全文获取类型
收费全文 | 10290篇 |
免费 | 785篇 |
国内免费 | 799篇 |
专业分类
电工技术 | 625篇 |
综合类 | 869篇 |
化学工业 | 1037篇 |
金属工艺 | 1308篇 |
机械仪表 | 813篇 |
建筑科学 | 677篇 |
矿业工程 | 506篇 |
能源动力 | 456篇 |
轻工业 | 231篇 |
水利工程 | 214篇 |
石油天然气 | 284篇 |
武器工业 | 73篇 |
无线电 | 653篇 |
一般工业技术 | 1462篇 |
冶金工业 | 642篇 |
原子能技术 | 289篇 |
自动化技术 | 1735篇 |
出版年
2024年 | 11篇 |
2023年 | 122篇 |
2022年 | 200篇 |
2021年 | 287篇 |
2020年 | 276篇 |
2019年 | 252篇 |
2018年 | 245篇 |
2017年 | 290篇 |
2016年 | 305篇 |
2015年 | 362篇 |
2014年 | 614篇 |
2013年 | 703篇 |
2012年 | 594篇 |
2011年 | 737篇 |
2010年 | 539篇 |
2009年 | 648篇 |
2008年 | 561篇 |
2007年 | 689篇 |
2006年 | 604篇 |
2005年 | 550篇 |
2004年 | 488篇 |
2003年 | 414篇 |
2002年 | 321篇 |
2001年 | 265篇 |
2000年 | 245篇 |
1999年 | 236篇 |
1998年 | 224篇 |
1997年 | 184篇 |
1996年 | 153篇 |
1995年 | 150篇 |
1994年 | 135篇 |
1993年 | 86篇 |
1992年 | 74篇 |
1991年 | 54篇 |
1990年 | 54篇 |
1989年 | 51篇 |
1988年 | 39篇 |
1987年 | 25篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1959年 | 2篇 |
1955年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
《Journal of the European Ceramic Society》2020,40(2):341-348
The quasi-ternary TiB2-CrB2-WB2 system has been studied up to 2300 °C by means of hot-pressing, SPS and pressureless dilatometry. Liquid phase is generated by two binary eutectics at the TiB2-WB2 edge at 2230 ± 30 °C (e1) and at the CrB2-WB2 edge at 1965 °C (e2). A large homogeneity range of a (Ti,W,Cr)B2 solid solution has been noticed. A new ternary γ-phase emerges from a critical tie line between (W,Cr,Ti)2B4 and α-(Ti,W,Cr)B2 solid solution at 1950 °C, spreads slightly into both the WB2 and CrB2 direction and decomposes by the peritectic reaction P: γ ⇆ α-(Ti,Cr,W)B2 + (W,Cr,Ti)2B4 + Liquid at 2170 ± 30 °C. γ reacts with the CrB2-WB2-rich liquid according to the transition equilibrium T: δ-(Ti,Cr,W)B2 + (W,Cr,Ti)2B4 ⇆ γ + Liquid at 2050 °C. The γ-phase is characterized by broad 00 l x-ray reflections which implies a layerwise accumulation and differentiation of Cr and W atoms in the basal plane of the AlB2-type structure. 相似文献
42.
《中国有色金属学会会刊》2020,30(2):417-427
To experimentally determine the isothermal sections of Co−Mo−Zn ternary system at 600 and 450 °C, the equilibrated alloy and diffusion couple methods were adopted by using scanning electron microscopy coupled with energy-dispersive spectrometry, X-ray diffractometry and electron probe microanalysis. Experimental results show that there are six three-phase regions on the Co−Mo−Zn isothermal section at 600 °C and nine three-phase regions on the Co−Mo−Zn isothermal section at 450 °C. No ternary compound is found in these two isothermal sections. Both the maximum solubilities of Mo in the Co−Zn compounds (γ-Co5Zn21, γ1-CoZn7, γ2-CoZn13 and β1-CoZn) and that of Zn in ε-Co3Mo are no more than 1.5 at.%. The maximum solubilities of Zn in μ-Co7Mo6 are determined to be 2.1 at.% and 2.7 at.% at 600 and 450 °C, respectively. In addition, the maximum solubilities of Co in MoZn7 and MoZn22 are 0.5 at.% and 4.7 at.% at 450 °C, respectively. 相似文献
43.
Chaonan Wang Yuliang Hu Liudong Xing Quanlong Guan Chunhui Yang Min Yu 《Quality and Reliability Engineering International》2021,37(5):1783-1795
Motivated by real-world applications of satellites and wireless sensor networks, this paper models and evaluates a dynamic k-out-of-n phase-AND mission system (k/n-PAMS). The mission task conducted by a k/n-PAMS involves multiple consecutive phases; the mission is successful as long as the task is successful in any of the phases. Due to factors, such as scheduled maintenance, location changes in task execution during different phases, and resource sharing with other tasks, the total number of available components n for the considered mission task and the required number of working components k may change from phase to phase. In addition, due to varying load and working environments, component failure time distributions are also phase dependent. This paper proposes an analytical modeling approach based on multivalued decision diagrams (MDDs) for assessing reliability of the considered k/n-PAMS. The approach encompasses a new and fast MDD model generation algorithm that considers behaviors of all the mission phases simultaneously based on node labeling. As demonstrated through empirical studies on k/n-PAMSs with different sizes (different numbers of phases and different numbers of system components), the proposed algorithm is more efficient than the traditional phase-by-phase model generation method. 相似文献
44.
45.
《Journal of the European Ceramic Society》2019,39(16):5410-5422
An investigation of the two-component phase diagram of the CaNaPO4- CaKPO4system performed using various analysis techniques is reported. The continuous solid solution series of α-CaMPO4 existing above 700 °C undergoes eutectoid decomposition during cooling to β-CaMPO4-based solid solutions enriched with Na and K, and to an intermediate nonstoichiometric compound with an ideal composition of CaK0.6Na0.4PO4. All three compounds exhibit significant volumetric effects associated with first-order phase transitions, with positive volume changes under cooling for the intermediate compound. Increased K content in ceramics based on CaKyNa1-yPO4 compositions enhances the strength properties of those ceramics, including their fracture toughness, which is associated with increased density. Increased K content also has a smaller effect of inducing phase transformations accompanied by strong volume changes. 相似文献
47.
《Ceramics International》2022,48(1):855-863
MgAlON transparent ceramic was prepared via pressureless sintering and post hot isostatic pressing. The in-line transmittance of MgAlON ceramic exceeds 80% in the range 0.39–4.67 μm, and the ceramic was fully dense with average grain sizes ~55 μm. The mechanical properties at the grain boundary (GB) and the center of the grain (CG) of MgAlON ceramic was investigated by nanoindentation at forces of 1 × 102–3 × 105 μN. The results indicated that the hardness values of MgAlON ceramic were sensitive to the testing forces and measurements position. The hardness at GB zone was lower than that at CG zone, which was probably ascribed to weaker interatomic bonding force in GB area. The Meyer's index of the hardness in GB and CG regions is 1.87 and 1.82, respectively. There is a weaker ISE in GB area of MgAlON as a result of larger plasticity and smaller elasticity. The hardness values of GB and CG regions are ~13.36 GPa and ~13.58 GPa, respectively. 相似文献
48.
O.A. Kornienko O.R. Andrievskaya O.I. Bykov A.V. Samelyuk Yu. M. Bataiev 《Journal of the European Ceramic Society》2021,41(6):3603-3613
According to the results of the samples studied by X-ray diffraction and microstructural analyzes the phase equilibria in the binary La2O3 – Sm2O3 and ternary ZrO2 – La2O3 – Sm2O3 systems were studied. The boundaries of the phase fields of the binary system are specified and an isothermal cross section of the ternary state diagram of the ZrO2 – La2O3 – Sm2O3 system at a temperature of 1500 °C is constructed. No new phases have been identified in the studied systems. It is established that in the ternary system ZrO2 – La2O3 – Sm2O3 at 1500 °C fields of solid solutions on the basis of cubic (F) modification with structure of fluorite type, tetragonal (T) modification of ZrO2, monoclinic (B) modifications of Sm2O3, hexagonal (A) are formed. La2O3, as well as an ordered phase with a structure of the type of pyrochlore Ln2Zr2O7 (Py). The boundaries of the phase fields and the parameters of the unit cells of the formed phases are determined. A characteristic feature of this isothermal cross section is the formation of a continuous series of solid solutions based on the phase of the pyrochlore type La2Zr2O7 (Sm2Zr2O7). The limiting solubility of Sm2O3 in the ordered phase La2Zr2O7 is 16 mol. % along the section Sm2O3- (67 mol.% ZrO2 - 33 mol.% La2O3). The solubility of La2O3 in the solid solution Sm2Zr2O7 is slightly less and is 11 mol. % along the section La2O3- (67 mol.% ZrO2 - 33 mol.% Sm2O3). The isothermal cross-section of the state diagram of the ZrO2 – La2O3 – Sm2O3 system at 1500 °C is characterized by the presence of three three-phase (Py + T + F), (A + Py + B), (Py + F + B) and eight two-phase (A + Py), (B + A), (B + Py), (F + B), (T + F), (Py + T), (F + Py-two) areas. 相似文献
49.
《Current Opinion in Solid State & Materials Science》2022,26(1):100976
In this paper we review the work related to amorphization under mechanical stress. Beyond pressure, we highlight the role of deviatoric or shear stresses. We show that the most recent works make amorphization appear as a deformation mechanism in its own right, in particular under extreme conditions (shocks, deformations under high stresses, high strain-rates). 相似文献
50.