全文获取类型
收费全文 | 210篇 |
免费 | 0篇 |
专业分类
系统科学 | 1篇 |
现状及发展 | 83篇 |
研究方法 | 22篇 |
综合类 | 102篇 |
自然研究 | 2篇 |
出版年
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 12篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有210条查询结果,搜索用时 15 毫秒
71.
72.
The magnesium ion Mg2+ is a vital element involved in numerous physiological processes. Mg2+ has the largest hydrated radius among all cations, whereas its ionic radius is the smallest. It remains obscure how Mg2+ transporters selectively recognize and dehydrate the large, fully hydrated Mg2+ cation for transport. Recently the crystal structures of the CorA Mg2+ transporter were reported. The MgtE family of Mg2+ transporters is ubiquitously distributed in all phylogenetic domains, and human homologues have been functionally characterized and suggested to be involved in magnesium homeostasis. However, the MgtE transporters have not been thoroughly characterized. Here we determine the crystal structures of the full-length Thermus thermophilus MgtE at 3.5 A resolution, and of the cytosolic domain in the presence and absence of Mg2+ at 2.3 A and 3.9 A resolutions, respectively. The transporter adopts a homodimeric architecture, consisting of the carboxy-terminal five transmembrane domains and the amino-terminal cytosolic domains, which are composed of the superhelical N domain and tandemly repeated cystathionine-beta-synthase domains. A solvent-accessible pore nearly traverses the transmembrane domains, with one potential Mg2+ bound to the conserved Asp 432 within the pore. The transmembrane (TM)5 helices from both subunits close the pore through interactions with the 'connecting helices', which connect the cystathionine-beta-synthase and transmembrane domains. Four putative Mg2+ ions are bound at the interface between the connecting helices and the other domains, and this may lock the closed conformation of the pore. A structural comparison of the two states of the cytosolic domains showed the Mg2+-dependent movement of the connecting helices, which might reorganize the transmembrane helices to open the pore. These findings suggest a homeostasis mechanism, in which Mg2+ bound between cytosolic domains regulates Mg2+ flux by sensing the intracellular Mg2+ concentration. Whether this presumed regulation controls gating of an ion channel or opening of a secondary active transporter remains to be determined. 相似文献
73.
Takeshi Hirabayashi Susumu Ohtsuka Makoto Urata Ko Tomikawa Hayato Tanaka 《Journal of Natural History》2016,50(27-28):1759-1772
The oceanic calanoid copepod family Heterorhabdidae is unique in that it comprises both particle-feeding and carnivorous genera with some intermediate taxa. Both morphological and molecular (nuclear 18S and 28S rRNA) phylogenetic analyses of the family suggest that an evolutionary switch in feeding strategy, from transitions of typical particle-feeding through some intermediate modes to sophisticated carnivory, might have occurred with the development of a specially designed ‘poison’ injection system. In view of the small amount of genetic differentiation among genera in this family, the switching of feeding modes and re-colonization from deep to shallow waters might have occurred over a short geological period since the Middle to Late Miocene. 相似文献
74.
The subcellular distribution of cholinesterase (ChE) was studied in the gastrocnemius muscle of rats after strong or weak nerve crushing. The ChE activities of muscle were decreased to a greater extent by strong crushing than by weak crushing. In particular, the ChE activity of the fraction containing sarcoplasmic reticulum was most greatly decreased. These results suggest that the change in the ChE activity of the microsomal fraction most finely reflects the strength of nerve crushing. 相似文献
75.
76.
INTRODUCTION
Oil palm, Elaeis Guineensis, (Figure 1) is one of the
most important plants in Malaysia. It produces palm
oil and palm kernel oil, which is widely being used in
food and other industries such as detergents and
cosmetics. Malaysia is the world′s largest producer
and exporter of the oil, so that the country′s economy
is very much dependent on these oil products.
Although oil from the palm tree is an excellent
product for the country, residues from oil palm have
not been used sufficiently. In this 10~15 years,
development in new technologies for utilizing this
lignocellulosic waste is categorized as one of the
most important issues in science policy of Malaysia. 相似文献
77.
78.
79.
M. Yoshida M. Sakai K. Kani I. Nagatsu M. Tanaka 《Cellular and molecular life sciences : CMLS》1988,44(8):700-702
Summary By using an antiserum raised against dopamine bound to bovine serum albumin, thinner dopamine-labeled nerve terminals were visualized immunohistochemically within neocortical areas, in addition to well-documented dopaminergic innervation into the prefrontal and limbic cortices.This study was supported in part by a Grant-in-Aid for Scientific Research on Priority Areas, Japanese Ministry of Education, Science, Culture (No. 62623002). 相似文献
80.
Analysis of a human DNA excision repair gene involved in group A xeroderma pigmentosum and containing a zinc-finger domain 总被引:43,自引:0,他引:43
K Tanaka N Miura I Satokata I Miyamoto M C Yoshida Y Satoh S Kondo A Yasui H Okayama Y Okada 《Nature》1990,348(6296):73-76
Xeroderma pigmentosum (XP) is an autosomal recessive disease, characterized by a high incidence of sunlight-induced skin cancer. Cells from people with this condition are hypersensitive to ultraviolet because of a defect in DNA repair. There are nine genetic complementation groups of XP, groups A-H and a variant. We have cloned the mouse DNA repair gene that complements the defect of group A, the XPAC gene. Here we report molecular cloning of human and mouse XPAC complementary DNAs. Expression of XPAC cDNA confers ultraviolet-resistance on several group A cell lines, but not on lines of other XP groups. Almost all group A lines tested showed abnormality or absence of XPAC messenger RNAs. These results indicate that a defective XPAC gene causes group A XP. The human and mouse XPAC genes are located on chromosome 9q34.1 and chromosome 4C2, respectively. Human XPAC cDNA encodes a protein of 273 amino acids with a zinc-finger motif. 相似文献