全文获取类型
收费全文 | 9667篇 |
免费 | 1340篇 |
国内免费 | 1137篇 |
专业分类
化学 | 7221篇 |
晶体学 | 106篇 |
力学 | 479篇 |
综合类 | 110篇 |
数学 | 1201篇 |
物理学 | 3027篇 |
出版年
2024年 | 29篇 |
2023年 | 176篇 |
2022年 | 295篇 |
2021年 | 320篇 |
2020年 | 360篇 |
2019年 | 343篇 |
2018年 | 274篇 |
2017年 | 284篇 |
2016年 | 459篇 |
2015年 | 424篇 |
2014年 | 572篇 |
2013年 | 732篇 |
2012年 | 873篇 |
2011年 | 874篇 |
2010年 | 613篇 |
2009年 | 549篇 |
2008年 | 623篇 |
2007年 | 526篇 |
2006年 | 470篇 |
2005年 | 390篇 |
2004年 | 368篇 |
2003年 | 326篇 |
2002年 | 359篇 |
2001年 | 281篇 |
2000年 | 184篇 |
1999年 | 226篇 |
1998年 | 152篇 |
1997年 | 110篇 |
1996年 | 130篇 |
1995年 | 97篇 |
1994年 | 101篇 |
1993年 | 91篇 |
1992年 | 77篇 |
1991年 | 77篇 |
1990年 | 48篇 |
1989年 | 52篇 |
1988年 | 32篇 |
1987年 | 33篇 |
1986年 | 34篇 |
1985年 | 33篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1963年 | 7篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 15篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Qi Ji 《Tetrahedron》2006,62(11):2529-2536
Regio- and stereocontrolled synthesis and conformational analysis of a series of benzimidazole nucleosides were achieved. A simple method by 1H NMR 1D NOE experiment was developed for estimation of syn or anti conformation of benzimidazole nucleosides. Substituents at C2 of benzimidazole demonstrated to play a key role both in the unexpected regioselectivity of the glycosidic reaction and in the conformation distributions of the final products. 相似文献
112.
113.
114.
A piezoelectric nucleic acid sensor was constructed ofr detection of tumor necrosis factor gene.Two methods were employed for immobilization of nucleic acid probe on gold electrode of piezoelectric crystal.The results show that polyethyleneimine adbesion and glutaraldehyde cross-linking method has higher sensitivity,stability and selectivity than protein A method.The solid-phase nucleic acid hybridization of oligo unclecotides and tumor necrosis factor target gene sequence were monitorde using this sensor.Tumor necrosis factor gene sequence(580bp) was detected by this nucleic acid sensor for the first time. 相似文献
115.
A new selenite ion selective electrode using 4,6-dibromopiaselenole as active material, PVC as membrane matrix and dibutyl phthalate as plasticizer has been developed. An analytically useful potential change occurs from about 10(-6)-10(-1)M Se(IV), and the slope of the linear portion is -23.6 mV/10-fold change in Se(IV) concentration at a temperature of 21 degrees . The electrode shows fairly good selectivity for selenite ion over other anions and has been used for the successful determination of total selenium in human hair. 相似文献
116.
开展正常人体内元素含量的检测研究具有重要生物学意义,不仅可充实我国正常成年人脏器组织元素含量值的基础医学数据,为研究人体内微量元素与健康的关系提供科学依据、也为辐射防护领域内放射性核素的剂量估算提供重要参数。本文从以下五个方面进行了论述:()体内元素含量检测研究的目的、意义及其概况;(2)元素含量检测的重要性及其历史沿革;(3)元素的检测方法及质量控制;(4)人体内脏器组织元素含量的数值;(5)与国外资料相比较。本文着重介绍了我国100例正常成年人20个脏器组织(包括胃、小肠、大肠、心、肝、脾、肺、肾、… 相似文献
117.
Lee JH Je J Schlautmana MA Carraway ER 《Chemical communications (Cambridge, England)》2003,(2):270-271
The maximum intensity, Imax, and time required to reach the maximum emission, taumax, for 1-aminopyrene monitored in 1,1'-oxalyldi-4-methylimidazole (OD4MI) chemiluminescence (CL) reactions are approximately 61 times higher and 16 times faster than their respective values for bis(2,4,6-trichlorophenyl)oxalate (TCPO) CL reactions in the presence of imidazole (ImH). 相似文献
118.
哺乳动物体内氨基酸及蛋白质的非酶糖化反应(Mailard反应)与糖尿病及其并发症的关系已引起广泛关注[1],β-羧乙基锗倍半氧化物(Ge-132)具有预防糖尿病和调节糖代谢的作用[2],研究Ge-132对Mailard反应的抑制作用对于开发防治糖尿病... 相似文献
119.
Densities have been measured for the electrolyte (NaCl, NaBr and NaI)‐monosaccharide (D ‐mannose and D‐ribose)‐water solutions at 298.15 K. These data have been used to calculate the apparent molar volumes of the saccharides (VΦ,S) and electrolytes (VΦ,E) in the studied solutions. Infinite dilution apparent molar volumes, VΦ,S0 and VΦ,E0, have been evaluated, together with the standard transfer volumes of the saccharides (ΔtVS0) from water to aqueous electrolyte solutions and those of the electrolytes (ΔtVE0) from water to aqueous saccharide solutions. It was shown that both the ΔtVS0 and ΔtVE0 values are positive and increase with increasing molalities of sodium halides and saccharides, respectively. Overall, the ΔtVS0 and ΔtVE0 values have the order of NaCl > NaBr > NaI except for NaI‐ribose and NaI‐ribose. Volumetric interaction parameters for the electrolyte‐monosaccharide pairs in water were obtained and interpreted by the stereochemistry of the monosaccharide molecules and the structural interaction model. 相似文献
120.
Kang EJ Cho EJ Ji MK Lee YE Shin DM Choi SY Chung YK Kim JS Kim HJ Lee SG Lah MS Lee E 《The Journal of organic chemistry》2005,70(16):6321-6329
(+)-SCH 351448 (Na+ salt A) was synthesized employing ring-closing olefin metathesis reaction of an open diene diester intermediate for construction of the 28-membered macrodiolide structure. The open diene diester was prepared from the monomeric hydroxy carboxylic acid and two different olefin fragments. The monomeric hydroxy acid was synthesized via Julia-Julia coupling reaction of intermediates derived from the same olefinic fragments. Oxane units in these fragments were prepared by radical cyclization reactions of beta-alkoxyacrylates. Analogous SCH 351448 salts incorporating other mono- and divalent cations may be prepared. Under acidic conditions, SCH 351448 (Na+ salt A) was the most stable complex, but SCH 351448 (Ca2+ salt) and (Na+ salt B) appear to be physiologically important species. 相似文献