全文获取类型
收费全文 | 904篇 |
免费 | 81篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 28篇 |
化学工业 | 239篇 |
金属工艺 | 9篇 |
机械仪表 | 19篇 |
建筑科学 | 22篇 |
能源动力 | 38篇 |
轻工业 | 257篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
无线电 | 64篇 |
一般工业技术 | 106篇 |
冶金工业 | 69篇 |
原子能技术 | 4篇 |
自动化技术 | 122篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 37篇 |
2020年 | 39篇 |
2019年 | 30篇 |
2018年 | 39篇 |
2017年 | 41篇 |
2016年 | 29篇 |
2015年 | 35篇 |
2014年 | 46篇 |
2013年 | 98篇 |
2012年 | 64篇 |
2011年 | 68篇 |
2010年 | 54篇 |
2009年 | 43篇 |
2008年 | 43篇 |
2007年 | 35篇 |
2006年 | 40篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 21篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有990条查询结果,搜索用时 15 毫秒
1.
García-Peñalvo Francisco J. Moreno Lourdes 《Universal Access in the Information Society》2019,18(1):1-2
Universal Access in the Information Society - 相似文献
2.
Meza-Espinoza Libier de los Ángeles Vivar-Vera María de Lourdes García-Magaña María Sáyago-Ayerdi Sonia G. Chacón-López Alejandra Becerrea-Verdín Eduardo M. Montalvo-González Efigenia 《Food science and biotechnology》2018,27(2):509-517
Food Science and Biotechnology - The enzymatic activity and partial characterization of proteases from Bromelia karatas fruits were evaluated and compared with Bromelia pinguin proteases. The... 相似文献
3.
Dr. André L. C. S. Nascimento Richard P. Fernandes Christian Quijia Victor H. S. Araujo Juliana Pereira Prof. Dr. Jerusa S. Garcia Prof. Dr. Marcello G. Trevisan Prof. Dr. Marlus Chorilli 《ChemMedChem》2020,15(12):1018-1029
Since the beginning of the HIV epidemic, research has been carried out to control the virus. Understanding the mechanisms of replication has given access to the various classes of drugs that over time have transformed AIDS into a manageable chronic disease. The class of protease inhibitors (PIs) gained notice in anti-retroviral therapy, once it was found that peptidomimetic molecules act by blocking the active catalytic center of the aspartic protease, which is directly related to HIV maturation. However, mutations in enzymatic internal residues are the biggest issue for these drugs, because a small change in biochemical interaction can generate resistance. Low plasma concentrations of PIs favor viral natural selection; high concentrations can inhibit even partially resistant enzymes. Food-drug/drug-drug interactions can decrease the bioavailability of PIs and are related to many side effects. Therefore, this review summarizes the pharmacokinetic properties of current PIs, the changes when pharmacological boosters are used and also lists the major mutations to help understanding of how long the continuous treatment can ensure a low viral load in patients. 相似文献
4.
In this work, we study the capacitive properties of gel-type natural abundant polymers without any dopants, mainly commercial gelatin and agar in deionized water. Here, we propose a facile fabrication of flexible, transparent, and planar electrolytic capacitors using these gel-type and indium tin oxide thin films as electrodes deposited on poly(ethylene terephthalate) substrates. Through cyclic voltammetry and galvanostatic charge–discharge techniques, we found that the devices show a specific capacitance in the order of the millifarads per gram, a specific power of ~10 mW cm−2, which is sufficient to active low-power devices, and a life cycle with nearly 100% efficiency after 1,000 cycles. We found that we do not need to add dopants that improve the ionic conductivity of the natural polyelectrolytes to obtain capacitances within the millifarads per gram. The flexibility of the capacitors was demonstrated by bending them, after which they exhibited the same electrochemical performance as the unbent devices. The optical transparency of the capacitors was measured by UV–V is spectroscopy showing a high transmittance in the visible region. 相似文献
5.
Abraham G. Alvarado Rosaura Hernández-Montelongo Martin Rabelero Lourdes A. Pérez-Carrillo Jorge E. Puig Francisco López-Serrano 《Polymer Engineering and Science》2020,60(2):223-232
A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately describes the overall and instantaneous conversion, the average particle density and diameter, and the number and weight average molar masses evolutions over time. It is found that even though the average number of radicals is much smaller than 0.5, the system is not 0-1. An empirical function was used to describe the gel effect. The homogeneous nucleation was the prevailing mechanism for particle formation and large exit rates of radicals were observed. POLYM. ENG. SCI., 60: 223–232, 2019. © 2019 Society of Plastics Engineers 相似文献
6.
Juana Maria de Lourdes Medina-Contreras Patrick Mailloux-Salinas Juventino III Colado-Velazquez Norma Leticia Gomez Viquez Gómez-Viquez Rodrigo Velázquez-Espejel Ana del Carmen Susunaga-Notario David Julian Arias-Chávez Guadalupe Bravo 《Journal of the science of food and agriculture》2020,100(7):3212-3219
7.
Marta Gabasa Marselina Arshakyan Alejandro Llorente Lourdes Chuli-Peris Irina Pavelescu Antoni Xaubet Javier Pereda Jordi Alcaraz 《International journal of molecular sciences》2020,21(22)
Pro-inflammatory cytokines like interleukin-1β (IL-1β) are upregulated during early responses to tissue damage and are expected to transiently compromise the mechanical microenvironment. Fibroblasts are key regulators of tissue mechanics in the lungs and other organs. However, the effects of IL-1β on fibroblast mechanics and functions remain unclear. Here we treated human pulmonary fibroblasts from control donors with IL-1β and used Atomic Force Microscopy to unveil that IL-1β significantly reduces the stiffness of fibroblasts concomitantly with a downregulation of filamentous actin (F-actin) and alpha-smooth muscle (α-SMA). Likewise, COL1A1 mRNA was reduced, whereas that of collagenases MMP1 and MMP2 were upregulated, favoring a reduction of type-I collagen. These mechanobiology changes were functionally associated with reduced proliferation and enhanced migration upon IL-1β stimulation, which could facilitate lung repair by drawing fibroblasts to sites of tissue damage. Our observations reveal that IL-1β may reduce local tissue rigidity by acting both intracellularly and extracellularly through the downregulation of fibroblast contractility and type I collagen deposition, respectively. These IL-1β-dependent mechanical effects may enhance lung repair further by locally increasing pulmonary tissue compliance to preserve normal lung distension and function. Moreover, our results support that IL-1β provides innate anti-fibrotic protection that may be relevant during the early stages of lung repair. 相似文献
8.
9.
Nima R. Alkhorshid Gregório L.S. Araujo Ennio M. Palmeira Jorge G. Zornberg 《Geotextiles and Geomembranes》2019,47(5):632-641
Stone columns have been used to minimize the settlement of embankments on soft soils but their use in very soft soils can become challenging, partly because of the low confinement provided by the surrounding soil. Geosynthetic encased columns (GECs) have been successfully used to enhance to reduce settlements of embankments on soft soils. This paper describes an investigation on the performance of encased columns constructed on a very soft soil using different types of encasement (three woven geotextiles with different values of tensile stiffness) and different column fill materials (sand, gravel and recycled construction and demolition waste, RCDW). The results of load capacity tests conducted on large-scale models constructed to simulate the different types of GECs indicate that the displacement method adopted during column installation can lead to an enhanced shear strength in the smear zone that develops within the very soft soil. In addition, breakage of the column fill material was found to affect the load-settlement response of gravel and RCDW columns. Furthermore, the excess pore water pressure generated in the surrounding soil during installation, was found to remain limited to radial distances smaller than three times the GEC diameter. 相似文献
10.
Lourdes Prez Aurora Pinazo M. C. Morn Ramon Pons 《International journal of molecular sciences》2020,21(23)
The surface activity, aggregates morphology, size and charge characteristics of binary catanionic mixtures containing a cationic amino acid-derived surfactant N(π), N(τ)-bis(methyl)-L-Histidine tetradecyl amide (DMHNHC14) and an anionic surfactant (the lysine-based surfactant Nα-lauroyl-Nεacetyl lysine (C12C3L) or sodium myristate) were investigated for the first time. The cationic surfactant has an acid proton which shows a strong pKa shift irrespective of aggregation. The resulting catanionic mixtures exhibited high surface activity and low critical aggregation concentration as compared with the pure constituents. Catanionic vesicles based on DMHNHC14/sodium myristate showed a monodisperse population of medium-size aggregates and good storage stability. According to Small-Angle X-Ray Scattering (SAXS), the characteristics of the bilayers did not depend strongly on the system composition for the positively charged vesicles. Negatively charged vesicles (cationic surfactant:myristate ratio below 1:2) had similar bilayer composition but tended to aggregate. The DMHNHC14-rich vesicles exhibited good antibacterial activity against Gram-positive bacteria and their bactericidal effectivity declined with the decrease of the cationic surfactant content in the mixtures. The hemolytic activity and cytotoxicity of these catanionic formulations against non-tumoral (3T3, HaCaT) and tumoral (HeLa, A431) cell lines also improved by increasing the ratio of cationic surfactant in the mixture. These results indicate that the biological activity of these systems is mainly governed by the cationic charge density, which can be modulated by changing the cationic/anionic surfactant ratio in the mixtures. Remarkably, the incorporation of cholesterol in those catanionic vesicles reduces their cytotoxicity and increases the safety of future biomedical applications of these systems. 相似文献