全文获取类型
收费全文 | 407篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 1篇 |
丛书文集 | 53篇 |
理论与方法论 | 1篇 |
现状及发展 | 69篇 |
研究方法 | 30篇 |
综合类 | 250篇 |
自然研究 | 5篇 |
出版年
2016年 | 2篇 |
2013年 | 2篇 |
2012年 | 17篇 |
2011年 | 13篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 17篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 16篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1983年 | 4篇 |
1981年 | 1篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 7篇 |
1970年 | 11篇 |
1969年 | 10篇 |
1968年 | 3篇 |
1967年 | 13篇 |
1966年 | 8篇 |
1965年 | 5篇 |
1959年 | 16篇 |
1958年 | 31篇 |
1957年 | 22篇 |
1956年 | 11篇 |
1955年 | 15篇 |
1954年 | 23篇 |
1948年 | 7篇 |
1947年 | 3篇 |
排序方式: 共有409条查询结果,搜索用时 15 毫秒
91.
Mutational hotspot in the p53 gene in human hepatocellular carcinomas. 总被引:66,自引:0,他引:66
Human hepatocellular carcinomas (HCC) from patients in Qidong, an area of high incidence in China, in which both hepatitis B virus and aflatoxin B1 are risk factors, were analysed for mutations in p53, a putative tumour-suppressor gene. Eight of the 16 HCC had a point mutation at the third base position of codon 249. The G----T transversion in seven HCC DNA samples and the G----C transversion in the other HCC are consistent with mutations caused by aflatoxin B1 in mutagenesis experiments. No mutations were found in exons 5,6,8 or the remainder of exon 7. These results contrast with p53 mutations previously reported in carcinomas and sarcomas of human lung, colon, oesophagus and breast; these are primarily scattered over four of the five evolutionarily conserved domains, which include codon 249 (refs 4-9). We suggest that the mutant p53 protein may be responsible for a selective clonal expansion of hepatocytes during carcinogenesis. 相似文献
92.
Genetically determined variation of adenylate kinase in man 总被引:46,自引:0,他引:46
93.
肉食禁忌在不同文化中的表现形式各异。印度教的核心教义中有牛崇拜与牛保护的条文,这个世界第二人口大国至今仍把禁止屠宰母牛的条款写入法律,饲养着约两亿头牛。印度人口的增长与自然资源的紧缺是“不杀生”教义的基础,也是印度人不得不放弃吠陀时代的牛肉美味的原因。在现代农业条件下,废除杀牛禁规不会给印度的饮食节制带来大的改进。没有任何一种动物能够像印度瘤牛那样为人的生存提供如此多的贡献。 相似文献
94.
95.
Muzny DM Scherer SE Kaul R Wang J Yu J Sudbrak R Buhay CJ Chen R Cree A Ding Y Dugan-Rocha S Gill R Gunaratne P Harris RA Hawes AC Hernandez J Hodgson AV Hume J Jackson A Khan ZM Kovar-Smith C Lewis LR Lozado RJ Metzker ML Milosavljevic A Miner GR Morgan MB Nazareth LV Scott G Sodergren E Song XZ Steffen D Wei S Wheeler DA Wright MW Worley KC Yuan Y Zhang Z Adams CQ Ansari-Lari MA Ayele M Brown MJ Chen G Chen Z Clendenning J Clerc-Blankenburg KP Chen R Chen Z Davis C Delgado O Dinh HH Dong W 《Nature》2006,440(7088):1194-1198
After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion. 相似文献
96.
Mayer K Schüller C Wambutt R Murphy G Volckaert G Pohl T Düsterhöft A Stiekema W Entian KD Terryn N Harris B Ansorge W Brandt P Grivell L Rieger M Weichselgartner M de Simone V Obermaier B Mache R Müller M Kreis M Delseny M Puigdomenech P Watson M Schmidtheini T Reichert B Portatelle D Perez-Alonso M Boutry M Bancroft I Vos P Hoheisel J Zimmermann W Wedler H Ridley P Langham SA McCullagh B Bilham L Robben J Van der Schueren J Grymonprez B Chuang YJ Vandenbussche F Braeken M Weltjens I Voet M 《Nature》1999,402(6763):769-777
The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins. 相似文献
97.
Li J Jiang T Mao JH Balmain A Peterson L Harris C Rao PH Havlak P Gibbs R Cai WW 《Nature genetics》2004,36(9):952-954
By analyzing genomic copy-number differences using high-resolution mouse whole-genome BAC arrays, we uncover substantial differences in regional DNA content between inbred strains of mice. The identification of these apparently common segmental polymorphisms suggests that these differences can contribute to genetic variability and pathologic susceptibility. 相似文献
98.
99.
U-Pb ages of Kude and Sajia leucogranites in Sajia dome from North Himalaya and their geological implications 总被引:13,自引:0,他引:13
ZHANG Hongfei Nigel Harris Randy Parrish ZHANG Li & ZHAO Zidan .Faculty of Earth Sciences China University of Geosciences Wuhan China .Department of Earth Sciences The Open University Milton Keynes MK AA UK .NERC Isotope Geosciences Laboratory British Geological Survery Nottingham NG GG UK .School of Earth Science Land Resources China University of Geosciences Beijing China 《科学通报(英文版)》2004,49(19):2087-2092
~~U-Pb ages of Kude and Sajia leucogranites in Sajia dome from North Himalaya and their geological implications~~ FallMeetingSuppl.Abstr.,2001,0830h.
10.Lee,J.,Hacker,B.R.,Dinklage,W.S. et al.,Evolution of theKangmarDome, southernTibet:Structural, petrologic, and ther- mochronologic constraints,Tectonics,2000,19:872—895.
11.Parrish,R.R.,Roddick,J.C.,Loveridge,W.D. et al.,Ura- nium-lead analytical techniques at the geochronology laboratory,GeologicalSurvey ofCanada,Geol.Sur… 相似文献
100.
Parkhill J Sebaihia M Preston A Murphy LD Thomson N Harris DE Holden MT Churcher CM Bentley SD Mungall KL Cerdeño-Tárraga AM Temple L James K Harris B Quail MA Achtman M Atkin R Baker S Basham D Bason N Cherevach I Chillingworth T Collins M Cronin A Davis P Doggett J Feltwell T Goble A Hamlin N Hauser H Holroyd S Jagels K Leather S Moule S Norberczak H O'Neil S Ormond D Price C Rabbinowitsch E Rutter S Sanders M Saunders D Seeger K Sharp S Simmonds M Skelton J Squares R Squares S Stevens K 《Nature genetics》2003,35(1):32-40
Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica are closely related Gram-negative beta-proteobacteria that colonize the respiratory tracts of mammals. B. pertussis is a strict human pathogen of recent evolutionary origin and is the primary etiologic agent of whooping cough. B. parapertussis can also cause whooping cough, and B. bronchiseptica causes chronic respiratory infections in a wide range of animals. We sequenced the genomes of B. bronchiseptica RB50 (5,338,400 bp; 5,007 predicted genes), B. parapertussis 12822 (4,773,551 bp; 4,404 genes) and B. pertussis Tohama I (4,086,186 bp; 3,816 genes). Our analysis indicates that B. parapertussis and B. pertussis are independent derivatives of B. bronchiseptica-like ancestors. During the evolution of these two host-restricted species there was large-scale gene loss and inactivation; host adaptation seems to be a consequence of loss, not gain, of function, and differences in virulence may be related to loss of regulatory or control functions. 相似文献