全文获取类型
收费全文 | 3162篇 |
免费 | 213篇 |
出版年
2023年 | 26篇 |
2022年 | 70篇 |
2021年 | 102篇 |
2020年 | 85篇 |
2019年 | 87篇 |
2018年 | 128篇 |
2017年 | 125篇 |
2016年 | 147篇 |
2015年 | 199篇 |
2014年 | 222篇 |
2013年 | 212篇 |
2012年 | 234篇 |
2011年 | 223篇 |
2010年 | 145篇 |
2009年 | 111篇 |
2008年 | 155篇 |
2007年 | 146篇 |
2006年 | 124篇 |
2005年 | 133篇 |
2004年 | 99篇 |
2003年 | 106篇 |
2002年 | 75篇 |
2001年 | 54篇 |
2000年 | 50篇 |
1999年 | 35篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 5篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1976年 | 14篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1971年 | 5篇 |
排序方式: 共有3375条查询结果,搜索用时 93 毫秒
121.
Birong Zhang James R. Kiefer Robert A. Blake Jae H. Chang Steven Hartman Ellen Rei Ingalla Tracy Kleinheinz Vidhi Mody Michelle Nannini Daniel F. Ortwine Yingqing Ran Amy Sambrone Deepak Sampath Maia Vinogradova Yu Zhong Jerome C. Nwachukwu Kendall W. Nettles Tommy Lai Jun Liang 《Bioorganic & medicinal chemistry letters》2019,29(7):905-911
Despite tremendous progress made in the understanding of the ERα signaling pathway and the approval of many therapeutic agents, ER+?breast cancer continues to be a leading cause of cancer death in women. We set out to discover compounds with a dual mechanism of action in which they not only compete with estradiol for binding with ERα, but also can induce the degradation of the ERα protein itself. We were attracted to the constrained chromenes containing a tetracyclic benzopyranobenzoxepine scaffold, which were reported as potent selective estrogen receptor modulators (SERMs). Incorporation of a fluoromethyl azetidine side chain yielded highly potent and efficacious selective estrogen receptor degraders (SERDs), such as 16aa and surprisingly, also its enantiomeric pair 16ab. Co-crystal structures of the enantiomeric pair 16aa and 16ab in complex with ERα revealed default (mimics the A-D rings of endogenous ligand estradiol) and core-flipped binding modes, rationalizing the equivalent potency observed for these enantiomers in the ERα degradation and MCF-7 anti-proliferation assays. 相似文献
122.
123.
Mutel Chris Liao Xun Patouillard Laure Bare Jane Fantke Peter Frischknecht Rolf Hauschild Michael Jolliet Olivier Maia de Souza Danielle Laurent Alexis Pfister Stephan Verones Francesca 《The International Journal of Life Cycle Assessment》2019,24(5):856-865
The International Journal of Life Cycle Assessment - Regionalized life cycle impact assessment (LCIA) has rapidly developed in the past decade, though its widespread application, robustness, and... 相似文献
124.
125.
Úrsula Maria C. Bastos Ivone de Andrade Rosa John D. Teixeira Graciele Gonalves Manoel L. Costa Luis Eduardo M. Quintas Claudia Mermelstein 《Cell biology international》2019,43(12):1425-1434
β‐Adrenergic signaling regulates many physiological processes in skeletal muscles. A wealth of evidence has shown that β‐agonists can increase skeletal muscle mass in vertebrates. Nevertheless, to date, the specific role of β‐adrenergic receptors in different cell phenotypes (myoblasts, fibroblasts, and myotubes) and during the different steps of embryonic skeletal muscle differentiation has not been studied. Therefore, here we address this question through the analysis of embryonic chick primary cultures of skeletal muscle cells during the formation of multinucleated myotubes. We used isoproterenol (ISO), a β‐adrenergic receptor agonist, to activate the β‐adrenergic signaling and quantified several aspects of muscle differentiation. ISO induced an increase in myoblast proliferation, in the percentage of Pax7‐positive myoblasts and in the size of skeletal muscle fibers, suggesting that ISO activates a hyperplasic and hypertrophic muscle response. Interestingly, treatment with ISO did not alter the number of fibroblast cells, suggesting that ISO effects are specific to muscle cells in the case of chick myogenic cell culture. We also show that rapamycin, an inhibitor of the mammalian target of rapamycin signaling pathway, did not prevent the effects of ISO on chick muscle fiber size. The collection of these results provides new insights into the role of β‐adrenergic signaling during skeletal muscle proliferation and differentiation and specifically in the regulation of skeletal muscle hyperplasia and hypertrophy. 相似文献
126.
127.
Gabriella Mamede Andrade Monalisa Medrado Bomfim Maite del Collado Flvio Vieira Meirelles Felipe Perecin Juliano Coelho da Silveira 《Molecular reproduction and development》2019,86(8):1067-1080
The biotechnology for in vitro embryo production is becoming increasingly popular, being applied to humans and domestic animals. Embryo development can be achieved with either 20% or 5% oxygen tension. The extracellular vesicles (EVs) are secreted by different cell types and carry bioactive materials. Our objective was to determine the secretion pattern and micro RNA (miRNA) contents of EVs released in the bovine embryo culture environment—embryo and cumulus cell monolayer—on Days 3 and 7 of in vitro culture under two different oxygen tensions: High (20%) and low (5%). The EVs were isolated from the medium and analyzed to determine size, concentration, and miRNA levels. EVs concentration in low oxygen tension increased on Day 3 and decreased on Day 7. Additionally, altered EV miRNAs derived from the embryo‐cumulus culture medium were predicted to regulate survival and proliferation‐related pathways on Days 3 and 7. Moreover, miR‐210 levels decreased in EVs isolated from the culture medium under high oxygen tension suggesting that this miRNA can be used as a marker for normoxia since it is associated with low oxygen tension. In summary, this study provides knowledge of the oxygen tension effects on EVs release and content, and potentially, on cell‐to‐cell communication during in vitro bovine embryo production. 相似文献
128.
129.
Kelly G. Aukema Mian Wang Beatriz de Souza Sophie O'Keane Maia Clipsham Lawrence P. Wackett Alptekin Aksan 《Microbial biotechnology》2022,15(9):2391-2400
Engineered materials to improve the shelf-life of desiccated microbial strains are needed for cost-effective bioaugmentation strategies. High temperatures and humidity of legume-growing regions challenge long-term cell stabilization at the desiccated state. A thermostable xeroprotectant core and hydrophobic water vapour barrier shell encapsulation technique was developed to protect desiccated cells from the environment. A trehalose core matrix increased the stability of desiccated Bradyrhizobium by three orders of magnitude over 20 days at 32°C and 50% relative humidity (RH) compared to buffer alone; however, the improvement was not deemed sufficient for a shelf-stable bioproduct. We tested common additives (skim milk, albumin, gelatin and dextran) to increase the glass transition temperature of the desiccated product to provide further stabilization. Albumin increased the glass transition temperature of the trehalose-based core by 40°C and stabilized desiccated Bradyrhizobium for 4 months during storage at high temperature (32°C) and moderate humidity (50% RH) with only 1 log loss of viability. Although the albumin-trehalose core provided exceptional protection against high temperature, it was ineffective at higher humidity conditions (75%). We therefore incorporated a paraffin shell, which protected desiccated cells against 75% RH providing proof of concept that core and shell encapsulation is an effective strategy to stabilize desiccated cells. 相似文献
130.
Gledson V. Bianconi Sandra B. Mikich Sirlei D. Teixeira Beatriz Helena L.N.S. Maia 《Biotropica》2007,39(1):136-140
Previous tests with essential oils from ripe chiropterochoric fruits suggested they can be used to attract and capture fruit-eating bats inside forest remnants. Here we evaluated the efficiency of these oils to attract frugivorous bats to open areas. We performed field tests with artificial fruits impregnated with essential oils of the genera Piper or Ficus that were attached to two groups of mist-nets set 50 m outside the border of a forest remnant. One group of artificial fruits received the corresponding oil isolated through hydrodistillation and the other received water only. Fruits with oils attracted significantly more fruit-eating bats, especially Artibeus lituratus that regularly crosses open habitats to reach other forest remnants. The highly significant attraction of A. lituratus by the oil of Piper was unexpected, since this bat is a specialist on Ficus fruits. We hypothesize that in habitats with no fruit available it is possible to attract frugivorous bats with the odor of several ripe fruit species. Furthermore, we verified that almost half of the individuals captured defecated seeds, indicating that the oils also attract recently fed bats, even when their preferred food is available nearby. This technique potentially may increase seed rain at specific locations, being particularly promising to restoration projects. 相似文献