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981.
Rike Diderrich Michael Kock Manuel Maestre-Reyna Petra Keller Holger Steuber Steffen Rupp Lars-Oliver Essen Hans-Ulrich M?sch 《The Journal of biological chemistry》2015,290(32):19597-19613
For host colonization, the human fungal pathogen Candida glabrata is known to utilize a large family of highly related surface-exposed cell wall proteins, the lectin-like epithelial adhesins (Epas). To reveal the structure-function relationships within the entire Epa family, we have performed a large scale functional analysis of the adhesion (A) domains of 17 Epa paralogs in combination with three-dimensional structural studies of selected members with cognate ligands. Our study shows that most EpaA domains exert lectin-like functions and together recognize a wide variety of glycans with terminal galactosides for conferring epithelial cell adhesion. We further identify several conserved and variable structural features within the diverse Epa ligand binding pockets, which affect affinity and specificity. These features rationalize why mere phylogenetic relationships within the Epa family are weak indicators for functional classification and explain how Epa-like adhesins have evolved in C. glabrata and related fungal species. 相似文献
982.
Tadahiro Suenaga Maki Matsumoto Fuminori Arisawa Masako Kohyama Kouyuki Hirayasu Yasuko Mori Hisashi Arase 《The Journal of biological chemistry》2015,290(32):19833-19843
Varicella-zoster virus (VZV) is a member of the human Herpesvirus family that causes varicella (chicken pox) and zoster (shingles). VZV latently infects sensory ganglia and is also responsible for encephalomyelitis. Myelin-associated glycoprotein (MAG), a member of the sialic acid (SA)-binding immunoglobulin-like lectin family, is mainly expressed in neural tissues. VZV glycoprotein B (gB) associates with MAG and mediates membrane fusion during VZV entry into host cells. The SA requirements of MAG when associating with its ligands vary depending on the specific ligand, but it is unclear whether the SAs on gB are involved in the association with MAG. In this study, we found that SAs on gB are essential for the association with MAG as well as for membrane fusion during VZV infection. MAG with a point mutation in the SA-binding site did not bind to gB and did not mediate cell-cell fusion or VZV entry. Cell-cell fusion and VZV entry mediated by the gB-MAG interaction were blocked by sialidase treatment. N-glycosylation or O-glycosylation inhibitors also inhibited the fusion and entry mediated by gB-MAG interaction. Furthermore, gB with mutations in N-glycosylation sites, i.e. asparagine residues 557 and 686, did not associate with MAG, and the cell-cell fusion efficiency was low. Fusion between the viral envelope and cellular membrane is essential for host cell entry by herpesviruses. Therefore, these results suggest that SAs on gB play important roles in MAG-mediated VZV infection. 相似文献
983.
四种蕈菌凝集素的筛选及活性检测 总被引:1,自引:0,他引:1
以长刺猴、白平菇、毛尖蘑、滑菇四种蕈菌为材料,经硫酸铵沉淀、透析,得到蛋白质提取液,用不同类型的红细胞检测凝集活性(人的A型、B型、AB型、O型血,兔血、鸡血、蛤蟆血)。结果表明,长刺猴、白平菇、滑菇3种蕈菌的提取物中均含有凝集素,桦树蘑对兔红细胞凝集性最强。凝集活性可分别被一种或多种类型糖所抑制。同时它们均表现出较好的热稳定性及pH耐受性,金属离子对凝集素的影响也相当大。 相似文献
984.
Claessens A Van de Vijver K Van Bockstaele DR Wauters J Berneman ZN Van Marck E Merregaert J 《Cell biology international》2007,31(11):1323-1330
The C-type lectin family is a group of animal proteins which can be distinguished from other lectins by the presence of a Ca2+-dependent carbohydrate recognition domain (CRD) in their protein sequence. They are classified into 17 groups according to their domain architecture and have a wide variety of functions. The human chondrolectin gene encodes transmembrane (CHODL, CHODLf) and soluble proteins (CHODLDeltaE, CHODLfDeltaE) belonging to the family of C-type lectins because of the presence of one CRD domain in their N-terminal region. The CHODL splice variants (CHODLf, CHODLDeltaE and CHODLfDeltaE) are differentially expressed in T lymphocytes. The transmembrane-containing isoform CHODLf is localized in the ER-Golgi apparatus. CHODLDeltaE and CHODLfDeltaE are devoid of the transmembrane domain and terminate in QDEL, an ER retention signal. In this paper we have investigated the expression of the CHODLDeltaE/CHODLfDeltaE protein. This variant localizes in the late endoplasmic reticulum. We detected the protein in spleen and tonsils in a small population of lymphocytes. Moreover, the isoform seems to be differentially expressed in thymocytes and lymphocytes suggesting an important biological function during T cell development. 相似文献
985.
Lorena Bavia Pmela Dias Fontana Fernanda Bovo Aridine Reder C. de Souza Marcos Lúcio Corazza Iara Jose Messias‐Reason 《化学与生物多样性》2019,16(12)
The complement system participates in host defense by eliminating microorganisms and triggering inflammation. However, insufficient control or exacerbated complement activation contributes to inflammatory diseases. Since promising antioxidant and anti‐inflammatory activities have been identified in Arctium lappa L. extracts, this study aims to explore the effect of A. lappa extracts on the lectin pathway (LP) of complement activation. Four extracts were obtained by supercritical extraction using scCO2 with or without ethanol as co‐solvent, at different temperatures and pressures (E1: 2.2 mg/mL, E2: 2.6 mg/mL and E3: 2.0 mg/mL, E4: 1.5 mg/mL). To evaluate the effect of A. lappa extracts on the LP activation, an ELISA assay using mannose binding lectin pathway of complement was carried out with C4 detection. All extracts showed a concentration‐dependent inhibitory effect on the activation of complement by the LP. The following IC50 were observed for E1, E2, E3 and E4: 179.4 μg/mL, 74.69 μg/mL, 119.1 μg/mL and 72.19 μg/mL, respectively. Our results suggest that A. lappa extracts are potential candidates for the treatment of inflammatory disorders that are complement‐related. 相似文献
986.
Birch A. Nicholas E. Geoghegan Irene E. Majerus Michael E.N. McNicol James W. Hackett Christine A. Gatehouse Angharad M.R. Gatehouse John A. 《Molecular breeding : new strategies in plant improvement》1999,5(1):75-83
Transgenic crops genetically engineered for enhanced insect resistance should be compatible with other components of IPM for the pest resistance to be durable and effective. An experimental potato line was genetically engineered to express an anti-aphid plant protein (snowdrop lectin, GNA), and assessed for possible interactions of the insect resistance gene with a beneficial pest predator. These extended laboratory studies are the first to demonstrate adverse tri-trophic interactions involving a lectin- expressing transgenic crop, a target pest aphid and a beneficial aphidophagous predator. When adult 2-spot ladybirds (Adalia bipunctata[L.]) were fed for 12 days on peach-potato aphids (Myzus persicae Sulzer) colonising transgenic potatoes expressing GNA in leaves, ladybird fecundity, egg viability and longevity significantly decreased over the following 2–3 weeks. No acute toxicity due to the transgenic plants was observed, although female ladybird longevity was reduced by up to 51%. Adverse effects on ladybird reproduction, caused by eating peach-potato aphids from transgenic potatoes, were reversed after switching ladybirds to feeding on pea aphids from non-transgenic bean plants. These results demonstrate that expression of a lectin gene for insect resistance in a transgenic potato line can cause adverse effects to a predatory ladybird via aphids in its food chain. The significance of these potential ecological risks under field conditions need to be further evaluated. 相似文献
987.
稻胚凝集素基因的克隆,序列分析及表达 总被引:1,自引:0,他引:1
以水稻基因组DNA为模板,以特异引物经聚合酶链式反应方法扩增出稻胚凝集素基因并克隆到E.coli质粒pBluescriptSK(+)的SmaⅠ位点。序列分析表明,克隆到的基因片段大小为781bp,没有内含子,编码1条长227个氨基酸、分子量约23kD的肽链,其中N-端28个氨基酸是信号肽。与报道的稻胚凝集素cDNA序列进行顺序同源性比较,发现它们之间有很高的同源性(99.74%),其编码区第167 相似文献
988.
Akihiro Kawakubo Hiroyuki Makino Jun-ichi Ohnishi Hideo Hirohara Kanji Hori 《Journal of applied phycology》1999,11(2):149-156
We previously reported that the red alga Eucheuma serra contains large amounts of mitogenic isolectins (ESA-1 and ESA-2),
the hemagglutinating activities of which were strongly inhibited by glycoproteins bearing high mannose-type N-glycans. We
therefore further examined two other species, E. amakusaensis and E. cottonii. Several lectins were isolated easily by a combination
of extraction with aqueous ethanol, precipitation with cold ethanol, gel filtration, and ion exchange chromatography from
both species, respectively. The purified lectins were designated as EAA-1, EAA-2, EAA-3, ECA-1 and ECA-2 after the specific
names of both algae. The yields of EAAs and ECAs were as high as 2.8 and 2.7 mg g−1 of dry tissue, respectively, indicating that both species would also be good sources for high lectin yields. The five purified
lectins shared the same properties in hemagglutinating activity, mitogenic activity, and hemagglutination-inhibition test
in which glycoproteins bearing high mannose-type N-glycans were the most inhibitory. They also had almost identical molecular
weight and 20 N-terminal amino acid sequence to each other and to those of ESAs, and only differed in the isoelectric point,
indicating that they are isolectins to each other. The study thus demonstrated that several species of Eucheuma contain high
yields of lectins homologous between species, suggesting that the genus as a whole may be considered as a valuable source
of lectin proteins.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
989.
【目的】鉴定出一种新的亚洲玉米螟Ostrinia furnacalis (Guenée) C型凝集素(C-type lectin),并对其功能进行初步研究。【方法】通过生物信息学分析,从亚洲玉米螟转录组中筛选得到一个可能的C型凝集素基因,命名为CTL6。利用RT-PCR技术分析该基因在亚洲玉米螟不同龄期、不同组织及不同病原物诱导下的表达模式。借助原核及杆状病毒真核表达系统产生重组CTL6蛋白,并利用细菌凝集实验对其功能进行初步研究。【结果】CTL6基因cDNA全长序列为1 034 nt,其中完整开放阅读框为945 nt。推导的CTL6多肽序列包括314个氨基酸残基,N端含有由22个氨基酸残基组成的信号肽。CTL6成熟肽中含有两个串联的糖识别结构域,与烟草天蛾Manduca sexta的IML-2 (Immulectin-2)同源性最高。RT-PCR结果显示,CTL6在亚洲玉米螟5龄幼虫期转录水平最高,卵期其次,不同组织中则是在脂肪体中转录水平最高,呈诱导性表达。纯化的CTL6重组蛋白对大肠杆菌Escherichia coli具有一定的凝集作用。【结论】鉴定到的亚洲玉米螟CTL6是一种典型的C型凝集素,重组CTL6蛋白可能参与了亚洲玉米螟对病原菌的凝集作用。 相似文献
990.
Lipid extracts of whole uterine tissue from mice were examined by gas chromatography-mass spectrometry during days 2, 3, and 4 of pseudopregnancy (day 1 = copulatory plug) and following the artificial induction of the decidual cell reaction (DCR) on day 4. The range of lipids identified during pseudopregnancy and their percentage composition on day 2 included saturated fatty acids (SFA, 38%), monounsaturated fatty acids (MUFA, 20%), polyunsaturated fatty acids (PUFA, 17%), sterols (25%), long chain alcohols (0.12%), and alkylglycerols (0.11%). Of these, the main components were the fatty acids 16:0 (21%), 18:0 (14%), cis18:1n-9 (14%), 18:2n-6 (8.5%), and cholesterol (24%). Although only subtle changes in the composition of uterine lipids occurred through days 2 and 3 of pseudopregnancy, more substantial changes were detected on day 4, at a time when the uterus normally initiates its transient “window of receptivity.” Following induction of the DCR with the lectin Concanavalin A (Con A) at this time, even greater alterations in uterine lipid composition were observed. From 20 to 1,280 min post-Con A-treatment the percentage composition of SFA in the treated left uterine horn changed from 43% to 64%, sterols from 19% to 4%, PUFA from 15% to 10%, while MUFA remained unchanged at 23%. The lipid profile of the untreated right uterine horn of these animals was similar to that of the Con A-treated left uterine horn during the early stages. However, by 1,280 min substantial differences were observed, at a time corresponding with Con A-induced uterine growth. In contrast, differences in the lipid profile of Con A- and saline-treated uteri were observed at 320 min post-treatment, a time preceding Con A-induced uterine growth. Furthermore, the tissue concentration (nmol/mg dry weight) of SFA and sterols in uterine tissue decreased significantly following Con A treatment. The results suggest that uterine lipid changes are implicated in the development of uterine receptivity, and in the remodeling of uterine tissue for successful embryonic invasion and the establishment of pregnancy. © 1996 Wiley-Liss, Inc 相似文献