全文获取类型
收费全文 | 312926篇 |
免费 | 2713篇 |
国内免费 | 842篇 |
专业分类
化学 | 127151篇 |
晶体学 | 3991篇 |
力学 | 14543篇 |
综合类 | 7篇 |
数学 | 42171篇 |
物理学 | 88243篇 |
无线电 | 40375篇 |
出版年
2021年 | 1115篇 |
2020年 | 1230篇 |
2019年 | 1216篇 |
2018年 | 11421篇 |
2017年 | 12430篇 |
2016年 | 7115篇 |
2015年 | 3011篇 |
2014年 | 2901篇 |
2013年 | 8400篇 |
2012年 | 11414篇 |
2011年 | 22115篇 |
2010年 | 13773篇 |
2009年 | 14157篇 |
2008年 | 19960篇 |
2007年 | 24177篇 |
2006年 | 8850篇 |
2005年 | 15917篇 |
2004年 | 11312篇 |
2003年 | 10316篇 |
2002年 | 7761篇 |
2001年 | 7559篇 |
2000年 | 6088篇 |
1999年 | 4667篇 |
1998年 | 3809篇 |
1997年 | 3710篇 |
1996年 | 3752篇 |
1995年 | 3346篇 |
1994年 | 3245篇 |
1993年 | 3147篇 |
1992年 | 3375篇 |
1991年 | 3338篇 |
1990年 | 2983篇 |
1989年 | 2900篇 |
1988年 | 2795篇 |
1987年 | 2362篇 |
1986年 | 2275篇 |
1985年 | 3189篇 |
1984年 | 3150篇 |
1983年 | 2578篇 |
1982年 | 2744篇 |
1981年 | 2612篇 |
1980年 | 2571篇 |
1979年 | 2476篇 |
1978年 | 2569篇 |
1977年 | 2405篇 |
1976年 | 2388篇 |
1975年 | 2347篇 |
1974年 | 2221篇 |
1973年 | 2373篇 |
1972年 | 1394篇 |
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
71.
Jasmin Kuhn Philipp M. Klein Nader Al Danaf Joel Z. Nordin Sren Reinhard Dominik M. Loy Miriam Hhn Samir El Andaloussi Don C. Lamb Ernst Wagner Yoshitsugu Aoki Taavi Lehto Ulrich Lchelt 《Advanced functional materials》2019,29(48)
Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of pre‐mRNA splicing. Similar to other classes of nucleic acid‐based therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinyl‐tetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strain‐promoted azide‐alkyne cycloaddition conjugation with splice‐switching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest splice‐switching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2K‐mdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant splice‐switching at very low nanomolar concentrations. The presented aminoethylene‐lipopeptides are thus a promising platform for the generation of PMO‐therapeutics with a favorable activity/toxicity profile. 相似文献
72.
J. Conrad J. Cohen-Tanugi L. E. Strigari 《Journal of Experimental and Theoretical Physics》2015,121(6):1104-1135
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments. 相似文献
73.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
74.
Claudia Poloni Marc C. A. Stuart Pieter van der Meulen Wiktor Szymanski Ben L. Feringa 《Chemical science》2015,6(12):7311-7318
The external photocontrol over peptide folding, by the incorporation of molecular photoswitches into their structure, provides a powerful tool to study biological processes. However, it is limited so far to switches that exhibit only a rather limited geometrical change upon photoisomerization and that show thermal instability of the photoisomer. Here we describe the use of an overcrowded alkene photoswitch to control a model β-hairpin peptide. This photoresponsive unit undergoes a large conformational change and has two thermally stable isomers which has major influence on the secondary structure and the aggregation of the peptide, permitting the phototriggered formation of amyloid-like fibrils. 相似文献
75.
76.
77.
78.
π-Extended molecules are key components for the development of materials science. In fact, polyaromatic structures are fundamental for the scientific and technological progress of fields such as organic electronics and bio-applications. Beneficial properties of π-extended structures are absorption in the visible region, often luminescence, high electron mobilities and stability. Common approaches to adjust the properties of polyaromatic structures to functional setups involve changes in shape and size at the molecular level. Recently, incorporating hetero-elements emerged as successful approach. In this regard, organophosphorus conjugated molecules are new materials holding great promise for potential applications. In this review, we comprehensively discuss the design/development of polyaromatic phosphorus materials and their applicability. We establish structure/property/applicability relationships to provide key guidelines for the engineering of newer, future applications. This article thus provides a source of information for the further development of this rapidly evolving field of research. 相似文献
79.
80.