全文获取类型
收费全文 | 29331篇 |
免费 | 3869篇 |
国内免费 | 2736篇 |
专业分类
化学 | 14723篇 |
晶体学 | 262篇 |
力学 | 1256篇 |
综合类 | 188篇 |
数学 | 2057篇 |
物理学 | 7920篇 |
综合类 | 9530篇 |
出版年
2024年 | 131篇 |
2023年 | 579篇 |
2022年 | 815篇 |
2021年 | 963篇 |
2020年 | 918篇 |
2019年 | 841篇 |
2018年 | 744篇 |
2017年 | 718篇 |
2016年 | 1085篇 |
2015年 | 1164篇 |
2014年 | 1419篇 |
2013年 | 1773篇 |
2012年 | 2167篇 |
2011年 | 2224篇 |
2010年 | 1557篇 |
2009年 | 1437篇 |
2008年 | 1679篇 |
2007年 | 1663篇 |
2006年 | 1476篇 |
2005年 | 1373篇 |
2004年 | 1017篇 |
2003年 | 863篇 |
2002年 | 854篇 |
2001年 | 710篇 |
2000年 | 690篇 |
1999年 | 919篇 |
1998年 | 719篇 |
1997年 | 794篇 |
1996年 | 652篇 |
1995年 | 639篇 |
1994年 | 620篇 |
1993年 | 516篇 |
1992年 | 423篇 |
1991年 | 410篇 |
1990年 | 359篇 |
1989年 | 289篇 |
1988年 | 221篇 |
1987年 | 188篇 |
1986年 | 118篇 |
1985年 | 69篇 |
1984年 | 49篇 |
1983年 | 25篇 |
1982年 | 26篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1975年 | 2篇 |
1957年 | 4篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Yanfeng Chu Huan Yu Yunti Zhang Guangyan Zhang Yingying Ma Renxi Zhuo Xulin Jiang 《Journal of polymer science. Part A, Polymer chemistry》2014,52(23):3346-3355
Biodegradable amphiphilic ABC Y‐shaped triblock copolymer (MPBC) containing PEG, PBLA, and PCL segments was synthesized via the combination of enzymatic ring‐opening polymerization (ROP) of epsilon‐caprolactone, ROP of BLA‐N‐carboxyanhydride and click chemistry, where PEG, PBLA, and PCL are poly(ethylene glycol), poly(benzyl‐l ‐aspartate), and polycaprolactone, respectively. Propynylamine was employed as ROP initiator for the preparation of alkynyl‐terminated PBLA and methyloxy‐PEG with hydroxyl and azide groups at the chain‐end was used as enzymatic ROP initiator for synthesis of monoazido‐midfunctionalized block copolymer mPEG‐b‐PCL. The subsequent click reaction led to the formation of Y‐shaped asymmetric heteroarm terpolymer MPBC. The polymer structures were characterized by different analyses. The MPBC terpolymer self‐assembled into micelles and physically encapsulated drug doxorubicin (DOX) to form DOX‐loaded micelles, which showed good stability and slow drug release. In vitro cytotoxicity study indicated that the MPBC micelles were nontoxic and the DOX‐loaded micelles displayed obvious anticancer activity similar to free DOX against HeLa cells. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3346–3355 相似文献
992.
Lin-Feng You Tao Wei Qian-Wang Zheng Jun-Fang Lin Li-Qiong Guo Bing-Hua Jiang Jia-Jun Huang 《Applied biochemistry and biotechnology》2018,186(4):949-959
Taxoid 10β-O-acetyl transferase (DBAT) is a key enzyme in the biosynthesis of the famous anticancer drug paclitaxel, which catalyses the formation of baccatin III from 10-deacetylbaccatin III (10-DAB). However, the activity essential residues of the enzyme are still unknown, and the acylation mechanism from its natural substrate 10-deacetylbaccatin III and acetyl CoA to baccatin III remains unclear. In this study, the homology modelling, molecular docking, site-directed mutagenesis, and kinetic parameter determination of the enzyme were carried out. The results showed that the enzyme mutant DBATH162A resulted in complete loss of enzymatic activity, suggesting that the residue histidine at 162 was essential to DBAT activity. Residues D166 and R363 which were located in the pocket of the enzyme by homology modelling and molecular docking were also important for DBAT activity through the site-directed mutations. Furthermore, four amino acid residues including S31 and D34 from motif SXXD, D372 and G376 from motif DFGWG also played important roles on acylation. This was the first report of the elucidation of the activity essential residues of DBAT, making it possible for the further structural-based re-design of the enzyme for efficient biotransformation of baccatin III and paclitaxel. 相似文献
993.
994.
995.
996.
997.
998.
Zhong Ju Liu Wenwen Shi Gui Mei Shi Wei Jiang 《International Journal of Theoretical Physics》2018,57(1):184-194
An array of coupled cavities, each of which contains a triangle-down-level atom, is investigated. An effective Hamiltonian can be achieved under the strong classical driving. We can control the transition between Mott-insulator and superfluid states by the classical driving. The frequency conversion in one site has the same effects of nonlinear in BH hamiltonian which can induce insulator-superfluid states. 相似文献
999.
JiGuang Lu Bo Peng Kuo Liu Peng Jiang YouLing Yue Meng Yu Ye-Zhao Yu FeiFei Kou Lin Wang 《中国科学:物理学 力学 天文学(英文版)》2019,(5)
Rotating radio transients(RRATs) are peculiar astronomical objects whose emission mechanism remains under investigation.In this paper, we present observations of three RRATs, J1538+2345, J1854+0306 and J1913+1330, carried out with the Fivehundred-meter Aperture Spherical radio Telescope(FAST). Specifically, we analyze the mean pulse profiles and temporal flux density evolutions of the RRATs. Owing to the high sensitivity of FAST, the derived burst rates of the three RRATs are higher than those in previous reports. RRAT J1854+0306 exhibited a time-dynamic mean pulse profile, whereas RRAT J1913+1330 showed distinct radiation and nulling segments on its pulse intensity trains. The mean pulse profile variation with frequency is also studied for RRAT J1538+2345 and RRAT J1913+1330, and the profiles at different frequencies could be well fitted with a cone-core model and a conal-beam model, respectively. 相似文献
1000.
Jianhao Wang Zhilan Zhu Wenjing Jia Lin Qiu Yufeng Chang Jie Li Luping Ma Ying You Jianpeng Wang Li Liu Jiang Xia Xiaoqian Liu Yong‐Qiang Li Pengju Jiang 《Electrophoresis》2019,40(7):1019-1026
Despite the numerous techniques developed for the studying nanoparticle and peptide interaction nowadays, sensitive and convenient assay in the process of flow, especially to simulate the self‐assembly of quantum dots (QDs) and peptide inflow in blood vessels, still remains big challenges. Here, we report a novel assay for studying the self‐assembly of QDs and peptide, based on CE using a bending capillary. We demonstrate that the semicircles numbers of the bending capillary affect the self‐assembly kinetics of CdSe/ZnS QDs and ATTO‐D3LVPRGSGP9G2H6 peptide. Moreover, benefitting from this novel assay, the effect of the position on the self‐assembly has also been realized. More importantly, we also demonstrate that this novel assay can be used for studying the stability of the QDs–peptide complex inflow. We believe that our novel assay proposed in this work could be further used as a general strategy for the studying nanoparticle–biomolecule interaction or biomolecule–biomolecule interaction. 相似文献