全文获取类型
收费全文 | 4165篇 |
免费 | 297篇 |
国内免费 | 1篇 |
出版年
2024年 | 4篇 |
2023年 | 27篇 |
2022年 | 51篇 |
2021年 | 114篇 |
2020年 | 49篇 |
2019年 | 107篇 |
2018年 | 148篇 |
2017年 | 100篇 |
2016年 | 145篇 |
2015年 | 221篇 |
2014年 | 245篇 |
2013年 | 295篇 |
2012年 | 379篇 |
2011年 | 382篇 |
2010年 | 225篇 |
2009年 | 202篇 |
2008年 | 256篇 |
2007年 | 282篇 |
2006年 | 252篇 |
2005年 | 202篇 |
2004年 | 188篇 |
2003年 | 171篇 |
2002年 | 135篇 |
2001年 | 33篇 |
2000年 | 13篇 |
1999年 | 19篇 |
1998年 | 25篇 |
1997年 | 10篇 |
1996年 | 17篇 |
1995年 | 22篇 |
1994年 | 8篇 |
1993年 | 15篇 |
1992年 | 18篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1973年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有4463条查询结果,搜索用时 281 毫秒
51.
Pedro Barbosa Liudmila Zhaunova Simona Debilio Verdiana Steccanella Van Kelly Tony Ly Hiroyuki Ohkura 《The Journal of cell biology》2021,220(2)
Meiosis creates genetic diversity by recombination and segregation of chromosomes. The synaptonemal complex assembles during meiotic prophase I and assists faithful exchanges between homologous chromosomes, but how its assembly/disassembly is regulated remains to be understood. Here, we report how two major posttranslational modifications, phosphorylation and ubiquitination, cooperate to promote synaptonemal complex assembly. We found that the ubiquitin ligase complex SCF is important for assembly and maintenance of the synaptonemal complex in Drosophila female meiosis. This function of SCF is mediated by two substrate-recognizing F-box proteins, Slmb/βTrcp and Fbxo42. SCF-Fbxo42 down-regulates the phosphatase subunit PP2A-B56, which is important for synaptonemal complex assembly and maintenance. 相似文献
52.
53.
54.
Mariana C. Pagotti Ana C. B. B. Candido Maria G. Marçal Tatiana M. Vieira Milton Groppo Márcio L. A. Silva Daniele S. Ferreira Viviane R. Esperandim Antônio E. M. Crotti Lizandra G. Magalhães 《化学与生物多样性》2021,18(12):e2100678
Despite the current treatments against Chagas Disease (CD), this vector-borne parasitic disease remains a serious public health concern. In this study, we have explored the in vitro and/or in vivo trypanocidal and cytotoxic activities of the essential oils (EOs) obtained from Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) (DA-EO), Lippia alba (Mill.) N.E. Brown (Verbenaceae) (LA-EO), and Tetradenia riparia (Hochst.) Codd (Lamiaceae) (TR-EO) grown in Brazil Southeast. DA-EO was the most active against the trypomastigote and amastigote forms in vitro; the IC50 values were 8.7 and 12.2 μg mL−1, respectively. The EOs displayed moderate toxicity against LLCMK2 cells, but the DA-EO showed high selectivity index (SI) for trypomastigote (SI=33.2) and amastigote (SI=11.7) forms. Treatment with 20 mg/kg DA-EO, LA-EO, or TR-EO for 20 days by intraperitoneal administration reduced parasitemia by 6.36 %, 4.74 %, and 32.68 % on day 7 and by 12.04 %, 27.96 %, and 65.5 % on day 9. These results indicated that DA-EO, LA-EO, and TR-EO have promising trypanocidal potential in vitro, whereas TR-EO has also potential trypanocidal effects in vivo. 相似文献
55.
Guarnera Daniele Carrera Erasmo Hansen Christopher J. Maiarù Marianna 《Biomechanics and modeling in mechanobiology》2021,20(5):1969-1980
Biomechanics and Modeling in Mechanobiology - This paper proposes a novel experimental investigation based on 3D printing to validate numerical models for biomechanics simulations. Soft elastomeric... 相似文献
56.
Matthew Oldfield Daniele Dini Gianpaolo Giordano Ferdinando Rodriguez y Baena 《Computer methods in biomechanics and biomedical engineering》2013,16(5):530-543
Detailed finite element modelling of needle insertions into soft tissue phantoms encounters difficulties of large deformations, high friction, contact loading and material failure. This paper demonstrates the use of cohesive elements in high-resolution finite element models to overcome some of the issues associated with these factors. Experiments are presented enabling extraction of the strain energy release rate during crack formation. Using data from these experiments, cohesive elements are calibrated and then implemented in models for validation of the needle insertion process. Successful modelling enables direct comparison of finite element and experimental force–displacement plots and energy distributions. Regions of crack creation, relaxation, cutting and full penetration are identified. By closing the loop between experiments and detailed finite element modelling, a methodology is established which will enable design modifications of a soft tissue probe that steers through complex mechanical interactions with the surrounding material. 相似文献
57.
58.
Maria Eugenia Carlotti Elena Ugazio Simona Sapino Ivana Fenoglio Giovanna Greco Bice Fubini 《Free radical research》2013,47(3):312-322
TiO2 nanoparticles hazard is associated to their photocatalytic activity causing release of DNA damaging ROS (Reactive Oxygen Species), lipid peroxidation and skin damage. Various coatings have been proposed to minimize photocatalysis, while keeping the potential to block UV radiations. Uncoated and variously coated commercial nano-titania have been classified on the basis of UVB-induced lipoperoxidation of linoleic acid. A selection of the most and the least protective specimens was then examined by ESR (Electron Spin Resonance) to evidence the presence of surface paramagnetic centres and the release of ROS in aqueous suspensions (spin trapping). Paramagnetic centres and ROS were correlated with the extent of lipid peroxidation. When tested on porcine skin (mimicking the human one), titania acted as on linoleic acid. The combined use of lipid peroxidation of simple fatty acids with ESR analysis is here proposed as a possible screening tool for the evaluation of the potential toxicity of nano-titania in sunscreen preparations. 相似文献
59.
60.