全文获取类型
收费全文 | 1470篇 |
免费 | 74篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 20篇 |
综合类 | 13篇 |
化学工业 | 419篇 |
金属工艺 | 22篇 |
机械仪表 | 21篇 |
建筑科学 | 121篇 |
矿业工程 | 5篇 |
能源动力 | 41篇 |
轻工业 | 94篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 89篇 |
一般工业技术 | 302篇 |
冶金工业 | 76篇 |
原子能技术 | 9篇 |
自动化技术 | 309篇 |
出版年
2023年 | 16篇 |
2022年 | 11篇 |
2021年 | 32篇 |
2020年 | 38篇 |
2019年 | 34篇 |
2018年 | 44篇 |
2017年 | 17篇 |
2016年 | 41篇 |
2015年 | 31篇 |
2014年 | 72篇 |
2013年 | 89篇 |
2012年 | 84篇 |
2011年 | 143篇 |
2010年 | 86篇 |
2009年 | 72篇 |
2008年 | 79篇 |
2007年 | 77篇 |
2006年 | 69篇 |
2005年 | 44篇 |
2004年 | 50篇 |
2003年 | 38篇 |
2002年 | 42篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 21篇 |
1998年 | 31篇 |
1997年 | 34篇 |
1996年 | 14篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1970年 | 4篇 |
1954年 | 3篇 |
排序方式: 共有1545条查询结果,搜索用时 15 毫秒
1.
Volker Kahlenberg Johan P.R. de Villiers Dirk Odendaal Hannes Krüger Shengqiang Song Mithun Nath 《Journal of the American Ceramic Society》2019,102(11):6968-6979
Polycrystalline material of a novel phase in the system CaO–Al2O3–Cr2O3 has been obtained by solid-state reactions. Chemical analysis indicated the composition CaAl2Cr2O7. Single-crystal growth of the new compound using borax as a mineralizer was successful. Diffraction experiments at ambient conditions on a crystal with composition CaAl2.13Cr1.87O7 yielded the following basic crystallographic data: space group P 3, a = 7.7690(5) Å, c = 7.6463(5) Å, V = 399.68(6) Å3, Z = 3. Structure determination and subsequent least-squares refinements resulted in a residual of R(|F|) = 2.3% for 1440 independent observed reflections and 113 parameters. To the best of our knowledge, the structure of CaAl2.13Cr1.87O7 or CaAl2Cr2O7 represents a new structure type. It belongs to the group of double layer structures where individual double layers contain octahedrally and tetrahedrally coordinated cation positions. Linkage between neighboring sheet packages is provided by additional calcium cations. Furthermore, thermal expansion has been studied in the interval between 29 and 790°C using in situ high-temperature single-crystal diffraction. No indications for a structural phase transition were observed. From the evolution of the lattice parameters the thermal expansion tensor has been obtained. A pronounced anisotropy is evident. The response of structural building units to variable temperature has been discussed. 相似文献
2.
Marcus Weyd Christian Pflieger Andy Vogel Hannes Richter Volker Prehn Christiane Günther Frank Splittgerber Alessa Gäbler Daniel Kaulbars Patrick Bräutigam Marcus Franke Samira Lambertz Julian Schlechtweg Ingolf Voigt 《化学,工程师,技术》2021,93(9):1432-1439
Reducing micropollutant pollution of water bodies is an important objective of water management and an integral part of environmental policy. Ceramic nanofiltration membranes were developed as multichannel membranes of increased membrane area and rotating disk filters. The membranes developed show retention of over 80 % for PEG 400. The membranes are currently being tested for the separation of micropollutants from wastewater contaminated with pharmaceuticals. With the help of a downstream oxidative process, the trace substances remaining in the permeate are degraded. 相似文献
3.
Leentje Volker 《Construction Management & Economics》2019,37(1):13-23
In reaction to the recent call for critical debate in the field of construction management research, I argue that we should embrace the richness of adjacent fields of study in order to dynamically develop our own and face the plethora of contemporary societal challenges that exist in our industry. I introduce the concepts of other-than-rational thinking in decision-making and multiplicity in management responses as examples of inspirational sources from social sciences that would contribute to truly understanding the driving forces of construction management processes. I connect these concepts to contemporary studies in construction management and share my experiences with several positive collaborative approaches in conducting construction management research. 相似文献
4.
Zhenzhen Zhang Md. Mushfequr Rahman Clarissa Abetz Anke-Lisa Höhme Evgeni Sperling Volker Abetz 《Advanced materials (Deerfield Beach, Fla.)》2020,32(8):1907014
Membrane-based separation of organic molecules with 1–2 nm lateral dimensions is a demanding but rather underdeveloped technology. The major challenge is to fabricate membranes having distinct nanochannels with desired functionality. Here, a bottom-up strategy to produce such a membrane using a tailor-made triblock terpolymer featuring miscible end blocks with two different functional groups is demonstrated. A scalable multifunctional integral asymmetric isoporous membrane is fabricated by the solvent evaporation-induced self-assembly of the block copolymer combined with nonsolvent-induced phase separation. The membrane nanopores are readily functionalized using positively and negatively charged moieties by two straightforward gas–solid reactions. The pores of the post-functionalized membranes act as target-specific functional soft nanochannels due to swelling of the polyelectrolyte blocks in a hydrated state. The membranes show unprecedented separation selectivity of small molecules based on size and/or charge which demonstrates the potential of the proposed strategy to prepare next-generation nanofiltration membranes. 相似文献
5.
Measurements of ice recrystallization inhibition (IRI) and thermal hysteresis (TH) activities of kappa (κ)- and iota (ι)-carrageenans were carried out to examine whether they can be novel cryoprotectants or not. IRI measurements indicate that both carrageenans reduce recrystallization in sucrose solution, but that the IRI activity of κ-carregeenan is higher than that of ι-carrageenan. TH measurements indicate that κ- and ι-carrageenans do not exhibit TH activity. TH activity measurements of antifreeze glycoprotein (AFGP) in the presence of κ-carregeenan demonstrate that this carregeenan neither influences the TH activity of AFGP nor the shape of the ice crystals. The round ice crystal shape transformed into an angular and elongated shape in the presence of both carregeenans. 相似文献
6.
7.
Jasmin Balmer Rahel Zulliger Stefano Roberti Volker Enzmann 《International journal of molecular sciences》2015,16(7):15086-15103
Herein, we have investigated retinal cell-death pathways in response to the retina toxin sodium iodate (NaIO3) both in vivo and in vitro. C57/BL6 mice were treated with a single intravenous injection of NaIO3 (35 mg/kg). Morphological changes in the retina post NaIO3 injection in comparison to untreated controls were assessed using electron microscopy. Cell death was determined by TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining. The activation of caspases and calpain was measured using immunohistochemistry. Additionally, cytotoxicity and apoptosis in retinal pigment epithelial (RPE) cells, primary retinal cells, and the cone photoreceptor (PRC) cell line 661W were assessed in vitro after NaIO3 treatment using the ApoToxGlo™ assay. The 7-AAD/Annexin-V staining was performed and necrostatin (Nec-1) was administered to the NaIO3-treated cells to confirm the results. In vivo, degenerating RPE cells displayed a rounded shape and retracted microvilli, whereas PRCs featured apoptotic nuclei. Caspase and calpain activity was significantly upregulated in retinal sections and protein samples from NaIO3-treated animals. In vitro, NaIO3 induced necrosis in RPE cells and apoptosis in PRCs. Furthermore, Nec-1 significantly decreased NaIO3-induced RPE cell death, but had no rescue effect on treated PRCs. In summary, several different cell-death pathways are activated in retinal cells as a result of NaIO3. 相似文献
8.
9.
Joseph Isimite Frank Baganz Volker C Hass 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2018,93(6):1529-1541
Recent technological advances in the development of alternative energy sources, including biofuels, for transportation and energy requirements have demonstrated the need for highly skilled engineers and operators in the biotechnological industries. Although operator training simulators (OTS) used in the traditional chemical process industries may be used to train biorefinery operators and engineers, several distinct aspects of bioprocess operations make their direct application limited. The development and deployment of OTSs for use in biotechnological processes is therefore beginning to gain increasing attention. This review paper examines the present status of OTS development and use in biorefineries, including future considerations on how an OTS may be used to improve operator competence, maximise biorefinery operational efficiencies and protect people and the environment. The general premise of an OTS is that model‐based operator training simulators can be used to verifiably enhance the training of industrial operators to run complex biorefineries. Only a few examples of the design and application of OTSs in large‐scale biorefineries have so far been reported. A discussion of the mathematical models used for OTS development is briefly presented, as well as available OTS design frameworks and vendors, including their benefits and drawbacks. The review concludes by looking at possible future directions of OTS development and use in biorefineries and their contribution in facilitating the transition to a bio‐based economy. © 2018 Society of Chemical Industry 相似文献
10.
Kritika Sharma Tim U. Krohne Volker Busskamp 《International journal of molecular sciences》2020,21(22)
Retinal degenerative diseases lead to irreversible blindness. Decades of research into the cellular and molecular mechanisms of retinal diseases, using either animal models or human cell-derived 2D systems, facilitated the development of several therapeutic interventions. Recently, human stem cell-derived 3D retinal organoids have been developed. These self-organizing 3D organ systems have shown to recapitulate the in vivo human retinogenesis resulting in morphological and functionally similar retinal cell types in vitro. In less than a decade, retinal organoids have assisted in modeling several retinal diseases that were rather difficult to mimic in rodent models. Retinal organoids are also considered as a photoreceptor source for cell transplantation therapies to counteract blindness. Here, we highlight the development and field’s improvements of retinal organoids and discuss their application aspects as human disease models, pharmaceutical testbeds, and cell sources for transplantations. 相似文献