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51.
TG Evans W Bonnez HR Soucier T Fitzgerald DC Gibbons RC Reichman 《Canadian Metallurgical Quarterly》1998,39(3):163-173
Criteria for detection of chromosome aberrations by Comparative Genomic Hybridization (CGH) are not standardized and improvement of this part of the analysis is of paramount importance to the applicability of the technique. The aim of this work was to suggest CGH detection criteria that increase the specificity and sensitivity and at the same time include chromosome regions previously excluded from CGH analysis. We analyzed 33 hybridizations with normal DNA and modified our CGH software in order to use a selection of these normal analyses as a model for interpretation of analyses of unknown samples. This approach was successfully tested on 14 samples with known aberrations. 相似文献
52.
Methylation is one of the many post-translational modifications that modulate protein function. Although asymmetric NG,NG-dimethylation of arginine residues in glycine-arginine-rich domains of eucaryotic proteins, catalyzed by type I protein arginine N-methyltransferases (PRMT), has been known for some time, members of this enzyme class have only recently been cloned. The first example of this type of enzyme, designated PRMT1, cloned because of its ability to interact with the mammalian TIS21 immediate-early protein, was then shown to have protein arginine methyltransferase activity. We have now isolated rat and human cDNA orthologues that encode proteins with substantial sequence similarity to PRMT1. A recombinant glutathione S-transferase (GST) fusion product of this new rat protein, named PRMT3, asymmetrically dimethylates arginine residues present both in the designed substrate GST-GAR and in substrate proteins present in hypomethylated extracts of a yeast rmt1 mutant that lacks type I arginine methyltransferase activity; PRMT3 is thus a functional type I protein arginine N-methyltransferase. However, rat PRMT1 and PRMT3 glutathione S-transferase fusion proteins have distinct enzyme specificities for substrates present in both hypomethylated rmt1 yeast extract and hypomethylated RAT1 embryo cell extract. TIS21 protein modulates the enzymatic activity of recombinant GST-PRMT1 fusion protein but not the activity of GST-PRMT3. Western blot analysis of gel filtration fractions suggests that PRMT3 is present as a monomer in RAT1 cell extracts. In contrast, PRMT1 is present in an oligomeric complex. Immunofluorescence analysis localized PRMT1 predominantly to the nucleus of RAT1 cells. In contrast, PRMT3 is predominantly cytoplasmic. 相似文献
53.
This study examines the vulnerability of clinicians to overdiagnose posttraumatic stress disorder (PTSD) when survivors of a traumatic event are involved in litigation. 19 of 22 survivors of a marine disaster were seen by mental health professionals while pursuing personal injury claims and received a PTSD diagnosis that was maintained for more than 6 mo. This yielded an incidence rate for chronic PTSD of no less than 86%, a rate in excess of any previously reported in the literature for any type of trauma. The extraordinary incidence rate appeared to be explained, in part, by crew members' reports of attorney advice and symptom sharing. Clinicians are cautioned not to rely on client's self-reports and to consider postincident factors that may influence these reports when clients are involved in litigation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
54.
Milton J. Rosen 《Journal of the American Oil Chemists' Society》1972,49(5):293-297
Changes in the various structural units present in surfactants strongly affect the interfacial properties shown by these materials.
Such properties as surface tension reduction, micelle formation, wetting, foaming and defoaming, detergency, and dispersion
of solids all show marked changes with variations in both the hydrophilic and hydrophobic portions of the surfactant molecule,
reflecting the processes occurring on a molecular level. Changes in these properties caused by such factors as the length
and nature of the hydrophobic group, branching or unsaturation in the hydrophobic group, the nature of the hydrophilic group
and its position in the molecule, and the presence or absence of an ionic charge are described and explained in terms of the
molecular processes involved.
Presented at the AOCS Short Course, “Update on Detergents and Raw Materials,” Lake Placid, New York, June 1971. 相似文献
55.
Relationship of structure to properties of surfactants. 16. Linear decyldiphenylether sulfonates 总被引:1,自引:0,他引:1
Milton J. Rosen Zhen Huo Zhu Xi Yuan Hua 《Journal of the American Oil Chemists' Society》1992,69(1):30-33
The properties of some well-characterized sodium linear decyldiphenylether (C10DPE)sulfonates have been studied. Among the properties investigated are dynamic and equilibrium surface tension, critical
micelle concentration (CMC), area per molecule at the aqueous solution/air interface, wetting time by the Draves technique,
foaming by the Ross-Miles method, solubilization, and hydrotropy. The decyldiphenylether moiety appears to be equivalent to
a terminally substituted straight alkyl chain of 16 carbon atoms. The trialkyl- and dialkyl-mono-sulfonates have solubilities
of < 0.01 g/dm3 in water, but are readily soluble in hexane. The didecyldiphenyl ether disulfonate (DADS) has a very low CMC value (1.0 ×
10−5 mol dm−3) in aqueous 0.1 N Na+ solution (NaCl), characteristic of surfactants with two hydrophilic and two hydrophobic groups. It also has a much larger
area per molecule at the aqueous solution/air interface than the monodecyldiphenyl-ether monosulfonate (MAMS) and a much higher
surface tension at the CMC. MAMS has a much lower surface tension at a surface age of 1 second (γ1s) than either DADS or the monodecyldiphenylether disulfonate (MADS). In agreement with γ1s and γeq values, wetting times increase in the order: MAMS < DADS < MADS and initial foam heights decrease in the order: MAMS > DADS
> MADS. Solubilization for three water-insoluble surfactants decreases in the order: DADS > MAMS > MADS, while hydrotropy
is most pronounced with the disulfonates. 相似文献
56.
Bithalamic hyperintensity on T2-weighted MR: vascular causes and evaluation with MR angiography 总被引:1,自引:0,他引:1
PURPOSE: To determine whether MR angiography can be used to differentiate between the two vascular causes of bithalamic hyperintensity on T2-weighted MR images: "top of the basilar" artery occlusion and deep cerebral vein thrombosis. METHODS: A retrospective review identified six patients with bithalamic T2 hyperintensity of vascular causes. MR angiography was performed in four patients, MR angiography and conventional angiography in one patient, and conventional angiography in one patient. Data pertaining to clinical presentation and hospital course were collected. MR angiographic techniques were multislab overlapping three-dimensional time-of-flight, 2-D time-of-flight, and 2-D phase-contrast. RESULTS: Three cases of top of the basilar artery occlusion and three cases of deep cerebral vein thrombosis were recognized. In all cases, T2 hyperintensity in a vascular distribution suggested cerebral occlusive disease. Infarction involving the thalami and basal ganglia was present in two cases of deep cerebral vein thrombosis. Infarction of the thalami, mesodiencephalic region, and cerebellar hemispheres was present in two cases of basilar artery occlusion. Bithalamic infarction alone was seen in one case of deep cerebral vein thrombosis and one case of basilar artery occlusion. In the five cases in which MR angiography was used, this technique accurately distinguished the vessels involved (arterial or venous). CONCLUSION: MR angiography is a useful adjunct to MR imaging in the evaluation of bithalamic T2 hyperintensity. It does help distinguish between the two vascular causes: top of basilar artery occlusion and deep cerebral vein thrombosis. 相似文献
57.
58.
Integrins exhibit reversible changes in their ability to bind ligands and these changes enable transient cell adhesion. We recently showed that leukocyte integrin CR3 (complement receptor type three, CD11b/CD18, alpha m beta 2) may be purified in a form that is either capable or incapable of binding soluble, monomeric ligand and that "inactive" CR3 may be rendered capable of binding ligand by addition of an anti-CR3 mAb known as KIM-127 (Cai and Wright, JBC. 270: 14358, 1995). Here, we demonstrate that active CR3 may be rendered inactive by treatment of immobilized receptor with EDTA. EDTA-treated CR3 failed to bind ligand even in the presence of mM Ca2+ and Mg2+, suggesting that EDTA-treatment caused a change in the receptor that is not readily reversed. EDTA-treated receptor did, however, bind ligand upon addition of KIM-127 plus Mg2+ with an affinity (17.8 +/- 4.5 nM) similar to untreated, active receptor (12.5 +/- 4.7 nM). EDTA-treated CR3 thus exhibits the properties of inactive CR3, in which the ligand binding site is cryptic but subject to exposure by KIM-127. A candidate for the cryptic ligand binding site is the I-domain, a Mg2+-binding region in the alpha chain of CR3. We found that monomeric C3bi binds directly to recombinant I-domain in a Mg(2+)-dependent fashion with an affinity of 300 +/- 113 nM. These results thus suggest that CR3 may be inactivated by removing tightly bound divalent cation from a cryptic site in CR3. 相似文献
59.
To show how apertures affect measurements of the circularly polarized components of light scattered to a detector, we develop two methods of averaging the V and I Stokes parameters over a circular aperture that collects light scattered from an optically active sphere. One method uses a two-dimensional numerical integration that is appropriate for small apertures, and the other gives analytical expressions for scattering into a solid angle of any size. We identify the aperture locations that, independent of aperture size, give an average V (and an effective degree of circular polarization) of zero for scattering from an optically inactive sphere and of nonzero for scattering from an optically active sphere. 相似文献
60.
Aspects of the mathematical specialty of topology appear within several seemingly distinct areas of engineering design and engineering design theory. Indeed, the expression topology of a design is often used informally. In this article a primary intent is to demonstrate the diversity of applications of topology within engineering design. A complementary goal is to introduce the engineering design community to topology as a rich, formal, well-established mathematical discipline that may be of value for wider study. Upon reviewing some of these topological applications, it appears that topology holds promise as a basis for formalizing engineering design theory. This article considers topology as a basis for unifying design abstractions. The potential benefit may be the realization of commonalities between design aspects previously considered separately, where each now has its own attendant specialized, expensive analyses. 相似文献