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排序方式: 共有2488条查询结果,搜索用时 31 毫秒
941.
洁净钢中的非金属夹杂物(non-metallic inclusion,NMI)主要在炼钢工艺过程中产生,对宏观性能有很大影响。分析NMI可以建立钢铁工艺与性能之间的"桥梁",为洁净钢产品工艺控制及新品研发提供参考依据。综述NMI表征方法,根据样品制备方法将其分为35种。针对尺寸为1~20μm微观夹杂物采用扫描电镜进行自动分析已经成为当前研究应用热点。对NMI表征方法做了简要介绍,并以具体实践举例说明测试结果可以反映炼钢工艺制度(总氧控制),与最终宏观性能(拉拔断丝率)完全对应。该方法可供国内外同行参考。 相似文献
942.
试述残余元素对电炉钢带肋钢筋性能的影响程度,分析其原因,研究由此引起的屈服上点不明显的测试办法,并从废钢管理,冶炼,轧制及检验提出系统控制的经验措施。 相似文献
943.
J. Piekoszewski L. D?browski L. Wali? Z. Werner M. Kopcewicz L. Nowicki J. Stanis?awski 《Vacuum》2007,81(10):1403-1407
Carbon and alloyed steels were subjected to transient treatment using high intensity argon and nitrogen plasma beams. In the former case the pulses induced only the heat effects whereas in the latter—the reactive atoms generated alloying effects. Austenitic phases have been studied with the use of conversion electron Mössbauer spectroscopy. Regularities between the alloying element contents (C, N, Cr) and austenitic phases have been established and discussed. 相似文献
944.
This paper provides a review of the differences between high pH and near-neutral pH stress corrosion cracking of pipeline steels,influencing factors,and mechanisms.The characteristics and historical information on both forms of SCC are discussed.The prospect for research in the future is also presented. 相似文献
945.
Development of an ultra-high-strength low-alloy NiSiCrCoMo steel 总被引:1,自引:0,他引:1
G Malakondaiah M Srinivas J Marthanda Murthy Rama Rao P 《Bulletin of Materials Science》1994,17(1):73-86
An ultra-high-strength low-alloy NiSiCrCoMo steel has been developed. The development work is part of a major programme at
the Defence Metallurgical Research Laboratory in the field of ultra-high-strength, high-fracture-toughness steels. In this
context we undertook investigations to understand the effect of solute additions on the fracture behaviour of Armco iron and
Fe-C alloys. We investigated Fe-Ni, Fe-Co, Fe-Si, Fe-Mo, Fe-C-Ni and Fe-C-Co alloys for mechanical behaviour. The report by
Garrison (1986) on a Fe-C-Ni-Si-Cr alloy was an important pointer to a low-alloy, ultra-high-strength steel with high fracture
toughness. The material we have now arrived at is a Fe-C-Ni-Si-Cr-Co-Mo steel with tensile, impact and fracture toughness
properties matching those of maraging steel 250 grade in tonnage scale melts. 相似文献
946.
947.
Mechanisms for corrosion fatigue crack propagation 总被引:2,自引:0,他引:2
S. A. SHIPILOV 《Fatigue & Fracture of Engineering Materials & Structures》2002,25(3):243-259
ABSTRACT The corrosion fatigue crack growth (FCG) behaviour, the effect of applied potential on corrosion FCG rates, and the fracture surfaces were studied for high‐strength low‐alloy steels, titanium alloys, and magnesium alloys. During investigation of the effect of applied potential on corrosion FCG rates, polarization was switched on for a time period in which it was possible to register the change in the crack growth rate corresponding to the open‐circuit potential and to measure the crack growth rate under polarization. Due to the higher resolution of the crack extension measurement technique, the time rarely exceeded 300 s. This approach made possible the observation of a non‐single mode effect of cathodic polarization on corrosion FCG rates. Cathodic polarization accelerated crack growth when the maximum stress intensity (Kmax) exceeded a certain well‐defined critical value characteristic for a given material‐solution combination. When Kmax was lower than the critical value, the same cathodic polarization, with all other conditions (specimen, solution, pH, loading frequency, stress ratio, temperature, etc.) being equal, retarded or had no influence on crack growth. The results and fractographic observations suggested that the acceleration in crack growth under cathodic polarization was due to hydrogen‐induced cracking (HIC). Therefore, critical values of Kmax, as well as the stress intensity range (ΔK) were regarded as corresponding to the onset of corrosion FCG according to the HIC mechanism and designated as KHIC and ΔKHIC. HIC was the main mechanism of corrosion FCG at Kmax > KHIC (ΔK > ΔKHIC). For most of the material‐solution combinations investigated, stress‐assisted dissolution played a dominant role in the corrosion fatigue crack propagation at Kmax < KHIC (ΔK < ΔKHIC). 相似文献
948.
949.
Cyclic strain hardening has been observed to be markedly sensitive to microstructural changes in microalloyed steels. Two significantly different microstructures - polygonal ferrite grains of average grain size 10–120 μm and acicular ferrite/upper bainite colonies of dimensions 200–625 μm - were examined in order to determine the influence of each on cyclic strain hardening and related properties. Tests were conducted at temperatures between ?150 and 27°C. The cyclic strain hardening exponent, βc, was significantly more sensitive to changes in the size of the polygonal ferrite grains than to changes in the acicular ferrite/upper bainite colony size. 相似文献
950.
Rolling Contact Fatigue(RCF) is a cumulativedamage phenomenon when metals are subjectedto repeated contact stresses. The fomationof pitting on the contact surface is the resultof the rolling contact fatigue. The morphologiesof rolling contact fatigue fracture of the har-dened steels (86CrHoV7, 42CrMo) show that strongresemblance in fractuye mechanisms exists betweenrolling contact fatigue and uni-axial fatigue.Since fatigue striations are hardly observedin hardened steels under uni-axial fatigue,it is interesting to note that the state ofstress in rolling contact fatigue is more favor-able to ductile fractures than in uni-axialfatigue. 相似文献