全文获取类型
收费全文 | 3192篇 |
免费 | 12篇 |
国内免费 | 12篇 |
专业分类
系统科学 | 74篇 |
丛书文集 | 24篇 |
教育与普及 | 6篇 |
理论与方法论 | 5篇 |
现状及发展 | 1562篇 |
研究方法 | 133篇 |
综合类 | 1373篇 |
自然研究 | 39篇 |
出版年
2012年 | 43篇 |
2011年 | 74篇 |
2009年 | 18篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 55篇 |
2005年 | 55篇 |
2004年 | 85篇 |
2003年 | 57篇 |
2002年 | 50篇 |
2001年 | 102篇 |
2000年 | 98篇 |
1999年 | 66篇 |
1993年 | 21篇 |
1992年 | 83篇 |
1991年 | 46篇 |
1990年 | 43篇 |
1989年 | 37篇 |
1988年 | 26篇 |
1987年 | 40篇 |
1986年 | 46篇 |
1985年 | 51篇 |
1984年 | 58篇 |
1983年 | 31篇 |
1982年 | 33篇 |
1981年 | 26篇 |
1980年 | 45篇 |
1979年 | 96篇 |
1978年 | 61篇 |
1977年 | 80篇 |
1976年 | 53篇 |
1975年 | 53篇 |
1974年 | 103篇 |
1973年 | 86篇 |
1972年 | 75篇 |
1971年 | 83篇 |
1970年 | 117篇 |
1969年 | 104篇 |
1968年 | 113篇 |
1967年 | 97篇 |
1966年 | 106篇 |
1965年 | 74篇 |
1964年 | 31篇 |
1959年 | 27篇 |
1958年 | 49篇 |
1957年 | 39篇 |
1956年 | 44篇 |
1955年 | 31篇 |
1954年 | 25篇 |
1948年 | 32篇 |
排序方式: 共有3216条查询结果,搜索用时 31 毫秒
801.
This paper presents short‐ and long‐term composite leading indicators (CLIs) of underlying inflation for seven EU countries, namely Belgium, Germany, France, Italy, the Netherlands, Sweden and the UK. CLI and CPI reference series are calculated in terms of both growth rates and in deviations from its trend. The composite leading indicators are based on leading basic series, such as sources of inflation, series containing information on inflation expectations and prices of intermediate goods and services. Neftci's decision rule approach has been applied to transfer movements in the CLIs into a measure of the probability of a cyclical turning point, which enables the screening out of false turning point predictions. Finally, CLIs have been used to analyse the international coherence of price cycles. The forecast performance of CLIs of inflation over the past raises hope that this forecast instrument can be useful in predicting future price movements. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
802.
803.
一类生态系统的持续生存和全局稳定性 总被引:1,自引:0,他引:1
讨论了一类具有连续时滞和功能性反应的两种群两缀块的一类生态系统的动力学行为。两种群之一能在两缀块中迁移,另一种群限制在一个缀块中,应用微分方程定性和稳定性的方法,证明了系统在一定条件下是持续生存的。进一步,得到了系统为全局稳定的充分条件 相似文献
804.
805.
A novel coenzyme from bacterial primary alcohol dehydrogenases. 总被引:11,自引:0,他引:11
806.
DNA double helical fragment at atomic resolution 总被引:18,自引:0,他引:18
M A Viswamitra O Kennard P G Jones G M Sheldrick S Salisbury L Favello Z Shakked 《Nature》1978,273(5664):687-688
807.
抗汉坦病毒单链抗体双元载体的构建 总被引:1,自引:0,他引:1
利用PCR方法,从含有1A8 scFv基因的重组质粒中扩增出抗体基因,并使基因两端携带合适的限制性酶切位点。经多步连接将其克隆入植物表达载体pBI121或pCAMBIA1305.2。酶切结果证明1A8 scFv基因被成功克隆入植物表达载体pBI121及pCAMBIA1305.2,构建获得1A8 scFv-p BI121及1A8 scFv pCAMBI A1305.2重组质粒,并将其转入农杆菌GV3101。抗汉坦病毒mAb 1A 8scFv植物双元表达载体的获得,为进一步在植物中表达该抗体片段奠定了基础。 相似文献
808.
Sara Canato João D. Santos Ana S. Carvalho Kerman Aloria Margarida D. Amaral Rune Matthiesen André O. Falcao Carlos M. Farinha 《Cellular and molecular life sciences : CMLS》2018,75(24):4495-4509
Misfolded F508del-CFTR, the main molecular cause of the recessive disorder cystic fibrosis, is recognized by the endoplasmic reticulum (ER) quality control (ERQC) resulting in its retention and early degradation. The ERQC mechanisms rely mainly on molecular chaperones and on sorting motifs, whose presence and exposure determine CFTR retention or exit through the secretory pathway. Arginine-framed tripeptides (AFTs) are ER retention motifs shown to modulate CFTR retention. However, the interactions and regulatory pathways involved in this process are still largely unknown. Here, we used proteomic interaction profiling and global bioinformatic analysis to identify factors that interact differentially with F508del-CFTR and F508del-CFTR without AFTs (F508del-4RK-CFTR) as putative regulators of this specific ERQC checkpoint. Using LC–MS/MS, we identified kinesin family member C1 (KIFC1) as a stronger interactor with F508del-CFTR versus F508del-4RK-CFTR. We further validated this interaction showing that decreasing KIFC1 levels or activity stabilizes the immature form of F508del-CFTR by reducing its degradation. We conclude that the current approach is able to identify novel putative therapeutic targets that can be ultimately used to the benefit of CF patients. 相似文献
809.
Speliotes EK Willer CJ Berndt SI Monda KL Thorleifsson G Jackson AU Lango Allen H Lindgren CM Luan J Mägi R Randall JC Vedantam S Winkler TW Qi L Workalemahu T Heid IM Steinthorsdottir V Stringham HM Weedon MN Wheeler E Wood AR Ferreira T Weyant RJ Segrè AV Estrada K Liang L Nemesh J Park JH Gustafsson S Kilpeläinen TO Yang J Bouatia-Naji N Esko T Feitosa MF Kutalik Z Mangino M Raychaudhuri S Scherag A Smith AV Welch R Zhao JH Aben KK Absher DM Amin N Dixon AL Fisher E Glazer NL Goddard ME 《Nature genetics》2010,42(11):937-948
Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ~ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10??), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation. 相似文献
810.
Laitinen OH Hytönen VP Nordlund HR Kulomaa MS 《Cellular and molecular life sciences : CMLS》2006,63(24):2992-3017
Chicken avidin and bacterial streptavidin, (strept)avidin, are proteins widely utilized in a number of applications in life
science, ranging from purification and labeling techniques to diagnostics, and from targeted drug delivery to nanotechnology.
(Strept)avidin-biotin technology relies on the extremely tight and specific affinity between (strept)avidin and biotin (dissociation
constant, Kd≈10−14–10−16 M). (Strept)avidins are also exceptionally stable proteins. To study their ligand binding and stability characteristics,
the two proteins have been extensively modified both chemically and genetically. There are excellent accounts of this technology
and chemically modified (strept)avidins, but no comprehensive reviews exist concerning genetically engineered (strept)avidins.
To fill this gap, we here go through the genetically engineered (strept)avidins, summarizing how these constructs were designed
and how they have improved our understanding of the structural and functional characteristics of these proteins, and the benefits
they have provided for (strept)avidin-biotin technology.
Received 22 June 2006; received after revision 1 August 2006; accepted 21 September 2006 相似文献