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排序方式: 共有310条查询结果,搜索用时 31 毫秒
41.
Bazhin AV Schadendorf D Owen RW Zernii EY Philippov PP Eichmüller SB 《Molecular cancer research : MCR》2008,6(1):110-118
Proteins involved in the visual signaling cascade show light-dependent expression levels in photoreceptor cells. Recently, these proteins have been described to be expressed in neuroectodermal tumors and to function as cancer-retina antigens. Here, we show that light can down-regulate gene expression of rhodopsin, transducin, and cyclic guanosine 3',5'-monophosphate phosphodiesterase 6 (PDE6) and up-regulate guanylyl cyclase 1, recoverin, and arrestin in human melanoma cells in vitro, comparable to physiologic changes earlier observed in photoreceptor cells. Similar modulation can be detected at the protein level in melanoma cells except for no changes in PDE6 protein levels. Two regulatory pathways have been identified: Sp1/Sp3/Sp4 proteins for rhodopsin and PDE6, and mitogen-activated protein kinases for recoverin and arrestin. The visual cascade and retinoic acid as its derivate do not play any role in this process. Putative explanations for light-dependent modulation of cancer-retina antigen expression in melanoma cells are discussed. 相似文献
42.
Martina Hrušková-Martišová Stano Pekár Alexandr Gromov 《Journal of Insect Behavior》2008,21(5):440-449
Stridulation in solifuges has not been investigated yet. We performed a comparative analysis of the stridulatory organs and
sounds produced by juveniles of various developmental stages and adults (both sexes) of Galeodes caspius subfuscus Birula. The stridulatory organ is of similar morphology in all developmental stages. The sound that they produced was a broad
frequency hissing, composed of one or two chirps with maximum at 2.4 kHz. The intensity of the sound was found to increase
with body size. Otherwise, no differences were observed between stridulation in juvenile, male and female individuals. Therefore,
we suggest that the stridulation in solifuges has primarily a defensive role. As solifuges are neither venomous nor unpalatable,
they might imitate an accoustically aposematic organism that shares the same habitat and has similar circadian activity, e.g.
vipers. It may also have an intraspecific function in reduction of cannibalistic tendencies. 相似文献
43.
Annette Baeuerlein Stefanie Ackermann Alexandr Parlesak 《Microbiology and immunology》2009,53(4):241-250
The goal of the current study was to clarify whether commercially available probiotics induce greater trans-epithelial activation of human leukocytes than do commensal, food-derived and pathogenic bacteria and to identify the compounds responsible for this activation. Eleven different bacterial strains, and some of their pathogen-associated molecular patterns, were incubated apically on a confluent layer of intestinal epithelial cells (Caco-2), which were basolaterally co-cultured with human mononuclear leukocytes. Only Gram-negative bacteria having Enterobacteriaceae -type endotoxin (commensal Escherichia coli K12, probiotic E. coli Nissle, EPEC) induced basolateral production of TNF-α, IFN-γ, IL 6, 8, and 10. Gram-positive probiotics ( Lactobacillus spp. and Bifidobacterium spp. ) had virtually no effect. In addition, commensals ( Enterococcus faecalis , Bacteroides vulgatus ) and food fermenters ( Lactobacillus spp. ) did not stimulate leukocytes transepithelially. Endotoxin from E. coli and Salmonella enterica Typhimurium induced comparable transepithelial stimulation of leukocytes, but not endotoxin from B. vulgatus or lipoteichoic acid from E. faecalis . Endotoxin-binding agents (polymyxin, colistin) completely abrogated transepithelial activation of leukocytes. Enterobacteriaceae -type endotoxin is a crucial factor in transepithelial stimulation of leukocytes, regardless of whether it is produced by probiotics or other bacteria. Hence, transepithelial stimulation of leukocytes' innate immune response seems to not be linked to the health-promoting effects of probiotics. 相似文献
44.
Jakub Novotný Kateřina Pospěchová Alexandr Hrabálek Robert Čáp Kateřina Vávrová 《Bioorganic & medicinal chemistry letters》2009,19(24):6975-6977
Topical skin lipid supplementation may provide opportunities for controlling ceramide (Cer) deficiency in skin diseases such as atopic dermatitis or psoriasis. Here we describe the synthesis of a long-chain 7-nitrobenzo[c][1,2,5]oxadiazol-4-yl (NBD)-labeled Cer and its different penetration through human skin compared to widely used short-chain fluorescent Cer tools. 相似文献
45.
Janůšová B Zbytovská J Lorenc P Vavrysová H Palát K Hrabálek A Vávrová K 《Biochimica et biophysica acta》2011,1811(3):129-137
Stratum corneum ceramides play an essential role in the barrier properties of skin. However, their structure-activity relationships are poorly understood. We investigated the effects of acyl chain length in the non-hydroxy acyl sphingosine type (NS) ceramides on the skin permeability and their thermotropic phase behavior. Neither the long- to medium-chain ceramides (8-24 C) nor free sphingosine produced any changes of the skin barrier function. In contrast, the short-chain ceramides decreased skin electrical impedance and increased skin permeability for two marker drugs, theophylline and indomethacin, with maxima in the 4-6C acyl ceramides. The thermotropic phase behavior of pure ceramides and model stratum corneum lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesterol sulfate was studied by differential scanning calorimetry and infrared spectroscopy. Differences in thermotropic phase behavior of these lipids were found: those ceramides that had the greatest impact on the skin barrier properties displayed the lowest phase transitions and formed the least dense model stratum corneum lipid membranes at 32°C. In conclusion, the long hydrophobic chains in the NS-type ceramides are essential for maintaining the skin barrier function. However, this ability is not shared by their short-chain counterparts despite their having the same polar head structure and hydrogen bonding ability. 相似文献
46.
Antonov AS Kalinovsky AI Dmitrenok PS Kalinin VI Stonik VA Mollo E Cimino G 《Carbohydrate research》2011,346(14):2182-2192
Seven new triterpene glycosides, erylosides R1 (1), T1 (3), T2 (4), T3 (5), T4 (6), T5 (7), and T6 (8) along with the known formoside (2) were isolated from the sponge Erylus formosus collected along the Caribbean coast of Mexico. Glycoside 1 was determined as a trisaccharide, glycoside 2 as a tetrasaccharide while glycosides 3–8 were hexasaccharide. Their carbohydrate chains were unprecedented and have never been found in oligosaccharides from other biological sources, except Erylus spp. Three carbohydrate chains in the glycosides 3 and 6, 4 and 7, 5 and 8 correspondingly are new. The glycosides 1–5 have penasterol as aglycone while glycosides 6–8 proved to be glycoconjugates of 24-methylene-14-carboxy-lanost-8(9)-en-3β-ol. 相似文献
47.
Viktor Umansky Ivan Shevchenko Alexandr V. Bazhin Jochen Utikal 《Cancer immunology, immunotherapy : CII》2014,63(10):1073-1080
Malignant melanoma is characterized by the development of chronic inflammation in the tumor microenvironment, which leads to a strong immunosuppression associated with a rapid tumor progression. Adenosine is considered as one of the main immunosuppressive factors in the tumor environment. It is produced via enzymatic hydrolysis of extracellular ATP by ectonucleotidases CD39 and CD73 localized on cell surface. Using the ret transgenic mouse melanoma model that closely mimics human melanoma, we demonstrated an increased frequency of ectonucleotidase-positive myeloid-derived suppressor cells (MDSCs) in melanoma lesions and lymphoid organs. Furthermore, we observed that conventional CD4+FoxP3? and CD8+ T cells infiltrating melanoma lesions of ret transgenic mice were distinctly enriched in the CD39+CD73+ subpopulation that co-expressed also PD-1. Ectonucleotidase expression was also up-regulated in CD4+ and CD8+ T cells upon activation. In addition, these ectoenzymes were largely found to be expressed on memory T cell compartment (in particular, on effector memory cells). Our data suggest that extracellular adenosine produced by regulatory T cells (Tregs) and MDSCs can suppress T cell effector functions through paracrine signaling. Another mechanism involves its production also by effector T cells and an inhibition of their anti-tumor reactivity via autocrine signaling as a part of the negative feedback loop. This mode of adenosine signaling could be also used by Tregs and MDSCs to enhance their immunosuppressive activity. 相似文献
48.
49.
Four new species of Hymenoptera are described from the Early Cretaceous (Lower Barremian) lithographic limestones of the Sierra del Montsec (Lérida Province, NE Spain):Prosyntexis montsecensis n. sp. (Sepulcidae),Manlaya lacabrua n. sp. (Gasteruptiidae),Meiagaster cretaceus n. gen., n. sp. (Bethylonymidae),Angarosphex lithographicus n. sp. (Sphecidae). The Spanish assemblage extends our knowledge of the distribution of the Lower Cretaceous hymenopteran fauna and will throw light on its character in a probably dry environment with seasonal rainfall. 相似文献
50.
Svitlana Chernii Mykhaylo Losytskyy Anna Kelm Alexandr Gorski Iryna Tretyakova Sergiy Yarmoluk Victor Chernii Vladyslava Kovalska 《Journal of molecular recognition : JMR》2020,33(1)
Amyloid fibrils are rigid β‐pleated protein aggregates that are connected with series of harmful diseases and at the same time are promising as base for novel nanomaterials. Thus, design of compounds able to inhibit or redirect those aggregates formation is important both for the biomedical aims and for nanotechnology applications. Here, we studied the effect of tetraphenylporphyrins (metal free, their Cu and Pd complexes, and those functionalized by carboxy and amino groups on periphery) on insulin amyloid self‐assembling. The strongest impact on insulin aggregation was demonstrated by a metal‐free porphyrin bearing four carboxy groups. This compound strongly suppresses insulin aggregation (about 88% reduction in amyloid‐sensitive probe emission) inducing formation of fibrils with the length close to this of free insulin (1.7 ± 0.6 μm as compared with 1.4 ± 0.4 μm, respectively) with an essentially reduced tendency to lateral aggregation. Contrarily, the presence of tetraphenylporphyrin containing four amino groups only slightly affects fibrils' morphology and makes weaker impact on insulin aggregation yield (about 44% reduction). This is explained by the ability of aromatic carboxy groups of 5,10,15,20‐(tetra‐4‐carboxyphenyl)porphyrin to interact with complementary protein‐binding groups and thus stabilize the supramolecular complex. For 5,10,15,20‐(tetra‐4‐aminophenyl)porphyrin, full protonation takes place in acidic medium of protein aggregation reaction; this results in the high positive charge of TPPN4 (equal or close to +6) and hence higher contribution of coulombic repulsion to interaction of TPPN4 with insulin. One more possible mechanism of the lower inhibition effect of TPPN4 as compared with TPPC4 could be the more restricted possibility of the former as compared with the latter to form H bonds with insulin groups. It was also shown that metal‐free, Pd‐containing, and Cu‐containing tetraphenylporphyrins without peripheral substituents make almost the same impact on the protein self‐assembling. We suppose this to be due to coordination saturation of these metal atoms. 相似文献