全文获取类型
收费全文 | 1195篇 |
免费 | 80篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 435篇 |
金属工艺 | 8篇 |
机械仪表 | 24篇 |
建筑科学 | 48篇 |
能源动力 | 29篇 |
轻工业 | 210篇 |
水利工程 | 7篇 |
石油天然气 | 12篇 |
无线电 | 48篇 |
一般工业技术 | 157篇 |
冶金工业 | 105篇 |
原子能技术 | 9篇 |
自动化技术 | 167篇 |
出版年
2023年 | 17篇 |
2022年 | 99篇 |
2021年 | 110篇 |
2020年 | 42篇 |
2019年 | 39篇 |
2018年 | 43篇 |
2017年 | 38篇 |
2016年 | 50篇 |
2015年 | 33篇 |
2014年 | 60篇 |
2013年 | 81篇 |
2012年 | 72篇 |
2011年 | 71篇 |
2010年 | 58篇 |
2009年 | 45篇 |
2008年 | 44篇 |
2007年 | 47篇 |
2006年 | 37篇 |
2005年 | 27篇 |
2004年 | 22篇 |
2003年 | 34篇 |
2002年 | 22篇 |
2001年 | 17篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 12篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1975年 | 7篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1961年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1277条查询结果,搜索用时 15 毫秒
991.
Caterina Franco Edoardo Sciatti Gaia Favero Francesca Bonomini Enrico Vizzardi Rita Rezzani 《International journal of molecular sciences》2022,23(22)
Among cardiovascular diseases, hypertension is one of the main risk factors predisposing to fatal complications. Oxidative stress and chronic inflammation have been identified as potentially responsible for the development of endothelial damage and vascular stiffness, two of the primum movens of hypertension and cardiovascular diseases. Based on these data, we conducted an open-label randomized study, first, to evaluate the endothelial damage and vascular stiffness in hypertense patients; second, to test the effect of supplementation with a physiological antioxidant (melatonin 1 mg/day for 1 year) in patients with essential hypertension vs. hypertensive controls. Twenty-three patients of either gender were enrolled and randomized 1:1 in two groups (control and supplemented group). The plasmatic total antioxidant capacity (as a marker of oxidative stress), blood pressure, arterial stiffness, and peripheral endothelial function were evaluated at the beginning of the study and after 1 year in both groups. Our results showed that arterial stiffness improved significantly (p = 0.022) in supplemented patients. The endothelial function increased too, even if not significantly (p = 0.688), after 1 year of melatonin administration. Moreover, the supplemented group showed a significative reduction in TAC levels (p = 0.041) correlated with the improvement of arterial stiffness. These data suggest that melatonin may play an important role in reducing the serum levels of TAC and, consequently, in improving arterial stiffness. 相似文献
992.
Alexandra Moreira-Pais Rita Nogueira-Ferreira Stephanie Reis Susana Aveiro Antnio Barros Tnia Melo Brbara Matos Jos Alberto Duarte Fernanda Seixas Pedro Domingues Francisco Amado Margarida Fardilha Paula A. Oliveira Rita Ferreira Rui Vitorino 《International journal of molecular sciences》2022,23(14)
Prostate cancer (PCa) is one of the most lethal diseases in men, which justifies the search for new diagnostic tools. The aim of the present study was to gain new insights into the progression of prostate carcinogenesis by analyzing the urine proteome. To this end, urine from healthy animals and animals with prostate adenocarcinoma was analyzed at two time points: 27 and 54 weeks. After 54 weeks, the incidence of pre-neoplastic and neoplastic lesions in the PCa animals was 100%. GeLC-MS/MS and subsequent bioinformatics analyses revealed several proteins involved in prostate carcinogenesis. Increased levels of retinol-binding protein 4 and decreased levels of cadherin-2 appear to be characteristic of early stages of the disease, whereas increased levels of enolase-1 and T-kininogen 2 and decreased levels of isocitrate dehydrogenase 2 describe more advanced stages. With increasing age, urinary levels of clusterin and corticosteroid-binding globulin increased and neprilysin levels decreased, all of which appear to play a role in prostate hyperplasia or carcinogenesis. The present exploratory analysis can be considered as a starting point for studies targeting specific human urine proteins for early detection of age-related maladaptive changes in the prostate that may lead to cancer. 相似文献
993.
Athir Boukhrissa Lina Mounia Rouidi Rita Maurício Hamid Ait-Amar 《Water and Environment Journal》2024,38(1):95-107
This study's purpose is to confirm the feasibility and performance of the combination between ‘electro-Fenton’ process and the ‘activated sludge’ biological process, in order to remove the organic matter contained in ‘intermediate’ leachates from technical landfill centre of Hamici (Algiers). This leachate was initially electrochemically pre-treated until the ratio of BOD5/chemical oxygen deman (COD) = 0.41, then an optimization of the parameters significantly influencing the biological degradation was carried. The results obtained after 13 h of biological treatment show the removal of 97% of the initial COD, with a mixed liquor composed of 700 mL of pre-treated leachate and 300 mL of activated sludge, a dissolved oxygen concentration of 3.5 mg O2/L and a pH of 7, which allows the effluent to discharge directly into the environment. The conclusions of this work are promising because it was demonstrated that if the operating parameters are well controlled concerning these treatments, its sequence and the referred pre-treatment, the treatment efficiency is very high to the point of direct discharge of the leachate. However, in future studies, the combination of the both processes should be more explored in order to reduce the treatment time and to scale-up the process. 相似文献
994.
A computative exploration is engraved on synchronized heat and mass transmission in a stream across a wedge. The problem has been executed for MHD incompressible viscous fluid, which annexes the impact of thermophoresis. The sequels of chemical reactions and energy sources have also been encountered. The resulting equations are transmuted as nondimensional forms and a numerical method is executed to solve the same. The numerical results for velocity, temperature, and concentration distributions are illustrated in the form of graphs for various dimensionless parameters affecting the problem. Numerical data are computed for skin friction coefficient, Nusselt number, and Sherwood number for different parameters. The results have been depicted for possible cases by means of pictorial visualizations. The present study has importance in various sectors of industrial and engineering applications. 相似文献
995.
Ottavia Bellotto Dr. Slavko Kralj Dr. Michele Melchionna Prof. Paolo Pengo Matic Kisovec Marjetka Podobnik Prof. Rita De Zorzi Prof. Silvia Marchesan 《Chembiochem : a European journal of chemical biology》2022,23(2):e202100518
Unprotected dipeptides are attractive building blocks for environmentally friendly hydrogel biomaterials by virtue of their low-cost and ease of preparation. This work investigates the self-assembling behaviour of the distinct stereoisomers of Ile-Phe and Phe-Ile in phosphate buffered saline (PBS) to form hydrogels, using transmission electron microscopy (TEM), attenuated total reflectance infrared spectroscopy (ATR-IR), circular dichroism (CD), and oscillatory rheometry. Each peptide purity and identity was also confirmed by 1H- and 13C-NMR spectroscopy and HPLC-MS. Finally, single-crystal XRD data allowed the key interactions responsible for the supramolecular packing into amphipathic layers or water-channels to be revealed. The presence of the latter in the crystal structure is a distinctive feature of the only gelator of this work that self-organizes into stable hydrogels, with fast kinetics and the highest elastic modulus amongst its structural isomers and stereoisomers. 相似文献
996.
Marco Savioli Manuela Stefanelli Gabriele Magna Francesca Zurlo Maria Federica Caso Rita Cimino Claudio Goletti Mariano Venanzi Corrado Di Natale Roberto Paolesse Donato Monti 《International journal of molecular sciences》2020,21(22)
Supramolecular chirality is one of the most important issues in different branches of science and technology, as stereoselective molecular recognition, catalysis, and sensors. In this paper, we report on the self-assembly of amphiphilic porphyrin derivatives possessing a chiral information on the periphery of the macrocycle (i.e., D- or L-proline moieties), in the presence of chiral amines as co-solute, such as chiral benzylamine derivatives. The aggregation process, steered by hydrophobic effect, has been studied in aqueous solvent mixtures by combined spectroscopic and topographic techniques. The results obtained pointed out a dramatic effect of these ligands on the morphology and on the supramolecular chirality of the final self-assembled structures. Scanning electron microscopy topography, as well as fluorescence microscopy studies revealed the formation of rod-like structures of micrometric size, different from the fractal structures formerly observed when the self-assembly process is carried out in the absence of chiral amine co-solutes. On the other hand, comparative experiments with an achiral porphyrin analogue strongly suggested that the presence of the prolinate moiety is mandatory for the achievement of the observed highly organized suprastructures. The results obtained would be of importance for unraveling the intimate mechanisms operating in the selection of the homochirality, and for the preparation of sensitive materials for the detection of chiral analytes, with tunable stereoselectivity and morphology. 相似文献
997.
Maria Pachetti Luisa Zupin Irene Venturin Elisa Mitri Rita Boscolo Francesco DAmico Lisa Vaccari Sergio Crovella Giuseppe Ricci Lorella Pascolo 《International journal of molecular sciences》2020,21(22)
Although being a crucial step for Assisted Reproduction Technologies (ART) success, to date sperm selection is based only on morphology, motility and concentration characteristics. Considering the many possible alterations, there is a great need for analytical approaches allowing more effective sperm selections. The use of Fourier Transform Infrared (FTIR) may represent an interesting possibility, being able to reveal many macromolecular changes in a single measurement in a nondestructive way. As a proof of concept, in this observational study, we used a FTIR approach to reveal features related to sperm quality and chemical changes promoted by in vitro capacitation. We found indication that α-helix content is increased in capacitated sperm, while high percentages of the β-structures seem to correlate to poor-quality spermatozoa. The most interesting observation was related to the lipid composition, when measured as CH2/CH3 vibrations (ratio 2853/2870), which resulted in being strongly influenced by capacitation and well correlated with sperm motility. Interestingly, this ratio is higher than 1 in infertile samples, suggesting that motility is related to sperm membranes stiffness and lipid composition. Although further analyses are requested, our results support the concept that FTIR can be proposed as a new smart diagnostic tool for semen quality assessment in ART. 相似文献
998.
999.
Amalfitano Domenico De Simone Vincenzo Scala Stefano Fasolino Anna Rita 《Software Quality Journal》2020,28(2):535-565
Software Quality Journal - Gap analysis is a common approach in industry to evaluate the gaps between the implemented software processes and the requirements of process quality frameworks or... 相似文献
1000.
Raf Van Campenhout Ana Rita Gomes Timo W.M. De Groof Serge Muyldermans Nick Devoogdt Mathieu Vinken 《International journal of molecular sciences》2021,22(7)
Gap junctions and connexin hemichannels mediate intercellular and extracellular communication, respectively. While gap junctions are seen as the “good guys” by controlling homeostasis, connexin hemichannels are considered as the “bad guys”, as their activation is associated with the onset and dissemination of disease. Open connexin hemichannels indeed mediate the transport of messengers between the cytosol and extracellular environment and, by doing so, fuel inflammation and cell death in a plethora of diseases. The present mini-review discusses the mechanisms involved in the activation of connexin hemichannels during pathology. 相似文献