全文获取类型
收费全文 | 214379篇 |
免费 | 3796篇 |
国内免费 | 743篇 |
专业分类
化学 | 118173篇 |
晶体学 | 2373篇 |
力学 | 8396篇 |
综合类 | 8篇 |
数学 | 26572篇 |
物理学 | 63396篇 |
出版年
2021年 | 1501篇 |
2020年 | 1776篇 |
2019年 | 1757篇 |
2018年 | 2061篇 |
2017年 | 2022篇 |
2016年 | 4002篇 |
2015年 | 3252篇 |
2014年 | 3835篇 |
2013年 | 10626篇 |
2012年 | 9016篇 |
2011年 | 10529篇 |
2010年 | 6617篇 |
2009年 | 6554篇 |
2008年 | 9583篇 |
2007年 | 9403篇 |
2006年 | 8920篇 |
2005年 | 8494篇 |
2004年 | 7558篇 |
2003年 | 6457篇 |
2002年 | 6174篇 |
2001年 | 6828篇 |
2000年 | 5402篇 |
1999年 | 4071篇 |
1998年 | 3114篇 |
1997年 | 2990篇 |
1996年 | 2848篇 |
1995年 | 2609篇 |
1994年 | 2601篇 |
1993年 | 2399篇 |
1992年 | 2738篇 |
1991年 | 2637篇 |
1990年 | 2409篇 |
1989年 | 2322篇 |
1988年 | 2349篇 |
1987年 | 2244篇 |
1986年 | 2143篇 |
1985年 | 3164篇 |
1984年 | 3134篇 |
1983年 | 2494篇 |
1982年 | 2687篇 |
1981年 | 2597篇 |
1980年 | 2489篇 |
1979年 | 2434篇 |
1978年 | 2506篇 |
1977年 | 2446篇 |
1976年 | 2394篇 |
1975年 | 2342篇 |
1974年 | 2262篇 |
1973年 | 2353篇 |
1972年 | 1328篇 |
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
31.
32.
33.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
34.
35.
36.
37.
Development of biocompatible porous supports is a promising strategy in the field of tissue engineering for the repair and regeneration of bone tissues with severe damage. Graphene oxide aerogels (GOAs) are excellent candidates for the manufacture of these systems due to their porosity, ability to imitate bone structure, and mechanical resistance, and according to their surface chemical reactivity, they can facilitate osseointegration, osteogenesis, osteoinduction and osteoconduction. In this review, synthesis of GOAs from the most primary source is described, and recent studies on the use of these functionalized carbonaceous foams as scaffolding for bone tissue regeneration are presented. 相似文献
38.
ABSTRACTThis study was to investigate the piezotolerance and diversity indices of microflora of Indian white prawn (Fenneropenaeus indicus) after high pressure (HP)-treatment. Indian white prawns subjected to HP-treatments and its effect was studied up to species level and compared with unpressurized samples. The bacterium was identified by using bacterial identification schemes, biochemical tests and API kits (bioMérieux, Marcyl’Etoile, France). Diversity analysis was performed using PRIMER (Plymouth Routines in Multivariate Research) software v 5.2.2. The significant elimination of microflora was found to be proportional with the pressure level. In the case of spore formers, mere destruction was noticed after HP-treatment. Arthrobacter spp., Listeria grayi and Corynebacterium spp. were the most piezotolerant bacteria in HP-treated samples. Diversity indices revealed a significant reduction of microflora of Indian white prawn. The apparent reduction of microflora with pressure level was clearly evident from the diversity indices; moreover a diminished piezotolerance of Gram negative spoilage bacteria was also observed. 相似文献
39.
Functional Carbazole Liquid‐Crystal Block Codendrimers with Optical and Electronic Properties 下载免费PDF全文
Ismael Gracia Beatriz Feringán Prof. José Luis Serrano Dr. Roberto Termine Dr. Attilio Golemme Dr. Ana Omenat Prof. Joaquín Barberá 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1359-1369
The synthesis and characterisation of a family of block codendrimers consisting of highly versatile mesogenic and carbazole‐containing 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) dendrons are reported. The liquid‐crystal behaviour was investigated by means of differential scanning calorimetry, polarised‐light optical microscopy and X‐ray diffraction. Depending on the chemical structure of the constituent dendrons, the codendrimers show lamellar or columnar mesophases. On the basis of the experimental results, models both at the molecular level and in the mesophase are proposed. The physical properties of the block codendrimers derived from the presence of the carbazole moiety in their structure were investigated: photoluminescence in solution and in the mesophase, electrochemical behaviour and hole transport. Electrodeposition of carbazole dendrons afforded a globular supramolecular conformation in which the mesogenic molecular side plays a key role. 相似文献
40.