全文获取类型
收费全文 | 109079篇 |
免费 | 20614篇 |
国内免费 | 3419篇 |
专业分类
电工技术 | 5001篇 |
技术理论 | 10篇 |
综合类 | 5049篇 |
化学工业 | 28577篇 |
金属工艺 | 4216篇 |
机械仪表 | 4952篇 |
建筑科学 | 7443篇 |
矿业工程 | 1959篇 |
能源动力 | 2898篇 |
轻工业 | 12393篇 |
水利工程 | 1786篇 |
石油天然气 | 3948篇 |
武器工业 | 606篇 |
无线电 | 15359篇 |
一般工业技术 | 19861篇 |
冶金工业 | 3984篇 |
原子能技术 | 853篇 |
自动化技术 | 14217篇 |
出版年
2024年 | 266篇 |
2023年 | 1198篇 |
2022年 | 2244篇 |
2021年 | 3343篇 |
2020年 | 3757篇 |
2019年 | 4965篇 |
2018年 | 5190篇 |
2017年 | 5548篇 |
2016年 | 5971篇 |
2015年 | 6733篇 |
2014年 | 7424篇 |
2013年 | 9060篇 |
2012年 | 7290篇 |
2011年 | 7370篇 |
2010年 | 6783篇 |
2009年 | 6445篇 |
2008年 | 5946篇 |
2007年 | 5572篇 |
2006年 | 5132篇 |
2005年 | 4413篇 |
2004年 | 3601篇 |
2003年 | 3405篇 |
2002年 | 3230篇 |
2001年 | 2875篇 |
2000年 | 2864篇 |
1999年 | 2510篇 |
1998年 | 1762篇 |
1997年 | 1431篇 |
1996年 | 1395篇 |
1995年 | 1168篇 |
1994年 | 1011篇 |
1993年 | 714篇 |
1992年 | 553篇 |
1991年 | 399篇 |
1990年 | 346篇 |
1989年 | 305篇 |
1988年 | 218篇 |
1987年 | 149篇 |
1986年 | 115篇 |
1985年 | 81篇 |
1984年 | 56篇 |
1983年 | 44篇 |
1982年 | 50篇 |
1981年 | 33篇 |
1980年 | 34篇 |
1979年 | 17篇 |
1977年 | 10篇 |
1976年 | 15篇 |
1974年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays. 相似文献
112.
113.
Alfredo M. Gravagnuolo Eden Morales‐Narváez Charlene Regina Santos Matos Sara Longobardi Paola Giardina Arben Merkoçi 《Advanced functional materials》2015,25(38):6084-6092
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications. 相似文献
114.
Neural Computing and Applications - In this paper, an adaptive neural network (NN) output feedback control is investigated for incommensurate fractional-order permanent magnet synchronous motors... 相似文献
115.
116.
Zhao Hongliang Lu Tingting Liu Fengqin Yin Pan Wang Sen 《JOM Journal of the Minerals, Metals and Materials Society》2019,71(5):1643-1649
JOM - The Isa/Ausmelt smelting technology with a top submerged lance (TSL) has been extensively used in copper smelting processes. However, the TSL is extremely vulnerable to damage and failure... 相似文献
117.
Identification of vivianite,an unusual blue pigment,in a sixteenth century painting and its implications
下载免费PDF全文
![点击此处可从《Color research and application》网站下载免费的PDF全文](/ch/ext_images/free.gif)
António João Cruz Erica Eires Luís Dias Teresa Desterro Carla Rego 《Color research and application》2018,43(2):177-183
Vivianite, a blue pigment employed in the past practically only in Northern and Central Europe, but with very limited use, was identified in an early sixteenth century painting, stylistically with Flemish features, from a church in Portugal. The identification of this iron phosphate mineral was made by SEM‐EDS based on the atomic ratio between phosphorus and iron in layers of blue paint (area analysis) and in particles of these same layers (spot analysis). This painting, about which there is no document to prove its authorship, becomes the first case, known in detail, of a sixteenth century painting containing vivianite. Moreover, this find and the presence of a chalk ground, also identified, strongly support the hypothesis of being a Flemish painting. 相似文献
118.
Mohammad Reza Gaeeni Morteza Sasani Ghamsari Abbas Majd Abadi Mohammad Hossein Majles Ara Wooje Han Hyung‐Ho Park 《Journal of the American Ceramic Society》2015,98(6):1818-1822
A facile sol–gel procedure has been developed for the synthesis of colloidal alumina nanocrystals. For the first time, optical characterization procedures were employed to study the quantum confinement effects in optical properties of the prepared Al2O3 sol. Accordingly, the hyperbolic band model was used to determine the optical band gap of colloidal alumina nanocrystals. X‐Ray diffraction pattern was used to study the crystallographic phase of the dried gel. Morphological characterization was performed using scanning electron microscopy (SEM). Inductively Coupled Plasma (ICP) emission spectroscopy was used to determination purity of the Al2O3 powder. High‐resolution TEM showed that the diameter of colloidal nanocrystals is about 10 nm. Photoluminescence spectroscopy demonstrated that quantum yields for colloidal nanocrystals are 68% with 300 nm excitation wavelength. The experimental observations confirm that highly stable alumina sol with strong UV emission was synthesized. The mentioned optical properties have not been reported before. 相似文献
119.
120.
Isopimaric acid is a typical rosin compound and can account for 30% of the total mass of slash pine rosin. The molecular structure of isopimaric acid derivatives features an unsaturated double bond at the C13 position, opening up the possibility of their industrial polymerization. In this study, isopimaric acid (95.4%), methyl isopimarate (99.5%), and allyl isopimarate (95.1%) were prepared as highly pure monomers. New experimental results are presented and mechanisms based on the investigation of free-radical polymerization under UV irradiation are proposed. New rosin monomers for potential value-added utilization of woody biomass are also identified. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47817. 相似文献