全文获取类型
收费全文 | 1531篇 |
免费 | 47篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 87篇 |
综合类 | 6篇 |
化学工业 | 356篇 |
金属工艺 | 27篇 |
机械仪表 | 24篇 |
建筑科学 | 29篇 |
能源动力 | 60篇 |
轻工业 | 120篇 |
水利工程 | 5篇 |
石油天然气 | 6篇 |
无线电 | 142篇 |
一般工业技术 | 262篇 |
冶金工业 | 274篇 |
原子能技术 | 54篇 |
自动化技术 | 130篇 |
出版年
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 24篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 54篇 |
2012年 | 58篇 |
2011年 | 63篇 |
2010年 | 71篇 |
2009年 | 73篇 |
2008年 | 71篇 |
2007年 | 55篇 |
2006年 | 41篇 |
2005年 | 47篇 |
2004年 | 45篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 39篇 |
2000年 | 30篇 |
1999年 | 32篇 |
1998年 | 104篇 |
1997年 | 73篇 |
1996年 | 51篇 |
1995年 | 48篇 |
1994年 | 42篇 |
1993年 | 31篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 8篇 |
排序方式: 共有1582条查询结果,搜索用时 31 毫秒
121.
Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation 下载免费PDF全文
Dr. Atsuko Uyeda Dr. Takayoshi Watanabe Dr. Yasuhiko Kato Prof. Hajime Watanabe Prof. Tetsuya Yomo Prof. Takahiro Hohsaka Dr. Tomoaki Matsuura 《Chembiochem : a European journal of chemical biology》2015,16(12):1797-1802
Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation. 相似文献
122.
[This corrects the article on p. 1930 in vol. 11, PMID: 20480050.]. 相似文献
123.
Kubota K Kasuga F Iwasaki E Inagaki S Sakurai Y Komatsu M Toyofuku H Angulo FJ Scallan E Morikawa K 《Journal of food protection》2011,74(10):1592-1598
Most cases of acute gastroenteritis and foodborne disease are not ascertained by public health surveillance because the ill person does not always seek medical care and submit a stool sample for testing, and the laboratory does not always test for or identify the causative organism. We estimated the total burden of acute gastroenteritis in Miyagi Prefecture, Japan, using data from two 2-week cross-sectional, population-based telephone surveys conducted in 2006 and 2007. To estimate the number of acute gastroenteritis illnesses caused by Campylobacter, Salmonella, and Vibrio parahaemolyticus in Miyagi Prefecture, we determined the number of cases for each pathogen from active laboratory-based surveillance during 2005 to 2006 and adjusted for seeking of medical care and submission of stool specimens by using data from the population-based telephone surveys. Monte Carlo simulation was used to incorporate uncertainty. The prevalence of acute gastroenteritis in the preceding 4 weeks was 3.3% (70 of 2,126) and 3.5% (74 of 2,121) in the winter and summer months, yielding an estimated 44,200 episodes of acute gastroenteritis each year in this region. Among people with acute gastroenteritis, the physician consultation rate was 32.0%, and 10.9% of persons who sought care submitted a stool sample. The estimated numbers of Campylobacter-, Salmonella-, and V. parahaemolyticus -associated episodes of acute gastroenteritis were 1,512, 209, and 100 per 100,000 population per year, respectively, in this region. These estimates are significantly higher than the number of reported cases in surveillance in this region. Cases ascertained from active surveillance were also underrepresented in the present passive surveillance, suggesting that complementary surveillance systems, such as laboratory-based active surveillance in sentinel sites, are needed to monitor food safety in Japan. 相似文献
124.
Kunihisa Iwai Akio Onodera Hajime Matsue 《Journal of the science of food and agriculture》2003,83(15):1593-1599
The fruit of Viburnum dilatatum Thunb (gamazumi) has been shown to prevent oxidative injury induced by water immersion restraint stress (WIRS) in rats. In this study the effect of gamazumi crude extract (GCE) on antioxidant enzymatic activities in the plasma, liver and stomach of rats with WIRS was investigated to elucidate the mechanism of prevention of oxidative injury. Ulcer formation and lipid peroxidation were inhibited in rats supplied GCE for 2 weeks in comparison with rats supplied water. Although the activities of plasma, hepatic and gastric antioxidant enzymes in rats given water were decreased by WIRS, only slight changes were observed in rats given GCE. There was no difference in enzymatic activities between the water and GCE groups not subjected to WIRS. Furthermore, ferrous ascorbate‐induced oxidation in hepatic homogenate from rats given GCE was inhibited. These results suggest that ingestion of GCE does not induce antioxidant enzymes and that the absorbed antioxidant components of GCE have a direct effect on oxidative injury in the body. Copyright © 2003 Society of Chemical Industry 相似文献
125.
M Utsumi K Moriguchi H Takahashi C Kinoshita A Togari M Mizutani N Ohno 《Journal of electron microscopy》1999,48(2):139-145
The ultrastructure of the parathyroid gland (PTG) of the UM-X7.1 cardiomyopathic hamster (the UM-X7.1) was qualitatively and quantitatively compared with that of the normal hamster. In the UM-X7.1, the Golgi apparatus and rER were well developed compared with those of the control hamster. Morphometric analysis revealed that the mean values of the Golgi apparatus, rER and large vacuolar bodies were significantly greater in the UM-X7.1 than in the normal hamster and the mean value of lipid droplets was significantly less in the UM-X7.1 than in the normal hamster. Ultrastructurally, we consider that in the UM-X7.1, the synthesis and release of the parathyroid hormone may be activated by an excessive amount of circulating catecholamine, and the functional activity of the PTG may be higher than that in the normal hamster. 相似文献
126.
127.
Hajime Araki Taichi Kaji Masahito Yamamoto Keiji Suzuki Azuma Ohuchi 《Electrical Engineering in Japan》2001,135(4):43-51
The optimal sequential problem is defined as the problem of finding the minimum cost partition of the nodes of a directed acyclic graph into subsets of a given size, subject to the constraint that the precedence relationships among the elements are satisfied. A heuristic algorithm based on tabu search has been proposed for this problem [2]. However, there is a tendency for the solutions obtained by tabu search to become trapped in bad local optima in parallel graphs with random edge costs. In this paper we present a genetic algorithm for the optimal sequential partitioning problem. We develop an effective two‐point partial order crossover satisfying sequential conditions, which preserve better blocks that have a larger sum of edge costs. In this crossover we introduce the roulette selection method to escape local optima. We also assess the effectiveness of the algorithm. The results show that this proposed algorithm outperforms any other algorithm using tabu search in terms of solution quality. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 43–51, 2001 相似文献
128.
Hajime Yano Daigo Kouro Naoki Sasaki Shin-ichi Muramatsu 《Solar Energy Materials & Solar Cells》2009,93(6-7):976-979
We have found that the short-circuit current, Jsc, of polymer/fullerene [RR-P3HT/C60] solar cells has a clear dependence on the surface roughness of the ITO/glass substrate. We prepared an ITO surface with an average roughness, Ra, of 0.7–11 nm by chemical etching. At first Jsc increases with the increase in ITO surface roughness and then gradually decreases. The maximum performance was obtained at Ra≈4 nm. Jsc is also high with a very flat surface of Ra=0.7 nm. This feature can be attributed to the trade-off between the increase in absorption light path length and film-quality deterioration. 相似文献
129.
130.
Shiro Seki Takeshi Kobayashi Nobuyuki Serizawa Yo Kobayashi Katsuhito Takei Hajime Miyashiro Kikuko Hayamizu Seiji Tsuzuki Takushi Mitsugi Yasuhiro Umebayashi Masayoshi Watanabe 《Journal of power sources》2010,195(18):6207-6211
The physicochemical and electrochemical properties of three 1-alkyl-2,3,5-trimethylpyrazolium cation-based room-temperature ionic liquids with various alkyl chain lengths were investigated. The temperature dependences of density, viscosity, and ionic conductivity were obtained by precise measurements. Electrolyte properties of these room-temperature ionic liquids were also examined from the viewpoint of their uses in lithium secondary batteries ([LiCoO2 positive electrode|electrolyte|lithium metal negative electrode]). It was found that the alkyl chain length affects the charge–discharge performances of cells. 相似文献