全文获取类型
收费全文 | 1206篇 |
免费 | 74篇 |
出版年
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 37篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 38篇 |
2017年 | 28篇 |
2016年 | 37篇 |
2015年 | 68篇 |
2014年 | 63篇 |
2013年 | 90篇 |
2012年 | 100篇 |
2011年 | 93篇 |
2010年 | 56篇 |
2009年 | 49篇 |
2008年 | 74篇 |
2007年 | 88篇 |
2006年 | 73篇 |
2005年 | 62篇 |
2004年 | 61篇 |
2003年 | 36篇 |
2002年 | 39篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1995年 | 14篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 6篇 |
1970年 | 2篇 |
1969年 | 5篇 |
1968年 | 2篇 |
1965年 | 2篇 |
1950年 | 2篇 |
1943年 | 2篇 |
排序方式: 共有1280条查询结果,搜索用时 15 毫秒
31.
32.
Bartłomiej Wyżga Paweł Oglęcki Hanna Hajdukiewicz Joanna Zawiejska Artur Radecki-Pawlik Tomasz Skalski Paweł Mikuś 《Hydrobiologia》2013,712(1):71-88
Like its British prototype (Biological Monitoring Working Party score system), the Polish benthic invertebrate-based BMWP-PL index is commonly regarded as an indicator of river water quality. This interpretation of the index has been verified in a study of the gravel-bed Bia?a River. Benthic macroinvertebrates were sampled at 10 sites and compared in one channelized and one unmanaged cross-section per site. The resulting taxa richness and BMWP-PL index scores were compared with water quality and physical habitat characteristics in the cross-sections. Channelized and unmanaged cross-sections clearly differed in their physical habitat conditions, and water quality characteristics mostly varied in the downstream direction. Particular cross-sections hosted between 3 and 26 invertebrate taxa, with the respective BMWP-PL scores indicating the water in the surveyed cross-sections varied between high and poor quality. However, the BMWP-PL scores were unrelated to physicochemical characteristics of the river water, which consistently pointed to high water quality. Instead, the scores were significantly related to several physical habitat variables, with the number of low-flow channels in a cross-section explaining the largest proportion of the variance in the index values. The relationship of the scores with the complexity of flow pattern in the river and a lack of their dependence on physicochemical water characteristics show that the BMWP-PL index should not be regarded as an indicator of water quality but rather as an indicator of the ecological status of rivers, dependent both on their hydromorphological and water-quality characteristics. 相似文献
33.
Magdalena Banas Katarzyna Zabieglo Gopinath Kasetty Monika Kapinska-Mrowiecka Julia Borowczyk Justyna Drukala Krzysztof Murzyn Brian A. Zabel Eugene C. Butcher Jens M. Schroeder Artur Schmidtchen Joanna Cichy 《PloS one》2013,8(3)
Chemerin, a chemoattractant ligand for chemokine-like receptor 1 (CMKLR1) is predicted to share similar tertiary structure with antibacterial cathelicidins. Recombinant chemerin has antimicrobial activity. Here we show that endogenous chemerin is abundant in human epidermis, and that inhibition of bacteria growth by exudates from organ cultures of primary human skin keratinocytes is largely chemerin-dependent. Using a panel of overlapping chemerin-derived synthetic peptides, we demonstrate that the antibacterial activity of chemerin is primarily mediated by Val66-Pro85, which causes direct bacterial lysis. Therefore, chemerin is an antimicrobial agent in human skin. 相似文献
34.
Szymańska-Chargot Monika Chylińska Monika Pieczywek Piotr M. Rösch Petra Schmitt Michael Popp Jürgen Zdunek Artur 《Planta》2016,243(4):935-945
Planta - Du ring on-tree ripening, the pectin distribution changed from polydispersed in cell wall to cumulated in cell wall corners. During apple storage, the pectin distribution returned to... 相似文献
35.
Ewa Maczynska Karol Karnowski Krzysztof Szulzycki Monika Malinowska Hubert Dolezyczek Artur Cichanski Maciej Wojtkowski Bartlomiej Kaluzny Ireneusz Grulkowski 《Journal of biophotonics》2019,12(2)
Application of the air‐puff swept source optical coherence tomography (SS‐OCT) instrument to determine the influence of viscoelasticity on the relation between overall the air‐puff force and corneal apex displacement of porcine corneas ex vivo is demonstrated. Simultaneous recording of time‐evolution of the tissue displacement and air pulse stimulus allows obtaining valuable information related in part to the mechanical properties of the cornea. A novel approach based on quantitative analysis of the corneal hysteresis of OCT data is presented. The corneal response to the air pulse is assessed for different well‐controlled intraocular pressure (IOP) levels and for the progression of cross‐linking‐induced stiffness of the cornea. Micrometer resolution, fast acquisition and noncontact character of the air‐puff SS‐OCT measurements have potential to improve the in vivo assessment of mechanical properties of the human corneas. 相似文献
36.
Schromm AB Howe J Ulmer AJ Wiesmüller KH Seyberth T Jung G Rössle M Koch MH Gutsmann T Brandenburg K 《The Journal of biological chemistry》2007,282(15):11030-11037
The importance of the biological function and activity of lipoproteins from the outer or cytoplasmic membranes of Gram-positive and Gram-negative bacteria is being increasingly recognized. It is well established that they are like the endotoxins (lipopolysaccharide (LPS)), which are the main amphiphilic components of the outer membrane of Gram-negative bacteria, potent stimulants of the human innate immune system, and elicit a variety of proinflammatory immune responses. Investigations of synthetic lipopeptides corresponding to N-terminal partial structures of bacterial lipoproteins defined the chemical prerequisites for their biological activity and in particular the number and length of acyl chains and sequence of the peptide part. Here we present experimental data on the biophysical mechanisms underlying lipopeptide bioactivity. Investigation of selected synthetic diacylated and triacylated lipopeptides revealed that the geometry of these molecules (i.e. the molecular conformations and supramolecular aggregate structures) and the preference for membrane intercalation provide an explanation for the biological activities of the different lipopeptides. This refers in particular to the agonistic or antagonistic activity (i.e. their ability to induce cytokines in mononuclear cells or to block this activity, respectively). Biological activity of lipopeptides was hardly affected by the LPS-neutralizing antibiotic polymyxin B, and the biophysical interaction characteristics were found to be in sharp contrast to that of LPS with polymyxin B. The analytical data show that our concept of "endotoxic conformation," originally developed for LPS, can be applied also to the investigated lipopeptide and suggest that the molecular mechanisms of cell activation by amphiphilic molecules are governed by a general principle. 相似文献
37.
38.
Betekhtin Alexander Pinski Artur Milewska-Hendel Anna Kurczynska Ewa Hasterok Robert 《Plant Cell, Tissue and Organ Culture》2019,137(2):343-357
Plant Cell, Tissue and Organ Culture (PCTOC) - The morphogenic callus (MC) of Fagopyrum tataricum contains a large amount of flavonoids, especially rutin, and exhibits a high level of antioxidant... 相似文献
39.
A postmitotic role for Isl-class LIM homeodomain proteins in the assignment of visceral spinal motor neuron identity 总被引:5,自引:0,他引:5
LIM homeobox genes have a prominent role in the regulation of neuronal subtype identity and distinguish motor neuron subclasses in the embryonic spinal cord. We have investigated the role of Isl-class LIM homeodomain proteins in motor neuron diversification using mouse genetic methods. All spinal motor neuron subtypes initially express both Isl1 and Isl2, but Isl2 is rapidly downregulated by visceral motor neurons. Mouse embryos lacking Isl2 function exhibit defects in the migration and axonal projections of thoracic level motor neurons that appear to reflect a cell-autonomous switch from visceral to somatic motor neuron character. Additional genetic mutations that reduce or eliminate both Isl1 and Isl2 activity result in more pronounced defects in visceral motor neuron generation and erode somatic motor neuron character. Thus, an early phase of high Isl expression and activity in newly generated motor neurons permits the diversification of visceral and somatic motor neuron subtypes in the developing spinal cord. 相似文献
40.
Joanna?Lesicka Paulina?Piontek Zofia?Szweykowska-Kuli ska Artur?Jarmo?owskiEmail author 《Acta Physiologiae Plantarum》2004,26(3):363-369
Small RNAs have been recently discovered as important regulators of gene expression in Eukaryota. This review compares two
categories of small RNAs existing in plants: short interfering RNAs (siRNAs) and microRNAs (miRNAs) and reveals similarities
and differences between two intriguing processes: RNA degradation and translational repression directed by small RNAs. The
disruption of miRNA-mediated regulation causes developmental abnormalities in plants, proving a fundamental role of miRNAs. 相似文献