全文获取类型
收费全文 | 1267篇 |
免费 | 32篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 84篇 |
综合类 | 2篇 |
化学工业 | 327篇 |
金属工艺 | 37篇 |
机械仪表 | 31篇 |
建筑科学 | 33篇 |
能源动力 | 84篇 |
轻工业 | 107篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 95篇 |
一般工业技术 | 238篇 |
冶金工业 | 113篇 |
原子能技术 | 53篇 |
自动化技术 | 94篇 |
出版年
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 34篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 19篇 |
2016年 | 34篇 |
2015年 | 24篇 |
2014年 | 45篇 |
2013年 | 87篇 |
2012年 | 63篇 |
2011年 | 82篇 |
2010年 | 55篇 |
2009年 | 53篇 |
2008年 | 65篇 |
2007年 | 62篇 |
2006年 | 62篇 |
2005年 | 40篇 |
2004年 | 44篇 |
2003年 | 35篇 |
2002年 | 23篇 |
2001年 | 21篇 |
2000年 | 24篇 |
1999年 | 26篇 |
1998年 | 43篇 |
1997年 | 34篇 |
1996年 | 21篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1973年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有1303条查询结果,搜索用时 15 毫秒
31.
Yang Liu Sei-Ichi Saitoh Hiromichi Igarashi Toru Hirawake 《International journal of remote sensing》2014,35(11-12):4422-4440
Climate changes affect coastal environments and aquaculture, threatening food security and economic growth. Japanese scallop (Mizuhopecten yessoensis) culture is economically important for the coastal communities of Dalian, China, and Funka Bay, Japan. In this study, we combined satellite remote-sensing data, in situ observations, and a suitable aquaculture site selection model to explore the interactions between marine environments and climate variability over a recent 10-year period (2003–2012). Our selection of appropriate zones in these two Far Eastern regions and our analyses of climatic event (Arctic Oscillation (AO), winter East Asian monsoon (EAM), and El Niño/La Niña Southern Oscillation (ENSO)) and meteorological (precipitation, temperature, and wind) data allowed us to determine the impacts of climate change on regional coastal environments and prospects for scallop aquaculture. These analyses showed that AO and EAM strongly influenced the aquaculture areas on the Dalian coast through their effects on temperature during winter. We also determined that wind was the main driving force behind regional environmental changes during spring. Conversely, ocean conditions and suitable areas in Funka Bay changed rapidly relative to oceanic and atmospheric circulation. In Funka Bay, areas appropriate for scallop aquaculture and variations in chlorophyll-a concentration (which reflect the availability of algal food for scallops) were strongly correlated with ENSO, precipitation, and air temperature. These correlations demonstrate the influence of oceanic and atmospheric parameters on the productivity of scallop aquaculture in Funka Bay. Adaptation to oceanic and atmospheric changes should be considered when developing plans and management strategies for coastal scallop aquaculture in northeast Asia. 相似文献
32.
The single-pass (50 cm) amplifier performance of an atmospheric-pressure ArF laser pumped by a 65-ns full-width-at-half-maximum short-pulse electron beam was investigated theoretically for a wide range of excitation rates (0.1-2.0 MW/cm3 ). Atmospheric mixtures of Ne, Ar, and F2 (three mixtures of Ar=40%, 70%, and Ne-free) were studied. A kinetic numerical model of the ArF amplifier with a Ne buffer system was constructed. A one-dimensional propagation treatment considered the gain depletion and saturation absorption spatially and temporally along the optical axis. In this model the rate constants for electron quenching of ArF* of 1.6×10-7, 1.9×10-7, and 2.4×10 -7 cm3/s were used for Ar concentration of 40, 70 percent, and Ar/F2 mixture, respectively 相似文献
33.
Masahiro Ishida Toru Nakura Takashi Kusaka Satoshi Komatsu Kunihiro Asada 《Journal of Electronic Testing》2016,32(3):257-271
This paper proposes a power integrity control technique for dynamically controlling power supply voltage fluctuations for a device under test (DUT), and demonstrates its effectiveness for eliminating the overkills/underkills due to the difference of power supply impedance between an automatic test equipment (ATE) and a practical operating environment of the DUT. The proposed method injects compensation currents into the power supply nodes on the ATE system in a feed-forward manner such that the ATE power supply waveform matches with the one on the customer’s operating environment of the DUT. A method for calculating the compensation current is also described. Experimental results show that the proposed method can emulate the power supply voltage waveform under a customer’s operating condition and eliminate 95 % of overkills/underkills in the maximum operating frequency testing with 105 real silicon devices. Limitations and applications of the proposed method are also discussed. 相似文献
34.
35.
36.
Dr. Masanobu Nagano Takumi Oguro Ryo Sawada Dr. Toru Yoshitomi Prof. Keitaro Yoshimoto 《Chembiochem : a European journal of chemical biology》2021,22(23):3341-3347
Dysregulation of tumor necrosis factor-α (TNFα), a pro-inflammatory cytokine, causes several diseases, making it an important therapeutic target. Here, we identified a novel DNA aptamer against human TNFα using in vitro selection, which included a high exclusion pressure process against non-binding and weak binders through microbead-assisted capillary electrophoresis (MACE) in only three rounds. Among the 15 most enriched aptamers, Apt14 exhibited the highest inhibitory activity for the interaction between TNFα and its cognate receptor in mouse L929 cells. For further improving the bioactivity of the aptamer, dimerization programed by hybridization was evaluated, resulting in the Apt14 dimer exhibited a twofold higher binding affinity and stronger inhibition compared to the monomer counterpart. Rapid identification of bioactive aptamers using MACE in combination with facile dimerization by hybridization accelerates the discovery of novel bioactive aptamers, paving the way toward replacing current monoclonal antibody therapy with the less expensive and non-immunogenic aptamer therapy. 相似文献
37.
Hidemine Obara Masamu Kamaga Takumi Ito Yukihiko Sato 《Electrical Engineering in Japan》2014,186(4):81-91
Multilevel converters can essentially reduce harmonics even when their switching frequency is low. Among the various topologies of the multilevel converters, flying capacitor converters are considered to be promising converters for realizing high power density. However, the main circuit of the flying capacitor converters has many capacitors. Therefore, in this study, the volume of the capacitors in the flying capacitor converters is determined by taking into consideration the allowable ripple voltage and temperature rise in the capacitor. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(4): 81–91, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22361 相似文献
38.
To develop a simple and effective process for upgrading low-grade titanium ore (ilmenite, mainly FeTiO3), a new selective chlorination process based on the use of calcium chloride (CaCl2) as the chlorine source was investigated in this study. Titanium ore and a titanium ore/CaCl2 mixture were placed in two separate crucibles inside a gas-tight quartz tube that was then positioned in a horizontal furnace. In the experiments, the titanium ore in the two crucibles reacted with either HCl produced from CaCl2 or CaCl2 itself at 1100 K (827 °C), leading to the selective removal of the iron present in the titanium ore as iron chlorides [FeCl x (l,g) (x = 2, 3)]. Various kinds of titanium ores produced in different countries were used as feedstock, and the influence of the particle size and atmosphere on the selective chlorination was investigated. Under certain conditions, titanium dioxide (TiO2) with purity of about 97 pct was directly obtained in a single step from titanium ore containing 51 pct TiO2. Thus, selective chlorination is a feasible method for producing high purity titanium dioxide from low-grade titanium ore. 相似文献
39.
Haruto Kumura Megumi Satoh Taiki Machiya Makoto Hosono Toru Hayakawa Jun‐ichi Wakamatsu 《International Journal of Dairy Technology》2019,72(3):403-408
The lipolytic and proteolytic activity of Penicillium camemberti PC TT033 and Penicillium roqueforti PR G3, cultured on the whey solids or simulated cheese media, were compared under several pH reaction conditions. Lipolytic activity was higher when both strains had been cultured on the whey medium than on the simulated cheese medium, whereas proteolytic activity was less influenced by the culture medium. The relationship between the reaction pH and these enzyme activities was dependent on the culture medium, which suggested that the expression level and balance of isozyme rely on the culture substrate. 相似文献
40.
Toru Moriyama Jun-ichi Mashiko Toshinori Matsui Koichiro Enomoto Tetsuya Matsui Kojiro Iizuka Masashi Toda Yukio Pegio Gunji 《Artificial Life and Robotics》2016,21(3):247-252
The soldier crab appears in great numbers and feeds while wandering during daytime low tide. When they see an approaching object, they screw themselves into the sand. The mechanism of formation of mass wandering has not been clarified. In this study, to investigate if the soldier crabs use visual images of neighbors as a stimulus for wandering, dummy crabs were presented to crabs. In the experiments, one, two, four, or eight dummies were placed in a circle on a sand arena. Each crab was placed in the center of the arena and observed whether it burrowed into the sand or wandered. The proportions of wandering individuals in each experimental treatment were compared with the expected value. Significantly more crabs were wanderers when only two and four dummies were present. This result suggests that soldier crabs chose burrowing or wandering depending on visual image of the distribution of the neighbors. 相似文献