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131.
Creep phenomena in lead-free solders 总被引:3,自引:0,他引:3
A critical review of data on microstructure and creep process activation energy values for a number of lead-free solder alloys
like Sn-Ag; Sn-Bi; Sn-In was conducted. The review revealed a scatter in experimental data, which could not be explained by
the dislocation creep mechanism only, even after the published data was corrected for Young’s modulus temperature dependence.
An analysis of the data implies that possible origin of such a scatter is nucleation, accumulation and further growth of such
internal defects as pores and microcracks during creep. It is shown that these processes may affect the measured steady-state
creep rates, and may be one of the major reasons for the observed scatter in experimental data, and, therefore, must be taken
into consideration in lead-free solder alloys’ creep studies. 相似文献
132.
针对Sn42Bi57Ag1无铅焊料开发出一种低温无铅焊锡膏,着重研究助焊剂中活性剂对焊锡膏润湿性能的影响。以铺展性能作为主要评价指标,通过回流焊接实验,对用于助焊剂的7种有机酸进行了筛选。最终选取了性能较好的甲基丁二酸、己二酸、水杨酸与丁二酸四种有机酸进行正交试验,通过量化分析选取正交试验水平,根据方差分析确定助焊剂中活性剂的最佳组合。结果表明:有机酸的复配能显著改善焊点铺展情况,当甲基丁二酸、己二酸、水杨酸与丁二酸质量比为2∶3∶5∶2时,Sn42Bi57Ag1无铅焊膏的润湿性能优异,焊点铺展率达86.52%。 相似文献
133.
134.
Aditya Kumar Ying Yang Chee C. Wong Vaidhyanathan Kripesh Zhong Chen 《Journal of Electronic Materials》2009,38(1):78-87
The effect of moderate electric current density (1 × 103 to 3 × 103 A/cm2) on the mechanical properties of Ni-P/Sn-3.5Ag/Ni-P and Ni/Sn-3.5Ag/Ni solder joints was investigated using a microtensile
test. Thermal aging was carried out at 160°C for 100 h while the current was passed. The interfacial microstructure and intermetallic
compound (IMC) growth were analyzed. It was found that, at these levels of current density, there were no observable voids
or hillocks. Samples aged at 160°C without current stressing failed mostly inside the bulk solder with significant prior plastic
deformation. The passage of current was found to cause brittle failure of the solder joints and this tendency for brittle
failure increased with increasing current density. Fractographic analysis showed that, in most of the electrically stressed
samples, fracture occurred at the interface region between the solder and the joining metals. The critical current density
that caused brittle fracture was about 2 × 103 A/cm2. Once brittle fracture occurred, the tensile toughness, defined as the energy per unit fractured area, was usually lower
than ~5 kJ/m2, compared with the case of ductile fracture where this value was typically greater than ~9 kJ/m2. When comparing the two types of joint, the brittle failure was found to be more severe with the Ni than with the Ni-P joint.
This work also found that the passage of electric current affects the IMC growth rate more significantly in the Ni than in
the Ni-P joint. In the case of the Ni joint, the Ni3Sn4 IMC at the anode side was appreciably thicker than that formed at the cathode side. However, in the case of electroless Ni-P
metallization, this difference was much smaller. 相似文献
135.
Ja-Young Jung Shin-Bok Lee Ho-Young Lee Young-Chang Joo Young-Bae Park 《Journal of Electronic Materials》2009,38(5):691-699
Anodic dissolution and the electrochemical migration characteristics of eutectic Sn-Pb solder alloy in deaerated 0.001% NaCl
and Na2SO4 solutions were investigated using anodic polarization and water drop tests. Anodic polarization results revealed that a Pb-rich
phase was preferentially ionized in deaerated 0.001% NaCl solution and an Sn-rich phase was predominantly ionized in deaerated
0.001% Na2SO4 solution, which coincides well with the composition of the dendrites formed during water drop tests. X-ray diffraction and
photoelectron spectroscopy results showed that the surface oxide film formed on pure Sn in deaerated 0.001% NaCl solution
is more stable than that formed on pure Sn in deaerated 0.001% Na2SO4 solution. The surface oxide film formed on pure Pb in deaerated 0.001% Na2SO4 solution is more stable than that formed on pure Sn in deaerated 0.001% NaCl solution. Therefore, the quality of the surface
film of eutectic Sn-Pb solder in a chemical environment seems to be critical not only for corrosion resistance, but also for
electrochemical migration resistance. 相似文献
136.
把传统热风整平工艺应用于无铅焊料涂覆,对垂直式和水平式多种设备与材料进行试验比较,研究得出相应的无铅焊料涂覆工艺参数。 相似文献
137.
W. Fredriksz 《Journal of Electronic Materials》2005,34(9):1230-1241
Heat sink very-thin quad flat package no-leads (HVQFN) packages soldered with Sn-3.8Ag-0.7Cu on metallized laminate substrates
have been put to thermal aging. Temperatures from 140°C to 200°C for times up to 30 weeks were applied. The solder joint microstructure
develops intermetallic compound layers and voids within the solder. Due to this, the mechanical reliability of the HVQFN inner
lead solder joints is degraded. The intermetallic layers are of the type (Cu, Y)6Sn5, with Y=Ni, Au or Ni+Au, as well as Cu3Sn, and follow a power law with aging time: X=C·tn, where n=0.4 to 1.9 depending on temperature. The voids within the solder are attributed to Sn depletion of the solder in
favor of the growth of (Cu,Ni)6Sn5. They are more pronounced the less the solder volume is in proportion to the intermetallic diffusion area. The amount of
voids is quantified as a percentage of the residual solder. The time to reach the failure criterion of 50%, i.e., t50%, is related to the absolute temperature according to an Arrhenius equation with an activation energy Ea=0.95 eV. This equation is used for determination of the maximum allowable temperature at a certain required operating lifetime. 相似文献
138.
139.
Interfacial reactions between eutectic SnZn solder and bulk or thin-film Cu substrates are investigated and compared. The
thicknesses of bulk and thin-film Cu substrates are 0.5 mm and 4,000 ?, respectively. Different dominant reaction products
and interfacial microstructures are observed in these two types of interfacial reactions. In the bulk Cu type, the Cu5Zn8 phase is the dominant reaction product under reflow and solid-state annealing. However, the CuZn5 phase becomes the dominant reaction product in the thin-film Cu type. The Cu5Zn8 phase in the bulk Cu type remains as a uniform microstructure after reflow. After solid-state annealing, however, the Cu5Zn8 phase fractures and the Cu6Sn5 and Cu3Sn phases are formed at the Cu5Zn8/Cu interface. The CuZn5 phase in the thin-film Cu type ripens after reflow and the phase morphology is transformed from a uniform layer into separated
scallops. In situ observation of the interfacial microstructure after solid-state annealing reveals that prominent deformation occurs in the
solder region close to the interface in the bulk Cu type. While in the thin-film Cu type, the CuZn5 grain is extruded out of the interface. 相似文献
140.
Encapsulation of lead-free Sn/Zn/Bi solder alloy particles by coating with wax powder for improving oxidation resistance 总被引:2,自引:0,他引:2
Tomohiro Iwasaki Jeong Hwan Kim Shohei Mizuhashi Munetake Satoh 《Journal of Electronic Materials》2005,34(5):647-654
An encapsulation treatment of lead-free Sn/Zn/Bi solder powder was investigated for improving the oxidation resistance. Sn-8mass%Zn-3mass%Bi
alloy particles were coated with a wax (12-hydroxystearic acid) powder by means of a dry mechanical treatment method using
a ball mill. In order to determine the optimum operating conditions of the ball mill in the wax-coating treatments, the compressive
energy required for deforming a single Sn/Zn/Bi alloy particle was measured with an unconfined compression tester and the
mechanical energy applied to the alloy particles in the ball mill was estimated using the results of the compression test.
The optimum operating conditions were determined based on both the applied energy and the flowability of solder pastes, and
the wax-coated alloy particles maintaining the spherical shape were obtained under the conditions. The wettability test and
the solder balling test for the solder pastes containing the wax-coated alloy particles stored at room temperature in air
were carried out to evaluate the oxidation resistance performance. The wax-coated alloy particles had an excellent wettability
compared with the original alloy particles, and the oxidation resistance of the Sn/Zn/Bi solder powder was improved by the
encapsulation treatment. 相似文献