全文获取类型
收费全文 | 5111篇 |
免费 | 410篇 |
国内免费 | 7篇 |
出版年
2023年 | 23篇 |
2022年 | 43篇 |
2021年 | 85篇 |
2020年 | 51篇 |
2019年 | 59篇 |
2018年 | 76篇 |
2017年 | 71篇 |
2016年 | 129篇 |
2015年 | 214篇 |
2014年 | 225篇 |
2013年 | 291篇 |
2012年 | 386篇 |
2011年 | 374篇 |
2010年 | 220篇 |
2009年 | 220篇 |
2008年 | 298篇 |
2007年 | 308篇 |
2006年 | 254篇 |
2005年 | 289篇 |
2004年 | 259篇 |
2003年 | 258篇 |
2002年 | 231篇 |
2001年 | 67篇 |
2000年 | 71篇 |
1999年 | 76篇 |
1998年 | 65篇 |
1997年 | 44篇 |
1996年 | 34篇 |
1995年 | 55篇 |
1994年 | 56篇 |
1993年 | 44篇 |
1992年 | 44篇 |
1991年 | 46篇 |
1990年 | 38篇 |
1989年 | 46篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 25篇 |
1985年 | 41篇 |
1984年 | 27篇 |
1983年 | 31篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1973年 | 14篇 |
1971年 | 15篇 |
1970年 | 10篇 |
1965年 | 10篇 |
排序方式: 共有5528条查询结果,搜索用时 15 毫秒
121.
Mihalis N. Mindrinos William H. Petri Vasilis K. Galanopoulos Mary F. Lombard Lukas H. Margaritis 《Development genes and evolution》1980,189(3):187-196
Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components. 相似文献
122.
123.
124.
125.
126.
Yaoqi Li Peter B. Reich Bernhard Schmid Nawal Shrestha Xiao Feng Tong Lyu Brian S. Maitner Xiaoting Xu Yichao Li Dongting Zou Zheng‐Hong Tan Xiangyan Su Zhiyao Tang Qinghua Guo Xiaojuan Feng Brian J. Enquist Zhiheng Wang 《Ecology letters》2020,23(6):1003-1013
A key challenge in ecology is to understand the relationships between organismal traits and ecosystem processes. Here, with a novel dataset of leaf length and width for 10 480 woody dicots in China and 2374 in North America, we show that the variation in community mean leaf size is highly correlated with the variation in climate and ecosystem primary productivity, independent of plant life form. These relationships likely reflect how natural selection modifies leaf size across varying climates in conjunction with how climate influences canopy total leaf area. We find that the leaf size?primary productivity functions based on the Chinese dataset can predict productivity in North America and vice‐versa. In addition to advancing understanding of the relationship between a climate‐driven trait and ecosystem functioning, our findings suggest that leaf size can also be a promising tool in palaeoecology for scaling from fossil leaves to palaeo‐primary productivity of woody ecosystems. 相似文献
127.
Fabiola Marín‐Aguilar Ana V. Lechuga‐Vieco Elísabet Alcocer‐Gmez Beatriz Castejn‐Vega Javier Lucas Carlos Garrido Alejandro Peralta‐Garcia Antonio J. Prez‐Pulido Alfonso Varela‐Lpez Jos L. Quiles Bernhard Ryffel Ignacio Flores Pedro Bulln Jesús Ruiz‐Cabello Mario D. Cordero 《Aging cell》2020,19(1)
While NLRP3‐inflammasome has been implicated in cardiovascular diseases, its role in physiological cardiac aging is largely unknown. During aging, many alterations occur in the organism, which are associated with progressive impairment of metabolic pathways related to insulin resistance, autophagy dysfunction, and inflammation. Here, we investigated the molecular mechanisms through which NLRP3 inhibition may attenuate cardiac aging. Ablation of NLRP3‐inflammasome protected mice from age‐related increased insulin sensitivity, reduced IGF‐1 and leptin/adiponectin ratio levels, and reduced cardiac damage with protection of the prolongation of the age‐dependent PR interval, which is associated with atrial fibrillation by cardiovascular aging and reduced telomere shortening. Furthermore, old NLRP3 KO mice showed an inhibition of the PI3K/AKT/mTOR pathway and autophagy improvement, compared with old wild mice and preserved Nampt‐mediated NAD+ levels with increased SIRT1 protein expression. These findings suggest that suppression of NLRP3 prevented many age‐associated changes in the heart, preserved cardiac function of aged mice and increased lifespan. 相似文献
128.
129.
Comparing diversity levels in environmental samples: DNA sequence capture and metabarcoding approaches using 18S and COI genes 总被引:1,自引:0,他引:1
Hendrik Giebner Kathrin Langen Sarah J. Bourlat Sandra Kukowka Christoph Mayer Jonas J. Astrin Bernhard Misof Vera G. Fonseca 《Molecular ecology resources》2020,20(5):1333-1345
Environmental DNA studies targeting multiple taxa using metabarcoding provide remarkable insights into levels of species diversity in any habitat. The main drawbacks are the presence of primer bias and difficulty in identifying rare species. We tested a DNA sequence‐capture method in parallel with the metabarcoding approach to reveal possible advantages of one method over the other. Both approaches were performed using the same eDNA samples and the same 18S and COI regions, followed by high throughput sequencing. Metabarcoded eDNA libraries were PCR amplified with one primer pair from 18S and COI genes. DNA sequence‐capture libraries were enriched with 3,639 baits targeting the same gene regions. We tested amplicon sequence variants (ASVs) and operational taxonomic units (OTUs) in silico approaches for both markers and methods, using for this purpose the metabarcoding data set. ASVs methods uncovered more species for the COI gene, whereas the opposite occurred for the 18S gene, suggesting that clustering reads into OTUs could bias diversity richness especially using 18S with relaxed thresholds. Additionally, metabarcoding and DNA sequence‐capture recovered 80%–90% of the control sample species. DNA sequence‐capture was 8x more expensive, nonetheless it identified 1.5x more species for COI and 13x more genera for 18S than metabarcoding. Both approaches offer reliable results, sharing ca. 40% species and 72% families and retrieve more taxa when nuclear and mitochondrial markers are combined. eDNA metabarcoding is quite well established and low‐cost, whereas DNA‐sequence capture for biodiversity assessment is still in its infancy, is more time‐consuming but provides more taxonomic assignments. 相似文献