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941.
Embryonic development requires exquisite regulation of several essential processes, such as patterning of tissues and organs, cell fate decisions, and morphogenesis. Intriguingly, these diverse processes are controlled by only a handful of signalling pathways, and mis-regulation in one or more of these pathways may result in a variety of congenital defects and diseases. Consequently, investigating how these signalling pathways are regulated at the molecular level is essential to understanding the mechanisms underlying vertebrate embryogenesis, as well as developing treatments for human diseases. Here, we designed and performed a large-scale gain-of-function screen in Xenopus embryos aimed at identifying new regulators of MAPK/Erk, PI3K/Akt, BMP, and TGF-β/Nodal signalling pathways. Our gain-of-function screen is based on the identification of gene products that alter the phosphorylation state of key signalling molecules, which report the activation state of the pathways. In total, we have identified 20 new molecules that regulate the activity of one or more signalling pathways during early Xenopus development. This is the first time that such a functional screen has been performed, and the findings pave the way toward a more comprehensive understanding of the molecular mechanisms regulating the activity of important signalling pathways under normal and pathological conditions. 相似文献
942.
Nayeli Monterrosas-Brisson Mayra Zagal-Guzmán Alejandro Zamilpa Enrique Jiménez-Ferrer Margarita Avilés-Flores Macrina Fuentes-Mata Maribel Herrera-Ruiz 《化学与生物多样性》2021,18(3):e2000790
Argemone mexicana L. is a widely used plant in Mexican traditional medicine to treat inflammatory and nervous medical conditions. It has been subjected to several pharmacological and chemical studies in which acute anti-inflammatory activity is indicated. This work aimed at finding an extract and fraction with anti-inflammatory activity by means of 2-O-tetradecanoylphorbol-13-acetate (TPA)-induced auricular edema. Afterward, the extract and the fraction were tested on neuroinflammation caused by lipopolysaccharides (LPS). Treatments obtained from A. mexicana included the methanolic extract (AmMeOH), a fraction extracted with ethyl acetate (AmAcOEt), and four sub-fractions (AmF-1 to AmF-4), which were evaluated in auricular edema with the TPA assay. Both treatments with the most significant inhibitory effect were employed to test these in the LPS neuroinflammation model. AmAcOEt and AmF-3 induced a higher inhibition of edema (%), and both diminished ear inflammation when viewed under a microscope. These treatments also raised an increase in spleen, but not in brain of mice with neuroinflammation. They were able to decrease the concentration of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) in both organs. Furthermore, the accumulation of amyloid-β (Aβ) in hippocampus was not visible. AmF-3 contains the flavonoids isoquercetin, luteolin, and rutin, the former being the most concentrated. 相似文献
943.
The intrinsic rate of nitrification was observed in a batch reactor by eliminating external and internal diffusional resistances. The former were minimized by means of intense agitation, and the latter by mechanical rupture of the activated sludge flocs using high mixer rotational speeds. The optimum temperature and pH for the intrinsic nitrification rate were found to be 30–35°C and 8.0, respectively. Initial ammonium concentration was found to have a strong effect on the value of the kinetic parameters of the Michaelis–Menten rate expression at low ammonium levels. However, at high initial concentrations both parameters attained a constant maximum value that is independent of the initial substrate level. 相似文献
944.
945.
Carlo Polidori Cayetano Gutiérrez-Cánovas Enrique Sánchez José Tormos Leopoldo Castro David Sánchez-Fernández 《Ecological Entomology》2020,45(1):130-141
1. Climate change is expected to produce shifts in species distributions as well as behavioural, life-history, and/or morphological adaptations to find suitable conditions or cope with the altered environment. Most of our knowledge on this issue comes from studies on vertebrates, mainly endotherm species. However, it remains uncertain how small ectotherms, such as insects, respond to increased temperature. 2. This study tested whether climate change over the last 100 years (1904–2013) has affected morphological and functional traits in workers of the social wasp Dolichovespula sylvestris in the Iberian Peninsula. 3. Head width and forewing length, as well as body mass and wing area (assuming no change in shape), decreased over time and with increased mean annual temperature, even when controlling for geographical location and altitude. Interestingly, wing size decreased with a steeper slope compared with body size. If there is no change in wing shape, this would lead to an invariable wing loading (body mass:wing area ratio) over time, with potential consequences on flying ability of more recent (and thus smaller) wasp individuals. 4. These results suggest that recent climate change is leaving morphological signatures in social wasps, increasing the evidence for this phenomenon in insects. The data furthermore suggest that the known efficient thermoregulatory ability of social insect colonies may not successfully buffer the effect of global warming. 相似文献
946.
A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis 总被引:1,自引:0,他引:1
Enrique Meléndez-Hevia Patricia de Paz-Lugo Athel Cornish-Bowden María Luz Cárdenas 《Journal of biosciences》2009,34(6):853-872
In a previous paper, we pointed out that the capability to synthesize glycine from serine is constrained by the stoichiometry
of the glycine hydroxymethyltransferase reaction, which limits the amount of glycine produced to be no more than equimolar
with the amount of C 1 units produced. This constraint predicts a shortage of available glycine if there are no adequate compensating
processes. Here, we test this prediction by comparing all reported fluxes for the production and consumption of glycine in
a human adult. Detailed assessment of all possible sources of glycine shows that synthesis from serine accounts for more than
85% of the total, and that the amount of glycine available from synthesis, about 3 g/day, together with that available from
the diet, in the range 1.5–3.0 g/day, may fall significantly short of the amount needed for all metabolic uses, including
collagen synthesis by about 10 g per day for a 70 kg human. This result supports earlier suggestions in the literature that
glycine is a semi-essential amino acid and that it should be taken as a nutritional supplement to guarantee a healthy metabolism. 相似文献
947.
Junkal Garmendia Cristina Viadas Laura Calatayud Joshua Chang Mell Pau Martí-Lliteras Bego?a Euba Enrique Llobet Carmen Gil José Antonio Bengoechea Rosemary J. Redfield Josefina Li?ares 《PloS one》2014,9(5)
Nontypable Haemophilus influenzae (NTHi) has emerged as an important opportunistic pathogen causing infection in adults suffering obstructive lung diseases. Existing evidence associates chronic infection by NTHi to the progression of the chronic respiratory disease, but specific features of NTHi associated with persistence have not been comprehensively addressed. To provide clues about adaptive strategies adopted by NTHi during persistent infection, we compared sequential persistent isolates with newly acquired isolates in sputa from six patients with chronic obstructive lung disease. Pulse field gel electrophoresis (PFGE) identified three patients with consecutive persistent strains and three with new strains. Phenotypic characterisation included infection of respiratory epithelial cells, bacterial self-aggregation, biofilm formation and resistance to antimicrobial peptides (AMP). Persistent isolates differed from new strains in showing low epithelial adhesion and inability to form biofilms when grown under continuous-flow culture conditions in microfermenters. Self-aggregation clustered the strains by patient, not by persistence. Increasing resistance to AMPs was observed for each series of persistent isolates; this was not associated with lipooligosaccharide decoration with phosphorylcholine or with lipid A acylation. Variation was further analyzed for the series of three persistent isolates recovered from patient 1. These isolates displayed comparable growth rate, natural transformation frequency and murine pulmonary infection. Genome sequencing of these three isolates revealed sequential acquisition of single-nucleotide variants in the AMP permease sapC, the heme acquisition systems hgpB, hgpC, hup and hxuC, the 3-deoxy-D-manno-octulosonic acid kinase kdkA, the long-chain fatty acid transporter ompP1, and the phosphoribosylamine glycine ligase purD. Collectively, we frame a range of pathogenic traits and a repertoire of genetic variants in the context of persistent infection by NTHi. 相似文献
948.
Orlando Alva Rosa Nair Roa-Roco Ricardo Pérez-Díaz Mónica Yá?ez Jaime Tapia Yerko Moreno Simón Ruiz-Lara Enrique González 《PloS one》2015,10(10)
Parthenocarpic fruit development (PFD) reduces fruit yield and quality in grapevine. Parthenocarpic seedless berries arise from fruit set without effective fertilization due to defective pollen germination. PFD has been associated to micronutrient deficiency but the relation of this phenomenon with pollen polymorphism has not been reported before. In this work, six grapevine cultivars with different tendency for PFD and grown under micronutrient-sufficient conditions were analyzed to determine pollen structure and germination capability as well as PFD rates. Wide variation in non-germinative abnormal pollen was detected either among cultivars as well as for the same cultivar in different growing seasons. A straight correlation with PFD rates was found (R2 = 0.9896), suggesting that natural parthenocarpy is related to defective pollen development. Such relation was not observed when PFD was analyzed in grapevine plants exposed to exogenous gibberellin (GA) or abscissic acid (ABA) applications at pre-anthesis. Increase (GA treatment) or reduction (ABA treatment) in PFD rates without significative changes in abnormal pollen was determined. Although these plants were maintained at sufficient boron (B) condition, a down-regulation of the floral genes VvBOR3 and VvBOR4 together with a reduction of floral B content in GA-treated plants was established. These results suggest that impairment in B mobility to reproductive tissues and restriction of pollen tube growth could be involved in the GA-induced parthenocarpy. 相似文献
949.
950.
Jaime Feliu Antonieta Salud Maria J. Safont Carlos García-Girón Jorge Aparicio Ferran Losa Carlos Bosch Pilar Escudero Enrique Casado Monica Jorge Uriel Bohn Ramon Pérez-Carrión Alberto Carmona Ana B. Custodio Joan Maurel 《PloS one》2015,10(1)