全文获取类型
收费全文 | 4060篇 |
免费 | 262篇 |
国内免费 | 2篇 |
专业分类
4324篇 |
出版年
2023年 | 20篇 |
2022年 | 53篇 |
2021年 | 99篇 |
2020年 | 59篇 |
2019年 | 71篇 |
2018年 | 101篇 |
2017年 | 93篇 |
2016年 | 133篇 |
2015年 | 217篇 |
2014年 | 197篇 |
2013年 | 283篇 |
2012年 | 340篇 |
2011年 | 362篇 |
2010年 | 218篇 |
2009年 | 180篇 |
2008年 | 249篇 |
2007年 | 243篇 |
2006年 | 207篇 |
2005年 | 205篇 |
2004年 | 173篇 |
2003年 | 170篇 |
2002年 | 146篇 |
2001年 | 38篇 |
2000年 | 32篇 |
1999年 | 24篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 23篇 |
1995年 | 25篇 |
1994年 | 19篇 |
1993年 | 30篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 6篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 16篇 |
1966年 | 5篇 |
排序方式: 共有4324条查询结果,搜索用时 15 毫秒
351.
Steffens Travis S. Ramsay Malcolm S. Andriatsitohaina Bertrand Cosby Alexandria E. Lehman Shawn M. Rakotondravony Romule Razafitsalama Mamy Teixeira Helena Radespiel Ute 《International journal of primatology》2022,43(4):636-656
International Journal of Primatology - It is important to understand how sympatric congeners can co-occur within the same landscapes to better understand niche differentiation and how each species... 相似文献
352.
353.
Del-Claro Kleber Anjos Diego V. Torezan-Silingardi Helena Maura 《Journal of Ethology》2022,40(1):31-36
Journal of Ethology - Facilitation is an ecological interaction in which the presence of one species (e.g., ecosystem engineers) alters the environment in a way that enhances growth, survival or... 相似文献
354.
Male poplars have a stronger ability to balance growth and carbohydrate accumulation than do females in response to a short‐term potassium deficiency 下载免费PDF全文
Yanni Yang Hao Jiang Maolin Wang Helena Korpelainen Chunyang Li 《Physiologia plantarum》2015,155(4):400-413
Potassium (K) deficiency influences plant performance, such as ion uptake and carbohydrate transport. However, little is known about differences between males and females in response to K deficiency. In this study, dry matter accumulation, photosynthetic capacity, allocation patterns of K+, Na+ and carbohydrates, and ultrastructural changes in males and females of Populus cathayana exposed to K deficiency were investigated. The results indicated that males maintained a significantly higher K+ content and K+/Na+ ratio in leaves and stems than did females under K deficiency. Moreover, K deficiency significantly increased the sucrose content of females, whereas no significant effect on males was detected. In addition, a comparative analysis showed that males allocated more resources to roots, while females allocated more to leaves, which resulted in sexually different root/shoot (R/S) ratios. Transmission electron microscopic (TEM) observations showed that males suffered fewer injuries than did females. These results suggested that males have a better ability to cope with K deficiency. In addition, the combined effects of salinity and K deficiency on poplars were studied. The results indicated that salt stress aggravates the negative effects caused by K deficiency. Taken together, our study provided evidence for gender‐specific strategies in ion and carbohydrate allocation in poplars exposed to a short‐term K deficiency. In leaves and stems, the lower K+ accumulation inhibited sucrose translocation and resulted in a decreased R/S ratio, which may contribute to males having a stronger ability to balance growth and carbohydrate accumulation when compared with females. 相似文献
355.
Hye Shin Lee Mujeeburahiman Cheerathodi Sankar P. Chaki Steve B. Reyes Yanhua Zheng Zhimin Lu Helena Paidassi Celine DerMardirossian Adam Lacy-Hulbert Gonzalo M. Rivera Joseph H. McCarty 《Molecular and cellular biology》2015,35(8):1401-1413
Directional cell motility is essential for normal development and physiology, although how motile cells spatiotemporally activate signaling events remains largely unknown. Here, we have characterized an adhesion and signaling unit comprised of protein tyrosine phosphatase (PTP)-PEST and the extracellular matrix (ECM) adhesion receptor β8 integrin that plays essential roles in directional cell motility. β8 integrin and PTP-PEST form protein complexes at the leading edge of migrating cells and balance patterns of Rac1 and Cdc42 signaling by controlling the subcellular localization and phosphorylation status of Rho GDP dissociation inhibitor 1 (RhoGDI1). Translocation of Src-phosphorylated RhoGDI1 to the cell''s leading edge promotes local activation of Rac1 and Cdc42, whereas dephosphorylation of RhoGDI1 by integrin-bound PTP-PEST promotes RhoGDI1 release from the membrane and sequestration of inactive Rac1/Cdc42 in the cytoplasm. Collectively, these data reveal a finely tuned regulatory mechanism for controlling signaling events at the leading edge of directionally migrating cells. 相似文献
356.
Evaluation of blood pressure in feline night monkeys (Aotus azarae infulatus) under different restraint protocols 下载免费PDF全文
357.
Jefferson José da Silva Santos Tereza Magalh?es José Valter Joaquim Silva Junior Andréa Nazaré Monteiro Rangel da Silva Marli Tenório Cordeiro Laura Helena Vega Gonzales Gil 《Memórias do Instituto Oswaldo Cruz》2015,110(5):677-683
Full-length dengue virus (DENV) cDNA clones are an invaluable tool for many studies,
including those on the development of attenuated or chimeric vaccines and on
host-virus interactions. Furthermore, the importance of low passage DENV infectious
clones should be highlighted, as these may harbour critical and unique
strain-specific viral components from field-circulating isolates. The successful
construction of a functional Brazilian low passage DENV serotype 2 full-length clone
through homologous recombination reported here supports the use of a strategy that
has been shown to be highly useful by our group for the development of flavivirus
infectious clones and replicons. 相似文献
358.
High osmolarity glycerol response PtcB phosphatase is important for Aspergillus fumigatus virulence 下载免费PDF全文
Lizziane K. Winkelströter Vinícius Leite Pedro Bom Patrícia Alves de Castro Leandra Naira Zambelli Ramalho Maria Helena S. Goldman Neil Andrew Brown Ranjith Rajendran Gordon Ramage Elodie Bovier Thaila Fernanda dos Reis Marcela Savoldi Daisuke Hagiwara Gustavo H. Goldman 《Molecular microbiology》2015,96(1):42-54
Aspergillus fumigatus is a fungal pathogen that is capable of adapting to different host niches and to avoid host defenses. An enhanced understanding of how, and which, A. fumigatus signal transduction pathways are engaged in the regulation of these processes is essential for the development of improved disease control strategies. Protein phosphatases are central to numerous signal transduction pathways. To comprehend the functions of protein phosphatases in A. fumigatus, 32 phosphatase catalytic subunit encoding genes were identified. We have recognized PtcB as one of the phosphatases involved in the high osmolarity glycerol response (HOG) pathway. The ΔptcB mutant has both increased phosphorylation of the p38 MAPK (SakA) and expression of osmo‐dependent genes. The ΔptcB strain was more sensitive to cell wall damaging agents, had increased chitin and β‐1,3‐glucan, and impaired biofilm formation. The ΔptcB strain was avirulent in a murine model of invasive pulmonary aspergillosis. These results stress the importance of the HOG pathway in the regulation of pathogenicity determinants and virulence in A. fumigatus. 相似文献
359.
Emma Tham Anna Lindstrand Avni Santani Helena Malmgren Addie Nesbitt Holly?A. Dubbs Elaine?H. Zackai Michael?J. Parker Francisca Millan Kenneth Rosenbaum Golder?N. Wilson Ann Nordgren 《American journal of human genetics》2015,96(3):507-513
Through a multi-center collaboration study, we here report six individuals from five unrelated families, with mutations in KAT6A/MOZ detected by whole-exome sequencing. All five different de novo heterozygous truncating mutations were located in the C-terminal transactivation domain of KAT6A: : c.3116_3117 delCT, p.(Ser1039∗); c.3830_3831insTT, p.(Arg1278Serfs∗17); c.3879 dupA, p.(Glu1294Argfs∗19); c.4108G>T p.(Glu1370∗) and c.4292 dupT, p.(Leu1431Phefs∗8). An additional subject with a 0.23 MB microdeletion including the entire KAT6A reading frame was identified with genome-wide array comparative genomic hybridization. Finally, by detailed clinical characterization we provide evidence that heterozygous mutations in KAT6A cause a distinct intellectual disability syndrome. The common phenotype includes hypotonia, intellectual disability, early feeding and oromotor difficulties, microcephaly and/or craniosynostosis, and cardiac defects in combination with subtle facial features such as bitemporal narrowing, broad nasal tip, thin upper lip, posteriorly rotated or low-set ears, and microretrognathia. The identification of human subjects complements previous work from mice and zebrafish where knockouts of Kat6a/kat6a lead to developmental defects. NM_001099412.1相似文献
360.
Henni Piirainen Maarit Hellman Helena Tossavainen Perttu Permi Petri Kursula Veli-Pekka Jaakola 《Biophysical journal》2015,108(4):903-917
Understanding how ligands bind to G-protein-coupled receptors and how binding changes receptor structure to affect signaling is critical for developing a complete picture of the signal transduction process. The adenosine A2A receptor (A2AR) is a particularly interesting example, as it has an exceptionally long intracellular carboxyl terminus, which is predicted to be mainly disordered. Experimental data on the structure of the A2AR C-terminus is lacking, because published structures of A2AR do not include the C-terminus. Calmodulin has been reported to bind to the A2AR C-terminus, with a possible binding site on helix 8, next to the membrane. The biological meaning of the interaction as well as its calcium dependence, thermodynamic parameters, and organization of the proteins in the complex are unclear. Here, we characterized the structure of the A2AR C-terminus and the A2AR C-terminus-calmodulin complex using different biophysical methods, including native gel and analytical gel filtration, isothermal titration calorimetry, NMR spectroscopy, and small-angle X-ray scattering. We found that the C-terminus is disordered and flexible, and it binds with high affinity (Kd = 98 nM) to calmodulin without major conformational changes in the domain. Calmodulin binds to helix 8 of the A2AR in a calcium-dependent manner that can displace binding of A2AR to lipid vesicles. We also predicted and classified putative calmodulin-binding sites in a larger group of G-protein-coupled receptors. 相似文献