全文获取类型
收费全文 | 38666篇 |
免费 | 1556篇 |
国内免费 | 498篇 |
专业分类
化学 | 26614篇 |
晶体学 | 296篇 |
力学 | 1032篇 |
综合类 | 28篇 |
数学 | 6306篇 |
物理学 | 6444篇 |
出版年
2023年 | 234篇 |
2021年 | 551篇 |
2020年 | 657篇 |
2019年 | 642篇 |
2018年 | 510篇 |
2017年 | 469篇 |
2016年 | 1041篇 |
2015年 | 917篇 |
2014年 | 1046篇 |
2013年 | 2102篇 |
2012年 | 2309篇 |
2011年 | 2824篇 |
2010年 | 1408篇 |
2009年 | 1274篇 |
2008年 | 2407篇 |
2007年 | 2370篇 |
2006年 | 2339篇 |
2005年 | 2147篇 |
2004年 | 1846篇 |
2003年 | 1590篇 |
2002年 | 1483篇 |
2001年 | 549篇 |
2000年 | 551篇 |
1999年 | 451篇 |
1998年 | 418篇 |
1997年 | 416篇 |
1996年 | 582篇 |
1995年 | 416篇 |
1994年 | 365篇 |
1993年 | 327篇 |
1992年 | 309篇 |
1991年 | 279篇 |
1990年 | 233篇 |
1989年 | 227篇 |
1988年 | 264篇 |
1987年 | 234篇 |
1986年 | 206篇 |
1985年 | 406篇 |
1984年 | 373篇 |
1983年 | 280篇 |
1982年 | 350篇 |
1981年 | 371篇 |
1980年 | 332篇 |
1979年 | 318篇 |
1978年 | 296篇 |
1977年 | 256篇 |
1976年 | 230篇 |
1975年 | 237篇 |
1974年 | 254篇 |
1973年 | 234篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Verdecho María-José Alarcón-Valero Faustino Pérez-Perales David Alfaro-Saiz Juan-José Rodríguez-Rodríguez Raúl 《Central European Journal of Operations Research》2021,29(4):1231-1251
Central European Journal of Operations Research - Sustainability practice within supply chains remains in an early development phase. Enterprises still need tools that support the integration of... 相似文献
3.
Kielas-Jensen Calvin Cichella Venanzio Casbeer David Manyam Satyanarayana Gupta Weintraub Isaac 《Journal of Optimization Theory and Applications》2021,191(2-3):899-916
Journal of Optimization Theory and Applications - A framework for monitoring a target modeled as Dubins car using multiple UAVs is proposed. The UAVs are subject to minimum and maximum speed,... 相似文献
4.
5.
6.
7.
Henry Dring David Kreutzer Christoph Ritter Andreas Hilgeroth 《Molecules (Basel, Switzerland)》2021,26(1)
Despite the development of targeted therapies in cancer, the problem of multidrug resistance (MDR) is still unsolved. Most patients with metastatic cancer die from MDR. Transmembrane efflux pumps as the main cause of MDR have been addressed by developed inhibitors, but early inhibitors of the most prominent and longest known efflux pump P-glycoprotein (P-gp) were disappointing. Those inhibitors have been used without knowledge about the expression of P-gp by the treated tumor. Therefore the use of inhibitors of transmembrane efflux pumps in clinical settings is reconsidered as a promising strategy in the case of the respective efflux pump expression. We discovered novel symmetric inhibitors of the symmetric efflux pump MRP4 encoded by the ABCC4 gene. MRP4 is involved in many kinds of cancer with resistance to anticancer drugs. All compounds showed better activities than the best known MRP4 inhibitor MK571 in an MRP4-overexpressing cell line assay, and the activities could be related to the various substitution patterns of aromatic residues within the symmetric molecular framework. One of the best compounds was demonstrated to overcome the MRP4-mediated resistance in the cell line model to restore the anticancer drug sensitivity as a proof of concept. 相似文献
8.
Yuwei Wang Jia-Jun Yan Shengnan Hu Prof. David James Young Prof. Hong-Xi Li Prof. Zhi-Gang Ren 《化学:亚洲杂志》2021,16(18):2681-2686
A photoluminescent bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(MeOH)2(H2O)](ClO4)4 ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 μmol/L (0.36 ppm, w/w) for NH3 ⋅ H2O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water. 相似文献
9.
10.
miRNA (miR)-155 is a potential biomarker for breast cancers. We aimed at developing a nanosensor for miR-155 detection by integrating hybridization chain reaction (HCR) and silver nanoclusters (AgNCs). HCR serves as an enzyme-free and isothermal amplification method, whereas AgNCs provide a built-in fluorogenic detection probe that could simplify the downstream analysis. The two components were integrated by adding a nucleation sequence of AgNCs to the hairpin of HCR. The working principle was based on the influence of microenvironment towards the hosted AgNCs, whereby unfolding of hairpin upon HCR has manipulated the distance between the hosted AgNCs and cytosine-rich toehold region of hairpin. As such, the dominant emission of AgNCs changed from red to yellow in the absence and presence of miR-155, enabling a ratiometric measurement of miR with high sensitivity. The limit of detection (LOD) of our HCR-AgNCs nanosensor is 1.13 fM in buffered solution. We have also tested the assay in diluted serum samples, with comparable LOD of 1.58 fM obtained. This shows the great promise of our HCR-AgNCs nanosensor for clinical application. 相似文献