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81.
采用钛盐光度法测定O3/H2O2系统中的/H2O2,考察了pH值、O3/H2O2摩尔比、钛盐用量和显色时间的影响,确定了最佳的测定条件;通过加标回收率实验和对比实验,证明了该方法的可靠性.结果表明,pH值为3.0、λ=385nm、草酸钛钾浓度2.5mmol·L-1和显色时间8min条件下,H2O2浓度0~45mg·L-... 相似文献
82.
Yunxia Yang Craig M. Brown Chunxia Zhao Alan L. Chaffee Burke Nick Dongyuan Zhao Paul A. Webley Jacob Schalch Jason M. Simmons Yun Liu Jae-Hyuk Her C.E. Buckley Drew A. Sheppard 《Carbon》2011,(4):1305-1317
Ordered microporous carbons containing dispersed platinum nanoparticles were fabricated and chosen as suitable models to investigate micro-structure development and hydrogen transport properties of zeolite-templated carbons. X-ray photoelectron spectroscopy analysis revealed that the enhanced heat of adsorption is related to the narrow micro-channels templated from the zeolite and the presence of certain CO groups on the carbon. The lack of a well-defined and intense rotational transition line and the persistent broad H2 recoil spectrum in neutron scattering results suggests a distribution of binding sites. Most interestingly, hydrogen diffusion occurs on two time scales, consisting of a fast liquid-like jump diffusion on the timescale of picoseconds along with an even faster bulk-like diffusion. The liquid-like motion is characterized by a diffusion constant of (2.1 ± 0.3) × 10−8 m2/s with an activation energy of ca. 77 K; both values indicate somewhat lower mobility than similar dynamics of H2 on nanotubes, activated carbon XC-72, or Grafoil, yet greater mobility than that of bulk liquid. These unusual characteristics for hydrogen in carbons are believed to arise from the network of narrow pores in this zeolite-templated image of the zeolite. In fact, the diffusion constants of the templated carbons are extremely similar to those measured for zeolite 13X. 相似文献
83.
Craig Frear Zhi‐Wu Wang Chenlin Li Shulin Chen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(1):145-152
BACKGROUND: There remain technological deficiencies in the economical anaerobic digestion of the entire flow of flushed dairy manure on farms within cold climates. In order to develop an anaerobic digester tailored for this purpose, this study investigated the distributions of biomass and biogas generated in three particle‐size‐characterized zones of flushed dairy manure. RESULTS: Results demonstrate that comparable biogas generations are equally distributed between the solids and liquid phases of flushed dairy manure, implying that at least 50% of methane generation might be lost when utilizing existing processes that only selectively handle the liquid or solids phases. Microscopic and kinetic studies show that the majority of microorganisms in the manure are attached to the surface of undigested dairy manure fibrous solids. In particular, greater than 70% of acetate‐utilizing methanogens were found closely associated with the indigestible solids. This high microbial affinity to the dairy manure solids phase can be traced back to the selection pressure driven bacterial immobilization mechanism in cattle rumen. CONCLUSION: This study shows that dairy manure fibrous solids have the potential to act as effective natural biomass carriers for high rate and simultaneous methanation of both solids and liquid phases of flushed dairy manure in one digester. Copyright © 2010 Society of Chemical Industry 相似文献
84.
Craig CJ Goodman JL Schepartz A 《Chembiochem : a European journal of chemical biology》2011,12(7):1035-1038
We reported recently that certain β(3) -peptides self-assemble in aqueous solution into discrete bundles of unique structure and defined stoichiometry. The first β-peptide bundle reported was the octameric Zwit-1F, whose fold is characterized by a well-packed, leucine-rich core and a salt-bridge-rich surface. Close inspection of the Zwit-1F structure revealed four nonideal interhelical salt-bridge interactions whose heavy atom-heavy atom distances were longer than found in natural proteins of known structure. Here we demonstrate that the thermodynamic stability of a β-peptide bundle can be enhanced by optimizing the length of these four interhelical salt bridges. Combined with previous work on the role of internal packing residues, these results provide another critical step in the "bottom-up" formation of β-peptide assemblies with defined sizes, reproducible structures, and sophisticated function. 相似文献
85.
The Updated Bottom Up Solution Applied to Atmospheric Pressure Photoionization and Electrospray Ionization Mass Spectrometry 下载免费PDF全文
William Craig Byrdwell 《Journal of the American Oil Chemists' Society》2015,92(11-12):1533-1547
The Updated Bottom Up Solution (UBUS) was recently applied to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAG). This report demonstrates that the UBUS applies equally well to atmospheric pressure photoionization (APPI) MS and to electrospray ionization (ESI) MS. Critical Ratio 1 (CR1), the [MH]+/Σ[DAG]+ or [MNH4]+/Σ[DAG]+ ratio, does not exhibit the same strongly sigmoidal shape as it does by APCI‐MS. CR1 varies more widely for APPI‐MS than by APCI‐MS, having a maximum value of 11.8, indicating a much greater effect of unsaturation on ion ratios in APPI‐MS than APCI‐MS. Critical Ratio 2, the [AA]+/[AB]+ ratio for Type II TAG or [AC]+/([AB]++[BC]+) ratio for Type III TAG, allows quantification of regioisomers of TAG, and shows good agreement for APPI‐MS to regioisomer quantification determined by APCI‐MS. Critical Ratio 3, the [BC]+/[AB]+ ratio for Type III TAG, reveals new trends relating the degree of unsaturation by APPI‐MS, and shows that structural assignments made by ESI‐MS are in good agreement to APCI‐MS data. In addition to providing valuable structural information, the Critical Ratios also constitute a reduced data set that allows APPI‐MS or ESI‐MS mass spectra to be reconstructed when processed through the UBUS. Quantification by APPI‐MS of vitamin D in the gelcaps gave values of 42.90 ± 0.83 μg, or 1716 ± 33 international units, in good agreement with APCI‐MS. 相似文献
86.
Macintosh Katrina A. McDowell Richard W. Wright-Stow Aslan E. Depree Craig Robinson Guy M. 《Nutrient Cycling in Agroecosystems》2021,120(2):121-129
Nutrient Cycling in Agroecosystems - Reducing agriculturally derived diffuse contaminant losses (via non-point sources) from land to water has proven difficult for decades. Owing to the diversity... 相似文献
87.
88.
Fiona A Murphy Anja Schinwald Craig A Poland Ken Donaldson 《Particle and fibre toxicology》2012,9(1):1-15
Background
Little is known of how the toxicity of nanoparticles is affected by the incorporation in complex matrices. We compared the toxic effects of the titanium dioxide nanoparticle UV-Titan L181 (NanoTiO2), pure or embedded in a paint matrix. We also compared the effects of the same paint with and without NanoTiO2.Methods
Mice received a single intratracheal instillation of 18, 54 and 162 μg of NanoTiO2 or 54, 162 and 486 μg of the sanding dust from paint with and without NanoTiO2. DNA damage in broncheoalveolar lavage cells and liver, lung inflammation and liver histology were evaluated 1, 3 and 28 days after intratracheal instillation. Printex 90 was included as positive control.Results
There was no additive effect of adding NanoTiO2 to paints: Therefore the toxicity of NanoTiO2 was reduced by inclusion into a paint matrix. NanoTiO2 induced inflammation in mice with severity similar to Printex 90. The inflammatory response of NanoTiO2 and Printex 90 correlated with the instilled surface area. None of the materials, except of Printex 90, induced DNA damage in lung lining fluid cells. The highest dose of NanoTiO2 caused DNA damage in hepatic tissue 1 day after intratracheal instillation. Exposure of mice to the dust from paints with and without TiO2 was not associated with hepatic histopathological changes. Exposure to NanoTiO2 or to Printex 90 caused slight histopathological changes in the liver in some of the mice at different time points.Conclusions
Pulmonary inflammation and DNA damage and hepatic histopathology were not changed in mice instilled with sanding dust from NanoTiO2 paint compared to paint without NanoTiO2. However, pure NanoTiO2 caused greater inflammation than NanoTiO2 embedded in the paint matrix. 相似文献89.
Cunkui Huang Craig Hawrelechko James Donald Haibo Huang Xiaohui Deng 《American Institute of Chemical Engineers》2020,66(8):e16265
Solvent mass transfer plays a key role in a thermal gravity drainage process involving solvent. The diffusion coefficients of solvent in such a process are not well studied. This article presents the effective diffusion coefficients of solvent in bitumen-saturated sands under high temperature/pressure conditions measured using a CT scanning technique. Experimental results show that the effective diffusion coefficient of n-hexane in bitumen-saturated sands varied with the solvent concentration or with the viscosity of solvent–bitumen mixture (i.e., De ∝ c0.4 or De ∝ μm−0.46). The solvent concentration weighted diffusion coefficient of n-hexane in the bitumen under the condition 160–170°C/1,900 kPa had an order of magnitude of about 10−5 cm2/s for solvent volume concentration less than 0.2. The penetration distance of n-hexane in bitumen-saturated sands depended on the nonlinearity of diffusion and had a value of −2 cm after 1-day diffusion. The stronger the nonlinearity of diffusion, the shorter the penetration distance. 相似文献
90.
Pryor JL Craig SA Swensen T 《Journal of the International Society of Sports Nutrition》2012,9(1):12-7