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81.
García-Bonilla L Burda J Piñeiro D Ayuso I Gómez-Calcerrada M Salinas M 《Neurochemical research》2006,31(12):1433-1441
The activation of the [Ca2+]-dependent cysteine protease calpain plays an important role in ischemic injury. Here, the levels of two calpain-specific substrates, p35 protein and eukaryotic initiation factor 4G (eIF4G), as well as its physiological regulator calpastatin, were investigated in a rat model of transient global cerebral ischemia with or without ischemic tolerance (IT). Extracts of the cerebral cortex, whole hippocampus and hippocampal subregions after 30 min of ischemia and different reperfusion times (30 min and 4 h) were used. In rats without IT, the p35 levels slightly decreased after ischemia or reperfusion, whereas the levels of p25 (the truncated form of p35) were much higher than those in sham control rats after ischemia and remained elevated during reperfusion. The eIF4G levels deeply diminished after reperfusion and the decrease was significantly greater in CA1 and the rest of the hippocampus than in the cortex. By contrast, the calpastatin levels did not significantly decrease during ischemia or early reperfusion, but were upregulated after 4 h of reperfusion in the cortex. Although IT did not promote significant changes in p35 and p25 levels, it induced a slight increase in calpastatin and eIF4G levels in the hippocampal subregions after 4 h of reperfusion. 相似文献
82.
Vasile A. Suchar 《Journal of experimental marine biology and ecology》2006,337(1):96-102
Colurella dicentra clones isolated from bay water in the Mississippi Gulf Coast were cultured with artificial seawater. Experiments were conducted to determine the effects of six algae species (Nannochloropsis oculata, Tetraselmis chuii, Chaetoceros gracilis, Rhodomonas salina, Isochrysis galbana, and Prorocentrum micans), six C. gracilis densities, and six N. oculata densities (25,000, 50,000, 100,000, 250,000, 500,000, and 1,000,000 cells ml− 1) on C. dicentra population growth. Algae type influenced rotifer production (p < 0.0001). C. gracilis treatment (9120 ± 3351SD) produced the highest number of rotifers followed by N. oculata (5760 ±2232SD). P. micans had the lowest number of rotifers, although not significantly different from numbers in T. chuii, R. salina, and I. galbana treatments (p > 0.05).The population growth rate (r) varied with algae species treatment. The highest values were recorded for C. gracilis treatment (0.22 to 0.26 d− 1), followed by N. oculata (0.21 to 0.24 d− 1), and the lowest for P. micans (− 0.19 to 0.14 d− 1). C. gracilis and N. oculata densities had significant effects (p < 0.0001) on C. dicentra population growth. The highest rotifer production was recorded at a C. gracilis density of 100,000 cells ml− 1, followed by 250,000 cells ml− 1 and 50,000 cells ml− 1. Algae densities of 500,000 cells ml− 1 and above produced the lowest rotifer numbers. Population growth rate (r) varied with C. gracilis densities. The highest values were observed for C. gracilis concentrations of 100,000 cells ml− 1 (0.17 to 0.19 d− 1), and the lowest for concentrations of 500,000 cells ml− 1 and above (− 0.19 to 0.09 d− 1). The 100,000 cells ml− 1N. oculata density gave the highest rotifer production followed by 50,000, 250,000, 25,000, and 500,000 cells ml− 1. Algae densities of 1,000,000 cells ml− 1 produced the lowest rotifer numbers. Population growth rate (r) varied with N. oculata densities, with the highest values obtained for algae densities of 100,000 cells ml− 1 (0.35 to 0.40 d− 1), and the lowest for concentrations of 1,000,000 cells ml− 1 (0.05 to 0.012 d− 1). This is the first report of C. dicentra in Mississippi Coastal waters, and perhaps the smallest marine rotifer species (93 by 49 μm) ever cultured successfully. 相似文献
83.
Inexpensive non-toxic flocculation of microalgae contradicts theories; overcoming a major hurdle to bulk algal production 总被引:1,自引:0,他引:1
Schlesinger A Eisenstadt D Bar-Gil A Carmely H Einbinder S Gressel J 《Biotechnology advances》2012,30(5):1023-1030
There are two major energy and cost constraints to bulk production of single cell microalgae for biofuels or feed: expensive culture systems with high capital costs and high energy requirements for mixing and gas exchange; and the cost of harvesting using high-speed continuous centrifugation for dewatering. This report deals with the latter; harvesting by flocculation where theory states that alkaline flocculants neutralize the repelling surface charge of algal cells, allowing them to coalesce into a floc. It had been assumed that with such electrostatic flocculation, the more cells to be flocculated, the more flocculant needed, in a linear stoichiometric fashion, rendering flocculation overly expensive. Counter to theory of electrostatic flocculation, we find that the amount of alkaline flocculant needed is a function of the logarithm of cell density, with dense cultures requiring an order of magnitude less base than dilute suspensions, with flocculation occurring at a lower pH. Various other theories abound that flocculation can be due to multi-valent cross-linking, or co-precipitation with phosphate or with magnesium and calcium, but are clearly not relevant with the flocculants we used. Monovalent bases that cannot cross-link or precipitate phosphate work with the same log-linear stoichiometry as the divalent bases, obviating those theories, leaving electrostatic flocculation as the only tenable theory of flocculation with the materials used. The cost of flocculation of dense cultures with this procedure should be below $1.00/T algae for mixed calcium:magnesium hydroxides. 相似文献
84.
《Journal of biological education》2012,46(4):214-217
Department of Physiological Botany, Uppsala University, Uppsala, Sweden Hydrogen gas is regarded as a potential candidate for a future energy economy. Research and development in the field of hydrogen energy is greatly encouraged on all continents. A wide range of microorganisms are able to produce hydrogen gas, among them photosynthetically active organisms that use light as their sole energy source. These organisms are good candidates for the photobiological production of hydrogen gas. Green algae are of particular interest since they are capable of splitting water during photosynthesis and of releasing hydrogen gas under certain conditions. This article describes a small bioreactor that can be run in the classroom and used to demonstrate the concept of photohydrogen production. 相似文献
85.
Bayro MJ Daviso E Belenky M Griffin RG Herzfeld J 《The Journal of biological chemistry》2012,287(5):3479-3484
Functional amyloids have been identified in a wide range of organisms, taking on a variety of biological roles and being controlled by remarkable mechanisms of directed assembly. Here, we report that amyloid fibrils constitute the ribs of the buoyancy organelles of Anabaena flos-aquae. The walls of these gas-filled vesicles are known to comprise a single protein, GvpA, arranged in a low pitch helix. However, the tertiary and quaternary structures have been elusive. Using solid-state NMR correlation spectroscopy we find detailed evidence for an extended cross-β structure. This amyloid assembly helps to account for the strength and amphiphilic properties of the vesicle wall. Buoyancy organelles thus dramatically extend the scope of known functional amyloids. 相似文献
86.
Dmitri Graifer Andrey Zhigailov Aliya Ven’yaminovaAlexey Malygin Bulat IskakovGalina Karpova 《FEBS letters》2012,586(20):3731-3736
The roles of 2′-OH groups in the binding of mRNA to human ribosomes were studied using site-directed cross-linking. We found that both mRNA and mDNA analogues bearing a cross-linker can modify ribosomal proteins (rps) S3e and S2e at the mRNA entry site independently on tRNA presence, but only mRNA analogues were capable of a tRNAPhe-dependent binding to human ribosomes and cross-linking to rpS26e in the mRNA binding centre. Thus, 2′-OH groups of mRNA are unimportant for binding at the entry site but they are crucial for codon-anticodon interactions at the P site, implying the existence of mRNA-ribosome contacts that do not occur in bacteria. 相似文献
87.
Ferrante P Ballottari M Bonente G Giuliano G Bassi R 《The Journal of biological chemistry》2012,287(20):16276-16288
The photosystem II antenna of Chlamydomonas reinhardtii is composed of monomeric and trimeric complexes, the latter encoded by LHCBM genes. We employed artificial microRNA technology to specifically silence the LHCBM2 and LHCBM7 genes, encoding identical mature polypeptides, and the LHCBM1 gene. As a control, we studied the npq5 mutant, deficient in the LHCBM1 protein. The organization of LHCII complexes, functional antenna size, capacity for photoprotection, thermal energy dissipation and state transitions, and resistance to reactive oxygen species was studied in the various genotypes. Silencing of the LHCBM2/7 genes resulted in a decrease of an LHCII protein with an apparent molecular mass of 22 kDa, whereas silencing/lack of LHCBM1 caused the decrease/disappearance of a 23-kDa protein. A decrease in the abundance of trimeric LHCII complexes and in functional antenna size was observed in both LHCBM2/7 and LHCBM1 knockouts. In agreement with previous data, depletion of LHCBM1 decreased the capacity for excess energy dissipation but not the ability to perform state transitions. The opposite was true for LHCBM2/7, implying that this polypeptide has a different functional role from LHCBM1. The abundance of LHCBM1 and LHCBM2/7 is in both cases correlated with resistance to superoxide anion, whereas only LHCBM1 is also involved in singlet oxygen scavenging. These results suggest that different LHCBM components have well defined, non-redundant functions despite their high homology, implying that engineering of LHCBM proteins can be an effective strategy for manipulating the light harvesting system of Chlamydomonas reinhardtii. 相似文献
88.
89.
The Revised Classification of Eukaryotes 总被引:1,自引:0,他引:1
Sina M. Adl Alastair G. B. Simpson Christopher E. Lane Julius Lukeš David Bass Samuel S. Bowser Matthew W. Brown Fabien Burki Micah Dunthorn Vladimir Hampl Aaron Heiss Mona Hoppenrath Enrique Lara Line le Gall Denis H. Lynn Hilary McManus Edward A. D. Mitchell Sharon E. Mozley‐Stanridge Laura W. Parfrey Jan Pawlowski Sonja Rueckert Laura Shadwick Conrad L. Schoch Alexey Smirnov Frederick W. Spiegel 《The Journal of eukaryotic microbiology》2012,59(5):429-514
This revision of the classification of eukaryotes, which updates that of Adl et al. [J. Eukaryot. Microbiol. 52 (2005) 399], retains an emphasis on the protists and incorporates changes since 2005 that have resolved nodes and branches in phylogenetic trees. Whereas the previous revision was successful in re‐introducing name stability to the classification, this revision provides a classification for lineages that were then still unresolved. The supergroups have withstood phylogenetic hypothesis testing with some modifications, but despite some progress, problematic nodes at the base of the eukaryotic tree still remain to be statistically resolved. Looking forward, subsequent transformations to our understanding of the diversity of life will be from the discovery of novel lineages in previously under‐sampled areas and from environmental genomic information. 相似文献
90.
目的:蛇毒纤维蛋白溶解酶能直接溶解纤维蛋白或纤维蛋白原,在心脑血管疾病的治疗方面具有潜在的应用价值。方法:采用双酶切技术从pMD18T-FLE I克隆载体上获得中介蝮蛇毒纤溶酶基因编码区,再将其亚克隆到真核表达载体pFASTBACHTa上,经转化、筛选和鉴定,获得重组真核表达质粒pFASTBACHTa-FLE。重组质粒经小鼠尾静脉快速注入小鼠体内,进行瞬时表达。结果:经SDS-PAGE和Western blot检测,表明在小鼠肝脏组织中有重组FLE蛋白表达。免疫组织化学检测证明该蛋白在小鼠肝脏组织中大量表达。纤维蛋白平板法鉴定该重组蛋白具有较高的纤溶活性,其活性呈现出剂量相关性和时间依赖性。因此为进一步对中介蝮蛇毒纤溶酶的应用奠定了坚实的基础。 相似文献