全文获取类型
收费全文 | 868篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 13篇 |
丛书文集 | 1篇 |
教育与普及 | 2篇 |
理论与方法论 | 9篇 |
现状及发展 | 176篇 |
研究方法 | 102篇 |
综合类 | 513篇 |
自然研究 | 58篇 |
出版年
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 51篇 |
2011年 | 110篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 48篇 |
2007年 | 45篇 |
2006年 | 52篇 |
2005年 | 55篇 |
2004年 | 49篇 |
2003年 | 42篇 |
2002年 | 44篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1997年 | 3篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1979年 | 20篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1974年 | 12篇 |
1973年 | 18篇 |
1972年 | 11篇 |
1971年 | 11篇 |
1970年 | 14篇 |
1969年 | 8篇 |
1968年 | 10篇 |
1967年 | 10篇 |
1966年 | 7篇 |
1965年 | 5篇 |
排序方式: 共有874条查询结果,搜索用时 390 毫秒
101.
102.
建立一个有限缓冲区的单服务器模型,证明了在队长有有限二阶矩的条件下,输出过程具强渐近二阶自相似性质与输出过程具强渐近二阶自相似性质等价。 相似文献
103.
Ageing, fitness and neurocognitive function. 总被引:18,自引:0,他引:18
A F Kramer S Hahn N J Cohen M T Banich E McAuley C R Harrison J Chason E Vakil L Bardell R A Boileau A Colcombe 《Nature》1999,400(6743):418-419
104.
R.S.斯特恩 《国外科技新书评介》2006,(12):18-19
高分子概念的形成和高分子科学的出现始于20世纪20年代。当时有些有机化学家开展了缩聚反应及其自由基聚合反应的研究,并通过这些反应相继开发出尼龙(聚酰胺)66、氯丁橡胶、丁苯橡胶和聚甲基丙烯酸甲酯等一大批高分子材料,从而形成了“高分子化学”的研究领域。随着这些合成高分子的出现,解决这些高分子的性能和表征:以及了解其结构对性能的影响等问题也随之变得很必要了。因此从20世纪40年代至50年代,一批化学家、物理学家投入这方面的研究,渐渐形成了“高分子物理”这门新兴的学科。 相似文献
105.
106.
An erosion of the power of people and their communities to control any more than a fragment of their future continues. Educational and governmental policy decisions are, for the most part, mandated from above and/or outside the community. This paper introduces a model which reflects Freire's humanizing pedagogy. This method is a vehicle, an avenue of empowerment for people and their communities to control their own destiny and the future of their community. The model is Interactive Management (IM) and its derivative, The CogniScope System. IM is a specialized system of management using collaborative teamwork to define and resolve highly complex issues. The process includes the integration of the diversity of perceptions of the participants with regard to the given ssues, builds consensus and joint ownership of the process and/or product, and creates a collaborative action plan to accomplish the participants' goals. The principal intangible outcome of the process, however, is the reflective participation, which leads to action, and the learning that occurs among the community of stakeholders present. The process of Interactive Management (IM), enhanced through the use of the CogniScope System, is described and examples of its application by First Nation peoples are shared. 相似文献
107.
108.
109.
Specific inhibition of herpesvirus ribonucleotide reductase by a nonapeptide derived from the carboxy terminus of subunit 2 总被引:15,自引:0,他引:15
Ribonucleotide reductase, an essential enzyme for the synthesis of deoxyribonucleotides, is formed by the association of two nonidentical subunits in almost all prokaryotic and eukaryotic cells. The same model probably holds for the herpes simplex virus (HSV)-encoded ribonucleotide reductase; two polypeptides of relative molecular mass 136,000 (136K; H1) and 40K (H2) (referred to elsewhere as RR1 and RR2; see for example, Dutia et al.) have been associated with the viral enzyme by both genetic and immunological studies. Furthermore, DNA sequence analyses have shown significant stretches of amino-acid homology between these viral polypeptides and those of, respectively, subunit 1 (ref. 12) and subunit 2 (ref. 13) of the Escherichia coli and mammalian enzymes. To assess the involvement of the 40K polypeptide in reductase activity, we synthesized a nonapeptide corresponding to the sequence of its carboxy terminus with the intention of raising neutralizing antibodies specific for the viral activity (E.A.C. et al., in preparation). We report here the unexpected finding that the nonapeptide itself specifically inhibits the HSV ribonucleotide reductase activity in a reversible, non-competitive manner, and we suggest that it does this by impairment of the correct association of the two subunits. This phenomenon emphasizes the potential usefulness of synthetic peptides in probing critical sites involved in macromolecular interactions. 相似文献
110.