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991.
Food safety demands calls for new approaches to better understand the safe and hygienic practices of specific sectors in the food supply chain. In the present study, sauerkraut growers were investigated to explore their understanding of food safety and hygiene practices. A combination of quantitative (questionnaire prepared for the study) and qualitative (ten in-depth interviews) methods was used in the study so that topics could be discussed more completely and in greater depth. The results indicated that sauerkraut growers possess a rather good level of knowledge concerning food safety, although some gaps were discovered (e.g., record keeping and the feeling that recording data was an unnecessary burden, inadequate acquaintance with health status requirements, insufficient knowledge of the cabbage production process of food safety professionals, etc.). Some differences were found when comparing the results of the qualitative and quantitative studies. The qualitative analysis highlighted some contradictions (e.g., an attitude toward the production process: “We do not need the HACCP system”; a feeling concerning product safety: “Why the need for data recording?”) and differences between the sauerkraut growers and a professional understanding of good practice guidelines for sauerkraut production. All other determinations concerning food safety knowledge and practices are presented and discussed. The findings can be used as a guide for reorganizing current education programs aimed to improve safe and hygiene practices at the farm level.  相似文献   
992.
裂缝非达西渗流对气井水力压裂设计的影响   总被引:1,自引:0,他引:1  
水力压裂技术是低渗透致密气藏增产的主要手段。在水力压裂裂缝中,气体在裂缝内高速流动产生的非达西渗流使裂缝的有效导流能力和裂缝长度大大减小,从而影响了水力压裂井的产能。在考虑气体非达西渗流的基础上,建立了非达西渗流条件下裂缝有效渗透率和裂缝参数的计算方法,研究了非达西渗流对水力压裂设计参数(裂缝长度、宽度)和产能的影响。结果表明,考虑非达西渗流时的水力压裂必须设计比达西渗流条件下更短和更宽的裂缝;由于裂缝非达西渗流的存在,气井的产能也有较大幅度的降低。考虑非达西渗流进行水力压裂设计和计算时,不能直接用流体在多孔介质或裂缝中的真实渗透率来计算水力压裂气井的产量,而必须用非达西有效渗透率。  相似文献   
993.
Sesamin, a major sesame seed lignan, has diverse biological functions including the modulation of molecular actions in lipid metabolic pathways and reducing cholesterol levels. Vertebrates have different capacities to biosynthesize long-chain PUFA from dietary precursors and sesamin can enhance the biosynthesis of ALA to EPA and DHA in marine teleost. Early juvenile barramundi, Lates calcarifer, were fed for two weeks on diets rich in ALA or SDA derived from linseed or Echium plantagineum, respectively. Both diets contained phytosterols and less cholesterol compared with a standard fish oil-based diet. The growth rates were reduced in the animals receiving sesamin regardless of the dietary oil. However, the relative levels of n-3 LC-PUFA in total lipid, but not the phospholipid, increased in the whole body by up to 25% in animals fed on sesamin with ALA or SDA. Sesamin reduced the relative levels of triacylglycerols and increased polar lipid, and did not affect the relative composition of phospholipid subclasses or sterols. Sesamin is a potent modulator for LC-PUFA biosynthesis in animals, but probably will have more effective impact at advanced ages. By modulating certain lipid metabolic pathways, sesamin has probably disrupted the body growth and development of organs and tissues in early juvenile barramundi.  相似文献   
994.
Structural ceramics are finding application in automotive and truck engines. Poppet valves and valve seats, for example, require resistance to surface damage from repetitive impacts. Grinding and finishing processes can leave microcracks or residual stresses in the surfaces of ceramics which can accelerate surface-initiated degradation processes. A ball-on-inclined plane, repetitive impact testing system has been developed to study the effects of finishing method on surface durability. Tests were performed by repeatedly striking ground alumina and silicon nitride flat specimens with a silicon nitride sphere and measuring the impact damage as a function of the number of strikes. One type of alumina and three types of silicon nitride ceramics were tested. A quantitative impact damage parameter (IDP), based on mechanical stylus profiling data, was developed for use in measuring small amounts of wear. When damage did not extend beyond the depth of valleys in the machined surfaces, the IDP exhibited an excellent linear correlation with the number of impacts of silicon nitride on both silicon nitride and alumina materials. When more extensive damage occurred, a method involving digitizing the area of the contact damage from photomicrographs provided a reasonable correlation with number of impacts. These two methods are compared. Scanning electron microscopy revealed features which can affect the accuracy of impact damage measurement. Implications of the technique are discussed.  相似文献   
995.
The pregnancy-specific glycoproteins (Psg) are secreted hormones encoded by multiple genes in rodents and primates, and are thought to act as immune modulators. The only Psg receptor identified is CD9, through which Psg17 induces cytokine production from macrophages cultured in vitro. We examined temporal and spatial aspects of Psg and CD9 expression during mouse pregnancy to determine whether their expression patterns support a role in immune modulation. Using in situ hybridisation, immunohistochemistry and RT-PCR we found Psg expression in trophoblast giant cells and in the spongiotrophoblast. Psg22 is the predominant Psg family member expressed in giant cells. Detectable Psg is associated predominantly with endothelial cells lining vascular channels in the decidua, rather than with maternal immune cell markers. CD9 expression exhibited partial overlap with Psg, but without exclusive co-localisation. CD9 was observed in decidual cells surrounding early implantation sites, and in the endometrium. However, embryo transfer of wild-type embryos to CD9-deficient females indicates that maternal CD9 is not essential for successful pregnancy.  相似文献   
996.
Tributyltin (TBT) is an organotin compound used since the early 1960s as a biocide in boat antifouling paints. Its use has been linked to a host of negative effects in marine ecosystems including malformations and imposex in Mollusca and acute toxicity in many other aquatic animals. Yet, the consequences of TBT use in freshwaters are largely unknown. Here, for the first time we reveal that TBT may have caused hitherto unsuspected damage to freshwater ecosystems. Through an analysis of dated sediment cores collected from a system of recreationally boated, shallow lakes, we show that first evidence of TBT is associated with a dramatic loss of submerged vegetation and associated diverse animal communities. Cause and effect are difficult to unravel in our study. However, we hypothesize that TBT, through reducing populations of grazing organisms in lakes already affected by eutrophication, promoted the replacement of macrophytes by phytoplankton, ultimately leading to a regime shift in the ecosystem. Our findings may have parallels in freshwater ecosystems all over the world.  相似文献   
997.
Antioxidant and antibacterial activities of freeze-dried and irradiated parsley (Petroselinum crispum) and cilantro (Coriandrum sativum) leaves and stems were determined on methanol and water extracts. The total phenolic content was quantified with the Folin–Ciocalteau reagent. Several mechanisms of potential antioxidant activity of all extracts, including determining relative free radical-scavenging and ferrous ion-chelating activities, as well as reducing power, were examined. Assessment of the total antioxidant activity of all extracts was done using an iron-induced linoleic acid oxidation model system. Antimicrobial activity towards Bacillus subtilis and Escherichia coli by different extracts was assessed by determining cell damage. Total phenolic content varied between parsley and cilantro, leaf and stem, as well as methanol and water extracts. Methanol-derived leaf extracts exhibited significantly (p < 0.05) greater radical-scavenging activity towards both lipid- and water-soluble radicals, which was attributed to the total phenolic content. Ferrous ion-chelating activity was significantly (p < 0.05) greater in the stem methanol extracts, and corresponded to antioxidant activity. Prooxidant activity was a feature of all aqueous extracts and corresponded to the reducing activity of both leaf and stem parts of parsley and cilantro. Bacterial cell damage, resulting in significant (p < 0.05) greater growth inhibition of B. subtilis and E. coli, corresponded to ferrous sequestering activity of methanol-derived stem extracts.  相似文献   
998.
文章对纤维、织物结构、活性染料的化学性质及固色动力学进行了全面研究,优化了藏青色丝光斜纹棉织物的水洗和服用性能;并对增加高效洗涤剂的家庭水洗周期、提高耐汗渍和光照牢度以及减弱折缝摩擦印记的程度进行了研究,将实验试样与标准样作了比较.实验成果对实际生产有很大的指导意义.  相似文献   
999.
PCB, DDT, DDE, dieldrin and total non-polar organohalogen residues have been determined in the blubber-lipid of grey seals (Halichoerus grypus) sampled during the 1972 breeding season (November) at the Farne Islands off the north eastern coast of England. PCBs were analysed by gas-liquid chromatography linked to a chlorine- and carbon-selective microwave plasma detector and total organohalogen residues were determined by microcoulometry.Total organohalogen residues were negatively correlated with blubber thickness and positively correlated with age in males (aged 1 to 24 y) and females (aged 5 to 38 y). However, the correlation of blubber-lipid residue with age in males depended upon the inclusion of immature (aged < 6 y) animals, and in females reflected only a small residue increment. The mean blubber organohalogen concentration of the males was significantly greater than that of the females. PCB and DDT group residue concentrations were significantly correlated.PCB, DDT, DDE and dieldrin were detected in the liver of mother/foetus pairs demonstrating transplacental movement of these residues.The possibility of the condition of the seals at breeding time influencing residue levels and of these residues influencing the health of the population is discussed.  相似文献   
1000.
    
The most important odorants in the crumbs of wheat breads (French-type) prepared according to two different dough recipes using pre-fermentation (crumb I: liquid pre-ferment, containing 0.25% yeast and 1.5% yeast in the final dough; crumb II: soft dough pre-ferment containing 15% yeast and 4.6% yeast in the final dough) were evaluated on the basis of aroma extract dilution analyses. In crumb I, exhibiting the more typical flavour, comparatively higher flavour dilution (FD) factors were found especially for 2-phenylethanol (2-PE) and 3-methyl-butanol (3-MB), while in crumb II the FD factors of methional, 1-octen-3-one, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, butanoic acid and 2- and 3-methylbutanoic acid were higher than in crumb I. Quantitative studies (stable isotope dilution assays) of 2-PE and 3-MB formation, in the liquid pre-ferments containing low yeast concentrations (0.25%) revealed that anaerobic conditions and a fermentation temperature of 35 °C favoured the production of both odorants. Model studies, in which either the 3-MB precursors L-leucine and 3-methylbutanal or the 2-PE precursors L-phenylalanine and phenylacetaldehyde had been added to the pre-ferments, indicated that bakers yeast significantly (15–55%) converted these precursors into the respective odorant.
Intensive Aromastoffe in der Krume von Weißbrot (französische Art)-Einfluß von Vorteigen und Studien zur Bildung wichtiger Geruchsstoffe im Verlauf der Teigherstellung
Zusammenfassung Die wichtigsten Geruchsstoffe in den Krumen von Weißbroten (französische Art), die nach verschiedenen Rezepturen aus vorfermentiertem Teig hergestellt worden waren (Krume I: flüssiger Vorteig mit 0,25% Bäckerhefe und 1,5% Hefe im backfertigem Teig; Krume II: weicher Vorteig mit 15% Hefe und 4,6% Hefe im backfertigen Teig) wurden anhand von Aromaextraktverdün-nungsanalysen bewertet. In Krume I, die das typischere Aroma aufwies, zeigten insbesondere 2-Phenylethanol und 3-Methylbutanol vergleichsweise höhere FD-Faktoren, während in Krume II die FD-Faktoren von Methional, 1-Octen-3-on, 4-Hydroxy-2,5-dimethyl-3(2H)-furanon, Buttersäure sowie 2- und 3-Methylbuttersäure höher waren als in Krume I. Quantitative Untersuchungen (Isotopenver-dünnungsanalysen) zur Freisetzung von 2-Phenylethanol (2-PE) und 3-Methylbutanol (3-MB) in flüssigen Vorteigen mit niedrigen Hefekonzentrationen (0,25%) zeigten, daß anaerobe Bedingungen sowie eine Fermentationstemperatur von 35 °C die Aromastoffbildung begünstigen. Modellstudien, in denen Vorteige zum einen mit L-Leucin und 3-Methylbutanal als Vorläufer von 3-MB, zum anderen mit L-Phenylalanin und Phenylacetaldehyd als Vorläufer des 2-PE angereichert worden waren, ergaben, daß Bäckerhefe diese Vorläufer sehr effektiv (15 bis 55%) zu den Aromastoffen umsetzt.
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