全文获取类型
收费全文 | 899篇 |
免费 | 19篇 |
专业分类
电工技术 | 102篇 |
综合类 | 1篇 |
化学工业 | 374篇 |
金属工艺 | 8篇 |
机械仪表 | 12篇 |
建筑科学 | 15篇 |
能源动力 | 41篇 |
轻工业 | 83篇 |
水利工程 | 1篇 |
无线电 | 44篇 |
一般工业技术 | 141篇 |
冶金工业 | 4篇 |
原子能技术 | 31篇 |
自动化技术 | 61篇 |
出版年
2022年 | 13篇 |
2021年 | 21篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 19篇 |
2013年 | 36篇 |
2012年 | 44篇 |
2011年 | 38篇 |
2010年 | 38篇 |
2009年 | 34篇 |
2008年 | 47篇 |
2007年 | 47篇 |
2006年 | 35篇 |
2005年 | 29篇 |
2004年 | 25篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 19篇 |
2000年 | 14篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 26篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1971年 | 3篇 |
排序方式: 共有918条查询结果,搜索用时 15 毫秒
71.
72.
73.
Md. Forhad Mina Md. Akramul Haque Md. Khairul Hassan Bhuiyan Md. Abdul Gafur Yukihiro Tamba Tsutomu Asano 《应用聚合物科学杂志》2010,118(1):312-319
Nanocomposites of isotactic polypropylene (iPP) and multiwalled carbon nanotubes (MWCNTs) with various contents of MWCNTs were fabricated by double molding techniques. X‐ray diffraction measurements reveal a development of α‐crystal with lamellar stacks having a long period of 150 Å in the neat iPP that increases to 165 Å in 2 wt % MWCNTs‐loaded composites, indicating that MWCNTs enhance crystallization of iPP as a nucleating factor. Mechanical properties, such as tensile strength, flexural strength, Young's modulus, tangent modulus, and microhardness are found to increase with increasing MWCNTs content. Thermal analyses represent an increase of crystallization and melting temperatures and a decrease of thermal stability of the composites with increasing MWCNTs. Changes in structural, mechanical, and thermal properties of the composites due to the addition of MWCNTs are elaborately discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
74.
Eiji Kamio Yu Seike Hidekazu Yoshizawa Tsutomu Ono 《American Institute of Chemical Engineers》2010,56(8):2163-2172
The liquid–liquid extraction dynamics of an ethyl ester of docosahexaenoic acid (DHA‐Et) with silver ion was investigated. The kinetic model was derived according to the following stepwise processes: Diffusion of DHA‐Et across the organic film, complex‐formation between DHA‐Et and silver ion at the interface, and diffusion of extracted complex across the aqueous film. The kinetic parameters for the complex‐formation reaction were determined from the investigation with the stirred transfer cell. With the proposed model and determined parameters, we predicted the uptakes of DHA‐Et for the extraction system utilizing a slug flow prepared by a microchip. The calculated uptakes showed good correlation to the experimental data. The theoretical investigation suggested that the fast equilibration realized for the slug flow extraction system was due to the large specific interfacial area of the slug caused by the presence of wall film and the thin liquid film caused by the internal circulation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 相似文献
75.
Yuichi Shimauchi Sachiko Ode Tsutomu Yamazaki Yuta Matsushima Kazuyuki Maeda 《Journal of Porous Materials》2010,17(3):305-312
A new vapor phase transport (VPT) technique to prepare an inverse silica replica of an ordered mesoporous carbon was developed.
Tetraethyl orthosilicate (TEOS) was infiltrated in mesoporous carbon CMK-3 as the hard template at 180 °C for 48 h under an
autogenous pressure in an autoclave in the presence of water. The samples obtained by removal of CMK-3 retained structural
regularity of CMK-3 with little shrinkage of framework, which were characterized by SAXRD, N2 adsorption, TG-DTA, and SEM. Influence of preparation temperature on the loading amount of silica was investigated. The multi-step
replication process was monitored by characterizing the replicated materials as well as intermediate composites. 相似文献
76.
In phosphoric acid fuel cell (PAFC) stack, reduction of the phosphoric acid that is impregnated in the cell is a major factor to restrict the operating life. In this paper, the phosphoric acid reduction by the evaporative and condensational dissipation was evaluated by numerical analysis. The calculations that include the behavior of heat transfer, gas flow, and evaporation and condensation of phosphoric acid were conducted for the model cell with conditions that correspond to an on site stack. The phosphoric acid was considered as a composite of phosphorus pentoxide and water, and the evaporation and condensation rates were derived based on the nucleation theory for a two components system. The phosphoric acid distributions in the vapor phase and liquid phase at the process gas and electrode were calculated for the duration of 3300 h, and as a result of those, the exhausting and remaining amount of phosphoric acid for the cell were evaluated. The analysis results were compared with the experimental results for the model cell. 相似文献
77.
Dr. Shingo Naraki Mai Kakihara Sayuri Kato Dr. Yusuke Saga Dr. Kazuto Mannen Dr. Shohei Takase Dr. Akihito Takano Sayaka Shinpo Dr. Tsutomu Hosouchi Dr. Takahisa Nakane Dr. Hideyuki Suzuki Dr. Tetsuo Kushiro 《Chembiochem : a European journal of chemical biology》2021,22(11):1992-2001
Imperata cylindrica is known to produce a pair of triterpenes, isoarborinol and fernenol, that exhibit identical planar structures but possess opposite stereochemistry at six of the nine chiral centers. These differences arise from a boat or a chair cyclization of the B-ring of the substrate. Herein, we report the characterization of three OSC genes from I. cylindrica. IcOSC1 and IcOSC5 were identified as isoarborinol and fernenol synthases, respectively, while IcOSC3 was characterized as a multifunctional enzyme that produces glutinol and friedelin as its major products. Mutational studies of isoarborinol and fernenol synthases revealed that the residues surrounding the DCTAE motif partially affected the conformation of the B-ring during cyclization. Additionally, the IcOSC1-W255H mutant produced the rare triterpene boehmerol. The introduced histidine residue presumably abstracted a proton from the intermediary carbocation at C18 during the 1,2-rearrangement. Expression analysis indicated that all OSC genes were highly expressed in stems. 相似文献
78.
Tsutomu Tachibana Yuki Nishikawa Nakao Kubo Seiji Takeda 《International journal of molecular sciences》2021,22(1)
Floral organs have evolved from leaves for reproduction, and the morphological analyses help to understand the plant diversity and evolution. Habenaria radiata (syn. Pecteilis radiata) is a terrestrial orchid living in wetlands in Japan, Russia, South Korea, and China. The habitats of this plant in Japan have been reduced because of environmental destruction and overexploitation, and thus it is on the Red List of Japan as a Near Threatened species. One of the three petals of the H. radiata flower is called a lip or labellum, which resembles a flying white bird, egret, or white heron, with its proposed function being to attract pollinators. To understand the diversity of H. radiata plants in different areas, we examined the lip morphology and phylogeny of populations from eight habitats in the Kinki area, Japan. The complex shapes of the lips were quantified and presented as a radar chart, enabling characterization of the morphological difference among populations. Phylogenetic analysis with microsatellite markers that we generated showed the variation of genetic diversity among populations, suggesting the different degrees of inbreeding, outbreeding, and vegetative propagation. Our approach offers a basic method to characterize the morphological and genetic diversity in natural populations. 相似文献
79.
Monolayers of an amphiphilic nitrophenylazide (ANPA) derivative were prepared and their ability to immobilize a protein molecule by a photochemical binding reaction was demonstrated as a novel means to constitute a biofunctional membrane. Molecular orientations and photoreactions in the ANPA monolayers were investigated by Fourier transform IR spectroscopy. Rapid photolysis of ANPA was observed which reflects decomposition of the azide group to a reactive nitrene radical intermediate. As an enzyme, glucose oxidase (GOD) was immobilized on a monomolecular film of ANPA, coated on a substrate, by means of enzyme adsorption at the solid-solution interface and subsequent photolysis of ANPA. Radioisotope labelling experiments revealed that the enzyme was immobilized at a high surface concentration which corresponds to a closely packed monolayer of GOD. The specific activity of the immobilized enzyme was estimated to be high compared with those of other systems involving the adsorption of this enzyme. The usefulness of the present technique for fabricating biofunctional monolayer assemblies is discussed. 相似文献
80.
Multiresidue analysis of pesticides in agricultural products by GC/MS coupled with database software
Ueno E Kabashima Y Oshima H Ohno T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2008,49(4):316-319
We evaluated a multiresidue method for determination of pesticides in agricultural products by SCAN mode GC/MS coupled with three kinds of database for 253 pesticides: relative retention time, mass spectra and calibration curve (SCAN method). Twenty-six pesticides, a total of 131 pesticides were detected in samples by the SCAN method. The detection results agreed closely with those of the SIM mode GC/MS method using calibration standards (SIM method). The ratios of the SCAN method to the SIM method ranged from 0.3 to 3.1 with SD values of 0.63. It was judged that the SCAN method could be applied to the screening analysis of pesticide residues in agricultural products, provided that the sample preparation method makes it possible to effectively remove sample matrixes with minimal loss of analytes. 相似文献