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71.
An increasing flow of evidences collected on elementary forms of learning processes in selected animal models evidentiates some mechanisms which can represent the basic cellular principles underlying plastic changes: 1. 5HT and second messengers of nucleotide type (like cAMP) have a pivotal role in the learning process. 2. In almost all short-term learning processes the modifications are subserved by a mechanism of protein phosphorylation. 3. In various animal models the modulation of K+ and Ca2+ channels is the molecular mechanism for learning. Experiments performed in sensory T neuron of the leech indicate that the modulation of Na+/K+ electrogenic pump is one of the fundamental mechanism for learning. 4. In long-term plastic changes, the most important finding is that newly synthesized proteins are formed. 5. In addition to what has been observed in the Aplysia model, where changes in synaptic efficacy represent the basic principles of memory storage, in the leech it has been demonstrated that a molecular machinery present in a single neuron can adapt the activity of the cell to environmental stimuli.  相似文献   
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OBJECTIVES: To create a more suitable payment system for medical rehabilitation, the authors developed a companion classification system to the original functional independence measure-function-related groups (FIM-FRGs), which classify patients having similar lengths of stay in a rehabilitation hospital or inpatient unit. The companion system presented here groups patients according to their gains in functional status during the rehabilitation stay. METHODS: Data from 84,492 patients discharged from 252 rehabilitation facilities in 1992 were provided by the Uniform Data System for Medical Rehabilitation. Classification rules were formed using clinical judgment and a recursive partitioning algorithm. The gain-FRGs system used four predictor variables: (1) diagnosis leading to disability, admission scores on the (2) motor and (3) cognitive subscales of the FIM, and (4) patient age. RESULTS: The gain-FRGs system contained 74 patient groups and explained 21% of the variation in functional gain for patients in a different set of records withheld for validation. CONCLUSIONS: The gain-FRGs system should be considered for prospective payment systems because it gives the provider an incentive to improve patient outcomes, which is missing in a payment system based on FIM-FRGs alone.  相似文献   
74.
Analysis of Caching and Replication Strategies for Web Applications   总被引:3,自引:0,他引:3  
Developers often use replication and caching mechanisms to enhance Web application performance. The authors present a qualitative and quantitative analysis of state-of-the art replication and caching techniques used to host Web applications. Their analysis shows that selecting the best mechanism depends heavily on data workload and requires a careful review of the application's characteristics. They also propose a technique for Web practitioners to compare different mechanisms' performance on their own  相似文献   
75.
Two-hundred and one strains classified under the (Pasteurella) haemolytica-complex isolated from cattle, sheep, deer, pigs, hares and rabbits were investigated by ribotyping. Fifty-nine of these strains were selected for further studies using multilocus enzyme electrophoresis (MEE). A correlation between the clusters identified by ribotyping and MEE was demonstrated and the results furthermore indicated that a genetic basis exists for most clusters previously outlined by the use of quantitative evaluation of phenotypic data. The taxonomic relevance of ornithine decarboxylase and fermentation of L-arabinose, D-sorbitol and glucosides for taxonomic delineation within the (P.) haemolytica-complex was supported. A taxonomic importance was further indicated for ONPG, ONPX, ONPF, meso-inositol, D-xylose, maltose, dextrine and NPG in relation to some of the taxa. Within the porcine taxon 15, however, differences in ornithine decarboxylase did not correspond to genetic clusters. Six lineages were revealed by MEE. Lineage A contained electrophoretic types (ETs) representing biogroups 1, 3A-3H, 8A and 9, indicating a genetic relationship between these groups--an observation which was supported by ribotyping. Lineage B included biogroup 8D, 3 strains from biogroup 10 and a single strain from biogroup 1 and taxon 18/biovar 1. Lineage C contained strains allocated to biogroup 6 from ruminants and the porcine taxon 15. The similarity between these two groups was accentuated by ribotyping. Lineage D and the single isolate in lineage E contained strains allocated to biogroups 7, 10, 8B and 8C, in addition to single strains from biogroups 6 and 9. The same strains were found in the heterogenous ribotype cluster 17. Lineage F contained strains representing the leprine taxon 20 and the ruminant (P.) granulomatis. Ribotyping indicated that the ruminant biogroup 3J was affiliated with both taxon 20 and (P.) granulomatis.  相似文献   
76.
Recently, a new hematopoietic growth factor, stem cell factor, the ligand for the c-kit-proto-oncogene, has been cloned. The gene for this factor or for its receptor are deleted in two well known series of mice mutants which display pleiotropic stem cell defects. Therefore, this factor supposedly plays an important role in stem cell biology. This paper reviews some of the elegant genetic work which led to the discovery of the factor and of its receptor, the biological effects that this factor exerts in the hematopoietic system in normal individuals and in patients with Diamond-Blackfan anemia and speculates on some of its potential clinical applications.  相似文献   
77.
From November 1992 to February 1993, 455 red deer (Cervus elaphus) were surveyed in order to estimate the prevalence of warble fly (Hypoderma actaeon) larvae under the skin of this ungulate species. Material came from Montes de Toledo, Sierra Morena, Sierra de Alcaraz, and Sierras de Cazorla, Segura y Las Villas Natural Park (central and southern Spain). We observed a prevalence of 92%, with a mean +/- SD intensity of 35.7 +/- 41.3 grubs per parasitized host; there was a maximum of 317 larvae per host. No significant differences in prevalence by host sex were found, although significant differences were observed in prevalences among different host age classes. The main location of feeding larvae in deer was in the back tissues.  相似文献   
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AIM: To estimate how many neonates in New Zealand would qualify for extracorporeal membrane oxygenation (ECMO), using both standard published criteria and locally derived criteria. METHODS: Retrospective chart review of all babies with a birth weight over 2000 g admitted to neonatal intensive care in Auckland from June 1990 to June 1993. Ventilation and blood gas indices were calculated for all babies who were ventilated in 100% O2 for more than 4 hours and who met the basic criteria for ECMO (less than 1 week old with no neurological or chromosomal problems). These indices were compared with published ECMO criteria. Using a threshold of an 80% mortality, Auckland criteria for ECMO were derived. RESULTS: Of the published criteria for ECMO, only an oxygenation index of greater than 40 for 4 hours predicted a mortality of more than 80% in our population. From our own findings a PaO2 < 6.5 kPa for 4 hours predicted a mortality of 79%. CONCLUSION: Approximately 19 neonates might qualify for ECMO in New Zealand each year.  相似文献   
80.
The related adhesion focal tyrosine kinase (RAFTK), a recently discovered member of the focal adhesion kinase family, has previously been reported to participate in signal transduction in neuronal cells, megakaryocytes, and B lymphocytes. We have found that RAFTK is constitutively expressed in human T cells and is rapidly phosphorylated upon the activation of the T cell receptor (TCR). This activation also results in an increase in the autophosphorylation and kinase activity of RAFTK. After its stimulation, there was an increase in the association of the src cytoplasmic tyrosine kinase Fyn and the adapter protein Grb2. This association was mediated through the SH2 domains of Fyn and Grb2. RAFTK also co-immunoprecipitates with the SH2 domain of Lck and with the cytoskeletal protein paxillin through its COOH-terminal proline-rich domain. The tyrosine phosphorylation of RAFTK after T cell receptor-mediated stimulation was reduced by the pretreatment of cells with cytochalasin D, suggesting the role of the cytoskeleton in this process. These observations indicate that RAFTK participates in T cell receptor signaling and may act to link signals from the cell surface to the cytoskeleton and thereby affect the host immune response.  相似文献   
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