全文获取类型
收费全文 | 608篇 |
免费 | 22篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 252篇 |
金属工艺 | 15篇 |
机械仪表 | 4篇 |
建筑科学 | 24篇 |
能源动力 | 19篇 |
轻工业 | 79篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 86篇 |
冶金工业 | 32篇 |
原子能技术 | 6篇 |
自动化技术 | 86篇 |
出版年
2022年 | 7篇 |
2021年 | 22篇 |
2020年 | 3篇 |
2019年 | 17篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 11篇 |
2015年 | 13篇 |
2014年 | 26篇 |
2013年 | 41篇 |
2012年 | 35篇 |
2011年 | 39篇 |
2010年 | 39篇 |
2009年 | 37篇 |
2008年 | 29篇 |
2007年 | 24篇 |
2006年 | 17篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 12篇 |
2001年 | 11篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有630条查询结果,搜索用时 0 毫秒
11.
Veronika Ozana Karel Hruska Leonardo A. Sechi 《International journal of molecular sciences》2022,23(7)
Civilization factors are responsible for the increasing of human exposure to mycobacteria from environment, water, and food during the last few decades. Urbanization, lifestyle changes and new technologies in the animal and plant industry are involved in frequent contact of people with mycobacteria. Type 1 diabetes is a multifactorial polygenic disease; its origin is conditioned by the mutual interaction of genetic and other factors. The environmental factors and certain pathogenetic pathways are shared by some immune mediated chronic inflammatory and autoimmune diseases, which are associated with triggers originating mainly from Mycobacterium avium subspecies paratuberculosis, an intestinal pathogen which persists in the environment. Type 1 diabetes and some other chronic inflammatory diseases thus pose the global health problem which could be mitigated by measures aimed to decrease the human exposure to this neglected zoonotic mycobacterium. 相似文献
12.
A number of life forms, including seeds, certain nematodes, bacterial and fungal spores, and cysts of certain crustaceans, show an ability to survive desiccation. The present article reviews the literature available on this subject and critically evaluates the evidence for various mechanisms that may be responsible for these phenomena. Specific mechanisms considered include vitrification (glass formation) by sugars and other polyhydroxy compounds that are accumulated by the desiccated structures, specific effects of polyhydroxy compounds on membranes, effect of “compatible solutes” on conformation of key proteins, as well as other biochemical mechanisms.
The article presents potential applications relevant to food technology and to biotechnology and reviews the research required to materialize more effective use of desiccation in food and biopreservation. 相似文献
13.
Thirty randomly selected Aeromonas isolates from food and the environment in Abu Dhabi, United Arab Emirates, were characterized for putative virulence determinants, such as production of cytotoxin, cytotonic toxin, and hemolysin and their capacity to adhere to and invade Henle 407 cells in vitro. Seventy percent of the tested isolates were cytotoxin producers, and 80% were hemolytic. Cytotoxin was produced by 6 of 7 A. hydrophila strains, 6 of 13 A. caviae strains, and 6 of 7 A. veronii bv. sobria strains, mostly from food sources. A. schubertii, A. jandaei, and A. trota also produced both cytotoxin and hemolysin. All of the 30 isolates tested adhered to Henle 407 cells, but none were able to invade the cells, as determined with the in vitro assay. However, no significant correlation of the presence of these putative virulence factors was found among these aeromonad food isolates. 相似文献
14.
15.
Sylwester Mazurek Roman Szostak Agnieszka Kita Alicja Z. Kucharska Anna Sokół-Łętowska Karel Hamouz 《Food Analytical Methods》2017,10(12):3964-3971
The application of vibrational spectroscopy for the determination of total polyphenols content, antioxidant activity, colour parameters, and fat level in chips originated from yellow-, red- and purple-fleshed potato varieties is reported. Raman, infrared (IR) and near-infrared (NIR) spectra of the laboratory-prepared chips were collected. Combining spectral data with the results of reference analyses, partial least squares regression models were built. To characterise and compare the elaborated models, the relative standard errors of prediction were calculated for calibration and validation sets. In the case of total phenolics quantification by Raman/IR/NIR techniques, these errors (%) amounted to 4.0/7.0/7.1 and 6.4/8.5/8.4 for calibration and validation samples, respectively, whereas they were 4.9/7.7/4.8 and 6.6/8.3/6.8 for antioxidant activity. The obtained results demonstrate that both infrared and Raman spectroscopy can effectively replace commonly used extraction methods. It follows that Raman spectroscopy has the highest potential to be adopted for the online potato-derived product analysis. 相似文献
16.
Helena Valentová Miroslav Kašpar Věra Hamplová Karel Bouchal Michal Ilavský Antonín Sikora Daniel Froelich René Muller 《Polymer Bulletin》1997,38(2):219-226
The dynamic mechanical behaviour of random copolymers of LC monomer-1-(hexyloxycarbonyl)ethyl 4-[4-(methacryloyloxy)benzoyloxy]benzoate
(HB) and octyl methacrylate (OMA) was studied in the main transition and flow regions. Even though the aliphatic end groups
of the side chain of HB and OMA are roughly the same, the T
g temperature of poly(HB) is ∼ 80 K higher than that of poly(OMA); this fact is due to the presence of the stiff phenyl benzoate
mesogenic group in the side chain of HB. With increasing content of OMA in the copolymer the superimposed curves of the storage
G′
p and loss G′′
p moduli at a constant temperature shift towards shorter frequencies. It has been shown that this shift is mainly due to an
increase of the free volume in the copolymers with increasing content of OMA. While HB monomer shows liquid crystalline (LC)
properties, its polymer (poly(HB)) and random copolymers with OMA show only isotropic thermal behaviour because no flexible
spacer is present in the side chain of HB which would decouple the main chain and mesogenic group motions. This means that
neither the homopolymer of HB, nor its copolymers with a flexible comonomer retain the LC properties of the starting LC monomer,
HB.
Received: 26 September 1996/Revised: 7 November 1996/Accepted: 7 November 1996 相似文献
17.
Identification of molecular species of various N-acylated bacteriohopanehexol-mannosamides from the thermophilic bacterium Alicyclobacillus acidoterrestris by semipreparative HPLC and by RP-HPLC with ESI is described. We used triple-quadrupole type mass spectrometer, 1H and 13C NMR for analyzing this complex lipid. CD spectra of two compounds (model compound—7-deoxy-d-glycero-d-allo-heptitol obtained by stereospecific synthesis, and an isolated derivative of hopane) were also measured and the absolute
configuration of both compounds was determined. On the basis of all the above methods, we identified the full structure of
a new class of bacteriohopanes, represented by various N-acylated bacteriohopanehexol-mannosamides. 相似文献
18.
Geelen Caspar V. C. Yntema Doekle R. Molenaar Jaap Keesman Karel J. 《Water Resources Management》2019,33(10):3339-3353
Water Resources Management - The increasing age and deterioration of drinking water mains is causing an increasing frequency of pipe bursts. Not only are pipe repairs costly, bursts might also lead... 相似文献
19.
Supercritical carbon dioxide (SC-CO2) extractions (with and without ethanol as an entrainer) were carried out to remove lipids and pigments from protein concentrate of green algae (Scenedesmus obliquus) cultivated under controlled conditions. The content and fatty acid composition of algal lipids using column, thin-layer (TLC) and gas-liquid chromatography (GLC) were determined. Absorption spectra of extracted fractions showed the predominance of chlorophyll A (lambda max at 410 nm). Single step supercritical carbon dioxide (SC-CO2) extraction resulted mostly in removal of neutral lipids and a part of glycolipids, but phospholipids were not extracted. Addition of ethanol to SC-CO2 increased the amount of glycolipids and phospholipids in the extract. TLC pattern of algal lipids showed that the main part of neutral lipids consisted of diglycerides, triglycerides, hydrocarbons, free sterols, and sterol esters. The glycolipids were mostly monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. In phospholipids, phosphatidyl choline, phosphatidyl glycerol, and phosphatidyl ethanolamine were the main compounds. Fatty acid composition patterns indicated the main fatty acids to be 16:0, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, and 18:3(a). Relatively high recovery of polyunsaturated fatty acids and essential fatty acids in supercritical fluid extracted algal lipids and proteins isolates were observed. 相似文献
20.
Zuzak KJ Naik SC Alexandrakis G Hawkins D Behbehani K Livingston EH 《Analytical chemistry》2007,79(12):4709-4715
We developed and characterized a new imaging platform for minimally invasive surgical venues, specifically a system to help guide laparoscopic surgeons to visualize biliary anatomy. This platform is a novel combination of a near-infrared hyperspectral imaging system coupled with a conventional surgical laparoscope. Intraoperative tissues are illuminated by optical fibers arranged in a ring around a center-mounted relay lens collecting back-reflected light from tissues to the hyperspectral imaging system. The system consists of a focal plane array (FPA) and a liquid crystal tunable filter, which is continuously tunable in the near-infrared spectral range of 650-1100 nm with the capability of passing light with a mean bandwidth of 6.95 nm, and the FPA is a high-sensitivity back-illuminated, deep depleted charge-coupled device. Placing a standard resolution target 5.1 cm from the distal end of the laparoscope, a typical intraoperative working distance, produced a 7.6-cm-diameter field of view with an optimal spatial resolution of 0.24 mm. In addition, the system's spatial and spectral resolution and its wavelength tuning accuracy are characterized. The spectroscopic images are formatted into a three-dimensional hyperspectral image cube and processed using principle component analysis. The processed images provide contrast based on measured spectra associated with chemically different anatomical structures helping identify the main molecular chromophores inherent to each tissue. The principal component images were found to image swine gallbladder and biliary structures from surrounding tissues, in real time, during cholecystectomy surgery. Furthermore, it is shown that surgeons can interrogate selected image subregions for their molecular composition identifying biliary anatomy during surgery and before any invasive action is undertaken. 相似文献