全文获取类型
收费全文 | 3312篇 |
免费 | 254篇 |
出版年
2023年 | 25篇 |
2022年 | 8篇 |
2021年 | 75篇 |
2020年 | 57篇 |
2019年 | 81篇 |
2018年 | 97篇 |
2017年 | 76篇 |
2016年 | 107篇 |
2015年 | 190篇 |
2014年 | 222篇 |
2013年 | 225篇 |
2012年 | 294篇 |
2011年 | 239篇 |
2010年 | 141篇 |
2009年 | 149篇 |
2008年 | 170篇 |
2007年 | 146篇 |
2006年 | 127篇 |
2005年 | 119篇 |
2004年 | 122篇 |
2003年 | 108篇 |
2002年 | 113篇 |
2001年 | 40篇 |
2000年 | 26篇 |
1999年 | 34篇 |
1998年 | 22篇 |
1997年 | 14篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 24篇 |
1987年 | 14篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1924年 | 8篇 |
排序方式: 共有3566条查询结果,搜索用时 15 毫秒
1.
Felix Schiele John Park Norbert Redemann Gerd Luippold Herbert Nar 《Journal of molecular biology》2014
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with autosomal dominant hypercholesterolemia, a state of elevated levels of LDL (low-density lipoprotein) cholesterol. Autosomal dominant hypercholesterolemia can result in severe implications such as stroke and coronary heart disease. The inhibition of PCSK9 function by therapeutic antibodies that block interaction of PCSK9 with the epidermal growth factor-like repeat A domain of LDL receptor (LDLR) was shown to successfully lower LDL cholesterol levels in clinical studies. Here we present data on the identification, structural and biophysical characterization and in vitro and in vivo pharmacology of a PCSK9 antibody (mAb1). The X-ray structure shows that mAb1 binds the module 1 of the C-terminal domain (CTD) of PCSK9. It blocks access to an area bearing several naturally occurring gain-of-function and loss-of-function mutations. Although the antibody does not inhibit binding of PCSK9 to epidermal growth factor-like repeat A, it partially reverses PCSK9-induced reduction of the LDLR and LDL cholesterol uptake in a cellular assay. mAb1 is also effective in lowering serum levels of LDL cholesterol in cynomolgus monkeys in vivo. Complete loss of PCSK9 is associated with insufficient liver regeneration and increased risk of hepatitis C infections. Blocking of the CTD is sufficient to partially inhibit PCSK9 function. Antibodies binding the CTD of PCSK9 may thus be advantageous in patients that do not tolerate complete inhibition of PCSK9. 相似文献
2.
3.
Carlos Fernández-Palomeque Andres Grau Joan Perelló Pilar Sanchis Bernat Isern Rafel M. Prieto Antonia Costa-Bauzá Onofre J. Caldés Oriol Bonnin Ana Garcia-Raja Armando Bethencourt Felix Grases 《PloS one》2015,10(8)
Pathological calcification generally consists of the formation of solid deposits of hydroxyapatite (calcium phosphate) in soft tissues. Supersaturation is the thermodynamic driving force for crystallization, so it is believed that higher blood levels of calcium and phosphate increase the risk of cardiovascular calcification. However several factors can promote or inhibit the natural process of pathological calcification. This cross-sectional study evaluated the relationship between physiological levels of urinary phytate and heart valve calcification in a population of elderly out subjects. A population of 188 elderly subjects (mean age: 68 years) was studied. Valve calcification was measured by echocardiography. Phytate determination was performed from a urine sample and data on blood chemistry, end-systolic volume, concomitant diseases, cardiovascular risk factors, medication usage and food were obtained. The study population was classified in three tertiles according to level of urinary phytate: low (<0.610 μM), intermediate (0.61–1.21 μM), and high (>1.21 μM). Subjects with higher levels of urinary phytate had less mitral annulus calcification and were less likely to have diabetes and hypercholesterolemia. In the multivariate analysis, age, serum phosphorous, leukocytes total count and urinary phytate excretion appeared as independent factors predictive of presence of mitral annulus calcification. There was an inverse correlation between urinary phytate content and mitral annulus calcification in our population of elderly out subjects. These results suggest that consumption of phytate-rich foods may help to prevent cardiovascular calcification evolution. 相似文献
4.
Flávia Correa Raffaini Alice Ramos Freitas Thalisson Saymo Oliveira Silva Tarsis Cavagioni Jessica Felix Oliveira Rubens Ferreira Albuquerque Junior 《Biofouling》2018,34(2):173-182
This cross-sectional study aimed to identify and quantify up to 42 target species colonizing the early biofilm of dental implants restored with titanium or zirconia abutments. A total of 720 samples from 20 healthy individuals were investigated. Biofilm samples were collected from the peri-implant sulci, inner parts of implants, abutment surfaces and prosthetic crowns over a functioning period of 30 days. Checkerboard DNA–DNA hybridization was used for microbial detection and quantitation. Clinical characteristics (probing depth, bleeding on probing, clinical attachment level and marginal bone loss) were also investigated during the monitoring period. Genome counts were low at the implant loading time point for both the abutment materials, and increased over time. Both the titanium and the zirconia groups presented similar microbial counts and diversity over time, and the microbiota was very similar to that colonizing the remaining teeth. Clinical findings were consistent with a healthy condition with no significant difference regarding marginal bone loss between the two materials. 相似文献
5.
6.
Development of genic cleavage markers in association with seed glucosinolate content in canola 总被引:1,自引:0,他引:1
7.
Background
Anesthetic administration is increasingly guided by electroencephalography (EEG)-based monitoring, such as the bispectral index (BIS). However, during cardiopulmonary bypass (CPB), factors other than the administered hypnotic agents may influence EEG signals, and their effects on BIS values are unknown.Methods
This report is a secondary analysis of data from a prospective, controlled interventional study comparing the effect of sevoflurane administration guided by BIS monitoring (group SevoBIS) and constant administration of sevoflurane (group Sevo1.8Vol%) during CPB. Sevoflurane plasma concentration (SPC) was measured using gas chromatography. The relationships of BIS to SPC, CPB pump flow, arterial pressure, hematocrit, temperature, time on CPB, and patient characteristics were analysed.Results
No association was observed between BIS values and SPC in group SevoBIS. In group Sevo1.8Vol%, a 40 μg ml-1 increase in SPC, which encompassed the entire range of observed values of the SPC in this analysis, was associated with a decrease of 3.6 (95% confidence interval (CI): 1.1–6.1) in BIS values (p = 0.005). Each increase in CPB time of 10 minutes was associated with an increase in BIS values of 0.25 (95%CI: 0.11–0.39, p<0.001). Path analysis revealed that the BIS values of SevoBIS patients were 5.3 (95%CI: 3.2–7.5) units higher than those of Sevo1.8Vol% patients (p<0.001), which was the strongest effect on BIS values. Path analysis revealed a slope of 0.5 (95%CI: 0.3–0.7) BIS units per 1°C body temperature (p<0.001).Conclusion
BIS monitoring is insensitive to clinically relevant changes in SPC in individual patients during CPB. 相似文献8.
Felix E.G. Beaudry Spencer C.H. Barrett Stephen I. Wright 《Evolution; international journal of organic evolution》2020,74(2):256-269
Empirical evidence from several animal groups suggests sex chromosomes disproportionately contribute to reproductive isolation. This effect may be enhanced when sex chromosomes are associated with turnover of sex determination systems resulting from structural rearrangements to the chromosomes. We investigated these predictions in the dioecious plant Rumex hastatulus, which is composed of populations of two different sex chromosome cytotypes caused by an X-autosome fusion. Using population genomic analyses, we investigated the demographic history of R. hastatulus and explored the contributions of ancestral and neo-sex chromosomes to population genetic divergence. Our study revealed that the cytotypes represent genetically divergent populations with evidence for historical but not contemporary gene flow between them. In agreement with classical predictions, we found that the ancestral X chromosome was disproportionately divergent compared with the rest of the genome. Excess differentiation was also observed on the Y chromosome, even when we used measures of differentiation that control for differences in effective population size. Our estimates of the timing of the origin of neo-sex chromosomes in R. hastatulus are coincident with cessation of gene flow, suggesting that the chromosomal fusion event that gave rise to the origin of the XYY cytotype may have also contributed to reproductive isolation. 相似文献
9.
10.