全文获取类型
收费全文 | 2452篇 |
免费 | 144篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 15篇 |
化学工业 | 767篇 |
金属工艺 | 23篇 |
机械仪表 | 40篇 |
建筑科学 | 117篇 |
矿业工程 | 6篇 |
能源动力 | 52篇 |
轻工业 | 540篇 |
水利工程 | 23篇 |
石油天然气 | 10篇 |
武器工业 | 1篇 |
无线电 | 146篇 |
一般工业技术 | 351篇 |
冶金工业 | 181篇 |
原子能技术 | 9篇 |
自动化技术 | 296篇 |
出版年
2023年 | 46篇 |
2022年 | 132篇 |
2021年 | 178篇 |
2020年 | 43篇 |
2019年 | 58篇 |
2018年 | 66篇 |
2017年 | 72篇 |
2016年 | 95篇 |
2015年 | 85篇 |
2014年 | 94篇 |
2013年 | 179篇 |
2012年 | 147篇 |
2011年 | 182篇 |
2010年 | 137篇 |
2009年 | 122篇 |
2008年 | 122篇 |
2007年 | 108篇 |
2006年 | 85篇 |
2005年 | 76篇 |
2004年 | 76篇 |
2003年 | 65篇 |
2002年 | 65篇 |
2001年 | 20篇 |
2000年 | 29篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 19篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1973年 | 5篇 |
1969年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有2598条查询结果,搜索用时 0 毫秒
91.
Dora Szabo Zsolt Sarszegi Beata Polgar Eva Saghy Adam Nemeth Dora Reglodi Andras Makkos Aniko Gorbe Zsuzsanna Helyes Peter Ferdinandy Robert Herczeg Attila Gyenesei Attila Cziraki Andrea Tamas 《International journal of molecular sciences》2021,22(6)
Acute myocardial infarction (MI) is one of the most common causes of death worldwide. Pituitary adenylate cyclase activating polypeptide (PACAP) is a cardioprotective neuropeptide expressing its receptors in the cardiovascular system. The aim of our study was to examine tissue PACAP-38 in a translational porcine MI model and plasma PACAP-38 levels in patients with ST-segment elevation myocardial infarction (STEMI). Significantly lower PACAP-38 levels were detected in the non-ischemic region of the left ventricle (LV) in MI heart compared to the ischemic region of MI-LV and also to the Sham-operated LV in porcine MI model. In STEMI patients, plasma PACAP-38 level was significantly higher before percutaneous coronary intervention (PCI) compared to controls, and decreased after PCI. Significant negative correlation was found between plasma PACAP-38 and troponin levels. Furthermore, a significant effect was revealed between plasma PACAP-38, hypertension and HbA1c levels. This was the first study showing significant changes in cardiac tissue PACAP levels in a porcine MI model and plasma PACAP levels in STEMI patients. These results suggest that PACAP, due to its cardioprotective effects, may play a regulatory role in MI and could be a potential biomarker or drug target in MI. 相似文献
92.
Amyloids are supramolecular assemblies composed of polypeptides stabilized by an intermolecular beta-sheet core. These misfolded conformations have been traditionally associated with pathological conditions such as Alzheimer’s and Parkinson´s diseases. However, this classical paradigm has changed in the last decade since the discovery that the amyloid state represents a universal alternative fold accessible to virtually any polypeptide chain. Moreover, recent findings have demonstrated that the amyloid fold can serve as catalytic scaffolds, creating new opportunities for the design of novel active bionanomaterials. Here, we review the latest advances in this area, with particular emphasis on the design and development of catalytic amyloids that exhibit hydrolytic activities. To date, three different types of activities have been demonstrated: esterase, phosphoesterase and di-phosphohydrolase. These artificial hydrolases emerge upon the self-assembly of small peptides into amyloids, giving rise to catalytically active surfaces. The highly stable nature of the amyloid fold can provide an attractive alternative for the design of future synthetic hydrolases with diverse applications in the industry, such as the in situ decontamination of xenobiotics. 相似文献
93.
Vig r 6, the cytokinin‐specific binding protein from mung bean (Vigna radiata) sprouts,cross‐reacts with Bet v 1‐related allergens and binds IgE from birch pollen allergic patients’ sera 下载免费PDF全文
94.
Samir Ananou Margarita Garriga Anna Jofré Teresa Aymerich Antonio Gálvez Mercedes Maqueda Manuel Martínez-Bueno Eva Valdivia 《Meat science》2010
The single and combined effects of enterocin AS-48 and high hydrostatic pressure (HHP) on Listeria monocytogenes, Salmonellaenterica, and Staphylococcus aureus was investigated in fuet (a low acid fermented sausage) during ripening and storage at 7 °C or at room temperature. AS-48 (148 AU g−1) caused a drastic 5.5 log cfu g−1 decrease in L. monocytogenes (P < 0.001) and a significant (P < 0.01) inhibition (1.79 logs) for Salmonella at the end of ripening (10 d). After pressurization (400 MPa) and storage Listeria counts remained below 5 cfu g−1 in all fuets containing AS-48 (pressurized or not). HHP alone had no anti-Listeria effect. HHP treatment significantly reduced Salmonella counts, with lowest levels in pressurized fuets with AS-48. S. aureus showed similar growth for all treatments and storage conditions. These results indicate that AS-48 can be applied alone to control L. monocytogenes and combined with HHP treatment to control Salmonella in fuets. 相似文献
95.
Confocal laser scanning microscopy (CLSM) and low-field nuclear magnetic resonance (LF-NMR) relaxometry were combined to characterize microstructural changes and water distribution in fresh and cooked pork during an aging period of 14 days. At day 1 (24 h postmortem) a few muscle fibres, which appear swollen, were observed in both fresh and cooked meat. An identical microstructure was still apparent after 14 days, however, the number of muscle fibres showing distinguished characteristics was found to increase throughout the aging period. Hence, it was apparent that during aging the individual fibres swell and disintegrate at different rates. Development in water-holding capacity (WHC) was followed during the aging period using gravimetric methods, and an increase in the WHC in the fresh meat was observed, which resembled the amount of extramyofibrillar water measured by NMR relaxometry (T22 population). This was consistent with the CLSM images, as a substantial increase in the number of myofibrils that appeared swollen, capable of holding more water, was observed during aging. In the cooked meat the width of the T21c population, reflecting the myofibrillar water in the cooked meat, was seen to decrease during the entire storage period, which corresponds to the development of a more homogeneous structure. In the CLSM data a continuous degradation during the storage period was observed, which could resemble a shift to a more homogeneous structure. Comparison of CLSM of transverse sections of fresh and cooked pork revealed a pronounced shrinkage of muscle fibres upon cooking. This resulted in large gaps between the cooked muscle fibres, which also was visible as shrinkage at the level of the individual myofibrils. This pattern was also reflected in the NMR relaxation data. The cooking-induced shrinkage of the myofibrils occurred concomitantly with a decrease in the amount of intermyofibrillar water within the individual fibre and an increase in the larger extramyofibrillar spaces between fibres, i.e. water is expelled from the myofibrillar matrix upon cooking. Accordingly, the present study demonstrated that the use of CLSM together with NMR relaxometry can provide further information on the relationship between structural characteristics of meat and resultant water distribution. 相似文献
96.
Effect of carbendazim and physicochemical factors on the growth and ochratoxin A production of Aspergillus carbonarius isolated from grapes 总被引:2,自引:0,他引:2
Medina A Mateo R Valle-Algarra FM Mateo EM Jiménez M 《International journal of food microbiology》2007,119(3):230-235
Carbendazim is a systemic fungicide that is commonly used on several crops (tobacco, fruit, vegetables, cereals, etc.). This fungicide is used to control fungal infections in vineyards. It is indicated against Botrytis cinerea, Uncinula necator, Plasmopara viticola and other fungi and can be used either alone or coupled with other fungicides. However, there is a lack of in-depth studies to evaluate its effectiveness against growth of Aspergillus carbonarius isolated from grapes and OTA production. A medium based on red grape juice was used in this study. Preliminary studies were performed at 0.98 a(w) and 25 degrees C using carbendazim concentrations over a wide range (1-2000 ng/ml medium) to control both growth of a strain of A. carbonarius isolated from grape and its ability to produce OTA. As the lag phase increased considerably at levels > 1000 ng/ml of medium, detailed studies were carried out in the range 50-450 ng/ml of medium at 0.98-0.94 a(w) and 20-28 degrees C. Statistical analysis (multifactor ANOVA) of the data revealed that the three factors assayed and the interactions a(w)-carbendazim concentration and a(w)-temperature had significant effects on lag phase duration. The highest lag-times were observed at 0.94 a(w,) 20 degrees C, and with 450 ng carbendazim/ml. The three factors also had significant effects of the growth rate and there was an interaction between a(w) and temperature. The growth rate of A. carbonarius in these cultures is favoured by high water availability and relatively high temperatures. However, addition of carbendazim at the assayed levels did not significantly influenced fungal growth rate. Accumulation of OTA was studied as a function of four factors (the three previously considered, and time). All factors had significant effects on the accumulation of OTA. There were also two significant interactions (a(w)-temperature and temperature-time). On the basis of the results obtained, carbendazim does not increase the lag phase of A. carbonarius except at relatively low a(w) and temperatures. It does not substantially decrease fungal growth rate once growth is apparent but it appears to cause an increase in OTA accumulation in the medium at the doses assayed. Carbendazim, which is widely used against fungal infections in grape, can positively influence OTA production by A. carbonarius in field, which can increase OTA content in grape juices and wines. 相似文献
97.
Primrose J. Boynton Vienna Kowallik Doreen Landermann Eva H. Stukenbrock 《Yeast (Chichester, England)》2019,36(11):657-668
Saccharomyces yeasts are emerging as model organisms for ecology and evolution, and researchers need environmental Saccharomyces isolates to test ecological and evolutionary hypotheses. However, methods for isolating Saccharomyces from nature have not been standardized, and isolation methods may influence the genotypes and phenotypes of studied strains. We compared the effectiveness and potential biases of an established enrichment culturing method against a newly developed direct plating method for isolating forest floor Saccharomyces spp. In a European forest, enrichment culturing was both less successful at isolating Saccharomyces paradoxus per sample collected and less labour intensive per isolated S. paradoxus colony than direct isolation. The two methods sampled similar S. paradoxus diversity: The number of unique genotypes sampled (i.e., genotypic diversity) per S. paradoxus isolate and average growth rates of S. paradoxus isolates did not differ between the two methods, and growth rate variances (i.e., phenotypic diversity) only differed in one of three tested environments. However, enrichment culturing did detect rare Saccharomyces cerevisiae in the forest habitat and also found two S. paradoxus isolates with outlier phenotypes. Our results validate the historically common method of using enrichment culturing to isolate representative collections of environmental Saccharomyces. We recommend that researchers choose a Saccharomyces sampling method based on resources available for sampling and isolate screening. Researchers interested in discovering new Saccharomyces phenotypes or rare Saccharomyces species from natural environments may also have more success using enrichment culturing. We include step-by-step sampling protocols in the supplemental materials. 相似文献
98.
The involvement of nitrate and nitrite in the formation of N-nitrosamines in foods is a matter of great concern. This situation has led to revise the real amount of nitrate and nitrite needed in meat products to exert proper technological and safety activities, and also to extensive research to find alternatives to their use. The present study addresses the possibility of reducing the ingoing amounts of these additives below the legal limits established by the current European regulations. Different concentrations of nitrate and nitrite were tested on Spanish salchichón-type dry fermented sausages concerning their role in the microbiota and volatile profile. Sausages were manufactured with the maximum ingoing amounts established by the EU regulations (150 ppm NaNO3 and 150 ppm NaNO2), a 25% reduction and a 50% reduction; control sausages with no nitrate/nitrite addition were also prepared. The mixtures were inoculated with 5 log cfu/g of Listeria innocua as a surrogate for Listeria monocytogenes. L. innocua numbers in the final product were approximately 1.5 log cfu/g lower in the batch with the maximum nitrate/nitrite concentration when compared to 25 and 50% reduced batches, and about 2 log cfu/g in comparison to the control sausages. The final numbers of catalase-positive cocci were 1 log cfu/g higher in the 50% nitrate/nitrite reduced batch and 2 log cfu/g higher in the control sausages, compared to products manufactured with the maximum nitrate/nitrite concentration. This increase was related to a higher amount of volatile compounds derived from carbohydrate fermentation and amino acid degradation. Sausages with no addition of nitrate/nitrite showed higher amount of volatiles from lipid oxidation. Enterobacteriaceae counts reached detectable values (1-2 log cfu/g) in both nitrate/nitrite reduced sausages and in the control batch, while these organisms were not detected in the batch with the maximum ingoing amount. Nitrate and nitrite exerted a significant effect on the typical microbiota of dry fermented sausages and effectively contributed to control Listeria. These considerations should be taken into account in view of a future restriction in the use of these curing additives. 相似文献
99.
Thomas O.J. Blomfeldt Richard T. Olsson Mohan Menon David Plackett Eva Johansson Mikael S. Hedenqvist 《大分子材料与工程》2010,295(9):796-801
A new way of producing rigid or semi‐rigid foams from vital wheat gluten using a freeze‐drying process is reported. Water/gluten‐based mixtures were frozen and freeze‐dried. Different foam structures were obtained by varying the mixing process and wheat gluten concentration, or by adding glycerol or bacterial cellulose nanofibers. MIP revealed that the foams had mainly an open porosity peaking at 93%. The average pore diameter ranged between 20 and 73 µm; the sample with the highest wheat gluten concentration and no plasticizer had the smallest pores. Immersion tests with limonene revealed that the foams rapidly soaked up the liquid. An especially interesting feature of the low‐wheat‐concentration foams was the “in situ” created soft‐top‐rigid‐bottom foams.
100.
Inside Back Cover: Ancestral Haloalkane Dehalogenases Show Robustness and Unique Substrate Specificity (ChemBioChem 14/2017) 下载免费PDF全文