全文获取类型
收费全文 | 4643篇 |
免费 | 403篇 |
国内免费 | 1篇 |
出版年
2023年 | 21篇 |
2022年 | 28篇 |
2021年 | 66篇 |
2020年 | 44篇 |
2019年 | 46篇 |
2018年 | 90篇 |
2017年 | 66篇 |
2016年 | 98篇 |
2015年 | 192篇 |
2014年 | 231篇 |
2013年 | 229篇 |
2012年 | 332篇 |
2011年 | 281篇 |
2010年 | 195篇 |
2009年 | 171篇 |
2008年 | 242篇 |
2007年 | 264篇 |
2006年 | 232篇 |
2005年 | 238篇 |
2004年 | 192篇 |
2003年 | 219篇 |
2002年 | 191篇 |
2001年 | 68篇 |
2000年 | 49篇 |
1999年 | 50篇 |
1998年 | 54篇 |
1997年 | 45篇 |
1996年 | 39篇 |
1995年 | 38篇 |
1994年 | 29篇 |
1993年 | 30篇 |
1992年 | 34篇 |
1991年 | 50篇 |
1990年 | 58篇 |
1989年 | 50篇 |
1988年 | 46篇 |
1987年 | 40篇 |
1986年 | 31篇 |
1985年 | 25篇 |
1984年 | 34篇 |
1983年 | 25篇 |
1982年 | 31篇 |
1981年 | 32篇 |
1980年 | 26篇 |
1978年 | 22篇 |
1977年 | 21篇 |
1975年 | 20篇 |
1974年 | 20篇 |
1973年 | 24篇 |
1967年 | 21篇 |
排序方式: 共有5047条查询结果,搜索用时 750 毫秒
991.
992.
Primary‐like human hepatocytes genetically engineered to obtain proliferation competence display hepatic differentiation characteristics in monolayer and organotypical spheroid cultures
下载免费PDF全文
![点击此处可从《Cell biology international》网站下载免费的PDF全文](/ch/ext_images/free.gif)
993.
Lentiviral expression of GAD67 and CCK promoter‐driven opsins to target interneurons in vitro and in vivo
下载免费PDF全文
![点击此处可从《The journal of gene medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
Georg Griesinger Pierre J. M. Verweij Davis Gates Paul Devroey Keith Gordon Barbara J. Stegmann Basil C. Tarlatzis 《PloS one》2016,11(3)
Study Question
What is the threshold for the prediction of moderate to severe or severe ovarian hyperstimulation syndrome (OHSS) based on the number of growing follicles ≥ 11 mm and/or estradiol (E2) levels?Summary Answer
The optimal threshold of follicles ≥11 mm on the day of hCG to identify those at risk was 19 for both moderate to severe OHSS and for severe OHSS. Estradiol (E2) levels were less prognostic of OHSS than the number of follicles ≥ 11 mm.What Is Known Already
In comparison to long gonadotropin-releasing hormone (GnRH) agonist protocols, the risk of severe OHSS is reduced by approximately 50% in a GnRH antagonist protocol for ovarian stimulation prior to in vitro fertilisation (IVF), while the two protocols provide equal chances of pregnancy per initiated cycle. Nevertheless, moderate to severe OHSS may still occur in GnRH antagonist protocols if human chorionic gonadotropin (hCG) is administered to trigger final oocyte maturation, especially in high responder patients. Severe OHSS following hCG trigger may occur with an incidence of 1–2% in a relatively young (aged 18 to 36 years) IVF population treated in a GnRH-antagonist protocol.Study Design, Size, Duration
From the Engage, Ensure and Trust trials, in total, 2,433 women who received hCG for oocyte maturation and for whom the number of follicles ≥ 11 mm and the level of E2 on the day of hCG administration were known were included in the analyses.Participants/Materials, Setting, Methods
The threshold for OHSS prediction of moderate and severe OHSS was assessed in women treated with corifollitropin alfa or daily recombinant follicle stimulation hormone (rFSH) in a gonadotropin-releasing hormone (GnRH)-antagonist protocol. Receiver operating characteristics curve analyses for moderate to severe OHSS and severe OHSS were performed on the combined dataset and the sensitivity and specificity for the optimal threshold of number of follicles ≥ 11 mm, E2 levels on the day of (hCG), and a combination of both, were determined.Main Results and the Role of Chance
The optimal threshold of follicles ≥ 11 mm on the day of hCG to identify those at risk of moderate to severe OHSS was 19 (sensitivity and specificity 62.3% and 75.6%, respectively) and for severe OHSS was also 19 (sensitivity and specificity 74.3% and 75.3%, respectively). The positive and negative predictive values were 6.9% and 98.6%, respectively, for moderate to severe OHSS, and 4.2% and 99.5% for severe OHSS.Limitations, Reasons for Caution
This was a retrospective analysis of combined data from three trials following ovarian stimulation with two different gonadotropins.Wider Implications of the Findings
For patients with 19 follicles or more ≥11 mm on the day of hCG, measures to prevent the development of OHSS should be considered. Secondary preventive measures include cycle cancellation or coasting, use of a GnRH agonist to trigger final oocyte maturation in place of hCG and a freeze all strategy.Trial Registration
ClinicalTrials.gov NCT00702845 NCT00696800 NCT00696878相似文献995.
Lore Schrutka Georg Goliasch Brigitte Meyer Raphael Wurm Lorenz Koller Lukas Kriechbaumer Gottfried Heinz Richard Pacher Irene M Lang Klaus Distelmaier Martin Hülsmann 《PloS one》2016,11(3)
Introduction
Oxidative stress affects clinical outcome in critically ill patients. Although high-density lipoprotein (HDL) particles generally possess anti-oxidant capacities, deleterious properties of HDL have been described in acutely ill patients. The impact of anti-oxidant HDL capacities on clinical outcome in critically ill patients is unknown. We therefore analyzed the predictive value of anti-oxidant HDL function on mortality in an unselected cohort of critically ill patients.Method
We prospectively enrolled 270 consecutive patients admitted to a university-affiliated intensive care unit (ICU) and determined anti-oxidant HDL function using the HDL oxidant index (HOI). Based on their HOI, the study population was stratified into patients with impaired anti-oxidant HDL function and the residual study population.Results
During a median follow-up time of 9.8 years (IQR: 9.2 to 10.0), 69% of patients died. Cox regression analysis revealed a significant and independent association between impaired anti-oxidant HDL function and short-term mortality with an adjusted HR of 1.65 (95% CI 1.22–2.24; p = 0.001) as well as 10-year mortality with an adj. HR of 1.19 (95% CI 1.02–1.40; p = 0.032) when compared to the residual study population. Anti-oxidant HDL function correlated with the amount of oxidative stress as determined by Cu/Zn superoxide dismutase (r = 0.38; p<0.001).Conclusion
Impaired anti-oxidant HDL function represents a strong and independent predictor of 30-day mortality as well as long-term mortality in critically ill patients. 相似文献996.
Biogas slurry, the secondary product of the anaerobic digestion process, is increasingly being used as fertilizer. Information is available on its chemical and physical properties and their effects on plant growth. However, there is a demand to characterize the microbial quality of slurries, which may control further mineralization processes after application to soil. In this study, biogas and raw slurries obtained from six farms were analyzed for their ergosterol and amino sugar concentrations as indices for microbial biomass. A reliable, precise method for determining ergosterol in slurries is presented. Biogas slurries contained significantly less ergosterol (?34%), muramic acid (MurN; ?42%), galactosamine (GalN; ?32%), and fungal glucosamine (GlcN; ?40%) than raw slurries. The mean fungal GlcN to ergosterol ratio (50) and also the mean fungal carbon (C) to bacterial C ratio (0.29) did not significantly differ between the slurry types. The mean microbial C concentration in the biogas slurries was significantly lower than in the raw slurries. Consequently, the contribution of microbial C to slurry organic C was 3.6% in the biogas slurries and 5.7% in the raw slurries. Microbial C revealed significant nonlinear relationships with the fiber and ash concentration, pH, as well as the C/N ratio of the slurries. 相似文献
997.
998.
Exploring mild enzymatic sustainable routes for the synthesis of bio‐degradable aromatic‐aliphatic oligoesters
下载免费PDF全文
![点击此处可从《Biotechnology journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alessandro Pellis Alice Guarneri Martin Brandauer Enrique Herrero Acero Henricus Peerlings Lucia Gardossi Georg M. Guebitz 《Biotechnology journal》2016,11(5):642-647
The application of Candida antarctica lipase B in enzyme‐catalyzed synthesis of aromatic‐aliphatic oligoesters is here reported. The aim of the present study is to systematically investigate the most favorable conditions for the enzyme catalyzed synthesis of aromatic‐aliphatic oligomers using commercially available monomers. Reaction conditions and enzyme selectivity for polymerization of various commercially available monomers were considered using different inactivated/activated aromatic monomers combined with linear polyols ranging from C2 to C12. The effect of various reaction solvents in enzymatic polymerization was assessed and toluene allowed to achieve the highest conversions for the reaction of dimethyl isophthalate with 1,4‐butanediol and with 1,10‐decanediol (88 and 87% monomer conversion respectively). Mw as high as 1512 Da was obtained from the reaction of dimethyl isophthalate with 1,10‐decanediol. The obtained oligomers have potential applications as raw materials in personal and home care formulations, for the production of aliphatic‐aromatic block co‐polymers or can be further functionalized with various moieties for a subsequent photo‐ or radical polymerization. 相似文献
999.
Georg?Wandrey Joel?Wurzel Kyra?Hoffmann Tobias?Ladner Jochen?Büchs Lorenz?Meinel Tessa?LühmannEmail author 《Journal of biological engineering》2016,10(1):11
Background
Genetic code expansion has developed into an elegant tool to incorporate unnatural amino acids (uAA) at predefined sites in the protein backbone in response to an amber codon. However, recombinant production and yield of uAA comprising proteins are challenged due to the additional translation machinery required for uAA incorporation.Results
We developed a microtiter plate-based high-throughput monitoring system (HTMS) to study and optimize uAA integration in the model protein enhanced green fluorescence protein (eGFP). Two uAA, propargyl-L-lysine (Plk) and (S)-2-amino-6-((2-azidoethoxy) carbonylamino) hexanoic acid (Alk), were incorporated at the same site into eGFP co-expressing the native PylRS/tRNAPyl CUA pair originating from Methanosarcina barkeri in E. coli. The site-specific uAA functionalization was confirmed by LC-MS/MS analysis. uAA-eGFP production and biomass growth in parallelized E. coli cultivations was correlated to (i) uAA concentration and the (ii) time of uAA addition to the expression medium as well as to induction parameters including the (iii) time and (iv) amount of IPTG supplementation. The online measurements of the HTMS were consolidated by end point-detection using standard enzyme-linked immunosorbent procedures.Conclusion
The developed HTMS is powerful tool for parallelized and rapid screening. In light of uAA integration, future applications may include parallelized screening of different PylRS/tRNAPyl CUA pairs as well as further optimization of culture conditions.1000.