全文获取类型
收费全文 | 952篇 |
免费 | 91篇 |
国内免费 | 1篇 |
出版年
2023年 | 7篇 |
2022年 | 19篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 29篇 |
2015年 | 43篇 |
2014年 | 61篇 |
2013年 | 61篇 |
2012年 | 83篇 |
2011年 | 84篇 |
2010年 | 44篇 |
2009年 | 39篇 |
2008年 | 64篇 |
2007年 | 45篇 |
2006年 | 51篇 |
2005年 | 54篇 |
2004年 | 54篇 |
2003年 | 57篇 |
2002年 | 45篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1942年 | 1篇 |
排序方式: 共有1044条查询结果,搜索用时 46 毫秒
371.
Tuomas Mattila Suvi Lehtoranta Laura Sokka Matti Melanen Ari Nissinen 《Journal of Industrial Ecology》2012,16(1):51-60
In view of recent studies of the historical development and current status of industrial symbiosis (IS), life cycle assessment (LCA) is proposed as a general framework for quantifying the environmental performance of by‐product exchange. Recent guidelines for LCA (International Reference Life Cycle Data System [ILCD] guidelines) are applied to answer the main research questions in the IS literature reviewed. A typology of five main research questions is proposed: (1) analysis, (2) improvement, and (3) expansion of existing systems; (4) design of new eco‐industrial parks, and (5) restructuring of circular economies. The LCA guidelines were found useful in framing the question and choosing an appropriate reference case for comparison. The selection of a correct reference case reduces the risk of overestimating the benefits of by‐product exchange. In the analysis of existing systems, environmentally extended input‐output analysis (EEIOA) can be used to streamline the analysis and provide an industry average baseline for comparison. However, when large‐scale changes are applied to the system, more sophisticated tools are necessary for assessment of the consequences, from market analysis to general equilibrium modeling and future scenario work. Such a rigorous application of systems analysis was not found in the current IS literature, but would benefit the field substantially, especially when the environmental impact of large‐scale economic changes is analyzed. 相似文献
372.
Chow AM Beraud E Tang DW Ferrier-Pagès C Brown IR 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2012,161(3):349-353
The heat shock protein Hsp60 exhibited marked oscillation during a 12-hour day period when the coral Turbinaria reniformis was maintained in the laboratory under constant conditions of light (200 μE) and temperature (27 °C). A biphasic pattern of Hsp60 was apparent, punctuated by a low protein level at the midpoint of the 12-hour day period. Oscillation of Hsp60 was also apparent when coral was kept in darkness in lieu of a scheduled light period. The pattern of Hsp60 was altered when coral was exposed to increased light intensity (400 μE) or temperature elevation (32 °C). These observations suggest that Hsp60 in coral exhibits oscillation that is altered by increased light and temperature elevation. 相似文献
373.
A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division 总被引:1,自引:0,他引:1
374.
375.
M Kulmala T Petäjä T Nieminen M Sipilä HE Manninen K Lehtipalo M Dal Maso PP Aalto H Junninen P Paasonen I Riipinen KE Lehtinen A Laaksonen VM Kerminen 《Nature protocols》2012,7(9):1651-1667
The formation of new atmospheric aerosol particles and their subsequent growth have been observed frequently at various locations all over the world. The atmospheric nucleation rate (or formation rate) and growth rate (GR) are key parameters to characterize the phenomenon. Recent progress in measurement techniques enables us to measure atmospheric nucleation at the size (mobility diameter) of 1.5 (±0.4) nm. The detection limit has decreased from 3 to 1 nm within the past 10 years. In this protocol, we describe the procedures for identifying new-particle-formation (NPF) events, and for determining the nucleation, formation and growth rates during such events under atmospheric conditions. We describe the present instrumentation, best practices and other tools used to investigate atmospheric nucleation and NPF at a certain mobility diameter (1.5, 2.0 or 3.0 nm). The key instruments comprise devices capable of measuring the number concentration of the formed nanoparticles and their size, such as a suite of modern condensation particle counters (CPCs) and air ion spectrometers, and devices for characterizing the pre-existing particle number concentration distribution, such as a differential mobility particle sizer (DMPS). We also discuss the reliability of the methods used and requirements for proper measurements and data analysis. The time scale for realizing this procedure is 1 year. 相似文献
376.
An inhibition of the Na(+)/K(+)ATPase was previously shown to accompany and potentiate apoptosis in different experimental models. Since TNF-alpha is known to be a pro and anti-apoptotic cytokine, this work was undertaken to study the effect of TNF-alpha on the Na(+)/K(+)ATPase in HepG2 cells and to determine the signaling pathway involved. Cells were incubated for 1 h with TNF-alpha in presence and absence of PDTC, SP600125 and FK009, respective inhibitors of NF-KB, c-JNK, and caspases. The activity of the pump was assayed by measuring the ouabain-inhibitable release of inorganic phosphate, and changes in its expression were monitored by western blot analysis. TNF-alpha decreased significantly the activity and protein expression of the Na(+)/K(+)ATPase. NF-kappaB and caspases were found to be the main effectors of the cytokine, mediating respectively down-regulation and up-regulation of the pump. Their activity was however modulated at 1 h by c-JNK, which stimulated the caspases and inhibited NF-kappaB, resulting in a net inhibition of the ATPase, and probably favoring the apoptotic pathway. 相似文献
377.
378.
379.
Papp A Lahtinen T Härmä M Nuutinen J Uusaro A Alhava E 《Plastic and reconstructive surgery》2006,117(3):889-98; discussion 899-901
380.
Löytynoja A Goldman N 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2008,363(1512):3913-3919
We have developed a phylogeny-aware progressive alignment method that recognizes insertions and deletions as distinct evolutionary events and thus avoids systematic errors created by traditional alignment methods. We now extend this method to simultaneously model regional heterogeneity and evolution. This novel method can be flexibly adapted to alignment of nucleotide or amino acid sequences evolving under processes that vary over genomic regions and, being fully probabilistic, provides an estimate of regional heterogeneity of the evolutionary process along the alignment and a measure of local reliability of the solution. Furthermore, the evolutionary modelling of substitution process permits adjusting the sensitivity and specificity of the alignment and, if high specificity is aimed at, leaving sequences unaligned when their divergence is beyond a meaningful detection of homology. 相似文献