全文获取类型
收费全文 | 7898篇 |
免费 | 731篇 |
国内免费 | 2篇 |
专业分类
8631篇 |
出版年
2024年 | 4篇 |
2023年 | 41篇 |
2022年 | 81篇 |
2021年 | 181篇 |
2020年 | 117篇 |
2019年 | 136篇 |
2018年 | 170篇 |
2017年 | 177篇 |
2016年 | 220篇 |
2015年 | 417篇 |
2014年 | 466篇 |
2013年 | 591篇 |
2012年 | 727篇 |
2011年 | 697篇 |
2010年 | 439篇 |
2009年 | 408篇 |
2008年 | 563篇 |
2007年 | 504篇 |
2006年 | 494篇 |
2005年 | 436篇 |
2004年 | 459篇 |
2003年 | 327篇 |
2002年 | 371篇 |
2001年 | 80篇 |
2000年 | 43篇 |
1999年 | 70篇 |
1998年 | 88篇 |
1997年 | 53篇 |
1996年 | 31篇 |
1995年 | 26篇 |
1994年 | 25篇 |
1993年 | 31篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1973年 | 3篇 |
1967年 | 2篇 |
1960年 | 3篇 |
排序方式: 共有8631条查询结果,搜索用时 0 毫秒
991.
992.
Recent advances in mass spectrometry will soon allow routine analysis of protein expression levels. How close are we to true quantitative proteomics? 相似文献
993.
Olivia Majer Christelle Bourgeois Florian Zwolanek Caroline Lassnig Dontscho Kerjaschki Matthias Mack Mathias Müller Karl Kuchler 《PLoS pathogens》2012,8(7)
Invasive fungal infections by Candida albicans (Ca) are a frequent cause of lethal sepsis in intensive care unit patients. While a contribution of type I interferons (IFNs-I) in fungal sepsis remains unknown, these immunostimulatory cytokines mediate the lethal effects of endotoxemia and bacterial sepsis. Using a mouse model lacking a functional IFN-I receptor (Ifnar1−/−), we demonstrate a remarkable protection against invasive Ca infections. We discover a mechanism whereby IFN-I signaling controls the recruitment of inflammatory myeloid cells, including Ly6Chi monocytes and neutrophils, to infected kidneys by driving expression of the chemokines CCL2 and KC. Within kidneys, monocytes differentiate into inflammatory DCs but fail to functionally mature in Ifnar1−/− mice, as demonstrated by the impaired upregulation of the key activation markers PDCA1 and iNOS. The increased activity of inflammatory monocytes and neutrophils results in hyper-inflammation and lethal kidney pathology. Pharmacological diminution of monocytes and neutrophils by treating mice with pioglitazone, a synthetic agonist of the nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ), strongly reduces renal immunopathology during Ca infection and improves mouse survival. Taken together, our data connect for the first time the sepsis-promoting functions of IFNs-I to the CCL2-mediated recruitment and the activation of inflammatory monocytes/DCs with high host-destructing potency. Moreover, our data demonstrate a therapeutic relevance of PPAR-γ agonists for microbial infectious diseases where inflammatory myeloid cells may contribute to fatal tissue damage. 相似文献
994.
995.
Almost all large-scale projects in mass spectrometry-based proteomics use trypsin to convert protein mixtures into more readily analyzable peptide populations. When searching peptide fragmentation spectra against sequence databases, potentially matching peptide sequences can be required to conform to tryptic specificity, namely, cleavage exclusively C-terminal to arginine or lysine. In many published reports, however, significant numbers of proteins are identified by non-tryptic peptides. Here we use the sub-parts per million mass accuracy of a new ion trap Fourier transform mass spectrometer to achieve more than a 100-fold increased confidence in peptide identification compared with typical ion trap experiments and show that trypsin cleaves solely C-terminal to arginine and lysine. We find that non-tryptic peptides occur only as the C-terminal peptides of proteins and as breakup products of fully tryptic peptides N-terminal to an internal proline. Simulating lower mass accuracy led to a large number of proteins erroneously identified with non-tryptic peptide hits. Our results indicate that such peptide hits in previous studies should be re-examined and that peptide identification should be based on strict trypsin specificity. 相似文献
996.
997.
Matthias Lergenmüller Ulrich Klres Frieder W. Lichtenthaler 《Carbohydrate research》2009,344(16):2127-2136
Koenigs–Knorr-type glycosidations of peracylated 2Z-benzoyloxyimino-glycopyranosyl bromides invariably proceed with retention of the Z-geometry. Accordingly, the many β-d-hexosidulose oximes in literature which were prepared in this way and for which the oxime geometry has not been addressed explicitly, are the Z-oximes throughout. By contrast, oximation of β-d-hexopyranosid-2-uloses leads to mixtures of E and Z oximes readily separable and structurally verifiable by 1H and 13C NMR. Configurational assignments rested on comparative evaluation of NMR data of E and Z isomers, and, most notably on an X-ray structural analysis of the pivaloylated isopropyl 2E-benzoyloxyimino-2-deoxy-β-d-arabino-hexopyranoside revealing the unusual 1S51,4B conformation for the pyranoid ring. 相似文献
998.
Homology modeling revealed more than 20,000 rRNA internal transcribed spacer 2 (ITS2) secondary structures 总被引:4,自引:0,他引:4 下载免费PDF全文
Structural genomics meets phylogenetics and vice versa: Knowing rRNA secondary structures is a prerequisite for constructing rRNA alignments for inferring phylogenies, and inferring phylogenies is a precondition to understand the evolution of such rRNA secondary structures. Here, both scientific worlds go together. The rRNA internal transcribed spacer 2 (ITS2) region is a widely used phylogenetic marker. Because of its high variability at the sequence level, correct alignments have to take into account structural information. In this study, we examine the extent of the conservation in structure. We present (1) the homology modeled secondary structure of more than 20,000 ITS2 covering about 14,000 species; (2) a computational approach for homology modeling of rRNA structures, which additionally can be applied to other RNA families; and (3) a database providing about 25,000 ITS2 sequences with their associated secondary structures, a refined ITS2 specific general time reversible (GTR) substitution model, and a scoring matrix, available at http://its2.bioapps.biozentrum.uni-wuerzburg.de. 相似文献
999.
Elias T. Ayuk Bahiru Duguma Steve Franzel Joseph Kengue Matthias Mollet Theophile Tiki-Manga Pauline Zekeng 《Economic botany》1999,53(3):292-301
Dacryodes edulis is one of the most preferred tree species by farmers in the humid lowlands of Cameroon. The fruit of the species figures prominently in cross-boundary trade between Cameroon, Nigeria and Gabon. Although there exist empirical data on the volume of trade of the fruit at this level, no data are available at the farm level. A field survey was undertaken to identify uses, management, and farmers’ improvement objectives and to quantify, at the farm-level, the economic potential of the species. The results of the survey indicate thatD. edulis is widely planted and found mainly in tree crop fields and in home gardens. The fruit is highly consumed and traded. The farm-level value of fruit production reaches $US161 a year per grower or collector. The dead branches of the species are used as firewood and its bark is used as medicine. Desired improvement objectives include increased fruit size, good tasting fruit, high yield and reduced time to bearing. 相似文献
1000.