全文获取类型
收费全文 | 11896篇 |
免费 | 888篇 |
国内免费 | 1628篇 |
专业分类
化学 | 5635篇 |
晶体学 | 62篇 |
力学 | 336篇 |
综合类 | 168篇 |
数学 | 6663篇 |
物理学 | 1548篇 |
出版年
2024年 | 4篇 |
2023年 | 148篇 |
2022年 | 181篇 |
2021年 | 320篇 |
2020年 | 352篇 |
2019年 | 408篇 |
2018年 | 347篇 |
2017年 | 392篇 |
2016年 | 338篇 |
2015年 | 273篇 |
2014年 | 463篇 |
2013年 | 1231篇 |
2012年 | 439篇 |
2011年 | 564篇 |
2010年 | 489篇 |
2009年 | 660篇 |
2008年 | 708篇 |
2007年 | 907篇 |
2006年 | 733篇 |
2005年 | 678篇 |
2004年 | 601篇 |
2003年 | 651篇 |
2002年 | 508篇 |
2001年 | 417篇 |
2000年 | 348篇 |
1999年 | 341篇 |
1998年 | 327篇 |
1997年 | 297篇 |
1996年 | 220篇 |
1995年 | 173篇 |
1994年 | 168篇 |
1993年 | 106篇 |
1992年 | 104篇 |
1991年 | 79篇 |
1990年 | 64篇 |
1989年 | 48篇 |
1988年 | 49篇 |
1987年 | 48篇 |
1986年 | 30篇 |
1985年 | 47篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1982年 | 22篇 |
1981年 | 20篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 4篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 246 毫秒
51.
Megan L. Qualls Dr. Jinchao Lou Dillon P. McBee Prof. Joshua A. Baccile Prof. Michael D. Best 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(45):e202201164
Liposomes are effective therapeutic delivery nanocarriers due to their ability to encapsulate and enhance the pharmacokinetic properties of a wide range of therapeutics. Two primary areas in which improvement is needed for liposomal drug delivery is to enhance the ability to infiltrate cells and to facilitate derivatization of the liposome surface. Herein, we report a liposome platform incorporating a cyclic disulfide lipid (CDL) for the dual purpose of enhancing cell entry and functionalizing the liposome membrane through thiol-disulfide exchange. In order to accomplish this, CDL-1 and CDL-2 , composed of lipoic acid (LA) or asparagusic acid (AA) appended to a lipid scaffold, were designed and synthesized. A fluorescence-based microplate immobilization assay was implemented to show that these compounds enable convenient membrane decoration through reaction with thiol-functionalized small molecules. Additionally, fluorescence microscopy experiments indicated dramatic enhancements in cellular delivery when CDLs were incorporated within liposomes. These results demonstrate that multifunctional CDLs serve as an exciting liposome system for surface decoration and enhanced cellular delivery. 相似文献
52.
《Journal of Pure and Applied Algebra》2022,226(11):107116
It was proved in [4] that every group ring of a torsion abelian group over a commutative local ring is a semi-clean ring. It was asked in [4] whether every group ring of a torsion abelian group over a commutative clean ring is a semi-clean ring and whether every group ring of a torsion abelian group over a commutative semi-clean ring is a semi-clean ring. In this paper, we give a positive answer to question 1 and a negative answer to question 2. 相似文献
53.
Zachary Cline 《Journal of Pure and Applied Algebra》2019,223(8):3635-3664
Let q be an nth root of unity for and let be the Taft (Hopf) algebra of dimension . In 2001, Susan Montgomery and Hans-Jürgen Schneider classified all non-trivial -module algebra structures on an n-dimensional associative algebra A. They further showed that each such module structure extends uniquely to make A a module algebra over the Drinfel'd double of . We explore what it is about the Taft algebras that leads to this uniqueness, by examining actions of (the Drinfel'd double of) Hopf algebras H “close” to the Taft algebras on finite-dimensional algebras analogous to A above. Such Hopf algebras H include the Sweedler (Hopf) algebra of dimension 4, bosonizations of quantum linear spaces, and the Frobenius–Lusztig kernel . 相似文献
54.
Evangelia Gazaki 《Mathematische Nachrichten》2019,292(8):1716-1726
In this short note we extend some results obtained in [7]. First, we prove that for an abelian variety A with good ordinary reduction over a finite extension of with p an odd prime, the Albanese kernel of A is the direct sum of its maximal divisible subgroup and a torsion group. Second, for a semi‐abelian variety G over a perfect field k, we construct a decreasing integral filtration of Suslin's singular homology group, , such that the successive quotients are isomorphic to a certain Somekawa K‐group. 相似文献
55.
56.
Calixarenes are known to form host–guest complexes and supramolecular nanoassemblies with well-defined architectures. However, the use of these materials in conjunction with drug moieties is still under explored. One reason is the insufficient biocompatibility studies. Our present study represents a systematic in vitro investigation of the cytotoxicity associated with C-methylresorcin[4]arene, C-methylpyrogallol[4]arene, p-phosphonated calix[8]arene and a metal-seamed calixarene–copper(II) complex, using human HEK293 and rat C6G cell lines and two different cell viability assays (MTT and CellTiter-Glo) to avoid species-biased results. All compounds showed low to moderate toxicity. The trend in the CC50 values indicated that the suppression of the coordination ability and the presence of phosphonate groups decrease the overall cytotoxicity of the compounds. The results of this study not only establish calixarenes and their immediate families as potential drug carriers and drug modifiers, but also reveal a pathway for fine-tuning their toxicological behaviour by appropriate chemical modification. 相似文献
57.
In this article, we mainly consider the existence problem of a group divisible design GDD of type . We present two recursive constructions for this configuration using candelabra systems and construct explicitly a few small examples admitting given automorphism groups. As an application, several new infinite classes of GDD s of type are produced. Meanwhile a few new infinite families on candelabra quadruple systems with group sizes being odd and stem size greater than one are also obtained. 相似文献
58.
59.
Julian P. Edwards William J. Wolf Robert H. Grubbs 《Journal of polymer science. Part A, Polymer chemistry》2019,57(3):228-242
Cyclic polymers have drawn considerable interest for their peculiar physical properties in comparison to linear polymers, despite their equivalent compositions. Synthetically, cyclic polymers can be accessed through either macrocyclic ring‐closure or by ring‐expansion polymerization, but the main challenge with either method is the production of highly pure cyclic polymer samples. This highlight describes advances in the area of cyclic polymer synthesis, with a particular focus on ring‐expansion metathesis polymerization. Methods for characterizing cyclic polymers and assessing their purity are also discussed in order to emphasize the need for additional robust and reliable methods for synthesizing and studying topologically complex macromolecules. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 228–242 相似文献
60.