全文获取类型
收费全文 | 102896篇 |
免费 | 4627篇 |
国内免费 | 4398篇 |
专业分类
化学 | 43841篇 |
晶体学 | 1194篇 |
力学 | 7909篇 |
综合类 | 308篇 |
数学 | 34640篇 |
物理学 | 24029篇 |
出版年
2024年 | 61篇 |
2023年 | 477篇 |
2022年 | 698篇 |
2021年 | 911篇 |
2020年 | 1062篇 |
2019年 | 1118篇 |
2018年 | 11164篇 |
2017年 | 11047篇 |
2016年 | 7197篇 |
2015年 | 2105篇 |
2014年 | 1905篇 |
2013年 | 2336篇 |
2012年 | 6144篇 |
2011年 | 12888篇 |
2010年 | 7496篇 |
2009年 | 7760篇 |
2008年 | 8443篇 |
2007年 | 10433篇 |
2006年 | 1894篇 |
2005年 | 2624篇 |
2004年 | 2492篇 |
2003年 | 2728篇 |
2002年 | 1732篇 |
2001年 | 893篇 |
2000年 | 857篇 |
1999年 | 632篇 |
1998年 | 542篇 |
1997年 | 454篇 |
1996年 | 460篇 |
1995年 | 370篇 |
1994年 | 308篇 |
1993年 | 260篇 |
1992年 | 198篇 |
1991年 | 197篇 |
1990年 | 170篇 |
1989年 | 149篇 |
1988年 | 131篇 |
1987年 | 110篇 |
1986年 | 119篇 |
1985年 | 96篇 |
1984年 | 60篇 |
1983年 | 54篇 |
1982年 | 59篇 |
1981年 | 44篇 |
1980年 | 52篇 |
1979年 | 52篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
991.
Yan B Collins N Wheatley J Irving M Leopold K Chan C Shornikov A Fang L Lee A Stock M Zhao J 《Journal of combinatorial chemistry》2004,6(2):255-261
We have developed a high-throughput purification system to purify combinatorial libraries at a 50-100-mg scale with a throughput of 250 samples/instrument/day. We applied an accelerated retention window method to shorten the purification time and targeted one fraction per injection to simplify data tracking, lower QC workload, and simplify the postpurification processing. First, we determined the accurate retention time and peak height for all compounds using an eight-channel parallel LC/UV/MS system, and calculated the specific preparative HPLC conditions for individual compounds. The preparative HPLC conditions include the compound-specific gradient segment for individual compounds with a fixed gradient slope and the compound-specific UV or ELSD threshold for triggering a fraction collection device. A unique solvent composition or solvent strength was programmed for each compound in the preparative HPLC in order to elute all compounds at the same target time. Considering the possible deviation of the predicted retention time, a 1-min window around the target time was set to collect peaks above a threshold based on UV or ELSD detection. Dual column preparative instruments were used to maximize throughput. We have purified more than 500 000 druglike compounds using this system in the past 3 years. We report various components of this high-throughput purification system and some of our purification results. 相似文献
992.
993.
994.
995.
Phase separation in the formation of hollow particles by suspension polymerization for divinylbenzene/toluene droplets dissolving polystyrene 总被引:1,自引:0,他引:1
Phase-separation behavior within polymerizing divinylbenzene/toluene droplet dissolving polystyrenes (PS) was investigated to clarify the formation mechanism of the hollow polymer particles by suspension polymerization. No hollow particles were obtained at a low content of low-molecular-weight PS where phase separation occurred at high conversion. On the other hand, hollow particles were obtained at a high content of high-molecular-weight PS where phase separation occurred at low conversion. The phase separation in an early stage of the polymerization, which was promoted by the presence of PS and cross-links of polydivinylbenzene, was a key factor for the formation of the hollow structure. 相似文献
996.
本文在近红外光区研究了镱(Ⅲ)和镝(Ⅲ)1mol/L HClO_4溶液的四阶导数吸收光谱,认真选择了仪器操作条件,提高了测定镱和镝的选择性。通过校正系数法,使镱的光度法测定成为可能,克服了在可见光区测定镝需要校正干扰的缺点,达到在混合稀土中直接测定镱和镝的目的。 相似文献
997.
Zhou Q Liu X Zhao Y Jia N Liu L Yan M Jiang Z 《Chemical communications (Cambridge, England)》2005,(39):4941-4942
Single crystal tin nano-rod arrays were fabricated by the electrodeposition method when amphiphilic triblock copolymer P123 was used as a soft template at a concentration much lower than that for forming a liquid crystalline phase. 相似文献
998.
999.
1000.
SynthesesandCharacterizationsof(η~5-C_5H_5)MoFeCo(CO)_8(μ_3-S)and(η~5-C_5H_5)_2Mo_2Fe(CO)_7(μ_3-S):X-rayCrystalStructureof(η~5-C_5H_... 相似文献