全文获取类型
收费全文 | 2637篇 |
免费 | 288篇 |
出版年
2022年 | 15篇 |
2021年 | 26篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 30篇 |
2017年 | 35篇 |
2016年 | 58篇 |
2015年 | 81篇 |
2014年 | 94篇 |
2013年 | 126篇 |
2012年 | 137篇 |
2011年 | 153篇 |
2010年 | 102篇 |
2009年 | 90篇 |
2008年 | 124篇 |
2007年 | 136篇 |
2006年 | 105篇 |
2005年 | 105篇 |
2004年 | 102篇 |
2003年 | 112篇 |
2002年 | 90篇 |
2001年 | 80篇 |
2000年 | 107篇 |
1999年 | 88篇 |
1998年 | 32篇 |
1997年 | 45篇 |
1996年 | 37篇 |
1995年 | 38篇 |
1994年 | 38篇 |
1993年 | 37篇 |
1992年 | 58篇 |
1991年 | 57篇 |
1990年 | 60篇 |
1989年 | 47篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 48篇 |
1985年 | 34篇 |
1984年 | 17篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1979年 | 21篇 |
1978年 | 16篇 |
1976年 | 18篇 |
1975年 | 14篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1972年 | 21篇 |
1970年 | 15篇 |
排序方式: 共有2925条查询结果,搜索用时 125 毫秒
971.
Anne Louise Bischoff Nilofar Vahman F?lsgaard Charlotte Giwercman Carson Jakob Stokholm Louise Pedersen Maria Holmberg Amalie Bisgaard Sune Birch Theodore F. Tsai Hans Bisgaard 《PloS one》2013,8(4)
Background
Pregnant women were suspected to be at particular risk when H1N1pnd09 influenza became pandemic in 2009. Our primary objective was to compare the immune responses conferred by MF59®-adjuvanted vaccine (Focetria®) in H1N1pnd09-naïve pregnant and non-pregnant women. The secondary aims were to compare influences of dose and adjuvant on the immune response.Methods
The study was nested in the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC2010) pregnancy cohort in 2009-2010 and conducted as a single-blinded block-randomised [1∶1∶1] controlled clinical trial in pregnant women after gestational week 20: (1) 7.5 µg H1N1pnd09 antigen with MF59-adjuvant (Pa7.5 µg); (2) 3.75 µg antigen half MF59-adjuvanted (Pa3.75 µg); (3) 15 µg antigen unadjuvanted (P15 µg); and in non-pregnant women receiving (4) 7.5 µg antigen full adjuvanted (NPa7.5 µg). Blood samples were collected at baseline, 3 weeks, 3 and 10 months after vaccination, adverse events were recorded prospectively.Results
58 pregnant women were allocated to Pa7.5 µg and 149 non-pregnant women were recruited to NPa7.5 µg. The sero-conversion rate was significantly increased in non-pregnant (NPa7.5 µg) compared with pregnant (Pa7.5 µg) women (OR = 2.48 [1.03–5.95], p = 0.04) and geometric mean titers trended towards being higher, but this difference was not statistically significant (ratio 1.27 [0.85–1.93], p = 0.23). The significant titer increase rate showed no difference between pregnant (Pa7.5 µg) and non-pregnant (NPa7.5 µg) groups (OR = 0.49 [0.13–1.85], p = 0.29).Conclusion
Our study suggests the immune response to the 7.5 µg MF59-adjuvanted Focetria® H1N1pnd09 vaccine in pregnant women may be diminished compared with non-pregnant women.Trial Registration
ClinicalTrials.gov . NCT01012557相似文献972.
973.
974.
Ci Song Nancy L. Pedersen Chandra A. Reynolds Maria Sabater-Lleal Stavroula Kanoni Christina Willenborg the CARDIoGRAMplusCD Consortium Ann-Christine Syv?nen Hugh Watkins Anders Hamsten Jonathan A. Prince Erik Ingelsson 《PloS one》2013,8(3)
Background
Circulating lipids levels, as well as several familial lipid metabolism disorders, are strongly associated with initiation and progression of atherosclerosis and incidence of myocardial infarction (MI).Objectives
We hypothesized that genetic variants associated with circulating lipid levels would also be associated with MI incidence, and have tested this in three independent samples.Setting and Subjects
Using age- and sex-adjusted additive genetic models, we analyzed 554 single nucleotide polymorphisms (SNPs) in 41 candidate gene regions proposed to be involved in lipid-related pathways potentially predisposing to incidence of MI in 2,602 participants of the Swedish Twin Register (STR; 57% women). All associations with nominal P<0.01 were further investigated in the Uppsala Longitudinal Study of Adult Men (ULSAM; N = 1,142).Results
In the present study, we report associations of lipid-related SNPs with incident MI in two community-based longitudinal studies with in silico replication in a meta-analysis of genome-wide association studies. Overall, there were 9 SNPs in STR with nominal P-value <0.01 that were successfully genotyped in ULSAM. rs4149313 located in ABCA1 was associated with MI incidence in both longitudinal study samples with nominal significance (hazard ratio, 1.36 and 1.40; P-value, 0.004 and 0.015 in STR and ULSAM, respectively). In silico replication supported the association of rs4149313 with coronary artery disease in an independent meta-analysis including 173,975 individuals of European descent from the CARDIoGRAMplusC4D consortium (odds ratio, 1.03; P-value, 0.048).Conclusions
rs4149313 is one of the few amino acid changing variants in ABCA1 known to associate with reduced cholesterol efflux. Our results are suggestive of a weak association between this variant and the development of atherosclerosis and MI. 相似文献975.
Hall Schartum-Hansen Per M. Ueland Eva R. Pedersen Klaus Meyer Marta Ebbing ?yvind Bleie Gard F. T. Svingen Reinhard Seifert Bj?rn E. Vikse Ottar Nyg?rd 《PloS one》2013,8(8)
Abnormal urinary excretion of betaine has been demonstrated in patients with diabetes or metabolic syndrome. We aimed to identify the main predictors of excretion in cardiovascular patients and to make initial assessment of its feasibility as a risk marker of future diabetes development. We used data from 2396 patients participating in the Western Norway B-vitamin Intervention Trial, who delivered urine and blood samples at baseline, and in the majority at two visits during follow-up of median 39 months. Betaine in urine and plasma were measured by liquid-chromatography-tandem mass spectrometry. The strongest determinants of urinary betaine excretion by multiple regression were diabetes mellitus, age and estimated glomerular filtration rate; all p<0.001. Patients with diabetes mellitus (n = 264) had a median excretion more than three times higher than those without. We found a distinct non-linear association between urinary betaine excretion and glycated hemoglobin, with a break-point at 6.5%, and glycated hemoglobin was the strongest determinant of betaine excretion in patients with diabetes mellitus. The discriminatory power for diabetes mellitus corresponded to an area under the curve by receiver-operating characteristics of 0.82, and betaine excretion had a coefficient of reliability of 0.73. We also found a significant, independent log-linear relation between baseline betaine excretion and the risk of developing new diabetes during follow-up. The good discriminatory power for diabetes, high test-retest stability and independent association with future risk of new diabetes should motivate further investigation on the role of betaine excretion in risk assessment and long-term follow-up of diabetes mellitus. 相似文献
976.
977.
An elachistacean epiphyte, Neoleptonema yongpilii E.-Y. Lee & I.K. Lee, gen. et sp. nov., is reported from Korean coasts. The plants are distinguished by having unbranched assimilatory filaments with intercalary plurilocular sporangia as well as lateral plurilocular sporangia from the cortex. The new genus differs from the genera Leptonematella P. Silva and Halothrix Reinke by having pod-shaped plurilocular sporangia on the medulla, and from Elachista Duby and Proselachista Y.P. Lee & Garbary by having intercalary plurilocular sporangia and a poorly developed medulla. The phylogenetic relationships of Neoleptonema yongpilii were inferred from the spacer sequences between the genes coding for the large and small subunits of the RuBisCO gene. The new genus is a member of a poorly resolved clade consisting of several genera within the Elachistaceae, within which it is more closely related to Halothrix and Elachista nipponica than to Leptonematella. 相似文献
978.
Henrik Ærenlund Pedersen 《Nordic Journal of Botany》2011,29(2):182-183
It is argued that an alleged lectotype of the name Epipactis leptochila (designated in 1981) is actually a neotype, as the published plate in question did not appear in print until 14 years after the protologue. A herbarium specimen at BM represents original material that was used by Godfery when describing the E. leptochila, and in all probability the same is true for the original watercolour painting (now deposited at the Natural History Museum, London) from which the published plate was eventually reproduced. Therefore, a part of the herbarium specimen is designated as lectotype. 相似文献
979.
Broch-Lips M de Paoli F Pedersen TH Overgaard K Nielsen OB 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,111(1):212-220
During intense exercise, efflux of K(+) from working muscles increases extracellular K(+) ([K(+)](o)) to levels that can compromise muscle excitability and hence cause fatigue. In this context, the reduction in the exercise-induced elevation of [K(+)](o) observed after training in humans is suggested to contribute to the increased performance after training. Although a similar effect could be obtained by an increase in the tolerance of muscle to elevated [K(+)](o), this possibility has not been investigated. To examine this, isolated soleus muscles from sedentary (sedentary) rats and from rats that had voluntarily covered 13.1 ± 0.7 km/day in an unloaded running wheel for 8 wk (active) were compared. In muscles from active rats, the loss of force induced by exposure to an elevated [K(+)](o) of 9 mM was 42% lower than in muscles from sedentary rats (P < 0.001). This apparent increase in K(+) tolerance in active rats was associated with an increased excitability as evident from a 33% reduction in the electrical current needed to excite individual muscle fibers (P < 0.0009). Moreover, muscles from active rats had lower Cl(-) conductance, higher maximal rate of rise of single-fiber action potentials (AP), and higher Na(+)/K(+) pump content. When stimulated intermittently at 6.5 mM K(+), muscles from active rats displayed better endurance than muscles from sedentary rats, whereas no difference was found when the muscles were stimulated continuously at 30 or 120 Hz. We conclude that voluntary running increases muscle excitability, leading to improved tolerance to elevated [K(+)](o). 相似文献
980.