全文获取类型
收费全文 | 1557篇 |
免费 | 46篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 25篇 |
综合类 | 3篇 |
化学工业 | 289篇 |
金属工艺 | 32篇 |
机械仪表 | 51篇 |
建筑科学 | 34篇 |
矿业工程 | 4篇 |
能源动力 | 211篇 |
轻工业 | 137篇 |
水利工程 | 11篇 |
石油天然气 | 11篇 |
无线电 | 193篇 |
一般工业技术 | 344篇 |
冶金工业 | 64篇 |
原子能技术 | 7篇 |
自动化技术 | 193篇 |
出版年
2024年 | 6篇 |
2023年 | 31篇 |
2022年 | 82篇 |
2021年 | 73篇 |
2020年 | 58篇 |
2019年 | 39篇 |
2018年 | 69篇 |
2017年 | 51篇 |
2016年 | 50篇 |
2015年 | 34篇 |
2014年 | 47篇 |
2013年 | 144篇 |
2012年 | 79篇 |
2011年 | 90篇 |
2010年 | 64篇 |
2009年 | 89篇 |
2008年 | 66篇 |
2007年 | 53篇 |
2006年 | 38篇 |
2005年 | 29篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 18篇 |
1994年 | 14篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 4篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
排序方式: 共有1609条查询结果,搜索用时 15 毫秒
91.
Elena Ermolenko Anna Simanenkova Lyubov Voropaeva Nadezhda Lavrenova Maryna Kotyleva Sarkis Minasian Alena Chernikova Natalya Timkina Nikita Gladyshev Alexander Dmitriev Alexander Suvorov Michael Galagudza Tatiana Karonova 《International journal of molecular sciences》2022,23(12)
Metformin is a first-line drug for DM2 treatment and prevention, but its complex effect on impaired glucose tolerance (IGT), including its influence on myocardial resistance to ischemia-reperfusion injury, is not completely studied. We aimed to evaluate the influence of metformin on the intestinal microbiota (IM), metabolism, and functional and morphological characteristics of myocardium in rats with IGT. IGT was modelled in SPF Wistar rats with a high-fat diet and streptozotocin and nicotinamide injection. Rats were divided into three groups: IGT (without treatment), IGT MET (metformin therapy), and CRL (without IGT induction and treatment). IGT group was characterized by: higher body weight, increased serum glucose and total cholesterol levels, atherogenic coefficient, impairment in the functional parameters of the isolated heart during perfusion, and larger myocardium infarction (MI) size in comparison with the CRL group. IM of IGT rats differed from that of CRL: an increase of Bacteroides, Acinetobacter, Akkermansia, Roseburia, and a decrease of Lactobacillus genera representation. Metformin therapy led to the diminishing of metabolic syndrome (MS) symptoms, which correlated with IM restoration, especially with the growth of Akkermansia spp. and decline of Roseburia populations and their influence on other members of IM. The obtained results allow us to consider from a new point of view the expediency of probiotic A. muciniphila use for MS treatment. 相似文献
92.
Arturo B. Soro Paul Whyte Declan J. Bolton Brijesh K. Tiwari 《Comprehensive Reviews in Food Science and Food Safety》2020,19(4):1353-1377
Campylobacteriosis is one of the most common bacterial infections worldwide causing economic costs. The high prevalence of Campylobacter spp. in poultry meat is a result of several contamination and cross‐contamination sources through the production chain. Moreover, survival mechanisms, such as biofilm formation, viable but nonculturable state, and antimicrobial resistance, enable its persistence during food processing. Therefore, mitigation strategies are necessary in order to avoid and/or inactivate Campylobacter at farm, abattoir, industry, and retail level. In this review, a number of potential strategies and novel technologies that could reduce the prevalence of Campylobacter in poultry meat have been identified and evaluated to provide a useful overview. At farm level for instance, biosecurity, bacteriocins, probiotics, feed and water additives, bacteriophages, and vaccination could potentially reduce colonization in chicken flocks. However, current technologies used in the chicken slaughter and processing industry may be less effective against this foodborne pathogen. Novel technologies and strategies such as cold plasma, ultraviolet light, high‐intensity light pulses, pulsed electric fields, antimicrobials, and modified atmosphere packaging are discussed in this review for reducing Campylobacter contamination. Although these measures have achieved promising results, most have not been integrated within processing operations due to a lack of knowledge or an unwillingness to implement these into existing processing systems. Furthermore, a combination of existing and novel strategies might be required to decrease the prevalence of this pathogen in poultry meat and enhance food safety. Therefore, further research will be essential to assess the effectiveness of all these strategies. 相似文献
93.
Mantri M Loik ND Hamed RB Claridge TD McCullagh JS Schofield CJ 《Chembiochem : a European journal of chemical biology》2011,12(4):531-534
Amino acid analyses reveal that JMJD6-catalysed hydroxylation of RNA-splicing regulatory protein fragments occurs to give hydroxylysine products with 5S stereochemistry. This contrasts with collagen lysyl hydroxylases, which give 5R-hydroxylated products. The work suggests that more than one subfamily of lysyl hydroxylases has evolved and illustrates the importance of stereochemical assignments in proteomic analyses. 相似文献
94.
Anamika Sharma Vikrant Nain Rameshwar Tiwari Surender Singh 《Chemical Engineering Communications》2018,205(3):402-410
Microbial production of ethanol and 2,3-butanediol (2,3-BD) from agro-residues has been attracting interest because of their applications in various industries, including generation of biofuel molecules. In the present investigation, the hemicellulosic fraction of corncob was hydrolyzed by indigenous holocellulase from novel psychrotolerant Aspergillus niger SH3 resulting in high xylose release (34.61?g?L?1), followed by the bioconversion of xylose to ethanol and 2,3-BD. Taguchi design was adopted to optimize the process which resulted in 5.25- and 3.31-fold increase in 2,3-BD (12.18?±?0.53?g?L?1) and ethanol (4.08?±?0.03?g?L?1), as compared with un-optimized condition. For the first time, co-production of ethanol and 2,3-BD from the corncob hemicellulosic hydrolysate was performed using a newly isolated Klebsiella oxytoca XF7 strain, under the optimized fermentation conditions. These results suggest that K. oxytoca XF7 is a promising candidate for co-production of ethanol and 2,3-BD, with high xylose conversion efficiency (96.65%), facilitating the economical production of biofuel molecules. 相似文献
95.
Ram Gopal Ankit Goyal Ajay Saini Meena Nagar Nikita Sharma Deepak Kumar Gupta Veena Dhayal 《Ceramics International》2018,44(16):19099-19105
Synthesis of mono-crystalline Ga2O3 Nanorods was done by sol-gel transformation of gallium(III) isopropoxide (Ga(OPri)3). XRD studies were done to determine the planes and crystal structure of synthesized nanorods that showed the synthesis of β-Ga2O3(a). TEM studies of synthesized Ga2O3 confirmed the synthesis of monocrystalline β-Ga2O3 nanorods. To study the effect of precursor chemistry and to determine role of precursor structures on the crystal structure, phase and morphology of the Ga2O3, a new modified precursor complex was synthesized. The reaction of Ga(OPri)3 with N-phenylsalicylaldimine, [C6H4(OH)CH=N(C6H5)] in 1:1?M ratio yielded [{(H5C6)N?=?CH-C6H4O}Ga(OPri)2]. The newly synthesized complex was characterized by elemental analyses, molecular weight measurement, FT-IR and NMR (1H and 13C) spectral studies. Spectral studies of the modified complex suggest the presence of bi-dentate mode of attachment of Schiff's base in the solution state. Sol-gel transformations of [{(H5C6)N?=?CH-C6H4O}Ga(OPri)2] in organic medium, yielded γ-Ga2O3(b), as found by XRD studies. TEM image of the sample (a) revealed the formation of nano-rods of oxide with average diameter of ~100?nm whereas the TEM image of sample (b) showed presence of nano-sized particles of oxide with average particle size of 10?nm. Morphological and compositional studies of synthesized samples (a) and (b) were carried out using SEM and EDX. The method provides a possibility of large scale synthesis of dissimilar shaped and pure Ga2O3 nanoparticles. 相似文献
96.
An indoor simulation study was carried out to evaluate heat and mass transfer relation for a semi-cylindrical metallic (opaque) condensing cover for higher yields at different operating temperatures under free and forced modes of operation. The objective is to design a distillation unit for higher yield for commercialization, particularly in India. Experiments have been conducted for the operating temperature range of 40°C to 80°C in a steady-state condition by using constant temperature bath. Data (temperature and yield) obtained from experimentation have been used to determine the values of coefficient C and n and, consequently, convective as well as evaporative heat transfer coefficients. It is inferred that a higher yield is obtained with an increase of temperature in the forced mode of operation as compared to that in the natural mode of operation due to a fast release of heat from the condensing cover. 相似文献
97.
Rajender Prasad Tiwari Syed Zimad Husain Hashmi Raghav Sharma Saif Ahmad Khan Balaji Birajdar 《Journal of the American Ceramic Society》2019,102(8):4659-4669
Residual NiO phase is generally detected in 0.9(KNbO3)–0.1(BaNi1/2Nb1/2O3-δ) (KBNNO) synthesized using NiO as a nickel precursor by solid-state reaction. In this work, NiO phase is found to exist in the form of the residual NiO particles with a size of 100-200 nm using energy dispersive X-ray elemental mapping. These NiO residual particles are eliminated by using nickel acetate as a nickel precursor and a 100% perovskite phase KBNNO is successfully synthesized at as low as 600°C temperature. Furthermore, using the two-step sintering technique, 100% relative density is achieved in this material. The nickel acetate–based KBNNO shows a robust ferromagnetism with the saturation magnetization of 11.42 memu/g and the remanent magnetization of 3.89 memu/g which is 38 times higher than that of previously reported value in NiO-based KBNNO. Thus, a highly pure and fully dense KBNNO ceramic with superior magnetic properties is obtained using nickel acetate and by the two-step sintering method. This is a key step forward in the processing of KBNNO and is likely to have a significant impact on other physical properties of this newly invented and promising photovoltaic perovskite material. 相似文献
98.
Dina Yu. Stolyarova Nikita M. Kuznetsov Sergey I. Belousov Sergei N. Chvalun 《应用聚合物科学杂志》2019,136(25):47678
The electrorheological (ER) behavior of modified montmorillonite (MMT) suspensions in polydimethylsiloxane is studied. As established by rotational viscometry, the samples with a dispersed phase concentration from 1 to 8 wt % reveal viscous Newtonian behavior and dramatically change their properties to elastic when electric field is applied. The rheological characteristics of the suspensions over 0–7 kV mm−1 range of electric field strengths are also studied. Novel X-ray diffraction method is developed to evaluate the suspension of the filler in a siloxane medium and to calculate the degree of its exfoliation. The dependence of exfoliation degree, dielectric, and ER characteristics on the type of modifier in the MMT structure is considered. Based on the obtained data, a new model of system behavior with the various types of fillers is proposed and the prospects of utilizing MMT as a filler for ER fluids are demonstrated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47678. 相似文献
99.
A. V. Raut R. K. Satvekar S. S. Rohiwal A. P. Tiwari A. Gnanamani S. Pushpavanam 《Designed Monomers and Polymers》2016,19(5):445-455
This study for the first time shows the effective utilization and production of chitin monomers at laboratory level, with immense potential for its biomedical application. Low molecular weight (LMW) N-acetylglucosamine (GlcNAc) is prepared by depolymerization of chitin using chemical method coupled with a physical separation method. A novel filtration strategy exploiting polysulfone hollow fiber membrane is used for the preparation of GlcNAc particles with 94% yield within 8.5 ± 0.5 h. This high efficiency is analyzed using high-pressure liquid chromatography. The GlcNAc obtained was further analyzed using dynamic light scattering, first derivative Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The antimicrobial properties of GlcNAc, chitin, and GlcNAc/chitin mixture were investigated using minimal inhibitory concentration against S. aureus and E. coli. Bacteriostatic property was exhibited by high molecular weight chitin, while GlcNAc and GlcNAc/chitin mixture (LMW) demonstrated bactericidal activity. Blood biocompatibility below 0.25 g/ml and cytocompatibility with NIH3T3 fibroblast cells and the proliferative efficacy suggested its utilization and suitability of these particles in biological applications. 相似文献
100.
Singh Rajeev Kumar Tiwari Akhilesh Gupta Rajendra Kumar 《Multimedia Tools and Applications》2022,81(5):6051-6067
Multimedia Tools and Applications - Currently, Deep Learning is playing an influential role for Image analysis and object classification. Maize’s diseases reduce production that subsequently... 相似文献