全文获取类型
收费全文 | 1463篇 |
免费 | 115篇 |
专业分类
1578篇 |
出版年
2021年 | 15篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 16篇 |
2016年 | 29篇 |
2015年 | 45篇 |
2014年 | 37篇 |
2013年 | 61篇 |
2012年 | 71篇 |
2011年 | 63篇 |
2010年 | 43篇 |
2009年 | 50篇 |
2008年 | 60篇 |
2007年 | 87篇 |
2006年 | 80篇 |
2005年 | 75篇 |
2004年 | 80篇 |
2003年 | 57篇 |
2002年 | 49篇 |
2001年 | 31篇 |
2000年 | 48篇 |
1999年 | 42篇 |
1998年 | 17篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 27篇 |
1991年 | 31篇 |
1990年 | 35篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 29篇 |
1986年 | 24篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1979年 | 23篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1975年 | 9篇 |
1974年 | 14篇 |
1973年 | 11篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1970年 | 13篇 |
1968年 | 6篇 |
排序方式: 共有1578条查询结果,搜索用时 15 毫秒
31.
Hideyo Suzuki Kuo-Hsiung Lee Mitsumasa Haruna Toshiyuki Iida Kazuo Ito Huan-Chang Huang 《Phytochemistry》1982,21(7):1824-1825
A new lignan, (+)-aretigenin has been isolated from the roots of Wikstroemia indica (Nan-Ling-Jao-Hua) and identified as 8(R) 8′(S)-4′-hydroxy-3, 4,3′-trimethoxylignan-olid (9, 9′) on the basis of spectral evidence as well as a direct comparison with its enantiomer, (?)-arctigenin. 相似文献
32.
Summary Comparative restriction cleavage analysis of the genomes of bacteriophage P7, of several recombinant phages between P7 and P1, and of bacteriophage P1 allowed to draw PstI, BglII, BamHI and HindIII cleavage maps of all genomes studied. The data obtained complement Yun and Vapnek's (1977) conclusions with regard to areas of major nonhomology based on electron microscopical heteroduplex analysis and they identify several additional minor differences between P1 and P7. The use of hybrid phage strains allowed to locate the genes for particular functions on the physical genome map.Abbreviations Cm
chloramphenicol
- Ap
ampicillin
- bp
base pairs
- kb
kilo-base pairs 相似文献
33.
Jean T. Walker Shigeru Iida Donald H. Walker Jr. 《Molecular & general genetics : MGG》1979,167(3):341-344
Summary Use of restriction endonucleases BglII, EcoRI, BamHI, and HindIII, has established that in small-headed (PIS) virions of coliphage P1, as a population, the entire genome found in big-headed (P1B) virions is represented. In addition, the origin and direction of DNA packaging are identical in P1S and P1B virions. 相似文献
34.
In order to clarify individual differences in bone metabolism among colony-raised beagle dogs, histomorphometric values of iliac trabecular bone and values of serum biochemical constituents related to bone were examined in 10 and 17 beagle dogs raised, respectively, under our two breeding systems in which differences in factors such as exercise, ultraviolet rays, and mineral content of the diet affect bone metabolism. At the age of 14 months, all dogs were injected with tetracycline hydrochloride and calcein twice for double bone labeling in order to measure dynamic as well as static parameters by bone histomorphometry and the ilium was later biopsied. The measurement on cancellous bone areas of undecalcified iliac sections was performed with a semiautomatic image analyser. Values of total calcium, phosphorus, alkalinephosphatase activity, parathyroid hormone and calcitonin in serum were also determined. The results showed that there were no significant differences between the two groups in histomorphometric values, except for the osteoid volume (p less than 0.05) and osteoid surface/trabecular surface ratio (p less than 0.01) in females, or in serum biochemical constituents, except for alkalinephosphatase activity (p less than 0.001) in males, indicating there were virtually no individual differences in bone metabolism in normal colony raised beagle dogs. 相似文献
35.
Plant transposable elements and gene tagging] 总被引:1,自引:0,他引:1
36.
A DBL-homologous region of the yeast CLS4/CDC24 gene product is important for Ca(2+)-modulated bud assembly. 总被引:7,自引:0,他引:7
S Miyamoto Y Ohya Y Sano S Sakaguchi H Iida Y Anraku 《Biochemical and biophysical research communications》1991,181(2):604-610
The CLS4/CDC24 is essential for the budding process of the yeast Saccharomyces cerevisiae. Disruption of the CLS4/CDC24 gene is lethal, and expression of the CLS4 product under the control of the GAL1 promoter is sufficient for cellular growth. The CLS4 product is detected in yeast cell lysate with an apparent molecular mass of 93 kD (854 amino acid residues) and shows homology with the human DBL oncogene product. Temperature-sensitive cdc24-1 mutation is located in the N-terminal portion of the protein whereas Ca(2+)-sensitive cls4-1 mutation is present after the DBL-homologous region (amino acid residues 281-518) near the putative Ca(2+)-binding site. Mutations within the DBL-homologous region are responsible for the Ca(2+)-sensitive phenotype. Thus the CLS4 gene product seems to have several functional domains within the molecule essential for bud assembly. 相似文献
37.
38.
Y Hirabayashi Y Matsumoto M Matsumoto T Toida N Iida T Matsubara T Kanzaki M Yokota I Ishizuka 《The Journal of biological chemistry》1990,265(3):1693-1701
Four major sialo compounds, termed GP-M1, GP-D1, GP-D2, and GP-D3 have been isolated from the urine of a novel glycoprotein storage disorder patient with angiokeratoma corporis diffusum which was discovered by Kanzaki et al. (Kanzaki, T., Yokota, M., Mizuno, N., Matsumoto, Y., and Hirabayashi, Y. (1989) Lancet April 22, 875-877). Based on the results of fast atom bombardment mass spectrometry, methylation analysis, and proton nuclear magnetic resonance spectroscopy, their chemical structures were concluded to be: (formula; see text) The yields of GP-M1, GP-D1, GP-D2, and GP-D3 were approximately 15, 6, 50, and 5 mg/liter of urine, respectively. The most major compound GP-D2, was further purified into single molecular species, threonine and serine type, by reversed phase high performance liquid chromatography. NMR analysis of the two purified compounds with single molecular species showed that the chemical shifts of anomeric protons of GalNAc were significantly different between threonine- and serine-linked GalNAc. Neither mannose-containing glycopeptides nor glycosphingolipids were excreted in the patient urine. From these results, this disease is thought to be caused by the deficiency of a lysosomal enzyme(s) acting on O-linked glycan chains. 相似文献
39.
Human serum deoxyribonuclease I (DNase I) polymorphism: pattern similarities among isozymes from serum, urine, kidney, liver, and pancreas. 总被引:7,自引:0,他引:7 下载免费PDF全文
K Kishi T Yasuda Y Ikehara K Sawazaki W Sato R Iida 《American journal of human genetics》1990,47(1):121-126
We have devised a zymogram method with high sensitivity and resolution for investigating molecular heterogeneity and genetic polymorphism of deoxyribonuclease I. A combination technique of polyacrylamide-gel isoelectric-focusing electrophoresis and the newly developed zymogram method have led to the discovery of genetic polymorphism of human serum DNase I. Family studies showed that the three common phenotypes--DNASE1 1, DNASE1 1-2, and DNASE1 2--and the other five relatively rare phenotypes--DNASE1 1-3, DNASE1 2-3, DNASE1 2-4, and DNASE1 3-4--represent homozygosity or heterozygosity for four autosomal codominant alleles, DNASE1 *1, DNASE1 *2, DNASE1 *3, and DNASE1 *4. The frequencies of DNASE1 *1, DNASE1 *2, DNASE1 *3, and DNASE1 *4 calculated in a Japanese population were .5517, .4358, .0104, and .0021, respectively. Moreover, it was found that urine and extracts of kidney, liver, and pancreas, as well as serum, can be used for DNase I phenotyping. 相似文献
40.