全文获取类型
收费全文 | 3797篇 |
免费 | 206篇 |
国内免费 | 17篇 |
专业分类
化学 | 2711篇 |
晶体学 | 30篇 |
力学 | 97篇 |
综合类 | 1篇 |
数学 | 492篇 |
物理学 | 447篇 |
无线电 | 242篇 |
出版年
2023年 | 48篇 |
2022年 | 38篇 |
2021年 | 70篇 |
2020年 | 92篇 |
2019年 | 82篇 |
2018年 | 47篇 |
2017年 | 44篇 |
2016年 | 143篇 |
2015年 | 140篇 |
2014年 | 156篇 |
2013年 | 193篇 |
2012年 | 247篇 |
2011年 | 289篇 |
2010年 | 183篇 |
2009年 | 142篇 |
2008年 | 229篇 |
2007年 | 226篇 |
2006年 | 220篇 |
2005年 | 198篇 |
2004年 | 166篇 |
2003年 | 128篇 |
2002年 | 141篇 |
2001年 | 80篇 |
2000年 | 74篇 |
1999年 | 71篇 |
1998年 | 47篇 |
1997年 | 33篇 |
1996年 | 33篇 |
1995年 | 43篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 24篇 |
1991年 | 39篇 |
1990年 | 33篇 |
1989年 | 27篇 |
1987年 | 17篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 23篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1973年 | 6篇 |
1972年 | 10篇 |
排序方式: 共有4020条查询结果,搜索用时 15 毫秒
91.
92.
Stem cell research is one of the most promising fields of modern biomedical research and regenerative medicine. Limited availability and ethical concerns suggest the renouncement of embryonic stem cells (ESCs), thus raising the need for more efficient procedures for the generation of stem cells, ideally through reprogramming of mammalian cells. The small molecule N-benzyl-2-(pyrimidin-4′-ylamino)-thiazole-4-carboxamide (thiazovivin) is known to improve the generation of human induced pluripotent stem cells (iPSCs) from human fibroblasts. We herein describe a highly efficient procedure for the synthesis of thiazovivin over just five steps, which should be suitable for a large-scale application, and the first x-ray crystal structure of the target compound. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] 相似文献
93.
94.
Alexander J. Nichols Emmanuel Roussakis Oliver J. Klein Conor L. Evans 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(14):3745-3748
Hypoxia is an important contributing factor to the development of drug‐resistant cancer, yet few nonperturbative tools exist for studying oxygenation in tissues. While progress has been made in the development of chemical probes for optical oxygen mapping, penetration of such molecules into poorly perfused or avascular tumor regions remains problematic. A click‐assembled oxygen‐sensing (CAOS) nanoconjugate is reported and its properties demonstrated in an in vitro 3D spheroid cancer model. The synthesis relies on the sequential click‐based ligation of poly(amidoamine)‐like subunits for rapid assembly. Near‐infrared confocal phosphorescence microscopy was used to demonstrate the ability of the CAOS nanoconjugates to penetrate hundreds of micrometers into spheroids within hours and to show their sensitivity to oxygen changes throughout the nodule. This proof‐of‐concept study demonstrates a modular approach that is readily extensible to a wide variety of oxygen and cellular sensors for depth‐resolved imaging in tissue and tissue models. 相似文献
95.
96.
97.
98.
Dr. Alexander Hoffmann Cooper Citek Dr. Stephan Binder Arne Goos Prof. Dr. Michael Rübhausen Oliver Troeppner Prof. Dr. Ivana Ivanović‐Burmazović Prof. Dr. Erik C. Wasinger Prof. Dr. T. Daniel P. Stack Prof. Dr. Sonja Herres‐Pawlis 《Angewandte Chemie (International ed. in English)》2013,52(20):5398-5401
99.
Andre Arnebold Oliver Schorsch Johannes Stelten Andreas Hartwig 《Journal of polymer science. Part A, Polymer chemistry》2014,52(12):1693-1699
The industrial applications of benzoxazines are limited due to their high curing temperatures. This drawback can be overcome by more reactive precursor compared to conventional benzoxazines or by application of efficient initiators. We report the synthesis of a new resorcinol‐based benzoxazine and its cationic polymerization with thermolatent super acids, namely organic sulfonium hexafluoroantimonates. This combination of a reactive precursor and an efficient initiator results in a curing temperature below 100 °C (differential scanning calorimetry onset) which is up to now one of the lowest polymerization temperatures for benzoxazine systems. Furthermore, the thermal stability of the formed polybenzoxazine has not been influenced by the applied initiators. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1693–1699 相似文献
100.