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71.
Protein adsorption is usually regarded as the main reason for filter fouling in sterile filtration of protein formulations. To achieve a better insight into this phenomenon, protein adsorption was studied during filtration of stabilized bovine serum albumin (BSA) and γ-globulin formulations through 0.2-µm microfilter membranes by inverse liquid chromatography (ILC). Adsorption processes can be studied with this method by measurement of breakthrough curves. The change of the concentration in the fluid phase is measured with high accuracy by an inline UV-detector.  相似文献   
72.
Actually, most of the electric energy is being produced by fossil fuels and great is the search for viable alternatives. The most appealing and promising technology is photovoltaics. It will become truly mainstream when its cost will be comparable to other energy sources. One way is to significantly enhance device efficiencies, for example by increasing the number of band gaps in multijunction solar cells or by favoring charge separation in the devices. This can be done by using cells based on nanostructured semiconductors. In this paper, we will present ab-initio results of the structural, electronic and optical properties of (1) silicon and germanium nanoparticles embedded in wide band gap materials and (2) mixed silicon-germanium nanowires. We show that theory can help in understanding the microscopic processes important for devices performances. In particular, we calculated for embedded Si and Ge nanoparticles the dependence of the absorption threshold on size and oxidation, the role of crystallinity and, in some cases, the recombination rates, and we demonstrated that in the case of mixed nanowires, those with a clear interface between Si and Ge show not only a reduced quantum confinement effect but display also a natural geometrical separation between electron and hole.  相似文献   
73.
Generating electricity from waves is predicted to be a new source of renewable energy conversion expanding significantly, with a global potential in the range of wind and hydropower. Several wave power techniques are on the merge of commercialisation, and thus evoke questions of environmental concern. Conservation matters are to some extent valid independent of technique but we mainly focus on point absorbing linear generators. By giving examples from the Lysekil project, run by Uppsala University and situated on the Swedish west coast, we demonstrate ongoing and future environmental studies to be performed along with technical research and development. We describe general environmental aspects generated by wave power projects; issues also likely to appear in Environmental Impact Assessment studies. Colonisation patterns and biofouling are discussed with particular reference to changes of the seabed and alterations due to new substrates. A purposeful artificial reef design to specially cater for economically important or threatened species is also discussed. Questions related to fish, fishery and marine mammals are other examples of topics where, e.g. no-take zones, marine bioacoustics and electromagnetic fields are important areas. In this review we point out areas in which studies likely will be needed, as ventures out in the oceans also will give ample opportunities for marine environmental research in general and in areas not previously studied. Marine environmental and ecological aspects appear to be unavoidable for application processes and in post-deployment studies concerning renewable energy extraction. Still, all large-scale renewable energy conversion will cause some impact mainly by being area demanding. An early incorporation of multidisciplinary and high quality research might be a key for new ocean-based techniques.  相似文献   
74.
Conventional independent component analysis (ICA) monitoring methods extract the feature information of process data by selecting more important independent components (ICs), which discard a small part of ICs that may contain useful information for faults, leading to unsatisfactory monitoring results. However, when the number of sampling points is greater than that of process variables, the ICA monitoring model does not work well. To address the aforementioned problems, a novel monitoring method, multiphase enhanced high-order information extraction (MEHOIE), is proposed in this paper. The entire production process was first divided into several steady phases and transition phases by the affinity propagation (AP) phase partitioning method. The enhanced high-order information extraction (EHOIE) model was then built in each phase for fault monitoring. Finally, the algorithm was applied in the penicillin simulation platform and industrial microbial pharmaceutical process. The flexibility and superiority of this algorithm were verified by comparing it with other conventional methods.  相似文献   
75.
Induction of plant chemical defenses in response to insect feeding may be localized to the site of damage or expressed systemically, mediated by signal transduction throughout the plant. Such systemic induction processes have been widely investigated in plants with single stems, but rarely in clonal plants comprised of multiple ramets with vascular connections. For a clonal tree species such as trembling aspen (Populus tremuloides Michx), integration of induced defense within clones could be adaptive, as clones are spatially extensive and susceptible to outbreak herbivores. We used pairs of aspen saplings with shared roots, replicated from three genotypes, to determine whether defense-induction signals are communicated within clones. One ramet in each pair was subjected to a damage treatment (feeding by Lymantria dispar, followed by mechanical damage), and subsequent changes in leaf defensive chemistry were measured in both ramets. Responses to damage varied by defense type: condensed tannins (CTs) increased in damaged ramets but not in connected undamaged ramets, whereas salicinoid phenolic glycosides (SPGs) were not induced in any ramets. Genotypes varied in their levels of CTs, but not in their levels of SPGs, and responded similarly to damage treatment. These results suggest that, even with both vascular and volatile information available, young aspen ramets do not induce defenses based on signals or metabolites from other ramets. Thus, unlike other clonal plant species, aspen do not appear to coordinate defense induction within clones. Lack of coordinated early induction in aspen may be related to the function of CTs in tolerance, rather than resistance.  相似文献   
76.
Neuromuscular electrical stimulation (NMES) has previously been used to activate the musculature of the lower leg and increase venous return to the heart. However, there is little evidence to suggest the superiority of one particular stimulation site over another. In this paper, we aim to reveal the optimal stimulation site on the lower leg in a group of healthy adults. Doppler ultrasound measurements of venous blood volume expelled and peak venous velocity in response to various single and two-channel applications of NMES were taken for each subject. We found that soleus NMES is the most effective single-channel stimulation method, capable of expelling 58.3% of the blood achieved during a voluntary contraction, alternatively soleus plus tibialis posterior stimulation is capable of expelling 76.5%. Based on these and other factors we suggest that the soleus and soleus plus tibialis posterior are the most effective NMES sites for improving venous return.  相似文献   
77.
Using Mycobacterium smegmatis as a rapidly growing host, six mycobacteriophages were isolated from a variety of environmental sources and characterised by restriction endonuclease digestion. All six phages had long, non-contractile tails and isometric heads characteristic of Siphoviridae and were relatively heat-stable up to 72 °C and generally retained infectivity at pH4–pH10 for 60 min. Each individual phage, when tested against M. smegmatis in both growth media and reconstituted milk, typically reduced host numbers by up to 7 logs. When all 6 phages were combined as a cocktail in milk, a strong bactericidal effect on M. smegmatis was observed over 96 h, evidenced by a 9-log reduction in host cell numbers. These results achieved against M. smegmatis, indicate that mycophages may have a potential application as anti-mycobacterial agents when used against more virulent pathogens such as Mycobacterium avium subsp. paratuberculosis, which has been detected in both raw and pasteurised milk.  相似文献   
78.
ABSTRACT

The relationship between gender and water, sanitation and hygiene (WASH) services is an issue for many developing states. This scoping review demonstrates that in Nepal, women bear the major social burden of inadequate WASH services and are under-represented in WASH-related policies and programmes. Four themes emerge: gender and water projects; lack of equal female participation in WASH policy development and implementation; women’s access to water; and menstruation and menstrual hygiene. Major cultural barriers embedded in Nepali society limit women’s access, agency and participation in WASH-related policy and practice.  相似文献   
79.
Particularly in wireless communications, link errors severely affect the quality of the services due to the high error probability and the specific error characteristics (burst errors) in the radio access part of the network. In this work, we show that thorough analysis and appropriate modeling of radio‐link error behavior are essential to evaluate and optimize higher layer protocols and services. They are also the basis for finding network‐aware cross‐layer processing algorithms which are capable of exploiting the specific properties of the link error statistics, such as predictability. This document presents the analysis of the radio link errors based on measurements in live Universal Mobile Telecommunication System (UMTS) radio access networks as well as new link error models originating from that analysis. It is shown that the knowledge of the specific link error characteristics leads to significant improvements in the quality of streamed video by applying the proposed novel network‐ and content‐aware cross‐layer scheduling algorithms. Although based on live UMTS network experience, many of the conclusions in this work are of general validity and are not limited to UMTS only.  相似文献   
80.
Advanced medical treatments involving drug delivery require fully biocompatible materials with the ability to release functional drugs in a time-prolonged way. Ideally, the delivered molecules should be self-contained as chemically homogenous entities to prevent the use of potentially toxic scaffolds or hold matrices. In nature, peptidic hormones are self-stored in protein-only secretory granules formed by the reversible coordination of Zn2+ and histidine residues. Inspired by this concept, an in vitro transversal procedure is developed, analyzed, and comparatively applied for the fabrication of protein-only secretory granules at the microscale. These materials can be produced from any polyhistidine-tagged protein using physiological concentrations of Zn2+ as a potent and versatile glue-like agent. The screening of granules formed by 12 engineered and nonengineered proteins at different Zn2+ concentrations revealed optimal fabrication conditions and the consequent release profiles. Moreover, the functional and structural properties of the delivered protein are fully validated using a drug-targeting protein platform in a mouse model of human colorectal cancer. In summary, short histidine tags allow the packaging of structurally and functionally dissimilar polypeptides, which supports the proposed fabrication method as a powerful protocol extensible to diverse clinical scenarios in which slow protein drug delivery is required.  相似文献   
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