全文获取类型
收费全文 | 19255篇 |
免费 | 70篇 |
国内免费 | 88篇 |
专业分类
系统科学 | 119篇 |
丛书文集 | 121篇 |
教育与普及 | 45篇 |
理论与方法论 | 60篇 |
现状及发展 | 8522篇 |
研究方法 | 923篇 |
综合类 | 9362篇 |
自然研究 | 261篇 |
出版年
2013年 | 166篇 |
2012年 | 315篇 |
2011年 | 512篇 |
2010年 | 130篇 |
2008年 | 377篇 |
2007年 | 417篇 |
2006年 | 428篇 |
2005年 | 425篇 |
2004年 | 369篇 |
2003年 | 386篇 |
2002年 | 349篇 |
2001年 | 707篇 |
2000年 | 685篇 |
1999年 | 428篇 |
1994年 | 317篇 |
1992年 | 399篇 |
1991年 | 286篇 |
1990年 | 339篇 |
1989年 | 295篇 |
1988年 | 255篇 |
1987年 | 323篇 |
1986年 | 321篇 |
1985年 | 399篇 |
1984年 | 304篇 |
1983年 | 277篇 |
1982年 | 261篇 |
1981年 | 246篇 |
1980年 | 226篇 |
1979年 | 627篇 |
1978年 | 462篇 |
1977年 | 437篇 |
1976年 | 383篇 |
1975年 | 383篇 |
1974年 | 468篇 |
1973年 | 439篇 |
1972年 | 389篇 |
1971年 | 449篇 |
1970年 | 623篇 |
1969年 | 485篇 |
1968年 | 523篇 |
1967年 | 473篇 |
1966年 | 430篇 |
1965年 | 329篇 |
1959年 | 158篇 |
1958年 | 254篇 |
1957年 | 168篇 |
1956年 | 162篇 |
1955年 | 144篇 |
1954年 | 144篇 |
1948年 | 132篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
401.
402.
403.
Antoni Camins Javier G. Pizarro Daniel Alvira Javier Gutierrez-Cuesta Aurelio Vazquez de la Torre Jaume Folch Francesc X. Sureda Ester Verdaguer Felix Junyent Joaquín Jordán Isidre Ferrer Mercè Pallàs 《Cellular and molecular life sciences : CMLS》2010,67(22):3865-3882
In the present study we demonstrated that neurotoxin MPP+-induced DNA damage is followed by ataxia telangiectasia muted (ATM) activation either in cerebellar granule cells (CGC) or in B65 cell line. In CGC, the selective ATM inhibitor KU-55933 showed neuroprotective effects against MPP+-induced neuronal cell loss and apoptosis, lending support to the key role of ATM in experimental models of Parkinson’s disease. Likewise, we showed that knockdown of ATM levels in neuroblastoma B65 cells using an ATM-specific siRNA attenuates the phosphorylation of retinoblastoma protein without affecting other cell-cycle proteins involved in the G0/G1 cell-cycle phase. Moreover, we demonstrated DNA damage, in human brain samples of PD patients. These findings support a model in which MPP+ leads to ATM activation with a subsequent DNA damage response and activation of pRb. Therefore, this study demonstrates a new link between DNA damage by MPP+ and cell-cycle re-entry through retinoblastoma protein phosphorylation. 相似文献
404.
Nicole Schwarz Jessica Pruessmeyer Franz M. Hess Daniela Dreymueller Elena Pantaler Anne Koelsch Reinhard Windoffer Matthias Voss Alisina Sarabi Christian Weber Antonio S. Sechi Stefan Uhlig Andreas Ludwig 《Cellular and molecular life sciences : CMLS》2010,67(24):4233-4248
The surface-expressed transmembrane CX3C chemokine ligand 1 (CX3CL1/fractalkine) induces firm adhesion of leukocytes expressing its receptor CX3CR1. After shedding by the disintegrins and metalloproteinases (ADAM) 10 and 17, CX3CL1 also acts as soluble leukocyte chemoattractant. Here, we demonstrate that transmembrane CX3CL1 expressed on both endothelial and epithelial cells induces leukocyte transmigration. To investigate the underlying mechanism, we generated CX3CR1 variants lacking the intracellular aspartate-arginine-tyrosine (DRY) motif or the intracellular C-terminus which led to a defect in intracellular calcium response and impaired ligand uptake, respectively. While both variants effectively mediated firm cell adhesion, they failed to induce transmigration and rather mediated retention of leukocytes on the CX3CL1-expressing cell layer. Targeting of ADAM10 led to increased adhesion but reduced transmigration in response to transmembrane CX3CL1, while transmigration towards soluble CX3CL1 was not affected. Thus, transmembrane CX3CL1 mediates leukocyte transmigration via the DRY motif and C-terminus of CX3CR1 and the activity of ADAM10. 相似文献
405.
Large intergenic non-coding RNA-RoR modulates reprogramming of human induced pluripotent stem cells 总被引:1,自引:0,他引:1
406.
Alcázar R García AV Kronholm I de Meaux J Koornneef M Parker JE Reymond M 《Nature genetics》2010,42(12):1135-1139
Accumulation of genetic incompatibilities within species can lead to reproductive isolation and, potentially, speciation. In this study, we show that allelic variation at SRF3 (Strubbelig Receptor Family 3), encoding a receptor-like kinase, conditions the occurrence of incompatibility between Arabidopsis thaliana accessions. The geographical distribution of SRF3 alleles reveals that allelic forms causing epistatic incompatibility with a Landsberg erecta allele at the RPP1 resistance locus are present in A. thaliana accessions in central Asia. Incompatible SRF3 alleles condition for an enhanced early immune response to pathogens as compared to the resistance-dampening effect of compatible SRF3 forms in isogenic backgrounds. Variation in disease susceptibility suggests a basis for the molecular patterns of a recent selective sweep detected at the SRF3 locus in central Asian populations. 相似文献
407.
The developmental dynamics of the maize leaf transcriptome 总被引:5,自引:0,他引:5
408.
Genome-wide association studies of 14 agronomic traits in rice landraces 总被引:20,自引:0,他引:20
Huang X Wei X Sang T Zhao Q Feng Q Zhao Y Li C Zhu C Lu T Zhang Z Li M Fan D Guo Y Wang A Wang L Deng L Li W Lu Y Weng Q Liu K Huang T Zhou T Jing Y Li W Lin Z Buckler ES Qian Q Zhang QF Li J Han B 《Nature genetics》2010,42(11):961-967
Uncovering the genetic basis of agronomic traits in crop landraces that have adapted to various agro-climatic conditions is important to world food security. Here we have identified ~ 3.6 million SNPs by sequencing 517 rice landraces and constructed a high-density haplotype map of the rice genome using a novel data-imputation method. We performed genome-wide association studies (GWAS) for 14 agronomic traits in the population of Oryza sativa indica subspecies. The loci identified through GWAS explained ~ 36% of the phenotypic variance, on average. The peak signals at six loci were tied closely to previously identified genes. This study provides a fundamental resource for rice genetics research and breeding, and demonstrates that an approach integrating second-generation genome sequencing and GWAS can be used as a powerful complementary strategy to classical biparental cross-mapping for dissecting complex traits in rice. 相似文献
409.
410.
José Ramón Bertomeu-Sánchez 《Annals of science》2013,70(4):490-516
This paper analyses the development of three methods for detecting bloodstains during the first half of the nineteenth-century in France. After dealing with the main problems in detecting bloodstains, the paper describes the chemical tests introduced in the mid-1820s. Then the first uses of the microscope in the detection of bloodstains around 1827 are discussed. The most controversial method is then examined, the smell test introduced by Jean-Pierre Barruel in 1829, and the debates which took place in French academies and learned societies during ensuing years are surveyed. Moving to the courtrooms a review is conducted of how the different methods were employed in criminal trials. By reviewing these cases, the main arguments against Barruel's test during the 1830s are explored as well as the changes making possible the return of the microscope to legal medicine around 1840. By reconstructing the history of these three methods, the paper reveals how the senses of smell and vision (colours and microscopic images) were employed in order to produce convincing evidence in both academies and courts. The paper questions two linear master narratives that are organized in terms of progress and decline: the development of forensic science as a result of continued technological progress; and the supposed decline of smell in the history of the senses, particularly in the realm of chemistry and medicine. 相似文献