全文获取类型
收费全文 | 5276篇 |
免费 | 524篇 |
专业分类
5800篇 |
出版年
2022年 | 41篇 |
2021年 | 85篇 |
2020年 | 49篇 |
2019年 | 57篇 |
2018年 | 57篇 |
2017年 | 59篇 |
2016年 | 123篇 |
2015年 | 234篇 |
2014年 | 249篇 |
2013年 | 289篇 |
2012年 | 406篇 |
2011年 | 390篇 |
2010年 | 229篇 |
2009年 | 219篇 |
2008年 | 331篇 |
2007年 | 276篇 |
2006年 | 282篇 |
2005年 | 289篇 |
2004年 | 290篇 |
2003年 | 255篇 |
2002年 | 284篇 |
2001年 | 64篇 |
2000年 | 39篇 |
1999年 | 52篇 |
1998年 | 74篇 |
1997年 | 44篇 |
1996年 | 47篇 |
1995年 | 53篇 |
1994年 | 51篇 |
1993年 | 44篇 |
1992年 | 33篇 |
1991年 | 36篇 |
1990年 | 49篇 |
1989年 | 30篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 29篇 |
1985年 | 41篇 |
1984年 | 46篇 |
1983年 | 45篇 |
1982年 | 35篇 |
1981年 | 48篇 |
1980年 | 40篇 |
1979年 | 35篇 |
1978年 | 27篇 |
1977年 | 37篇 |
1976年 | 29篇 |
1974年 | 30篇 |
1973年 | 28篇 |
1972年 | 27篇 |
排序方式: 共有5800条查询结果,搜索用时 15 毫秒
121.
There has been substantial interest of late in using population genetic methods to study sexual conflict, where an allele increases the fitness of one sex at some cost to the other (Mank, 2017). Population genomic scans for sexual conflict offer an important advance given the difficulties of identifying antagonistic alleles from more traditional methods, and could greatly increase our understanding of the extent and loci of sexual conflict. This is particularly true for studies in natural populations, for which obtaining accurate fitness measurements for each sex can be challenging. In this issue of Molecular Ecology, Bissegger, Laurentino, Roesti, and Berner (2019) present a cautionary tale about how to interpret these population genomic data. 相似文献
122.
Feng Yang Robert T Todd Anna Selmecki Yuan-ying Jiang Yong-bing Cao Judith Berman 《Genetics》2021,218(2)
Candida albicans is a prevalent human fungal pathogen. Rapid genomic change, due to aneuploidy, is a common mechanism that facilitates survival from multiple types of stresses including the few classes of available antifungal drugs. The stress survival of aneuploids occurs despite the fitness costs attributed to most aneuploids growing under idealized lab conditions. Systematic study of the aneuploid state in C. albicans has been hindered by the lack of a comprehensive collection of aneuploid strains. Here, we describe a collection of diploid C. albicans aneuploid strains, each carrying one extra copy of each chromosome, all from the same genetic background. We tested the fitness of this collection under several physiological conditions including shifts in pH, low glucose, oxidative stress, temperature, high osmolarity, membrane stress, and cell wall stress. We found that most aneuploids, under most conditions, were less fit than their euploid parent, yet there were specific conditions under which specific aneuploid isolates provided a fitness benefit relative to the euploid parent strain. Importantly, this fitness benefit was attributable to the change in the copy number of specific chromosomes. Thus, C. albicans can tolerate aneuploidy of each chromosome and some aneuploids confer improved growth under conditions that the yeast encounters in its host niches. 相似文献
123.
124.
125.
126.
Jardón-Valadez Eduardo Chen Charles H. García-Garibay Mariano Jiménez-Guzmán Judith Ulmschneider Martin B. 《Food biophysics》2021,16(1):70-83
Food Biophysics - Absorption of bioactive peptides in the intestinal epithelium take place in the apical or the basolateral tight junctions of the cells. Depending on the peptide size and... 相似文献
127.
Disturbed natural areas frequently experience invasion by introduced plant species that can reduce native biodiversity. Biological control can suppress these introduced species, but without restoration another introduced species can invade. Integration of biological control with concurrent revegetation can both aid in weed reduction via interspecific plant competition and establish a restored native plant community. This 3‐year study investigated an integrated approach to controlling the introduced annual Mile‐a‐minute weed (Persicaria perfoliata [L.] H. Gross [Polygonaceae]) using the biocontrol weevil Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) and restoration planting using a native seed mix. A fully factorial design tested weevils and seeding, separately and together, using insecticide to eliminate weevils. The weevils together with the native seed mix reduced P. perfoliata percent cover in 2009 and 2010, and peak seed cluster production in 2010, compared to the insecticide ? no seed control treatment. Persicaria perfoliata final dry biomass was reduced by 75% in 2010 and by 57% in 2011 in the weevils plus seed treatment compared to the control, with weevils having the greatest effect in 2010 and the seed treatment having the greatest impact in 2011. Results suggest an additive effect of biocontrol and seeding in suppressing P. perfoliata. Seeded treatments also developed the highest native plant species richness and diversity, comprised of spontaneous recolonization in addition to species from the seed mix. Results support the use of integrated management of this invasive weed, with suppression through biological control and native revegetation together helping prevent reinvasion while restoring native plant biodiversity. 相似文献
128.
José Correa-Basurto Judith Espinosa-Raya Mario González-May L. Michel Espinoza-Fonseca Iván Vázquez-Alcántara José Trujillo-Ferrara 《Journal of enzyme inhibition and medicinal chemistry》2013,28(2):133-138
Two arylderivatives, 3a-Acetoxy-5H-pyrrolo(1,2-a) (3,1)benzoxazin-1,5-(3aH)-dione 3 and cis-N-p-Acetoxy-phenylisomaleimide 4, were synthesized from anthranilic acid and para-aminophenol, respectively. The inhibitory effects of these compounds on acetylcholinesterase (AChE) activity were evaluated in vitro as well as by docking simulations. Both compounds showed inhibition of AChE activity (Ki = 4.72 ± 2.3 μM for 3 and 3.6 ± 1.8 μM for 4) in in vitro studies. Moreover, they behaved as irreversible inhibitors and made π–π interaction with W84 and hydrogen bonded with S200 and Y337 according to experimental data and docking calculations. The docking calculations showed ΔG bind (kcal/mol) of ? 9.22 for 3 and ? 8.58 for 4. These two compounds that can be use as leads for a new family of anti-Alzheimer disease drugs. 相似文献
129.
Judith Barends Johannes B. van der Linden Floris L. Van Delft Gerrit-Jan Koomen 《Nucleosides, nucleotides & nucleic acids》2013,32(9):2121-2126
Abstract Room-temperature treatment of persilylated 6-chloro-9-β-D-ribofuranosyl-purine with a variety of aliphatic and aromatic amines, in the presence of Pd2(dba)3, BINAP and base, leads to N6-substituted adenosine analogues in fair to good yields. Coupling of chloropurine with a chiral aziridinyl diester is applied in the synthesis of a potential adenylosuccinate lyase inhibitor. 相似文献
130.
Bhakti B. Salgaonkar Kabilan Mani Judith Maria Bragança 《Extremophiles : life under extreme conditions》2013,17(5):787-795
Extremely halophilic archaeal isolates obtained from brine and sediment samples of solar salterns of Goa and Tamil Nadu, India were screened for accumulation of polyhydroxyalkanoates (PHA). Seven polymer accumulating haloarchaeal strains (TN4, TN5, TN6, TN7, TN9, TN10 and BBK2) were selected based on their growth and intensity of fluorescence when grown on 20 % NaCl synthetic medium supplemented with 2 % glucose and incorporated with Nile red dye. The polymer was quantified by conversion of PHA to crotonic acid which gave a characteristic absorption maxima at 235 nm. On the basis of phenotypic and genotypic characterization the cultures TN4, TN5, TN6, TN7, TN10 and BBK2 were grouped under genus Haloferax whereas isolate TN9 was grouped under the genus Halogeometricum. Growth kinetics and polymer accumulation studies revealed that the culture Halogeometricum borinquense strain TN9 accumulates PHA maximally at the mid-log phase, i.e. 5th day of growth (approx. 14 wt% PHA of CDW). Analysis of the polymer by IR, 1H NMR and 13C NMR confirmed it to be a homopolymer of 3-hydroxybutyrate. 相似文献