首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   234704篇
  免费   3504篇
  国内免费   642篇
化学   128583篇
晶体学   2813篇
力学   8991篇
综合类   16篇
数学   25504篇
物理学   72943篇
  2020年   2200篇
  2019年   2286篇
  2018年   2697篇
  2017年   2827篇
  2016年   4511篇
  2015年   2962篇
  2014年   4426篇
  2013年   10841篇
  2012年   8164篇
  2011年   9818篇
  2010年   6894篇
  2009年   6687篇
  2008年   8857篇
  2007年   8620篇
  2006年   8199篇
  2005年   7388篇
  2004年   6703篇
  2003年   6029篇
  2002年   5687篇
  2001年   6819篇
  2000年   5202篇
  1999年   3923篇
  1998年   3122篇
  1997年   2974篇
  1996年   2835篇
  1995年   2757篇
  1994年   2657篇
  1993年   2552篇
  1992年   3199篇
  1991年   2944篇
  1990年   2916篇
  1989年   2899篇
  1988年   2917篇
  1987年   2946篇
  1986年   2743篇
  1985年   3642篇
  1984年   3628篇
  1983年   2851篇
  1982年   2980篇
  1981年   3054篇
  1980年   2819篇
  1979年   3134篇
  1978年   3117篇
  1977年   3258篇
  1976年   3077篇
  1975年   2803篇
  1974年   2749篇
  1973年   2669篇
  1972年   1810篇
  1968年   1867篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
32.
33.
This study was aimed at the development of a conductometric biosensor based on acetylcholinesterase considering the feasibility of its application for the inhibitory analysis of various toxicants. In this paper, the optimum conditions for enzyme immobilization on the transducer surface are selected as well as the optimum concentration of substrate for inhibitory analysis. Sensitivity of the developed biosensor to different classes of toxic compounds (organophosphorus pesticides, heavy metal ions, surfactants, aflatoxin, glycoalkaloids) was tested. It is shown that the developed biosensor can be successfully used for the analysis of pesticides and mycotoxins, as well as for determination of total toxicity of the samples. A new method of biosensor analysis of toxic substances of different classes in complex multicomponent aqueous samples is proposed.  相似文献   
34.
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   
35.
36.
Journal of Sol-Gel Science and Technology - Multifunctional magnetic mesoporous nanocomposites are promising materials to remove the various pollutants from water due to the remarkable properties...  相似文献   
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.
Russian Journal of Organic Chemistry - Herein, we report the sulfonamide-functionalized covalent organic framework (COF-SO3H), prepared by condensation of melamine and terephthalaldehyde and...  相似文献   
39.
40.
ABSTRACT

This 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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号