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21.
Accumulator schemes were introduced in order to represent a large set of values as one short value called the accumulator. These schemes allow one to generate membership proofs, that is, short witnesses that a certain value belongs to the set. In universal accumulator schemes, efficient proofs of non-membership can also be created. Li et?al. (Proceedings of applied cryptography and network security—ACNS ’07, LNCS, vol 4521, 2007), building on the work of Camenisch and Lysyanskaya (Advances in cryptology—proceedings of Crypto ’02, LNCS, vol 2442. Springer, Berlin, pp 61–76, 2002), proposed an efficient accumulator scheme, which relies on a trusted accumulator manager. Specifically, a manager that correctly performs accumulator updates. In this work, we introduce the notion of strong universal accumulator schemes, which are similar in functionality to universal accumulator schemes, but do not assume the accumulator manager is trusted. We also formalize the security requirements for such schemes. We then give a simple construction of a strong universal accumulator scheme, which is provably secure under the assumption that collision-resistant hash functions exist. The weaker requirement on the accumulator manager comes at a price; our scheme is less efficient than known universal accumulator schemes—the size of (non)membership witnesses is logarithmic in the size of the accumulated set in contrast to constant in the scheme of Camenisch and Lysyanskaya. Finally, we show how to use strong universal accumulators to solve a problem of practical relevance, the so-called e-Invoice Factoring Problem.  相似文献   
22.
Methamphetamine is, worldwide, one of the most consumed drugs of abuse. One important side effect is neurodegeneration leading to a decrease in life expectancy. The aim of this paper was to check whether the drug affects one of the receptors involved in neurodegeneration/neuroprotection events, namely the adenosine A2A receptor (A2AR). First, we noticed that methamphetamine does not affect A2A functionality if the receptor is expressed in a heterologous system. However, A2AR becomes sensitive to the drug upon complexes formation with the cannabinoid CB1 receptor (CB1R) and the sigma 1 receptor (σ1R). Signaling via both adenosine A2AR and cannabinoid CB1R was affected by methamphetamine in cells co-expressing the two receptors. In striatal primary cultures, the A2AR–CB1R heteromer complex was detected and methamphetamine not only altered its expression but completely blocked the A2AR- and the CB1R-mediated activation of the mitogen activated protein kinase (MAPK) pathway. In conclusion, methamphetamine, with the participation of σ1R, alters the expression and function of two interacting receptors, A2AR, which is a therapeutic target for neuroprotection, and CB1R, which is the most abundant G protein-coupled receptor (GPCR) in the brain.  相似文献   
23.
The discovery of novel intronic variants in the ABCA4 locus has contributed significantly to solving the missing heritability in Stargardt disease (STGD1). The increasing number of variants affecting pre-mRNA splicing makes ABCA4 a suitable candidate for antisense oligonucleotide (AON)-based splicing modulation therapies. In this study, AON-based splicing modulation was assessed for 15 recently described intronic variants (three near-exon and 12 deep-intronic variants). In total, 26 AONs were designed and tested in vitro using a midigene-based splice system. Overall, partial or complete splicing correction was observed for two variants causing exon elongation and all variants causing pseudoexon inclusion. Together, our results confirm the high potential of AONs for the development of future RNA therapies to correct splicing defects causing STGD1.  相似文献   
24.
Leucine-rich repeats containing G protein-coupled receptor 4 (LGR4) is a receptor that belongs to the superfamily of G protein-coupled receptors that can be activated by R-spondins (RSPOs), Norrin, circLGR4, and the ligand of the receptor activator of nuclear factor kappa-B (RANKL) ligands to regulate signaling pathways in normal and pathological processes. LGR4 is widely expressed in different tissues where it has multiple functions such as tissue development and maintenance. LGR4 mainly acts through the Wnt/β-catenin pathway to regulate proliferation, survival, and differentiation. In cancer, LGR4 participates in tumor progression, invasion, and metastasis. Furthermore, recent evidence reveals that LGR4 is essential for the regulation of the cancer stem cell population by controlling self-renewal and regulating stem cell properties. This review summarizes the function of LGR4 and its ligands in normal and malignant processes.  相似文献   
25.
Hydrogels with excellent stiffness, toughness, anti-fatigue, and self-recovery properties are regarded as promising water-containing materials. In this work, a dual physically cross-linked (DPC) sodium alginate (SA)/poly[acrylamide (AAm)-acrylic acid (AAc)-octadecyl methacrylate (OMA)]-Fe3+ hydrogel is reported, which is constructed by hydrophobic association (HA) and ionic coordination (IC). The optimal DPC hydrogel demonstrates excellent mechanical performance: tensile modulus of 0.65 MPa, tensile strength of 3.31 MPa, elongation at break of 1547%, and toughness of 27.8 MJ m–3. SA/P(AAm-AAc-OMA)-Fe3+ DPC hydrogels also exhibit prominent anti-fatigue and self-recovery performance (99.1–109.7% modulus recovery and 90.4–108.9% dissipated energy recovery after resting for 5 min without additional stimuli at ambient temperature) through the reconstruction of reversible physical cross-linking. Some of the SA/P(AAm-AAc-OMA)-Fe3+ DPC hydrogels even exhibit a stretching-induced strengthening effect, which is similar to the performance of muscle—“the more training, the more strength.” Hence, the combination of HA and IC will provide an effective approach to design DPC hydrogels with desirable mechanical performances and a longer service life for wider applications of soft materials.  相似文献   
26.
o-xylene hydrogenation on supported ruthenium catalysts   总被引:1,自引:0,他引:1  
The influence of the support on the surface properties and catalytic activity of finely divided ruthenium catalysts is reported. The catalysts were prepared using an organometallic precursor, Ru(acac)2, and three different supports, Al2O3, TiO2 and SiO2. In order to study the influence of the particle size on the catalytic performance, the effect of the calcination temperature was also evaluated. XPS suggests that the state of ruthenium is essentially Ru0, and chemisorption measurements indicate a decrease in metal dispersion from catalysts supported on Al2O3 > TiO2 > SiO2. The turnover number in the o-xylene hydrogenation showed significant differences depending on the support and on the particle size. Additionally, an increase in the selectivity to cis-dimethylcyclohexane with particle size was observed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
27.
In biomedical informatics, ontologies are considered a key technology for annotating, retrieving and sharing the huge volume of publicly available data. Due to the increasing amount, complexity and variety of existing biomedical ontologies, choosing the ones to be used in a semantic annotation problem or to design a specific application is a difficult task. As a consequence, the design of approaches and tools addressed to facilitate the selection of biomedical ontologies is becoming a priority. In this paper we present BiOSS, a novel system for the selection of biomedical ontologies. BiOSS evaluates the adequacy of an ontology to a given domain according to three different criteria: (1) the extent to which the ontology covers the domain; (2) the semantic richness of the ontology in the domain; (3) the popularity of the ontology in the biomedical community. BiOSS has been applied to 5 representative problems of ontology selection. It also has been compared to existing methods and tools. Results are promising and show the usefulness of BiOSS to solve real-world ontology selection problems. BiOSS is openly available both as a web tool and a web service.  相似文献   
28.
This paper proposes FMAP (Forward Multi-Agent Planning), a fully-distributed multi-agent planning method that integrates planning and coordination. Although FMAP is specifically aimed at solving problems that require cooperation among agents, the flexibility of the domain-independent planning model allows FMAP to tackle multi-agent planning tasks of any type. In FMAP, agents jointly explore the plan space by building up refinement plans through a complete and flexible forward-chaining partial-order planner. The search is guided by h D T G , a novel heuristic function that is based on the concepts of Domain Transition Graph and frontier state and is optimized to evaluate plans in distributed environments. Agents in FMAP apply an advanced privacy model that allows them to adequately keep private information while communicating only the data of the refinement plans that is relevant to each of the participating agents. Experimental results show that FMAP is a general-purpose approach that efficiently solves tightly-coupled domains that have specialized agents and cooperative goals as well as loosely-coupled problems. Specifically, the empirical evaluation shows that FMAP outperforms current MAP systems at solving complex planning tasks that are adapted from the International Planning Competition benchmarks.  相似文献   
29.
The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene‐co‐vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes—melting, transitions, and reactions—all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2015–2025, 2006  相似文献   
30.
Adsorption isotherms of sesame oil in a concentrated miscella system   总被引:2,自引:0,他引:2  
The adsorption of peroxides, unsaturated carbonyls, free fatty acids and carotenoids from unrefined sesame oil on vegetable carbon (5%, w/w) in a miscella system was studied. Three different solvent conditions (hexane/ethanol, 100:0, 95:5 and 75:25, vol/vol), combined in a factorial design with five levels of solvent (0, 10, 20, 30 and 40%, w/w), were used to develop the miscella. Equilibrium adsorption was not achieved during the 100 min of adsorption, mainly because the oil components were involved in oxidation reactions during the adsorption process. However, for a given solvent concentration, adsorption of the oil components showed a significant linear regression on their respective initial concentration in the miscella (Ci). Peroxides and carbonyls showed, at all solvent levels investigated, an affinity for the carbon more independent of their Ci than free fatty acids and carotenoids. In general, at the same Ci, a higher adsorption was achieved as solvent concentration increased. The results indicated that free fatty acid adsorption may depend on competitive adsorption based on molecule hydrophobicity. However, in spite of the higher hydrophobicity of carotenoids, compared with free fatty acids, they might not be competing for the same adsorbing sites. Ethanol showed a prooxidant effect that increased peroxide production during adsorption but did not affect the reaction involved in carbonyl production.  相似文献   
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