全文获取类型
收费全文 | 3094篇 |
免费 | 431篇 |
出版年
2023年 | 29篇 |
2022年 | 17篇 |
2021年 | 112篇 |
2020年 | 60篇 |
2019年 | 74篇 |
2018年 | 119篇 |
2017年 | 76篇 |
2016年 | 117篇 |
2015年 | 192篇 |
2014年 | 197篇 |
2013年 | 195篇 |
2012年 | 239篇 |
2011年 | 221篇 |
2010年 | 143篇 |
2009年 | 117篇 |
2008年 | 134篇 |
2007年 | 131篇 |
2006年 | 100篇 |
2005年 | 85篇 |
2004年 | 106篇 |
2003年 | 95篇 |
2002年 | 80篇 |
2001年 | 47篇 |
2000年 | 48篇 |
1999年 | 44篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 30篇 |
1991年 | 34篇 |
1990年 | 40篇 |
1989年 | 36篇 |
1988年 | 34篇 |
1987年 | 35篇 |
1986年 | 25篇 |
1985年 | 29篇 |
1984年 | 29篇 |
1983年 | 29篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1979年 | 24篇 |
1978年 | 18篇 |
1977年 | 20篇 |
1975年 | 19篇 |
1974年 | 20篇 |
1972年 | 15篇 |
1970年 | 16篇 |
排序方式: 共有3525条查询结果,搜索用时 265 毫秒
1.
2.
Guochun Yan Kyle Reeves Dominique Foix Zhujie Li Claudio Cometto Sathiya Mariyappan Mathieu Salanne Jean‐Marie Tarascon 《Liver Transplantation》2019,9(41)
The Na‐ion battery is recognized as a possible alternative to the Li‐ion battery for applications where power and cost override energy density performance. However, the increasing instability of their electrolyte with temperature is still problematic. Thus, a central question remains how to design Na‐based electrolytes. Here, the discovery of a Na‐based electrolyte formulation is reported which enlists four additives (vinylene carbonate, succinonitrile, 1,3‐propane sultone, and sodium difluoro(oxalate)borate) in proper quantities that synergistically combine their positive attributes to enable a stable solid electrolyte interphase at both negative and positive electrodes surface at 55 °C. Moreover, the role of each additive that consists in producing specific NaF coatings, thin elastomers, sulfate‐based deposits, and so on via combined impedance and X‐ray photoelectron spectroscopy is rationalized. It is demonstrated that empirical electrolyte design rules previously established for Li‐ion technology together with theoretical guidance is vital in the quest for better Na‐based electrolytes that can be extended to other chemistries. Overall, this finding, which is implemented to 18 650 cells, widens the route to the rapid development of the Na‐ion technology based on Na3V2(PO4)2F3/C chemistry. 相似文献
3.
Cleavage and blastoderm formation in Coelopa frigida are extremely rapid developmental processes. In short (6–7 minutes) successive cell cycles, nuclei multiply and spread out through the egg. The movement seems to be aided by endoplasmic vesicles and cisternae which are in direct contact with the nuclear membrane. The first cells to separate from the egg plasmodium in early superficial cleavage stages are the pole cells. Precursor material from multivesicular bodies forms the pole cell membranes. The primary nuclei from the posterior pole region are removed from the blastoderm by the pole cell segregation. Blastoderm nuclei from the regions adjacent to the posterior pole migrate into the residual periplasm after pole cell segregation has been completed and constitute the blastoderm nuclei in that region of the egg. Nucleoli are not revealed during internal cleavage. They appear in pole cells shortly after their segregation. The generation time of the blastoderm nuclei increases after the twelfth cleavage. Concurrently, nucleoli form in the blastoderm nuclei and permanent cell membranes separate individual blastoderm cells. After blastoderm cells have been separated from each other, they remain in contact with the interior yolk sac by means of cytoplasmic canals. This contact is maintained at least during the early phases of blastokinesis. Observations on nuclear migration and rapid membrane formation are discussed as examples of protein assembly from subunits as an alternative to de novo protein synthesis in early stages of development. 相似文献
4.
5.
Myotonia congenita (Thomsen's disease) excluded from the region of the myotonic dystrophy locus on chromosome 19 总被引:1,自引:0,他引:1
Manuela Koch Helen Harley M. Sarfarazi K. Bender T. Wienker Barbara Zoll P. S. Harper 《Human genetics》1989,82(2):163-166
Summary Linkage analysis has been carried out in six German families with autosomal dominantly inherited myotonia congenita (Thomsen's disease) using five chromosome 19 markers known to be linked to the gene for myotonic dystrophy (DM). Two of the markers, APOC1 and APOC2, are tightly linked to DM. Close linkage between these markers and myotonia congenita (MC) has been excluded to a distance of 9cM (z=-2.158). These data support the clinical suggestion that MC and DM are non-allelic disorders. 相似文献
6.
7.
8.
9.
10.