全文获取类型
收费全文 | 1915篇 |
免费 | 125篇 |
国内免费 | 2篇 |
专业分类
2042篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 32篇 |
2021年 | 63篇 |
2020年 | 33篇 |
2019年 | 49篇 |
2018年 | 36篇 |
2017年 | 30篇 |
2016年 | 69篇 |
2015年 | 99篇 |
2014年 | 115篇 |
2013年 | 113篇 |
2012年 | 167篇 |
2011年 | 125篇 |
2010年 | 84篇 |
2009年 | 75篇 |
2008年 | 110篇 |
2007年 | 117篇 |
2006年 | 80篇 |
2005年 | 84篇 |
2004年 | 92篇 |
2003年 | 65篇 |
2002年 | 80篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 18篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1974年 | 5篇 |
1972年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有2042条查询结果,搜索用时 0 毫秒
51.
52.
53.
Wounding-Induced Stomatal Closure Requires Jasmonate-Mediated Activation of GORK K+ Channels by a Ca2+ Sensor-Kinase CBL1-CIPK5 Complex 总被引:1,自引:0,他引:1
54.
Polly Campbell Lena Arvalo Heather Martin Charles Chen Shuzhen Sun Ashlee H. Rowe Michael S. Webster Jeremy B. Searle Bret Pasch 《Ecology and evolution》2019,9(22):12886-12896
Behavioral barriers to gene flow often evolve faster than intrinsic incompatibilities and can eliminate the opportunity for hybridization between interfertile species. While acoustic signal divergence is a common driver of premating isolation in birds and insects, its contribution to speciation in mammals is less studied. Here we characterize the incidence of, and potential barriers to, hybridization among three closely related species of grasshopper mice (genus Onychomys). All three species use long‐distance acoustic signals to attract and localize mates; Onychomys arenicola and Onychomys torridus are acoustically similar and morphologically cryptic whereas Onychomys leucogaster is larger and acoustically distinct. We used genotyping‐by‐sequencing (GBS) to test for evidence of introgression in 227 mice from allopatric and sympatric localities in the western United States and northern Mexico. We conducted laboratory mating trials for all species pairs to assess reproductive compatibility, and recorded vocalizations from O. arenicola and O. torridus in sympatry and allopatry to test for evidence of acoustic character displacement. Hybridization was rare in nature and, contrary to prior evidence for O. torridus/O. arenicola hybrids, only involved O. leucogaster and O. arenicola. In contrast, laboratory crosses between O. torridus and O. arenicola produced litters whereas O. leucogaster and O. arenicola crosses did not. Call fundamental frequency in O. torridus and O. arenicola was indistinguishable in allopatry but significantly differentiated in sympatry, a pattern consistent with reproductive character displacement. These results suggest that assortative mating based on a long‐distance signal is an important isolating mechanism between O. torridus and O. arenicola and highlight the importance of behavioral barriers in determining the permeability of species boundaries. 相似文献
55.
Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that modulate target gene expression in response to fatty acid ligands. Their regulation by post-translational modifications has been reported but is poorly understood. In the present study, we investigated whether ligand binding affects the turnover and ubiquitination of the PPARbeta subtype (also known as PPARdelta). Our data show that the ubiquitination and degradation of PPARbeta is not significantly influenced by the synthetic agonist GW501516 under conditions of moderate PPARbeta expression. By contrast, the overexpression of PPARbeta dramatically enhanced its degradation concomitant with its polyubiquitination and the formation of high molecular mass complexes containing multiple, presumably oligomerized PPARbeta molecules that lacked stoichiometical amounts of the obligatory PPARbeta dimerization partner, retinoid X receptor. The formation of these apparently aberrant complexes, as well as the ubiquitination and destabilization of PPARbeta, were strongly inhibited by GW501516. Our findings suggest that PPARbeta is subject to complex post-translational regulatory mechanisms that partly may serve to safeguard the cell against deregulated PPARbeta expression. Furthermore, our data have important implications regarding the widespread use of overexpression systems to evaluate the function and regulation of PPARs. 相似文献
56.
57.
58.
59.
60.
Mairal A Melaine N Laurell H Grober J Holst LS Guillaudeux T Holm C Jégou B Langin D 《Biochemical and biophysical research communications》2002,291(2):286-290
Hormone-sensitive lipase (HSL) is an esterase and lipase, which are essential for spermatogenesis. Two HSL mRNAs are expressed in human testis. A long form is encoded by a testis-specific exon and nine exons common to testis and adipocyte HSL. Here we show that the short-form 3.3-kb mRNA possesses a unique 5' end that is transcribed from a novel testis-specific exon. The corresponding protein is similar to the 775-amino-acid-long adipocyte HSL. Immunohistochemistry experiments on human testis sections revealed that the long form is strictly expressed in haploid germ cells whereas the short form is expressed in interstitial and tubular somatic cells as well as premeiotic germ cells. 相似文献