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191.
Maria L. Marcante L. Castelli A. Caputo 《Cellular and molecular life sciences : CMLS》1971,27(4):434-435
Riassunto Cellule portatrici di virus derivate da adenocarcinoma della ghiandola salivare coltivate in vitro sono oncogeniche per l'ospite isogenico per circa sei mesi di coltura. Dopo tale periodo perdono l'oncogenicità e non è più possibile ritrovare particelle virali. Sulla base di questi risultati si conclude che il virus è l'agente causale dell'adenocarcinoma della ghiandola salivare del topo C3H/He. 相似文献
192.
Maria T. Pessacq O. R. Rebolledo J. J. Gagliardino 《Cellular and molecular life sciences : CMLS》1971,27(12):1394-1395
Resumen El contenido diafragmático de proteína, glucógeno y DNA fue estudiado a intervalos de 4 h durante las 24 h. Los animales empleados fueron ratones hembras mantenidos en cuartos con períodos de luzoscuridad de 12 h cada uno. Pudo demostrarse que los tres parámetros presentaron una clara variación circadiana, coincidiendo la aparición de los valores máximos y mínimos para todos ellos durante el período de actividad (oscuridad) y reposo (luz) respectivamente.
The authors carried out this work with the aid of grants from the Consejo Nacional de Investigaciones Científicas y Técnicas and Comisión de Investigaciones Cientificas de la Provincia de Buenos Aires. 相似文献
The authors carried out this work with the aid of grants from the Consejo Nacional de Investigaciones Científicas y Técnicas and Comisión de Investigaciones Cientificas de la Provincia de Buenos Aires. 相似文献
193.
Maria L. Schivo Maria A. Marcialis Ornella Flore S. Dessy A. Garzia B. Loddo 《Cellular and molecular life sciences : CMLS》1976,32(7):911-913
Summary 4, 6 dimethyl-2-amino-3, 4, 5-trimethoxyphenylpyrimidine arrests the mitotic cycle of mammalian cells in metaphase, both in vitro and in vivo. The mitostatic effect is promptly reverted by interruption of drug treatment. 相似文献
194.
Romani L Fallarino F De Luca A Montagnoli C D'Angelo C Zelante T Vacca C Bistoni F Fioretti MC Grohmann U Segal BH Puccetti P 《Nature》2008,451(7175):211-215
Half a century ago, chronic granulomatous disease (CGD) was first described as a disease fatally affecting the ability of children to survive infections. Various milestone discoveries have since been made, from an insufficient ability of patients' leucocytes to kill microbes to the underlying genetic abnormalities. In this inherited disorder, phagocytes lack NADPH oxidase activity and do not generate reactive oxygen species, most notably superoxide anion, causing recurrent bacterial and fungal infections. Patients with CGD also suffer from chronic inflammatory conditions, most prominently granuloma formation in hollow viscera. The precise mechanisms of the increased microbial pathogenicity have been unclear, and more so the reasons for the exaggerated inflammatory response. Here we show that a superoxide-dependent step in tryptophan metabolism along the kynurenine pathway is blocked in CGD mice with lethal pulmonary aspergillosis, leading to unrestrained Vgamma1(+) gammadelta T-cell reactivity, dominant production of interleukin (IL)-17, defective regulatory T-cell activity and acute inflammatory lung injury. Although beneficial effects are induced by IL-17 neutralization or gammadelta T-cell contraction, complete cure and reversal of the hyperinflammatory phenotype are achieved by replacement therapy with a natural kynurenine distal to the blockade in the pathway. Effective therapy, which includes co-administration of recombinant interferon-gamma (IFN-gamma), restores production of downstream immunoactive metabolites and enables the emergence of regulatory Vgamma4(+) gammadelta and Foxp3(+) alphabeta T cells. Therefore, paradoxically, the lack of reactive oxygen species contributes to the hyperinflammatory phenotype associated with NADPH oxidase deficiencies, through a dysfunctional kynurenine pathway of tryptophan catabolism. Yet, this condition can be reverted by reactivating the pathway downstream of the superoxide-dependent step. 相似文献
195.
Kuris AM Hechinger RF Shaw JC Whitney KL Aguirre-Macedo L Boch CA Dobson AP Dunham EJ Fredensborg BL Huspeni TC Lorda J Mababa L Mancini FT Mora AB Pickering M Talhouk NL Torchin ME Lafferty KD 《Nature》2008,454(7203):515-518
Parasites can have strong impacts but are thought to contribute little biomass to ecosystems. We quantified the biomass of free-living and parasitic species in three estuaries on the Pacific coast of California and Baja California. Here we show that parasites have substantial biomass in these ecosystems. We found that parasite biomass exceeded that of top predators. The biomass of trematodes was particularly high, being comparable to that of the abundant birds, fishes, burrowing shrimps and polychaetes. Trophically transmitted parasites and parasitic castrators subsumed more biomass than did other parasitic functional groups. The extended phenotype biomass controlled by parasitic castrators sometimes exceeded that of their uninfected hosts. The annual production of free-swimming trematode transmission stages was greater than the combined biomass of all quantified parasites and was also greater than bird biomass. This biomass and productivity of parasites implies a profound role for infectious processes in these estuaries. 相似文献
196.
Formation of catalytically active RNA structures within the spliceosome requires the assistance of proteins. However, little is known about the number and nature of proteins needed to establish and maintain the spliceosome's active site. Here we affinity-purified human spliceosomal C complexes and show that they catalyse exon ligation in the absence of added factors. Comparisons of the composition of the precatalytic versus the catalytic spliceosome revealed a marked exchange of proteins during the transition from the B to the C complex, with apparent stabilization of Prp19-CDC5 complex proteins and destabilization of SF3a/b proteins. Disruption of purified C complexes led to the isolation of a salt-stable ribonucleoprotein (RNP) core that contained both splicing intermediates and U2, U5 and U6 small nuclear RNA plus predominantly U5 and human Prp19-CDC5 proteins and Prp19-related factors. Our data provide insights into the spliceosome's catalytic RNP domain and indicate a central role for the aforementioned proteins in sustaining its catalytically active structure. 相似文献
197.
Thorgeirsson TE Geller F Sulem P Rafnar T Wiste A Magnusson KP Manolescu A Thorleifsson G Stefansson H Ingason A Stacey SN Bergthorsson JT Thorlacius S Gudmundsson J Jonsson T Jakobsdottir M Saemundsdottir J Olafsdottir O Gudmundsson LJ Bjornsdottir G Kristjansson K Skuladottir H Isaksson HJ Gudbjartsson T Jones GT Mueller T Gottsäter A Flex A Aben KK de Vegt F Mulders PF Isla D Vidal MJ Asin L Saez B Murillo L Blondal T Kolbeinsson H Stefansson JG Hansdottir I Runarsdottir V Pola R Lindblad B 《Nature》2008,452(7187):638-642
Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene-environment interaction, highlighting the role of nicotine addiction in the pathology of other serious diseases. 相似文献
198.
Speciation through sensory drive in cichlid fish 总被引:1,自引:0,他引:1
Seehausen O Terai Y Magalhaes IS Carleton KL Mrosso HD Miyagi R van der Sluijs I Schneider MV Maan ME Tachida H Imai H Okada N 《Nature》2008,455(7213):620-626
Theoretically, divergent selection on sensory systems can cause speciation through sensory drive. However, empirical evidence is rare and incomplete. Here we demonstrate sensory drive speciation within island populations of cichlid fish. We identify the ecological and molecular basis of divergent evolution in the cichlid visual system, demonstrate associated divergence in male colouration and female preferences, and show subsequent differentiation at neutral loci, indicating reproductive isolation. Evidence is replicated in several pairs of sympatric populations and species. Variation in the slope of the environmental gradients explains variation in the progress towards speciation: speciation occurs on all but the steepest gradients. This is the most complete demonstration so far of speciation through sensory drive without geographical isolation. Our results also provide a mechanistic explanation for the collapse of cichlid fish species diversity during the anthropogenic eutrophication of Lake Victoria. 相似文献
199.
IgH class switching and translocations use a robust non-classical end-joining pathway 总被引:1,自引:0,他引:1
Yan CT Boboila C Souza EK Franco S Hickernell TR Murphy M Gumaste S Geyer M Zarrin AA Manis JP Rajewsky K Alt FW 《Nature》2007,449(7161):478-482
Immunoglobulin variable region exons are assembled in developing B cells by V(D)J recombination. Once mature, these cells undergo class-switch recombination (CSR) when activated by antigen. CSR changes the heavy chain constant region exons (Ch) expressed with a given variable region exon from Cmu to a downstream Ch (for example, Cgamma, Cepsilon or Calpha), thereby switching expression from IgM to IgG, IgE or IgA. Both V(D)J recombination and CSR involve the introduction of DNA double-strand breaks and their repair by means of end joining. For CSR, double-strand breaks are introduced into switch regions that flank Cmu and a downstream Ch, followed by fusion of the broken switch regions. In mammalian cells, the 'classical' non-homologous end joining (C-NHEJ) pathway repairs both general DNA double-strand breaks and programmed double-strand breaks generated by V(D)J recombination. C-NHEJ, as observed during V(D)J recombination, joins ends that lack homology to form 'direct' joins, and also joins ends with several base-pair homologies to form microhomology joins. CSR joins also display direct and microhomology joins, and CSR has been suggested to use C-NHEJ. Xrcc4 and DNA ligase IV (Lig4), which cooperatively catalyse the ligation step of C-NHEJ, are the most specific C-NHEJ factors; they are absolutely required for V(D)J recombination and have no known functions other than C-NHEJ. Here we assess whether C-NHEJ is also critical for CSR by assaying CSR in Xrcc4- or Lig4-deficient mouse B cells. C-NHEJ indeed catalyses CSR joins, because C-NHEJ-deficient B cells had decreased CSR and substantial levels of IgH locus (immunoglobulin heavy chain, encoded by Igh) chromosomal breaks. However, an alternative end-joining pathway, which is markedly biased towards microhomology joins, supports CSR at unexpectedly robust levels in C-NHEJ-deficient B cells. In the absence of C-NHEJ, this alternative end-joining pathway also frequently joins Igh locus breaks to other chromosomes to generate translocations. 相似文献
200.
Ricci-Vitiani L Lombardi DG Pilozzi E Biffoni M Todaro M Peschle C De Maria R 《Nature》2007,445(7123):111-115
Colon carcinoma is the second most common cause of death from cancer. The isolation and characterization of tumorigenic colon cancer cells may help to devise novel diagnostic and therapeutic procedures. Although there is increasing evidence that a rare population of undifferentiated cells is responsible for tumour formation and maintenance, this has not been explored for colorectal cancer. Here, we show that tumorigenic cells in colon cancer are included in the high-density CD133+ population, which accounts for about 2.5% of the tumour cells. Subcutaneous injection of colon cancer CD133+ cells readily reproduced the original tumour in immunodeficient mice, whereas CD133- cells did not form tumours. Such tumours were serially transplanted for several generations, in each of which we observed progressively faster tumour growth without significant phenotypic alterations. Unlike CD133- cells, CD133+ colon cancer cells grew exponentially for more than one year in vitro as undifferentiated tumour spheres in serum-free medium, maintaining the ability to engraft and reproduce the same morphological and antigenic pattern of the original tumour. We conclude that colorectal cancer is created and propagated by a small number of undifferentiated tumorigenic CD133+ cells, which should therefore be the target of future therapies. 相似文献