‐disubstituents on the guanidino motif improved both in vitro and in vivo activities. On the other hand, in vivo pharmacological evaluation in a mouse model showed that the N‐hydroxylated derivatives constitute the first oral bioprecursors in bis‐alkylguanidine series. This study paves the way for bis‐alkylguanidine‐based oral antimalarial agents targeting plasmodial phospholipid metabolism. 相似文献
99.
A systematic methodology for kinetic modeling of chemical reactions applied to n‐hexane hydroisomerization 下载免费PDF全文
Kenneth Toch Joris W. Thybaut Guy B. Marin 《American Institute of Chemical Engineers》2015,61(3):880-892
Kinetic modeling provides chemical engineers with a unique opportunity to better understand reaction kinetics in general and the underlying chemistry in particular. How to systematically approach a modeling assignment in chemical reaction kinetics is typically less clear, especially for novices in the field. The proposed modeling methodology pursues an adequate compromise between statistical significance and physical meaning of the kinetic model and the corresponding parameters and typically results in models of an appropriate complexity. It comprises the following activities: (1) data analysis, aiming at qualitative information on the reaction mechanism and corresponding rate equations, (2) model regression to quantify this information via optimal parameter values, and (3) validation of the statistical significance and physical meaning of the parameter estimates. This methodology is successfully applied to n‐hexane hydroisomerization on a bifunctional catalyst. © 2014 American Institute of Chemical Engineers AIChE J, 61: 880–892, 2015 相似文献
100.
In this paper we present adsorption isotherms of carbon dioxide on five different activated carbons from CHEMVIRON CARBON Belgium (Centaur HSV, BPL 410, F30-470, WS 42, Reactivated) and on a carbon molecular sieve from BERGBAU FORSCHUNG Gmbh (CMS II). The temperature is 303 K and the pressure ranges from 100 kPa up to 4000 kPa. Such conditions correspond to relative pressures ranging from 0.01 to 0.5. We also provide, for the same six sorbents, the nitrogen isotherms at 77 K (pressure: 0.001 to 100 kPa, relative pressure: 10-5 to 1). A theoretical treatment based on the Dubinin-Radushkevich and Stoeckli concept is presented and applied to the experimental results in order to obtain the micropore size distribution function (considered as Gaussian) of each sorbent. Using the CO2 data, it is possible to point out important structural differences between the six carbons. The theoretical treatment provides micropore size distribution functions in agreement with what is physically expected. Using N2 data, the structural differences are not so well marked. As a consequence, the structural parameters provided by the theoretical treatment are not reliable: except for the total micropore volume, they fluctuate strongly when changing the relative pressure domain of the used data. 相似文献