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181.
Pettersson Stolk, S., Holmer, L. E. and Caron, J ‐B. 2010. First record of the brachiopod Lingulella waptaensis with pedicle from the Middle Cambrian Burgess Shale. —Acta Zoologica (Stockholm) 91 : 150–162 The organophosphatic shells of linguloid brachiopods are a common component of normal Cambrian–Ordovician shelly assemblages. Preservation of linguloid soft‐part anatomy, however, is extremely rare, and restricted to a few species in Lower Cambrian Konservat Lagerstätten. Such remarkable occurrences provide unique insights into the biology and ecology of early linguloids that are not available from the study of shells alone. Based on its shells, Lingulella waptaensis Walcott, was originally described in 1924 from the Middle Cambrian Burgess Shale but despite the widespread occurrence of soft‐part preservation associated with fossils from the same levels, no preserved soft parts have been reported. Lingulella waptaensis is restudied herein based on 396 specimens collected by Royal Ontario Museum field parties from the Greater Phyllopod Bed (Walcott Quarry Shale Member, British Columbia). The new specimens, including three with exceptional preservation of the pedicle, were collected in situ in discrete obrution beds. Census counts show that L. waptaensis is rare but recurrent in the Greater Phyllopod Bed, suggesting that this species might have been generalist. The wrinkled pedicle protruded posteriorly between the valves, was composed of a central coelomic space, and was slender and flexible enough to be tightly folded, suggesting a thin chitinous cuticle and underlying muscular layers. The nearly circular shell and the long, slender and highly flexible pedicle suggest that L. waptaensis lived epifaunally, probably attached to the substrate. Vertical cross‐sections of the shells show that L. waptaensis possessed a virgose secondary layer, which has previously only been known from Devonian to Recent members of the Family Lingulidae. 相似文献
182.
Sarah R. Elkin Nathaniel W. Oswald Dana K. Reed Marcel Mettlen John B. MacMillan Sandra L. Schmid 《Traffic (Copenhagen, Denmark)》2016,17(10):1139-1149
Ikarugamycin (IKA) is a previously discovered antibiotic, which has been shown to inhibit the uptake of oxidized low‐density lipoproteins in macrophages. Furthermore, several groups have previously used IKA to inhibit clathrin‐mediated endocytosis (CME) in plant cell lines. However, detailed characterization of IKA has yet to be performed. Consequently, we performed biochemistry and microscopy experiments to further characterize the effects of IKA on CME. We show that IKA has an IC50 of 2.7 μm in H1299 cells and acutely inhibits CME, but not other endocytic pathways, in a panel of cell lines. Although long‐term incubation with IKA has cytotoxic effects, the short‐term inhibitory effects on CME are reversible. Thus, IKA can be a useful tool for probing routes of endocytic trafficking. 相似文献
183.
Complementary expression of IGF-II and IGFBP-5 during anterior pituitary development 总被引:1,自引:0,他引:1
The specification of the five individual hormone-secreting cell types in the anterior pituitary requires a series of sequential cell fate decisions. We have immortalized cells at several stages along this pathway of pituitary differentiation. Here, we present analysis of differences in gene expression between an anterior pituitary precursor cell line, alphaT1-1, and an immature gonadotrope cell line, alphaT3-1, identified by using cDNA subtraction. Messenger RNA expression of members of the insulin-like growth factor signaling system, IGF-II and IGFBP-5, was found in the alphaT1-1 precursor cell line, but not in the more differentiated cell line, alphaT3-1. This inferred stage specificity was confirmed in the mouse embryo by using in situ hybridization on embryonic days e10.5 through e18.5. Expression of IGF-II and IGFBP-5 mRNAs was both temporally and spatially regulated during pituitary development. IGF-II was highly expressed in the epithelium surrounding Rathke's pouch at e10.5, while IGFBP-5 expression was restricted to the adjacent oral epithelium. At e11.5 (represented by alphaT1-1), IGF-II was expressed throughout the pouch, but was coexpressed with IGFBP-5 and alpha-subunit in the ventral portion of the pouch epithelium. On e12.5, the two mRNAs were expressed in opposing dorsoventral (IGF-II) and ventrodorsal (IGFBP-5) patterns, with IGF-II excluded from the rostral, alpha-subunit-expressing region. A decrease of both mRNAs was observed at e14.5 (equivalent to alphaT3-1), with IGF-II levels low and IGFBP-5 concentrated in the anterior pituitary rostral tip. These findings suggest that the timing of IGF-II expression and regulation of its accessibility by IGFBP-5 may play a role in anterior pituitary differentiation, survival, and/or proliferation. 相似文献
184.
Molecular characterization of DSR-E,an alpha-1,2 linkage-synthesizing dextransucrase with two catalytic domains 下载免费PDF全文
Bozonnet S Dols-Laffargue M Fabre E Pizzut S Remaud-Simeon M Monsan P Willemot RM 《Journal of bacteriology》2002,184(20):5753-5761
A novel Leuconostoc mesenteroides NRRL B-1299 dextransucrase gene, dsrE, was isolated, sequenced, and cloned in Escherichia coli, and the recombinant enzyme was shown to be an original glucansucrase which catalyses the synthesis of alpha-1,6 and alpha-1,2 linkages. The nucleotide sequence of the dsrE gene consists of an open reading frame of 8,508 bp coding for a 2,835-amino-acid protein with a molecular mass of 313,267 Da. This is twice the average mass of the glucosyltransferases (GTFs) known so far, which is consistent with the presence of an additional catalytic domain located at the carboxy terminus of the protein and of a central glucan-binding domain, which is also significantly longer than in other glucansucrases. From sequence comparison with family 70 and alpha-amylase enzymes, crucial amino acids involved in the catalytic mechanism were identified, and several original sequences located at some highly conserved regions in GTFs were observed in the second catalytic domain. 相似文献
185.
Michele Carbone Erin G. Flores Mitsuru Emi Todd A. Johnson Tatsuhiko Tsunoda Dusty Behner Harriet Hoffman Mary Hesdorffer Masaki Nasu Andrea Napolitano Amy Powers Michael Minaai Francine Baumann Peter Bryant-Greenwood Olivia Lauk Michaela B. Kirschner Walter Weder Isabelle Opitz Harvey I. Pass Giovanni Gaudino Sandra Pastorino Haining Yang 《PLoS genetics》2015,11(12)
We recently discovered an inherited cancer syndrome caused by BRCA1-Associated Protein 1 (BAP1) germline mutations, with high incidence of mesothelioma, uveal melanoma and other cancers and very high penetrance by age 55. To identify families with the BAP1 cancer syndrome, we screened patients with family histories of multiple mesotheliomas and melanomas and/or multiple cancers. We identified four families that shared an identical BAP1 mutation: they lived across the US and did not appear to be related. By combining family histories, molecular genetics, and genealogical approaches, we uncovered a BAP1 cancer syndrome kindred of ~80,000 descendants with a core of 106 individuals, whose members descend from a couple born in Germany in the early 1700s who immigrated to North America. Their descendants spread throughout the country with mutation carriers affected by multiple malignancies. Our data show that, once a proband is identified, extended analyses of these kindreds, using genomic and genealogical studies to identify the most recent common ancestor, allow investigators to uncover additional branches of the family that may carry BAP1 mutations. Using this knowledge, we have identified new branches of this family carrying BAP1 mutations. We have also implemented early-detection strategies that help identify cancers at early-stage, when they can be cured (melanomas) or are more susceptible to therapy (MM and other malignancies). 相似文献
186.
187.
Casadesus G Moreira PI Nunomura A Siedlak SL Bligh-Glover W Balraj E Petot G Smith MA Perry G 《Neurochemical research》2007,32(4-5):717-722
Metabolic alterations are a key player involved in the onset of Alzheimer disease pathophysiology and, in this review, we
focus on diet, metabolic rate, and neuronal size differences that have all been shown to play etiological and pathological
roles in Alzheimer disease. Specifically, one of the earliest manifestations of brain metabolic depression in these patients
is a sustained high caloric intake meaning that general diet is an important factor to take in account. Moreover, atrophy
in the vasculature and a reduced glucose transporter activity for the vessels is also a common feature in Alzheimer disease.
Finally, the overall size of neurons is larger in cases of Alzheimer disease than that of age-matched controls and, in individuals
with Alzheimer disease, neuronal size inversely correlates with disease duration and positively associates with oxidative
stress. Overall, clarifying cellular and molecular manifestations involved in metabolic alterations may contribute to a better
understanding of early Alzheimer disease pathophysiology.
Special issue dedicated to John P. Blass.
Gemma Casadesus and Paula I. Moreira contributed equally to this paper. Aspects of this paper were previously presented in
Neurochemical Research
28, 1549–1552, 2003 and the Journal of Alzheimer’s Disease
1, 203–206, 1999 and were used here with permission. 相似文献
188.
Real-time PCR and northern hybridisations were used to quantify bacterial populations in the large gut of infants. PCR primers for rapid, sensitive, high throughput detection of bifidobacteria, bacteroides, sulphate-reducing bacteria and Enterococcus faecalis, based on analysis of 16S rRNA genes were used. Bacterial populations were analysed in faeces from 40 infants aged 0-6, 7-12 and 13-24 months. The effects of breast versus bottle feeding was also investigated. Real-time PCR indicated that bacteroides and desulfovibrio numbers increased markedly in the 7-12 and 13-24 month age groups, and that the reverse occurred with Ent. faecalis. With the exception of desulfovibrios, this was seen with northern hybridisations, which also showed increased colonisation by the Clostridium coccoides group and Faecalibacterium prausnitzii after 6 months. Both methodologies indicated increased bifidobacteria in breast-fed babies, and higher levels of desulfovibrios in bottle-fed children. 相似文献
189.
Thymoquinone (TQ; 1 ) is a weak anticancer constituent of black seed oil. Derivatives bearing terpene‐terminated 6‐alkyl residues were tested in cells of human HL‐60 leukemia, 518A2 melanoma, multidrug‐resistant KB‐V1/Vbl cervix, and MCF‐7/Topo breast carcinomas, as well as in non‐malignant human foreskin fibroblasts. Derivatives with a short four‐atom spacer between quinone and cyclic monoterpene moieties were more antiproliferative than analogues with longer spacers. 6‐(Menthoxybutyryl)thymoquinone ( 3a ) exhibited single‐digit micromolar IC50 (72 h) values in all four cell lines. It was seven times more active than TQ ( 1 ) in 518A2 melanoma cells and four times in KB‐V1/Vbl cervix carcinoma cells, while only half as toxic in the fibroblasts. Compound 3a was also not a substrate for the P‐gp and BCRP drug transporters of the resistant cancer cells. The caryophyllyl and germacryl conjugates 3e and 3f specifically inhibited the growth of the resistant MCF‐7 breast carcinoma cells. Conjugation of TQ with the triterpene betulinic acid via the OH group as in 3g led to a loss in activity, while conjugation via the carboxylic acid afforded compound 4 with nanomolar IC50 (72 h) activity against HL‐60 cells. All anticancer‐active derivatives of TQ ( 1 ) induced apoptosis associated with DNA laddering, a decrease in mitochondrial membrane potential and a slight increase in reactive oxygen species. 相似文献
190.
Members of the nitrite-oxidizing genus Nitrospira are most likely responsible for the second step of nitrification, the conversion of nitrite (NO2−) to nitrate (NO3−), within various sponges. We succeeded in obtaining an enrichment culture of Nitrospira derived from the mesohyl of the marine sponge Aplysina aerophoba using a traditional cultivation approach. Electron microscopy gave first evidence of the shape and ultrastructure of this novel marine Nitrospira-like bacterium (culture Aa01). We characterized these bacteria physiologically with regard to optimal incubation conditions, especially the temperature and substrate range in comparison to other Nitrospira cultures. Best growth was obtained at temperatures between 28°C and 30°C in mineral medium with 70% North Sea water and a substrate concentration of 0.5 mM nitrite under microaerophilic conditions. The Nitrospira culture Aa01 is very sensitive against nitrite, because concentrations higher than 1.5 mM resulted in a complete inhibition of growth. Sequence analyses of the 16S rRNA gene revealed that the novel Nitrospira-like bacterium is separated from the sponge-specific subcluster and falls together with an environmental clone from Mediterranean sediments (98.6% similarity). The next taxonomically described species Nitrospira marina is only distantly related, with 94.6% sequence similarity, and therefore the culture Aa01 represents a novel species of nitrite-oxidizing bacteria.Numerous sponges have the capacity to accommodate large amounts of diverse microbes and represent significant sources for bioactive natural compounds (13). Many marine invertebrates excrete ammonium as a metabolic waste product (9), and the excretion of nitrite and nitrate has been taken as primary evidence that nitrifiers are active in these animals (10). By modulation of their pumping, sponges are a suitable habitat not only for aerobic microbes but also for anaerobic microbes. Accordingly, Hoffmann et al. (19) were able to detect major microbial pathways of the nitrogen cycle in the sponge Geodia barretti, including nitrification, the anammox process, and denitrification.Nitrification involves the biological oxidation of ammonia (NH3) to nitrite (NO2−) and further to nitrate (NO3−) for energy purposes. It is of fundamental importance for the global nitrogen cycle in aquatic and terrestrial habitats. Nitrification is catalyzed by two phylogenetically distinct groups of microorganisms: in the first step, ammonia-oxidizing bacteria and archaea (AOB and AOA) take part in the oxidation of ammonia to nitrite, and in the second step nitrite-oxidizing bacteria (NOB) convert nitrite to nitrate (38).Nitrite has a central position in the nitrogen cycle, connecting aerobic and anaerobic pathways. Nitrite-oxidizing bacteria play a major role in removing nitrite from the environment because it is toxic for living organisms (31). Based on morphological characteristics, NOB have been divided into five genera. This classification also reflects the phylogenetic diversity of NOB, which includes Nitrobacter and Nitrococcus (Alpha- and Gammaproteobacteria), Nitrospina (putative Deltaproteobacteria), and the candidate genus “Candidatus Nitrotoga” (Betaproteobacteria) (2). The genus Nitrospira is more distantly related to the other known NOB because it is part of its own deep-branching bacterial phylum Nitrospirae. Marine species are present in all genera of NOB except in the newly identified genus “Candidatus Nitrotoga.”As all known nitrifying prokaryotes are slow growing and hard to maintain, their enrichment and isolation from environmental samples is difficult. Most physiological studies have been performed with pure cultures of a few “model” nitrifiers, in particular AOB related to the genus Nitrosomonas and NOB of the genus Nitrobacter. For the genus Nitrospira there are only four pure cultures available: the marine species Nitrospira marina (37), Nitrospira moscoviensis (12), “Candidatus Nitrospira bockiana” (25), and Nitrospira calida (E. Lebedeva, personal communication).Sponges of the family Aplysinidae contain large amounts of bacteria embedded within the sponge tissue matrix (15). For example, the biomass of Aplysina aerophoba consists of up to 40% bacteria (36). These sponges are able to differentiate between food bacteria and their own bacterial symbionts (41). Investigations of the diversity of sponge-associated bacteria, including different genetic and also cultivation approaches, have been made with several specimens (15, 16, 39). In terms of nitrification, Hentschel et al. (17) gave first evidence for the presence of nitrite oxidizers, and it has been verified that sponges harbor AOB and AOA (8). Most of the recognized NOB in sponges are Nitrospira-like bacteria (17, 32, 35), although in the beginning, there were further hints to 16S rRNA sequences, which are most closely related to Nitrospina gracilis (17). However, as these sequences were found only once, it could be assumed that Nitrospira is the main nitrite oxidizer in this environment. Nitrospira-like bacteria are deemed to be recalcitrant and fastidious, and they are easily overgrown by other bacteria under suboptimal conditions. Despite these limitations in the laboratory, Nitrospira was determined to be the most important nitrite oxidizer during wastewater treatment (21, 33), in aquaculture biofilters (14) and in freshwater systems (20, 29).Identification of sponge-associated microorganisms has been performed largely with culture-independent methods, which are 16S rRNA gene based (denaturing gradient gel electrophoresis [DGGE], terminal restriction fragment-length polymorphism [TRFLP]) or visual (fluorescence in situ hybridization [FISH], electron microscopy) (8, 11). Nevertheless, the cultivation of microorganisms is still essential for the investigation of their physiological potential and function in the environment. Information about physiological characteristics helps us to understand the metabolism and possible nutritional interactions of nitrifiers with the host sponge (8).This is the first report about cultivation of nitrifying bacteria originating from a marine sponge. We obtained a nitrite-oxidizing enrichment culture of a Nitrospira-like bacterium derived from Aplysina aerophoba, characterized it phylogenetically, and analyzed the most important physiological features. 相似文献