全文获取类型
收费全文 | 1012篇 |
免费 | 51篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 348篇 |
金属工艺 | 12篇 |
机械仪表 | 14篇 |
建筑科学 | 59篇 |
能源动力 | 15篇 |
轻工业 | 202篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 53篇 |
一般工业技术 | 155篇 |
冶金工业 | 59篇 |
原子能技术 | 4篇 |
自动化技术 | 131篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 43篇 |
2021年 | 42篇 |
2020年 | 38篇 |
2019年 | 18篇 |
2018年 | 30篇 |
2017年 | 26篇 |
2016年 | 31篇 |
2015年 | 31篇 |
2014年 | 42篇 |
2013年 | 72篇 |
2012年 | 64篇 |
2011年 | 70篇 |
2010年 | 66篇 |
2009年 | 60篇 |
2008年 | 57篇 |
2007年 | 55篇 |
2006年 | 49篇 |
2005年 | 51篇 |
2004年 | 35篇 |
2003年 | 22篇 |
2002年 | 25篇 |
2001年 | 11篇 |
2000年 | 22篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1934年 | 3篇 |
排序方式: 共有1065条查询结果,搜索用时 15 毫秒
31.
This work is a comprehensive study of the effect of extrusion process parameters and formulation on the properties of polypropylene (PP)/short flax fiber composites. The parameters that were varied during the twin‐screw extrusion process were screw configuration, revolutions per minute (rpm), extrusion temperature, and flow rate. The effect of the feeding zone location of cellulosic fiber was also considered. This study investigates the effect of the formulation, cellulosic fiber content, the presence of a coupling agent, and of a reactive additive on composite performance. The composites were characterized in terms of morphology and microstructure, fiber length, rheological, thermal, and mechanical properties. Sensibility to humidity and recyclability were also considered. When compared with as‐received PP, the tensile strength of injection‐molded parts increased with cellulosic content by up to 40 vol %, and the tensile modulus increased 3.5 times when a combination of coupling and reactive agents was used. Exposed to controlled humidity of 50% during 1 year, these composites exhibited a very low level of humidity uptake around 0.85 wt %. The processability of these materials using a cast film line and the mechanical properties of extruded sheets are also presented. Furthermore, these materials demonstrate a good recyclability using injection molding by keeping the integrality of their mechanical properties after five reprocessing cycles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41528. 相似文献
32.
Grard Delahay Stphane Kieger Nathalie Tanchoux Philippe Trens Bernard Coq 《Applied catalysis. B, Environmental》2004,52(4):251-257
The kinetics of the selective catalytic reduction (SCR) of NO by NH3 in the presence of O2 has been studied on a 5.5% Cu-faujasite (Cu-FAU) catalyst. Cu-FAU was composed of cationic and oxocationic Cu species. The SCR was studied in a gas phase-flowing reactor operating at atmospheric pressure. The reaction conditions explored were: 458<TR<513 K, 2503 (ppm) < 4000, 12 (%) < 4. The kinetic orders were 0.8–1 with respect to NO, 0.5–1 with respect to O2, and essentially 0 with respect to NH3. Based on these kinetic partial orders of reactions and elementary chemistry, a wide variety of mechanisms were explored, and different rate laws were derived. The best fit between the measured and calculated rates for the SCR of NO by NH3 was obtained with a rate law derived from a redox Mars and van Krevelen mechanism. The catalytic cycle is described by a sequence of three reactions: (i) CuI is oxidized by O2 to “CuII-oxo”, (ii) “CuII-oxo” reacts with NO to yield “CuII-NxOy”, and (iii) finally “CuII-NxOy” is reduced by NH3 to give N2, H2O, and the regeneration of CuI (closing of the catalytic cycle). The rate constants of the three steps have been determined at 458, 483, and 513 K. It is shown that CuI or “CuII-oxo” species constitute the rate-determining active center. 相似文献
33.
Declerck Nathalie; Machius Mischa; Joyet Philippe; Wiegand Georg; Huber Robert; Gaillardin Claude 《Protein engineering, design & selection : PEDS》2003,16(4):287-293
Bacillus licheniformis 相似文献
34.
35.
Martine Dhilly Javier Becerril‐Ortega Dr. Nathalie Colloc'h Dr. Eric T. MacKenzie Dr. Louisa Barré Prof. Alain Buisson Dr. Olivier Nicole Dr. Cécile Perrio 《Chembiochem : a European journal of chemical biology》2013,14(6):759-769
GluN2B‐containing NMDA receptors are involved in many important physiological functions and play a pivotal role in mediating pain as well as in several neurodegenerative disorders. We aimed to develop fluorescent probes to target the GluN2B subunit selectively in order to allow better understanding of the relationships between receptor localisation and physiological importance. Ifenprodil, known as the GluNR2B antagonist of reference, was chosen as the template for the elaboration of probes. We had previously reported a fluorescein conjugate that was shown (by confocal microscopy imaging of DS‐red‐labelled cortical neurons) to bind specifically to GluN2B. To elaborate this probe, we explored the influence of both the nature and the attachment point of the spacer between the fluorophore and the parent compound, ifenprodil. We performed chemical modifications of ifenprodil at the benzylic position and on the phenol ring by introducing secondary amine or amide functions and evaluated alkyl chains from two to 20 bonds either including or not including secondary amide functions as spacers. The previously developed probe was found to display the greatest activity in the inhibition of NMDA‐induced Ca2+ influx by calcium imaging experiments on HEK293 cells transfected with the cDNA encoding for GluN1‐1A and GluN2B. Further investigations revealed that this probe had a neuroprotective effect equivalent to that of ifenprodil in a standard test for neurotoxicity. Despite effects of lesser amplitude with these probes relative to ifenprodil, we demonstrated that they displaced [3H]ifenprodil in mouse brain slices in a similar manner. 相似文献
36.
Hichem Mallek Corinne Jegat Nathalie Mignard Majdi Abid Souhir Abid Mohamed Taha 《应用聚合物科学杂志》2013,129(3):954-964
Poly(ε‐caprolactone) (PCL)‐based thermoreversible networks with self‐healing properties were prepared through Diels–Alder (DA) and retro‐DA reactions. Bis‐ or Tris‐maleimide compounds and a series of copolymer(caprolactone‐diene) PCLXFY (X: degree of polymerization and Y: furan‐average functionality) with Y between 2.4 and 4.9 were used. The successive sequences of formation and dissociation of polycaprolactone networks via DA and retro‐DA reactions were observed repeatedly by dynamic mechanical analyses (DMA) and their gel‐temperatures determined. The cross‐linking densities, thermal properties, and thermal reversibility of the PCLXFY/multimaleimide polymers have been modulated by the structure and functionalities of the used diene and dienophile moieties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
37.
38.
Zamzam Awida Almog Bachar Hussam Saed Anton Gorodov Nathalie Ben-Califa Maria Ibrahim Albert Kolomansky Jennifer Ana Iden Liad Graniewitz Visacovsky Tamar Liron Sahar Hiram-Bab Michael Brines Yankel Gabet Drorit Neumann 《International journal of molecular sciences》2022,23(1)
The two erythropoietin (EPO) receptor forms mediate different cellular responses to erythropoietin. While hematopoiesis is mediated via the homodimeric EPO receptor (EPOR), tissue protection is conferred via a heteromer composed of EPOR and CD131. In the skeletal system, EPO stimulates osteoclast precursors and induces bone loss. However, the underlying molecular mechanisms are still elusive. Here, we evaluated the role of the heteromeric complex in bone metabolism in vivo and in vitro by using Cibinetide (CIB), a non-erythropoietic EPO analogue that exclusively binds the heteromeric receptor. CIB is administered either alone or in combination with EPO. One month of CIB treatment significantly increased the cortical (~5.8%) and trabecular (~5.2%) bone mineral density in C57BL/6J WT female mice. Similarly, administration of CIB for five consecutive days to female mice that concurrently received EPO on days one and four, reduced the number of osteoclast progenitors, defined by flow cytometry as Lin−CD11b−Ly6Chi CD115+, by 42.8% compared to treatment with EPO alone. In addition, CIB alone or in combination with EPO inhibited osteoclastogenesis in vitro. Our findings introduce CIB either as a stand-alone treatment, or in combination with EPO, as an appealing candidate for the treatment of the bone loss that accompanies EPO treatment. 相似文献
39.
Novel monomers 1a, 1b, in which a phosphonate function is incorporated in both aromatic rings, were synthesized from the addition reaction of tetraisopropyl [2,2′-disulfanyl-5,5′-thiodiphenyl]-1,1′-diphosphonate and diisopropyl (2-sulfanylphenyl)-1-phosphonate with the glycidylmethacrylate. Free radical homo- and copolymerizations of phosphonate monomers containing methacrylate groups were first carried out in bulk and in THF solution. They offered (co)polymers for potential use in dental resins, in high yields and moderate to high inherent viscosities. The components and structure of the (co)polymers were confirmed by FTIR, SEC, 1H, 31P NMR spectra.
Thermal analysis by using differential scanning calorimetry indicated an amorphous structure of the (co)polymers obtained by polymerization in solution. Upon UV-radiation the composite resins have been synthesized by cross-linking reaction. 相似文献
40.
Kinetic data acquisition and screening of transition metal complexes for homogeneous liquid phase catalysis calls for numerous testing in multiphase G/L, L/L and G/L/L systems. It is shown first, with an example in asymmetric hydrogenation, why detailed kinetics must be performed. Then, new reactors leading to fast experimental techniques are proposed. A liquid–liquid centrifugal partition chromatography is evaluated for determining rate constants and partition isotherms by combining frontal analysis and elution chromatography, the catalyst being maintained in a stationary aqueous phase. Two microreactors offering short residence time have also been tested and compared with a fast test reaction (tR ca. 5–20 s). The combination of reacting pulses, carrier liquids and micromixer is proposed as a general high throughput tool for the investigation of G/L, L/L and G/L/L catalytic systems in a fast sequential way. 相似文献