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991.
Zhongning Shi Junli Xu Zhuxian Qiu Zhaowen Wang Bingliang Gao 《JOM Journal of the Minerals, Metals and Materials Society》2003,55(11):63-65
The superalloys Cu-Ni-Al, Cu-Ni-Fe, and Cu-Ni-Cr were studied as anodes for aluminum electrolysis. The alloys were tested
for corrosion in acidic electrolyte molten salt and for oxidation in both air and oxygen. The results showed that the Cu-Ni-Al
anodes possess excellent resistance to oxidation and corrosion, and the oxidation rates of Cu-Ni-Fe and Cu-Ni-Al anodes were
slower than those of pure copper or nickel. During electrolysis, the cell voltage of the Cu-Ni-Al anode was affected most
by the concentration of alumina in cryolite molten salt. The Cu-Ni-Fe anode exhibited corrosion resistance in electrolyte
molten salt. Comparatively, the Cu-Ni-Cr anode showed poor resistance to oxidation and corrosion. The testing found that further
study is warranted on the use of Cu-Ni-Al and Cu-Ni-Fe as inert alloy anodes.
For more information, contact Zhongning Shi, Northeastern University, School of Materials and Metallurgy, WenhuiRoad No. 3,
Shenynag, Liaoning 110004 China; e-mail znshi@163.com 相似文献
992.
Dong-il Shin François Gitzhofer Christian Moreau 《Journal of Thermal Spray Technology》2007,16(1):118-127
Metal-based thermal barrier coatings (MBTBCs) have been produced using high frequency induction plasma spraying (IPS) of iron-based
nanostructured alloy powders. The study of MBTBCs has been initiated to challenge issues associated with current TBC materials
such as difficult prediction of their “in-service” lifetime. Reliability of TBCs is an important aspect besides the economical
consideration. Therefore, the study of MBTBCs, which should posses higher toughness than the current TBC materials, has been
initiated to challenge the mechanical problems of ceramic-based TBCs (CBTBCs) to create a new generation of TBCs. The thermal
diffusivity (TD) (α) properties of the MBTBCs were measured using a laser flash method, and density (ρ) and specific heat
(C
p) of the MBTBCs were also measured for their thermal conductivity (k) calculation (k = αρ
C
p). 相似文献
993.
Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures 总被引:1,自引:0,他引:1
Larry D. Hefti 《Journal of Materials Engineering and Performance》2004,13(6):678-682
Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications.
Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material
sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB
is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external
gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off”
that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that
were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the
exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect
solutions for titanium SPF/DB aerospace structures.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
994.
995.
The wear resistance of plasma sprayed molybdenum blend coatings applicable to synchronizer rings or piston rings was investigated
in this study. Four spray powders, one of which was pure molybdenum and the others blended powders of bronze and aluminum-silicon
alloy powders mixed with molybdenum powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying.
Microstructural analysis of the coatings showed that the phases formed during spraying were relatively homogeneously distributed
in the molybdenum matrix. The wear test results revealed that the wear rate of all the coatings increased with increasing
wear load and that the blended coatings exhibited better wear resistance than the pure molybdenum coating, although the hardness
was lower. In the pure molybdenum coatings, splats were readily fractured, or cracks were initiated between splats under high
wear loads, thereby leading to the decrease in wear resistance. On the other hand, the molybdenum coating blended with bronze
and aluminum-silicon alloy powders exhibited excellent wear resistance because hard phases such as CuAl2 and Cu9Al4 formed inside the coating. 相似文献
996.
The flame spraying process, which is a common industrial thermal spraying application, has been analyzed by means of three-dimensional
computational fluid dynamics (CFD) simulations. The process used at the Volvo Aero Corporation for the coating of fan and
compressor housings has been modeled. The process uses the Metco 6P torch (Metco, Westbury, NY), which ejects a mixture of
acetylene and oxygen at high speed through a ring of 16 orifices to form the flame. A stream of argon gas flowing through
an orifice in the center of the ring carries a powder of nickel-covered bentonite through the flame to the spray substrate.
The torch is cooled by a flow of air through an outer ring of 9 orifices. The simulation emulated reality closely by including
the individual inlets for fuel, cooling air, and injected particles. The gas combustion was simulated as a turbulent, multicomponent
chemically reacting flow. The standard, two-equation k-ε turbulence model was used. The chemical reaction rates appeared as
source terms in the species transport equations. They were computed from the contributions of the Arrhenius rate expressions
and the Magnussen and Hjertager eddy dissipation model. The first simulations included several intermediate chemical substances
whose predicted concentration agreed favorably with measurements. Later, more simplified simulations incorporated only the
global chemical reaction involving the initial and the final products, with corrections to the thermal properties being made
to account for the missing intermediaries. The gas velocity and temperature fields predicted by the later simulations compared
satisfactorily to those predicted by the earlier, more elaborate, ones. Therefore, the final simulations, which incorporated
injected particles, were conducted employing the simplified model with only the global reaction. An in-house finite difference
code was developed to calculate particle properties. Allowance was made for elliptical shapes, phase changes, and internal
heat transfer with regard to the composite material. The particle velocities and temperatures predicted by the final simulations
compared fairly well with experimental results obtained with the optical DPV2000 system. 相似文献
997.
Vladimir Brailovski Patrick Terriault Sergei Prokoshkin 《Journal of Materials Engineering and Performance》2002,11(6):614-621
Shape memory alloys (SMA) suffer from the same impairing mechanisms experienced during cycling loading by classic alloys.
Moreover, SMA fatigue behavior is greatly influenced by thermomechanical cycling through the zone of thermoelastic phase transformation,
which is the basis of shape memory and superelasticity effects. Since the fatigue resistance of any material can be improved
by an appropriate thermomechanical treatment, in the present work combined differential scanning calorimetry and microhardness
testing were used to determine an optimum annealing temperature for the cold-worked Ni-50.1%Ti alloy. The optimization is
based on the assumption that latent heat of transformation is proportional to the mechanical work generated by SMA upon heating,
while material hardness is related to the yield stress of the material. It is supposed that an optimum trade-off in these
two properties guarantees the best dimensional and functional stability of SMA devices. The level and stability of the mechanical
work generated by the material during low-cycle fatigue testing are considered criteria for the material performance and thus
of the validity of the proposed optimization procedure. 相似文献
998.
以硝酸铋、硝酸铁以及柠檬酸为原料通过化学液相法在普通载玻片、(100)Si片和(100)ITO玻璃上分别制备了不同厚度的BiFeO3薄膜,研究了热处理温度对BiFeO3的形成以及微观形貌的影响.Si片上的薄膜由于与衬底之间的反应,得到纯BiFeO3相热处理温度需低于650℃,而在普通载玻片和ITO玻璃衬底上,525℃到650℃均可以得到结晶良好的纯BiFeO3薄膜.550℃热处理得到的BiFeO3薄膜中的晶粒尺寸大约在7080 nm之间,650℃热处理得到的晶粒尺寸约有140 nm.磁性能测试证明薄膜有弱铁磁性,饱和磁化强度约在7000~9000 A/m. 相似文献
999.
Fe对NiAl金属间化合物光束堆焊层成形及组织结构的影响 总被引:2,自引:0,他引:2
采用X射线衍射、SEM、EDS等分析方法,研究了铁元素对光束堆焊合成NiAl金属间化合物层的成形和组织结构的影响规律。结果表明,光束堆焊镍铝混合粉制备NiAl金属间化合物层时,NiAl的高熔点导致堆焊层成形困难。在镍铝混合粉中加入适量铁粉(11at%~28at%)可以降低堆焊合金体系的熔点、改善堆焊层成形。随着铁粉加入量的增加,堆焊层的稀释率呈现先增加后降低的趋势,过多的铁粉加入量(43at%)将使熔池金属不能润湿母材。铁元素的引入使堆焊层中析出了Fe3Al相,随着堆焊层中含Fe量的增加,Fe3Al的析出量增加,堆焊层的微观组织为NiAl柱状晶和柱状晶间的Fe3Al条状相。 相似文献
1000.
硅钢片"以冷代热"是大势所趋 总被引:2,自引:0,他引:2
概述了硅钢片的生产历史、冷轧硅钢片的优点和国家“以冷代热”的政策,并对目前硅钢片“以冷代热”仍存在的困难进行了分析。 相似文献