全文获取类型
收费全文 | 231篇 |
免费 | 35篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 13篇 |
2012年 | 12篇 |
2011年 | 7篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 2篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 5篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 6篇 |
1969年 | 3篇 |
排序方式: 共有266条查询结果,搜索用时 31 毫秒
1.
2.
Monoclonal antibodies to the light-harvesting chlorophyll a/b protein complex of photosystem II 总被引:19,自引:3,他引:16 下载免费PDF全文
A collection of 17 monoclonal antibodies elicited against the light-harvesting chlorophyll a/b protein complex which serves photosystem II (LHC-II) of Pisum sativum shows six classes of binding specificity. Antibodies of two of the classes recognize a single polypeptide (the 28- or the 26- kD polypeptides), thereby suggesting that the two proteins are not derived from a common precursor. Other classes of antibodies cross-react with several polypeptides of LHC-II or with polypeptides of both LHC-II and the light-harvesting chlorophyll a/b polypeptides of photosystem I (LHC-I), indicating that there are structural similarities among the polypeptides of LHC-II and LHC-I. The evidence for protein processing by which the 26-, 25.5-, and 24.5-kD polypeptides are derived from a common precursor polypeptide is discussed. Binding studies using antibodies specific for individual LHC-II polypeptides were used to quantify the number of antigenic polypeptides in the thylakoid membrane. 27 copies of the 26-kD polypeptide and two copies of the 28-kD polypeptide were found per 400 chlorophylls. In the chlorina f2 mutant of barley, and in intermittent light-treated barley seedlings, the amount of the 26-kD polypeptide in the thylakoid membranes was greatly reduced, while the amount of 28-kD polypeptide was apparently not affected. We propose that stable insertion and assembly of the 28-kD polypeptide, unlike the 26-kD polypeptide, is not regulated by the presence of chlorophyll b. 相似文献
3.
δ-Tocopherylquinone (δTQ) content was determined in tobacco and yellow maple leaves, green ivy leaves and cactus tissues. It was found that the concentration of δ-TQ was highest in mature or senescent tissues, such as white tobacco leaves (0.02 μmole/g dry wt) while its detection was uncertain in young, green leaves from the apex of tobacco plants. Fractionation by centrifugation of senescent tobacco leaves showed that the osmiophilic globule fraction was enriched in δ-TQ. Electron microscope studies of young, mature and senescent tobacco tissues showed progressive changes in the size and number of osmiophilic globules. After chloroplast breakdown in senescent tobacco leaves, these globules became the predominant constituents of the organelle. δ-TQ which is associated with osmiophilic globules may play a role in the development of plants, particularly during senescence. 相似文献
4.
delta-Tocopherylquinone (deltaTQ) content was determined in tobacco and yellow maple leaves, green ivy leaves and cactus tissues. It was found that the concentration of delta-TQ was highest in mature or senescent tissues, such as white tobacco leaves (0.02 mumole/g dry wt) while its detection was uncertain in young, green leaves from the apex of tobacco plants. Fractionation by centrifugation of senescent tobacco leaves showed that the osmiophilic globule fraction was enriched in delta-TQ. Electron microscope studies of young, mature and senescent tobacco tissues showed progressive changes in the size and number of osmiophilic globules. After chloroplast breakdown in senescent tobacco leaves, these globules became the predominant constituents of the organelle. delta-TQ which is associated with osmiophilic globules may play a role in the development of plants, particularly during senescence. 相似文献
5.
A Photosystem-II (PS-II)-enriched chloroplast submembrane fraction has been subjected to non-denaturing gel-electrophoresis. Two chlorophyll a (Chl a)-binding proteins associated with the core complex were isolated and spectrally characterized. The Chl protein with apparent apoprotein mass of 47 kDa (CP47) displayed a 695 nm fluorescence emission maximum (77 K) and light-induced absorption characteristics indicating the presence of the reaction center Chl, P-680, and its primary electron acceptor, pheophytin. A Chl protein of apparent apoprotein mass of 43 kDa (CP43) displayed a fluorescence emission maximum at 685 nm. We conclude that CP43 serves as an antenna Chl protein and the PS II reaction center is located in CP47. 相似文献
6.
Modification of Herbicide Binding to Photosystem II in Two Biotypes of Senecio vulgaris L 总被引:12,自引:7,他引:5 下载免费PDF全文
The present study compares the binding and inhibitory activity of two photosystem II inhibitors: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron [DCMU]) and 2-chloro-4-(ethylamine)-6-(isopropyl amine)-S-triazene (atrazine). Chloroplasts isolated from naturally occurring triazine-susceptible and triazine-resistant biotypes of common groundsel (Senecio vulgaris L.) showed the following characteristics. (a) Diuron strongly inhibited photosynthetic electron transport from H2O to 2,6-dichlorophenolindophenol in both biotypes. Strong inhibition by atrazine was observed only with the susceptible chloroplasts. (b) Hill plots of electron transport inhibition data indicate a noncooperative binding of one inhibitor molecule at the site of action for both diuron and atrazine. (c) Susceptible chloroplasts show a strong diuron and atrazine binding (14C-radiolabel assays) with binding constants (K) of 1.4 × 10−8 molar and 4 × 10−8 molar, respectively. In the resistant chloroplasts the diuron binding was slightly decreased (K = 5 × 10−8 molar), whereas no specific atrazine binding was detected. (d) In susceptible chloroplasts, competitive binding between radioactively labeled diuron and non-labeled atrazine was observed. This competition was absent in the resistant chloroplasts. 相似文献
7.
Depolarization of the Electrogenic Transmembrane Electropotential of Zea mays L. by Bipolaris (Helminthosporium) maydis Race T Toxin, Azide, Cyanide, Dodecyl Succinic Acid, or Cold Temperature 总被引:5,自引:5,他引:0 下载免费PDF全文
The transmembrane electrical potential of root cells of Zea mays L. cv. W64A in a modified 1× Higinbotham solution was partially depolarized by semipurified toxin obtained from Bipolaris (Helminthosporium) maydis race T. At a given toxin concentration depolarization of Texas cytoplasm cells was much greater than for normal cytoplasm cells. This observation correlated directly to the differential host susceptibility to the fungus. The time course and magnitude of depolarization were dependent on toxin concentration; at high concentration the electropotential difference change was rapid. Cortex cells depolarized more slowly than epidermal cells indicating that the toxin slowly permeated intercellular regions. Toxin concentrations which affected electropotential difference were of the same magnitude as those required to inhibit root growth, ion uptake, and mitochondrial processes.
Azide, cyanide, and cold temperature (5 C) gave the same partial depolarization as did the toxin. Dodecyl succinic acid caused complete depolarization. These and other data indicate that one of the primary actions of the toxin is to inhibit electrogenic ion pumps in the plasmalemma.
相似文献8.
An isolated light-harvesting pigment-protein complex contains polypeptides which bind chlorophyll a and b. The individual complexes can be purified from detergent-solubilized membranes. The isolated light-harvesting complex, when dialyzed to remove detergents, was examined by freeze-fracture electron microscopy. The material consisted of planar sheets of 80-Å subunits which interacted via an edge-to-edge contact. Addition of cations caused the planar light-harvesting complex sheets to become tightly appressed in multilamellar stacks, with distinct subunits still visible within each lamellar sheet. A transition of particle organization from random to crystalline occurred in parallel with the cation-induced lamellar association. Treatment of the dialyzed light-harvesting complex subunits with low levels of the proteolytic enzyme trypsin removed a 2000 molecular weight segment of the major polypeptide of the light-harvesting complex and blocked all subsequent cation-induced changes in structural organization of the isolated light-harvesting complex lamellar sheets.To gain further evidence for mechanisms of cation effects upon the organization of the light-harvesting complex in native membranes, the light-harvesting complex was incorporated into uncharged (phosphatidylcholine) lipid vesicles. The protein complexes spanned the lipid bilayer and were arranged in either a random pattern or in hexagonal crystalline lattices. Addition of either monovalent or divalent cations to ‘low-salt’ (20 mM monovalent cation) vesicles containing light-harvesting complex caused extensive regions of membrane appression to appear. It is concluded that this cation-induced membrane appression is mediated by surface-exposed segments of the light-harvesting complex since (a) phosphatidylcholine vesicles themselves did not undergo cation-induced aggregation, and (b) mild trypsin digestion of the surface-exposed regions of the light-harvesting complex blocked cation-induced lamellar appression. The particles in the appressed vesicle membranes tended to form long, linear arrays of particles, with occasional mixed quasi-crystalline arrays with an angular displacement near 72°. Surface-mediated interactions among light-harvesting complex subunits of different membranes are, therefore, related to changes in structural organization and interaction of the particles within the lipid phase of the membrane.Numerous previous studies have implicated the involvement of the light-harvesting complex in mediating grana stocking in intact chloroplast membranes. The data presented herein provide a simulation of the membrane appression phenomena using a single class of chloroplast-derived membrane subunits. The data demonstrate that specific surface-localized regions of the light-harvesting complex are involved in membrane-membrane interactions. 相似文献
9.
Summary An inhibition of root growth, a decrease in the amount of potassium (as 86Rb) and phosphate (32P) accumulation by the root, and a partial depolarization of transmembrane electropotential were observed to develop with a similar time course and to a similar extent when intact maize (Zea mays L.) roots were treated with 10-5 M abscisic acid (ABA). Potassium uptake was inhibited by ABA when excised, low-salt roots were bathed in KCl, KH2PO4, or K2SO4. ABA did not affect the ATP content of the tissues, the activity of isolated mitochondria, nor the activity of microsomal K+-stimulated ATPases. 相似文献
10.
The results described in the accompanying article support the model in
which glucosylphosphoryldolichol (Glc-P-Dol) is synthesized on the
cytoplasmic face of the ER, and functions as a glucosyl donor for three
Glc-P-Dol:Glc0-2Man9-GlcNAc2-P-P-Dol glucosyltransferases (GlcTases) in the
lumenal compartment. In this study, the enzymatic synthesis and structural
characterization by NMR and electrospray-ionization tandem mass
spectrometry of a series of water-soluble beta-Glc-P-Dol analogs containing
2-4 isoprene units with either the cis - or trans - stereoconfiguration in
the beta-position are described. The water- soluble analogs were (1) used
to examine the stereospecificity of the Glc-P-Dol:Glc0-2Man9GlcNAc2-P-P-Dol
glucosyltransferases (GlcTases) and (2) tested as potential substrates for
a membrane protein(s) mediating the transbilayer movement of Glc-P-Dol in
sealed ER vesicles from rat liver and pig brain. The Glc-P-Dol-mediated
GlcTases in pig brain microsomes utilized [3H]Glc-labeled Glc-P-Dol10,
Glc-P-(omega, c )Dol15, Glc-P(omega, t,t )Dol20, and Glc-P-(omega, t,c
)Dol20as glucosyl donors with [3H]Glc3Man9GlcNAc2-P-P-Dol the major product
labeled in vitro. A preference was exhibited for C15-20 substrates
containing an internal cis -isoprene unit in the beta-position. In
addition, the water-soluble analog, Glc-P-Dol10, was shown to enter the
lumenal compartment of sealed microsomal vesicles from rat liver and pig
brain via a protein-mediated transport system enriched in the ER. The
properties of the ER transport system have been characterized. Glc-
P-Dol10was not transported into or adsorbed by synthetic PC-liposomes or
bovine erythrocytes. The results of these studies indicate that (1) the
internal cis -isoprene units are important for the utilization of Glc-P-Dol
as a glucosyl donor and (2) the transport of the water- soluble analog may
provide an experimental approach to assay the hypothetical "flippase"
proposed to mediate the transbilayer movement of Glc-P-Dol from the
cytoplasmic face of the ER to the lumenal monolayer.
相似文献