全文获取类型
收费全文 | 5008篇 |
免费 | 94篇 |
国内免费 | 29篇 |
专业分类
化学 | 2636篇 |
晶体学 | 49篇 |
力学 | 169篇 |
数学 | 931篇 |
物理学 | 1346篇 |
出版年
2020年 | 42篇 |
2019年 | 39篇 |
2018年 | 29篇 |
2017年 | 30篇 |
2016年 | 64篇 |
2015年 | 57篇 |
2014年 | 74篇 |
2013年 | 224篇 |
2012年 | 190篇 |
2011年 | 256篇 |
2010年 | 115篇 |
2009年 | 102篇 |
2008年 | 203篇 |
2007年 | 193篇 |
2006年 | 206篇 |
2005年 | 204篇 |
2004年 | 153篇 |
2003年 | 146篇 |
2002年 | 141篇 |
2001年 | 134篇 |
2000年 | 112篇 |
1999年 | 77篇 |
1998年 | 51篇 |
1997年 | 64篇 |
1996年 | 83篇 |
1995年 | 80篇 |
1994年 | 101篇 |
1993年 | 106篇 |
1992年 | 95篇 |
1991年 | 89篇 |
1990年 | 75篇 |
1989年 | 85篇 |
1988年 | 58篇 |
1987年 | 74篇 |
1986年 | 58篇 |
1985年 | 102篇 |
1984年 | 82篇 |
1983年 | 48篇 |
1982年 | 75篇 |
1981年 | 70篇 |
1980年 | 61篇 |
1979年 | 69篇 |
1978年 | 72篇 |
1977年 | 56篇 |
1976年 | 67篇 |
1975年 | 65篇 |
1974年 | 69篇 |
1973年 | 101篇 |
1972年 | 38篇 |
1971年 | 31篇 |
排序方式: 共有5131条查询结果,搜索用时 31 毫秒
111.
N-Heterocyclic carbenes (NHCs) are an important class of reactive organic molecules used as ligands, organocatalysts, and σ-donors in a variety of electroneutral ylide or betaine adducts with main-group compounds. An emerging class of betaine adducts made from the reaction of NHCs with carbodiimides (CDIs) form zwitterionic amidinate-like structures with tunable properties based on the highly modular NHC and CDI scaffolds. The adduct stability is controlled by the substituents on the CDI nitrogens, while the NHC substituents greatly affect the configuration of the adduct in the solid state. This Perspective is intended as a primer to these adducts, touching on their history, synthesis, characterization, and general properties. Despite the infancy of the field, NHC–CDI adducts have been applied as amidinate-type ligands for transition metals and nanoparticles, as junctions in zwitterionic polymers, and to stabilize distonic radical cations. These applications and potential future directions are discussed. N-heterocyclic carbene-carbodiimide betaine adducts are zwitterionic amidinate-like structures with tunable properties that have applications as ligands, junctions in supramolecular polymers, and stabilizers for radical cations. 相似文献
112.
The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1,283 of the 1,440 test samples. Of the 157 test samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 75 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive. 相似文献
113.
114.
Abe K Akagi T Anthony PL Antonov R Arnold RG Averett T Band HR Bauer JM Borel H Bosted PE Breton V Button-Shafer J Chen JP Chupp TE Clendenin J Comptour C Coulter KP Court G Crabb D Daoudi M Day D Dietrich FS Dunne J Dutz H Erbacher R Fellbaum J Feltham A Fonvieille H Frlez E Garvey D Gearhart R Gomez J Grenier P Griffioen KA Hoibraten S Hughes EW Hyde-Wright C Johnson JR Kawall D Klein A Kuhn SE Kuriki M Lindgren R Liu TJ Lombard-Nelsen RM Marroncle J Maruyama T Maruyama XK McCarthy J Meyer W 《Physical review letters》1995,74(3):346-350
115.
McFarland KS Naples D Arroyo CG Auchincloss P de Barbaro P Bazarko AO Bernstein RH Bodek A Bolton T Budd H Conrad J Drucker RB Harris DA Johnson RA Kim JH King BJ Kinnel T Koizumi G Koutsoliotas S Lamm MJ Lefmann WC Marsh W McNulty C Mishra SR Nienaber P Nussbaum M Oreglia MJ Perera L Quintas PZ Romosan A Sakumoto WK Schumm BA Sciulli FJ Seligman WG Shaevitz MH Smith WH Spentzouris P Steiner R Stern EG Vakili M Yang UK 《Physical review letters》1995,75(22):3993-3996
116.
117.
118.
119.
120.
Barish B Chadha M Chan S Cowen DF Eigen G Miller JS O'Grady C Urheim J Weinstein AJ Acosta D Athanas M Masek G Paar HP Gronberg J Kutschke R Menary S Morrison RJ Nakanishi S Nelson HN Nelson TK Qiao C Richman JD Ryd A Tajima H Sperka D Witherell MS Procario M Balest R Cho K Daoudi M Ford WT Johnson DR Lingel K Lohner M Rankin P Smith JG Alexander JP Bebek C Berkelman K Bloom K Browder TE Cassel DG Cho HA Coffman DM Crowcroft DS Drell PS Ehrlich R Gaidarev P Galik RS Garcia-Sciveres M Geiser B 《Physical review D: Particles and fields》1995,51(3):1014-1033