全文获取类型
收费全文 | 98篇 |
免费 | 0篇 |
专业分类
化学 | 71篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 14篇 |
出版年
2021年 | 5篇 |
2019年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 9篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有98条查询结果,搜索用时 15 毫秒
61.
Penelope J. Lundmark Gregory J. Kubas Ray J. Butcher 《Journal of chemical crystallography》1997,27(6):377-379
The structure of the title compound,syn-[Cp*MoO(μ?S)]2,1, has been determined.1 crystallized in the monoclinic space groupC2/c with dimensionsa=11.758(2),b=12.243(2), c = 15.585(3)Å, β=104.63(3)°. The reaction of Cp* 2Mo2(S2)(S)(S2O3) with Me2PhP producessyn-[Cp*MoO(μ?S)]2 and Me2PhPO. The compounds [Cp′MoO(μ?S)]2 [Cp′=Cp, CpMe, Cp*] can exist as either thesyn- oranti-isomers. The present structure,syn-[Cp*MoO(μ?S)]2 is compared with the structure of theanti-isomer and with the previously determined structure ofsyn-[Cp*MoO(μ?S)]2 in a different space group. 相似文献
62.
A microfabricated, inexpensive, reusable glass capillary electrophoresis chip and a laser-induced fluorescence system were developed in-house for the rapid DNA-based analysis of genetically modified organisms (GMOs). The 35S promoter sequence of cauliflower mosaic virus and the terminator of the nopaline synthase (NOS) gene from Agrobacterium tumefaciens were both detected since they are present in most genetically modified organisms. The detection of genetically modified soybean in the presence of unaltered soybean was chosen as a model. Lectin, a plant-specific gene, was also detected for confirmation of the integrity of extracted DNA. The chip was composed of two glass plates, each 25 x 76 mm, thermally bonded together to form a closed structure. Photomasks with cross-topology were prepared rapidly by using polymeric material instead of chrome plates. The widths of the injection and separation channels were 30 and 70 microm, respectively, the effective separation length 4.5 cm. The glass slide was etched to a depth of 30 microm for both the injection and separation channel. The cost of the chip was less than 1 $ and required 2 days for photomask preparation and microfabrication. The separation and detection of polymerase chain reaction-amplified NOS, 35S, and lectin sequences (180, 195, and 181 bp, respectively) was completed in less than 60 s. As low as 0.1% GMO content was detectable by the proposed system after 35 and 40 amplification cycles for 35S and NOS, respectively, using 25 ng of extracted DNA as starting material. This corresponds to only 20 genome copies of genetically modified soybean. 相似文献
63.
64.
Truman P Stirling DJ Northcote P Lake RJ Seamer C Hannah DJ 《Journal of AOAC International》2002,85(5):1057-1063
A neuroblastoma assay for determination of brevetoxins in shellfish was developed together with a method for sample cleanup that allows separation of brevetoxins from most of the components that cause matrix interference in the assay. This improved assay method was applied to a range of shellfish samples with different characteristics. Extracts of naturally contaminated and nontoxic shellfish together with extracts spiked with known amounts of toxin were tested. The results demonstrated that brevetoxins could be reliably detected in shellfish extracts at concentrations below the regulatory limit. Brevetoxin activity was detected in 15 of 23 samples from 5 separate toxicity incidents in which shellfish tested positive in the neurotoxic shellfish poisoning (NSP) mouse bioassay. Twelve of these positive NSP results came from 2 toxicity incidents. Yessotoxin was the major contributor to toxicity in 2 other incidents, although some samples contained both yessotoxin and brevetoxin. The sample from the remaining incident contained an unidentified toxin bioactivity, together with gymnodimine. In contrast to earlier versions of the neuroblastoma assay, gymnodimine was not detected by this modified method. 相似文献
65.
The recombinant photoprotein aequorin was used as a reporter in highly sensitive and automatable hybridization assays for the analysis of transgenic sequences in genetically modified organisms (GMO). The terminator of the nopaline synthase gene (NOS) from Agrobacterium tumefaciens and the 35S promoter sequence were detected in genetically modified soybean. The endogenous, soybean-specific, lectin gene was also detected for confirmation of the integrity of extracted DNA. A universal detection reagent was produced through conjugation of aequorin to the oligonucleotide (dA)30. Biotinylated (through PCR) products for the three target sequences were captured onto streptavidin-coated wells, and one strand was removed by NaOH treatment. The immobilized single-stranded DNAs were then hybridized with oligonucleotide probes consisting of a target-specific segment and a poly(dT) tail. This allowed the subsequent determination of all hybrids through the use of the (dA)30-aequorin conjugate as a universal reagent. The bound aequorin was measured by adding Ca2+ and integrating the light emission for 3 s. As low as 2 pM (100 amol per well) of amplified DNA was detectable for all three targets, with a signal-to-background ratio of about 2. The analytical range extended up to 2000 pM. As low as 0.05% GMO content in soybean can be detected with a signal-to-background ratio of 8.2. The overall repeatability of the proposed assay, including DNA extraction, PCR, and hybridization assay, ranged from 7.5–19.8%. The use of a (dA)30-aequorin conjugate renders the assay configuration general for any target DNA, provided that the specific probe carries a poly(dT) tail. 相似文献
66.
4-Mercapto-1,2-dithiole-3-thiones are easily prepared by deprotonation of terminal alkynes followed by sequential treatment with carbon disulfide, sulfur and acid; addition of alkylating agents at the last stage gives 4-alkylthio-1,2-dithiole-3-thiones instead. 相似文献
67.
Craig PR Brothers PJ Clark GR Wilson WR Denny WA Ware DC 《Dalton transactions (Cambridge, England : 2003)》2004,(4):611-618
Synthetic approaches to cobalt(III) complexes [Co(L)(L')2] containing the bidentate dialkylating nitrogen mustard N,N-bis(2-chloroethyl)-1,2-ethanediamine (L = dce) together with anionic ancilliary ligands (L') which are either carbonato (CO3(2-)), oxalato (ox2-), bis(2-hydroxyethyl)dithiocarbamato (bhedtc-), 2-pyridine carboxylato (pico-) or 2-pyrazine carboxylato (pyzc-) were investigated. Synthetic routes were developed using the related amines N,N-diethyl-1,2-ethanediamine (dee) and 1,2-ethanediamine (en). The complexes [Co(CO3)2(L)]- (L = dee 1, dce 2), [Co(ox)2(L)]- (L = dee 3, dce 4), [Co(bhedtc)2(dee)]+ 5, [Co(bhedtc)2(en)]+ 6, mer-[Co(pico)3], mer-[Co(pyzc)]3 7 and [Co(pico)2(dee)]+ 8 were prepared and were characterised by IR, UV-Vis, 1H and 13C[1H] NMR spectroscopy, mass spectrometry and cyclic voltammetry. [Co(bhedtc)2(en)]BPh4 6b and trans(O)-[Co(pico)2(dee)]ClO4 8 were characterised by X-ray crystallography. In vitro biological tests were carried out on complexes 1-4 in order to assess the degree to which coordination of the mustard to cobalt attenuated its cytotoxicity, and the differential toxicity in air vs. nitrogen. 相似文献
68.
69.
Advanced cervical cancer is primarily managed using cytotoxic therapies, despite evidence of limited efficacy and known toxicity. There is a current lack of alternative therapeutics to treat the disease more effectively. As such, there have been more research endeavors to develop targeted therapies directed at oncogenic host cellular targets over the past 4 decades, but thus far, only marginal gains in survival have been realized. The E6 oncoprotein, a protein of human papillomavirus origin that functionally inactivates various cellular antitumor proteins through protein–protein interactions (PPIs), represents an alternative target and intriguing opportunity to identify novel and potentially effective therapies to treat cervical cancer. Published research has reported a number of peptide and small-molecule modulators targeting the PPIs of E6 in various cell-based models. However, the reported compounds have rarely been well characterized in animal or human subjects. This indicates that while notable progress has been made in targeting E6, more extensive research is needed to accelerate the optimization of leads. In this review, we summarize the current knowledge and understanding of specific E6 PPI inhibition, the progress and challenges being faced, and potential approaches that can be utilized to identify novel and potent PPI inhibitors for cervical cancer treatment. 相似文献
70.
Advances in molecular techniques for the detection and quantification of genetically modified organisms 总被引:3,自引:1,他引:2
Elenis DS Kalogianni DP Glynou K Ioannou PC Christopoulos TK 《Analytical and bioanalytical chemistry》2008,392(3):347-354
Progress in genetic engineering has led to the introduction of genetically modified organisms (GMOs) whose genomes have been
altered by the integration of a novel sequence conferring a new trait. To allow consumers an informed choice, many countries
require food products to be labeled if the GMO content exceeds a certain threshold. Consequently, the development of analytical
methods for GMO screening and quantification is of great interest. Exponential amplification by the polymerase chain reaction
(PCR) remains a central step in molecular methods of GMO detection and quantification. In order to meet the challenge posed
by the continuously increasing number of GMOs, various multiplex assays have been developed for the simultaneous amplification
and/or detection of several GMOs. Classical agarose gel electrophoresis is being replaced by capillary electrophoresis (CE)
systems, including CE chips, for the rapid and automatable separation of amplified fragments. Microtiter well-based hybridization
assays allow high-throughput analysis of many samples in a single plate. Microarrays have been introduced in GMO screening
as a technique for the simultaneous multianalyte detection of amplified sequences. Various types of biosensors, including
surface plasmon resonance sensors, quartz crystal microbalance piezoelectric sensors, thin-film optical sensors, dry-reagent
dipstick-type sensors and electrochemical sensors were introduced in GMO screening because they offer simplicity and lower
cost. GMO quantification is performed by real-time PCR (rt-QPCR) and competitive PCR. New endogenous reference genes have
been validated. rt-QPCR is the most widely used approach. Multiplexing is another trend in this field. Strategies for high-throughput
multiplex competitive quantitative PCR have been reported. 相似文献