全文获取类型
收费全文 | 586篇 |
免费 | 42篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 179篇 |
金属工艺 | 10篇 |
机械仪表 | 11篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 50篇 |
轻工业 | 55篇 |
水利工程 | 12篇 |
石油天然气 | 8篇 |
无线电 | 54篇 |
一般工业技术 | 101篇 |
冶金工业 | 28篇 |
原子能技术 | 2篇 |
自动化技术 | 94篇 |
出版年
2024年 | 5篇 |
2023年 | 15篇 |
2022年 | 30篇 |
2021年 | 36篇 |
2020年 | 38篇 |
2019年 | 27篇 |
2018年 | 44篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 22篇 |
2014年 | 21篇 |
2013年 | 48篇 |
2012年 | 37篇 |
2011年 | 39篇 |
2010年 | 27篇 |
2009年 | 37篇 |
2008年 | 29篇 |
2007年 | 19篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有632条查询结果,搜索用时 15 毫秒
51.
Bonin PM Bejan D Schutt L Hawari J Bunce NJ 《Environmental science & technology》2004,38(5):1595-1599
Electrochemical reduction of RDX, hexahydro-1,3,5-trinitro-1,3,5-triazine, a commercial and military explosive, was examined as a possible remediation technology for treating RDX-contaminated groundwater. A cascade of divided flow-through cells was used, with reticulated vitreous carbon cathodes and IrO2/Ti dimensionally stable anodes, initially using acetonitrile/water solutions to increase the solubility of RDX. The major degradation pathway involved reduction of RDX to the corresponding mononitroso compound, followed by ring cleavage to yield formaldehyde and methylenedinitramine. The reaction intermediates underwent further reduction and/or hydrolysis, the net result being the complete transformation of RDX to small molecules. The rate of degradation increased with current density, but the current efficiency was highest at low current densities. The technique was extended successfully both to 100% aqueous solutions of RDX and to an undivided electrochemical cell. 相似文献
52.
The characterization of sinusoidal signals with time varying amplitude and phase is useful and applicable for many
fields. Therefore several algorithms have been suggested to estimate main aspects of these signals. Within no
standard approach to test the properties of these algorithms, it seems to be helpful to discuss a large class of
algorithms according to their properties. In this paper, six methods of estimating dynamic phasor have been reviewed
and discussed which three of them are based on least square and others are based on Kalman filter. Taylor expansion
is used as a first step and continued with least square or Kalman filter in accordance with the proposal observer of
each method. The theoretical processes of these methods are briefly clarified. The characterizations have been made
by some tests in time and frequency domains. The tests include amplitude step, phase step, frequency step,
frequency response, total vector error, transient monitor, noise, sample number, computation time, harmonic and DC
offset which build a framework to compare the different methods. 相似文献
53.
Rasheed S Haider R Hassan N Pachón H Islam S Jalal CS Sanghvi TG 《Food and nutrition bulletin》2011,32(3):192-200
54.
Jalal Salami Akio Shibata Daniel Meier Edgar Kochka Satoshi Yamanaka Preston Davis John Easoz Toru Abe Kazuo Kinoshita 《Solar Energy Materials & Solar Cells》1997,48(1-4)
This paper presents, for the first time, a low-cost, high-throughput manufacturing approach for fabricating n-base dendritic web silicon solar cells with selectively doped emitters and self-aligned aluminum contacts using rapid thermal processing (RTP) and screen printing. The self-aligned locally diffused emitter (SALDE) structure is p+ nn++ where aluminum is screen-printed on a boron-doped emitter and fired in a belt furnace to form a deep self-doped p+-layer and a self-aligned positive contact to the emitter according to the well-known aluminum-silicon (Al---Si) alloying process. The SALDE structure preserves the shallow emitter (20.2 μm) everywhere except directly beneath the emitter contact. There the junction depth is greater than 5 μm, as desired, in order to shield carriers in the bulk silicon from that part of the silicon surface covered by metal where the recombination rate is high. This structure is realized by using n-base (rather than p-base) substrates and by utilizing screen-printed aluminum (rather than silver) emitter contacts. Prototype dendritic web silicon (web) cells (25 cm2 area) with efficiencies up to 13.2% have been produced. 相似文献
55.
Hameed A. Al‐Attar Gareth C. Griffiths Tom N. Moore Mustafa Tavasli Mark A. Fox Martin R. Bryce Andrew P. Monkman 《Advanced functional materials》2011,21(12):2376-2382
A new family of highly soluble electrophosphorescent dopants based on a series of tris‐cyclometalated iridium(III) complexes (1–4) of 2‐(carbazol‐3‐yl)‐4/5‐R‐pyridine ligands with varying molecular dipole strengths have been synthesized. Highly efficient, solution‐processed, single‐layer, electrophosphorescent diodes utilizing these complexes have been prepared and characterized. The high triplet energy poly(9‐vinylcarbazole) PVK is used as a host polymer doped with 2‐(4‐biphenylyl)‐5‐(4‐tert‐butyl‐phenyl)‐1,3,4‐oxadiazole (PBD) for electron transport. Devices with a current efficiency of 40 cd A?1 corresponding to an EQE of 12% can thus be achieved. The effect of the type and position of the substituent (electron‐withdrawing group (CF3) and electron‐donating group (OMe)) on the molecular dipole moment of the complexes has been investigated. A correlation between the absorption strength of the singlet metal‐to‐ligand charge‐transfer (1MLCT) transition and the luminance spectral red shift as a function of solvent polarity is observed. The strength of the transition dipole moments for complexes 1–4 has also been obtained from TD‐DFT computations, and is found to be consistent with the observed molecular dipole moments of these complexes. The relatively long lifetime of the excitons of the phosphorescence (microseconds) compared to the charge‐carrier scattering time (less than nanoseconds), allows the transition dipole moment to be considered as a “quasi permanent dipole”. Therefore, the carrier mobility is sufficiently affected by the long‐lived transition dipole moments of the phosphorescent molecules, which are randomly oriented in the medium. The dopant dipoles cause positional and energetic disorder because of the locally modified polarization energy. Furthermore, the electron‐withdrawing group CF3 induces strong carrier dispersion that enhances the electron mobility. Therefore, the strong transition dipole moment in complexes 3 and 4 perturbs both electron and hole mobilities, yielding a reduction in exciton formation and an increase in the device dark current, thereby decreasing the device efficiency. 相似文献
56.
Fournier D Halasz A Thiboutot S Ampleman G Manno D Hawari J 《Environmental science & technology》2004,38(15):4130-4133
Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a recalcitrant energetic chemical that tends to accumulate in soil, close to the surface. The present study describes the aerobic biodegradability of HMX using Phanerochaete chrysosporium. When added to 7 day old static P. chrysosporium liquid cultures, HMX (600 nmol) degraded within 25 days of incubation. The removal of HMX was concomitant with the formation of transient amounts of its mono-nitroso derivative (1-NO-HMX). The latter apparently degraded via two potential routes: the first involved N-denitration followed by hydrolytic ring cleavage, and the second involved alpha-hydroxylation prior to ring cleavage. The degradation of 1-NO-HMX gave the ring-cleavage product 4-nitro-2,4-diazabutanal (NDAB), nitrite (NO2 -), nitrous oxide (N2O), and formaldehyde (HCHO). Using [14C]-HMX, we obtained 14CO2 (70% in 50 days), representing three C atoms of HMX. Incubation of real soils, contaminated with either HMX (403 micromol kg(-1)) (military base soil) or HMX (3057 micromol kg(-1)), and RDX (342 micromol kg(-1)) (ammunition soil) with the fungus led to 75 and 19.8% mineralization of HMX (liberated 14CO2), respectively, also via the intermediary formation of 1-NO-HMX. Mineralization in the latter soil increased to 35% after the addition of glucose, indicating that a fungus-based remediation process for heavily contaminated soils is promising. The present findings improve our understanding about the degradation pathway of HMX and demonstrate the utility of using the robust and versatile fungus P. chrysosporium to develop effective remediation processes for the removal of HMX. 相似文献
57.
Amir Hameed Pawel Poznanski Anna Nadolska-Orczyk Waclaw Orczyk 《International journal of molecular sciences》2022,23(21)
Global climate change and the urgency to transform crops require an exhaustive genetic evaluation. The large polyploid genomes of food crops, such as cereals, make it difficult to identify candidate genes with confirmed hereditary. Although genome-wide association studies (GWAS) have been proficient in identifying genetic variants that are associated with complex traits, the resolution of acquired heritability faces several significant bottlenecks such as incomplete detection of structural variants (SV), genetic heterogeneity, and/or locus heterogeneity. Consequently, a biased estimate is generated with respect to agronomically complex traits. The graph pangenomes have resolved this missing heritability and provide significant details in terms of specific loci segregating among individuals and evolving to variations. The graph pangenome approach facilitates crop improvements through genome-linked fast breeding. 相似文献
58.
Muhammad Ikram Mohammad Naeem Muhammad Zahoor Marlia Mohd Hanafiah Adeleke Abdulrahman Oyekanmi Noor Ul Islam Midrar Ullah Mater H. Mahnashi Amer Al Ali Naif A. Jalal Farkad Bantun Aiman M. Momenah Abdul Sadiq 《International journal of molecular sciences》2022,23(18)
The azo dye orange II is used extensively in the textile sector for coloring fabrics. High concentrations of it are released into aqueous environments through textile effluents. Therefore, its removal from textile wastewater and effluents is necessary. Herein, initially, we tested 11 bacterial strains for their capabilities in the degradation of orange II dye. It was revealed in the preliminary data that B. subtilis can more potently degrade the selected dye, which was thus used in the subsequent experiments. To achieve maximum decolorization, the experimental conditions were optimized whereby maximum degradation was achieved at: a 25 ppm dye concentration, pH 7, a temperature of 35 °C, a 1000 mg/L concentration of glucose, a 1000 mg/L urea concentration, a 666.66 mg/L NaCl concentration, an incubation period of 3 days, and with hydroquinone as a redox mediator at a concentration of 66.66 mg/L. The effects of the interaction of the operational factors were further confirmed using response surface methodology, which revealed that at optimum conditions of pH 6.45, a dye concentration of 17.07 mg/L, and an incubation time of 9.96 h at 45.38 °C, the maximum degradation of orange II can be obtained at a desirability coefficient of 1, estimated using the central composite design (CCD). To understand the underlying principles of degradation of the metabolites in the aliquot mixture at the optimized condition, the study steps were extracted and analyzed using GC-MS(Gas Chromatography Mass Spectrometry), FTIR(Fourier Transform Infrared Spectroscopy), 1H and carbon 13 NMR(Nuclear Magnetic Resonance Spectroscopy). The GC-MS pattern revealed that the original dye was degraded into o-xylene and naphthalene. Naphthalene was even obtained in a pure state through silica gel column isolation and confirmed using 1H and 13C NMR spectroscopic analysis. Phytotoxicity tests on Vigna radiata were also conducted and the results confirmed that the dye metabolites were less toxic than the parent dye. These results emphasize that B. subtilis should be used as a potential strain for the bioremediation of textile effluents containing orange II and other toxic azo dyes. 相似文献
59.
The Web has evolved into a dominant digital medium for conducting many types of online transactions such as shopping, paying
bills, making travel plans, etc. Such transactions typically involve a number of steps spanning several Web pages. For sighted
users these steps are relatively straightforward to do with graphical Web browsers. But they pose tremendous challenges for
visually impaired individuals. This is because screen readers, the dominant assistive technology used by visually impaired
users, function by speaking out the screen’s content serially. Consequently, using them for conducting transactions can cause
considerable information overload. But usually one needs to browse only a small fragment of a Web page to do a step of a transaction
(e.g., choosing an item from a search results list). Based on this observation this paper presents a model-directed transaction
framework to identify, extract and aurally render only the “relevant” page fragments in each step of a transaction. The framework
uses a process model to encode the state of the transaction and a concept model to identify the page fragments relevant for
the transaction in that state. We also present algorithms to mine such models from click stream data generated by transactions
and experimental evidence of the practical effectiveness of our models in improving user experience when conducting online
transactions with non-visual modalities. 相似文献
60.
Adherence rates to ferric citrate as compared to active control in patients with end stage kidney disease on dialysis
下载免费PDF全文
![点击此处可从《Hemodialysis international. International Symposium on Home Hemodialysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Diana Jalal Molly McFadden Jamie P. Dwyer Kausik Umanath Erwin Aguilar Yoram Yagil Barbara Greco Mohammed Sika Julia B. Lewis Tom Greene Simin Goral 《Hemodialysis international. International Symposium on Home Hemodialysis》2017,21(2):243-249
Introduction: Oral phosphate binders are the main stay of treatment of hyperphosphatemia. Adherence rates to ferric citrate, a recently approved phosphate binder, are unknown. Methods: We conducted a post‐hoc analysis to evaluate whether adherence rates were different for ferric citrate vs. active control in 412 subjects with end stage kidney disease (ESKD) who were randomized to ferric citrate vs. active control (sevelamer carbonate and/or calcium acetate). Adherence was defined as percent of actual number of pills taken to total number of pills prescribed. Findings: There were no significant differences in baseline characteristics including gender, race/ethnicity, and age between the ferric citrate and active control groups. Baseline phosphorus, calcium, and parathyroid hormone levels were similar. Mean (SD) adherence was 81.4% (17.4) and 81.7% (15.9) in the ferric citrate and active control groups, respectively (P = 0.88). Adherence remained similar between both groups after adjusting for gender, race/ethnicity, age, cardiovascular disease (CVD), and diabetic nephropathy (mean [95% CI]: 81.4% [78.2, 84.6] and 81.5% [77.7, 85.2] for ferric citrate and active control, respectively). Gender, race/ethnicity, age, and diagnosis of diabetic nephropathy did not influence adherence to the prescribed phosphate binder. Subjects with CVD had lower adherence rates to phosphate binder; this was significant only in the active control group. Discussion: Adherence rates to the phosphate binder, ferric citrate, were similar to adherence rates to active control. Similar adherence rates to ferric citrate are notable since tolerance to active control was an entry criteria and the study was open label. Gender, race/ethnicity, nor age influenced adherence. 相似文献