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Jamin Huang Dean F. Bushey Michael D. Graves Brenda F. Johnson Dianne D. Singleton 《Journal of heterocyclic chemistry》1987,24(1):1-7
A series of 3-substituted-5-methoxy-1,3,4-oxadiazol-2-ones were prepared from aldehydes, ketones, phenylacetic acids, and 1,2- and 1,3-diketones. Conditions for the formation of these oxadiazolones from the precursor N-carbamoyl chlorides depended on the structure, and varied from spontaneous ring closure to those requiring bases. Variation in the N-3 substituents sometimes produced mixtures of isomers which were separated and identified. These molecules were prepared in order to study the effect of the N-3 substituent variation on the biological properties of oxadiazolones. 相似文献
4.
Janusz Z. Beer Kathleen M. Olvey Sharon A. Miller Delma P. Thomas Dianne E. Godar 《Photochemistry and photobiology》1993,58(5):676-681
The potential to induce non-nuclear changes in mammalian cells has been examined for (1) UVA1 radiation (340–400 nm, UVASUN 2000 lamp), (2) UVA + UVB (peak at 313 nm) radiation (FS20 lamp), and (3) UVC (254 nm) radiation (GI5T8 lamp). The effects of irradiation were monitored in vitro using three strains of L5178Y (LY) mouse lymphoma cells that markedly differ in sensitivity to UV radiation. Comparisons were made for the effects of approximately equitoxic fluences that reduced cell survival to 1–15%. Depending on the cell strain, the fluences ranged from 830 to 1600 kJ/m2 for the UVASUN lamp, 75 to 390 J/m2 for the FS20 lamp and 3.8 to 17.2 J/m2 for the G15T8 lamp. At the exposure level used in this study, irradiation with the UVASUN, but not the FS20 or G15T8, lamp induced a variety of non-nuclear changes including damage to cytoplasmic organelles and increased plasma membrane permeability and cell lysis. Cell lysis and membrane permeabilization were induced by the UVA1 emission of the UVASUN lamp, but not by its visible + IR components (>400 nm). The results show that the plasma membrane and other organelles of LY cells are highly sensitive to UVA1 but not to UVB or UVC radiation. Also UVA1, but not UVB or UVC radiation, causes rapid and extensive lysis of LY cells. In conclusion, non-nuclear damage contributes substantially to UVA cytotoxicity in all three strains of LY cells. 相似文献
5.
Cassandra L. Smith Jennifer L. Stauber Mark R. Wilson Dianne F. Jolley 《Analytical and bioanalytical chemistry》2014,406(1):305-315
Toxicity of metals to aquatic organisms is dependent on both external factors, such as exposure concentration and water quality parameters, and intracellular processes including specific metal-binding sites and detoxification. Current models used to predict copper toxicity in microalgae do not adequately consider these intracellular processes. This study compared the copper-binding proteins from four species of marine microalgae, Dunaliella tertiolecta, Tetraselmis sp., Phaedactylum tricornutum and Ceratoneis closterium, in controls (no added copper) and following a 72-h exposure to copper (sufficient to inhibit growth by approximately 50 %). Cells were lysed by sonication, which was optimised to obtain 54–94 % cell rupture for the different algae. Cell lysates were processed by immobilised metal affinity chromatography (IMAC) using Cu2+ as the bound metal (i.e. Cu-IMAC). Bound proteins were subsequently analysed by SDS-PAGE, comparing proteins recovered from algae that were exposed to copper versus untreated control cells. Individual proteins for which copper exposure resulted in changes to proteins present were excised from gels and further analysed by nano LC ESI-MS/MS; proteins were identified using the Mascot database. Proteins identified in this way included heat-shock proteins, rubisco, α- and β-tubulins and ATP synthase (β subunit). The results established that Cu-IMAC is a useful approach to identify proteins involved in copper binding in algae. This study identified several proteins that may play an active role in responses to copper toxicity in marine microalgae. Figure
Diagram representing the sample preparation steps from algal growth and copper exposure through to mass spectrometry (MS) analysis 相似文献
6.
Dianne?LangfordEmail author Rosemary?Hurford Makoto?Hashimoto Murat?Digicaylioglu Eliezer?Masliah 《BMC neuroscience》2005,6(1):8
Background
The blood brain barrier (BBB) is the first line of defence of the central nervous system (CNS) against circulating pathogens, such as HIV. The cytotoxic HIV protein, gp120, damages endothelial cells of the BBB, thereby compromising its integrity, which may lead to migration of HIV-infected cells into the brain. Fibroblast growth factor 2 (FGF2), produced primarily by astrocytes, promotes endothelial cell fitness and angiogenesis. We hypothesized that treatment of human umbilical vein endothelial cells (HUVEC) with FGF2 would protect the cells from gp120-mediated toxicity via endothelial cell survival signalling. 相似文献7.
John R. Kucklick Michele M. Schantz Rebecca S. Pugh Barbara J. Porter Dianne L. Poster Paul R. Becker Teri K. Rowles Stefan Leigh Stephen A. Wise 《Analytical and bioanalytical chemistry》2010,397(2):423-432
The National Institute of Standards and Technology (NIST) has a diverse collection of control materials derived from marine
mammal blubber, fat, and serum. Standard Reference Material (SRM) 1945 Organics in Whale Blubber was recertified for polychlorinated
biphenyl (PCB) congeners, organochlorine pesticides, and polybrominated diphenyl ether (PBDE) congeners. SRM 1945 has also
been assigned mass fraction values for compounds not frequently determined in marine samples including toxaphene congeners,
coplanar PCBs, and methoxylated PBDE congeners which are natural products. NIST also has assigned mass fraction values, as
a result of interlaboratory comparison exercises, for PCB congeners, organochlorine pesticides, PBDE congeners, and fatty
acids in six homogenate materials produced from marine mammal blubber or serum. The materials are available from NIST upon
request; however, the supply is very limited for some of the materials. The materials include those obtained from pilot whale
blubber (Homogenates III and IV), Blainville’s beaked whale blubber (Homogenate VII), polar bear fat (Homogenate VI), and
California sea lion serum (Marine Mammal Control Material-1 Serum) and blubber (Homogenate V). 相似文献
8.
Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants 总被引:3,自引:0,他引:3
Wise SA Poster DL Schantz MM Kucklick JR Sander LC Lopez de Alda M Schubert P Parris RM Porter BJ 《Analytical and bioanalytical chemistry》2004,378(5):1251-1264
Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
9.
In this work we devise efficient algorithms for finding the search directions for interior point methods applied to linear programming problems. There are two innovations. The first is the use of updating of preconditioners computed for previous barrier parameters. The second is an adaptive automated procedure for determining whether to use a direct or iterative solver, whether to reinitialize or update the preconditioner, and how many updates to apply. These decisions are based on predictions of the cost of using the different solvers to determine the next search direction, given costs in determining earlier directions. We summarize earlier results using a modified version of the OB1-R code of Lustig, Marsten, and Shanno, and we present results from a predictor–corrector code PCx modified to use adaptive iteration. If a direct method is appropriate for the problem, then our procedure chooses it, but when an iterative procedure is helpful, substantial gains in efficiency can be obtained. 相似文献
10.
Analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples: a critical review of gas chromatographic (GC) methods 总被引:1,自引:0,他引:1
Polycyclic aromatic hydrocarbons (PAHs) are frequently measured in the atmosphere for air quality assessment, in biological
tissues for health-effects monitoring, in sediments and mollusks for environmental monitoring, and in foodstuffs for safety
reasons. In contemporary analysis of these complex matrices, gas chromatography (GC), rather than liquid chromatography (LC),
is often the preferred approach for separation, identification, and quantification of PAHs, largely because GC generally affords
greater selectivity, resolution, and sensitivity than LC. This article reviews modern-day GC and state-of-the-art GC techniques
used for the determination of PAHs in environmental samples. Standard test methods are discussed. GC separations of PAHs on
a variety of capillary columns are examined, and the properties and uses of selected mass spectrometric (MS) techniques are
presented. PAH literature on GC with MS techniques, including chemical ionization, ion-trap MS, time-of-flight MS (TOF-MS),
and isotope-ratio mass spectrometry (IRMS), is reviewed. Enhancements to GC, for example large-volume injection, thermal desorption,
fast GC, and coupling of GC to LC, are also discussed with regard to the determination of PAHs in an effort to demonstrate
the vigor and robustness GC continues to achieve in the analytical sciences. 相似文献