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311.
Plant Communities, Soil Microorganisms, and Soil Carbon Cycling: Does Altering the World Belowground Matter to Ecosystem Functioning? 总被引:7,自引:0,他引:7
Soil microorganisms mediate many critical ecosystem processes. Little is known, however, about the factors that determine
soil microbial community composition, and whether microbial community composition influences process rates. Here, we investigated
whether aboveground plant diversity affects soil microbial community composition, and whether differences in microbial communities
in turn affect ecosystem process rates. Using an experimental system at La Selva Biological Station, Costa Rica, we found
that plant diversity (plots contained 1, 3, 5, or > 25 plant species) had a significant effect on microbial community composition
(as determined by phospholipid fatty acid analysis). The different microbial communities had significantly different respiration
responses to 24 labile carbon compounds. We then tested whether these differences in microbial composition and catabolic capabilities
were indicative of the ability of distinct microbial communities to decompose different types of litter in a fully factorial
laboratory litter transplant experiment. Both microbial biomass and microbial community composition appeared to play a role
in litter decomposition rates. Our work suggests, however, that the more important mechanism through which changes in plant
diversity affect soil microbial communities and their carbon cycling activities may be through alterations in their abundance
rather than their community composition. 相似文献
312.
稀土氧化镧对黄粉虫生长发育和繁殖的影响 总被引:4,自引:0,他引:4
制备每kg麦麸分别含10,20,30,40,50,60,100,150,200和300mg氧化镧的饲料,用这10种剂量的饲料分别连续饲喂1日龄的黄粉虫TenebriomolitorL.幼虫和成虫。用40mg氧化镧kg麦麸的剂量处理79d后幼虫体重比对照组增加43%,同样的剂量使产卵高峰期的雌虫日平均产卵量增加59%,是最佳的处理剂量。自1日龄起连续取食50d最佳剂量氧化镧的幼虫,体内蓄积有0.4%的镧元素。用最佳剂量氧化谰处理黄粉虫在经济上具有很高的投入-产出比。 相似文献
313.
Apoptosis is mediated by an intracellular biochemical system that mainly includes proteins (procaspases, caspases, inhibitors, Bcl-2 protein family as well as substances released from mitochondrial intermembrane space). The dynamics of caspase activation and target cleavage in apoptosis induced by granzyme B in a single K562 cell was studied using a mathematical model of the dynamics of granzyme B-induced apoptosis developed in this work. Also the first application of optimization approach to determination of unknown kinetic constants of biochemical apoptotic reactions was presented. The optimization approach involves solving of two problems: direct and inverse. Solving the direct optimization problem, we obtain the initial (baseline) concentrations of procaspases for known kinetic constants through conditional minimization of a cost function based on the principle of minimum protein consumption by the apoptosis system. The inverse optimization problem is aimed at determination of unknown kinetic constants of apoptotic biochemical reactions proceeding from the condition that the optimal concentrations of procaspases resulting from the solution of the direct optimization problem coincide with the observed ones, that is, those determined by biochemical methods. The Multidimensional Index Method was used to perform numerical solution of the inverse optimization problem. 相似文献
314.
JUAN L. CELIS-DIEZ RAMIRO O. BUSTAMANTE RODRIGO A. VÁSQUEZ 《Biological journal of the Linnean Society. Linnean Society of London》2004,81(2):307-312
Seed size is a life history attribute that affects the probability of seed predation, and therefore affects plant fitness. Compared with smaller seeds, those with large size should be more attractive to predators, as they constitute a more profitable food item because of higher energetic and/or nutrient content. However, predator preferences may be frequency-dependent in the sense that they may be modulated by the relative abundance of alternative seeds of different sizes. We set up a field experiment to evaluate frequency-dependent seed predation using seeds of Cryptocarya alba (Lauraceae), at La Campana National Park in central Chile. Predators (rodents and birds) preferentially consumed large seeds in an antiapostatic manner. These selective responses were maintained throughout the experiment and seed selection by predators was not affected by previous seed consumption. Our results suggest that (a) large seeds are very profitable food items actively sought by seed predators even at low relative abundance, (b) seed selection is expressed in a short time scale and (c) seed predators, by consuming large seeds consistently, have the potential to modify significantly the quality of plant progeny. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 307–312. 相似文献
315.
稀土多元复合肥和三种稀土元素的遗传毒性研究 总被引:24,自引:3,他引:21
采用蚕豆根尖细胞微核技术,研究市售稀土多元复合肥和稀土元素镧、铈、铒的化合物对蚕豆根尖细胞的遗传毒性和细胞毒性。结果表明,稀土复合肥和三种稀土元素均可诱发微核效应,在一定浓度下可损伤细胞,影响根尖的正常生长,其中稀土复合肥的微核效应表现出明显的剂量-效应关系。稀土复合肥和稀土元素镧、铈、铒的化合物对蚕豆根尖细胞具有一定的遗传毒性作用和细胞毒性作用,在施用稀土微肥和使用稀土制品时应引起重视。
Abstract:This paper presents the study of genetic toxicity and cell toxicity that is give n by rare earth multi-element compound fertilizer and a chemical compound of rar e earth elements-La3+、Ce4+、Er3+ in root tip cells of Vicia faba.The technique used is micronucleus in root tip cells of Vicia faba.The experiment statistical result shows that both the rare earth compound fertilizer and the three kinds of rare earth elements can cause micronucleus ef fect and under certain concentration,they can hurt cells, affect root tip gro wth .The micronucleus effect of the rare earth compound fertilizer shows a clear relation of dosage-effect. The conclusion is that rare earth compound fertilize r and the chemical compound of rare earth elements La3+、Ce4+、E r3+cause certain genetic toxicity and cell toxicity effect to root tip cells of Vicia faba.Therefore a close attention should be paid when the rar e earth multi-fertilizer and other things made by rare earth are used. 相似文献
316.
Recent strong El Niño‐Southern Oscillation (ENSO) signals have been identified in precipitation records from the Iberian Peninsula. Interannual association with ENSO accounts for more than half the total annual variance in selected stations of the south‐east, with ENSO leading rainfall by one year. In contrast, association with the North Atlantic Oscillation (NAO) at the Westernmost stations is much lower (25%). The potential of simple linear models is tested in the ENSO‐sensitive area, suggesting high capability of the Southern Oscillation Index (SOI) for predicting interannual rainfall fluctuations (mainly droughts and floods). Wine quality is associated with several factors, e.g. grape variety, soil type and processing, which can be considered invariable, mainly due to the strict regulations imposed by the quality regulating councils. Climate, however, has a great influence on resulting wine quality, and represents the most important source of variability at both short (day‐to‐day) and long (interannual) time scales. Over the last 30 years, high‐quality harvests in the five main wine regions in Spain, show a high probability (P < 0.0002) of being associated with an El Niño event occurring the same year or the year before. NAO influence is not significant during the same period. Thus, apart from considering the role of local climatic conditions in certain regions, which favour the production of excellent wines, larger‐scale climatic phenomena appear responsible for the year‐to‐year variations in quality. 相似文献
317.
318.
Tanaka Y Nakamura M Matsui T Iizuka N Kondo H Tohma S Masuko K Yudoh K Nakamura H Nishioka K Koizuka I Kato T 《Microbiology and immunology》2006,50(2):117-126
Relapsing polychondritis (RP) is a systemic inflammatory disease, in which autoimmunity to cartilage-related components is thought to be involved in its pathogenesis. However, the autoimmune profile in RP has not been studied fully. We therefore investigated autoantibodies/autoantigens in RP comprehensively, by 2-dimensional electrophoresis (2DE), subsequent western blotting (WB) and mass spectrometry, using cell-extracted proteins as the antigen source. As a result, we detected 15 autoantigens on 2DE-WB, and further identified five of them. On average, one RP serum recognized approximately 8 out of the 15 autoantigens. Frequencies of the autoantibodies to the 5 identified antigens of tubulin alpha ubiquitous/6, vimentin, alpha enolase, calreticulin, and colligin-1/-2 were 91%, 46%, 36%, 82%, and 36%, respectively. ELISA using recombinant proteins for them revealed that frequencies of the autoantibodies to tubulin alpha ubiquitous, vimentin, alpha enolase, calreticulin, and colligin-1 were 36%, 64%, 46%, 27%, and 18%, respectively. Our data demonstrated that the autoimmune reaction was not restricted to cartilagerelated components, rather a variety of autoimmune responses occurred in patients with RP, which may be involved in the pathophysiology of RP. In addition, the proteomic approach using cell-extracted proteins would be a powerful way to investigate autoantigens. 相似文献
319.
Petr Pokorný Nicole Boenke Miloslav Chytráček Kateřina Nováková Jiří Sádlo Josef Veselý Petr Kuneš Vlasta Jankovská 《Vegetation History and Archaeobotany》2006,15(4):419-433
The large fortified hilltop site of Vladař, northwest Bohemia, Czech Republic (50°05′N, 13°13′E), has recently been studied intensively by way of environmental archaeology, in which palaeoecological methods have played a crucial role. The latter include the analyses of pollen, green algae, Cladocera, other microfossils, plant macro-remains (including charcoal and wood) and chemical composition, carried out on the wet sediments from an artificial cistern/pond situated in the middle of the large citadel, supplemented by charcoal and wood analysis on material from dry situations. The continuous palaeoecological record consists of well-preserved biological remains and covers the period from ca. 400 b.c. to recent times. The chronology is primarily based on radiocarbon dating, supplemented by archaeological finds. The main focus is on the La Tène period of the Iron Age. During the early to middle La Tène the hillfort had a considerable number of permanent inhabitants and woodland was almost completely replaced by an agricultural landscape. The site became partly abandoned by the end of the 3rd century b.c. and completely abandoned around the birth of Christ, after which it reverted to natural woodland communities. 相似文献
320.
Chryssa Voitharou Dimitrios Krikorian Constantinos Sakarellos Maria Sakarellos-Daitsiotis Eugenia Panou-Pomonis 《Journal of peptide science》2008,14(9):1069-1076
Complementary peptide epitopes, derived from complementary RNA sequences, have been used for suppressing the autoimmune response in experimental autoimmune diseases as myasthenia gravis, allergic neuritis and allergic encephalomyelitis. Aiming at contributing to the development of a tool that could regulate the autoantibody production against La/SSB, which is the main target of autoantibodies in Sjogren's syndrome (SS) and systemic lupus erythematosus (SLE), the complementary epitope, cpep349-364, of the minor T/major B cell epitope of La/SSB, pep349-364, was utilized for the induction of neutralizing anti-cpep349-364 antibodies in rabbit immunizations. Complementary peptides were coupled to an artificial carrier, developed in our laboratory, in order to enhance the complementary potency of cpep349-364 and its counterpart. This carrier, named Sequential Oligopeptide Carrier, SOC(n), formed by the repeating tripeptide Lys-Aib-Gly, adopts helical conformation, which allows the anchored peptide epitopes to preserve their initial reactivity such as molecular recognition, antigenicity/immunogenicity. Our study provides proof of evidence of specific interactions between idiotypic (Id)/anti-idiotypic (anti-Id) antibodies generated in immunized animals by the sense epitope (conjugate I) of La/SSB and its complementary counterpart (conjugate II). It was also demonstrated that the Id/anti-Id association is specifically disrupted by adding either the sense epitope (conjugate I) or its complementary counterpart (conjugate II). A mutual neutralization of Id/anti-Id antibodies was observed in vivo, which implies that generation of anti-Id antibodies by immunization with the complementary La/SSB epitope could scavenge the anti-La/SSB response. Copyright (c) 2008 European Peptide Society and John Wiley & Sons, Ltd. 相似文献