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71.
This paper describes a new optoelectronic device—an optical transistor that provides power amplification of output visible
radiation. The optical transistor is structurally based on a metallized semiconductor plate with a microchannel gap in the
form of a planar Mach-Zehnder interferometer. A device of the light-light type is controlled by modulating the refractive
index in one arm of the interferometer.
Pis’ma Zh. Tekh. Fiz. 24, 17–21 (January 26, 1998) 相似文献
72.
Automation and Remote Control - The paper considers the problem of constructing a convex subset of the largest area in a nonconvex compact set on the plane as well as the problem of constructing a... 相似文献
73.
Sergey V. Ushakov Alexandra Navrotsky Jean A. Tangeman Katheryn B. Helean 《Journal of the American Ceramic Society》2007,90(4):1171-1176
Aerodynamic levitation combined with laser heating was used to prepare melts in the HfO2 –La2 O3 (–Gd2 O3 ) systems. All melts crystallized upon quenching in oxygen. Hf2 La2 O7 pyrochlore and Gd0.5 Hf0.5 O1.75 fluorite phases were identified. Gd0.5 Hf0.5 O1.75 fluorite was transformed into the pyrochlore structure by annealing at 1450°C. Pyrochlore that crystallized from HfO2 - La2 O3 melts contained 31.6–34.2 mol% La2 O3 . The unit cell parameter increased linearly with La content from 10.736 to 10.789 Å. Drop solution calorimetric experiments were performed in 3Na2 O·4MoO3 melt at 702°C. The enthalpies of formation from the oxides for pyrochlore phases are −107.0±5.0 kJ/mol for Hf2 La2 O7 and −48.8±4.7 kJ/mol for Hf2 Gd2 O7 . The enthalpy of the pyrochlore–fluorite phase transition in Hf2 Gd2 O7 is 23.6±3.1 kJ/mol. 相似文献
74.
Development of monolithic catalysts with low noble metal content for diesel vehicle emission control
Yashnik S. A. Kuznetsov V. V. Ismagilov Z. R. Ushakov V. V. Danchenko N. M. Denisov S. P. 《Topics in Catalysis》2004,30(1-4):293-298
Topics in Catalysis - Monolith washcoated catalysts with potential for diesel emission control have been developed. Two types of catalysts have been prepared for further study: (1) MnO x supported... 相似文献
75.
S.A. Yashnik Z.R. Ismagilov V.V. Kuznetsov V.V. Ushakov V.A. Rogov I.A. Ovsyannikova 《Catalysis Today》2006,117(4):525-535
A synergetic effect in the catalytic activity has been found after palladium introduction in Mn–Al–O systems. The magnitude of the synergetic effect depends on the types of the oxidic manganese species: oxide Mn3O4, spinel (Mn, Mg)[Mn, Al]2O4 or hexaaluminate (Mn, Mg)LaAl11O19. The synergetic effect of Pd and manganese-containing compounds is observed only if palladium is introduced to the low-temperature precursor of the manganese alumina spinel or manganese hexaaluminate. The synergetic effect is not observed when high-temperature samples with formed spinel or hexaaluminate phases are modified with Pd. 相似文献
76.
Development of Monolithic Catalysts with Low Noble Metal Content for Diesel Vehicle Emission Control
S.A. Yashnik V.V. Kuznetsov Z.R. Ismagilov V.V. Ushakov N.M. Danchenko S.P. Denisov 《Topics in Catalysis》2004,(1):293-298
Monolith washcoated catalysts with potential for diesel emission control have been developed. Two types of catalysts have been prepared for further study: (1) MnO
x
supported on granulated -Al2O3, (2) MnO
x
supported on cordierite monolith washcoated with -Al2O3. Both catalysts have been calcined at 500 and 900 °C and subsequently modified by doping with 0.1–1.0 wt% of Pt or Pd. The influence of the concentration of both manganese oxide (0–10 wt%) and noble metals Pt and Pd in the range 0–1.0 wt% on the catalytic activity in methane oxidation has been studied. Comparison of the catalytic activity of MnO
x
/Al2O3 and MnO
x
+ Pt(Pd)/Al2O3 with that of a standard 1 wt%Pt/Al2O3 catalyst shows the existence of a synergetic effect. This effect is more pronounced for the samples calcined at 900 °C. The developed monolithic catalysts MnO
x
+ Pt(Pd)/Al2O3 demonstrate higher activity and thermal stability (up to 900 °C) compared to the commercial monolithic catalyst (TWC's). 相似文献
77.
Evaluation has been performed of compensators generated by means of a computerized three-dimensional treatment planning system that can utilize either digitized slice profiles or CT scans. Two methods of calculating compensator thickness are used: the modified Batho power law (dSAR) method for digitized profiles and the equivalent TAR (eqTAR) method for CT scans. This system not only compensates for patient surface contours but also compensates for internal inhomogeneities. In addition, any required wedging will be incorporated in the compensator generation. This system has been tested for a number of extreme cases with inhomogeneities and sloping contours. Good agreement was obtained between the measured and computer calculated dose profiles especially along the central axis of the beam. A "Profile Uniformity Index" was defined to quantify the goodness of dose compensation in three dimensions. Compensation using this system can achieve good dose uniformity within the target volume in all clinical cases and is definitely an improvement over systems based solely on tissue deficit. 相似文献
78.
AS Herndon 《Canadian Metallurgical Quarterly》1995,14(4):15-29
A large percentage of older Americans are at risk for malnutrition. This puts them at risk for premature institutionalization, creating a financial burden. The objective of this survey was to determine the nutritional health of clients receiving home delivered meals in Lake County, Indiana and the impact that home delivered meals had on them. Nutrition Screening Initiative (NSI) Determine Your Nutritional Health Checklists were mailed to recipients of meals; 58.3% were returned. Twenty-eight percent were found to be at no nutritional risk, 39% at moderate nutritional risk and 33% at high nutritional risk. One-hundred-thirty clients that scored three or more on the "Checklist" were visited by a Registered Dietitian for further screening using the NSI Level I Screen. This screen found many nutritional problems but the fact that the clients did receive home delivered meals decreased the risk. It was determined by the author that 68% of these clients could not function in their own homes without home delivered meals. 相似文献
79.
Technical Physics Letters - An experimental investigation of the multipath propagation of ultrawideband (UWB) microwave chaotic radio pulses in a wireless channel has been carried out. Based on the... 相似文献
80.
Monocytes/macrophages (M/M) and CD4+ T cells are two important targets of human immunodeficiency virus (HIV) infection. Different strains of HIV-1 vary markedly in their abilities to infect cells belonging to the M/M lineage. Macrophagetropic (M-tropic) HIV-1 strains replicate well in primary lymphocytes as well as in primary macrophages; however, they generally infect T-cell lines poorly, if at all. Although promonocytic cell lines such as U937 have been used as in vitro models of HIV-1 infection of M/M, these cell lines are susceptible to certain T-cell-tropic (T-tropic) HIV-1 strains but are resistant to M-tropic HIV-1. In this study, we demonstrate that (i) certain U937 clones ("plus" clones), which are susceptible only to T-tropic HIV-1, become highly susceptible to M-tropic HIV-1 upon differentiation with retinoic acid (RA); (ii) other U937 clones ("minus" clones), which are resistant to both T- and M-tropic HIV-1, remain resistant to both viruses; and (iii) RA treatment induces expression of CCR5, a fusion/entry cofactor for M-tropic HIV-1 in both types of U937 clones, and yet enhances the fusogenicity of the plus clones, but not the minus clones, with M-tropic Env's. These results indicate that the major restriction of M-tropic HIV-1 infection in promonocytic cells occurs at the fusion/entry level, that differentiation into macrophage-like phenotypes renders some of these cells highly susceptible to infection with M-tropic HIV-1, and that CD4 and CCR5 may not be the only determinants of fusion/entry of M-tropic HIV-1 in these cells. 相似文献