全文获取类型
收费全文 | 708篇 |
免费 | 35篇 |
学科分类
工业技术 | 743篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 25篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 18篇 |
2017年 | 8篇 |
2016年 | 20篇 |
2015年 | 14篇 |
2014年 | 30篇 |
2013年 | 44篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 31篇 |
2009年 | 25篇 |
2008年 | 36篇 |
2007年 | 32篇 |
2006年 | 36篇 |
2005年 | 21篇 |
2004年 | 16篇 |
2003年 | 23篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 13篇 |
1998年 | 34篇 |
1997年 | 28篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有743条查询结果,搜索用时 437 毫秒
1.
Atsushi Narumi Kosei Kawasaki Harumi Kaga Toshifumi Satoh Naoya Sugimoto Toyoji Kakuchi 《Polymer Bulletin》2003,49(6):405-410
Summary
The potato phosphorylase-catalyzed polymerization of α-D-glucose-1-phosphate (G-1-P) onto poly[styrene-block-(4-vinylbenzyl maltohexaoside)] (1) was performed at the molar ratios of [G-l-P]0 and [maltohexaose]0 of 35, 80, and 250. The product was found to be soluble in dimethyl sulfoxide, which was a good solvent for amylose, and
showed the complex-formation with iodine, indicating that the product was assignable to poly[styrene-block-(styrene-graft-amylose)] (2). The quantitative analysis of the liberated phosphoric acid gave the average degree of polymerization o f the glucose unit
(n) as 27, 5 1, and 180 for 2-I, 2-II, and 2-III, respectively.
Received: 29 November 2002/Accepted: 22 December 2002
Correspondence to Toyoji Kakuchi 相似文献
2.
Shoji Eguchi 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(5):977-987
Recent progress of synthesis of C60 derivatives functionalized with hetero-cycles is reviewed, focusing attention on [4+2]- and [3+2] cycloaddition methodologies and oxidative heterocyclization. 相似文献
3.
In vitro transdifferentiation of retinal pigmented epithelial cells of the chick embryo into lens cells can be markedly enhanced by culture in the presence of testicular hyaluronidase and phenylthiourea. Since the commercial preparations of hyaluronidase that had previously been used were very crude, a search for the actual effective molecule(s) enhancing lens transdifferentiation was conducted. First, we purified the enzyme and tested the effect of the purified hyaluronidase. Highly purified hyaluronidase itself did not enhance lens transdifferentiation. The crude hyaluronidase was then separated according to affinity with heparin, considering the possibility that the fibroblast growth factor (FGF) is contained in the crude hyaluronidase. Transdifferentiation-enhancing activity was detected in the fraction which was bound to heparin and eluted with 2 M NaCl, where no hyaluronate-degrading activity existed. Analysis of the fraction by SDS-PAGE revealed the existence of an 18 kDa protein whose NH2-terminal sequence was identical to that of basic FGF. The basic FGF derived from bovine brain also enhanced lens transdifferentiation of pigmented epithelial cells. These findings suggest that basic FGF must play a major role in enhancing transdifferentiation of pigmented epithelial cells to lens cells. 相似文献
4.
5.
We studied the role of cytokines and immune regulation in thyroid tissue from patients with Graves' disease. Immunohistochemistry showed that the thyroid glands are characterized by an aberrant expression of HLA class II antigens on thyrocytes, generation of new blood vessels and infiltration of mononuclear cells. We demonstrated that CD4+ memory cells were more frequent in thyroid glands from Graves' patients than were CD4+ naive cells. The intrathyroidal T cells demonstrated an enhanced expression of the adhesion molecules LFA-1, CD2, VLA-4 and VLA-5, and vascular endothelial cells of capillaries and thyrocytes in thyroid glands reacted with anti-ICAM-1 monoclonal antibody. The adhesion molecules and HLA antigens on both vascular endothelial cells and thyrocytes were regulated by inflammatory cytokines. These results suggest that circulating lymphocytes migrate into thyroid tissues and that memory T cells are retained in the thyroid tissues by cellular interactions with thyrocytes or with extracellular matrix. 相似文献
6.
7.
The esters of dichloropropanols from the byproduct of hydrolysates during food processing were degraded by the cell-free extracts of a dichloropropanol-assimilating bacterium of Pseudomonas sp. OS-K-29. 1-Acyloxy-2,3-dichloropropane was hydrolysed into the corresponding carbonic acid and 2,3-dichloropropanol, and then the dichloropropanol was dechlorinated. The esterase activity of the cell-free extracts was effective for the esters of the dichloropropanols and monoacylglycerides, but not for hydrolysing the lipase substrates such as triacylglycerides and Tween 60. A comparative study using a series of octanoyl glycerides and the esters of the dichlopropanols showed that the substrate specificities of the cell-free extracts were similar to the monoacylglyceride lipase from Penicillium camembertii. 相似文献
8.
Ten-user truly asynchronous gigabit OCDMA transmission experiment with a 511-chip SSFBG en/decoder 总被引:8,自引:0,他引:8
Hamanaka T. Xu Wang Naoya Wada Nishiki A. Kitayama K. 《Lightwave Technology, Journal of》2006,24(1):95-102
A ten-user truly asynchronous gigabit coherent-optical-code-division-multiple-access (OCDMA) transmission was experimentally demonstrated without using any timing coordination. The enabling technologies are a record-length 511-chip superstructured-fiber-Bragg-grating (SSFBG) en/decoder and a supercontinuum (SC)-based optical-thresholding technique to significantly suppress the signal interference beat noise as well as the multiple-access-interference (MAI) noise. 相似文献
9.
Takanori Inoue Keiichiro Hoashi Koichi Eguchi Hiromichi Arai 《Journal of Materials Science》1993,28(6):1532-1536
The electrode characteristics of perovskite-type oxides, La0.6Sr0.4CoO3 and La0.6Sr0.4MnO3, on ceria-based oxide and stabilized zirconia were analysed by the a.c. impedance method. The ionic conductivities of the electrolyte and electrode conductivities from the a.c. impedance analysis agreed with those obtained from the current interruption and d.c. four-probe methods. Two semicircles from the charge transfer and diffusion processes appeared as the electrode resistance. The relative contribution of these two processes to the overall electrode resistance strongly depended on the microstructure of the electrode. The electrode microstructure could be controlled by the dispersion medium used for the electrode slurry. The La0.6Sr0.4MnO3 electrode coated with n-butyl acetate slurry exhibited the smallest electrode resistance. 相似文献
10.