全文获取类型
收费全文 | 620篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 44篇 |
综合类 | 2篇 |
化学工业 | 180篇 |
金属工艺 | 21篇 |
机械仪表 | 18篇 |
建筑科学 | 13篇 |
能源动力 | 35篇 |
轻工业 | 56篇 |
水利工程 | 3篇 |
无线电 | 37篇 |
一般工业技术 | 117篇 |
冶金工业 | 29篇 |
原子能技术 | 31篇 |
自动化技术 | 51篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 38篇 |
2012年 | 26篇 |
2011年 | 30篇 |
2010年 | 35篇 |
2009年 | 35篇 |
2008年 | 47篇 |
2007年 | 34篇 |
2006年 | 24篇 |
2005年 | 32篇 |
2004年 | 31篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 19篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有637条查询结果,搜索用时 31 毫秒
51.
Renato Martins da Silva Bárbara Della Noce Camila Fernanda Waltero Evenilton Pessoa Costa Leonardo Araujo de Abreu Naftaly Wang’ombe Githaka Jorge Moraes Helga Fernandes Gomes Satoru Konnai Itabajara da Silva Vaz Jr. Kazuhiko Ohashi Carlos Logullo 《International journal of molecular sciences》2015,16(1):1821-1839
52.
Sobi Asako Takahisa Sakae Masahito Murai Kazuhiko Takai 《Advanced Synthesis \u0026amp; Catalysis》2016,358(24):3966-3970
Mild and simple catalytic systems consisting of molybdenum(VI) dichloride dioxide [MoO2Cl2] as a catalyst and a phosphine as reductant have been developed for the stereospecific deoxygenation of epoxides to alkenes. The reactions using 1,2‐bis(diphenylphosphino)ethane (dppe) and triphenylphosphine (PPh3) proceed with retention and inversion of stereochemistry, respectively. The mild reaction tolerates the presence of various functional groups and affords stereodefined substituted olefins in good yields.
53.
For the construction of a microwave-assisted organic synthesis plant, it is necessary to know the dielectric properties of the reaction system. Measurements of the dielectric properties of lactic acid aqueous solution, anhydrated lactic acid, oligo(lactic acid) and water, which are constituent materials in the polycondensation of lactic acid, confirm that dielectric properties decrease as reaction progresses. Calculated microwave penetration depths, obtained from the dielectric properties, show that microwaves penetrate deeply into the reaction system. This work should be useful for the development of microwave-assisted organic syntheses in the chemical industry. 相似文献
54.
Uematsu Y Ogimoto M Kabashima J Suzuki K Kaneko R Funayama K Haneishi N Yasuno T Ogino S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2005,46(4):133-138
Migration from multi-layer laminated film pouches intended for retort foods was investigated through HPLC analysis with a fluorescence detector, and measurements of residue on evaporation, consumption of potassium permanganate and total organic carbon. HPLC analysis revealed that the levels of migrants in oil and the water which were heated in the pouches (121 degrees C, 30 min) were ten times of those in the corresponding official simulants under the official conditions; n-heptane (25 degrees C, 60 min), and water (95 degrees C, 30 min). Bisphenol A diglycidyl ether and related compounds were found in the oil and the water heated in the pouches, as well as in the simulants. These compounds were thought to have been present in the adhesive between the laminated films, and migrated through the food-contact film of the package. Consumption of potassium permanganate and residue on evaporation of the heated water were ten times of those of the water simulant, while the total organic carbon level of the heated water was several-hold greater than that of the water simulant. In addition, migrant levels per surface area of the pouch were one-fourth of the concentrations per content volume of the pouch. Since compliance with the legal limits is evaluated based on the concentration per surface area, real migration into foods would be underestimated by a factor of another four. 相似文献
55.
Akutsu K Hori S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(4):175-183
Polybrominated diphenyl ethers (PBDEs) have been used worldwide as additive flame retardants in polymeric materials. Commercial products consist predominantly of deca-, octa-, and pentabromodiphenyl ether mixtures. PBDEs are resistant to degradation in the natural environment and Penta-BDE in particular accumulates in the fatty tissues of fish, birds and mammals (including humans). Several toxic effects on the thyroid system or on neurodevelopment have been reported in experimental animals exposed to PBDEs. It is likely that human exposure is predominantly through the ingestion of contaminated food and/or mother's milk. The potential health effects of dietary exposure to PBDEs have now become a great concern because of the increasing PBDE levels in the biosphere. In this review, published information on the toxicology of PBDEs, levels in foodstuffs and human milk, and analytical methods has been compiled. 相似文献
56.
Toshiaki Arai Narihiro Morosawa Kazuhiko Tokunaga Yasuhiro Terai Eri Fukumoto Takashige Fujimori Tatsuya Sasaoka 《Journal of the Society for Information Display》2011,19(2):205-211
Abstract— The stability and reliability of oxide‐semiconductor TFTs were investigated. The contact material to the oxide semiconductor affected the thermal stability of the TFT, and a molybdenum‐contact source/drain showed good stability. And the passivating film and TFT structure affected the stability against bias stress and humidity stress, and dc‐sputtered Al2O3 passivation and fully covered channel structure with an etching stopper or source/drain showed good reliability. Moreover, high photo‐stability was confirmed by the bias‐enhanced photo‐irradiation stress test. An 11.7‐in.‐diagonal qHD AMOLED display was demonstrated to provide an applicable solution for a large‐sized OLED and an ultra‐high‐definition LCD‐TV mass production. 相似文献
57.
Kazuhiko Suzuki S. Seto A. Iwata M. Bingo T. Sawada K. Imai 《Journal of Electronic Materials》2000,29(6):704-707
The electron drift mobility of undoped Cd0.9Zn0.1Te grown by high-pressure Bridgman method is measured by a time-of-flight technique. The sample shows a room temperature mobility
and mobility lifetime product of 950 cm2/Vs and 1.6 × 10−4cm2/V, respectively. The mobility increases monotonically with decreasing temperature to 3000 cm2/Vs at 100 K. The dominant scattering mechanism for the electron transport is discussed by comparing with the theoretical
mobility obtained by iterative solution of the Boltzmann equation. 相似文献
58.
The heterogeneous nature of hardwood lignin was shown by visualizing the deposition process of p-hydroxyphenyl (H) lignin in the differentiating xylem of magnolia, beech, lilac and poplar. When p-glucocoumaryl alcohol-[arom. ring-2-3H], an efficient precursor of H units in lignin, was administered to the differentiating xylem of these trees, radioactivity was incorporated in the compound middle lamella region of vessel and fiber cell walls. The deposition of H units occurs only in the early stage of cell wall formation when the outer layer of the secondary wall is formed. H lignin deposits mainly within pectic substances and hemicellulose gel to form a highly condensed structural moiety. 相似文献
59.
Tomotsugu Aoyama Yuzuru Takamura Kazuhiko Kuribayashi 《Metallurgical and Materials Transactions A》1999,30(5):1333-1339
The crystal growth behavior of a semiconductor from a very highly undercooled melt is expected to be different from that of
a metal. In the present experiment, highly pure undoped Si and Ge were undercooled by an electromagnetic levitation method,
and their crystal growth velocities (V) were measured as a function of undercooling (ΔT). The value of V increased with ΔT, and V=26 m/s was observed at ΔT=260 K for Si. This result corresponds well with the predicted value based on the dendrite growth theory. The growth behaviors
of Si and Ge were found to be thermally controlled in the measured range of undercooling. The microstructures of samples solidified
from undercooled liquid were investigated, and the amount of dendrites immediately after recalescence increased with undercooling.
The dendrite growth was also observed by a high-speed camera. 相似文献
60.
DNA is a typical organic compound with marked differences from other chemicals and biopolymers because DNA can be amplified by the enzyme polymerase. DNA can be, in principle, amplified from a single copy by the polymerase chain reaction (PCR). In this review, we focus our attention on the chemistry of PCR primers. Because PCR is basic technology in biology research fields, we sometimes use chemically labeled primers without any awareness of the chemistry they leave behind. We would like to emphasize that chemically labeled primers contain a lot of potential for different chemistry ideas and much study is still necessary to advance PCR for single-nucleotide polymorphism (SNP) typing, genetic diagnosis, and other fields. Two categories of primers, affinity-capture primers and signaling primers, are discussed from the viewpoints of their chemical concepts and applications. Affinity-capture primers are used for purification, isolation, and manipulation of PCR products by high specificity and affinity to the cognate molecules by molecule molecule interactions, whereas signaling primers report the hybridization and/or progress of PCR amplification by a signal change, in most cases by a fluorescence change. The content of this review may be useful for a better understanding of the chemistry of PCR primers and, more importantly, for the invention of novel PCR chemistry. 相似文献