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81.
Héctor M. Conesa Ahmad B. Moradi Brett H. Robinson Guido Kühne Eberhard Lehmann Rainer Schulin 《Environmental and Experimental Botany》2009,65(2-3):198-204
Mine tailings are an environmental problem in Southern Spain because wind and water erosion of bare surfaces results in the dispersal of toxic metals over nearby urban or agricultural areas. Revegetation with tolerant native species may reduce this risk. We grew two grasses, Lygeum spartum and Piptatherum miliaceum, and the crop species Cicer arietinum (chickpea) under controlled conditions in pots containing a mine tailings mixed into non-polluted soil to give treatments of 0%, 25%, 50%, 75% and 100% mine tailings. We tested a neutral (pH 7.4) mine tailings which contained high concentrations of Cd, Cu, Pb and Zn. Water-extractable metal concentrations increased in proportion to the amount of tailings added. The biomass of the two grasses decreased in proportion to the rate of neutral mine-tailing addition, while the biomass of C. arietinum only decreased in relation to the control treatment. Neutron radiography revealed that root development of C. arietinum was perturbed in soil amended with the neutral tailings compared to those of the control treatment, despite a lack of toxicity symptoms in the shoots. In all treatments and for all metals, the plants accumulated higher concentrations in the roots than in shoots. The highest concentrations occurred in the roots of P. miliaceum (2500 mg kg?1 Pb, 146 mg kg?1 Cd, 185 mg kg?1 Cu, 2700 mg kg?1 Zn). C. arietinum seeds had normal concentrations of Zn (70–90 mg kg?1) and Cu (6–9 mg kg?1). However, the Cd concentration in this species was ~1 mg kg?1 in the seeds and 14.5 mg kg?1 in shoots. Consumption of these plant species by cattle and wild fauna may present a risk of toxic metals entering the food chain. 相似文献
82.
Igor Shuryak Philip Hahnfeldt Lynn Hlatky Rainer K. Sachs David J. Brenner 《Radiation and environmental biophysics》2009,48(3):275-286
As the number of cancer survivors grows, prediction of radiotherapy-induced second cancer risks becomes increasingly important.
Because the latency period for solid tumors is long, the risks of recently introduced radiotherapy protocols are not yet directly
measurable. In the accompanying article, we presented a new biologically based mathematical model, which, in principle, can
estimate second cancer risks for any protocol. The novelty of the model is that it integrates, into a single formalism, mechanistic
analyses of pre-malignant cell dynamics on two different time scales: short-term during radiotherapy and recovery; long-term
during the entire life span. Here, we apply the model to nine solid cancer types (stomach, lung, colon, rectal, pancreatic,
bladder, breast, central nervous system, and thyroid) using data on radiotherapy-induced second malignancies, on Japanese
atomic bomb survivors, and on background US cancer incidence. Potentially, the model can be incorporated into radiotherapy
treatment planning algorithms, adding second cancer risk as an optimization criterion. 相似文献
83.
Rainer Machauer Kurt Laumen Siem Veenstra Jean-Michel Rondeau Marina Tintelnot-Blomley Claudia Betschart Anne-Lise Jaton Sandrine Desrayaud Matthias Staufenbiel Sabine Rabe Paolo Paganetti Ulf Neumann 《Bioorganic & medicinal chemistry letters》2009,19(5):1366-1370
The macrocyclic peptidic BACE-1 inhibitors 2a–c show moderate enzymatic and cellular activity. By exchange of the hydroxyethylene- to ethanolamine-transition state mimetic the peptidic character was reduced, providing the highly potent and selective inhibitor 3. Variation of the P′ moiety resulted in the macrocyclic inhibitor 14. Both macrocycles show inhibition of BACE-1 in the brain of APP51/16 transgenic mice, 3 (NB-544) after intravenous and 14 (NB-533) after oral application. 相似文献
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87.
Waltraud Kaar Karin Ahrer Astrid Dürauer Sabine Greinstetter Wolfgang Sprinzl Philipp Wechner Franz Clementschitsch Karl Bayer Clemens Achmüller Bernhard Auer Rainer Hahn Alois Jungbauer 《Biotechnology and bioengineering》2009,104(4):774-784
The autoprotease Npro significantly enhances expression of fused peptides and proteins and drives the formation of inclusion bodies during protein expression. Upon refolding, the autoprotease becomes active and cleaves itself specifically at its own C‐terminus releasing the target protein with its authentic N‐terminus. Npro wild‐type and its mutant EDDIE, respectively, were fused N‐terminally to the model proteins green fluorescent protein, staphylococcus Protein A domain D, inhibitory peptide of senescence‐evasion‐factor, and the short 16 amino acid peptide pep6His. In comparison with the Npro wild‐type, the tailored mutant EDDIE displayed an increased rate constant for refolding and cleavage from 1.3 × 10?4 s?1 to 3.5 × 10?4 s?1, and allowed a 15‐fold higher protein concentration of 1.1 mg/mL when studying pep6His as a fusion partner. For green fluorescent protein, the rate constant was increased from 2.4 × 10?5 s?1 to 1.1 × 10?4 s?1 when fused to EDDIE. When fused to small target peptides, refolding and cleavage yields were independent of initial protein concentration, even at high concentrations of 3.9 mg/mL, although cleavage rates were strongly influenced by the fusion partner. This behavior differed from conventional 1st order refolding kinetics, where yield strongly depends on initial protein concentration due to an aggregation reaction of higher order. Refolding and cleavage of EDDIE fusion proteins follow a monomolecular reaction for the autoproteolytic cleavage over a wide concentration range. At high protein concentrations, deviations from the model assumptions were observed and thus smaller rate constants were required to approximate the data. Biotechnol. Bioeng. 2009; 104: 774–784 © 2009 Wiley Periodicals, Inc. 相似文献
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89.
Functional genomics of phosphate antiport systems of plastids 总被引:4,自引:0,他引:4
Ulf-Ingo Flügge Rainer E. Häusler Frank Ludewig Karsten Fischer 《Physiologia plantarum》2003,118(4):475-482
Plant cells require a co-ordination of metabolism between their major compartments, the plastids and the cytosol, in particular as certain metabolic pathways are confined to either compartments. The inner envelope membrane of the plastids forms the major barrier for metabolite exchange and is the site for numerous transport proteins, which selectively catalyse metabolite exchanges characteristic for green and/or non-green tissues. This report is focused on the molecular biology, evolution and physiological function of the family of phosphate translocators (PT) from plastids. Until now, four distinct subfamilies have been identified and characterized, which all share inorganic phosphate as common substrate, but have different spectra of counter exchange substrates to fulfil the metabolic needs of individual cells and tissues. The PTs are named after their main transported substrate, triose phosphate (TPT), phosphoenolpyruvate (PPT), glucose 6-phosphate (GPT) and xylulose 5-P (XPT). All PTs belong to the TPT/nucleotide sugar transporter (NST) superfamily, which includes yet uncharacterized PT homologues from plants and other eukaryotes. Transgenic plants or mutants with altered transport activity of some of the PTs have been generated or isolated. The analysis of these plant lines revealed new insights in the co-ordination and flexibility of plant metabolism. 相似文献
90.
Rainer R. Schoch 《Palaeontology》2003,46(5):1055-1072
The early larval development of the temnospondyl Sclerocephalus sp. is analyzed, based on 38 specimens from the Lower Rotliegend (Permo-Carboniferous boundary) of the Saar-Nahe Basin (south-west Germany). The study focuses on the smallest larval specimens, which exemplify changes in both proportions and ossification patterns. In comparison with dissorophoid larvae, the skull ossifies more fully and at a much faster rate; the smallest specimens already have completely formed circumorbital bones that are sutured throughout. Sculpturing undergoes two marked changes, first from uniformly pitted to pits of variable size and regional differentiation, and finally to the origin of ridges. The palate of small larvae differs from that of larger specimens in patterns of dentition, having more teeth including a denticle field on the cultriform process. The mandible of small larvae is described for the first time, being narrower than in adults and having three dentigerous coronoid elements. The smallest specimens have poorly ossified neural arches, lack vertebral centra, and have faintly ossified humeri, femora, and very poorly developed distal elements. The posterior ribs, metapodia, and phalanges appeared after the dermal elements of the pectoral girdle, whereas the scapulocoracoid and ischium are absent throughout the larval period. Early growth and differentiation of the limbs and the ilium illustrates the developmental patterning of the appendages, which proceeded from proximal to distal. Dermal squamation is uniform in small stages, consisting of round or oval osteoderms with pronounced growth rings; in large larvae, they start to differentiate in certain body regions. 相似文献