全文获取类型
收费全文 | 1438篇 |
免费 | 97篇 |
专业分类
1535篇 |
出版年
2023年 | 5篇 |
2022年 | 18篇 |
2021年 | 32篇 |
2020年 | 24篇 |
2019年 | 20篇 |
2018年 | 32篇 |
2017年 | 21篇 |
2016年 | 34篇 |
2015年 | 69篇 |
2014年 | 78篇 |
2013年 | 103篇 |
2012年 | 132篇 |
2011年 | 118篇 |
2010年 | 86篇 |
2009年 | 74篇 |
2008年 | 92篇 |
2007年 | 100篇 |
2006年 | 97篇 |
2005年 | 86篇 |
2004年 | 91篇 |
2003年 | 76篇 |
2002年 | 59篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1982年 | 1篇 |
排序方式: 共有1535条查询结果,搜索用时 15 毫秒
51.
This paper comprises the scientific justification for the Farm Constructed Wetland (FCW) Design Manual for Northern Ireland and Scotland. Moreover, this document addresses an international audience interested in applying wetland systems in the wider agricultural context. Farm constructed wetlands combine farm wastewater (predominantly farmyard runoff) treatment with landscape and biodiversity enhancements, and are a specific application and class of integrated constructed wetlands (ICW), which have wider applications in the treatment of other wastewater types such as domestic sewage. The aim of this review paper is to propose guidelines highlighting the rationale for FCW, including key water quality management and regulatory issues, important physical and biochemical wetland treatment processes, assessment techniques for characterizing potential FCW sites and discharge options to water bodies. The paper discusses universal design, construction, planting, maintenance and operation issues relevant specifically for FCW in a temperate climate, but highlights also catchment-specific requirements to protect the environment. 相似文献
52.
Olivier Dangles Thomas Steinmann Dominique Pierre Fabrice Vannier Jérôme Casas 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(7):653-663
Understanding the relative contributions of the shape of a sensory organ and the arrangement of receptors to the overall performance of the organ has long been a challenge for sensory biologists. We tackled this issue using the wind-sensing system of crickets, the cerci, two conical abdominal appendages covered with arrays of filiform hairs. Scanning electron microscopy coupled with 3D reconstruction methods were used for mapping of all cercal filiform hairs. The hairs are arranged according to their diameter in a way that avoids collisions with neighbours during hair deflection: long hairs are regularly spaced, whereas short hairs are both randomly and densely distributed. Particle image velocimetry showed that the variation in diameter of the cercus along its length modifies the pattern of fluid velocities. Hairs are subject to higher air flow amplitudes at the base than at the apex of the cercus. The relative importance of interactions between receptors and the air flow around the organ may explain the performance of the cricket's cercal system: it is characterised by a high density of statistically non-interacting short hairs located at the base of the cercus where sensitivity to air currents is the highest. 相似文献
53.
The influence of anionic lipids on SHIP2 phosphatidylinositol 3,4,5-trisphosphate 5-phosphatase activity 总被引:1,自引:0,他引:1
The SH2 domain containing inositol 5-phosphatase 2 (SHIP2) catalyzes the dephosphorylation of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) to phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P2) and participates in the insulin signalling pathway in vivo. In a comparative study of SHIP2 and the phosphatase and tensin homologue deleted on chromosome 10 (PTEN), we found that their lipid phosphatase activity was influenced by the presence of vesicles of phosphatidylserine (PtdSer). SHIP2 PtdIns(3,4,5)P3 5-phosphatase activity was greatly stimulated in the presence of vesicles of PtdSer. This effect appears to be specific for di-C8 and di-C16 fatty acids of PtdIns(3,4,5)P3 as substrate. It was not observed with inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) another in vitro substrate of SHIP2, nor with Type I Ins(1,4,5)P3/Ins(1,3,4,5)P4 5-phosphatase activity, an enzyme which acts on soluble inositol phosphates. Vesicles of phosphatidylcholine (PtdCho) stimulated only twofold PtdIns(3,4,5)P3 5-phosphatase activity of SHIP2. Both a minimal catalytic construct and the full length SHIP2 were sensitive to the stimulation by PtdSer. In contrast, PtdIns(3,4,5)P3 5-phosphatase activity of the Skeletal muscle and Kidney enriched Inositol Phosphatase (SKIP), another member of the mammaliam Type II phosphoinositide 5-phosphatases, was not sensitive to PtdSer. Our enzymatic data establish a specificity in the control of SHIP2 lipid phosphatase activity with PtdIns(3,4,5)P3 as substrate which is depending on the fatty acid composition of the substrate. 相似文献
54.
Asma Alinsafi Nouceiba Adouani Fabrice Bline Thomas Lendormi Lionel Limousy Olivier Sire 《Process Biochemistry》2008,43(6):683-689
Laboratory-scale experiments were conducted to examine the N2O emission during the denitrification process. For each of the 6 runs carried out, synthetic effluent was fed in a 10 l batch mixed liquor to investigate the effect of nitrite on N2O emission and Helium was continuously bubbled through the reactor at constant rate (0.12 l/min) to favour N2O transfer and detection. An increasing COD/NO3−-N influent ratio from 3 to 7 was firstly applied (runs 1–3). Secondly, NO2− pulse additions were performed during run 4 and 5 (10 and 20 mg N/l, respectively). Finally, the reactor was fed with influent containing both NO2− and NO3−. We showed that N2O emission was detected shortly after NO2− accumulation, few minutes after the substrate feeding. The highest emission occurred at the lower COD/NO3−-N ratio (=3) and at the higher NO2− addition (20 mg N/l). In addition, the higher nitrogen conversion to N2O gas (14.4%) was obtained with an influent containing initially both NO2− and NO3−. Our results suggest a direct effect of the NO2− concentration on the N2O emission. We have also confirmed the inhibitory effect of NO2− concentration on N2O reduction. 相似文献
55.
Deutsch EW Ball CA Berman JJ Bova GS Brazma A Bumgarner RE Campbell D Causton HC Christiansen JH Daian F Dauga D Davidson DR Gimenez G Goo YA Grimmond S Henrich T Herrmann BG Johnson MH Korb M Mills JC Oudes AJ Parkinson HE Pascal LE Pollet N Quackenbush J Ramialison M Ringwald M Salgado D Sansone SA Sherlock G Stoeckert CJ Swedlow J Taylor RC Walashek L Warford A Wilkinson DG Zhou Y Zon LI Liu AY True LD 《Nature biotechnology》2008,26(3):305-312
One purpose of the biomedical literature is to report results in sufficient detail that the methods of data collection and analysis can be independently replicated and verified. Here we present reporting guidelines for gene expression localization experiments: the minimum information specification for in situ hybridization and immunohistochemistry experiments (MISFISHIE). MISFISHIE is modeled after the Minimum Information About a Microarray Experiment (MIAME) specification for microarray experiments. Both guidelines define what information should be reported without dictating a format for encoding that information. MISFISHIE describes six types of information to be provided for each experiment: experimental design, biomaterials and treatments, reporters, staining, imaging data and image characterizations. This specification has benefited the consortium within which it was developed and is expected to benefit the wider research community. We welcome feedback from the scientific community to help improve our proposal. 相似文献
56.
Sylvain de
Breyne Caroline Vindry Olivia Guillin Lionel Cond Fabrice Mure Henri Gruffat Laurent Chavatte Thophile Ohlmann 《Nucleic acids research》2020,48(22):12502
Coronaviruses represent a large family of enveloped RNA viruses that infect a large spectrum of animals. In humans, the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic and is genetically related to SARS-CoV and Middle East respiratory syndrome-related coronavirus (MERS-CoV), which caused outbreaks in 2002 and 2012, respectively. All viruses described to date entirely rely on the protein synthesis machinery of the host cells to produce proteins required for their replication and spread. As such, virus often need to control the cellular translational apparatus to avoid the first line of the cellular defense intended to limit the viral propagation. Thus, coronaviruses have developed remarkable strategies to hijack the host translational machinery in order to favor viral protein production. In this review, we will describe some of these strategies and will highlight the role of viral proteins and RNAs in this process. 相似文献
57.
Laïos I Journe F Laurent G Nonclercq D Toillon RA Seo HS Leclercq G 《The Journal of steroid biochemistry and molecular biology》2003,87(2-3):207-221
This study aimed at a better understanding of estrogen receptor alpha (ER) up regulation induced by partial estrogen antagonists. Effect of treatment with hydroxytamoxifen (OH-Tam) on ER level in MCF-7 cells was investigated by an approach combining ER measurement (enzyme immunoassay) and morphological demonstration (immunofluorescence). Furthermore, the influence of drug exposure on the rates of ER synthesis and degradation was assessed by determining [35S]methionine incorporated into the receptor in different experimental conditions (measurement of synthesis or pulse-chase experiments). ER up regulation was already induced by a 1-h pulse treatment with OH-Tam, thus a continuous exposure was not required. This process appeared reversible (i.e. ER accumulation due to OH-Tam rapidly vanished upon subsequent exposure to 17beta-estradiol (E2) or the pure antiestrogen RU 58668). While OH-Tam did not affect the rate of [35S]methionine incorporation into ER, it clearly caused an impairment of ER degradation (pulse-chase experiments) indicating that up regulation results from a stabilization of the receptor associated with the maintenance of its synthesis. Various tamoxifen derivatives, as well as a few related partial antiestrogens, were compared on the basis of binding ability and propensity to induce ER up regulation. A close relationship was found between both properties. Structure-activity analysis revealed that the capacity of these compounds to induce ER up regulation is associated with characteristics of their aminoalkyle side-chain, similar to those required for antiestrogenicity. 相似文献
58.
Jérémy Gauthier Joana Meier Fabrice Legeai Melanie McClure Annabel Whibley Anthony Bretaudeau Hélène Boulain Hugues Parrinello Sam T. Mugford Richard Durbin Chenxi Zhou Shane McCarthy Christopher W. Wheat Florence Piron-Prunier Christelle Monsempes Marie-Christine François Paul Jay Camille Noûs Emma Persyn Emmanuelle Jacquin-Joly Camille Meslin Nicolas Montagné Claire Lemaitre Marianne Elias 《Molecular ecology resources》2023,23(4):872-885
The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies. 相似文献
59.