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131.
The magnetic and structural properties of the solid solutions Sr2FexRu1?xO4 (O ? x ? 0.5) have been studied using 57Fe and 99Ru Mőssbauer spectroscopy and other techniques. These phases, which are reported for the first time, have the K2NiF4-type structure with iron and ruthenium distributed at random on the B-site. As the ruthenium is replaced by iron the weakly-metallic conductivity and Pauli paramagnetism of Sr2RuO4 give way to localized-electron behaviour and long-range antiferromagnetic order despite the layer-type structure which is unfavourable for 180° Ru-O-M (M = Fe or Ru) magnetic exchange interactions in three dimensions. For x = 0.1-0.4 the iron is present almost entirely in the +3 oxidation state, but for x = 0.5 appreciable amounts of FeIV are also present, in conjunction with FeIII, RuIV, and RuV. 相似文献
132.
133.
134.
M Varma DL Rudolph M Knuchel WM Switzer KG Hadlock M Velligan L Chan SK Foung RB Lal 《Canadian Metallurgical Quarterly》1995,33(12):3239-3244
Immunoassays based on the highly immunogenic transmembrane protein of human T-cell lymphotropic virus type 1 (HTLV-1) (protein 21c) are capable of detecting antibodies in all individuals infected with HTLV-1 and HTLV-2. However, because of antigenic mimicry with other cellular and viral proteins, such assays also have a large proportion of false-positive reactions. We have recently identified an immunodominant epitope, designated GD21-I located within amino acids 361 to 404 of the transmembrane protein, that appears to eliminate such false positivity. This recombinant GD21-I protein was used in conjunction with additional recombinant HTLV type-specific proteins and a whole virus lysate to develop a modified Western blot (immunoblot) assay (HTLV WB 2.4). The sensitivity and specificity of this assay were evaluated with 352 specimens whose infection status was determined by PCR assay for the presence or absence of HTLV-1/2 proviral sequences. All HTLV-1-positive (n = 102) and HTLV-2-positive (n = 107) specimens reacted with GD21-1 in the HTLV WB 2.4 assay, yielding a test sensitivity of 100%. Furthermore, all specimens derived from individuals infected with different viral subtypes of HTLV-1 (Cosmopolitan, Japanese, and Melanesian) and HTLV-2 (IIa0, a3, a4, IIb1, b4, and b5) reacted with GD21-I in the HTLV WB 2.4 assay. More importantly, HTLV WB 2.4 analysis of 81 PCR-negative specimens, all of which reacted to recombinant protein 21e in the presence or absence of p24 and p19 reactivity in the standard WB assay, showed that only two specimens retained reactivity to GD21-I, yielding an improved test specificity for the transmembrane protein of 97.5%. None of 41 specimens with gag reactivity only or 21 HTLV-negative specimens demonstrated reactivity to GD21-I. In an analysis of additional specimens (n = 169) from different geographic areas for which PCR results were not available, a substantial increase in the specificity of GD21-I detection was demonstrated, with no effect on the sensitivity of GD21-I detection among specimens from seropositive donors. Thus, the highly sensitive, GD21-I-based HTLV WB 2.4 assay eliminates the majority of false-positive transmembrane results, thereby increasing the specificity for serologic confirmation of HTLV-1 and HTLV-2 infections. 相似文献
135.
We describe here one instance of an acute occlusion of an angioplastied LAD coronary artery occurring during a treadmill stress test performed 2 d after the procedure. The occlusion occurred during the recovery period after a reasonably high level of stress was achieved without evidence of ischaemia. Similar instances described in the literature are summarized and discussed. In the light of these data, it might be prudent to avoid early post-PTCA exercise stress testing. 相似文献
136.
D. N. Lal 《Fatigue & Fracture of Engineering Materials & Structures》1993,16(4):419-428
Quantitative predictions of the influence of yield strength and stress ratio, R , on the physically small crack fatigue threshold stress intensity, Δ K 0(s) , are presented. It is shown that at R = 0 to -1, although the threshold stress Δ0 increases, the threshold stress intensity, Δ K 0(s) , decreases with increasing yield strength. Moreover, a lower bound value, Δ K 0(s)(min) is shown to have a constant value, irrespective of the strength and stress ratio. For a given strength, Δ K 0(s) , decreases with increasing R in the range -1 R 0.6 and attains a constant low value for R > 0.6. Predicted values of Δ K 0(s) are in good agreement with experimental data for steels. The formation and length of non-propagating fatigue cracks, a np , are also discussed. The methods suggested for estimating Δ K 0(s) and a np may be found useful in design procedures. 相似文献
137.
Manohar Lal Kaushik 《Information Sciences》1979,19(1):81-90
A new metric, called the class metric, has already been introduced by Sharma and Kaushik. In this paper, we obtain extensions of Hamming sphere packing and Varsharmov-Gilbert-Sacks bounds to codes correcting random errors and bursts with weight constraints under the class metric. 相似文献
138.
139.
Lanthanum-modified lead zirconate titanate (PZT) powder and volatilisable polymethylmethacrylate (PMM) polymer particles have
been used for fabrication of porous sintered ceramics of interconnected porosity varying from 25% to 59%. Sintered ceramics
are converted into piezoelectric PZT-polymer composites by incorporating silicone rubber elastomer followed by electroding
and poling. Influence of the variation of PZT-PMM ratio and sintering temperatures on the open and closed porosity of the
sintered ceramics as well as volume fraction PZT in the composites has been studied and correlated for the optimization of
piezoelectric properties. The PZT-polymer composites possess low density, considerably high piezoelectric voltage coefficient
and considerably lower ageing characteristics and are therefore considered suitable for designing highly sensitive hydrophone
systems. 相似文献
140.
Harbans Lal 《Drug development and industrial pharmacy》1979,5(2):133-149
Tools of Drug Development
Drug development is the foremost objective of most pharmacologists in the pharmaceutical companies and some pharmacologists in the other research institutions. To meet this objective, thousands of new chemical compounds must be evaluated in order to discover one which can be safely employed in the treatment of human illness. Such evaluation requires an enormous number of experimental subjects specially prepared for this purpose. Since use of human patients for initial screening of new chemicals is not feasible one must depend on laboratory animals that can be used repeatedly and extensively. 相似文献
Drug development is the foremost objective of most pharmacologists in the pharmaceutical companies and some pharmacologists in the other research institutions. To meet this objective, thousands of new chemical compounds must be evaluated in order to discover one which can be safely employed in the treatment of human illness. Such evaluation requires an enormous number of experimental subjects specially prepared for this purpose. Since use of human patients for initial screening of new chemicals is not feasible one must depend on laboratory animals that can be used repeatedly and extensively. 相似文献