全文获取类型
收费全文 | 20009篇 |
免费 | 52篇 |
国内免费 | 62篇 |
专业分类
系统科学 | 281篇 |
丛书文集 | 465篇 |
教育与普及 | 41篇 |
理论与方法论 | 55篇 |
现状及发展 | 9311篇 |
研究方法 | 847篇 |
综合类 | 8922篇 |
自然研究 | 201篇 |
出版年
2012年 | 264篇 |
2011年 | 505篇 |
2010年 | 124篇 |
2009年 | 110篇 |
2008年 | 332篇 |
2007年 | 404篇 |
2006年 | 344篇 |
2005年 | 354篇 |
2004年 | 380篇 |
2003年 | 383篇 |
2002年 | 306篇 |
2001年 | 678篇 |
2000年 | 668篇 |
1999年 | 396篇 |
1992年 | 380篇 |
1991年 | 276篇 |
1990年 | 328篇 |
1989年 | 297篇 |
1988年 | 280篇 |
1987年 | 302篇 |
1986年 | 321篇 |
1985年 | 384篇 |
1984年 | 292篇 |
1983年 | 242篇 |
1982年 | 225篇 |
1981年 | 256篇 |
1980年 | 299篇 |
1979年 | 645篇 |
1978年 | 506篇 |
1977年 | 535篇 |
1976年 | 394篇 |
1975年 | 420篇 |
1974年 | 662篇 |
1973年 | 531篇 |
1972年 | 481篇 |
1971年 | 589篇 |
1970年 | 759篇 |
1969年 | 667篇 |
1968年 | 590篇 |
1967年 | 613篇 |
1966年 | 525篇 |
1965年 | 395篇 |
1964年 | 112篇 |
1959年 | 221篇 |
1958年 | 336篇 |
1957年 | 227篇 |
1956年 | 212篇 |
1955年 | 198篇 |
1954年 | 181篇 |
1948年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
251.
252.
Rooryck C Diaz-Font A Osborn DP Chabchoub E Hernandez-Hernandez V Shamseldin H Kenny J Waters A Jenkins D Kaissi AA Leal GF Dallapiccola B Carnevale F Bitner-Glindzicz M Lees M Hennekam R Stanier P Burns AJ Peeters H Alkuraya FS Beales PL 《Nature genetics》2011,43(3):197-203
3MC syndrome has been proposed as a unifying term encompassing the overlapping Carnevale, Mingarelli, Malpuech and Michels syndromes. These rare autosomal recessive disorders exhibit a spectrum of developmental features, including characteristic facial dysmorphism, cleft lip and/or palate, craniosynostosis, learning disability and genital, limb and vesicorenal anomalies. Here we studied 11 families with 3MC syndrome and identified two mutated genes, COLEC11 and MASP1, both of which encode proteins in the lectin complement pathway (collectin kidney 1 (CL-K1) and MASP-1 and MASP-3, respectively). CL-K1 is highly expressed in embryonic murine craniofacial cartilage, heart, bronchi, kidney and vertebral bodies. Zebrafish morphants for either gene develop pigmentary defects and severe craniofacial abnormalities. Finally, we show that CL-K1 serves as a guidance cue for neural crest cell migration. Together, these findings demonstrate a role for complement pathway factors in fundamental developmental processes and in the etiology of 3MC syndrome. 相似文献
253.
Crossan GP van der Weyden L Rosado IV Langevin F Gaillard PH McIntyre RE;Sanger Mouse Genetics Project Gallagher F Kettunen MI Lewis DY Brindle K Arends MJ Adams DJ Patel KJ 《Nature genetics》2011,43(2):147-152
The evolutionarily conserved SLX4 protein, a key regulator of nucleases, is critical for DNA damage response. SLX4 nuclease complexes mediate repair during replication and can also resolve Holliday junctions formed during homologous recombination. Here we describe the phenotype of the Btbd12 knockout mouse, the mouse ortholog of SLX4, which recapitulates many key features of the human genetic illness Fanconi anemia. Btbd12-deficient animals are born at sub-Mendelian ratios, have greatly reduced fertility, are developmentally compromised and are prone to blood cytopenias. Btbd12(-/-) cells prematurely senesce, spontaneously accumulate damaged chromosomes and are particularly sensitive to DNA crosslinking agents. Genetic complementation reveals a crucial requirement for Btbd12 (also known as Slx4) to interact with the structure-specific endonuclease Xpf-Ercc1 to promote crosslink repair. The Btbd12 knockout mouse therefore establishes a disease model for Fanconi anemia and genetically links a regulator of nuclease incision complexes to the Fanconi anemia DNA crosslink repair pathway. 相似文献
254.
Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 are associated with late-onset Alzheimer's disease 总被引:1,自引:0,他引:1
Naj AC Jun G Beecham GW Wang LS Vardarajan BN Buros J Gallins PJ Buxbaum JD Jarvik GP Crane PK Larson EB Bird TD Boeve BF Graff-Radford NR De Jager PL Evans D Schneider JA Carrasquillo MM Ertekin-Taner N Younkin SG Cruchaga C Kauwe JS Nowotny P Kramer P Hardy J Huentelman MJ Myers AJ Barmada MM Demirci FY Baldwin CT Green RC Rogaeva E St George-Hyslop P Arnold SE Barber R Beach T Bigio EH Bowen JD Boxer A Burke JR Cairns NJ Carlson CS Carney RM Carroll SL Chui HC Clark DG Corneveaux J Cotman CW 《Nature genetics》2011,43(5):436-441
The Alzheimer Disease Genetics Consortium (ADGC) performed a genome-wide association study of late-onset Alzheimer disease using a three-stage design consisting of a discovery stage (stage 1) and two replication stages (stages 2 and 3). Both joint analysis and meta-analysis approaches were used. We obtained genome-wide significant results at MS4A4A (rs4938933; stages 1 and 2, meta-analysis P (P(M)) = 1.7 × 10(-9), joint analysis P (P(J)) = 1.7 × 10(-9); stages 1, 2 and 3, P(M) = 8.2 × 10(-12)), CD2AP (rs9349407; stages 1, 2 and 3, P(M) = 8.6 × 10(-9)), EPHA1 (rs11767557; stages 1, 2 and 3, P(M) = 6.0 × 10(-10)) and CD33 (rs3865444; stages 1, 2 and 3, P(M) = 1.6 × 10(-9)). We also replicated previous associations at CR1 (rs6701713; P(M) = 4.6 × 10(-10), P(J) = 5.2 × 10(-11)), CLU (rs1532278; P(M) = 8.3 × 10(-8), P(J) = 1.9 × 10(-8)), BIN1 (rs7561528; P(M) = 4.0 × 10(-14), P(J) = 5.2 × 10(-14)) and PICALM (rs561655; P(M) = 7.0 × 10(-11), P(J) = 1.0 × 10(-10)), but not at EXOC3L2, to late-onset Alzheimer's disease susceptibility. 相似文献
255.
Burdon KP Macgregor S Hewitt AW Sharma S Chidlow G Mills RA Danoy P Casson R Viswanathan AC Liu JZ Landers J Henders AK Wood J Souzeau E Crawford A Leo P Wang JJ Rochtchina E Nyholt DR Martin NG Montgomery GW Mitchell P Brown MA Mackey DA Craig JE 《Nature genetics》2011,43(6):574-578
We report a genome-wide association study for open-angle glaucoma (OAG) blindness using a discovery cohort of 590 individuals with severe visual field loss (cases) and 3,956 controls. We identified associated loci at TMCO1 (rs4656461[G] odds ratio (OR) = 1.68, P = 6.1 × 10(-10)) and CDKN2B-AS1 (rs4977756[A] OR = 1.50, P = 4.7 × 10(-9)). We replicated these associations in an independent cohort of cases with advanced OAG (rs4656461 P = 0.010; rs4977756 P = 0.042) and two additional cohorts of less severe OAG (rs4656461 combined discovery and replication P = 6.00 × 10(-14), OR = 1.51, 95% CI 1.35-1.68; rs4977756 combined P = 1.35 × 10(-14), OR = 1.39, 95% CI 1.28-1.51). We show retinal expression of genes at both loci in human ocular tissues. We also show that CDKN2A and CDKN2B are upregulated in the retina of a rat model of glaucoma. 相似文献
256.
Hu Yi He DehuanBeijing Institute of Remote Sensing Equipment P. O. Box Beijing China 《系统工程与电子技术(英文版)》1991,(1)
A new type of vocoder system based upon formant analysis is presented in this paper. The LMS adaptive algorithm is used for tracking formants of speech signals. The results of computer simulation show that the new vocoder has better synthesized speech quality. 相似文献
257.
The introduction of human insulin to treat diabetics seemed straightforward. What can account for the problems that have followed? 相似文献
258.
世界优秀男子110 m栏运动员成绩变化分析 总被引:2,自引:0,他引:2
采用文献资料调查、数理统计等科研方法, 对1997年世界田径锦标赛男子110 m栏前 7 名运动员的成绩进行相关分析, 揭示当今男子110 m栏全程速度变化的规律和特点, 并对近 4 年来世界优秀男子 110 m栏运动员与我国男子110 m栏运动员的成绩进行对比分析, 希望能对我国男子110 m栏的训练提供一些新的参考和启示. 相似文献
259.
Error is protean, ubiquitous and crucial in scientific process. In this paper it is argued that understanding scientific process
requires what is currently absent: an adaptable, context-sensitive functional role for error in science that naturally harnesses error identification and avoidance to positive, success-driven, science. This
paper develops a new account of scientific process of this sort, error and success driving Self-Directed Anticipative Learning
(SDAL) cycling, using a recent re-analysis of ape-language research as test example. The example shows the limitations of
other accounts of error, in particular Mayo’s (Error and the growth of experimental knowledge, 1996) error-statistical approach,
and SDAL cycling shows how they can be fruitfully contextualised. 相似文献
260.