全文获取类型
收费全文 | 3950篇 |
免费 | 289篇 |
国内免费 | 1篇 |
出版年
2023年 | 15篇 |
2022年 | 41篇 |
2021年 | 74篇 |
2020年 | 69篇 |
2019年 | 66篇 |
2018年 | 55篇 |
2017年 | 64篇 |
2016年 | 104篇 |
2015年 | 163篇 |
2014年 | 196篇 |
2013年 | 240篇 |
2012年 | 310篇 |
2011年 | 298篇 |
2010年 | 172篇 |
2009年 | 134篇 |
2008年 | 252篇 |
2007年 | 197篇 |
2006年 | 199篇 |
2005年 | 188篇 |
2004年 | 178篇 |
2003年 | 152篇 |
2002年 | 124篇 |
2001年 | 62篇 |
2000年 | 61篇 |
1999年 | 61篇 |
1998年 | 43篇 |
1997年 | 30篇 |
1996年 | 25篇 |
1995年 | 36篇 |
1994年 | 36篇 |
1993年 | 33篇 |
1992年 | 27篇 |
1991年 | 38篇 |
1990年 | 40篇 |
1989年 | 23篇 |
1988年 | 37篇 |
1987年 | 21篇 |
1986年 | 26篇 |
1985年 | 19篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1976年 | 20篇 |
1974年 | 14篇 |
1973年 | 23篇 |
1971年 | 17篇 |
1970年 | 18篇 |
1968年 | 22篇 |
排序方式: 共有4240条查询结果,搜索用时 15 毫秒
101.
Für eine effiziente Resistenzzüchtung stellt eine Resistenzprüfmethode, die eine schnelle und zuverlässige Evaluierung einer möglichst großen Zahl von Genotypen erlaubt, eine wichtige Voraussetzung dar. Für das Freiland wurde eine Preßluftinjektionsmethode entwickelt, die eine nahezu 100 %ige Infektion von Maispflanzen mit dem Zuckerrohrmosaik‐Virus (sugarcane mosaic virus, SCMV) und dem Maisver‐zwergungsmosaik‐Virus (maize dwarf mosaic virus, MDMV) garantiert. Bei den empfindlicheren Pflanzen im Gewächshaus hatte eine mechanische Inokulation von Hand Vorteile. 相似文献
102.
The steroid-binding properties of recombinant glucocorticoid receptor: a putative role for heat shock protein hsp90 总被引:2,自引:0,他引:2
Y Ohara-Nemoto P E Str?mstedt K Dahlman-Wright T Nemoto J A Gustafsson J Carlstedt-Duke 《The Journal of steroid biochemistry and molecular biology》1990,37(4):481-490
The steroid-binding domain of the human glucocorticoid receptor was expressed in Escherichia coli either as a fusion protein with protein A or under control of the T7 RNA polymerase promoter. The recombinant proteins were found to bind steroids with the normal specificity for a glucocorticoid receptor but with reduced affinity (Kd for triamcinolone acetonide approximately 70 nM). Glycerol gradient analysis of the E. coli lystate containing the recombinant protein indicated no interaction between the glucocorticoid receptor fragment and heat shock proteins. However, synthesis of the corresponding fragments of glucocorticoid receptor in vitro using rabbit reticulocyte lystate resulted in the formation of proteins that bound triamcinolone acetonide with high affinity (Kd 2nM). Glycerol gradient analysis of these proteins, with and without molybdate, indicated that the in vitro synthesised receptor fragments formed complexes with hsp90 as previously shown for the full-length rat glucocorticoid receptor. Radiosequence analysis of the recombinant steroid-binding domain expressed in E. coli and affinity labelled with dexamethasone mesylate identified binding of the steroid to Cys-638 predominantly. However, all cysteine residues within the steroid-binding domain were affinity labelled to a certain degree indicating that the recombinant protein has a structure similar to the native receptor but more open and accessible. 相似文献
103.
Luttge Ulrich; Osmond C. Barry; Ball Erika; Brinckmann Enno; Kinze Gabriele 《Plant & cell physiology》1972,13(3):505-514
Bisulfite compounds are shown to be nonspecific inhibitors ofphotosynthetic processes and of ion transport in green tissues.CO2 fixation and light-dependent transient changes in externalpH are inhibited about 50% by 5x104 M glyoxal-Na-bisulfite.Chloride uptake in the light and in the dark is inhibited tothe same extent at this concentration. At 5x103 M theinhibitor reduces ATP levels in the light and in the dark, andeffects on glycolate oxidase and PEP carboxylase are observed.The extent of inhibition is dependent on time of treatment withglyoxal-Na-bisulfite and freshly prepared NaHSO3 is equallyas effective as the addition compound. Possible explanations of the bisulfite effects and the relationshipsto SO2 effects on photosynthesis are discussed. (Received September 1, 1971; ) 相似文献
104.
Erika C. Freeman Irena F. Creed Blake Jones Ann‐Kristin Bergstrm 《Global Change Biology》2020,26(9):4966-4987
The interacting effects of global changes—including increased temperature, altered precipitation, reduced acidification and increased dissolved organic matter loads to lakes—are anticipated to create favourable environmental conditions for cyanobacteria in northern lakes. However, responses of cyanobacteria to these global changes are complex, if not contradictory. We hypothesized that absolute and relative biovolumes of cyanobacteria (both total and specific genera) are increasing in Swedish nutrient‐poor lakes and that these increases are associated with global changes. We tested these hypotheses using data from 28 nutrient‐poor Swedish lakes over 16 years (1998–2013). Increases in cyanobacteria relative biovolume were identified in 21% of the study sites, primarily in the southeastern region of Sweden, and were composed mostly of increases from three specific genera: Merismopedia, Chroococcus and Dolichospermum. Taxon‐specific changes were related to different environmental stressors; that is, increased surface water temperature favoured higher Merismopedia relative biovolume in low pH lakes with high nitrogen to phosphorus ratios, whereas acidification recovery was statistically related to increased relative biovolumes of Chroococcus and Dolichospermum. In addition, enhanced dissolved organic matter loads were identified as potential determinants of Chroococcus suppression and Dolichospermum promotion. Our findings highlight that specific genera of cyanobacteria benefit from different environmental changes. Our ability to predict the risk of cyanobacteria prevalence requires consideration of the environmental condition of a lake and the sensitivities of the cyanobacteria genera within the lake. Regional patterns may emerge due to spatial autocorrelations within and among lake history, rates and direction of environmental change and the niche space occupied by specific cyanobacteria. 相似文献
105.
Clemens Alexander Boecker Mara A. Olenick Elizabeth R. Gallagher Michael E. Ward Erika L. F. Holzbaur 《Traffic (Copenhagen, Denmark)》2020,21(1):138-155
Induced pluripotent stem cells (iPSCs) hold promise to revolutionize studies of intracellular transport in live human neurons and to shed new light on the role of dysfunctional transport in neurodegenerative disorders. Here, we describe an approach for live imaging of axonal and dendritic transport in iPSC‐derived cortical neurons. We use transfection and transient expression of genetically‐encoded fluorescent markers to characterize the motility of Rab‐positive vesicles, including early, late and recycling endosomes, as well as autophagosomes and mitochondria in iPSC‐derived neurons. Comparing transport parameters of these organelles with data from primary rat hippocampal neurons, we uncover remarkable similarities. In addition, we generated lysosomal‐associated membrane protein 1 (LAMP1)‐enhanced green fluorescent protein (EGFP) knock‐in iPSCs and show that knock‐in neurons can be used to study the transport of endogenously labeled vesicles, as a parallel approach to the transient overexpression of fluorescently labeled organelle markers. 相似文献
106.
107.
Pedrotta Tiziana Gobet Erika Schwörer Christoph Beffa Giorgia Butz Christoph Henne Paul D. Morales-Molino César Pasta Salvatore van Leeuwen Jacqueline F. N. Vogel Hendrik Zwimpfer Elias Anselmetti Flavio S. Grosjean Martin Tinner Willy 《Vegetation History and Archaeobotany》2021,30(6):789-813
Vegetation History and Archaeobotany - Knowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record... 相似文献
108.
109.
Tóth Ákos Bata-Vidács Ildikó Kosztik Judit Máté Rózsa Kutasi József Tóth Erika Bóka Károly Táncsics András Nagy István Kovács Gábor Kukolya József 《Antonie van Leeuwenhoek》2021,114(10):1575-1584
Antonie van Leeuwenhoek - A Gram-reaction-negative halotolerant bacterial strain, designated Ka21T, was isolated from agricultural soil and characterised using a polyphasic approach to determine... 相似文献
110.
Kelly E. Leon Raquel Buj Elizabeth Lesko Erika S. Dahl Chi-Wei Chen Naveen Kumar Tangudu Yuka Imamura-Kawasawa Andrew V. Kossenkov Ryan P. Hobbs Katherine M. Aird 《The Journal of cell biology》2021,220(8)
Oncogene-induced senescence (OIS) is a stable cell cycle arrest that occurs in normal cells upon oncogene activation. Cells undergoing OIS express a wide variety of secreted factors that affect the senescent microenvironment termed the senescence-associated secretory phenotype (SASP), which is beneficial or detrimental in a context-dependent manner. OIS cells are also characterized by marked epigenetic changes. We globally assessed histone modifications of OIS cells and discovered an increase in the active histone marks H3K79me2/3. The H3K79 methyltransferase disruptor of telomeric silencing 1-like (DOT1L) was necessary and sufficient for increased H3K79me2/3 occupancy at the IL1A gene locus, but not other SASP genes, and was downstream of STING. Modulating DOT1L expression did not affect the cell cycle arrest. Together, our studies establish DOT1L as an epigenetic regulator of the SASP, whose expression is uncoupled from the senescence-associated cell cycle arrest, providing a potential strategy to inhibit the negative side effects of senescence while maintaining the beneficial inhibition of proliferation. 相似文献