全文获取类型
收费全文 | 1919篇 |
免费 | 105篇 |
国内免费 | 1篇 |
出版年
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 24篇 |
2015年 | 44篇 |
2014年 | 51篇 |
2013年 | 158篇 |
2012年 | 90篇 |
2011年 | 88篇 |
2010年 | 45篇 |
2009年 | 49篇 |
2008年 | 78篇 |
2007年 | 95篇 |
2006年 | 92篇 |
2005年 | 75篇 |
2004年 | 72篇 |
2003年 | 79篇 |
2002年 | 67篇 |
2001年 | 57篇 |
2000年 | 79篇 |
1999年 | 70篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 45篇 |
1991年 | 45篇 |
1990年 | 42篇 |
1989年 | 52篇 |
1988年 | 38篇 |
1987年 | 44篇 |
1986年 | 24篇 |
1985年 | 31篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 10篇 |
1979年 | 22篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1971年 | 9篇 |
排序方式: 共有2025条查询结果,搜索用时 890 毫秒
51.
52.
Chloroplast division in Nannochloris bacillaris Naumann (Chlorophyta) was examined by electron microscopy after preparation of samples by freeze-substitution. A pair of belts appeared on the surface of the outer and inner envelope membranes at the middle of the chloroplast. These belts seemed to be constructed of thin fibrils that run parallel to the longitudinal direction of the belts. The outer fibrillar belt increased in width as the constriction of the chloroplast advanced. It appears that the fibrillar belt is the division apparatus of the chloroplast. It encircles the chloroplast and finally divides the chloroplast in two as the diameter of the belt decreases. 相似文献
53.
54.
Q. Wang C.K. Noguchi M. Kuninobu Y. Hara K. Kakimoto H.I. Ogawa Y. Kato 《Biotechnology Techniques》1997,11(2):105-108
Continuous anaerobic digestion of waste activated sludge pretreated at low temperatures below 100°C increased methane generation by 30%. pH values of the digestion mixture increased, approximately from 0.3 to 0.55 by pretreatment, although its volatile fatty acids concentration was greater than the control. An abrupt increase in propionate : acetate ratio in digestion stage (e.g. from less than 1:1 to over 3.5 :1), provided a reliable indicator for impending failure.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
55.
Using a laser confocal microscope, chromatin arrangements in intact interphase nuclei were investigated in four plant species.
Chromosomes in these plants have specific segments that can be stained with the fluorescent dye chromomycin A3 (CMA). We stained centromeres inHordeum vulgare, sub-telomeric regions inSecale cereale, satellites inChrysanthemum multicore, and the satellites and the short arms of chromosomes with satellites inHemerocallis middendorfii. The following points were shown: (1) In mitotic interphase nuclei, the centromere and the telomeres of both arms touched
the nuclear membrane and had evident polarity. Some CMA-bodies in sub-telomeric regions do not contact the nuclear membrane.
(2) Differentiated nuclei had a non-random construction. Polarity of chromosomes is maintained, however, the chromosomes are
far apart from the nuclear membrane. (3) Associations in sub-telomeric regions in the interphase nuclei ofSecale cereale were probably due to the association of heterochromatic regions with identical repeated sequences rather than telomere associlations.
(4) In interphase nuclei ofChrysanthemum multicore, satellites fused during interphase. 相似文献
56.
Cell-free synthesis of ornithine decarboxylase. Changes in mRNA activity in the liver of thioacetamide-treated rats 总被引:1,自引:0,他引:1
T Kameji K Fujita T Noguchi M Takiguchi M Mori M Tatibana S Hayashi 《European journal of biochemistry》1984,144(1):35-39
Ornithine decarboxylase (ODC)mRNA associated with free polysomes of rat liver was translated in a reticulocyte lysate cell-free system. Newly synthesized ODC protein was identified by specific immunoprecipitation, molecular size as determined by polyacrylamide gel electrophoresis with sodium dodecyl sulfate, and competition by excess unlabeled ODC in the immunoprecipitation. A single injection of thioacetamide was found to cause several fold increases in both immunotitratable ODC protein and polysomal ODC-mRNA activity, while it provoked a much larger increase in ODC activity in rat liver. The results indicate that the induction of hepatic ODC activity by thioacetamide treatment is due not only to an increase in the activity of polysomal ODC-mRNA but also to a translational and/or posttranslational control. 相似文献
57.
58.
Structure determination of a nucleoside Q precursor isolated from E. coli tRNA: 7-(aminomethyl)-7-deazaguanosine. 总被引:5,自引:3,他引:2
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
N Okada S Noguchi S Nishimura T Ohgi T Goto P F Crain J A McCloskey 《Nucleic acids research》1978,5(7):2289-2296
A precursor of modified nucleoside Q isolated from E. coli methyl-deficient tRNA was determined to be 7-(aminomethyl)-7-deazaguanosine. The structure was deduced by means of its chromatographic and electrophoretic mobilities, and UV and mass spectra, in addition to comparison with the synthesized authentic compound. The same molecule is also found in tRNA of an E. coli mutant selected for deficient synthesis of modified nucleosides. 相似文献
59.
M Diesterhaft T Noguchi J Hargrove C Thornton D Granner 《Biochemical and biophysical research communications》1977,79(4):1015-1022
Tyrosine aminotransferase messenger RNA has been translated in a cell-free system derived from rabbit reticulocytes. Cytoplasmic poly(A)-containing RNA from rat liver was used as the source of the messenger RNA. The newly synthesized subunits of the enzyme were isolated by immunoprecipitation and identified and quantitated using polyacrylamide gel electrophoresis. These procedures were used to demonstrate that glucocorticoid induction is associated with increased cytoplasmic levels of functional tyrosine aminotransferase messenger RNA. 相似文献
60.
Koshi Saito Hamako Obata-Sasamoto Shin-Ichi Hatanaka Hiroshi Noguchi Ushio Sankawa Atsushi Komamine 《Phytochemistry》1982,21(2):474-476
Isolation and identification of l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline from seeds and callus of S. hassjoo are described. Administration of [β-14C]-labelled DOPA to a callus culture of this legume resulted in the incorporation of radioactivity into l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and stizolobic acid, which was confirmed by constant specific radioactivity after co-crystallization with authentic samples of each compound. 相似文献