全文获取类型
收费全文 | 149篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
系统科学 | 5篇 |
现状及发展 | 69篇 |
研究方法 | 6篇 |
综合类 | 70篇 |
出版年
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1965年 | 1篇 |
1964年 | 4篇 |
1960年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有150条查询结果,搜索用时 31 毫秒
81.
82.
Homogeneous climate variability across East Antarctica over the past three glacial cycles 总被引:1,自引:0,他引:1
Recent ice core studies have raised the disturbing possibility that glacial-interglacial climate changes may be non-uniform across Antarctica. These findings have been confined to records from the Ross Sea sector of the continent, but significant deviations in other areas would call into question the widely assumed validity of the climate record obtained from Vostok, East Antarctica, on large spatial scales. Here we present an isotopic profile from a core drilled at Dome Fuji, situated 1,500 km from Vostok in a different sector of East Antarctica. The two records show remarkable similarities over the past three glacial cycles (the extent of the Dome Fuji record) in both large-amplitude changes, such as terminations, interglacials and interstadials and more subtle glacial events, even when the origin of precipitation is accounted for. Our results indicate that Antarctic climate is essentially homogeneous at the scale of the East Antarctic Plateau, possibly as a consequence of the symmetry of the plateau and the adjacent ocean. 相似文献
83.
Yoshida Y Obita T Kokusho Y Ohmura T Katayama T Ueda T Imoto T 《Cellular and molecular life sciences : CMLS》2003,60(9):1998-2008
DnaA protein binds specifically to a 9-base- pair motif called the DnaA box. Domain IV comprises 94 amino acid residues and is required for DNA binding. Using nuclear magnetic resonance analysis, we investigated the interaction between DnaA domain IV and both a DnaA box and a non-specific oligonucleotide that has a reduced affinity for DnaA. The 1H-15N HSQC spectrum of DnaA domain IV showed prominent chemical shift perturbations on six residues (Arg399, Ala404, Leu422, Asp433, Thr435 and Thr436) in the presence of the DnaA box. Through homology modeling, we located all of these residues on one side surface of the DnaA domain IV molecule. Moreover, we compared the chemical shift perturbation of the 1H-15N HSQC spectrum in the presence of the DnaA box with that in the presence of a non-specific oligonucleotide, and the results suggested that Leu422 imparts specificity in binding with the DnaA box.Received 6 May 2003; received after revision 18 June 2002; accepted 4 July 2003 相似文献
84.
85.
86.
M. Yoshida H. Yokoo H. Kojima K. Suetake S. Anraku K. Inanaga 《Cellular and molecular life sciences : CMLS》1981,37(5):491-492
Summary Sulpiride accelerated the dopamine turnover preferentially in the mesolimbic as compared to the nigrostriatal dopamine system. However, the tuberoinfundibular dopamine turnover was not affected by sulpiride or haloperidol.Acknowledgments. This study was supported in part by a grant No. 4, 1979, from National Center for Nervous, Mental and Muscular Disorder (NCNMD) of the Ministry of Health and Welfare, Japan. We would like to thank Fujisawa pharmaceutical Co., Ltd for the gift of sulpiride. 相似文献
87.
88.
Matsuzaki M Misumi O Shin-I T Maruyama S Takahara M Miyagishima SY Mori T Nishida K Yagisawa F Nishida K Yoshida Y Nishimura Y Nakao S Kobayashi T Momoyama Y Higashiyama T Minoda A Sano M Nomoto H Oishi K Hayashi H Ohta F Nishizaka S Haga S Miura S Morishita T Kabeya Y Terasawa K Suzuki Y Ishii Y Asakawa S Takano H Ohta N Kuroiwa H Tanaka K Shimizu N Sugano S Sato N Nozaki H Ogasawara N Kohara Y Kuroiwa T 《Nature》2004,428(6983):653-657
Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. Here we report the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells. 相似文献
89.
In all nitrogen-fixation processes known so far--including the industrial Haber-Bosch process, biological fixation by nitrogenase enzymes and previously described homogeneous synthetic systems--the direct transformation of the stable, inert dinitrogen molecule (N2) into ammonia (NH3) relies on the powerful redox properties of metals. Here we show that nitrogen fixation can also be achieved by using a non-metallic buckminsterfullerene (C60) molecule, in the form of a water-soluble C60:gamma-cyclodextrin (1:2) complex, and light under nitrogen at atmospheric pressure. This metal-free system efficiently fixes nitrogen under mild conditions by making use of the redox properties of the fullerene derivative. 相似文献
90.
Kinoshita A Saito T Tomita H Makita Y Yoshida K Ghadami M Yamada K Kondo S Ikegawa S Nishimura G Fukushima Y Nakagomi T Saito H Sugimoto T Kamegaya M Hisa K Murray JC Taniguchi N Niikawa N Yoshiura K 《Nature genetics》2000,26(1):19-20
Camurati-Engelmann disease (CED, MIM 131300) is an autosomal dominant, progressive diaphyseal dysplasia characterized by hyperosteosis and sclerosis of the diaphyses of long bones. We recently assigned the CED locus to an interval between D19S422 and D19S606 at chromosome 19q13.1-q13.3, which two other groups confirmed. As the human transforming growth factor-1 gene (TGFB1) is located within this interval, we considered it a candidate gene for CED. 相似文献