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111.
112.
Kai T. Lohbeck Ulf Riebesell Sinéad Collins Thorsten B. H. Reusch 《Evolution; international journal of organic evolution》2013,67(7):1892-1900
Predicting the impacts of environmental change on marine organisms, food webs, and biogeochemical cycles presently relies almost exclusively on short‐term physiological studies, while the possibility of adaptive evolution is often ignored. Here, we assess adaptive evolution in the coccolithophore Emiliania huxleyi, a well‐established model species in biological oceanography, in response to ocean acidification. We previously demonstrated that this globally important marine phytoplankton species adapts within 500 generations to elevated CO2. After 750 and 1000 generations, no further fitness increase occurred, and we observed phenotypic convergence between replicate populations. We then exposed adapted populations to two novel environments to investigate whether or not the underlying basis for high CO2‐adaptation involves functional genetic divergence, assuming that different novel mutations become apparent via divergent pleiotropic effects. The novel environment “high light” did not reveal such genetic divergence whereas growth in a low‐salinity environment revealed strong pleiotropic effects in high CO2 adapted populations, indicating divergent genetic bases for adaptation to high CO2. This suggests that pleiotropy plays an important role in adaptation of natural E. huxleyi populations to ocean acidification. Our study highlights the potential mutual benefits for oceanography and evolutionary biology of using ecologically important marine phytoplankton for microbial evolution experiments. 相似文献
113.
114.
Tomá? Albrecht Oddmund Kleven Jakub Kreisinger Terje Laskemoen Taiwo C. Omotoriogun Ulf Ottosson Ji?í Reif Ond?ej Sedlá?ek David Ho?ák Raleigh J. Robertson Jan T. Lifjeld 《Proceedings. Biological sciences / The Royal Society》2013,280(1752)
Sperm competition represents an important component of post-copulatory sexual selection. It has been argued that the level of sperm competition declines in birds towards the equator. However, to date, sperm competition estimates have been available mainly for avian species inhabiting the northern temperate zone. Here we apply a novel approach, using the coefficient of between-male variation (CVbm) in sperm size as an index for sperm competition risk, in a comparative analysis of 31 Afrotropical and 99 northern temperate zone passerine species. We found no difference in sperm competition risk between the two groups, nor any relationship with migration distance. However, a multivariate model indicated that sperm competition risk was highest in species with a combination of low body mass and few eggs per clutch. The effect of clutch size was most pronounced in tropical species, which indicates that sperm competition risk in tropical and temperate species is differently associated with particular life-history traits. Although tropical species had lower sperm competition risk than temperate zone species for overlapping clutch sizes, the idea of a generally reduced risk of sperm competition in tropical birds was not supported by our analysis. 相似文献
115.
Andreas Stengel Tobias Hofmann Miriam Goebel-Stengel Vanessa Lembke Anne Ahnis Ulf Elbelt Nils W. G. Lambrecht Jürgen Ordemann Burghard F. Klapp Peter Kobelt 《Histochemistry and cell biology》2013,139(6):909-918
The orexigenic peptide ghrelin and the anorexigenic peptide nesfatin-1 are expressed by the same endocrine cell of the rat stomach, the X/A-like cell. However, data in humans are lacking, especially under conditions of obesity. We collected gastric tissue of obese patients undergoing sleeve gastrectomy and investigated the expression of nesfatin-1 and ghrelin in the gastric oxyntic mucosa by immunofluorescence. Nesfatin-1 immunoreactivity was detected in the human oxyntic mucosa in cells with an endocrine phenotype. A major portion of nesfatin-1 immunoreactive cells (78 %) co-localized with ghrelin indicating the occurrence in human X/A-like cells. In patients with very high body mass index (BMI 55–65 kg/m2), the number of nesfatin-1 immunoreactive cells/low-power field was significantly higher than in obese patients with lower BMI (40–50 kg/m2, 118 ± 10 vs. 82 ± 11, p < 0.05). On the other hand, the number of ghrelin immunoreactive cells was significantly reduced in obese patients with higher compared to lower BMI (96 ± 12 vs. 204 ± 21, p < 0.01). Also the ghrelin-acylating enzyme ghrelin-O-acyltransferase decreased with increasing BMI. In conclusion, nesfatin-1 immunoreactivity is also co-localized with ghrelin in human gastric X/A-like cells giving rise to a dual role of this cell type with differential effects on stimulation and inhibition of appetite dependent on the peptide released. The expression of these two peptides is differentially regulated under obese conditions with an increase of nesfatin-1 and a decrease of ghrelin immunoreactivity with rising BMI pointing towards an adaptive change of expression that may counteract further body weight increase. 相似文献
116.
Ulf W Liebal Thomas Millat Jon Marles-Wright Richard J Lewis Olaf Wolkenhauer 《BMC systems biology》2013,7(1):1-12
Background
The stressosome is a bacterial signalling complex that responds to environmental changes by initiating a protein partner switching cascade, which leads to the release of the alternative sigma factor, σB. Stress perception increases the phosphorylation of the stressosome sensor protein, RsbR, and the scaffold protein, RsbS, by the protein kinase, RsbT. Subsequent dissociation of RsbT from the stressosome activates the σB cascade. However, the sequence of physical events that occur in the stressosome during signal transduction is insufficiently understood.Results
Here, we use computational modelling to correlate the structure of the stressosome with the efficiency of the phosphorylation reactions that occur upon activation by stress. In our model, the phosphorylation of any stressosome protein is dependent upon its nearest neighbours and their phosphorylation status. We compare different hypotheses about stressosome activation and find that only the model representing the allosteric activation of the kinase RsbT, by phosphorylated RsbR, qualitatively reproduces the experimental data.Conclusions
Our simulations and the associated analysis of published data support the following hypotheses: (i) a simple Boolean model is capable of reproducing stressosome dynamics, (ii) different stressors induce identical stressosome activation patterns, and we also confirm that (i) phosphorylated RsbR activates RsbT, and (ii) the main purpose of RsbX is to dephosphorylate RsbS-P. 相似文献117.
Andrew J. Atkin Kirsten Corder Ulf Ekelund Katrien Wijndaele Simon J. Griffin Esther M. F. van Sluijs 《PloS one》2013,8(6)
Background
Understanding the determinants of sedentary time during childhood contributes to the development of effective intervention programmes.Purpose
To examine family and home-environmental determinants of 1-year change in objectively measured sedentary time after-school and at the weekend.Methods
Participants wore accelerometers at baseline and 1 year later. Longitudinal data for after-school and weekend analyses were available for 854 (41.5%male, mean±SD age 10.2±0.3years) and 718 (41.8%male, age 10.2±0.3years) participants. Information on 26 candidate determinants, including socioeconomic status (SES), availability of electronic media and parental rules for sedentary behaviours was self-reported by children or their parents at baseline. Change in the proportion of registered time spent sedentary was used as the outcome variable in multi-level linear regression models, adjusted for age, sex, body mass index and baseline sedentary time. Simple and multiple models were run and interactions with sex explored.Results
Children from higher socioeconomic status families exhibited greater increases in after-school (beta; 95% CI for change in % time spent sedentary 1.02; 0.37, 1.66) and weekend (1.42; 0.65, 2.18) sedentary time. Smaller increases in after-school sedentary time were observed in children with more siblings (−1.00; −1.69, −0.30), greater availability of electronic media (−0.81; −1.29, −0.33) and, for boys, more frequent family visits to the park (−1.89; −3.28, −0.51) and family participation in sport (−1.28; −2.54, −0.02). Greater maternal weekend screen-time (0.45; 0.08, 0.83) and, in girls, greater parental restriction on playing outside (0.91; 0.08, 1.74) were associated with larger increases in weekend sedentary time. The analytical sample was younger, more likely to be female, had lower BMI and was of higher SES than the original baseline sample.Conclusions
Intervention strategies aimed at reducing parents’ weekend screen-time, increasing family participation in sports or recreation (boys) and promoting freedom to play outside (girls) may contribute towards preventing the age-related increase in sedentary time. 相似文献118.
Catherine M. Phillips Audrey C. Tierney Pablo Perez‐Martinez Catherine Defoort Ellen E. Blaak Ingrid M. F. Gjelstad Jose Lopez‐Miranda Malgorzata Kiec‐Klimczak Malgorzata Malczewska‐Malec Christian A. Drevon Wendy Hall Julie A. Lovegrove Brita Karlstrom Ulf Risérus Helen M. Roche 《Obesity (Silver Spring, Md.)》2013,21(1):E154-E161
Objective:
Obesity is a key factor in the development of the metabolic syndrome (MetS), which is associated with increased cardiometabolic risk. We investigated whether obesity classification by BMI and body fat percentage (BF%) influences cardiometabolic profile and dietary responsiveness in 486 MetS subjects (LIPGENE dietary intervention study).Design and Methods:
Anthropometric measures, markers of inflammation and glucose metabolism, lipid profiles, adhesion molecules, and hemostatic factors were determined at baseline and after 12 weeks of four dietary interventions (high saturated fat (SFA), high monounsaturated fat (MUFA), and two low fat high complex carbohydrate (LFHCC) diets, one supplemented with long chain n‐3 polyunsaturated fatty acids (LC n‐3 PUFAs)).Results:
About 39 and 87% of subjects classified as normal and overweight by BMI were obese according to their BF%. Individuals classified as obese by BMI (≥30 kg/m2) and BF% (≥25% (men) and ≥35% (women)) (OO, n = 284) had larger waist and hip measurements, higher BMI and were heavier (P < 0.001) than those classified as nonobese by BMI but obese by BF% (NOO, n = 92). OO individuals displayed a more proinflammatory (higher C reactive protein (CRP) and leptin), prothrombotic (higher plasminogen activator inhibitor‐1 (PAI‐1)), proatherogenic (higher leptin/adiponectin ratio) and more insulin resistant (higher HOMA‐IR) metabolic profile relative to the NOO group (P < 0.001). Interestingly, tumor necrosis factor‐α (TNF‐α) concentrations were lower post‐intervention in NOO individuals compared with OO subjects (P < 0.001).Conclusions:
In conclusion, assessing BF% and BMI as part of a metabotype may help to identify individuals at greater cardiometabolic risk than BMI alone. 相似文献119.
Background
Disseminated intravascular coagulopathy (DIC) relates to the consumption of coagulation factors and platelets with bleeding and micro thrombosis events.Aim
The aim of this study was to compare haemostasis parameters in critically ill patients with DIC versus patients without DIC, and in survivors versus non-survivors over time. Correlations between the DIC-score, the degree of organ failure and the haemostasis were assessed.Method
Patients admitted to the intensive care unit with a condition known to be associated with DIC and with an expected length of stay of >3 days were included. Routine laboratory tests, prothrombin time, activated partial thromboplastin time, platelet count, fibrinogen concentration and D-dimer were measured. Coagulation and platelet function were assessed with two point-of-care devices; Multiplate and ROTEM. DIC scores were calculated according to the International Society on Thrombosis and Haemostasis and Japanese Association for Acute Medicine.Results
Blood was sampled on days 0–1, 2–3 and 4–10 from 136 patients with mixed diagnoses during 290 sampling events. The point-of-care assays indicated a hypocoagulative response (decreased platelet aggregation and reduced clot strength) in patients with DIC and, over time, in non-survivors compared to survivors. Patients with DIC as well as non-survivors had decreased fibrinolysis as shown by ROTEM. DIC scores were higher in non-survivors than in survivors.Conclusions
Patients with DIC displayed signs of a hypocoagulative response and impaired fibrinolysis, which was also evident over time in non-survivors. Patients with DIC had a higher mortality rate than non-DIC patients, and DIC scores were higher in non-survivors than in survivors. 相似文献120.
Teresa Kauke Sandra Klimaschewski Ulf Schoenermarck Michael Fischereder Andrea Dick Markus Guba Manfred Stangl Jens Werner Bruno Meiser Antje Habicht 《PloS one》2016,11(1)