全文获取类型
收费全文 | 4062篇 |
免费 | 188篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 21篇 |
综合类 | 8篇 |
化学工业 | 902篇 |
金属工艺 | 44篇 |
机械仪表 | 45篇 |
建筑科学 | 185篇 |
矿业工程 | 13篇 |
能源动力 | 67篇 |
轻工业 | 711篇 |
水利工程 | 26篇 |
石油天然气 | 9篇 |
无线电 | 119篇 |
一般工业技术 | 481篇 |
冶金工业 | 1086篇 |
原子能技术 | 24篇 |
自动化技术 | 513篇 |
出版年
2023年 | 20篇 |
2021年 | 138篇 |
2020年 | 82篇 |
2019年 | 98篇 |
2018年 | 108篇 |
2017年 | 84篇 |
2016年 | 100篇 |
2015年 | 94篇 |
2014年 | 135篇 |
2013年 | 260篇 |
2012年 | 174篇 |
2011年 | 227篇 |
2010年 | 190篇 |
2009年 | 154篇 |
2008年 | 210篇 |
2007年 | 189篇 |
2006年 | 145篇 |
2005年 | 133篇 |
2004年 | 117篇 |
2003年 | 95篇 |
2002年 | 119篇 |
2001年 | 68篇 |
2000年 | 60篇 |
1999年 | 80篇 |
1998年 | 73篇 |
1997年 | 43篇 |
1996年 | 66篇 |
1995年 | 47篇 |
1994年 | 54篇 |
1993年 | 53篇 |
1992年 | 61篇 |
1990年 | 49篇 |
1989年 | 68篇 |
1988年 | 42篇 |
1987年 | 50篇 |
1986年 | 55篇 |
1985年 | 53篇 |
1984年 | 55篇 |
1983年 | 43篇 |
1982年 | 30篇 |
1981年 | 46篇 |
1980年 | 26篇 |
1979年 | 23篇 |
1978年 | 22篇 |
1977年 | 21篇 |
1976年 | 30篇 |
1975年 | 26篇 |
1974年 | 15篇 |
1973年 | 16篇 |
1970年 | 18篇 |
排序方式: 共有4254条查询结果,搜索用时 31 毫秒
1.
Krzysztof M. Tokarz Wojciech Wesoowski Barbara Tokarz Wojciech Makowski Anna Wysocka Roman J. Jdrzejczyk Karolina Chrabaszcz Kamilla Malek Anna Kostecka-Gugaa 《International journal of molecular sciences》2021,22(2)
Grass pea (Lathyrus sativus) is a leguminous plant of outstanding tolerance to abiotic stress. The aim of the presented study was to describe the mechanism of grass pea (Lathyrus sativus L.) photosynthetic apparatus acclimatisation strategies to salinity stress. The seedlings were cultivated in a hydroponic system in media containing various concentrations of NaCl (0, 50, and 100 mM), imitating none, moderate, and severe salinity, respectively, for three weeks. In order to characterise the function and structure of the photosynthetic apparatus, Chl a fluorescence, gas exchange measurements, proteome analysis, and Fourier-transform infrared spectroscopy (FT-IR) analysis were done inter alia. Significant differences in the response of the leaf and stem photosynthetic apparatus to severe salt stress were observed. Leaves became the place of harmful ion (Na+) accumulation, and the efficiency of their carboxylation decreased sharply. In turn, in stems, the reconstruction of the photosynthetic apparatus (antenna and photosystem complexes) activated alternative electron transport pathways, leading to effective ATP synthesis, which is required for the efficient translocation of Na+ to leaves. These changes enabled efficient stem carboxylation and made them the main source of assimilates. The observed changes indicate the high plasticity of grass pea photosynthetic apparatus, providing an effective mechanism of tolerance to salinity stress. 相似文献
2.
Speciation of copper in high chloride concentrations,in the context of corrosion of copper canisters
Canisters with a cast iron insert for mechanical strength and a 50-mm thick copper shell as corrosion protection are planned to be used for disposal of spent nuclear fuel in Sweden and Finland. Chloride can be considered “beneficial”, as it promotes active dissolution of copper rather than passivation (which might result in pitting), but a high concentration of chloride in solution would increase the driving force for corrosion through the formation of soluble copper chloro complexes. Thermodynamic calculations are performed in this study with the PHREEQC software and three of its accompanying databases, and a comparison with experimental data is performed to select the database to be used when evaluating repository performance. The activity coefficient models are given special attention. For the assessment of chloride-assisted corrosion of a KBS-3 canister, chloride concentrations pessimistically up to 5 mol/kg are used (in Finland and Sweden, the groundwater and bentonite porewater chloride concentrations are not expected to exceed 1 mol/kg). The resulting copper solubilities are then considered in different mass transport cases. 相似文献
3.
Barbara Malinowska Marta Baranowska-Kuczko Aleksandra Kicman Eberhard Schlicker 《International journal of molecular sciences》2021,22(4)
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may lead to coronavirus disease 2019 (COVID-19) which, in turn, may be associated with multiple organ dysfunction. In this review, we present advantages and disadvantages of cannabidiol (CBD), a non-intoxicating phytocannabinoid from the cannabis plant, as a potential agent for the treatment of COVID-19. CBD has been shown to downregulate proteins responsible for viral entry and to inhibit SARS-CoV-2 replication. Preclinical studies have demonstrated its effectiveness against diseases of the respiratory system as well as its cardioprotective, nephroprotective, hepatoprotective, neuroprotective and anti-convulsant properties, that is, effects that may be beneficial for COVID-19. Only the latter two properties have been demonstrated in clinical studies, which also revealed anxiolytic and antinociceptive effects of CBD (given alone or together with Δ9-tetrahydrocannabinol), which may be important for an adjuvant treatment to improve the quality of life in patients with COVID-19 and to limit post-traumatic stress symptoms. However, one should be aware of side effects of CBD (which are rarely serious), drug interactions (also extending to drugs acting against COVID-19) and the proper route of its administration (vaping may be dangerous). Clearly, further clinical studies are necessary to prove the suitability of CBD for the treatment of COVID-19. 相似文献
4.
Marta Baranowska-Kuczko Hanna Kozowska Monika Kloza Ewa Harasim-Symbor Micha Biernacki Irena Kasacka Barbara Malinowska 《International journal of molecular sciences》2021,22(9)
Our study aimed to examine the effects of hypertension and the chronic administration of the fatty acid amide hydrolase (FAAH) inhibitor URB597 on vascular function and the endocannabinoid system in spontaneously hypertensive rats (SHR). Functional studies were performed on small mesenteric G3 arteries (sMA) and aortas isolated from SHR and normotensive Wistar Kyoto rats (WKY) treated with URB597 (1 mg/kg; twice daily for 14 days). In the aortas and sMA of SHR, endocannabinoid levels and cannabinoid CB1 receptor (CB1R) expression were elevated. The CB1R antagonist AM251 diminished the methanandamide-evoked relaxation only in the sMA of SHR and enhanced the vasoconstriction induced by phenylephrine and the thromboxane analog U46619 in sMA in SHR and WKY. In the sMA of SHR, URB597 elevated anandamide levels, improved the endothelium-dependent vasorelaxation to acetylcholine, and in the presence of AM251 reduced the vasoconstriction to phenylephrine and enhanced the vasodilatation to methanandamide, and tended to reduce hypertrophy. In the aortas, URB597 elevated endocannabinoid levels improved the endothelium-dependent vasorelaxation to acetylcholine and decreased CB1R expression. Our study showed that hypertension and chronic administration of URB597 caused local, resistance artery-specific beneficial alterations in the vascular endocannabinoid system, which may bring further advantages for therapeutic application of pharmacological inhibition of FAAH. 相似文献
5.
6.
Dr. Barbara Wienen-Schmidt Matthias Oebbeke Dr. Khang Ngo Prof. Dr. Andreas Heine Prof. Dr. Gerhard Klebe 《ChemMedChem》2021,16(1):292-300
In lead optimization, protein crystallography is an indispensable tool to analyze drug binding. Binding modes and non-covalent interaction inventories are essential to design follow-up synthesis candidates. Two protocols are commonly applied to produce protein–ligand complexes: cocrystallization and soaking. Because of its time and cost effectiveness, soaking is the more popular method. Taking eight ligand hinge binders of protein kinase A, we demonstrate that cocrystallization is superior. Particularly for flexible proteins, such as kinases, and larger ligands cocrystallization captures more reliable the correct binding pose and induced protein adaptations. The geometrical discrepancies between soaking and cocrystallization appear smaller for fragment-sized ligands. For larger flexible ligands that trigger conformational changes of the protein, soaking can be misleading and underestimates the number of possible polar interactions due to inadequate, highly impaired positions of protein amino-acid side and main chain atoms. Thus, if applicable cocrystallization should be the gold standard to study protein–ligand complexes. 相似文献
7.
Dr. Daniela Carbone Dr. Barbara Parrino Dr. Stella Cascioferro Camilla Pecoraro Prof. Elisa Giovannetti Dr. Veronica Di Sarno Dr. Simona Musella Dr. Giulia Auriemma Prof. Girolamo Cirrincione Prof. Patrizia Diana 《ChemMedChem》2021,16(3):537-554
A new series of topsentin analogs, in which the central imidazole ring of the natural lead was replaced by a 1,2,4-oxadiazole moiety, was efficiently synthesized. All derivatives were pre-screened for antiproliferative activity against the National Cancer Institute (NCI-60) cell lines panel. The five most potent compounds were further investigated in various pancreatic ductal adenocarcinoma (PDAC) cell lines, including SUIT-2, Capan-1, and Panc-1 cells, eliciting EC50 values in the micromolar and sub-micromolar range, associated with significant reduction of cell migration. These remarkable results might be explained by the effects of these new topsentin analogues on epithelial-to-mesenchymal transition markers, including SNAIL-1/2 and metalloproteinase-9. Moreover, flow cytometric analysis after Annexin V-FITC and propidium iodide staining demonstrated that these derivatives enhanced apoptosis of PDAC cells. Keeping with these data, the PathScan intracellular signaling and ELISA array revealed cleavage of caspase-3 and PARP and a significant inhibition of GSK3β phosphorylation, suggesting this kinase as a potential downstream target of our novel compounds. This was further supported by a specific assay for the evaluation of GSK3β activity, showing IC50 values for the most active compounds against this enzyme in the micromolar range. 相似文献
8.
The Different Physical and Chemical Composition of Grape Juice and Marc Influence Saccharomyces cerevisiae Strains Distribution During Fermentation 下载免费PDF全文
9.
Nonthermal Technologies for Fruit and Vegetable Juices and Beverages: Overview and Advances 下载免费PDF全文
Antonio Bevilacqua Leonardo Petruzzi Marianne Perricone Barbara Speranza Daniela Campaniello Milena Sinigaglia Maria Rosaria Corbo 《Comprehensive Reviews in Food Science and Food Safety》2018,17(1):2-62
In recent years, there has been a growing interest in the design of novel nonthermal processing systems that minimally modify sensory, nutritional, and functional properties of fruit and vegetable juices and beverages. The benefits of nonthermal treatments are strongly dependent on the food matrix. Thus, an understanding of the effects that these technologies exert on the properties of juices and beverages is important to design and optimize technological parameters to produce value‐added products. This review covers research on nonthermal electrical treatments, high pressure processing, ultrasound, radiation processing, inert gas treatments, cold plasma, and membrane processing. Advances towards optimization of processing conditions, and combined technologies approaches have been also extensively reviewed. This information could be useful to: (1) manage processing systems and optimize resources; (2) preserve nutritional value and organoleptic properties, and (3) provide processing conditions for validation of these technologies at the industrial scale. 相似文献
10.
Bartłomiej Grygorcewicz Wioleta Chajęcka-Wierzchowska Adrian Augustyniak Agata Wasak Xymena Stachurska Paweł Nawrotek Barbara Dołęgowska 《Journal of Food Safety》2020,40(2):e12747
Shiga toxin-producing Escherichia coli is a common foodborne pathogen which transmission includes dairy products. In the search for novel biocontrol methods, bacteriophages have become important candidates for the eradication of foodborne pathogens. The aim of this study was to evaluate the bacteriophage-mediated reduction of E. coli O157:H7 in raw and filtered milk. Laboratory-scale tests showed that the bacteriophage ECPS-6 efficiently adsorbed to E. coli O157: H7 cells. Furthermore, ECPS-6 remained stable when heated at 70°C for 20 min and in a wide pH range from 3.0 to 11.0. The trials on contaminated milk were performed using filtered and unfiltered raw milk contaminated with 1 × 105 CFU × ml−1 of E. coli O157: H7. Bacteriophage was added at multiplicity of infection (MOI) 5 and 50. The ECPS-6 reached the highest lytic activity at MOI = 5 (25°C) which resulted in 4.74 Log10 CFU × ml−1 and 7.3 Log10 CFU × ml−1 reduction after 10 days for both tested strains, respectively. Under refrigerated conditions (4°C) the quantity of E. coli decreased to 1.5 Log10 CFU × ml−1 and 3.04 Log10 CFU × ml−1 for these strains, respectively. Usage of MOI = 50 for the treatment unfiltered milk led to the reduction of E. coli O157:H7 A-2 below the detection limit after 6 hr. 相似文献