全文获取类型
收费全文 | 4052篇 |
免费 | 372篇 |
国内免费 | 3篇 |
专业分类
4427篇 |
出版年
2023年 | 30篇 |
2022年 | 60篇 |
2021年 | 131篇 |
2020年 | 79篇 |
2019年 | 92篇 |
2018年 | 115篇 |
2017年 | 106篇 |
2016年 | 171篇 |
2015年 | 309篇 |
2014年 | 275篇 |
2013年 | 270篇 |
2012年 | 444篇 |
2011年 | 359篇 |
2010年 | 231篇 |
2009年 | 187篇 |
2008年 | 267篇 |
2007年 | 240篇 |
2006年 | 197篇 |
2005年 | 189篇 |
2004年 | 133篇 |
2003年 | 129篇 |
2002年 | 107篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 12篇 |
1998年 | 27篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1985年 | 5篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1969年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有4427条查询结果,搜索用时 18 毫秒
31.
During the studies on the Turkish Braconidae, a new species Bracon (Lucobracon) iskilipus sp. n. from the Turkish Central Black Sea region was recorded. Bracon (Lucobracon) iskilipus sp. n. was described, its morphological diagnostic characters were illustrated and it was compared with the related Bracon (Lucobracon) moczari Papp. 相似文献
32.
33.
Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献
34.
35.
36.
P450 BM3: the very model of a modern flavocytochrome 总被引:4,自引:0,他引:4
Munro AW Leys DG McLean KJ Marshall KR Ost TW Daff S Miles CS Chapman SK Lysek DA Moser CC Page CC Dutton PL 《Trends in biochemical sciences》2002,27(5):250-257
Flavocytochrome P450 BM3 is a bacterial P450 system in which a fatty acid hydroxylase P450 is fused to a mammalian-like diflavin NADPH-P450 reductase in a single polypeptide. The enzyme is soluble (unlike mammalian P450 redox systems) and its fusion arrangement affords it the highest catalytic activity of any P450 mono-oxygenase. This article discusses the fundamental properties of P450 BM3 and how progress with this model P450 has affected our comprehension of P450 systems in general. 相似文献
37.
Ulf Soppa Julian Schumacher Victoria Florencio Ortiz Tobias Pasqualon Francisco Tejedor 《Cell cycle (Georgetown, Tex.)》2014,13(13):2084-2100
A fundamental question in neurobiology is how the balance between proliferation and differentiation of neuronal precursors is maintained to ensure that the proper number of brain neurons is generated. Substantial evidence implicates DYRK1A (dual specificity tyrosine-phosphorylation-regulated kinase 1A) as a candidate gene responsible for altered neuronal development and brain abnormalities in Down syndrome. Recent findings support the hypothesis that DYRK1A is involved in cell cycle control. Nonetheless, how DYRK1A contributes to neuronal cell cycle regulation and thereby affects neurogenesis remains poorly understood. In the present study we have investigated the mechanisms by which DYRK1A affects cell cycle regulation and neuronal differentiation in a human cell model, mouse neurons, and mouse brain. Dependent on its kinase activity and correlated with the dosage of overexpression, DYRK1A blocked proliferation of SH-SY5Y neuroblastoma cells within 24 h and arrested the cells in G1 phase. Sustained overexpression of DYRK1A induced G0 cell cycle exit and neuronal differentiation. Furthermore, we provide evidence that DYRK1A modulated protein stability of cell cycle-regulatory proteins. DYRK1A reduced cellular Cyclin D1 levels by phosphorylation on Thr286, which is known to induce proteasomal degradation. In addition, DYRK1A phosphorylated p27Kip1 on Ser10, resulting in protein stabilization. Inhibition of DYRK1A kinase activity reduced p27Kip1 Ser10 phosphorylation in cultured hippocampal neurons and in embryonic mouse brain. In aggregate, these results suggest a novel mechanism by which overexpression of DYRK1A may promote premature neuronal differentiation and contribute to altered brain development in Down syndrome. 相似文献
38.
Lorenzo Galluzzi Ilio Vitale Laura Senovilla Tobias Eisenberg Didac Carmona-Gutierrez Erika Vacchelli Thomas Robert Hugues Ripoche Nora J?gemann Caroline Paccard Nicolas Servant Philippe Hupé Vladimir Lazar Philippe Dessen Emmanuel Barillot Hans Zischka Frank Madeo Guido Kroemer 《Cell cycle (Georgetown, Tex.)》2012,11(18):3472-3480
39.
Ferruh Artunc Christian Mueller Tobias Breidthardt Raphael Twerenbold Andreas Peter Claus Thamer Peter Weyrich Hans-Ulrich Haering Bjoern Friedrich 《PloS one》2012,7(10)
Background
In hemodialysis patients, elevated plasma troponin concentrations are a common finding that has even increased with the advent of newly developed sensitive assays. However, the interpretation and relevance of this is still under debate.Methods
In this cross-sectional study, we analyzed plasma concentrations of sensitive troponin I (TnI) and troponin T (TnT) in stable ambulatory hemodialysis patients (n = 239) and investigated their associations with clinical factors and mortality.Results
In all of the enrolled patients, plasma TnI or TnT was detectable at a median concentration of 14 pg/ml (interquartile range: 7–29) using the Siemens TnI ultra assay and 49 pg/ml (31–74) using the Roche Elecsys high sensitive TnT assay. Markedly more patients exceeded the 99th percentile for TnT than for TnI (95% vs. 14%, p<0.0001). In a multivariate linear regression model, TnT was independently associated with age, gender, systolic dysfunction, time on dialysis, residual diuresis and systolic blood pressure, whereas TnI was independently associated with age, systolic dysfunction, pulse pressure, time on dialysis and duration of a HD session. During a follow-up period of nearly two years, TnT concentration above 38 pg/mL was associated with a 5-fold risk of death, whereas elevation of TnI had a gradual association to mortality.Conclusion
In hemodialysis patients, elevations of plasma troponin concentrations are explained by cardiac function and dialysis-related parameters, which contribute to cardiac strain. Both are highly predictive of increased risk of death. 相似文献40.
Robert Kaba Alhassan Edward Nketiah-Amponsah Nicole Spieker Daniel Kojo Arhinful Alice Ogink Paul van Ostenberg Tobias F. Rinke de Wit 《PloS one》2015,10(11)