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61.
Suppression of oxidative phosphorylation confers resistance against bevacizumab in experimental glioma 下载免费PDF全文
Jule A. Eriksson Christina Wanka Michael C. Burger Hans Urban Ines Hartel Janusz von Renesse Patrick N. Harter Michel Mittelbronn Joachim P. Steinbach Johannes Rieger 《Journal of neurochemistry》2018,144(4):421-430
62.
63.
Mark C. Urban David K. Skelly Denise Burchsted William Price Sarah Lowry 《Diversity & distributions》2006,12(4):337-350
Rapid urbanization throughout the world is expected to cause extensive loss of biodiversity in the upcoming decades. Disturbances associated with urbanization frequently operate over multiple spatial scales such that local species extirpations have been attributed both to localized habitat degradation and to regional changes in land use. Urbanization also may shape stream communities by restricting species dispersal within and among stream reaches. In this patch-dynamics view, anthropogenic disturbances and isolation jointly reduce stream biodiversity in urbanizing landscapes. We evaluated predictions of stream invertebrate community composition and abundance based on variation in environmental conditions at five distinct spatial scales: stream habitats, reaches, riparian corridors and watersheds and their spatial location within the larger three-river basin. Despite strong associations between biodiversity loss and human density in this study, local stream habitat and stream reach conditions were poor predictors of community patterns. Instead, local community diversity and abundance were more accurately predicted by riparian vegetation and watershed landscape structure. Spatial coordinates associated with instream distances provided better predictions of stream communities than any of the environmental data sets. Together, results suggest that urbanization in the study region was associated with reduced stream invertebrate diversity through the alteration of landscape vegetation structure and patch connectivity. These findings suggest that maintaining and restoring watershed vegetation corridors in urban landscapes will aid efforts to conserve freshwater biodiversity. 相似文献
64.
Memory CD8+ T cells protect dendritic cells from CTL killing 总被引:1,自引:0,他引:1
Watchmaker PB Urban JA Berk E Nakamura Y Mailliard RB Watkins SC van Ham SM Kalinski P 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(6):3857-3865
CD8(+) T cells have been shown to be capable of either suppressing or promoting immune responses. To reconcile these contrasting regulatory functions, we compared the ability of human effector and memory CD8(+) T cells to regulate survival and functions of dendritic cells (DC). We report that, in sharp contrast to the effector cells (CTLs) that kill DCs in a granzyme B- and perforin-dependent mechanism, memory CD8(+) T cells enhance the ability of DCs to produce IL-12 and to induce functional Th1 and CTL responses in naive CD4(+) and CD8(+) T cell populations. Moreover, memory CD8(+) T cells that release the DC-activating factor TNF-alpha before the release of cytotoxic granules induce DC expression of an endogenous granzyme B inhibitor PI-9 and protect DCs from CTL killing with similar efficacy as CD4(+) Th cells. The currently identified DC-protective function of memory CD8(+) T cells helps to explain the phenomenon of CD8(+) T cell memory, reduced dependence of recall responses on CD4(+) T cell help, and the importance of delayed administration of booster doses of vaccines for the optimal outcome of immunization. 相似文献
65.
Purified and unpurified sodium channels from eel electroplax in planar lipid bilayers 总被引:3,自引:7,他引:3 下载免费PDF全文
Highly purified sodium channel protein from the electric eel, Electrophorus electricus, was reconstituted into liposomes and incorporated into planar bilayers made from neutral phospholipids dissolved in decane. The purest sodium channel preparations consisted of only the large, 260-kD tetrodotoxin (TTX)-binding polypeptide. For all preparations, batrachotoxin (BTX) induced long-lived single-channel currents (25 pS at 500 mM NaCl) that showed voltage-dependent activation and were blocked by TTX. This block was also voltage dependent, with negative potentials increasing block. The permeability ratios were 4.7 for Na+:K+ and 1.6 for Na+:Li+. The midpoint for steady state activation occurred around -70 mV and did not shift significantly when the NaCl concentration was increased from 50 to 1,000 mM. Veratridine-induced single-channel currents were about half the size of those activated by BTX. Unpurified, nonsolubilized sodium channels from E. electricus membrane fragments were also incorporated into planar bilayers. There were no detectable differences in the characteristics of unpurified and purified sodium channels, although membrane stability was considerably higher when purified material was used. Thus, in the eel, the large, 260-kD polypeptide alone is sufficient to demonstrate single-channel activity like that observed for mammalian sodium channel preparations in which smaller subunits have been found. 相似文献
66.
Arabidopsis genes encoding mitochondrial type II NAD(P)H dehydrogenases have different evolutionary origin and show distinct responses to light 下载免费PDF全文
Michalecka AM Svensson AS Johansson FI Agius SC Johanson U Brennicke A Binder S Rasmusson AG 《Plant physiology》2003,133(2):642-652
In addition to proton-pumping complex I, plant mitochondria contain several type II NAD(P)H dehydrogenases in the electron transport chain. The extra enzymes allow the nonenergy-conserving electron transfer from cytoplasmic and matrix NAD(P)H to ubiquinone. We have investigated the type II NAD(P)H dehydrogenase gene families in Arabidopsis. This model plant contains two and four genes closely related to potato (Solanum tuberosum) genes nda1 and ndb1, respectively. A novel homolog, termed ndc1, with a lower but significant similarity to potato nda1 and ndb1, is also present. All genes are expressed in several organs of the plant. Among the nda genes, expression of nda1, but not nda2, is dependent on light and circadian regulation, suggesting separate roles in photosynthesis-associated and other respiratory NADH oxidation. Genes from all three gene families encode proteins exclusively targeted to mitochondria, as revealed by expression of green fluorescent fusion proteins and by western blotting of fractionated cells. Phylogenetic analysis indicates that ndc1 affiliates with cyanobacterial type II NADH dehydrogenase genes, suggesting that this gene entered the eukaryotic cell via the chloroplast progenitor. The ndc1 should then have been transferred to the nucleus and acquired a signal for mitochondrial targeting of the protein product. Although they are of different origin, the nda, ndb, and ndc genes carry an identical intron position. 相似文献
67.
Adam S. Giermasz Julie A. Urban Yutaro Nakamura Payal Watchmaker Rachel L. Cumberland William Gooding Pawel Kalinski 《Cancer immunology, immunotherapy : CII》2009,58(8):1329-1336
While multiple pathways of dendritic cell (DC) maturation result in transient production of IL-12, fully mature DCs show reduced
ability to produce IL-12p70 upon a subsequent interaction with Ag-specific T cells, limiting their in vivo performance as
vaccines. Such “DC exhaustion” can be prevented by the presence of IFNγ during the maturation of human DCs (type-1-polarization),
resulting in improved induction of tumor-specific Th1 and CTL responses in vitro. Here, we show that type-1 polarization of
mouse DCs strongly enhances their ability to induce CTL responses against a model tumor antigen, OVA, in vivo, promoting the
induction of protective immunity against OVA-expressing EG7 lymphoma. Interestingly, in contrast to the human system, the
induction of mouse DC1s requires the participation of IL-4, a nominal Th2-inducing cytokine. The current data help to explain
the previously reported Th1-driving and anti-tumor activities of IL-4, and demonstrate that type-1 polarization increases
in vivo activity of DC-based vaccines.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Adam S. Giermasz and Julie A. Urban contributed equally to this work. 相似文献
68.
Valentina Millarte Gaelle Boncompain Kerstin Tillmann Franck Perez Elizabeth Sztul Hesso Farhan 《Molecular biology of the cell》2015,26(12):2263-2278
The role of early secretory trafficking in the regulation of cell motility remains incompletely understood. Here we used a small interfering RNA screen to monitor the effects on structure of the Golgi apparatus and cell migration. Two major Golgi phenotypes were observed—fragmented and small Golgi. The latter exhibited a stronger correlation with a defect in cell migration. Among the small Golgi hits, we focused on phospholipase C γ1 (PLCγ1). We show that PLCγ1 regulates Golgi structure and cell migration independently of its catalytic activity but in a manner that depends on interaction with the tethering protein p115. PLCγ1 regulates the dynamics of p115 in the early secretory pathway, thereby controlling trafficking from the endoplasmic reticulum to the Golgi. Our results uncover a new function of PLCγ1 that is independent of its catalytic function and link early secretory trafficking to the regulation of cell migration. 相似文献
69.
The opportunistic human fungal pathogen Candida albicans encounters diverse environmental stresses when it is in contact with its host. When colonizing and invading human tissues, C. albicans is exposed to ROS (reactive oxygen species) and RNIs (reactive nitrogen intermediates). ROS and RNIs are generated in the first line of host defence by phagocytic cells such as macrophages and neutrophils. In order to escape these host-induced oxidative and nitrosative stresses, C. albicans has developed various detoxification mechanisms. One such mechanism is the detoxification of NO (nitric oxide) to nitrate by the flavohaemoglobin enzyme CaYhb1. Members of the haemoglobin superfamily are highly conserved and are found in archaea, eukaryotes and bacteria. Flavohaemoglobins have a dioxygenase activity [NOD (NO dioxygenase domain)] and contain three domains: a globin domain, an FAD-binding domain and an NAD(P)-binding domain. In the present paper, we examine the nitrosative stress response in three fungal models: the pathogenic yeast C. albicans, the benign budding yeast Saccharomyces cerevisiae and the benign fission yeast Schizosaccharomyces pombe. We compare their enzymatic and non-enzymatic NO and RNI detoxification mechanisms and summarize fungal responses to nitrosative stress. 相似文献