全文获取类型
收费全文 | 315845篇 |
免费 | 8589篇 |
国内免费 | 6197篇 |
专业分类
化学 | 127831篇 |
晶体学 | 4123篇 |
力学 | 16669篇 |
综合类 | 332篇 |
数学 | 43284篇 |
物理学 | 95926篇 |
无线电 | 42466篇 |
出版年
2022年 | 2745篇 |
2021年 | 3476篇 |
2020年 | 3537篇 |
2019年 | 3730篇 |
2018年 | 13271篇 |
2017年 | 13851篇 |
2016年 | 9624篇 |
2015年 | 4775篇 |
2014年 | 6081篇 |
2013年 | 9935篇 |
2012年 | 13731篇 |
2011年 | 22908篇 |
2010年 | 15804篇 |
2009年 | 16184篇 |
2008年 | 20284篇 |
2007年 | 23650篇 |
2006年 | 9274篇 |
2005年 | 14584篇 |
2004年 | 10571篇 |
2003年 | 9981篇 |
2002年 | 7939篇 |
2001年 | 7832篇 |
2000年 | 6227篇 |
1999年 | 4695篇 |
1998年 | 3958篇 |
1997年 | 3693篇 |
1996年 | 3504篇 |
1995年 | 3044篇 |
1994年 | 2954篇 |
1993年 | 2849篇 |
1992年 | 3147篇 |
1991年 | 3190篇 |
1990年 | 3017篇 |
1989年 | 2679篇 |
1988年 | 2510篇 |
1987年 | 2378篇 |
1986年 | 2137篇 |
1985年 | 2486篇 |
1984年 | 2474篇 |
1983年 | 1922篇 |
1982年 | 1938篇 |
1981年 | 1797篇 |
1980年 | 1663篇 |
1979年 | 1999篇 |
1978年 | 1991篇 |
1977年 | 1918篇 |
1976年 | 1959篇 |
1975年 | 1714篇 |
1974年 | 1750篇 |
1973年 | 1716篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Kazantsev Yu. N. Kraftmakher G. A. Mal’tsev V. P. 《Journal of Communications Technology and Electronics》2019,64(6):550-554
Journal of Communications Technology and Electronics - Approximate formulas for calculating the coefficient of reflection from an artificial magnetic conductor (AMC) based on a capacitive lattice... 相似文献
33.
Stolpovskaya N. V. Kruzhilin A. A. Zorina A. V. Shikhaliev Kh. S. Ledeneva I. V. Kosheleva E. A. Vandyshev D. Yu. 《Russian Journal of Organic Chemistry》2019,55(9):1322-1328
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by... 相似文献
34.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
35.
36.
E. V. Shadrina O. N. Malinkina T. G. Khonina A. B. Shipovskaya V. I. Fomina E. Yu. Larchenko N. A. Popova I. G. Zyryanova L. P. Larionov 《Russian Chemical Bulletin》2015,64(7):1633-1639
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications. 相似文献
37.
Triazines are widely used in agriculture around the world as selective pre‐ and post‐emergence herbicides for the control of broad leaf and grassy weeds. With high toxicity and persistence, triazines can contaminate the environment and crops, so the development of rapid and sensitive methods for the determination of different triazines is necessary. Capillary electrophoresis comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities. This review focuses on the analysis of triazine herbicides with different modes of capillary electrophoresis, including capillary zone electrophoresis, micellar electrokinetic capillary electrophoresis, capillary electrochromatography and nonaqueous capillary electrophoresis. Determinations of triazines in various matrices such as surface water, groundwater, vegetables, soil and grains are emphasized. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
38.
39.
Yeong‐Tarng Shieh Pei‐Yu Tai Chih‐Chia Cheng 《Journal of polymer science. Part A, Polymer chemistry》2019,57(21):2149-2156
Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156 相似文献
40.
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