全文获取类型
收费全文 | 381篇 |
免费 | 18篇 |
专业分类
化学工业 | 130篇 |
金属工艺 | 2篇 |
机械仪表 | 6篇 |
建筑科学 | 7篇 |
能源动力 | 1篇 |
轻工业 | 80篇 |
水利工程 | 3篇 |
无线电 | 16篇 |
一般工业技术 | 48篇 |
冶金工业 | 64篇 |
原子能技术 | 1篇 |
自动化技术 | 41篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 28篇 |
2021年 | 27篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 19篇 |
2014年 | 16篇 |
2013年 | 22篇 |
2012年 | 23篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 17篇 |
2005年 | 6篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 4篇 |
1999年 | 3篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有399条查询结果,搜索用时 0 毫秒
51.
Molini U Traversa D Ceschia G Iorio R Boffo L Zentilin A Capelli G Giangaspero A 《Journal of food protection》2007,70(2):494-499
In order to evaluate the temporal occurrence of Cryptosporidium oocysts in Ruditapes philippinarum clams bred along the northeastern Italian Adriatic coast and molecularly characterize the isolates, 2,160 specimens (180 clams per month) were collected from three clam farms from January to December 2004. Two farms (sites A and B) were located in Venice (Chioggia, Veneto region) and one (site C) in the Marano Lagoons (Friuli Venezia Giulia region). Clams from 36 pools (i.e., one pool of 60 clams per month per site) were subjected to a high-sensitivity seminested PCR assay specific for a 360-bp diagnostic region internal to the Cryptosporidium spp. outer wall protein gene. Positive amplicons were sequenced and analyzed. Cryptosporidium DNA was found in clams from seven pools (sites A and B) during 1 month of sampling at site A and 6 months of sampling at site B, with Cryptosporidium hominis and Cryptosporidium parvum being detected. The expected infection rate of the clams was 0.36%. Site B showed a significantly higher expected infection rate (1.15%) than did the other sites (A = 0.14% and C = 0%). Given its high sensitivity and specificity, this seminested PCR assay can be considered a reliable tool for detecting and distinguishing species within the Cryptosporidium genus. The seasonal pattern of contamination and the related public health risks are of particular concern. 相似文献
52.
Recombinant adeno-associated virus targets passenger gene expression to cones in primate retina 总被引:2,自引:0,他引:2
Mancuso K Hendrickson AE Connor TB Mauck MC Kinsella JJ Hauswirth WW Neitz J Neitz M 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(5):1411-1416
Recombinant adeno-associated virus (rAAV) is a promising vector for gene therapy of photoreceptor-based diseases. Previous studies have demonstrated that rAAV serotypes 2 and 5 can transduce both rod and cone photoreceptors in rodents and dogs, and it can target rods, but not cones in primates. Here we report that using a human cone-specific enhancer and promoter to regulate expression of a green fluorescent protein (GFP) reporter gene in an rAAV-5 vector successfully targeted expression of the reporter gene to primate cones, and the time course of GFP expression was able to be monitored in a living animal using the RetCam II digital imaging system. 相似文献
53.
Raffaella Colombo 《Critical reviews in food science and nutrition》2020,60(5):760-779
AbstractCoffee is reported to be among the most widely consumed beverages in the world and coffee consumption has been associated with reductions in the risk of several chronic diseases. Among its constituents, caffeine represents the most investigated component. The main impact of caffeine on health is associated with the central nervous system, the cardiovascular system, the inflammatory mechanisms, the metabolism of carbohydrates, and the cancer. Current research is devoted to the role of this compound and its analogs or derivatives on neuroinflammation and neurodegenerative disorders, mainly Alzheimer’s Disease and Parkinson’s Disease. However, coffee is also rich in polyphenols, mainly phenolic acids (chlorogenic acids, caffeic acid, ferulic acid), quinic acid, and quercetin. Many aspects still require greater clarification, including the effect of coffee compounds different from caffeine, on several pathologies. This review aimed to provide a comprehensive overview of the potential benefits of decaffeinated coffee constituents, focusing the attention on neurological processes and pathologies, such as mainly memories disorders, Parkinson’s Disease, neurophatic pain disorders, and cerebral ischemia. 相似文献
54.
Nunzia Novizio Raffaella Belvedere Emanuela Pessolano Silvana Morello Alessandra Tosco Pietro Campiglia Amelia Filippelli Antonello Petrella 《International journal of molecular sciences》2021,22(20)
The tumor microenvironment (TME) is a dynamic system where nontumor and cancer cells intercommunicate through soluble factors and extracellular vesicles (EVs). The TME in pancreatic cancer (PC) is critical for its aggressiveness and the annexin A1 (ANXA1) has been identified as one of the oncogenic elements. Previously, we demonstrated that the autocrine/paracrine activities of extracellular ANXA1 depend on its presence in EVs. Here, we show that the complex ANXA1/EVs modulates the macrophage polarization further contributing to cancer progression. The EVs isolated from wild type (WT) and ANXA1 knock-out MIA PaCa-2 cells have been administrated to THP-1 macrophages finding that ANXA1 is crucial for the acquisition of a protumor M2 phenotype. The M2 macrophages activate endothelial cells and fibroblasts to induce angiogenesis and matrix degradation, respectively. We have also found a significantly increased presence of M2 macrophage in mice tumor and liver metastasis sections previously obtained by orthotopic xenografts with WT cells. Taken together, our data interestingly suggest the relevance of ANXA1 as potential diagnostic/prognostic and/or therapeutic PC marker. 相似文献
55.
Jessica Da Gama Duarte Luke T. Quigley Anna Rachel Young Masaru Hayashi Mariko Miyazawa Alex Lopata Nunzio Mancuso Mikio Mikami Andreas Behren Els Meeusen 《International journal of molecular sciences》2021,22(20)
Ovarian cancers include several disease subtypes and patients often present with advanced metastatic disease and a poor prognosis. New biomarkers for early diagnosis and targeted therapy are, therefore, urgently required. This study uses antibodies produced locally in tumor-draining lymph nodes (ASC probes) of individual ovarian cancer patients to screen two separate protein microarray platforms and identify cognate tumor antigens. The resulting antigen profiles were unique for each individual cancer patient and were used to generate a 50-antigen custom microarray. Serum from a separate cohort of ovarian cancer patients encompassing four disease subtypes was screened on the custom array and we identified 28.8% of all ovarian cancers, with a higher sensitivity for mucinous (50.0%) and serous (40.0%) subtypes. Combining local and circulating antibodies with high-density protein microarrays can identify novel, patient-specific tumor-associated antigens that may have diagnostic, prognostic or therapeutic uses in ovarian cancer. 相似文献
56.
The influence of the growth parameters on the photoluminescence (PL) spectra has been investigated for samples with columnar morphology, either with InN columns on original substrates or as free-standing nanowires. Valuable information about band gap and electron concentration was obtained by line shape analysis. Optical band gaps between 730 and 750 meV and electron concentrations of 8 x 10(17) to 6 x 10(18) cm(-3) were derived from the fit of the PL spectra of different samples. The crystalline quality of the wires was investigated by high-resolution transmission electron microscopy. 相似文献
57.
J. W. Beeman F. A. Danevich V. Y. Degoda E. N. Galashov A. Giuliani I. M. Ivanov M. Mancuso S. Marnieros C. Nones G. Pessina E. Olivieri C. Rusconi V. N. Shlegel V. I. Tretyak Y. V. Vasiliev 《Journal of Low Temperature Physics》2012,167(5-6):1021-1028
We present a prototype scintillating bolometer for the search for neutrinoless double β decay of 100Mo, consisting of a single ≈5?g ZnMoO4 crystal operated aboveground in the 20–30?mK temperature range. The scintillation light is read out by two thin Ge bolometers. The phonon signals are collected by NTD Ge thermistors. The ZnMoO4 crystal was grown with an advanced method (low-thermal-gradient Czochralski technique) and after purification of molybdenum. The results are very encouraging: the intrinsic energy resolution of the heat channel is ≈800?eV FWHM, the α/β rejection factor (crucial for background suppression) is better than 99.9% in the region of interest for double β decay (≈3?MeV), and the radiopurity of ZnMoO4 looks substantially improved with respect to previous devices. 相似文献
58.
59.
Biogenic amines are contaminants naturally present in wines. Their occurrence is influenced by several factors including oenological and agricultural practices, grape variety, and geographical origin. For these reasons, they have been chosen as marker to characterize and classify 56 Italian red wines belonging to four protected designations of origin (PDO) from Southern Italy. Principal component analysis and cluster analysis were applied on data obtained by HPLC/RF in order to highlight the natural grouping of samples. Afterward, linear discriminant analysis and partial least squares were used to classify the wines according to their PDO. Biogenic amines are demonstrated to be a reliable and useful marker for the characterization and classification of the four Southern Italian PDOs investigated. Both the linear discriminant analysis (LDA) and the partial least squares discriminant analysis (PLS-DA) achieved 100 % of wines correctly classified and predicted. Therefore, the determination of these compounds in red wines can play an important role in wine quality assessment, by providing information for the prevention of potential detrimental effects on health and for the characterization of PDO labeled wines. 相似文献
60.
Caroprese M Annicchiarico G Schena L Muscio A Migliore R Sevi A 《The Journal of dairy research》2009,76(1):66-73
The experiment used 45 Comisana ewes, divided into 3 groups of 15. The aim was to determine the effects of two different stocking densities and two different housing conditions on welfare, and on production performance of dairy ewes. The stocking densities tested were: high stocking density (1 x 5 m2/ewe, HD group) and low stocking density (3 m2/ewe, LD group); the two housing conditions tested were: ewes housed indoors (LD group, 3 m2/ewe) and ewes allowed to use an outdoor area (LDP group, 3 m2/ewe divided into 1 x 5 m2/ewe indoors and 1 x 5 m2/ewe outdoors). At the beginning of the experiment, and then every 2 months, the cell-mediated immune status of sheep was evaluated. One month after the beginning of the experiment, and 20 d later, the ewes were injected with chicken egg albumin (OVA) to assess their humoural immune responses. Starting from the beginning of the experiment and then monthly, behavioural activities of ewes were monitored using 15-min scans. After lamb weaning, milk yield from individual ewes was measured and milk composition analysed weekly. Housing conditions (low density reared ewes indoors v. low density reared ewes with free access to an outdoor area) affected cell-mediated response, which was higher in LDP than in LD ewes. Concentrations of anti-OVA IgG were mainly influenced by space allowance, with higher antibody titres in LD than in HD ewes throughout the experiment. Both housing conditions and space allowance affected sheep behavioural activities: a greater proportion of LDP ewes displayed standing and drinking behaviours than LD ewes, and a greater proportion of LD ewes was observed walking than HD ewes. Ewes allowed access to the outdoor area had a higher protein content and lower somatic cell count in their milk, whereas reduced space allowance led to a reduction in milk yield and an increase in somatic cell count of milk. Results indicate that both increased space allowance and availability of outdoor area can improve the welfare and production performance of the lactating ewe. 相似文献