全文获取类型
收费全文 | 2499篇 |
免费 | 103篇 |
国内免费 | 7篇 |
专业分类
化学 | 1948篇 |
晶体学 | 7篇 |
力学 | 26篇 |
数学 | 314篇 |
物理学 | 314篇 |
出版年
2023年 | 15篇 |
2022年 | 14篇 |
2021年 | 32篇 |
2020年 | 58篇 |
2019年 | 39篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 74篇 |
2015年 | 67篇 |
2014年 | 80篇 |
2013年 | 127篇 |
2012年 | 161篇 |
2011年 | 167篇 |
2010年 | 91篇 |
2009年 | 81篇 |
2008年 | 145篇 |
2007年 | 118篇 |
2006年 | 120篇 |
2005年 | 123篇 |
2004年 | 134篇 |
2003年 | 91篇 |
2002年 | 101篇 |
2001年 | 49篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 31篇 |
1997年 | 38篇 |
1996年 | 40篇 |
1995年 | 39篇 |
1994年 | 46篇 |
1993年 | 42篇 |
1992年 | 36篇 |
1991年 | 22篇 |
1990年 | 25篇 |
1989年 | 26篇 |
1988年 | 29篇 |
1987年 | 15篇 |
1985年 | 28篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1980年 | 12篇 |
1979年 | 18篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1973年 | 9篇 |
1970年 | 10篇 |
排序方式: 共有2609条查询结果,搜索用时 0 毫秒
121.
Hao Zhang Dr. Benhua Wang Dr. Kai Seehafer Prof. Dr. Uwe H. F. Bunz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(35):7779-7782
A cross-reactive optical sensor array based on poly(p-phenyleneethynylene)s (PPEs) determines Edman degraded amino acids. We report a sensor array composed of three anionic PPEs P1–P3 , and their electrostatic complexes with metal ions (Fe2+, Cu2+, Co2+). We recorded distinct fluorescence intensity response patterns as “fingerprints” of this chemical tongue toward standard phenylthiohydantoin (PTH) amino acids—degradation products of the Edman process. These “fingerprints” were converted into canonical scores by linear discrimination analysis (LDA), which differentiates all of the PTH-amino acids. This array discriminates PTH-amino acid residues degraded from an oligopeptide through Edman sequencing. This approach is complementary to chromatography approaches which rely on mass spectrometry; our array offers the advantage of simplicity. 相似文献
122.
Uwe Schmidt Luis Werner Merle Arrowsmith Andrea Deissenberger Alexander Hermann Alexander Hofmann Stefan Ullrich James D. Mattock Alfredo Vargas Holger Braunschweig 《Angewandte Chemie (International ed. in English)》2020,59(1):325-329
The reaction of aryl‐ and amino(dihydro)boranes with dibora[2]ferrocenophane 1 leads to the formation 1,3‐trans‐dihydrotriboranes by formal hydrogenation and insertion of a borylene unit into the B=B bond. The aryltriborane derivatives undergo reversible photoisomerization to the cis‐1,2‐μ‐H‐3‐hydrotriboranes, while hydride abstraction affords cationic triboranes, which represent the first doubly base‐stabilized B3H4+ analogues. 相似文献
123.
124.
125.
126.
127.
Hans-Joachim Nees Uwe Bergstrßer Heinrich Heydt Manfred Regitz 《Heteroatom Chemistry》1993,4(5):525-530
The (diazoalkyl)phosphanes 4a–e undergo [4 + 1]-cycloaddition reactions with the tetrahalo-orthobenzoquinones 5a,b to furnish the previously unknown (diazoalkyl)phosphoranes 6a–h . The structure of product 6h has been investigated by X-ray crystallography. 相似文献
128.
129.
130.
3,5-Bis(2-hydroxyphenyl)-1H-1,2,4-triazole (H2La) and 4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid (H3Lb) have been prepared, and crystal structure of the intermediate 2-(2-hydroxyphenyl)-4H-1,3-benzoxazin-4-one has been determined. Temperature dependent 1H NMR spectroscopic measurements of H2La indicated dynamic behavior with the equilibrium between the two asymmetric tautomers. For H3Lb, pD-dependent 1H NMR spectroscopic measurements showed small but characteristic shifts in the range of 0 ≤ pD ≤ 1, indicative of a triazole
nitrogen atom protonation; the corresponding pK
a of 0.98 ± 0.04 was determined by spectrophotometric titrations. (H2O, 26°C, 1 M KCl/HCl). Formation of [FeIII(La)]+ (pH 2.5) and [FeIII(La)2]− (pH > 6) was verified by UV-Vis spectroscopy. Complex formation of H3Lb with Al3+ and VO2+ was investigated by 1H NMR spectroscopic titration and cyclic voltammetry, respectively. Single crystals of the phenoxo bridged [VVO(HLb)(EtO)]2·2EtOH were characterized by X-ray structural analysis.
Dedicated to Professor Milan Melník on the occasion of his 70th birthday 相似文献