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991.
Prediction of adipose tissue composition using raman spectroscopy: Average properties and individual fatty acids 总被引:5,自引:2,他引:3
Raman spectroscopy has been used for the first time to predict the FA composition of unextracted adipose tissue of pork, beef,
lamb, and chicken. It was found that the bulk unsaturation parameters could be predicted successfully [R
2=0.97, root mean square error of prediction (RMSEP)=4.6% of 4 δ], with cis unsaturation, which accounted for the majority of the unsaturation, giving similar correlations. The combined abundance of
all measured PUFA (≥2 double bonds per chain) was also well predicted with R
2=0.97 and RMSEP=4.0% of 4 δ. Trans unsaturation was not as well modeled (R
2=0.52, RMSEP=18% of 4 δ); this reduced prediction ability can be attributed to the low levels of trans FA found in adipose tissue (0.035 times the cis unsaturation level). For the individual FA, the average partial least squares (PLS) regression coefficient of the 18 most
abundant FA (relative abundances ranging from 0.1 to 38.6% of the total FA content) was R
2=0.73; the average RMSEP=11.9% of 4 δ. Regression coefficients and prediction errors for the five most abundant FA were all
better than the average value (in some cases as low as RMSEP=4.7% of 4 δ). Cross-correlation between the abundances of the
minor FA and more abundant acids could be determined by principal component analysis methods, and the resulting groups of
correlated compounds were also well predicted using PLS. The accuracy of the prediction of individual FA was at least as good
as other spectroscopic methods, and the extremely straightforward sampling method meant that very rapid analysis of samples
at ambient temperature was easily achieved. This work shows that Raman profiling of hundreds of samples per day is easily
achievable with an automated sampling system. 相似文献
992.
The citrus leafminer is an important vector of citrus canker in many of the major citrus production areas of the world. (7Z,11Z)-Hexadecadienal was reported as a sex attractant for this insect in the 1980s, based on trap catches during pheromone screening
trials in Japan. However, attempts to reproduce this work in other areas of the world have not been successful. We report
here that (7Z,11Z)-hexadecadienal is only one component of the pheromone, with the other critical component being the analogous trienal, (7Z,11Z,13E)-hexadecatrienal. Both compounds were identified in the effluvia from live female moths by coupled gas chromatography (GC)-electroantennography
using nonpolar and polar GC columns, and the identifications were confirmed by comparisons of mass spectra with those of authentic
standards. Stereoisomers of the two compounds, and a number of analogs, were synthesized to confirm the identifications. In
field trials, neither compound alone was attractive to male moths, but blends of the two were highly attractive, with thousands
of insects being caught per trial. Addition of the isomeric (7Z,11Z,13Z)-hexadecatrienal inhibited attraction to the two-component blend.
Electronic Supplementary Material Supplementary material is available for this article at and accessible for authorized users.
This paper and the preceding paper (Leal et al.) were submitted within a few days of each other. The editors and the authors
agreed that they should be published in tandem. 相似文献
993.
The effects of different grafting content of 4,4′‐methlenebis(phenyl isocyanate)‐modified attapulgite (ATT‐MDI) on thermal and mechanical properties of segmented polyurethane (PU) elastomers were investigated. The ATT‐MDI nanorods with different grafting content were prepared by treating ATT with heat and acid followed by grafting with MDI molecules. MDI‐modified ATT were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy. TGA analysis revealed that at least 30 wt % of MDI was grafted/adsorbed on the surface of ATT following the modification. Three PU/ATT‐MDI nanocomposites were in situ synthesized using ATT with different grafting contents, and the materials were characterized by TEM, thermal analysis, and mechanical testing. The tensile strength and modulus increased with increasing grafting content of MDI molecules, and the crystallinity of soft and hard segments was increased by ATT‐MDI. POLYM. COMPOS., 31:1890–1898, 2010. © 2010 Society of Plastics Engineers. 相似文献
994.
Steven J Adamson Dan Ashley William Hassler Jared Wilburn XQ Gao 《电子工业专用设备》2009,38(7):21-24,41
微电子组装的大部份工艺开发都要求将元件做到更小,以便在尺寸日益缩小的便携式设备上实现更多功能。阐述了大元件的底部填充,即一侧的尺寸超过15mm,底部填充的胶量介于30~50mg。大尺寸晶元的制造工艺要求比现有生产线更大的产能,这就给底部填充点胶带来更大的挑战。大元件的产能超过3000个/h时,需要点胶机点出非常多的胶水。如此多的胶水在出胶前通过点胶阀,这将会带来加热的问题-某些工艺要求出胶前胶水必须要加热。这会对胶点尺寸有影响,因为随着温度的变化,底部填充的胶水黏度也会随之变化,从而轻微影响点出的胶量。从而将影响晶元相邻的“非沾染区”。稳定的温度是点胶稳定性的保证,并且能帮助胶水流进晶元下方同时也有助胶水分离从而更容易喷射出来。从研究中可以观察到:系统温度环境(点胶机内部)对点胶的胶水质量有影响。 相似文献
995.
Hisashi Masui Samantha C. Cruz Shuji Nakamura Steven P. DenBaars 《Journal of Electronic Materials》2009,38(6):756-760
Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in
terms of surface geometry characteristics. The ball–stick model indicates that the semipolar surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations
of epitaxial growth preference for the cation-polarity surface over the surface. The wurtzite surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar
planes. This finding encourages epitaxial growth on the plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with
off-axis crystallographic planes. 相似文献
996.
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is investigated as a transparent cathode to replace indium tin oxide (ITO) in inverted polymer solar cells. Increasing the thickness of the PEDOT:PSS electrode leads to a reduction in transparency and sheet resistance which lowers the photocurrent but increases the fill factor of the solar cells. The offset of photocurrent and fill factor as the thickness is increased leads to a saturation of the power conversion efficiency to 3%. These electrodes were applied to flexible substrates showing similar device performance to glass based devices. Cyclic bending test of these flexible polymer electrodes show improved conversion efficiency retention (92%) when compared to flexible ITO based electrodes (50%) after 300 bend cycles. In addition to using PEDOT:PSS as a cathode replacement for ITO in inverted solar cells, its use as a semi-transparent anode replacement to Ag is also examined. Semi-transparent inverted solar cells fabricated with ITO as the cathode and PEDOT:PSS as the top anode electrode were demonstrated showing efficiencies of 2.51% while replacement of both ITO and Ag with PEDOT:PSS as both the cathode and anode show efficiencies of 0.47%. 相似文献
997.
In this paper, we address the end-to-end rate optimization problem in a wired-cum-wireless network, where CSMA/CA based wireless LANs extend a wired backbone and provide access to mobile users. The objective is to achieve proportional fairness amongst the end-to-end sessions in the network. Since the network contains wireless links whose attainable throughput is a (non-convex and non-separable) function of MAC protocol parameters, the problem requires joint optimization at both the transport and the link layers. A dual-based algorithm is proposed in this paper to solve this cross-layer rate optimization problem. It is implemented in the distributed manner, and works at the link layer to adjust scheduling rates for the wireless links in the basic service sets, and at the transport layer to adjust end-to-end session rates. We prove rigorously that the proposed algorithm converges to the globally optimal rates. Simulation results are provided to support our conclusions. 相似文献
998.
Hydraulic/partitioning tracer tomography for DNAPL source zone characterization: small-scale sandbox experiments 总被引:1,自引:0,他引:1
Dense nonaqueous phase liquids (DNAPL) are prevalent at a large number of sites throughout the world. The variable release history, unstable flow, and geologic heterogeneity make the spatial distribution of DNAPLs complex. This causes difficulties in site remediation contributing to long-term groundwater contamination for decades to centuries. We present laboratory experiments to demonstrate the efficacy of Sequential Successive Linear Estimator (SSLE) algorithm that images DNAPL source zones. The algorithm relies on the fusion of hydraulic and partitioning tracer tomography (HPTT) to derive the best estimate of the K heterogeneity, DNAPL saturation (S(N)) distribution, and their uncertainty. The approach is nondestructive and can be applied repeatedly. Results from our laboratory experiments show that S(N) distributions compare favorably with DNAPL distributions observed in the sandbox but not so with local saturation estimates from core samples. We also found that the delineation of K heterogeneity can have a large impact on computed S(N) distributions emphasizing the importance of accurate delineation of hydraulic heterogeneity. 相似文献
999.
Ewing SA Christensen JN Brown ST Vancuren RA Cliff SS Depaolo DJ 《Environmental science & technology》2010,44(23):8911-8916
During the last two decades, expanding industrial activity in east Asia has led to increased production of airborne pollutants that can be transported to North America. Previous efforts to detect this trans-Pacific pollution have relied upon remote sensing and remote sample locations. We tested whether Pb isotope ratios in airborne particles can be used to directly evaluate the Asian contribution to airborne particles of anthropogenic origin in western North America, using a time series of samples from a pair of sites upwind and downwind of the San Francisco Bay Area. Our results for airborne Pb at these sites indicate a median value of 29% Asian origin, based on mixing relations between distinct regional sample groups. This trans-Pacific Pb is present in small quantities but serves as a tracer for airborne particles within the growing Asian industrial plume. We then applied this analysis to archived samples from urban sites in central California. Taken together, our results suggest that the analysis of Pb isotopes can reveal the distribution of airborne particles affected by Asian industrial pollution at urban sites in northern California. Under suitable circumstances, this analysis can improve understanding of the global transport of pollution, independent of transport models. 相似文献
1000.
Karoline D’Haene Steven Sleutel Stefaan De Neve Donald Gabriels Georges Hofman 《Nutrient Cycling in Agroecosystems》2009,84(3):249-265
Reduced tillage (RT) agriculture is an effective measure to reduce soil loss from soils susceptible to erosion in the short-term
and is claimed to increase the soil organic carbon (SOC) stock. The change in distribution and total SOC stock in the 0–60 cm
layer, the stratification of microbial biomass carbon (MB-C) content in the 0–40 cm layer and the carbon (C) mineralization
in the upper 0–5 cm layer in silt loam soils in Western Europe with different periods of RT agriculture were evaluated. Ten
fields at seven locations, representing the important RT types and maintained for a different number of years, and eight fields
under conventional tillage (CT) agriculture with similar soil type and crop rotation were selected. RT agriculture resulted
in a higher stratification of SOC in the soil profile than CT agriculture. However, the total SOC stock in the 0–60 cm layer
was not changed, even after 20 of years RT agriculture. The MB-C was significantly higher in the 0–10 cm layer under RT agriculture,
even after only 5 years, compared to CT agriculture. The higher SOC and MB-C content in the upper 0–5 cm layer of RT fields
resulted in a higher C mineralization rate in undisturbed soil in the laboratory. Simulating ploughing by disturbing the soil
resulted in inconsistent changes (both lower and higher) of C mineralization rates. A crop rotation with root crops, with
heavy soil disturbance every 2 or 3 years at harvest, possibly limited the anticipated positive effect of RT agriculture in
our research. 相似文献