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991.
We introduce a novel computational approach to predict effective genome size (EGS; a measure that includes multiple plasmid copies, inserted sequences, and associated phages and viruses) from short sequencing reads of environmental genomics (or metagenomics) projects. We observe considerable EGS differences between environments and link this with ecologic complexity as well as species composition (for instance, the presence of eukaryotes). For example, we estimate EGS in a complex, organism-dense farm soil sample at about 6.3 megabases (Mb) whereas that of the bacteria therein is only 4.7 Mb; for bacteria in a nutrient-poor, organism-sparse ocean surface water sample, EGS is as low as 1.6 Mb. The method also permits evaluation of completion status and assembly bias in single-genome sequencing projects. 相似文献
992.
Inventory and monitoring of wine microbial consortia 总被引:2,自引:0,他引:2
The evolution of the wine microbial ecosystem is generally restricted to Saccharomyces cerevisiae and Oenococcus oeni, which are the two main agents in the transformation of grape must into wine by acting during alcoholic and malolactic fermentation,
respectively. But others species like the yeast Brettanomyces bruxellensis and certain ropy strains of Pediococcus parvulus can spoil the wine. The aim of this study was to address the composition of the system more precisely, identifying other
components. The advantages of the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approach to
wine microbial ecology studies are illustrated by bacteria and yeast species identification and their monitoring at each stage
of wine production. After direct DNA extraction, PCR-DGGE was used to make the most exhaustive possible inventory of bacteria
and yeast species found in a wine environment. Phylogenetic neighbor-joining trees were built to illustrate microbial diversity.
PCR-DGGE was also combined with population enumeration in selective media to monitor microbial changes at all stages of production.
Moreover, enrichment media helped to detect the appearance of spoilage species. The genetic diversity of the wine microbial
community and its dynamics during winemaking were also described. Most importantly, our study provides a better understanding
of the complexity and diversity of the wine microbial consortium at all stages of the winemaking process: on grape berries,
in must during fermentation, and in wine during aging. On grapes, 52 different yeast species and 40 bacteria could be identified.
The diversity was dramatically reduced during winemaking then during aging. Yeast and lactic acid bacteria were also isolated
from very old vintages. B. bruxellensis and O. oeni were the most frequent. 相似文献
993.
Flocculation of microalgae using cationic starch 总被引:2,自引:0,他引:2
Dries Vandamme Imogen Foubert Boudewijn Meesschaert Koenraad Muylaert 《Journal of applied phycology》2010,22(4):525-530
Due to their small size and low concentration in the culture medium, cost-efficient harvesting of microalgae is a major challenge.
We evaluated the potential of cationic starch as a flocculant for harvesting microalgae using jar test experiments. Cationic
starch was an efficient flocculant for freshwater (Parachlorella, Scenedesmus) but not for marine microalgae (Phaeodactylum, Nannochloropsis). At high cationic starch doses, dispersion restabilization was observed. The required cationic starch dose to induce flocculation
increased linearly with the initial algal biomass concentration. Of the two commercial cationic starch flocculants tested,
Greenfloc 120 (used in wastewater treatment) was more efficient than Cargill C*Bond HR 35.849 (used in paper manufacturing).
For flocculation of Parachlorella using Greenfloc 120, the cationic starch to algal biomass ratio required to flocculate 80% of algal biomass was 0.1. For
Scenedesmus, a lower dose was required (ratio 0.03). Flocculation of Parachlorella using Greenfloc 120 was independent of pH in the pH range of 5 to 10. Measurements of the maximum quantum yield of PSII suggest
that Greenfloc 120 cationic starch was not toxic to Parachlorella. Cationic starch may be used as an efficient, nontoxic, cost-effective, and widely available flocculant for harvesting microalgal
biomass. 相似文献
994.
Se-Wook Jung Tae-Kwon Kim Kwang-Woo Lee Yong-Hyun Lee 《Biotechnology and Bioprocess Engineering》2007,12(3):207-212
The catalytic properties of β-cyclodextrin glucanotransferase (β-CGTase) from alkalophilicBacillus sp. BL-12 specific for the intermolecular transglycosylation of stevioside were investigated. The molecular mass of purified
β-CGTase by ultra-filtration and β-cyclodextrin polymer affinity chromatography was estimated to be 90 kDa, which is high
compared to other known bacterial CGTases. The optimal pH and temperature were 9.0 and 50°C, respectively, and thermal stability
at 40°C was elevated 10-fold in the presence of 1% maltodextrin. The kinetic parameters of the new β-CGTase from alkalophilicBacillus sp. BL-12 indicate that it is more suitable for transglycosylation than the cyclization reaction. Maltodextrin was the most
suitable glycosyl donor for transglycosylation of stevioside. The transglycosylation of stevioside was carried out using 60
units of CGTase per gram of maltodextrin, 20 g/L stevioside as the glycosyl acceptor, and 50 g/L maltodextrin as the gycosyl
donor at 40°C for 6 h, and a conversion yield of stevioside as high as 76% was obtained. 相似文献
995.
Aims
To clone, characterize and compare the bile salt hydrolase (BSH) genes of Lactobacillus johnsonii PF01.Methods and Results
The BSH genes were amplified by polymerase chain reaction (PCR) using specific oligonucleotide primers, and the products were inserted into the pET21b expression vector. Escherichia coli BLR (DE3) cells were transformed with pET21b vectors containing the BSH genes and induced using 0·1 mmol l?1 isopropylthiolgalactopyranoside. The overexpressed BSH enzymes were purified using a nickel–nitrilotriacetic acid (Ni2+‐NTA) agarose column and their activities characterized. BSH A hydrolysed tauro‐conjugated bile salts optimally at pH 5·0 and 55°C, whereas BSH C hydrolysed glyco‐conjugated bile salts optimally at pH 5·0 and 70°C. The enzymes had no preferential activities towards a specific cholyl moiety.Conclusions
BSH enzymes vary in their substrate specificities and characteristics to broaden its activity. Despite the lack of conservation in their putative substrate‐binding sites, these remain functional through motif conservation.Significance and Impact of the Study
This is to our knowledge the first report of isolation of BSH enzymes from a single strain, showing hydrolase activity towards either glyco‐conjugated or tauro‐conjugated bile salts. Future structural homology studies and site‐directed mutagenesis of sites associated with substrate specificity may elucidate specificities of BSH enzymes. 相似文献996.
997.
Li Sun Quan Yuan Tianhua Xu Li Yao Jiangmin Feng Jianfei Ma Lining Wang Changlong Lv Danan Wang 《Biotechnology letters》2017,39(8):1159-1166
Objectives
To investigate the potential of interleukin (IL)-15 as a novel adjuvant for Mycobacterium tuberculosis (Mtb) antigen 85A (Ag85A) vaccine.Results
C57BL/6 mice were intramuscularly immunized three times with a plasmid expressing the Ag85A-IL-15 fusion protein (pcDNA3.1-Ag85A-IL-15), with the empty pcDNA3.1 vector and the pcDNA3.1-Ag85A as control. Mice vaccinated with pcDNA3.1-Ag85A-IL-15 generated more secretory IgA (sIgA) into their lung (209 ± 21 μg/ml) and acquired an enhanced serum IgG response to Ag85A. IgG2a/IgG1 ratios were upregulated, natural killer cell activity was augmented and Ag85A-specific splenic T cell proliferation was enhanced in these mice as well. Vaccination with pcDNA3.1-Ag85A-IL-15 promoted the polarization of CD4+ T cells towards a Th1 type in the spleen, and significantly upregulated the serum level of interferon (IFN)-γ (458 ± 98 pg/ml), a typical Th1 cytokine. IFN-γ-expressing CD8+ cells were also increased in the spleen after pcDNA3.1-Ag85A-IL-15 immunization.Conclusions
A superior immune type I response in mice vaccinated with plasmid Ag85A-IL-15 has been achieved.998.
Zaprionus indianus is a recent invader in Brazil and was probably introduced from the West Afrotropical zone. So far, studies regarding its
chromosomal polymorphism were limited to India. We found that Brazilian populations were very different from Indian ones.
Five new inversions have been discovered. In(II)A, already described in India, where it is quite common, has also been found in Brazil, where it is very rare. The X-chromosome
has three inversions; In(X)Na, In(X)Ke and In(X)Eg, which are frequent in all Brazilian populations studied. In every case, we observed strong linkage disequilibrium among
these gene arrangements. During the primary collection period (2001–2002), we noticed a significant positive correlation between
the frequency of these inversions and latitude, but this was not confirmed in later investigations. Rearrangement In(IV)EF was also common in all populations, while inversion In(V)B was only found in southern populations. Our data suggest that the founders that recently invaded Brazil were polymorphic
for the six inversions observed. The place of origin might be identified more precisely by investigating West African populations.
In order to facilitate further investigations, we present an updated polytene chromosome photomap, locating the breakpoints
of every inversion observed in Brazilian populations.
Galina Ananina and Cláudia Rohde contributed equally to this work 相似文献
999.
Seo M Lee MJ Heo JH Lee YI Kim Y Kim SY Lee ES Juhnn YS 《The Journal of biological chemistry》2007,282(34):24720-24730
UV radiation induces various cellular responses by regulating the activity of many UV-responsive enzymes, including MAPKs. The betagamma subunit of the heterotrimeric GTP-binding protein (Gbetagamma) was found to mediate UV-induced p38 activation via epidermal growth factor receptor (EGFR). However, it is not known how Gbetagamma mediates the UVB-induced activation of EGFR, and thus we undertook this study to elucidate the mechanism. Treatment of HaCaT-immortalized human keratinocytes with conditioned medium obtained from UVB-irradiated cells induced the phosphorylations of EGFR, p38, and ERK but not that of JNK. Blockade of heparin-binding EGF-like growth factor (HB-EGF) by neutralizing antibody or CRM197 toxin inhibited the UVB-induced activations of EGFR, p38, and ERK in normal human epidermal keratinocytes and in HaCaT cells. Treatment with HB-EGF also activated EGFR, p38, and ERK. UVB radiation stimulated the processing of pro-HB-EGF and increased the secretion of soluble HB-EGF in medium, which was quantified by immunoblotting and protein staining. In addition, treatment with CRM179 toxin blocked UV-induced apoptosis, but HB-EGF augmented this apoptosis. Moreover, UVB-induced apoptosis was reduced by inhibiting EGFR or p38. The overexpression of Gbeta(1)gamma(2) increased EGFR-activating activity and soluble HB-EGF content in conditioned medium, but the sequestration of Gbetagamma by the carboxyl terminus of G protein-coupled receptor kinase 2 (GRK2ct) produced the opposite effect. The activation of Src increased UVB-induced, Gbetagamma-mediated HB-EGF secretion, but the inhibition of Src blocked that. Overexpression of Gbetagamma increased UVB-induced apoptosis, and the overexpression of GRK2ct decreased this apoptosis. We conclude that Gbetagamma mediates UVB-induced human keratinocyte apoptosis by augmenting the ectodomain shedding of HB-EGF, which sequentially activates EGFR and p38. 相似文献
1000.
Il-Chan Kim Young Ja Kim Young-Mi Lee Bok-Geon Kim Tae-Jin Park Hyeung-Sin Kim Min-Min Jung Tim D Williams Wonchoel Lee Jae-Seong Lee 《DNA sequence》2004,15(2):159-163
We synthesized a cDNA library from the intertidal copepod Tigriopus japonicus, converted it to phagemids and sequenced expressed sequence tags (ESTs). Of these, Tigriopus translationally controlled tumor protein/histamine releasing factor (TCTP/HRF) was further characterized. The Tigriopus TCTP/HRF gene encoded 172 amino acid residues and showed high similarity to Drosophila but moderate similarity to other annelids (e.g. Brugia, Wuchereria and C. elegans). The Tigriopus TCTP/HRF gene appeared in the same clade as the annelids. Here, we describe the analysis of the Tigriopus TCTP/HRF gene. 相似文献