全文获取类型
收费全文 | 1918篇 |
免费 | 106篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 38篇 |
综合类 | 1篇 |
化学工业 | 530篇 |
金属工艺 | 21篇 |
机械仪表 | 50篇 |
建筑科学 | 47篇 |
矿业工程 | 1篇 |
能源动力 | 44篇 |
轻工业 | 204篇 |
水利工程 | 17篇 |
石油天然气 | 6篇 |
无线电 | 149篇 |
一般工业技术 | 267篇 |
冶金工业 | 294篇 |
原子能技术 | 14篇 |
自动化技术 | 343篇 |
出版年
2024年 | 5篇 |
2023年 | 23篇 |
2022年 | 102篇 |
2021年 | 107篇 |
2020年 | 60篇 |
2019年 | 36篇 |
2018年 | 83篇 |
2017年 | 63篇 |
2016年 | 63篇 |
2015年 | 65篇 |
2014年 | 78篇 |
2013年 | 129篇 |
2012年 | 113篇 |
2011年 | 118篇 |
2010年 | 70篇 |
2009年 | 62篇 |
2008年 | 75篇 |
2007年 | 79篇 |
2006年 | 59篇 |
2005年 | 36篇 |
2004年 | 40篇 |
2003年 | 25篇 |
2002年 | 31篇 |
2001年 | 33篇 |
2000年 | 13篇 |
1999年 | 33篇 |
1998年 | 109篇 |
1997年 | 62篇 |
1996年 | 44篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 31篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1977年 | 16篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有2026条查询结果,搜索用时 0 毫秒
81.
Marialuisa Aragona Caterina Porcino Maria Cristina Guerrera Giuseppe Montalbano Rosaria Laur Marzio Cometa Maria Levanti Francesco Abbate Teresa Cobo Gabriel Capitelli Jos A. Vega Antonino German 《International journal of molecular sciences》2022,23(5)
The brain-derived neurotrophic factor (BDNF) was discovered in the last century, and identified as a member of the neurotrophin family. BDNF shares approximately 50% of its amino acid with other neurotrophins such as NGF, NT-3 and NT-4/5, and its linear amino acid sequences in zebrafish (Danio rerio) and human are 91% identical. BDNF functions can be mediated by two categories of receptors: p75NTR and Trk. Intriguingly, BDNF receptors were highly conserved in the process of evolution, as were the other NTs’ receptors. In this review, we update current knowledge about the distribution and functions of the BDNF-TrkB system in the sensory organs of zebrafish. In fish, particularly in zebrafish, the distribution and functions of BDNF and TrkB in the brain have been widely studied. Both components of the system, associated or segregated, are also present outside the central nervous system, especially in sensory organs including the inner ear, lateral line system, retina, taste buds and olfactory epithelium. 相似文献
82.
Maria Lisa Garavaglia Daniela Giustarini Graziano Colombo Francesco Reggiani Silvia Finazzi Marta Calatroni Lucia Landoni Nicola Marcello Portinaro Aldo Milzani Salvatore Badalamenti Ranieri Rossi Isabella Dalle-Donne 《International journal of molecular sciences》2022,23(5)
Thiols (sulfhydryl groups) are effective antioxidants that can preserve the correct structure of proteins, and can protect cells and tissues from damage induced by oxidative stress. Abnormal levels of thiols have been measured in the blood of patients with moderate-to-severe chronic kidney disease (CKD) compared to healthy subjects, as well as in end-stage renal disease (ESRD) patients on haemodialysis or peritoneal dialysis. The levels of protein thiols (a measure of the endogenous antioxidant capacity inversely related to protein oxidation) and S-thiolated proteins (mixed disulphides of protein thiols and low molecular mass thiols), and the protein thiolation index (the molar ratio of the S-thiolated proteins to free protein thiols in plasma) have been investigated in the plasma or red blood cells of CKD and ESRD patients as possible biomarkers of oxidative stress. This type of minimally invasive analysis provides valuable information on the redox status of the less-easily accessible tissues and organs, and of the whole organism. This review provides an overview of reversible modifications in protein thiols in the setting of CKD and renal replacement therapy. The evidence suggests that protein thiols, S-thiolated proteins, and the protein thiolation index are promising biomarkers of reversible oxidative stress that could be included in the routine monitoring of CKD and ESRD patients. 相似文献
83.
Salvatore Micali Gianmarco Isgro Giampaolo Bianchi Natalizia Miceli Gioacchino Calapai Michele Navarra 《Critical reviews in food science and nutrition》2014,54(8):1063-1075
Epidemiologic studies indicate that millions of people suffer from recurrent cystitis, a pathology requiring antibiotic prophylaxis and entailing high social costs. Cranberry is a traditional folk remedy for cystitis and, which, in the form of a variety of products and formulations has over several decades undergone extensive evaluation for the management of urinary tract infections (UTI). The aim of this retrospective study is to summarize and review the most relevant and recent preclinical and clinical studies on cranberries for the treatment of UTIs. The scientific literature selected for this review was identified by searches of Medline via PubMed. A variety of recent experimental evidence has shed light on the mechanism underlying the anti-adhesive properties of proanthrocyanidins, their structure–activity relationships, and pharmacokinetics. Analysis of clinical studies and evaluation of the cranberry efficacy/safety ratio in the prevention of UTIs strongly support the use of cranberry in the prophylaxis of recurrent UTIs in young and middle-aged women. However, evidence of its clinical use among other patients remains controversial. 相似文献
84.
85.
Salvatore Rionero 《Acta Mechanica》2013,224(2):447-458
The presence of more than one chemical dissolved in fluid mixtures is very often requested for describing natural phenomena (contaminant transport, underground water flow, acid rain effects, worming of the stratosphere). In the present paper, a triple convective-diffusive fluid mixture saturating a porous horizontal layer, heated from below and salted from above and below, is studied. In closed forms, conditions sufficient for (i) inhibiting the onset of convection and (ii) guaranteeing the global nonlinear stability of the thermal conduction solution and the absence of subcritical instabilities are obtained. 相似文献
86.
Salvatore Ventre Flavio Calvano Grégoire Pichenot Pierre Calmon Antonello Tamburrino 《NDT & E International》2011,44(4):376-386
This paper is focused on the Eddy Current Testing (ECT) method applied to important industrial applications such as the inspection of tubes in nuclear power plants and the inspection of planar surface from aeronautical industry. Specifically, we consider the prediction of the signatures produced by small defects through two fully three-dimensional numerical models developed for ECT. In particular we consider the responses to small defects described in two experimental benchmarks from nuclear power industry and one experimental benchmark from aeronautical applications. Despite of the small size of the defects that, in some cases, is of the order of few millimetres, the numerical models reproduce correctly the experimental responses provided in the benchmarks, including the challenging case of a defect (in a tube) close to the support plate. 相似文献
87.
Antonino Rizzuti Rocco Caliandro Vito Gallo Piero Mastrorilli Giuseppe Chita Mario Latronico 《Food chemistry》2013
X-ray powder diffraction was combined, for the first time, with Nuclear Magnetic Resonance spectroscopy and direct infusion mass spectrometry to characterise fresh and brined grape leaves. Covariance analysis of data generated by the three techniques was performed with the aim to correlate information deriving from the solid part with those obtained for soluble metabolites. The results obtained indicate that crystalline components can be correlated to the metabolites contained in the grape leaves, paving the way to the use of X-ray diffraction analysis for food fingerprinting purposes. Moreover it was ascertained that, differently from most of the metabolites present in the fresh vine leaves, linolenic acid (an omega-3-fatty acid) and quercetin-3-O-glucuronide (a polyphenol metabolite) do not undergo sensible degradation during the brining process, which is used as preservative method for the grape leaves. 相似文献
88.
Davide Bilò Hans-Joachim Böckenhauer Dennis Komm Richard Královič Tobias Mömke Sebastian Seibert Anna Zych 《Algorithmica》2011,61(2):227-251
A reoptimization problem describes the following scenario: given an instance of an optimization problem together with an optimal
solution for it, we want to find a good solution for a locally modified instance. 相似文献
89.
The paper is the introduction to the special issue Water Engineering and Management in a Changing Environment which presents a set of the most innovative contributions at the EWRA Symposium, held in Catania, Italy on 2011. 相似文献
90.
Massimiliano Tomasulo Erhan Deniz Tiziana Benelli Salvatore Sortino Françisco M. Raymo 《Advanced functional materials》2009,19(24):3956-3961
Two macromolecular constructs incorporating a single polymer backbone with multiple photochromic side chains are developed. Both systems are prepared from preformed photochromic [1,3]oxazines after the ring‐opening polymerization of their norbornene appendages. In solution, UV illumination of these polymers opens the [1,3]oxazine rings in their side chains in less than 6 ns and with a quantum yield of 0.09 in both instances. The photogenerated species incorporate a 4‐nitrophenolate chromophore, and hence, their formation is accompanied by the appearance of an intense band in the visible region of the absorption spectrum. The photoproducts revert spontaneously to the original state with first‐order kinetics in microseconds. Furthermore, both photochromic polymers tolerate hundreds of switching cycles with no sign of degradation, even in the presence of molecular oxygen. Thus, this design logic and choice of functional building blocks can translate into the realization of innovative photoresponsive materials with excellent photochromic performance. 相似文献