全文获取类型
收费全文 | 1627篇 |
免费 | 80篇 |
专业分类
电工技术 | 15篇 |
综合类 | 1篇 |
化学工业 | 545篇 |
金属工艺 | 11篇 |
机械仪表 | 28篇 |
建筑科学 | 83篇 |
能源动力 | 77篇 |
轻工业 | 228篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 92篇 |
一般工业技术 | 245篇 |
冶金工业 | 117篇 |
原子能技术 | 12篇 |
自动化技术 | 246篇 |
出版年
2023年 | 22篇 |
2022年 | 100篇 |
2021年 | 107篇 |
2020年 | 44篇 |
2019年 | 41篇 |
2018年 | 53篇 |
2017年 | 44篇 |
2016年 | 69篇 |
2015年 | 57篇 |
2014年 | 69篇 |
2013年 | 120篇 |
2012年 | 84篇 |
2011年 | 106篇 |
2010年 | 92篇 |
2009年 | 85篇 |
2008年 | 65篇 |
2007年 | 72篇 |
2006年 | 52篇 |
2005年 | 53篇 |
2004年 | 46篇 |
2003年 | 39篇 |
2002年 | 23篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 17篇 |
1998年 | 47篇 |
1997年 | 32篇 |
1996年 | 29篇 |
1995年 | 12篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1707条查询结果,搜索用时 15 毫秒
81.
82.
Sintering behavior of Ba/Sr celsian precursor obtained from zeolite‐A by ion‐exchange method 下载免费PDF全文
Mattia Biesuz Luca Spiridigliozzi Antonello Marocco Gianfranco Dell'Agli Vincenzo M. Sglavo Michele Pansini 《Journal of the American Ceramic Society》2017,100(12):5433-5443
(Ba, Sr)‐exchanged zeolite A with composition Ba0.74Sr0.22Na0.04Al2Si2O8 was prepared by cation exchange; a mild thermal treatment converts into an amorphous phase. Successive crystallization and sintering behavior was studied by XRD, DTA, and thermodilatometric analysis. The results point out the activation of viscous flow sintering mechanisms between 900°C and 1050°C. The densification process starts when the amorphous phase reaches its glass transition temperature (897°C) and finishes when the material crystallizes forming hexacelsian. The application of an external pressure in such temperature range allows to achieve an almost complete densification, the material transforming at 1300°C into dense monoclinic celsian much below the typical processing temperature. 相似文献
83.
84.
85.
Anna Maria Laera Vincenzo Resta Emanuela Piscopiello Valerio Miceli Monica Schioppa Anna Grazia Scalone Francesca Di Benedetto Leander Tapfer 《Nanoscale research letters》2013,8(1):382
A straight synthetic route to fabricate hybrid nanocomposite films of well-dispersed CdS nanocrystals (NCs) in poly[2-methoxy-5-(2''-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) is reported. A soluble cadmium complex [Cd(SBz)2]2·MI, obtained by incorporating a Lewis base (1-methylimidazole, MI) on the cadmium bis(benzyl)thiol, is used as starting reagent in an in situ thermolytic process. CdS NCs with spherical shape nucleate and grow well below 200°C in a relatively short time (30 min). Photoluminescence spectroscopy measurements performed on CdS/MEH-PPV nanocomposites show that CdS photoluminescence peaks are totally quenched inside MEH-PPV, if compared to CdS/PMMA nanocomposites, as expected due to overlapping of the polymer absorption and CdS emission spectra. The CdS NCs are well-dispersed in size and homogeneously distributed within MEH-PPV matrix as proved by transmission electron microscopy. Nanocomposites with different precursor/polymer weight ratios were prepared in the range from 1:4 to 4:1. Highly dense materials, without NCs clustering, were obtained for a weight/weight ratio of 2:3 between precursor and polymer, making these nanocomposites particularly suitable for optoelectronic and solar energy conversion applications. 相似文献
86.
Gloria Rassu Vincenzo Zambrano Luigi Pinna Claudio Curti Lucia Battistini Andrea Sartori Giorgio Pelosi Franca Zanardi Giovanni Casiraghi 《Advanced Synthesis \u0026amp; Catalysis》2013,355(9):1881-1886
3‐Alkylidene‐2‐oxindoles represent a simple, yet enabling subfamily of indole alkaloids, and their ability to react as electron‐poor acceptors has largely been investigated. In contrast, their utility as pronucleophilic synthons remains elusive. In this context, the present article describes the successful execution of the direct, organocatalytic asymmetric Michael addition of prochiral 3‐alkylideneoxindoles to nitroolefins. A variety of γ‐substituted alkylideneoxindoles carrying two stereocenters at both the γ‐ and δ‐carbon sites was assembled with excellent stereoselectivity and without olefin isomerization or stereochemical ablation. 相似文献
87.
Federica Barbagallo Sandro La Vignera Rossella Cannarella Laura M. Mongioì Vincenzo Garofalo Claudia Leanza Marta Marino Aldo E. Calogero Rosita A. Condorelli 《International journal of molecular sciences》2022,23(2)
Obesity is a major current public health problem of global significance. A progressive sperm quality decline, and a decline in male fertility, have been reported in recent decades. Several studies have reported a strict relationship between obesity and male reproductive dysfunction. Among the many mechanisms by which obesity impairs male gonadal function, sirtuins (SIRTs) have an emerging role. SIRTs are highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that play a role in gene regulation, metabolism, aging, and cancer. SIRTs regulate the energy balance, the lipid balance, glucose metabolism, and adipogenesis, but current evidence also indicates a role for SIRTs in male reproduction. However, the majority of the studies have been conducted in animal models and very few have been conducted with humans. This review shows that SIRTs play an important role among the molecular mechanisms by which obesity interferes with male fertility. This highlights the need to deepen this relationship. It will be of particular interest to evaluate whether synthetic and/or natural compounds capable of modifying the activity of SIRTs may also be useful for the treatment of obesity and its effects on gonadal function. Although few studies have explored the role of SIRT activators in obesity-induced male infertility, some molecules, such as resveratrol, appear to be effective in modulating SIRT activity, as well as counteracting the negative effects of obesity on male fertility. The search for strategies to improve male reproductive function in overweight/obese patients is a challenge and understanding the role of SIRTs and their activators may open new interesting scenarios in the coming years. 相似文献
88.
Manana Kandashvili Georgi Gamkrelidze Lia Tsverava Tamar Lordkipanidze Eka Lepsveridze Vincenzo Lagani Maia Burjanadze Manana Dashniani Merab Kokaia Revaz Solomonia 《International journal of molecular sciences》2022,23(3)
Epilepsy is a severe neurological disease characterized by spontaneous recurrent seizures (SRS). A complex pathophysiological process referred to as epileptogenesis transforms a normal brain into an epileptic one. Prevention of epileptogenesis is a subject of intensive research. Currently, there are no clinically approved drugs that can act as preventive medication. Our previous studies have revealed highly promising antiepileptogenic properties of a compound–myo-inositol (MI) and the present research broadens previous results and demonstrates the long-term disease-modifying effect of this drug, as well as the amelioration of cognitive comorbidities. For the first time, we show that long-term treatment with MI: (i) decreases the frequency and duration of electrographic SRS in the hippocampus; (ii) has an ameliorating effect on spatial learning and memory deficit associated with epileptogenesis, and (iii) attenuates cell loss in the hippocampus. MI treatment also alters the expression of the glial fibrillary acidic protein, LRRC8A subunit of volume-regulated anion channels, and protein tyrosine phosphatase receptor type R, all expected to counteract the epileptogenesis. All these effects are still present even 4 weeks after MI treatment ceased. This suggests that MI may exert multiple actions on various epileptogenesis-associated changes in the brain and, therefore, could be considered as a candidate target for prevention of epileptogenesis. 相似文献
89.
90.
Lauralie Mangeot-Peter Sylvain Legay Jean-Francois Hausman Sergio Esposito Gea Guerriero 《International journal of molecular sciences》2016,17(9)
Gene expression profiling via quantitative real-time PCR is a robust technique widely used in the life sciences to compare gene expression patterns in, e.g., different tissues, growth conditions, or after specific treatments. In the field of plant science, real-time PCR is the gold standard to study the dynamics of gene expression and is used to validate the results generated with high throughput techniques, e.g., RNA-Seq. An accurate relative quantification of gene expression relies on the identification of appropriate reference genes, that need to be determined for each experimental set-up used and plant tissue studied. Here, we identify suitable reference genes for expression profiling in stems of textile hemp (Cannabis sativa L.), whose tissues (isolated bast fibres and core) are characterized by remarkable differences in cell wall composition. We additionally validate the reference genes by analysing the expression of putative candidates involved in the non-oxidative phase of the pentose phosphate pathway and in the first step of the shikimate pathway. The goal is to describe the possible regulation pattern of some genes involved in the provision of the precursors needed for lignin biosynthesis in the different hemp stem tissues. The results here shown are useful to design future studies focused on gene expression analyses in hemp. 相似文献