全文获取类型
收费全文 | 924篇 |
免费 | 79篇 |
专业分类
1003篇 |
出版年
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 30篇 |
2014年 | 39篇 |
2013年 | 41篇 |
2012年 | 59篇 |
2011年 | 59篇 |
2010年 | 48篇 |
2009年 | 48篇 |
2008年 | 55篇 |
2007年 | 63篇 |
2006年 | 64篇 |
2005年 | 66篇 |
2004年 | 48篇 |
2003年 | 63篇 |
2002年 | 59篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1971年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有1003条查询结果,搜索用时 15 毫秒
81.
82.
Canal-Raffin M Déridet E Titier K Frakra E Molimard M Moore N 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,814(1):61-67
An ultra-violet high-performance liquid chromatographic method was developed for the determination of sertindole, an atypical antipsychotic drug and its main metabolites dehydrosertindole and norsertindole, in human plasma. With a small sample volume, after a single-step liquid-liquid extraction, the compounds were separated on a reversed-phase XTerra RP(18) column, eluted with 45% of acetonitrile and 55% of ammonium acetate buffer (0.05 M, adjusted pH 8) and detected at 256 nm within 11 min. This method shows a good linearity for plasma concentration between 5-100 ng/ml and 100-1000 ng/ml, a good precision (inter and intra day CV < 11%) and a good inter-assay accuracy (bias < 11%). The limit of quantification concentration was 5 ng/ml. The absolute recovery of sertindole was higher than 99%. This rapid and sensitive method could be used for therapeutic drug monitoring as well as for overdose management. 相似文献
83.
The structure of the epithelia of the branchial chamber organs (gills, branchiostegites, epipodites) and the localization of the Na(+),K(+)-ATPase were investigated in two caridean shrimps, the epibenthic Palaemon adspersus and the deep-sea hydrothermal Rimicaris exoculata. The general organization of the phyllobranchiate gills, branchiostegites and epipodites is similar in P. adspersus and in R. exoculata. The gill filaments are formed by a single axial epithelium made of H-shaped cells with thin lateral expansions and a basal lamina limiting hemolymph lacunae. In P. adspersus, numerous ionocytes are present in the epipodites and in the inner-side of the branchiostegites; immunofluorescence reveals their high content in Na(+),K(+)-ATPase. In R. exoculata, typical ionocytes displaying a strong Na(+),K(+)-ATPase specific fluorescence are observed in the epipodites only. While the epipodites and the branchiostegites appear as the main site of osmoregulation in P. adspersus, only the epipodites might be involved in ion exchanges in R. exoculata. In both species, the gill filaments are mainly devoted to respiration. 相似文献
84.
Ricardo Oliva Joe Win Sylvain Raffaele Laurence Boutemy Tolga O. Bozkurt Angela Chaparro‐Garcia Maria Eugenia Segretin Remco Stam Sebastian Schornack Liliana M. Cano Mireille van Damme Edgar Huitema Marco Thines Mark J. Banfield Sophien Kamoun 《Cellular microbiology》2010,12(6):705-715
Filamentous pathogens, such as plant pathogenic fungi and oomycetes, secrete an arsenal of effector molecules that modulate host innate immunity and enable parasitic infection. It is now well accepted that these effectors are key pathogenicity determinants that enable parasitic infection. In this review, we report on the most interesting features of a representative set of filamentous pathogen effectors and highlight recent findings. We also list and describe all the linear motifs reported to date in filamentous pathogen effector proteins. Some of these motifs appear to define domains that mediate translocation inside host cells. 相似文献
85.
Marianne Schwartz Maria Anvret Mireille Claustres Hans Geir Eiken Kristin Eiklid Charlotte Schaedel Lisa Stolpe Lisbeth Tranebjærg 《Human genetics》1994,93(2):157-161
In a systematic screening for mutations in the gene encoding the cystic fibrosis transmembrane regulator among Danish cystic fibrosis (CF) patients, we identified a mutation in exon 3 (394delTT); this mutation was found to be relatively common in Denmark. We therefore screened for 394delTT in Sweden and Norway, where it turned out to be the second most frequent mutation, accounting for 4% of all CF mutations. It also occurs with a high frequency in Finland, but has not been found in larger surveys of mutations in the CFTR gene. Thus, 394delTT seems to be a specific Nordic CF mutation. 相似文献
86.
Sulfide (H2S) is an inhibitor of mitochondrial cytochrome oxidase comparable to cyanide. In this study, poisoning of cells was observed with sulfide concentrations above 20 µM. Sulfide oxidation has been shown to take place in organisms/cells naturally exposed to sulfide. Sulfide is released as a result of metabolism of sulfur containing amino acids. Although in mammals sulfide exposure is not thought to be quantitatively important outside the colonic mucosa, our study shows that a majority of mammalian cells, by means of the mitochondrial sulfide quinone reductase (SQR), avidly consume sulfide as a fuel. The SQR activity was found in mitochondria isolated from mouse kidneys, liver, and heart. We demonstrate the precedence of the SQR over the mitochondrial complex I. This explains why the oxidation of the mineral substrate sulfide takes precedence over the oxidation of other (carbon-based) mitochondrial substrates. Consequently, if sulfide delivery rate remains lower than the SQR activity, cells maintain a non-toxic sulfide concentration (< 1 µM) in their external environment. In the colonocyte cell line HT-29, sulfide oxidation provided the first example of reverse electron transfer in living cells, such a transfer increasing sulfide tolerance. However, SQR activity was not detected in brain mitochondria and neuroblastoma cells. Consequently, the neural tissue would be more sensitive to sulfide poisoning. Our data disclose new constraints concerning the emerging signaling role of sulfide. 相似文献
87.
88.
Mireille Faist Emmenegger Matthias Stucki Sandra Hermle 《The International Journal of Life Cycle Assessment》2012,17(9):1142-1147
Introduction
In the last years, the use of biomass for energy purposes has been seen as a promising option to reduce the use of nonrenewable energy sources and the emissions of fossil carbon. However, LCA studies have shown that the energetic use of biomass also causes impacts on climate change and, furthermore, that different environmental issues arise, such as land use and agricultural emissions. While biomass is renewable, it is not an unlimited resource. Its use, to whatever purpose, must therefore be well studied to promote the most efficient option with the least environmental impacts. The 47th LCA Discussion Forum gathered several national and international speakers who provided a broad and qualified view on the topic.Summary of the topics presented in DF 47
Several aspects of energetic biomass use from a range of projects financed by the Swiss Federal Office of Energy (SFOE) were presented in this Discussion Forum. The first session focused on important aspects of the agricultural biogas production like the use of high energy crops or catch crops as well as the influence of plant size on the environmental performance of biogas. In the second session, other possibilities of biomass treatment like direct combustion, composting, and incineration with municipal waste were presented. Topic of the first afternoon session was the update and harmonization of biomass inventories and the resulting new assessment of biofuels. The short presentations investigated some further aspects of the LCA of bioenergy like the assessment of spatial variation of greenhouse gas (GHG) emissions from bioenergy production in a country, the importance of indirect land use change emissions on the overall results, the assessment of alternative technologies to direct spreading of digestate or the updates of the car operation datasets in ecoinvent.Conclusions
One main outcome of this Discussion Forum is that bioenergy is not environmentally friendly per se. In many cases, energetic use of biomass allows a reduction of GHG and fossil energy use. However, there is often a tradeoff with other environmental impacts linked to agricultural production like eutrophication or ecotoxicity. Methodological challenges still exist, like the assessment of direct and indirect land use change emissions and their attribution to the bioenergy production, or the influence of heavy metal flows on the bioenergy assessment. Another challenge is the implementation of a life cycle approach in certification or legislation schemes, as shown by the example of the Renewable Energy Directive of the European Union. 相似文献89.
90.
In situ hybridization of cloned rRNA genes from Drosophila melanogaster to D. simulans metaphase chromosomes shows that in the tested wild type strains both sex chromosomes contain a nucleolus organizer region. Silver grain counts support the published data that the X chromosomal rRNA gene number is significantly higher than the Y chromosomal. 相似文献