全文获取类型
收费全文 | 939篇 |
免费 | 85篇 |
国内免费 | 9篇 |
出版年
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 13篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 38篇 |
2017年 | 23篇 |
2016年 | 26篇 |
2015年 | 28篇 |
2014年 | 66篇 |
2013年 | 64篇 |
2012年 | 39篇 |
2011年 | 42篇 |
2010年 | 46篇 |
2009年 | 38篇 |
2008年 | 65篇 |
2007年 | 59篇 |
2006年 | 38篇 |
2005年 | 36篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
排序方式: 共有1033条查询结果,搜索用时 312 毫秒
11.
A cDNA clone encoding a major chloroplast inner envelope membrane protein of 96 kDa (IEP96) was isolated and characterized. The protein is synthesized as a larger-molecular-weight precursor (pIEP96) which contains a cleavable N-terminal transit sequence of 50 amino acids. The transit peptide exhibits typical stromal targeting information. It is cleaved in vitro by the stromal processing peptidase, though the mature protein is clearly localized in the inner envelope membrane. Translocation of pIEP96 into chloroplasts is greatly stimulated in the presence of 80 mM potassium phosphate which results in an import efficiency of about 90%. This effect is specific for potassium and phosphate, but cannot be ascribed to a membrane potential across the inner envelope membrane. Protein sequence analysis reveals five stretches of repeats of 26 amino acids in length. The N-terminal 300 amino acids are 45% identical (76% similarity) to the 35 kDa -subunit of acetyl-CoA carboxyl-transferase from Escherichia coli. The C-terminal 500 amino acids share significant similarity (69%) with USOI, a component of the cytoskeleton in yeast.Abbreviations Pi
phosphate
- IEP
inner envelope membrane protein
- pIEP
precursor form of IEP
- SSU
small subunit of ribulose-1,5-bisphosphate carboxylase oxygenase
- IEP96pep
peptide specific antiserum to IEP96
- IEP96pol
polyspecific antiserum to IEP96 相似文献
12.
Raju Rajala V. S. Magnuson Bernadene A. Sharma Rajendra K. 《Molecular and cellular biochemistry》1995,149(1):191-202
Myristoyl CoA:Protein N-myristoyltransferase (NMT) is the enzyme which catalyses the covalent transfer of myristate from myristoyl CoA to the amino-terminal glycine residue of protein substrates. Although NMT is ubiquitous in eukaryotic cells, the enzyme levels and cellular distribution vary among tissues. In this article, we describe the properties of mammalian NMT(s) with reference to subcellular distribution, molecular weights, substrate specificity and the possible involvement of NMT in pathological processes. The cytosolic fraction of bovine brain contains multiple forms of NMT activity whereas bovine spleen contains only a single form. In bovine brain and spleen, the cytosol contained majority of NMT activity. In contrast, rabbit colon and rat liver NMT activity was predominantly particulate. Regional differences in NMT activity have been observed in both rabbit intestine and bovine brain. Results from our laboratory along with the existing knowledge, provide evidence for the existence of tissue specific isozymes of NMT. 相似文献
13.
Christelle David Laurent Bischoff Hervé Meudal Catherine Llorens-Cortes Bernard Pierre Roques Marie-Claude Fournié-Zaluski 《Letters in Peptide Science》1997,4(4-6):411-414
In order to study the physiological role of aminopeptidase A (APA),several -mercapto--amino acyl dipeptides were synthesized toobtain compounds having a high affinity for APA and a high selectivityversus aminopeptidase N (APN). Sulfonamide and carboxylate moieties whichhave been shown to be recognized by the S1 subsite of theenzyme were introduced on the side chain of the -mercapto--aminoacyl sub-unit, the latter being coupled to dipeptides optimized to interactwith the S1 andS2 subsites by means of combinatorialchemistry. Good affinities (16 nM) were obtained, the selectivity factorsbeing up to 160-fold versus APN. 相似文献
14.
K. A. Buss C. Ingram-Smith J. G. Ferry D. A. Sanders M. S. Hasson 《Protein science : a publication of the Protein Society》1997,6(12):2659-2662
The unique biochemical properties of acetate kinase present a classic conundrum in the study of the mechanism of enzyme-catalyzed phosphoryl transfer. Large, single crystals of acetate kinase from Methanosarcina thermophila were grown from a solution of ammonium sulfate in the presence of ATP. The crystals diffract to beyond 1.7 A resolution. Analysis of X-ray data from the crystals is consistent with a space group of C2 and unit cell dimensions a = 181 A, b = 67 A, c = 83 A, beta = 103 degrees. Diffraction data have been collected from the crystals at 110 and 277 K. Data collected at 277 K extend to lower resolution, but are more reproducible. The orientation of a noncrystallographic two-fold axis of symmetry has been determined. Based on an analysis of the predicted amino acid sequences of acetate kinase from several organisms, we hypothesize that acetate kinase is a member of the sugar kinase/actin/hsp70 structural family. 相似文献
15.
16.
Seven-day-old leek seedlings actively synthesize lipids in vivo from [1-14C]acetate, both in the light and in the dark. In the dark, phospholipid synthesis is more effective than galactolipid synthesis. Whatever the time of acetate incorporation by the etiolated seedlings, very long chain fatty acids having from 20 to 26 carbon atoms are found in all the polar lipids, including the acyl-CoAs. All of the labelled very long chain fatty acids incorporated into the polar lipids are saturated. On the other hand, the labelled C18-fatty acids are unsaturated in phospholipids and galactolipids and almost no label is found in the saturated or unsaturated C18-fatty acids of the acyl-CoAs. 相似文献
17.
18.
Acetyl coenzyme A (CoA) biosynthesis in spinach chloroplasts has been investigated by following the incorporation of bicarbonate and acetate into fatty acids under a variety of conditions. Both substrates were readily incorporated into fatty acids in a light-dependent manner by intact photosynthesising chloroplasts, but when the concentrations of these substrates were adjusted to those found in vivo, i.e. 200 M acetate, 10 M bicarbonate, then acetate was found to supply carbon atoms for fatty acids biosynthesis via acetyl CoA at forty times the rate of bicarbonate. It is proposed that extra-chloroplastic free acetate is the pricipal substrate for chloroplasts acetyl CoA biosynthesis in spinach.Abbreviations ACP
acyl carrierprotein
- CoASH
coenzyme A 相似文献
19.
Acetate uptake by strains of Synechococcus and Aphanocapsa in short experiments required light, and was strongly inhibited by m-dichlorocarbonyl cyanide phenylhydrazone and dichlorophenyl dimethyl urea. Acetate carbon was distributed in amino acids and in the acyl portion of lipids in the same way as during growth experiments when CO2 was available, but the reduced incorporation in the absence of CO2 was primarily into the lipid fraction. An apparent K
m for uptake by Synechococcus and for Aphanocapsa 6308 of 20 and 180 M at pH 7.4 was obtained; corresponding V
max values were 6 and 11 nmol x min-1 x mg protein-1. Uptake with Synechococcus was affected by pH, with affinity decreased and maximal rate increase with rising pH. Acetate uptake was not affected by propionate or butyrate when both were added at the same time, but a light and concentration dependent inhibition developed if suspensions were preincubated with propionate. Acetate carbon moved rapidly into acid insoluble material, but after 10–15 s 75% or more of the recovered intracellular counts were in acetyl CoA. Counts in this compound were reduced by preincubation with propionate.Kinetic measurements of acetyl CoA synthetase in fractionated cell extracts gave values for K
m of about 50 M for acetate, 5 mM for propionate, 100 M for CoA and 0.38 mM for ATP. The internal pool of free CoA was measured to be about 20 M, and was reduced by preincubation with propionate. This suggests that the activity of CoA-mediated reactions may be regulated by the availability of this cofactor.Abbreviations Used CCCP
m-Dichlorocarbonyl cyanide phenyl hydrazone
- DCMU
dichlorophenyl dimethyl urea
- TCA
trichloroacetic acid
- Tris
trishydroxymethyl amino methane
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethane-sulfonic acid 相似文献
20.
Further work on the subcellular localization of two lipid-degrading enzymes, lipolytic acyl hydrolase (LAH) and lipoxygenase (LOX) has been carried out on brassica florets, potato shoots and pea roots. In all cases, the LAH profile on sucrose and Ficoll density gradients was coincident with ‘lysosomal’ acid phosphatase activity. However, the localization of LOX activity was different for each tissue. In pea roots the activity of LOX was localized in the ‘lysosomal’ fraction, whereas with brassica florets (cauliflower and calabrese) it was present in a heavy body with a similar density to plastids and in potato shoots LOX gave only low particulate recoveries. 相似文献