全文获取类型
收费全文 | 685篇 |
免费 | 44篇 |
国内免费 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 10篇 |
2019年 | 24篇 |
2018年 | 18篇 |
2017年 | 19篇 |
2016年 | 28篇 |
2015年 | 42篇 |
2014年 | 44篇 |
2013年 | 37篇 |
2012年 | 67篇 |
2011年 | 72篇 |
2010年 | 32篇 |
2009年 | 39篇 |
2008年 | 46篇 |
2007年 | 33篇 |
2006年 | 33篇 |
2005年 | 31篇 |
2004年 | 19篇 |
2003年 | 20篇 |
2002年 | 24篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有730条查询结果,搜索用时 15 毫秒
51.
Novel fluorescent polyacrylonitrile nanoparticles were synthesized by microemulsion polymerization and Schiff base modification. By further modification with europium, the polyacrylonitrile nanoparticles could be used as a highly sensitive and rapid sensor for Bacillus anthracis spore detection in aqueous solution. The europium-modified polyacrylonitrile nanoparticles were readily combined with dipicolinic acid as a unique biomarker of B. anthracis, leading to high fluorescence emission. These nanoparticles enabled ratiometric detection without instrument-specific calibration due to the internal fluorescence reference. Additionally, the europium-modified polyacrylonitrile nanoparticle sensors exhibited a remarkable limit of detection (10pM) for dipicolinic acid and outstanding selectivity (160×) over aromatic ligands in aqueous solution. The ultrafine nanoparticle sensor showed a high capability for detecting anthrax due to the increased surface area-to-volume ratio and enhanced dispersibility. 相似文献
52.
Yoo KS Ahn JE Han JS Seo E Otgonbayar GE Han NS 《Journal of microbiology and biotechnology》2011,21(12):1243-1249
This study was performed to examine the use of NaOCl as an alternative antimicrobial compound in winemaking because of the potential health problems that may arise as a result of the use of SO2. For this, the blank (non-treated), control (SO2-added), and sample (NaOCl-treated) wines were made, and microbial and chemical changes including sensory characteristics were analyzed during the fermentation periods. Treatment of grapes with NaOCl decreased the initial contaminating microbial population in grape must, resulting in higher growth of yeast and lactic acid bacteria. After 200 days of fermentation, the chemical analysis of sample wine revealed that it had higher ethanol content, redness (a*), and concentrations of fruity ester compounds and lower total acidity than the control. In the sensory analyses, the sample wine obtained a higher overall acceptability score (5.70) than the control (4.26). This result reveals that NaOCl can be used as an alternative to SO2 in winemaking for inhibiting the growth of contaminating microorganisms. 相似文献
53.
Shim YH Kim YC Lee HJ Bougard F Dubois P Choi KC Chung CW Kang DH Jeong YI 《Journal of microbiology and biotechnology》2011,21(1):28-36
Diblock copolymers composed of poly(epsilon-caprolactone) (PCL) and poly(N,N-dimethylamino-2-ethyl methacrylate) (PDMAEMA), or methoxy polyethylene glycol(PEG), were synthesized via a combination of ring-opening polymerization and atom-transfer radical polymerization in order to prepare polymeric nanoparticles as an antifungal drug carrier. Amphotericin B (AmB), a natural antibiotic, was incorporated into the polymeric nanoparticles. The physical properties of AmB-incorporated polymeric nanoparticles with PCL-b-PDMAEMA and PCL-b-PEG were studied in relation to morphology and particle size. In the aggregation state study, AmB-incorporated PCL-b- PDMAEMA nanoparticles exhibited a monomeric state pattern of free AmB, whereas AmB-incorporated PCL-b- PEG nanoparticles displayed an aggregated pattern. In in vitro hemolysis tests with human red blood cells, AmBincorporated PCL-b-PDMAEMA nanoparticles were seen to be 10 times less cytotoxic than free AmB (5 microgram/ml). In addition, an improved antifungal activity of AmBincorporated polymeric nanoparticles was observed through antifungal activity tests using Candida albicans, whereas polymeric nanoparticles themselves were seen not to affect activity. Finally, in vitro AmB release studies were conducted, proving the potential of AmB-incorporated PCL-b-PDMAEMA nanoparticles as a new formulation candidate for AmB. 相似文献
54.
55.
Mi Seon Park Hyun Suk Shin Gyung-Suk Kil Jehee Lee Cheol Young Choi 《Ichthyological Research》2011,58(3):195-201
We examined changes in the expression of Na+/K+-ATPase mRNA in the gills of the cinnamon clownfish using quantitative real-time PCR in an osmotically changing environment
[seawater (35 psu; practical salinity unit, 1 psu ≈ 1‰) → brackish water (17.5 psu) and brackish water with prolactin]. The
expression of Na+/K+-ATPase mRNA in gills was increased after the transfer to brackish water, and the expression was repressed by prolactin treatment.
Also, activities of gill Na+/K+-ATPase and plasma cortisol levels increased after the transfer to brackish water and were repressed in brackish water with
prolactin treatment. Na+/K+-ATPase-immunoreactive cells were almost consistently observed in the gill filaments, but absent from the lamella epithelia.
The plasma osmolality level decreased in brackish water, but the level of this parameter increased in brackish water with
prolactin treatment during salinity change. These results suggest that the Na+/K+-ATPase gene plays an important role in osmoregulation in gills, and prolactin improves the hyperosmoregulatory ability of
cinnamon clownfish in a brackish water (hypoosmotic) environment. 相似文献
56.
Kang NS Jeong HJ Yoo YD Yoon EY Lee KH Lee K Kim G 《The Journal of eukaryotic microbiology》2011,58(2):152-170
Woloszynskia species are dinoflagellates in the order Suessiales inhabiting marine or freshwater environments; their ecophysiology has not been well investigated, in particular, their trophic modes have yet to be elucidated. Previous studies have reported that all Woloszynskia species are photosynthetic, although their mixotrophic abilities have not been explored. We isolated a dinoflagellate from coastal waters in western Korea and established clonal cultures of this dinoflagellate. On the basis of morphology and analyses of the small/large subunit rRNA gene (GenBank accession number=FR690459), we identified this dinoflagellate as Woloszynskia cincta. We further established that this dinoflagellate is a mixotrophic species. We found that W. cincta fed on algal prey using a peduncle. Among the diverse prey provided, W. cincta ingested those algal species that had equivalent spherical diameters (ESDs) ≤12.6 μm, exceptions being the diatom Skeletonema costatum and the dinoflagellate Prorocentrum minimum. However, W. cincta did not feed on larger algal species that had ESDs≥15 μm. The specific growth rates for W. cincta increased continuously with increasing mean prey concentration before saturating at a concentration of ca. 134 ng C/ml (1,340 cells/ml) when Heterosigma akashiwo was used as food. The maximum specific growth rate (i.e. mixotrophic growth) of W. cincta feeding on H. akashiwo was 0.499 d(-1) at 20 °C under illumination of 20 μE/m(2) /s on a 14:10 h light-dark cycle, whereas its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was 0.040 d(-1). The maximum ingestion and clearance rates of W. cincta feeding on H. akashiwo were 0.49 ng C/grazer/d (4.9 cells/grazer/d) and 1.9 μl/grazer/h, respectively. The calculated grazing coefficients for W. cincta on co-occurring H. akashiwo were up to 1.1 d(-1). The results of the present study suggest that grazing by W. cincta can have a potentially considerable impact on prey algal populations. 相似文献
57.
Farrar CT Kamoun WS Ley CD Kim YR Catana C Kwon SJ Rosen BR Jain RK Sorensen AG 《PloS one》2011,6(3):e17228
MRI biomarkers of tumor edema, vascular permeability, blood volume, and average vessel caliber are increasingly being employed to assess the efficacy of tumor therapies. However, the dependence of these biomarkers on a number of physiological factors can compromise their sensitivity and complicate the assessment of therapeutic efficacy. Here we examine the response of these MRI tumor biomarkers to cediranib, a potent vascular endothelial growth factor receptor (VEGFR) inhibitor, in an orthotopic mouse glioma model. A significant increase in the tumor volume and relative vessel caliber index (rVCI) and a slight decrease in the water apparent diffusion coefficient (ADC) were observed for both control and cediranib treated animals. This contrasts with a clinical study that observed a significant decrease in tumor rVCI, ADC and volume with cediranib therapy. While the lack of a difference between control and cediranib treated animals in these biomarker responses might suggest that cediranib has no therapeutic benefit, cediranib treated mice had a significantly increased survival. The increased survival benefit of cediranib treated animals is consistent with the significant decrease observed for cediranib treated animals in the relative cerebral blood volume (rCBV), relative microvascular blood volume (rMBV), transverse relaxation time (T2), blood vessel permeability (K(trans)), and extravascular-extracellular space (ν(e)). The differential response of pre-clinical and clinical tumors to cediranib therapy, along with the lack of a positive response for some biomarkers, indicates the importance of evaluating the whole spectrum of different tumor biomarkers to properly assess the therapeutic response and identify and interpret the therapy-induced changes in the tumor physiology. 相似文献
58.
Park SY Kim S Yoon H Kim KB Kalme SS Oh S Song CS Kim DE 《Nucleic acid therapeutics》2011,21(6):395-402
Avian influenza is an acute viral respiratory disease caused by RNA viruses of the family Orthomyxoviridae. The influenza A virus subtype H5 can cause severe illness and results in almost 100% mortality rate among livestock. Hemagglutinin (HA) present in the virus envelope plays an essential role in the initiation of viral infection. In this study, we investigated the efficacy of using HA as a target for antiviral therapy through nucleic acid aptamers. After purification of the receptor binding domain (HA1) of HA protein, activity of recombinant HA1 was confirmed by using hemagglutination assay. We selected RNA aptamer candidates after 15 rounds of iterative Systematic Evolution of Ligands by EXponential enrichment (SELEX) targeting the biologically active HA protein. The selected RNA aptamer HAS15-5, which specifically binds to HA1, exhibited significant antiviral efficacy according to the results of a hemagglutination inhibition assay using egg allantoic fluids harboring the virus. Thus, the RNA aptamer HAS15-5, which acts by blocking and inhibiting the receptor-binding domain of viral HA, can be developed as a novel antiviral agent against type H5 avian influenza virus. 相似文献
59.
Nam Hee Yoo Ok Tae Kim Jung Bong Kim Sun Hee Kim Young Chang Kim Kyong Hwan Bang Dong Yun Hyun Seon Woo Cha Min Young Kim Baik Hwang 《Plant biotechnology reports》2011,5(3):283-287
In order to produce centellosides from whole plant cultures of Centella asiatica (L.) Urban, we evaluated the synergistic effects of thidiazuron (TDZ) and methyl jasmonate (MJ) on whole plant growth and
centelloside production. After 4 weeks of treatment with 0.025 mg/L of TDZ coupled with 0.1 mM MJ, the production of madecassoside
and asiaticoside from whole plant cultures was estimated to be 2.40- and 2.44-fold, respectively, above that of MJ elicitation
alone. When whole plants were treated with a growth regulator and an elicitor, the growth of whole plants, as compared to
the controls, did not differ. Additionally, total phytosyterol content in the leaves of whole plants co-treated with MJ and
TDZ was 1.08-fold greater than those of MJ alone. These results demonstrate that combined treatments not only stimulate the
accumulation of centellosides in the leaves but also inhibit the reduction of phytosterol levels caused by MJ elicitation. 相似文献
60.
Nucleic acid-based aptamers offer many potential advantages relative to antibodies and other protein-based affinity reagents, including facile chemical synthesis, reversible folding, improved thermal stability and lower cost. However, their selection requires significant time and resources and selections often fail to yield molecules with affinities sufficient for molecular diagnostics or therapeutics. Toward a selection technique that can efficiently and reproducibly generate high performance aptamers, we have developed a microfluidic selection process (M-SELEX) that can be used to obtain high affinity aptamers against diverse protein targets. Here, we isolated DNA aptamers against three protein targets with different isoelectric points (pI) using a common protocol. After only three rounds of selection, we discovered novel aptamer sequences that bind to platelet derived growth factor B (PDGF-BB; pI = 9.3) and thrombin (pI = 8.3) with respective dissociation constants (Kd) of 0.028 nM and 0.33 nM, which are both superior to previously reported aptamers against these targets. In parallel, we discovered a new aptamer that binds to apolipoprotein E3 (ApoE; pI = 5.3) with a Kd of 3.1 nM. Furthermore, we observe that the net protein charge may exert influence on the affinity of the selected aptamers. To further explore this relationship, we performed selections against PDGF-BB under different pH conditions using the same selection protocol, and report an inverse correlation between protein charge and aptamer Kd. 相似文献