全文获取类型
收费全文 | 586篇 |
免费 | 35篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 11篇 |
2013年 | 29篇 |
2012年 | 44篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 43篇 |
2007年 | 33篇 |
2006年 | 28篇 |
2005年 | 33篇 |
2004年 | 43篇 |
2003年 | 26篇 |
2002年 | 29篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 11篇 |
1997年 | 16篇 |
1996年 | 16篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有621条查询结果,搜索用时 46 毫秒
1.
Extraction and quantitation of astaxanthin from Phaffia rhodozyma 总被引:32,自引:0,他引:32
Summary The rapid, quantitative release of astaxanthin and other carotenoids from the yeast Phaffia
rhodozyma is described. Hashed cells are ruptured with dimethylsulfoxide (DMSO) and carotenoids extracted into an organic solvent. Extraction and spectrophotometric quantitation of total carotenoids is rapid, reproducible and only small volumes (0.1–2 ml) of culture are required. HPLC analysis in normal phase silica gel column indicates that astaxanthin comprises 65–95% of the total pigmented carotenoids of P.
rhodozyma. 相似文献
2.
The use of four stereoisomers of isoleucine by Lactobacillus fermenti strain 36 was studied in detail. All four isoleucine isomers were used for growth in the presence of vitamin B(6) compounds, but only l-isoleucine was active in the absence of these vitamins. Of the vitamin B(6) compounds, pyridoxal and pyridoxamine were equally more effective than pyridoxine for the utilization of these isomers. Lowering the initial pH, decreasing the amounts of leucine and valine, and adapting the organism to d-alloisoleucine medium accelerated the use of isoleucine isomers. Thus, the conditions were established under which respective isomers gave the same growth response, and these findings were applied to the separate microbiological assay of l-isoleucine and total isoleucine isomers. 相似文献
3.
4.
5.
Takeshi Minami Masayo Ichii Yoshiyuki Tohno Setsuko Tohno Masako Utsumi Masa-oki Yamada Yuko Okazaki 《Biological trace element research》1996,55(1-2):199-205
The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries.
The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma
atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45–99-yr-old; 15 of the subjects were males and 8
were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens
where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found.
When related to age, two groups were established. Group L (45–75 yr old) and group H (>75 yr old), which exhibited aortal
Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia,
Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P)
levels (r=0.801,p<0.01) and between Al and calcium (Ca) (r=0.661,p<0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery.
In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation. 相似文献
6.
Phosphorylation of a Protein (pp56) is Related to the Regeneration of Rice Cultured Suspension Cells 总被引:3,自引:0,他引:3
Short-term cultured suspension cells of rice (Oryza sativa L.)are capable of regeneration, but not in long-term culture. Forclarification of the mechanism of regeneration, protein phosphorylationin short-term and long-term cultured suspension cells was comparedby two dimensional- polyacrylamide gel electrophoresis. A 56kDa protein having an isoelectric point of 4.5 was phosphorylatedin vitro in short-term cultured suspension cells, but was notphosphorylated after regeneration. This protein in longtermcultured suspension cells remained phosphorylated after transferto the regeneration medium. However, using an antibody raisedagainst this protein from short-term cultured suspension cells,it was always detected in long-term and short-term culturedsuspension cells after transfer to the regeneration medium.The partial amino acid sequence of the HPLC-purified proteinshowed homology to a calcium-binding protein from maize. Thephosphorylation of the 56 kDa protein (pp56) appears to be associatedwith the regeneration of cultured rice cells. (Received December 11, 1995; Accepted June 3, 1996) 相似文献
7.
Takeshi Nishimura Setsuko Yamamoto Takaaki Yamamoto Munekiyo Kaneko Youichi Hara 《Prostaglandins & other lipid mediators》1996,51(2):149-159
The antithrombotic effect of topical application of the 3-oxamethano-prostaglandin (PG) I1 analog, SM-10902 in the microcirculation and in vitro antiplatelet functions of its active form SM-10906 were estimated in comparison with PGI2 and PGE1. In rat platelets, SM-10906 evoked accumulation of intracellular cyclic adenosine 3′,5′-monophosphate, and exhibited antiaggregatory and disaggregatory activities, which were all enhanced by the phosphodiesterase inhibitor theophylline. Additionally, SM-10906 was shown to inhibit platelet adhesion to collagen in human platelet-rich plasma. PGI2 and PGE1 also showed in vitro antiplatelet effects in the order of PGI2 > SM-10906 ≥ PGE1. SM-10902 exhibited a dose-dependent antithrombotic effect in the guinea pig mesenteric arteriole by a topical application, and this activity might be exerted by the antiplatelet functions of SM-10906. Although SM-10906, PGI2 and PGE1 also showed the antithrombotic effects, SM-10902 was the most potent. In conclusion, the present studies indicate that an external topical preparation of SM-10902 may be useful for the therapy of peripheral circulatory insufficiency. 相似文献
8.
A temperature-sensitive (ts) mutant of the influenza virus A/WSN/ 33 strain, ts-134, possessed a defect in intracellular transport at the nonpermissive temperature and marked thermolability of hemagglutinin (HA) activity at 51 C. These were caused by a change at amino acid residue 157 from tyrosine to histidine in the HA protein. We isolated 37 spontaneous revertant clones from ts-134 at the nonpermissive temperature and determined their HA sequences. The deduced amino acid sequences demonstrated that one was a true revertant and the others were revertants with suppressor mutations, each of which had an additional amino acid change besides those of ts-134. The changed amino acids were located at 14 positions on the HA molecule, and eight of them were found in multiple revertants. These were located in five to six distinct regions on the three-dimensional structure of the HA molecule. However, the heat stability of HAs in the revertants was recovered differently depending on the sites of the changed amino acids. The kinetics of transport of the HA protein in the revertants were slightly delayed compared to the wild-type both at permissive and nonpermissive temperatures. 相似文献
9.
10.
cis-5-Hydroxy-L-pipecolic acid was isolated and characterized from the leaves of Morus alba and the seeds of Lathyrus japonicus. The trans-form was also obtained from the former. 相似文献