全文获取类型
收费全文 | 729篇 |
免费 | 56篇 |
出版年
2021年 | 10篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2016年 | 13篇 |
2015年 | 17篇 |
2014年 | 19篇 |
2013年 | 37篇 |
2012年 | 30篇 |
2011年 | 29篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 35篇 |
2007年 | 31篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 26篇 |
1998年 | 6篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 7篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1967年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有785条查询结果,搜索用时 15 毫秒
71.
Jolanta Kolodziejek Bernhard Seidel Christof Jungbauer Katharina Dimmel Michael Kolodziejek Ivo Rudolf Zdenek Hubálek Franz Allerberger Norbert Nowotny 《PloS one》2015,10(5)
The detection of West Nile virus (WNV) nucleic acid in a blood donation from Vienna, Austria, as well as in Culex pipiens pupae and egg rafts, sampled close to the donor’s residence, is reported. Complete genomic sequences of the human- and mosquito-derived viruses were established, genetically compared and phylogenetically analyzed. The viruses were not identical, but closely related to each other and to recent Czech and Italian isolates, indicating co-circulation of related WNV strains within a confined geographic area. The detection of WNV in a blood donation originating from an area with low WNV prevalence in humans (only three serologically diagnosed cases between 2008 and 2014) is surprising and emphasizes the importance of WNV nucleic acid testing of blood donations even in such areas, along with active mosquito surveillance programs. 相似文献
72.
Philipp Rausch Natalie Steck Abdulhadi Suwandi Janice A. Seidel Sven Künzel Kirandeep Bhullar Marijana Basic Andre Bleich Jill M. Johnsen Bruce A. Vallance John F. Baines Guntram A. Grassl 《PLoS pathogens》2015,11(7)
Glycans play important roles in host-microbe interactions. Tissue-specific expression patterns of the blood group glycosyltransferase β-1,4-N-acetylgalactosaminyltransferase 2 (B4galnt2) are variable in wild mouse populations, and loss of B4galnt2 expression is associated with altered intestinal microbiota. We hypothesized that variation in B4galnt2 expression alters susceptibility to intestinal pathogens. To test this, we challenged mice genetically engineered to express different B4galnt2 tissue-specific patterns with a Salmonella Typhimurium infection model. We found B4galnt2 intestinal expression was strongly associated with bacterial community composition and increased Salmonella susceptibility as evidenced by increased intestinal inflammatory cytokines and infiltrating immune cells. Fecal transfer experiments demonstrated a crucial role of the B4galnt2-dependent microbiota in conferring susceptibility to intestinal inflammation, while epithelial B4galnt2 expression facilitated epithelial invasion of S. Typhimurium. These data support a critical role for B4galnt2 in gastrointestinal infections. We speculate that B4galnt2-specific differences in host susceptibility to intestinal pathogens underlie the strong signatures of balancing selection observed at the B4galnt2 locus in wild mouse populations. 相似文献
73.
Andrew T. Miller Carol Dahlberg Mark L. Sandberg Ben G. Wen Daniel R. Beisner John A. H. Hoerter Albert Parker Christian Schmedt Monique Stinson Jacqueline Avis Cynthia Cienfuegos Mark McPate Pamela Tranter Martin Gosling Paul J. Groot-Kormelink Janet Dawson Shifeng Pan Shin-Shay Tian H. Martin Seidel Michael P. Cooke 《PloS one》2015,10(6)
Emerging approaches to treat immune disorders target positive regulatory kinases downstream of antigen receptors with small molecule inhibitors. Here we provide evidence for an alternative approach in which inhibition of the negative regulatory inositol kinase Itpkb in mature T lymphocytes results in enhanced intracellular calcium levels following antigen receptor activation leading to T cell death. Using Itpkb conditional knockout mice and LMW Itpkb inhibitors these studies reveal that Itpkb through its product IP4 inhibits the Orai1/Stim1 calcium channel on lymphocytes. Pharmacological inhibition or genetic deletion of Itpkb results in elevated intracellular Ca2+ and induction of FasL and Bim resulting in T cell apoptosis. Deletion of Itpkb or treatment with Itpkb inhibitors blocks T-cell dependent antibody responses in vivo and prevents T cell driven arthritis in rats. These data identify Itpkb as an essential mediator of T cell activation and suggest Itpkb inhibition as a novel approach to treat autoimmune disease. 相似文献
74.
Roberta Bianchi Alvaro Teijeira Steven T. Proulx Ailsa J. Christiansen Catharina D. Seidel Thomas Rülicke Taija M?kinen René H?gerling Cornelia Halin Michael Detmar 《PloS one》2015,10(4)
The lymphatic vascular system plays an active role in immune cell trafficking, inflammation and cancer spread. In order to provide an in vivo tool to improve our understanding of lymphatic vessel function in physiological and pathological conditions, we generated and characterized a tdTomato reporter mouse and crossed it with a mouse line expressing Cre recombinase under the control of the lymphatic specific promoter Prox1 in an inducible fashion. We found that the tdTomato fluorescent signal recapitulates the expression pattern of Prox1 in lymphatic vessels and other known Prox1-expressing organs. Importantly, tdTomato co-localized with the lymphatic markers Prox1, LYVE-1 and podoplanin as assessed by whole-mount immunofluorescence and FACS analysis. The tdTomato reporter was brighter than a previously established red fluorescent reporter line. We confirmed the applicability of this animal model to intravital microscopy of dendritic cell migration into and within lymphatic vessels, and to fluorescence-activated single cell analysis of lymphatic endothelial cells. Additionally, we were able to describe the early morphological changes of the lymphatic vasculature upon induction of skin inflammation. The Prox1-Cre-tdTomato reporter mouse thus shows great potential for lymphatic research. 相似文献
75.
Ivanova Bojidarka B. Seidel Rüdiger W. Kolev Tsonko Sheldrick William Spiteller Michael 《Amino acids》2010,39(1):309-314
The title compound, 2-(phenylethyl)ammonium hydrogensquarate hemihydrate, was synthesized and structurally and spectroscopically
characterized by a single crystal X-ray diffraction and solid-state polarized IR spectroscopy of oriented colloids in a nematic
host. The crystal structure consists of two crystallographically independent 2-(phenylethyl)ammonium cations, joined in a
2D hydrogen-bonded network with hydrogensquarate anions and solvent water molecules. Surprisingly, the crystallographically
non-equivalent cations exhibit differing pseudo T and G trans configurations. 相似文献
76.
77.
Martone PT Boller M Burgert I Dumais J Edwards J Mach K Rowe N Rueggeberg M Seidel R Speck T 《Integrative and comparative biology》2010,50(5):888-907
Plant and animal biomechanists have much in common. Although their frame of reference differs, they think about the natural world in similar ways. While researchers studying animals might explore airflow around flapping wings, the actuation of muscles in arms and legs, or the material properties of spider silk, researchers studying plants might explore the flow of water around fluttering seaweeds, the grasping ability of climbing vines, or the material properties of wood. Here we summarize recent studies of plant biomechanics highlighting several current research themes in the field: expulsion of high-speed reproductive projectiles, generation of slow movements by shrinking and swelling cell walls, effects of ontogenetic shifts in mechanical properties of stems, flexible reconfiguration and material properties of seaweeds under crashing waves, and the development of botanically-inspired commercial products. Our hope is that this synopsis will resonate with both plant and animal biologists, encourage cross-pollination across disciplines, and promote fruitful interdisciplinary collaborations in the future. 相似文献
78.
Mohammed A. Kader Sylvia Lindberg Thorsten Seidel Dortje Golldack Vladislav Yemelyanov 《Physiologia plantarum》2007,130(1):99-111
Perception of salt stress in plant cells induces a change in the free cytosolic Ca2+, [Ca2+]cyt, which transfers downstream reactions toward salt tolerance. Changes in cytosolic H+ concentration, [H+]cyt, are closely linked to the [Ca2+]cyt dynamics under various stress signals. In this study, salt‐induced changes in [Ca2+]cyt, and [H+]cyt and vacuolar [H+] concentrations were monitored in single protoplasts of rice (Oryza sativa L. indica cvs. Pokkali and BRRI Dhan29) by fluorescence microscopy. Changes in cytosolic [Ca2+] and [H+] were detected by use of the fluorescent dyes acetoxy methyl ester of calcium‐binding benzofuran and acetoxy methyl ester of 2′, 7′‐bis‐(2‐carboxyethyl)‐5‐(and‐6) carboxyfluorescein, respectively, and for vacuolar pH, fluorescent 6‐carboxyfluorescein and confocal microscopy were used. Addition of NaCl induced a higher increase in [Ca2+]cyt in the salt‐tolerant cv. Pokkali than in the salt‐sensitive cv. BRRI Dhan29. From inhibitor studies, we conclude that the internal stores appear to be the major source for [Ca2+]cyt increase in Pokkali, although the apoplast is more important in BRRI Dhan29. The [Ca2+]cyt measurements in rice also suggest that Na+ should be sensed inside the cytosol, before any increase in [Ca2+]cyt occurs. Moreover, our results with individual mesophyll protoplasts suggest that ionic stress causes an increase in [Ca2+]cyt and that osmotic stress sharply decreases [Ca2+]cyt in rice. The [pH]cyt was differently shifted in the two rice cultivars in response to salt stress and may be coupled to different activities of the H+‐ATPases. The changes in vacuolar pH were correlated with the expressional analysis of rice vacuolar H+‐ATPase in these two rice cultivars. 相似文献
79.
80.
Nucleic acid motors comprise a variety of structurally, mechanistically and functionally very different enzymes. These motor proteins have in common the ability to directionally move DNA or RNA, or to move along DNA or RNA using a chemical energy source such as ATP. Recently, it became possible to study the action of a single motor on single DNA or RNA molecules in real time; this has provided unprecedented insight into the behavior and mechanism of these motors. As a result, the past few years have witnessed an enormous increase in such single-molecule studies of a variety of different motor systems. Particular highlights have included the investigation of the sequence-dependent behavior and helical tracking of motors, and the attainment of the ultimate (i.e. single base pair) resolution, which enables the detection of individual single base motor steps. 相似文献