全文获取类型
收费全文 | 3263篇 |
免费 | 189篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 35篇 |
综合类 | 10篇 |
化学工业 | 1094篇 |
金属工艺 | 58篇 |
机械仪表 | 60篇 |
建筑科学 | 57篇 |
矿业工程 | 12篇 |
能源动力 | 146篇 |
轻工业 | 165篇 |
水利工程 | 17篇 |
石油天然气 | 12篇 |
武器工业 | 1篇 |
无线电 | 311篇 |
一般工业技术 | 818篇 |
冶金工业 | 142篇 |
原子能技术 | 51篇 |
自动化技术 | 478篇 |
出版年
2023年 | 51篇 |
2022年 | 172篇 |
2021年 | 173篇 |
2020年 | 68篇 |
2019年 | 79篇 |
2018年 | 100篇 |
2017年 | 105篇 |
2016年 | 121篇 |
2015年 | 98篇 |
2014年 | 169篇 |
2013年 | 252篇 |
2012年 | 194篇 |
2011年 | 235篇 |
2010年 | 173篇 |
2009年 | 164篇 |
2008年 | 179篇 |
2007年 | 140篇 |
2006年 | 105篇 |
2005年 | 101篇 |
2004年 | 92篇 |
2003年 | 89篇 |
2002年 | 100篇 |
2001年 | 62篇 |
2000年 | 50篇 |
1999年 | 44篇 |
1998年 | 28篇 |
1997年 | 34篇 |
1996年 | 32篇 |
1995年 | 24篇 |
1994年 | 27篇 |
1993年 | 19篇 |
1992年 | 23篇 |
1991年 | 9篇 |
1990年 | 24篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有3467条查询结果,搜索用时 15 毫秒
141.
Farrell RA Kinahan NT Hansel S Stuen KO Petkov N Shaw MT West LE Djara V Dunne RJ Varona OG Gleeson PG Jung SJ Kim HY Koleśnik MM Lutz T Murray CP Holmes JD Nealey PF Duesberg GS Krstić V Morris MA 《Nanoscale》2012,4(10):3228-3236
Extending the resolution and spatial proximity of lithographic patterning below critical dimensions of 20 nm remains a key challenge with very-large-scale integration, especially if the persistent scaling of silicon electronic devices is sustained. One approach, which relies upon the directed self-assembly of block copolymers by chemical-epitaxy, is capable of achieving high density 1?:?1 patterning with critical dimensions approaching 5 nm. Herein, we outline an integration-favourable strategy for fabricating high areal density arrays of aligned silicon nanowires by directed self-assembly of a PS-b-PMMA block copolymer nanopatterns with a L(0) (pitch) of 42 nm, on chemically pre-patterned surfaces. Parallel arrays (5 × 10(6) wires per cm) of uni-directional and isolated silicon nanowires on insulator substrates with critical dimension ranging from 15 to 19 nm were fabricated by using precision plasma etch processes; with each stage monitored by electron microscopy. This step-by-step approach provides detailed information on interfacial oxide formation at the device silicon layer, the polystyrene profile during plasma etching, final critical dimension uniformity and line edge roughness variation nanowire during processing. The resulting silicon-nanowire array devices exhibit Schottky-type behaviour and a clear field-effect. The measured values for resistivity and specific contact resistance were ((2.6 ± 1.2) × 10(5)Ωcm) and ((240 ± 80) Ωcm(2)) respectively. These values are typical for intrinsic (un-doped) silicon when contacted by high work function metal albeit counterintuitive as the resistivity of the starting wafer (~10 Ωcm) is 4 orders of magnitude lower. In essence, the nanowires are so small and consist of so few atoms, that statistically, at the original doping level each nanowire contains less than a single dopant atom and consequently exhibits the electrical behaviour of the un-doped host material. Moreover this indicates that the processing successfully avoided unintentional doping. Therefore our approach permits tuning of the device steps to contact the nanowires functionality through careful selection of the initial bulk starting material and/or by means of post processing steps e.g. thermal annealing of metal contacts to produce high performance devices. We envision that such a controllable process, combined with the precision patterning of the aligned block copolymer nanopatterns, could prolong the scaling of nanoelectronics and potentially enable the fabrication of dense, parallel arrays of multi-gate field effect transistors. 相似文献
142.
Mikhail Yu. Sinev Yurii P. Tulenin Olga V. Kalashnikova Viktor Yu. Bychkov Vladimir N. Korchak 《Catalysis Today》1996,32(1-4):157-162
The analysis of methane oxidation in a wide range of pressures (0.05–10 atm) demonstrates that the efficiency of CH3 radicals recombination is of great importance for high selectivity of C2 hydrocarbons formation. The relative efficiency of different “colliders” assisting the stabilization of exited C2H*6 molecules increases in the series: solid surface> Ar> He. The increase of the overall reaction rate upon increasing pressure of the inert gases in the case of catalysts having a higher surface area and more developed pore structure is likely due to the contribution of the surface-induced chain reaction in the volume of pores. 相似文献
143.
Vladimir Yakushin Maria Misane Oskars Bikovens Dzintra Vilsone Irina Sevastyanova 《Journal of Coatings Technology and Research》2016,13(2):317-324
Tall oil fatty acids (TOFA) were esterified with trimethylolpropane (TMP) without a catalyst at different molar ratios of TMP to TOFA. A molar ratio was defined, at which a polyol stable in long-term storage, with the maximum content of TMP monoesters, was synthesized. Fourier transform infrared spectroscopy and gas chromatography were used for the identification of the polyols’ chemical structure and composition. Based on the synthesized polyols, polyurethane coatings were prepared. The effect of the isocyanate index and concentration of traditional Sn-based and less toxic Bi-based catalysts on the gel time of the polyurethane composition, and the mechanical and thermal properties of the coatings was studied. It was found that the new coatings had high tensile strength and modulus of elasticity, comparable with the strength and modulus of the polyurethane based on diethanolamides of TOFA. The initial temperature of decomposition of these coatings was higher than that of the polyurethanes based on esters of TOFA and a number of uralkyds. The coatings based on TMP esters of TOFA were obtained without the use of solvents, and potentially, these esters can be used in spray-applied VOC-free polyurethane coatings’ formulation. 相似文献
144.
Nadine Reichhart Vladimir M. Milenkovic Christian H. Wetzel Olaf Strauß 《International journal of molecular sciences》2021,22(5)
The anoctamin (TMEM16) family of transmembrane protein consists of ten members in vertebrates, which act as Ca2+-dependent ion channels and/or Ca2+-dependent scramblases. ANO4 which is primarily expressed in the CNS and certain endocrine glands, has been associated with various neuronal disorders. Therefore, we focused our study on prioritizing missense mutations that are assumed to alter the structure and stability of ANO4 protein. We employed a wide array of evolution and structure based in silico prediction methods to identify potentially deleterious missense mutations in the ANO4 gene. Identified pathogenic mutations were then mapped to the modeled human ANO4 structure and the effects of missense mutations were studied on the atomic level using molecular dynamics simulations. Our data show that the G80A and A500T mutations significantly alter the stability of the mutant proteins, thus providing new perspective on the role of missense mutations in ANO4 gene. Results obtained in this study may help to identify disease associated mutations which affect ANO4 protein structure and function and might facilitate future functional characterization of ANO4. 相似文献
145.
Svetlana V. Klinova Boris A. Katsnelson Ilzira A. Minigalieva Oksana P. Gerzen Alexander A. Balakin Ruslan V. Lisin Ksenia A. Butova Salavat R. Nabiev Oleg N. Lookin Leonid B. Katsnelson Larisa I. Privalova Daniil A. Kuznetsov Vladimir Ya. Shur Ekaterina V. Shishkina Oleg H. Makeev Irene E. Valamina Vladimir G. Panov Marina P. Sutunkova Larisa V. Nikitina Yuri L. Protsenko 《International journal of molecular sciences》2021,22(7)
Subchronic intoxication was induced in outbred male rats by repeated intraperitoneal injections with lead oxide (PbO) and/or cadmium oxide (CdO) nanoparticles (NPs) 3 times a week during 6 weeks for the purpose of examining its effects on the contractile characteristics of isolated right ventricle trabeculae and papillary muscles in isometric and afterload contractions. Isolated and combined intoxication with these NPs was observed to reduce the mechanical work produced by both types of myocardial preparation. Using the in vitro motility assay, we showed that the sliding velocity of regulated thin filaments drops under both isolated and combined intoxication with CdO–NP and PbO–NP. These results correlate with a shift in the expression of myosin heavy chain (MHC) isoforms towards slowly cycling β–MHC. The type of CdO–NP + PbO–NP combined cardiotoxicity depends on the effect of the toxic impact, the extent of this effect, the ratio of toxicant doses, and the degree of stretching of cardiomyocytes and muscle type studied. Some indices of combined Pb–NP and CdO–NP cardiotoxicity and general toxicity (genotoxicity included) became fully or partly normalized if intoxication developed against background administration of a bioprotective complex. 相似文献
146.
Ekaterina I. Lesnova Olga V. Masalova Kristina Yu. Permyakova Vyacheslav V. Kozlov Tatyana N. Nikolaeva Alexander V. Pronin Vladimir T. Valuev-Elliston Alexander V. Ivanov Alla A. Kushch 《International journal of molecular sciences》2021,22(13)
Hepatitis C virus (HCV) is one of the main triggers of chronic liver disease. Despite tremendous progress in the HCV field, there is still no vaccine against this virus. Potential vaccines can be based on its recombinant proteins. To increase the humoral and, especially, cellular immune response to them, more effective adjuvants are needed. Here, we evaluated a panel of compounds as potential adjuvants using the HCV NS5B protein as an immunogen. These compounds included inhibitors of polyamine biosynthesis and urea cycle, the mTOR pathway, antioxidants, and cellular receptors. A pronounced stimulation of cell proliferation and interferon-γ (IFN-γ) secretion in response to concanavalin A was shown for antioxidant N-acetylcysteine (NAC), polyamine biosynthesis inhibitor 2-difluoromethylornithine (DFMO), and TLR9 agonist CpG ODN 1826 (CpG). Their usage during the immunization of mice with the recombinant NS5B protein significantly increased antibody titers, enhanced lymphocyte proliferation and IFN-γ production. NAC and CpG decreased relative Treg numbers; CpG increased the number of myeloid-derived suppressor cells (MDSCs), whereas neither NAC nor DFMO affected MDSC counts. NAC and DFMO suppressed NO and interleukin 10 (IL-10) production by splenocytes, while DFMO increased the levels of IL-12. This is the first evidence of immunomodulatory activity of NAC and DFMO during prophylactic immunization against infectious diseases. 相似文献
147.
Ekaterina Sukhova Daria Ratnitsyna Vladimir Sukhov 《International journal of molecular sciences》2021,22(15)
H+-ATP-ases, which support proton efflux through the plasma membrane, are key molecular transporters for electrogenesis in cells of higher plants. Initial activities of the transporters can influence the thresholds of generation of electrical responses induced by stressors and modify other parameters of these responses. Previously, it was theoretically shown that the stochastic heterogeneity of individual cell thresholds for electrical responses in a system of electrically connected neuronal cells can decrease the total threshold of the system (“diversity-induced resonance”, DIR). In the current work, we tested a hypothesis about decreasing the thresholds of generation of cooling-induced electrical responses in a system of electrically connected plant cells with increasing stochastic spatial heterogeny in the initial activities of H+-ATP-ases in these cells. A two-dimensional model of the system of electrically connected excitable cells (simple imitation of plant leaf), which was based on a model previously developed in our works, was used for the present investigation. Simulation showed that increasing dispersion in the distribution of initial activities of H+-ATP-ases between cells decreased the thresholds of generation of cooling-induced electrical responses. In addition, the increasing weakly influenced the amplitudes of electrical responses. Additional analysis showed two different mechanisms of the revealed effect. The increasing spatial heterogeneity in activities of H+-ATP-ases induced a weak positive shift of the membrane potential at rest. The shift decreased the threshold of electrical response generation. However, the decreased threshold induced by increasing the H+-ATP-ase activity heterogeneity was also observed after the elimination of the positive shift. The result showed that the “DIR-like” mechanism also participated in the revealed effect. Finally, we showed that the standard deviation of the membrane potentials before the induction of action potentials could be used for the estimation of thresholds of cooling-induced plant electrical responses. Thus, spatial heterogeneity in the initial activities of H+-ATP-ases can be a new regulatory mechanism influencing the generation of electrical responses in plants under actions of stressors. 相似文献
148.
Alsu Z. Malikova Anastasia S. Shcherbakova Konstantin A. Konduktorov Anastasia S. Zemskaya Alexandra A. Dalina Vladimir I. Popenko Olga G. Leonova Alexei V. Morozov Nikolay N. Kurochkin Olga A. Smirnova Sergey N. Kochetkov Maxim V. Kozlov 《International journal of molecular sciences》2021,22(9)
Recent evidence suggests that fibrotic liver injury in patients with chronic hepatitis C correlates with cellular senescence in damaged liver tissue. However, it is still unclear how senescence can affect replication of the hepatitis C virus (HCV). In this work, we report that an inhibitor of cyclin-dependent kinases 4/6, palbociclib, not only induced in hepatoma cells a pre-senescent cellular phenotype, including G1 arrest in the cell cycle, but also accelerated viral replicon multiplication. Importantly, suppression of HCV replication by direct acting antivirals (DAAs) was barely affected by pre-senescence induction, and vice versa, the antiviral activities of host-targeting agents (HTAs), such as inhibitors of human histone deacetylases (HDACi), produced a wide range of reactions—from a dramatic reduction to a noticeable increase. It is very likely that under conditions of the G1 arrest in the cell cycle, HDACi exhibit their actual antiviral potency, since their inherent anticancer activity that complicates the interpretation of test results is minimized. 相似文献
149.
150.
Plasma-catalysis destruction of aromatics for environmental clean-up: Effect of temperature and configuration 总被引:2,自引:0,他引:2
Alice M. Harling Vladimir Demidyuk Stuart J. Fischer J. Christopher Whitehead 《Applied catalysis. B, Environmental》2008,82(3-4):180-189
A non-thermal, atmospheric pressure, packed-bed plasma reactor has been used to study the effect of temperature on the plasma-catalytic destruction of toluene and benzene in air using two catalyst positions. TiO2 and γ-Al2O3 supports, and Ag (0.5 wt.%) impregnated catalysts of both supports, were used to determine their effects. The reactor (in the one-stage configuration) or the downstream catalyst (in the two-stage arrangement) could be heated to 600 °C and the destruction efficiencies for toluene and benzene were determined. Plasma catalysis is more effective at destroying benzene and toluene than both conventional thermal-catalysis and plasma alone. Toluene is destroyed much more efficiently than benzene, regardless of the temperature of the system and the reactor configuration. A one-stage, plasma-catalysis configuration is found to be more effective at destroying both toluene and benzene than a two-stage configuration. Plasma catalysis offers no advantage over thermal catalysis for destroying both pollutants in the two-stage configuration. 相似文献