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991.
Conclusions Current directions in the quench cooling of steel are following the traditional and a qualitatively new path. For the solution of old problems in the quench cooling of steel, for example, decreasing distortion, it is possible to use new approaches. The development of various forms of jet stream cooling show promise not only in metallurgical, but also in machine manufacturing plants. The widespread use of quench cooling in metallurgical plants will require an economy in the use of the coolant through an increase in the effectiveness of its use along with a simultanous increase in the cooling intensity. The accelerated cooling of steel will vary according to its functional purpose, and therefore the cooling regime used may significantly differ from that found in traditional regimes of martensitic quenching. Quench cooling of steel at supercritical speeds has great potential during which the supposed effect of austenitic "vacancy" quenching occurs.Dnepropetrovsk Metallurgical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 2–6, September, 1989. 相似文献
992.
Yu. M. Lakhtin Ya. D. Kogan D. P. Shashkov L. G. Petrova 《Metal Science and Heat Treatment》1989,31(6):417-421
1. | During nitriding of nickel alloys which contain Ti in the temperature interval from 1000–1200°C for 5–15 h, the conditions are created for the formation of only internal nitriding and the formation of a nitride zone does not occur. These are prerequisites for increased heat resistance. |
2. | In nickel alloys containing a higher concentration of chromium, a zone of internal nitriding of large thickness occurs during the nitriding process. At the most intense levels of nitriding (t=1200°C and =15h) a through saturation of a 1.5-mm-thick sample of high chrome alloy 2 occurs. |
3. | As a result of nitriding nickel alloys which contain additions of titanium, there is an increase in strength due to the formation of dispersed particles of titanium nitride within the matrix. These particles inhibit the high temperature plastic flow. Another factor which increases the heat resistance of these alloys is the solubility of nitrogen in the matrix which increases the recrystallization temperature, and consequently, the high temperature strength. |
4. | In the alloy which contained the greater concentration of Cr, there is a more intense growth of the diffusion layer. On the other hand, the high concentration of Cr, the lower concentration of Ti, and the absence of Co are the reasons there is a lower increase in the heat resistance as a result of nitriding. |
993.
994.
A. A. Uglov I. Yu. Smurov A. G. Gus'kov K. I. Tagirov 《Journal of Engineering Physics and Thermophysics》1989,56(5):569-574
This article examines convective mass transfer of an impurity in a shallow bath of molten metal with allowance for the motion of the fusion front during the laser alloying of metals.Notation r, z,
cylindrical coordinates
- t
time
- Ti
temperature of the liquid (i=1) and solid (i=2) phases
- q(r)
absorbed energy flux
- k
concentration factor
- Tm
melting point
- L
heat of fusion
-
density
- i, i
thermal conductivity and diffusivity
- T0
initial temperature
- ,
absolute and kinematic viscosities of the melt
- vr, vz
projections of the melt velocity on the coordinate axes r and z
- p
pressure
-
surface tension
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 5, pp. 799–805, May, 1989. 相似文献
995.
Monodisperse silica particles of about 0.3m diameter are suspended in methacrylate monomer using a carefully selected dispersant. Many steric dispersants are hydrocarbon chains with a reactive end-group. These are not effective as dispersants for silica in moderately polar solvents, such as esters and the methacrylate monomers. Good dispersion was obtained with a methacrylate polymer terminated by a chlorosilane end group. Settling or centrifugation of these unagglomerated dispersions gives well-packed particle beds. Polymerization of the surrounding monomer produces composite materials with high packing fractions and a high degree of regularity. Moduli and strengths of these composites are reported. 相似文献
996.
I. G. Vaulina S. V. Gusev G. N. Sivkova Yu. V. Spirchenko A. I. Kukshinov N. A. Makhutov S. V. Nikitin G. Kh. Khurshudov 《Strength of Materials》1989,21(1):1-7
1. | The order of the calculated and experimental stresses and the character of their variation at the sections of the unit are in satisfactory agreement. This is applicable to both toroidal and poloidal forces. The experiment confirmed that the section 2-2 of the unit is maximally loaded. |
2. | The maximum divergences between the calculated and experimental data are observed at the section of the unit adjoining the cylinder (2-2) where the aforementioned differences between the model and the actual unit has the strongest effect. The divergences decrease if the supports of the unit on the cylinder flanges are not taken into account in the calculations (these results are drawn in Fig. 5 with dashed lines). |
3. | In accordance with the experiment data, the presence of a gap along the lines 1–2 and 3–4 raises the maximum stress in the model by 30...40% as compared to the same in a variant without the gap (35% according to calculations [2]). |
4. | The divergences between the calculated and experimental values of the displacements of the characteristic points of the unit do not exceed 20%. |
997.
Yu. K. Kovneristyi N. M. Matveeva L. A. Matlakhova 《Metal Science and Heat Treatment》1988,30(11):847-851
Conclusion In alloys of the TiNi-TiCu system prepared in the form of thin tapes by ultrarapid melt cooling the B2-phase, which is unstable towards martensitic transformation B2B19, contains up to 35% Cu, whereas in bulk alloys prepared in the form of an ingot cooled at normal rates it contains about 10% Cu close to the MS. In alloys containing up to 35% Cu there are no untransformed brittle phases preventing development of martensitic transformation throughout the volume of the material. The structure of alloys is quite uniform, particularly those obtained by crystallizing from the amorphous condition, and the grain size of the high-temperature phase is a fraction of a micron. The fine structure of alloys close to a globular at a high cooling rate. Thus, range of practically important alloys of the B2 type with inelastic behavior effects, e.g., the shape memory effect, is considerably expanded.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 38–41, November, 1988. 相似文献
998.
Yu. G. Trofimenkov 《Soil Mechanics and Foundation Engineering》1988,25(1):45-49
Conclusion 1. For clayey soils, it is possible to confirm, using the curves in Fig. 2, the interlinking of the resultant data from the results of penetration and laboratory determinations of the compression modulus and the undrained-shear strength.2. For sandy soils, it is possible to determine with reliability the angle from Fig. 3 for different penetration depths and different values of q.Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 28–30, January–February, 1978. 相似文献
999.
1000.