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151.
This paper discusses how to specify an observable high‐frequency model for a vector of time series sampled at high and low frequencies. To this end we first study how aggregation over time affects both the dynamic components of a time series and their observability, in a multivariate linear framework. We find that the basic dynamic components remain unchanged but some of them, mainly those related to the seasonal structure, become unobservable. Building on these results, we propose a structured specification method built on the idea that the models relating the variables in high and low sampling frequencies should be mutually consistent. After specifying a consistent and observable high‐frequency model, standard state‐space techniques provide an adequate framework for estimation, diagnostic checking, data interpolation and forecasting. An example using national accounting data illustrates the practical application of this method. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
152.
Marscher AP Jorstad SG Gómez JL Aller MF Teräsranta H Lister ML Stirling AM 《Nature》2002,417(6889):625-627
Accretion of gas onto black holes is thought to power the relativistic jets of material ejected from active galactic nuclei (AGN) and the 'microquasars' located in our Galaxy. In microquasars, superluminal radio-emitting features appear and propagate along the jet shortly after sudden decreases in the X-ray fluxes. This establishes a direct observational link between the black hole and the jet: the X-ray dip is probably caused by the disappearance of a section of the inner accretion disk as it falls past the event horizon, while the remainder of the disk section is ejected into the jet, creating the appearance of a superluminal bright spot. No such connection has hitherto been established for AGN, because of insufficient multi-frequency data. Here we report the results of three years of monitoring the X-ray and radio emission of the galaxy 3C120. As has been observed for microquasars, we find that dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. The mean time between X-ray dips appears to scale roughly with the mass of the black hole, although there are at present only a few data points. 相似文献
153.
Lennart Zabeau Cathy J. Jensen Sylvie Seeuws Koen Venken Annick Verhee Dominiek Catteeuw Geert van Loo Hui Chen Ken Walder Jacob Hollis Simon Foote Margaret J. Morris José Van der Heyden Frank Peelman Brian J. Oldfield Justin P. Rubio Dirk Elewaut Jan Tavernier 《Cellular and molecular life sciences : CMLS》2015,72(3):629-644
154.
155.
José L. Barbero 《Cellular and molecular life sciences : CMLS》2009,66(13):2025-2035
Cells have evolved to develop molecules and control mechanisms that guarantee correct chromosome segregation and ensure the
proper distribution of genetic material to daughter cells. In this sense, the establishment, maintenance, and removal of sister
chromatid cohesion is one of the most fascinating and dangerous processes in the life of a cell because errors in the control
of these processes frequently lead to cell death or aneuploidy. The main protagonist in this mechanism is a four-protein complex
denominated the cohesin complex. In the last 10 years, we have improved our understanding of the key players in the regulation
of sister chromatid cohesion during cell division in mitosis and meiosis. The last 2 years have seen an increase in evidence
showing that cohesins have important functions in non-dividing cells, revealing new, unexplored roles for these proteins in
the control of gene expression, development, and other essential cell functions in mammals. 相似文献
156.
Comino-Méndez I Gracia-Aznárez FJ Schiavi F Landa I Leandro-García LJ Letón R Honrado E Ramos-Medina R Caronia D Pita G Gómez-Graña A de Cubas AA Inglada-Pérez L Maliszewska A Taschin E Bobisse S Pica G Loli P Hernández-Lavado R Díaz JA Gómez-Morales M González-Neira A Roncador G Rodríguez-Antona C Benítez J Mannelli M Opocher G Robledo M Cascón A 《Nature genetics》2011,43(7):663-667
Hereditary pheochromocytoma (PCC) is often caused by germline mutations in one of nine susceptibility genes described to date, but there are familial cases without mutations in these known genes. We sequenced the exomes of three unrelated individuals with hereditary PCC (cases) and identified mutations in MAX, the MYC associated factor X gene. Absence of MAX protein in the tumors and loss of heterozygosity caused by uniparental disomy supported the involvement of MAX alterations in the disease. A follow-up study of a selected series of 59 cases with PCC identified five additional MAX mutations and suggested an association with malignant outcome and preferential paternal transmission of MAX mutations. The involvement of the MYC-MAX-MXD1 network in the development and progression of neural crest cell tumors is further supported by the lack of functional MAX in rat PCC (PC12) cells and by the amplification of MYCN in neuroblastoma and suggests that loss of MAX function is correlated with metastatic potential. 相似文献
157.
Emerging topics and new perspectives on HLA-G 总被引:1,自引:1,他引:0
Fainardi E Castellazzi M Stignani M Morandi F Sana G Gonzalez R Pistoia V Baricordi OR Sokal E Peña J 《Cellular and molecular life sciences : CMLS》2011,68(3):433-451
Following the Fifth International Conference on non-classical HLA-G antigens (HLA-G), held in Paris in July 2009, we selected
some topics which focus on emerging aspects in the setting of HLA-G functions. In particular, HLA-G molecules could play a
role in: (1) various inflammatory disorders, such as multiple sclerosis, intracerebral hemorrhage, gastrointestinal, skin
and rheumatic diseases, and asthma, where they may act as immunoregulatory factors; (2) the mechanisms to escape immune surveillance
utilized by several viruses, such as human cytomegalovirus, herpes simplex virus type 1, rabies virus, hepatitis C virus,
influenza virus type A and human immunodeficiency virus 1 (HIV-1); and (3) cytokine/chemokine network and stem cell transplantation,
since they seem to modulate cell migration by the downregulation of chemokine receptor expression and mesenchymal stem cell
activity blocking of effector cell functions and the generation of regulatory T cells. However, the immunomodulatory circuits
mediated by HLA-G proteins still remain to be clarified. 相似文献
158.
Intracellular deposits of aggregated alpha-synuclein are a hallmark of Parkinson’s disease. Protein–protein interactions are
critical in the regulation of cell proteostasis. Synphilin-1 interacts both in vitro and in vivo with alpha-synuclein promoting
its aggregation. We report here that synphilin-1 specifically inhibits the degradation of alpha-synuclein wild-type and its
missense mutants by the 20S proteasome due at least in part by the interaction of the ankyrin and coiled-coil domains of synphilin-1
(amino acids 331–555) with the N-terminal region (amino acids 1–60) of alpha-synuclein. Co-expression of synphilin-1 and alpha-synuclein
wild-type in HeLa and N2A cells produces a specific increase in the half-life of alpha-synuclein, as degradation of unstable
fluorescent reporters is not affected. Synphilin-1 inhibition can be relieved by co-expression of Siah-1 that targets synphilin-1
to degradation. Synphilin-1 inhibition of the proteasomal pathway of degradation of alpha-synuclein may help to understand
the pathophysiological changes occurring in PD and other synucleinopathies. 相似文献
159.
Gudbjartsson DF Sulem P Stacey SN Goldstein AM Rafnar T Sigurgeirsson B Benediktsdottir KR Thorisdottir K Ragnarsson R Sveinsdottir SG Magnusson V Lindblom A Kostulas K Botella-Estrada R Soriano V Juberías P Grasa M Saez B Andres R Scherer D Rudnai P Gurzau E Koppova K Kiemeney LA Jakobsdottir M Steinberg S Helgason A Gretarsdottir S Tucker MA Mayordomo JI Nagore E Kumar R Hansson J Olafsson JH Gulcher J Kong A Thorsteinsdottir U Stefansson K 《Nature genetics》2008,40(7):886-891
Fair color increases risk of cutaneous melanoma (CM) and basal cell carcinoma (BCC). Recent genome-wide association studies have identified variants affecting hair, eye and skin pigmentation in Europeans. Here, we assess the effect of these variants on risk of CM and BCC in European populations comprising 2,121 individuals with CM, 2,163 individuals with BCC and over 40,000 controls. A haplotype near ASIP, known to affect a similar spectrum of pigmentation traits as MC1R variants, conferred significant risk of CM (odds ratio (OR) = 1.45, P = 1.2 x 10(-9)) and BCC (OR = 1.33, P = 1.2 x 10(-6)). The variant in TYR encoding the R402Q amino acid substitution, previously shown to affect eye color and tanning response, conferred risk of CM (OR = 1.21, P = 2.8 x 10(-7)) and BCC (OR = 1.14, P = 6.1 x 10(-4)). An eye color variant in TYRP1 was associated with risk of CM (OR = 1.15, P = 4.6 x 10(-4)). The association of all three variants is robust with respect to adjustment for the effect of pigmentation. 相似文献
160.