全文获取类型
收费全文 | 3201篇 |
免费 | 105篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 166篇 |
综合类 | 6篇 |
化学工业 | 818篇 |
金属工艺 | 87篇 |
机械仪表 | 81篇 |
建筑科学 | 80篇 |
矿业工程 | 1篇 |
能源动力 | 148篇 |
轻工业 | 326篇 |
水利工程 | 13篇 |
石油天然气 | 1篇 |
无线电 | 195篇 |
一般工业技术 | 583篇 |
冶金工业 | 379篇 |
原子能技术 | 133篇 |
自动化技术 | 300篇 |
出版年
2023年 | 23篇 |
2022年 | 45篇 |
2021年 | 84篇 |
2020年 | 25篇 |
2019年 | 40篇 |
2018年 | 88篇 |
2017年 | 64篇 |
2016年 | 115篇 |
2015年 | 56篇 |
2014年 | 104篇 |
2013年 | 195篇 |
2012年 | 154篇 |
2011年 | 203篇 |
2010年 | 142篇 |
2009年 | 169篇 |
2008年 | 182篇 |
2007年 | 130篇 |
2006年 | 120篇 |
2005年 | 127篇 |
2004年 | 103篇 |
2003年 | 94篇 |
2002年 | 101篇 |
2001年 | 69篇 |
2000年 | 51篇 |
1999年 | 67篇 |
1998年 | 165篇 |
1997年 | 103篇 |
1996年 | 59篇 |
1995年 | 43篇 |
1994年 | 45篇 |
1993年 | 53篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 20篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1983年 | 23篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 5篇 |
1972年 | 3篇 |
排序方式: 共有3317条查询结果,搜索用时 15 毫秒
991.
The SIMMER-IV computer code is a three-dimensional fluid-dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron transport kinetics model. The present study has attempted the first application of SIMMER-IV to a core disruptive accident in a large-scale sodium-cooled fast reactor. A principal point of this study was to investigate reactivity effects with fuel relocation under three-dimensional core representation including control rods. The calculation has indicated that the fuel discharge from the core was disturbed by a significant flow resistance at the entrance nozzle in the current design. Additional static neutronic calculations have been performed to compare basic neutronic characteristics between different scale cores. The static neutronic calculations have clarified that the outward fuel compaction within the inner core increased the reactivity in the large-scale core unlike the small-scale core. 相似文献
992.
Hiroo Nakamura Pietro Agostini Kuniaki Ara Satoshi Fukada Kazuyuki Furuya Pascal Garin Alessandro Gessi David Giusti Friedrich Groeschel Hiroshi Horiike Mizuho Ida Takuji Kanenmura Hiroo Kondo Nikolai Loginov Gioacchino Micciche Makoto Miyashita F.S. Nitti Akihiro Suzuki Takayuki Terai Kazuhiro Watanabe A. Mikheyev 《Fusion Engineering and Design》2009,84(2-6):252-258
In International Fusion Materials Irradiation Facility (IFMIF), intense neutron flux (4.5 × 1017 n/m2 s) with a peak energy of 14 MeV are produced by means of two deuteron beams with a total current of 250 mA and maximum energy of 40 MeV that strike a liquid Li target circulating in a Li loop. Major design requirement is to provide a stable Li jet at a speed of 10–20 m/s with a surface wave amplitude on the Li flow less than 1 mm for handling of an averaged heat flux of 1 GW/m2 under a continuous 10 MW deuterium beam deposition. The target system consists of a target assembly, a replaceable back-plate, a Li main loop and a Li purification loop. In July 2007, Engineering Validation and Engineering Design Activities (EVEDA) started under Broader Approach. In this paper, status of the engineering design of the IFMIF Li target system performed in 2007/2008 is described. The future EVEDA tasks to develop the target system are also summarized. 相似文献
993.
Uchimura E Yamada S Nomura T Matsumoto K Fujita S Miyake M Miyake J 《Journal of Bioscience and Bioengineering》2007,104(2):152-155
Reverse transfection from a solid surface has the potential to deliver genes to various cells more efficiently than conventional methods. However, the effective gene delivery from a solid surface requires an optimized extracellular matrix (ECM) for the coating of glass slides, dependent on the nature of the cells. In a search for an appropriate substrate for the universal application to multiple types of cell, we focused on cell surface antigens and examined the effects of antibodies raised against them on gene transfer from an antibody-coated surface. We found that a coating of CD29-specific antibody allowed the most effective delivery of genes by reverse transfection in every type of cell that we examined. Our results suggest that reverse transfection with antibodies against CD29 might provide a universal tool for gene delivery and cell array-based analyses. 相似文献
994.
Increased riboflavin production from activated bleaching earth by a mutant strain of Ashbya gossypii
Satoshi Tajima Yoko Itoh Takashi Sugimoto Tatsuya Kato Enoch Y. Park 《Journal of Bioscience and Bioengineering》2009,108(4):325-329
The production of riboflavin from vegetable oil was increased using a mutant strain of Ashbya gossypii. This mutant was generated by treating the wild-type strain with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Riboflavin production was 10-fold higher in the mutant compared to the wild-type strain. The specific intracellular catalase activity after 3 d of culture was 6-fold higher in the mutant than in the wild-type strain. For the mutant, riboflavin production in the presence of 40 mM hydrogen peroxide was 16% less than that in the absence of hydrogen peroxide, whereas it was 56% less for the wild-type strain. The isocitrate lyase (ICL) activity of the mutant was 0.26 mU/mg of protein during the active riboflavin production phase, which was 2.6-fold higher than the wild-type strain. These data indicate that the mutant utilizes the carbon flux from the TCA cycle to the glyoxylate cycle more efficiently than the wild-type strain, resulting in enhanced riboflavin production. This novel mutant has the potential to be of use for industrial-scale riboflavin production from waste-activated bleaching earth (ABE), thereby transforming a useless material into a valuable bioproduct. 相似文献
995.
Yokoyama M Miwa H Maeda S Wakitani S Takagi M 《Journal of Bioscience and Bioengineering》2008,106(1):46-50
Mesenchymal stem cells (MSCs) should be expanded in vitro while maintaining their multilineage potential before differentiation to one mesenchymal lineage for application to regeneration therapy. The effect of fetal calf serum (FCS) on undesirable differentiation during subcultivations for the expansion was investigated. The expression level of the aggrecan gene, which is a marker of chondrogenic differentiation, gradually and markedly increased during the subcultivations of MSCs with the addition of 10% FCS and without additional cytokines. The percentage of cells positive for CD90 and CD166, which are markers of MSCs, decreased, and the percentage of large polygonal cells and the average cell adhesion area increased during the expansion. There was a marked difference in the increase in the aggrecan expression level between the two expansion cultures employing different FCS lots, although their proliferation rates were almost the same. The decrease in FCS concentration resulted in a higher percentage of CD90(+)CD166(+) cells, a lower percentage of large polygonal cells, and a lower level of aggrecan expression. Consequently, FCS components could stimulate MSC differentiation to chondrocytes and a lower concentration could decrease this differentiation. 相似文献
996.
Hashimoto S Suzuki T Shirota Y Honma M Itabashi Y Chyounan T Kamiyama T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2006,47(2):33-40
Lipophilic toxins associated with diarrhetic shellfish poisoning (DSP) in scallops, Patinopecten yessoensis, collected in Hokkaido, Japan were quantified by liquid chromatography-mass spectrometry (LC/MS). Pectenotoxin-6 (PTX6) and yessotoxin (YTX) were the dominant toxins in the scallops, although the percentages of these toxins were different depending on the production area or the sampling period. The quantitative results obtained for the scallops in LC/MS and in mouse bioassay (MBA) were compared. Fifty of the 55 samples found to be exceeding the local quarantine level (0.025 MU/g whole meat) in Hokkaido by LC/MS were quantified by MBA as being below the quarantine level. It is suggested that this discrepancy is due to poor detection of YTX by MBA. These results indicate that LC/MS is a better method than MBA in terms of sensitivity and accuracy to quantify known lipophilic toxins, including YTX. 相似文献
997.
Effect of Existence of Exogenous Protein on Physicochemical Properties of Heat- and Transglutaminase-induced Bovine Collagen-peptide Gel 总被引:1,自引:0,他引:1
Yuny Erwanto Satoshi Kawahara Kazunori Katayama Abdulatef M. Ahhmed Kiyoshi Yamauchi Koo B. Chin Michio Muguruma 《Journal of food science》2005,70(9):E505-E509
ABSTRACT: The combined influence of preheat treatment, mixing with various proteins, and the addition of microbial transglutaminase (MTGase) on the physicochemical properties of bovine collagen-peptide (BCP) gel was investigated. The preheat treatment and the mixing with various proteins contributed to the enhancement of the gel strength and polymerization of BCP. The gel made with 0.1% MTGase showed the highest breaking strength. The melting point of the preheated BCP gel was higher than that of the unheated one ( P < 0.05). The gel made with a combination of preheated BCP-casein or preheated BCP-soybean protein showed a higher melting point than that made with preheated BCP alone ( P < 0.05). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern of the mixture of preheated BCP with casein or soybean protein showed that the protein bands with relatively low molecular weights disappeared and the bands with relatively high molecular weights increased. Observation by a scanning electron microscope revealed that the preheated BCP gel prepared with MTGase had a well-defined cross-linked network and showed some clumps of aggregated proteins. These results show that preheating, mixing with other proteins and MTGase treatment, are effective ways to make BCP a fine biopolymer. 相似文献
998.
Terada A Hibiya K Nagai J Tsuneda S Hirata A 《Journal of Bioscience and Bioengineering》2003,95(2):170-178
A membrane-aerated biofilm reactor (MABR) capable of simultaneous nitrification and denitrification in a single reactor vessel was developed to investigate the characteristics of nitrogen removal from high-strength nitrogenous wastewater, and biofilm analysis using microelectrodes and the fluorescence in situ hybridization (FISH) technique was performed. Mean removal percentages of total organic carbon (TOC) and nitrogen were 96% and 83% at removal rates of 5.76 g-C m(-2) d(-1) and 4.48 g-N m(-2) d(-1), respectively. For stable removal efficiency, constant washing of the biofilm was needed. Dissolved oxygen microelectrode measurement revealed that the biofilm thickness was about 1600 microm, and that oxygen penetrated about 300 to 700 microm, from the outer surface of the membrane. Furthermore, FISH analysis revealed that ammonia-oxidizing bacteria (AOB) were located near the outer surface of the membrane, whereas other bacteria were located from the inner to the outer part of the biofilm. Combining these results demonstrated that simultaneous nitrification and denitrification occurred in the biofilm of the MABR system. In addition, stoichiometric analysis revealed that after 130 d(-1), the free ammonia (FA) concentration ranged within the concentration causing inhibition of the growth of nitrite oxidizing bacteria (NOB) and that AOB consumed 86% of the oxygen supplied through the intra-membrane. These results indicate that nitrogen removal not via nitrate but via nitrite was mainly achieved in the MABR system. 相似文献
999.
Yomi?Watanabe Yoshie?Yamauchi-Sato Toshihiro?Nagao Satoshi?Negishi Tadamasa?Terai Takashi?Kobayashi Yuji?ShimadaEmail author 《Journal of the American Oil Chemists' Society》2005,82(9):619-623
Production of MAG with CLA using Penicillium camembertii mono- and diacylglycerol lipase (referred to as lipase) was attempted for the purpose of expanding the application of CLA.
The commercial product of CLA (referred to as FFA-CLA) is a FFA mixture containing almost equal amounts of 9cis,11trans (9c,11t)-CLA and 10t,12c-CLA. Esterification of FFA-CLA with glycerol without dehydration achieved 84% esterification but produced almost equal amounts
of MAG and DAG. Esterification with dehydration not only achieved a high degree of esterification but also suppressed the
formation of DAG. When a mixture of FFA-CLA/glycerol (1∶2, mol/mol), 1% water, and 200 units/g-mixture of P. camembertii lipase was agitated at 30°C for 72 h with dehydration at 5 mm Hg, the degree of esterification reached 95% and the contents
of MAG and DAG were 90 and 6 wt%, respectively. This reaction system may be applied to the industrial production of MAG with
unstable CLA. 相似文献
1000.
Satoshi?NegishiEmail author Yuri?Arai Shin?Arimoto Kinya?Tsuchiya Isamu?Takahashi 《Journal of the American Oil Chemists' Society》2003,80(10):971-974
A two-step consecutive synthetic method for the production of symmetrical, structured lipids by a combination of nonselective
and sn-1,3 regioselective ester exchange reactions was investigated. In the first step, TAG with unspecifically substituted DHA
were obtained by reacting tricapryloylglycerol (CCC) with ethyl docosahexanoate (EtDHA) using the lipase QLM (from Alcaligenes sp.), followed by removing the ethyl ester and CCC by molecular distillation. In the second step, sn-1,3 regioselective ester exchange was achieved by reacting the resulting TAG with ethyl caprylate (EtC) using the immobilized
lipase Novozyme 435 (Candida antarctica lipase), followed by distillation of the ethyl ester and CCC to give sn-1,3-dicapryloyl-sn-2-docosahexaenoylglycerol (CDC). The acylglycerol composition of CDC was analyzed by GLC, which showed that the content of
dicapryloyl-docosahexaenoylglycerols (2CD) in the product was 76.4%, and that the ratio of CDC to sn-1,2-dicapryloyl-sn-3-docosahexaenoylglycerol contained in 2CD was 82.7∶17.3 (%). The distillates CCC, EtDHA, and EtC could be recycled repeatedly
to produce CDC as the substrate for the consecutive ester exchange reaction. In addition, separation of CCC and EtDHA was
unnecessary for reuse. The present method is considered to meet the requirements for industrial utilization, in which simplicity
in scaleup, high yields, compact reaction system, and minimal formation of by-products are important factors. 相似文献