全文获取类型
收费全文 | 981篇 |
免费 | 73篇 |
国内免费 | 315篇 |
出版年
2024年 | 9篇 |
2023年 | 62篇 |
2022年 | 56篇 |
2021年 | 82篇 |
2020年 | 51篇 |
2019年 | 59篇 |
2018年 | 51篇 |
2017年 | 45篇 |
2016年 | 43篇 |
2015年 | 21篇 |
2014年 | 57篇 |
2013年 | 76篇 |
2012年 | 43篇 |
2011年 | 51篇 |
2010年 | 26篇 |
2009年 | 57篇 |
2008年 | 66篇 |
2007年 | 66篇 |
2006年 | 44篇 |
2005年 | 56篇 |
2004年 | 39篇 |
2003年 | 34篇 |
2002年 | 21篇 |
2001年 | 29篇 |
2000年 | 15篇 |
1999年 | 22篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1995年 | 21篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1369条查询结果,搜索用时 46 毫秒
101.
102.
Chernyh NA Gavrilov SN Sorokin VV German KE Sergeant C Simonoff M Robb F Slobodkin AI 《Applied microbiology and biotechnology》2007,76(2):467-472
Washed cell suspensions of the anaerobic hyperthermophilic archaea Thermococcus pacificus and Thermoproteus uzoniensis and the anaerobic thermophilic gram-positive bacteria Thermoterrabacterium ferrireducens and Tepidibacter thalassicus reduced technetium [99Tc(VII)], supplied as soluble pertechnetate with molecular hydrogen as an electron donor, forming highly insoluble Tc(IV)-containing
grayish-black precipitate. Apart from molecular hydrogen, T. ferrireducens reduced Tc(VII) with lactate, glycerol, and yeast extract as electron donors, and T. thalassicus reduced it with peptone. Scanning electron microscopy and X-ray microanalysis of cell suspensions of T. ferrireducens showed the presence of Tc-containing particles attached to the surfaces of non-lysed cells. This is the first report on the
reduction in Tc(VII) by thermophilic microorganisms of the domain Bacteria and by archaea of the phylum Euryarchaeota. 相似文献
103.
Traditional cultivation-based methods to quantify microbial abundance are not suitable for analyses of microbial communities
in environmental or medical samples, which consist mainly of uncultured microorganisms. Recently, different cultivation-independent
quantification approaches have been developed to overcome this problem. Some of these techniques use specific fluorescence
markers, for example ribosomal ribonucleic acid targeted oligonucleotide probes, to label the respective target organisms.
Subsequently, the detected cells are visualized by fluorescence microscopy and are quantified by direct visual cell counting
or by digital image analysis. This article provides an overview of these methods and some of their applications with emphasis
on (semi-)automated image analysis solutions. 相似文献
104.
Based on universal thermodynamic principles (Schwarz in Biophys Chem 86:119–129, 2000) it is shown how measured enthalpy changes can be utilized to determine the relevant binding isotherm as well as the variation
of the molar enthalpy change. This is carried out in a novel way involving multiple titration experiments whose evaluation
requires no beforehand assumptions or models whatever. An appropriate specific model mechanism may be discussed afterwards
and developed in view of the given experimental results. The pertinent procedure is demonstrated using micro-calorimetric
data obtained in the case of the local anesthetic dibucaine as it associates with POPC liposomes. Mutual interactions of the
bound ligand molecules could be described in terms of repulsive enthalpic and entropic activity coefficients. Apparently these
are induced by electrostatic forces and by the finite size of binding sites, respectively. 相似文献
105.
Hayashi A Aoyagi H Kinjyo K Yoshimura T Tanaka H 《Applied microbiology and biotechnology》2007,75(6):1437-1446
Screening method of microorganisms that utilized the symbiotic association between insect (Nasutitermes takasagoensis: Nt) and intestinal microorganisms was developed. The existence of desired microorganisms that grew by degrading difficult-to-degrade
materials in the gut was detected using survivability of Nt as an indicator. The desired microorganisms were isolated from
the survived Nt. It was thought that guts of Nt behave as continuous culture systems whereby microorganisms that cannot degrade
diet components are washed out, whereas those that can degrade it are retained and concentrated in the gut. About 60% of Nt
fed with phenol artificial diet (PAD) died within 7 days, while 4% of termites survived for 9 days. The structure of intestinal
microorganisms of the survived Nt fed with PAD differed from the bacterial communities obtained from enrichment culture (which
contained phenol) of wood-feeding Nt. Relatively high colonies (650-times) were detected in the gut of Nt fed on phenol artificial
diet compared with those obtained when Nt was fed on wood. Seven denaturing gradient gel electrophoresis (DGGE) bands were
detected from gut of wood-feeding Nt, whereas 11 DGGE-bands were detected from that of phenol-feeding Nt. Out of 11 DGGE-bands,
5 of them were sequenced, and bacterial species including phenol-degrading bacteria were identified. 相似文献
106.
Guliy OI Matora LY Burygin GL Dykman LA Ostudin NA Bunin VD Ignatov VV Ignatov OV 《Analytical biochemistry》2007,370(2):201-205
This work was undertaken to examine the electrooptical characteristics of cells of Azospirillum brasilense Sp245 during their interaction with antibodies developed to various cell surface epitopes. We used the dependences of the cell suspension optical density changes induced by electroorientation on the orienting field frequency (740, 1000, 1450, 2000, and 2800kHz). Cell interactions with homologous strain-specific antibodies to the A. brasilense Sp245 O antigen and with homologous antibodies to whole bacterial cells brought about considerable changes in the electrooptical properties of the bacterial suspension. When genus-specific antibodies to the flagellin of the Azospirillum sheathed flagellum and antibodies to the serologically distinct O antigen of A. brasilense Sp7 were included in the A. brasilense Sp245 suspension, the changes caused in the electrooptical signal were slight and had values close to those for the above changes. These findings agree well with the immunochemical characteristics of the Azospirillum O antigens and with the data on the topographical distribution of the Azospirillum major cell surface antigens. The obtained results can serve as a basis for the development of a rapid test for the intraspecies detection of microorganisms. 相似文献
107.
108.
We investigated the species identity of mat-forming ectomycorrhizal (EM) fungi associated with old- and second-growth Douglas-fir stands. Using molecular analyses of rhizomorphs and EM root tips, we characterized 28 unique internal transcribed spacer sequences and considered them proxies for mat-forming EM species. In both stand age classes, one Athelioid species in the genus Piloderma dominated our sample of the mat-forming fungal community. In second-growth stands, the second most frequently encountered mat-forming EM species belonged to the genus Hysterangium. In old-growth stands, several Ramaria species were associated with a frequently encountered mat morphology but no species dominated the community. After using rarefaction analysis to standardize sampling effort, the total species richness did not differ statistically between old- and second-growth habitats. Both an abundance of infrequently encountered species and incomplete sampling of the mat-forming EM community may have limited our ability to detect potential differences in species richness. Several frequently encountered Piloderma species appear to have broad (holarctic) distributions and diverse host associations and their potential importance in forest ecosystems warrants further study. 相似文献
109.
Paula Rodríguez María Barton Virginia Aldabalde Silvia Onetto Paola Panizza Pilar Menndez David Gonzalez Sonia Rodríguez 《Journal of Molecular Catalysis .B, Enzymatic》2007,49(1-4):8-11
Four strains of endophytic microorganisms isolated from carrot root were able to carry out the reduction of the carbonyl group with diverse degree of enantio-, and diasteroselectivity. Furthermore, biotransformation in the presence of bacterial inhibitor affects the stereochemical outcome of the reaction, and the concomitant addition of a yeast inhibitor results in a large decrease in the conversion percentage. These results indicate that endophytic microorganisms might be involved in the enantioselective reduction of ketones and ketoesters with fresh carrot root pieces. 相似文献
110.
Phytoremediation of polycyclic aromatic hydrocarbons in soil: part I. Dissipation of target contaminants 总被引:1,自引:0,他引:1
Phytoremediation has been demonstrated to be a viable cleanup alternative for soils contaminated with petroleum products. This study evaluated the application of phytoremediation to soil from a manufactured gas plant (MGP) site with high concentrations of recalcitrant, polycyclic aromatic hydrocarbons (PAHs). Two greenhouse studies investigated the potential dissipation and plant translocation of PAHs by fescue (Festuca arundinacea) and switchgrass (Panicum virgatum) in the first experiment and zucchini (Curcubita pepo Raven) in the second. The MGP soil was highly hydrophobic and initially inhibited plant growth. Two unplanted controls were established with and without fertilization. In the first experiment, concentrations of PAHs decreased significantly in all treatments after 12 mo. Plant biomass and microbial numbers were statistically equivalent among plant species. PAH concentrations in plant biomass were negligible for fescue and switchgrass. In the second experiment, zucchini enhanced the dissipation of several PAHs after 90 d of treatment when compared to the unvegetated soil. Plant tissue concentrations of PAHs were not elevated in the zucchini roots and shoots, and PAHs were not detectable in the fruit. 相似文献