全文获取类型
收费全文 | 668篇 |
免费 | 35篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 1篇 |
综合类 | 2篇 |
化学工业 | 294篇 |
金属工艺 | 9篇 |
机械仪表 | 8篇 |
建筑科学 | 15篇 |
矿业工程 | 4篇 |
能源动力 | 25篇 |
轻工业 | 59篇 |
水利工程 | 6篇 |
石油天然气 | 13篇 |
无线电 | 24篇 |
一般工业技术 | 163篇 |
冶金工业 | 21篇 |
原子能技术 | 1篇 |
自动化技术 | 64篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 84篇 |
2021年 | 71篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 40篇 |
2015年 | 18篇 |
2014年 | 37篇 |
2013年 | 52篇 |
2012年 | 43篇 |
2011年 | 45篇 |
2010年 | 24篇 |
2009年 | 31篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 20篇 |
2005年 | 23篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有709条查询结果,搜索用时 15 毫秒
151.
Andrey Boroda Yuliya Privar Mariya Maiorova Irina Beleneva Marina Eliseikina Anna Skatova Dmitry Marinin Svetlana Bratskaya 《International journal of molecular sciences》2022,23(20)
The potential of chitosan and carboxymethyl chitosan (CMC) cryogels cross-linked with diglycidyl ether of 1,4-butandiol (BDDGE) and poly(ethylene glycol) (PEGDGE) have been compared in terms of 3D culturing HEK-293T cell line and preventing the bacterial colonization of the scaffolds. The first attempts to apply cryogels for the 3D co-culturing of bacteria and human cells have been undertaken toward the development of new models of host–pathogen interactions and bioimplant-associated infections. Using a combination of scanning electron microscopy, confocal laser scanning microscopy, and flow cytometry, we have demonstrated that CMC cryogels provided microenvironment stimulating cell–cell interactions and the growth of tightly packed multicellular spheroids, while cell–substrate interactions dominated in both chitosan cryogels, despite a significant difference in swelling capacities and Young’s modulus of BDDGE- and PEGDGE-cross-linked scaffolds. Chitosan cryogels demonstrated only mild antimicrobial properties against Pseudomonas fluorescence, and could not prevent the formation of Staphylococcus aureus biofilm in DMEM media. CMC cryogels were more efficient in preventing the adhesion and colonization of both P. fluorescence and S. aureus on the surface, demonstrating antifouling properties rather than the ability to kill bacteria. The application of CMC cryogels to 3D co-culture HEK-293T spheroids with P. fluorescence revealed a higher resistance of human cells to bacterial toxins than in the 2D co-culture. 相似文献
152.
Kristina A. Sharlo Irina D. Lvova Svetlana P. Belova Ksenia A. Zaripova Boris S. Shenkman Tatiana L. Nemirovskaya 《International journal of molecular sciences》2023,24(1)
Muscle unloading leads to signaling alterations that cause muscle atrophy and weakness. The cellular energy sensor AMPK can regulate myofiber-type shift, calcium-dependent signaling and ubiquitin-proteasome system markers. We hypothesized that the prevention of p-AMPK downregulation during the first week of muscle unloading would impede atrophy development and the slow-to-fast shift of soleus muscle fibers, and the aim of the study was to test this hypothesis. Thirty-two male Wistar rats were randomly assigned to four groups: placebo control (C), control rats treated with metformin (C + M), 7 days of hindlimb suspension (HS) + placebo (7HS), and 7 days of HS + metformin administration (7HS + M). In the soleus of the 7HS rats, we detected a slow-to-fast fiber-type shift as well as a significant downregulation of MEF-2D and p300 in the nuclei. In the 7HS group, we also found decreases in p-ACC (AMPK target) protein level and in the expression of E3 ubiquitin ligases and p-CaMK II protein level vs. the C group. The 7-day metformin treatment for soleus muscle unloading (1) prevented slow-to-fast fiber-type shift; (2) counteracted changes in the p-ACC protein level; (3) hindered changes in the nuclear protein level of the slow myosin expression activators MEF-2D and p300, but did not affect NFATc1 signaling; and (4) attenuated the unloading-induced upregulation of MuRF-1, atrogin-1, ubiquitin and myostatin mRNA expression, but did not prevent soleus muscle atrophy. Thus, metformin treatment during muscle disuse could be useful to prevent the decrease in the percentage of slow-type fatigue-resistant muscle fibers. 相似文献
153.
Chantal M. Wallenwein Verena Weigel Gtz Hofhaus Namrata Dhakal Wolfgang Schatton Svetlana Gelperina Florian K. Groeber-Becker Jennifer Dressman Matthias G. Wacker 《International journal of molecular sciences》2022,23(24)
Chronic wounds exhibit elevated levels of inflammatory cytokines, resulting in the release of proteolytic enzymes which delay wound-healing processes. In recent years, rifampicin has gained significant attention in the treatment of chronic wounds due to an interesting combination of antibacterial and anti-inflammatory effects. Unfortunately, rifampicin is sensitive to hydrolysis and oxidation. As a result, no topical drug product for wound-healing applications has been approved. To address this medical need two nanostructured hydrogel formulations of rifampicin were developed. The liposomal vesicles were embedded into hydroxypropyl methylcellulose (HPMC) gel or a combination of hyaluronic acid and marine collagen. To protect rifampicin from degradation in aqueous environments, a freeze-drying method was developed. Before freeze-drying, two well-defined hydrogel preparations were obtained. After freeze-drying, the visual appearance, chemical stability, residual moisture content, and redispersion time of both preparations were within acceptable limits. However, the morphological characterization revealed an increase in the vesicle size for collagen–hyaluronic acid hydrogel. This was confirmed by subsequent release studies. Interactions of marine collagen with phosphatidylcholine were held responsible for this effect. The HPMC hydrogel formulation remained stable over 6 months of storage. Moving forward, this product fulfills all criteria to be evaluated in preclinical and clinical studies. 相似文献
154.
Mangrove forests as a nature-based solution for coastal flood protection: Biophysical and ecological considerations 下载免费PDF全文
Rosanna van Hespen Zhan Hu Bas Borsje Michela De Dominicis Daniel A. Friess Svetlana Jevrejeva Maarten G. Kleinhans Maria Maza Celine E. J. van Bijsterveldt Tom Van der Stocken Bregje van Wesenbeeck Danghan Xie Tjeerd J. Bouma 《水科学与水工程》2023,16(1):1-13
Nature-based coastal protection is increasingly recognised as a potentially sustainable and cost-effective solution to reduce coastal flood risk. It uses coastal ecosystems such as mangrove forests to create resilient designs for coastal flood protection. However, to use mangroves effectively as a nature-based measure for flood risk reduction, we must understand the biophysical processes that govern risk reduction capacity through mangrove ecosystem size and structure. In this perspective, we evaluate the current state of knowledge on local physical drivers and ecological processes that determine mangrove functioning as part of a nature-based flood defence. We show that the forest properties that comprise coastal flood protection are well-known, but models cannot yet pinpoint how spatial heterogeneity of the forest structure affects the capacity for wave or surge attenuation. Overall, there is relatively good understanding of the ecological processes that drive forest structure and size, but there is a lack of knowledge on how daily bed-level dynamics link to long-term biogeomorphic forest dynamics, and on the role of combined stressors influencing forest retreat. Integrating simulation models of forest structure under changing physical (e.g. due to sea-level change) and ecological drivers with hydrodynamic attenuation models will allow for better projections of long-term natural coastal protection. 相似文献
155.
The ac conductivity of 70WO3–30P2O5 glass composition prepared by melt quenching was first studied in the temperature range 25°C to 350°C. The conductivity of the semiconducting glass is investigated with various electrodes (Pt and Ga‐Ag alloy). It is shown that the type of spectrum of cell impedance depends on the chosen electrodes. The influence of the samples geometry on the conduction is established. The influence of gas atmosphere (argon, oxygen, and air of different humidity) on electrical conductivity of tungsten‐phosphate glass on is studied for the first time. A mixed electronic‐ionic conductivity in the 70WO3–30P2O5 glass is found out. The transport numbers are shown as a function of temperature. Ionic and electronic contribution to the conduction is estimated. The electrical conductivity of glass undergoes changes from 8.6 × 10?8 (25°C) to 3.1 × 10?4 S/cm (300°C) in air. 相似文献
156.
Tamara B. Ivetić Yang Xia Omar Benzine Jelena Petrović Jelena Papan Svetlana R. Lukić-Petrović Alexander P. Litvinchuk 《Ceramics International》2021,47(4):4944-4953
Resultsof Electrochemical Impedance Spectroscopy (EIS) are reported for lithium-niobium-titanium-oxide (LNTO) ceramics synthesized by a solid-state reaction method with two functional additives (MoO3 or ZnO) in the temperature range 323 K - 573 K and frequencies between 10?1 Hz and 107 Hz. Scanning electron microscopy (SEM) reveals a textured morphology of rod and plate-like particles that are typical for M-phase LNTO materials, while X-ray diffraction (XRD) analysis confirms the formation of an M-phase member compound with an approximate structure of Li7Nb3Ti5O21. Complex impedance analysis indicates that its overall electrical resistivity behavior depends mostly on the grain boundary processes. EIS analysis shows a negative temperature coefficient of resistance behavior (NTCR) in a defined temperature range in two LNTOs and thermal activation of the conduction mechanisms. The low dielectric constants of 5.5 and 12.1 at 1 MHz were found for the first and second LNTOs, respectively. Complimentary Raman spectroscopic measurements, despite very large crystallographic unit cell of LNTO, reveal only a small number of lines, which is the consequence of a “molecular” nature of materials. 相似文献
157.
158.
Svetlana A. Kuznetsova Olga S. Khalipova Konstantin V. Lisitsa Alexander A. Ditts Alexandra G. Malchik Yu-Wen Chen Vladimir V. Kozik 《应用聚合物科学杂志》2021,138(34):50851
Anion exchange resins are widely used in template synthesis of oxide composites. The present work is aimed to study the thermal destruction of anion exchangers with divinyl-benzene and polyacrylate matrices in order to obtain hollow spherical MoO3/TiO2–SiO2 composites from these resins preliminarily saturated with paramolybate ion and coated with tetrabutoxytitanium sol with tetroethoxysilane. It is shown that the processes of resins decomposition affect the strength of spherical composites. Decomposition of the resin with a polyacrylate matrix, accompanied by random nucleation and burnout of the organic matrix at 350°C, leads to the formation of spherical oxide composites with cracks on the surface. The decomposition reactions of the resin with a divinylbenzene matrix occurring at the boundaries of the phases of cylindrical and spherical symmetry, as well as a lower burnout temperature of the organic matrix (290°C), contribute to the formation of dense MoO3/TiO2–SiO2 spheres. Hollow spherical composites 0.3–0.5 mm in size are orthorhombic α-MoO3 coated with a mixture of titanium dioxide with anatase structure and amorphous silicon dioxide. 相似文献
159.
Alexei Nikiforov-Nikishin Dimitri Nikiforov-Nikishin Nikita Kochetkov Svetlana Smorodinskaya Victor Klimov 《Microscopy research and technique》2022,85(2):538-547
This article presents results of the influence of three probiotic feed additive of various microbiological composition: Bacillus subtilis (VKPM B-2335); B. subtilis (OZ-2 VKPM-11966) + Bacillus amyloliquefaciens (OZ-3 VKPM-11967); Lactobacillus acidophilus (VKPM B-3235) on the growth and histology of the organs of the gastrointestinal tract of juvenile Oncorhynchus mykiss by morphometric parameters. These probiotic bacteria are the most commonly used in aquaculture. The effect of the probiotic feed additive led to the increase in fish growth and influenced different sections of the gastrointestinal tract. The biggest change was found in the mid intestine and the reliable difference compared with the control diet was obtained at the following parameters: lamina propria width, intraepithelial lymphocytes number of prismatic epithelium and goblet cells area. The changes in the pyloric appendages were less obvious but reported as playing an important functional role in digestion. The liver preserved normal functional structure in all series of the experiment except for the group with L. acidophilus, where hepatocyte small-drop vacuolization was observed. That might be connected with the change of the digest activity resulting from a decrease in secretory activity of the intestinal exocrinocytes. The use of all probiotic feed additives led to a similar change in morphometric parameters in all groups, which suggests a decrease in the immune response. 相似文献
160.
Ellya Bukharaeva Venera Khuzakhmetova Svetlana Dmitrieva Andrei Tsentsevitsky 《International journal of molecular sciences》2021,22(9)
Adrenoceptor activators and blockers are widely used clinically for the treatment of cardiovascular and pulmonary disorders. More recently, adrenergic agents have also been used to treat neurodegenerative diseases. Recent studies indicate a location of sympathetic varicosities in close proximity to neuromuscular junctions. The pressing question is whether there could be any effects of endo- or exogenous catecholamines on cholinergic neuromuscular transmission. It was shown that the pharmacological stimulation of adrenoceptors, as well as sympathectomy, can affect both acetylcholine release from motor nerve terminals and the functioning of postsynaptic acetylcholine receptors. In this review, we discuss the recent data regarding the effects of adrenergic drugs on neurotransmission at the neuromuscular junction. The elucidation of the molecular mechanisms by which the clinically relevant adrenomimetics and adrenoblockers regulate quantal acetylcholine release from the presynaptic nerve terminals and postsynaptic sensitivity may help in the design of highly effective and well-tolerated sympathomimetics for treating a number of neurodegenerative diseases accompanied by synaptic defects. 相似文献