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981.
Düsman E Berti AP Mariucci RG Lopes NB Vicentini VE 《Radiation and environmental biophysics》2011,50(4):579-584
Iodine-131 (131I) is a radioisotope used for the diagnosis and treatment of thyroidal disorders such as hyperthyroidism and cancer. During
its decay, 131I emits beta particles and gamma rays; its physical half-life is 8 days, and it is accumulated preferentially in the thyroid
tissue. This study aimed to evaluate the cytotoxicity and mutagenicity of diagnostic and therapeutic doses of 131I using bone marrow cells of rats treated in vivo in a test system with a single dose by gavage. Concentrations of 5, 25,
50 and 250 μCi in 1 ml of water were used, and after 24 h, the animals were killed. Also, a concentration of 25 μCi/ml of
water was used, and the animals were killed after 5 days. The results showed that no concentration of 131I was cytotoxic and that all concentrations were mutagenic. As a result, there was no statistically significant difference
detected by the χ2 test in the induction of chromosomal aberrations between the different doses. Thus, the present study demonstrated a significant
increase in chromosomal aberration in bone marrow cells exposed to 131I regardless of the dose or the treatment time. 相似文献
982.
Gonçalves P Gregório I Martel F 《American journal of physiology. Cell physiology》2011,301(5):C984-C994
Colorectal cancer is one of the most common cancers worldwide. Butyrate (BT) plays a key role in colonic epithelium homeostasis. The aim of this work was to investigate the possibility of BT being transported by P-glycoprotein (MDR1), multidrug resistance proteins (MRPs), or breast cancer resistance protein (BCRP). Uptake and efflux of (14)C-BT and (3)H-folic acid were measured in Caco-2, IEC-6, and MDA-MB-231 cell lines. mRNA expression of BCRP was detected by RT-PCR. Cell viability, proliferation, and differentiation were quantified with the lactate dehydrogenase, sulforhodamine B, and alkaline phosphatase activity assays, respectively. In both IEC-6 cells and Caco-2 cells, no evidence was found for the involvement of either MDR1 or MRPs in (14)C-BT efflux from the cells. In contrast, several lines of evidence support the conclusion that BT is a substrate of both rat and human BCRP. Indeed, BCRP inhibitors reduced (14)C-BT efflux in IEC-6 cells, both BT and BCRP inhibitors significantly decreased the efflux of the known BCRP substrate (3)H-folic acid in IEC-6 cells, and BCRP inhibitors reduced (14)C-BT efflux in the BCRP-expressing MDA-MB-231 cell line. In IEC-6 cells, combination of BT with a BCRP inhibitor significantly potentiated the effect of BT on cell proliferation. The results of this study, showing for the first time that BT is a BCRP substrate, are very important in the context of the high levels of BCRP expression in the human colon and the anticarcinogenic and anti-inflammatory role of BT at that level. So, interaction of BT with BCRP and with other BCRP substrates/inhibitors is clearly of major importance. 相似文献
983.
Seminotti B Fernandes CG Leipnitz G Amaral AU Zanatta A Wajner M 《Neurochemical research》2011,36(2):205-214
Lysine (Lys) accumulation in tissues and biological fluids is the biochemical hallmark of patients affected by familial hyperlysinemia
(FH) and other inherited metabolic disorders. In the present study we investigated the effects of acute administration of
Lys on relevant parameters of energy metabolism and oxidative stress in striatum of young rats. We verified that Lys in vivo
intrastriatal injection did not change the citric acid cycle function and creatine kinase activity, but, in contrast, significantly
inhibited synaptic Na+,K+-ATPase activity in striatum prepared 2 and 12 h after injection. Moreover, Lys induced lipid peroxidation and diminished
the concentrations of glutathione 2 h after injection. These effects were prevented by the antioxidant scavengers melatonin
and the combination of α-tocopherol and ascorbic acid. Lys also inhibited glutathione peroxidase activity 12 h after injection.
Therefore it is assumed that inhibition of synaptic Na+,K+-ATPase and oxidative damage caused by brain Lys accumulation may possibly contribute to the neurological manifestations of
FH and other neurometabolic conditions with high concentrations of this amino acid. 相似文献
984.
Renata Stolf-Moreira Eliana G. M. Lemos L��cia Carareto-Alves Jackson Marcondes Selma S. Pereira Amanda A. P. Rolla Rodrigo M. Pereira Norman Neumaier Eliseu Binneck Ricardo V. Abdelnoor Maria C. N. de Oliveira Francismar C. Marcelino Jos�� R. B. Farias Alexandre L. Nepomuceno 《Plant Molecular Biology Reporter》2011,29(1):19-34
985.
Branco AT Dos Santos Ferreira B Lourenço GF Lopes Marques VC Tavares Machado OL Pereira MG Aquino Almeida JC de Souza Filho GA 《Protein and peptide letters》2011,18(7):651-657
β-1,3-glucanases are found in organisms as diverse as plants, animals, bacteria and fungi. In plants, such enzymes are not only associated with defense mechanisms against pathogens, but also play critical roles in physiological and developmental processes. Here we identified a new β-1,3-glucanase in maize seeds, and named it ZmGlucA. Sequence analysis revealed that ZmGlucA belongs to the class A of β-1,3-glucanase, a class related to defense and physiological processes in plants. mRNA and protein assays showed that zmGlucA is expressed exclusively in seeds, and it is differentially regulated during seed development. Additionally, zmGlucA expression is strongly induced in seeds of the mutant dek 827Kpro1, which is defective for embryo and endosperm development. Our data support the idea that ZmGlucA protein is relevant to seed development. 相似文献
986.
Renato S. Gonçalves Patrícia V. Abdelnur Vanessa G. Santos Rosineide C. Simas Marcos N. Eberlin Alviclér Magalhães Eduardo R. Pérez González 《Amino acids》2011,40(1):197-204
Abstract
Potentially bioactive N-(aminoalkyl)lactamic amino acids and esters were synthesized in satisfactory to good yields by SNAr reactions of aromatic acids with N-(3-aminopropyl)lactams followed by esterification with tertiary amino alcohols. The addition–elimination SNAr mechanism was confirmed by NMR and MS measurements. 相似文献987.
P. M. Paes de Sousa D. Rodrigues C. G. Timóteo M. L. Simões Gonçalves G. W. Pettigrew I. Moura J. J. G. Moura M. M. Correia dos Santos 《Journal of biological inorganic chemistry》2011,16(6):881-888
The activation mechanism of Pseudomonas stutzeri cytochrome c peroxidase (CCP) was probed through the mediated electrochemical catalysis by its physiological electron donor, P. stutzeri cytochrome c-551. A comparative study was carried out, by performing assays with the enzyme in the resting oxidized state as well as in
the mixed-valence activated form, using cyclic voltammetry and a pyrolytic graphite membrane electrode. In the presence of
both the enzyme and hydrogen peroxide, the peak-like signal of cytochrome c-551 is converted into a sigmoidal wave form characteristic of an
\textE\textr \textC\texti¢ {\text{E}}_{\text{r}} {\text{C}}_{\text{i}}^{\prime } catalytic mechanism. An intermolecular electron transfer rate constant of (4 ± 1) × 105 M−1 s−1 was estimated for both forms of the enzyme, as well as a similar Michaelis–Menten constant. These results show that neither
the intermolecular electron transfer nor the catalytic activity is kinetically controlled by the activation mechanism of CCP
in the case of the P. stutzeri enzyme. Direct enzyme catalysis using protein film voltammetry was unsuccessful for the analysis of the activation mechanism,
since P. stutzeri CCP undergoes an undesirable interaction with the pyrolytic graphite surface. This interaction, previously reported for the
Paracoccus pantotrophus CCP, induces the formation of a non-native conformation state of the electron-transferring haem, which has a redox potential
200 mV lower than that of the native state and maintains peroxidatic activity. 相似文献
988.
Montenegro MF Amaral JH Pinheiro LC Sakamoto EK Ferreira GC Reis RI Marçal DM Pereira RP Tanus-Santos JE 《Free radical biology & medicine》2011,51(1):144-152
Dietary nitrite and nitrate are important sources of nitric oxide (NO). However, the use of nitrite as an antihypertensive drug may be limited by increased oxidative stress associated with hypertension. We evaluated the antihypertensive effects of sodium nitrite given in drinking water for 4 weeks in two-kidney one-clip (2K1C) hypertensive rats and the effects induced by nitrite on NO bioavailability and oxidative stress. We found that, even under the increased oxidative stress conditions present in 2K1C hypertension, nitrite reduced systolic blood pressure in a dose-dependent manner. Whereas treatment with nitrite did not significantly change plasma nitrite concentrations in 2K1C rats, it increased plasma nitrate levels significantly. Surprisingly, nitrite treatment exerted antioxidant effects in both hypertensive and sham-normotensive control rats. A series of in vitro experiments was carried out to show that the antioxidant effects induced by nitrite do not involve direct antioxidant effects or xanthine oxidase activity inhibition. Conversely, nitrite decreased vascular NADPH oxidase activity. Taken together, our results show for the first time that nitrite has antihypertensive effects in 2K1C hypertensive rats, which may be due to its antioxidant properties resulting from vascular NADPH oxidase activity inhibition. 相似文献
989.
Long-range ozone transport and its impact on respiratory and cardiovascular health in the north of Portugal 总被引:2,自引:0,他引:2
Jezabel M. Azevedo Fabio L. T. Gonçalves Maria de Fátima Andrade 《International journal of biometeorology》2011,55(2):187-202
Ozone dynamics depend on meteorological characteristics such as wind, radiation, sunshine, air temperature and precipitation.
The aim of this study was to determine ozone trajectories along the northern coast of Portugal during the summer months of
2005, when there was a spate of forest fires in the region, evaluating their impact on respiratory and cardiovascular health
in the greater metropolitan area of Porto. We investigated the following diseases, as coded in the ninth revision of the International
Classification of Diseases: hypertensive disease (codes 401–405); ischemic heart disease (codes 410–414); other cardiac diseases,
including heart failure (codes 426–428); chronic obstructive pulmonary disease and allied conditions, including bronchitis
and asthma (codes 490–496); and pneumoconiosis and other lung diseases due to external agents (codes 500–507). We evaluated
ozone data from air quality monitoring stations in the study area, together with data collected through HYbrid Single-Particle
Lagrangian Integrated Trajectory (HYSPLIT) model analysis of air mass circulation and synoptic-scale zonal wind from National
Centers for Environmental Prediction data. High ozone levels in rural areas were attributed to the dispersion of pollutants
induced by local circulation, as well as by mesoscale and synoptic scale processes. The fires of 2005 increased the levels
of pollutants resulting from the direct emission of gases and particles into the atmosphere, especially when there were incoming
frontal systems. For the meteorological case studies analyzed, peaks in ozone concentration were positively associated with
higher rates of hospital admissions for cardiovascular diseases, although there were no significant associations between ozone
peaks and admissions for respiratory diseases. 相似文献
990.
Di Cairano ES Davalli AM Perego L Sala S Sacchi VF La Rosa S Finzi G Placidi C Capella C Conti P Centonze VE Casiraghi F Bertuzzi F Folli F Perego C 《The Journal of biological chemistry》2011,286(16):14007-14018
Glutamate is the major excitatory neurotransmitter of the central nervous system (CNS) and may induce cytotoxicity through persistent activation of glutamate receptors and oxidative stress. Its extracellular concentration is maintained at physiological concentrations by high affinity glutamate transporters of the solute carrier 1 family (SLC1). Glutamate is also present in islet of Langerhans where it is secreted by the α-cells and acts as a signaling molecule to modulate hormone secretion. Whether glutamate plays a role in islet cell viability is presently unknown. We demonstrate that chronic exposure to glutamate exerts a cytotoxic effect in clonal β-cell lines and human islet β-cells but not in α-cells. In human islets, glutamate-induced β-cell cytotoxicity was associated with increased oxidative stress and led to apoptosis and autophagy. We also provide evidence that the key regulator of extracellular islet glutamate concentration is the glial glutamate transporter 1 (GLT1). GLT1 localizes to the plasma membrane of β-cells, modulates hormone secretion, and prevents glutamate-induced cytotoxicity as shown by the fact that its down-regulation induced β-cell death, whereas GLT1 up-regulation promoted β-cell survival. In conclusion, the present study identifies GLT1 as a new player in glutamate homeostasis and signaling in the islet of Langerhans and demonstrates that β-cells critically depend on its activity to control extracellular glutamate levels and cellular integrity. 相似文献