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951.
High performance liquid chromatography followed by post-column reaction detection in the far-red spectral region provides added sensitivity and selectivity. A homogeneous fluorescence energy transfer assay in the competitive mode based on the binding of biotin and streptavidin was developed as an on-line post-column reaction detection system. The labels used for energy transfer were R-Phycoerythrin conjugated to biotin and Cyanine 5 labeled with streptavidin. The energy transfer peak was measured at 670 nm and excitation was achieved using the 488 nm line of an argon ion laser. The biotin concentration in plasma ultrafiltrate ranged from 0.024 to 6.12 ng/mL (n = 6). The precision of the two controls, 0.24 and 2. 44 ng/mL, was found to be 18.70% and 9.92% relative standard deviation respectively. Accuracy was 10.47% and 1.95% difference from spiked, respectively (n = 6). The limit of detection was 21.70 pg/mL (8.90 x 10(-11)M) calculated based on a factor of 2x the standard deviation of the blank (n = 6). The correlation coefficient for the calibration curve was found to be 0.9995. Recovery from plasma ultrafiltrate at 2.44 ng/mL was 103.40% (n = 6). Detection selectivity was indicated by the absence of background fluorescence in six different plasma samples collected from six individual donors. Endogenous levels were detected in two of the six pools of plasma ultrafiltrates. 相似文献
952.
A simple and reliable method was developed for analysis of 18 volatile organohalogen compounds (VOHCs) both indoors and outdoors, consisting of VOHC collection by a passive sampler, extraction with toluene by mechanical shaking, and automatic separation analysis by capillary gas-chromatography with electron capture detector (GC/ECD). The passive sampler is a porous polytetrafluoroethylene (PTFE) tube (30.30+/-0.37 mm net collection length, 5.0 mm inside diameter, 0.990 g weight) uniformly packed with activated charcoal (194.4+/-3.8 mg). The procedure was applied to a field survey on indoor and outdoor VOHC pollution in Shizuoka, Japan. Ten VOHCs, including trichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride, and p-dichlorobenzene, were detected from indoor and outdoor air samples. The ratios of maximum to minimum VOHC concentrations, both outdoors and indoors, were large. The indoor and outdoor concentrations of 1,1-dichloroethylene, dichloromethane, 1,1,1-trichloroethylene, carbon tetrachloride and trichloroethylene were found to be similar. Indoor concentrations of trihalomethanes, p-dichlorobenzene and tetrachloroethylene were higher than those of outdoors. 相似文献
953.
W. Jeitschko D.J. Braun R.H. Ashcraft R. Marchand 《Journal of solid state chemistry》1978,25(4):309-313
Twenty-six ternary phosphides Ln2T12P7 (Ln = lanthanoid, T = Fe, Co, Ni) were prepared for the first time by reaction of the elemental components in liquid tin or by reaction of the components in evacuated silica tubes. The analysis of their powder patterns indicates their isotypism with Zr2Fe12P7. Their lattice constants are reported. Gd2Ni12As7 also crystallizes with that structure. 相似文献
954.
The dansylated derivatives of ammonia, 1.3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, spermidine, histamine, and spermine were separated by one ascending development in chloroform—triethylamine (5:1) on a 250-μm silica gel 60 plate. Putrescine, cadaverine, spermidine, and spermine in human urine were quantitated by a direct scan of the fluorescent intensity of the spots corresponding to these compounds. Higher amounts of spermidine and spermine were found in the urines of cancer patients compared to the values of these substances in normal urine. 相似文献
955.
W E May S N Chesler S P Cram B H Gump H S Hertz D P Enagonio S M Dyszel 《Journal of chromatographic science》1975,13(11):535-540
The low concentration of hydrocarbons anticipated in pollution baseline studies necessitates the development of analytical techniques sensitive at the sub-microgram per kilogram concentration level. The method of analysis developed in this laboratory involves dynamic headspace sampling for volatile hydrocarbon components of the sample, followed by coupled-column liquid chromatography for the non-volatile components. These techniques require minimal sample handling, reducing the risk of sample component loss and/or sample contamination. Volatile sample components are separated from the matrix in a closed system and concentrated on a TENAX-GC packed pre-column, free from large amounts of solvent and ready for GC/GC-MS analysis. Non-volatile compounds, such as the benzpyrenes, may be extracted from large volumes of water and concentrated on a Bondapak C18 packed pre-column for coupled-column liquid chromatographic separation and analysis. Results of the application of these techniques to the analysis of samples from sites of known low level hydrocarbon contamination are presented and discussed. 相似文献
956.
H. D. Hollis Showalter John M. Domagala Joseph P. Sanchez 《Journal of heterocyclic chemistry》1981,18(8):1609-1612
Starting from readily available 1,2-dihydro-6-methyl-2-oxo-3-pyridinecarbonitrile, 1, viable synthetic pathways to a number of C-6 functionalized 1,2-dihydro-2-oxo-3-pyridinecarbonitriles and corresponding acids are presented. Through the utilization of dianion chemistry, the C-6 methyl substituent is selectively functionalized to three different oxidation levels. 相似文献
957.
Raman spectra of glassy aqueous LiX and CaX2 solutions (X = Cl,Br and I) in the low frequency region
Raman spectra of glassy aqueous LiX and CaX2 solutions are obtained in the low frequency region (10–900 cm?1). Two low frequency Raman bands are clearly observed. A qualitative discussion is given for the intensity correlation and observed frequency shifts of these bands with halide ions. 相似文献
958.
R. Pepelnik H. -U. Fanger W. Michaelis B. Anders 《Journal of Radioanalytical and Nuclear Chemistry》1982,72(1-2):393-403
A new intense 14 MeV neutron generator with cylindrical acceleration structure has been put in operation at the GKSS Research
Center Geesthacht. The sealed neutron tube is combined with a fast pneumatic rabbit system with particular capabilities for
neutron activation analysis involving shortlived reaction products. The sample transfer time is less than 140 ms. The maximum
neutron flux available for activation is 5.2·1010 n/cm2s. Theoretical sensitivity predictions made in a previous study have been verified for some important trace elements. As a
first application, samples of freeze-dried suspended matter and fishes of the Elbe river were analyzed. 相似文献
959.
Preparation, Thermal Stability, and Crystal Structure of the Calcium Arsenide Chloride Ca3AsCl3 CaAsCa3AsCl3 was prepared as a grayish white, microcrystalline powder by the reaction of Ca, As, and CaCl2 in the molar ratio 3:2:3 and by the reaction of “Ca3As2” and CaCl2 in the molar ratio 1:3. Colourless single crystals of the compound were obtained. Ca3AsCl3 begins to decompose reversibly at 1 025°C by forming the phase Ca2? xAs1? xCl1+x with x = 0.13 and CaCl2. Single crystal investigations show that Ca3AsCl3 is isotypic with Mg3NF3; see: “Inhaltsübersicht”. 相似文献
960.