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991.
气相色谱质谱联用仪与微机的数据传输和处理 总被引:1,自引:0,他引:1
报道了一种用于气相色谱质谱联用仪和微机之间实现数据传输和处理的方法。方法可更有效地利用质谱仪采集的数据,解决了工作站处理数据的局限性。经数据格式转换,原始数据可以在微机上实现色谱峰再现,从而为色谱条件的优化和定量数据处理创造了条件。 相似文献
992.
Summary Chemiluminescent reactions of ozone with several classes of compounds at different temperatures are described. In a reaction chamber in front of a photomultiplier ozone is mixed with the compounds studied such as alkanes, olefins, alcohols, aromatics, C2H2, NO, vinyl chloride or H2S. The chemiluminescent emission is proportional to the concentration of the compound involved. At room temperature only olefinic hydrocarbons respond but at temperatures above 150°C also a response for alkanes, alcohols, CO etc. is obtained. It is suggested that next to the ozonide-excited formaldehyde mechanism the CO-CO
2
*
mechanism is responsible for the chemiluminescent emission at high temperature. A detection limit of a few ppb is achieved. Possible applications are a selective gas-chromatographic detector, an air pollution monitor for instance for CO, and a photochemical reactivity monitor.
Bestimmung reaktiver Kohlenwasserstoffe durch Chemiluminescenz
Zusammenfassung Chemiluminescenzreaktionen von Ozon mit verschiedenen Verbindungsgruppen (hauptsächlich Kohlenwasserstoffe) bei unterschiedlichen Temperaturen werden beschrieben. In einer Reaktionskammer werden die Verbindungen vor einem Photomultiplier mit Ozon vermischt. Es handelt sich u. a. um folgende Verbindungstypen: Alkane, Olefine, Alkohole, Aromaten, C2H2, NO, Vinylchlorid, H2S. Die Emissionsintensität ist proportional der Konzentration. Bei Raumtemperatur sprechen nur Olefine an, die übrigen Verbindungen erst über 150°C. Die Emission bei höherer Temperatur wird neben der Bildung von Formaldehyd auf die Reaktion CO-CO 2 * zurückgeführt. Die Nachweisgrenze beträgt wenige ppb. Als mögliche Anwendungsgebiete werden ein selektiver GC-Detektor, ein Monitor für Luftverunreinigungen (z.B. für CO) sowie ein Monitor zur Messung photochemischer Reaktivität der Luft genannt.
Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria. 相似文献
993.
乙酰化淀粉/DL-丙交酯接枝共聚物的合成及降解性能研究 总被引:7,自引:0,他引:7
用醋酸乙烯酯和玉米淀粉反应制备出了不同取代度乙酰化淀粉,再用乙酰化淀粉同DL-丙交酯接枝共聚合成乙酰化淀粉/DL-丙交酯接枝共聚物。研究了原料配比,淀粉取代度对接枝反应单体转化率(C%),接枝率(G%)接枝效率(GE%)和接枝支链数均分子量(Mn)的影响,结果表明在给定的试验条件下接枝共聚反应的C%,G%,GE%和Mn可分别达到40%,225%,80%和1.4万。接枝共聚物在磷酸缓冲溶液和户外土壤掩埋降解实验表明,在160天内样品失重率分别为71%和60%,表明合成的乙酰化淀粉/DL-丙交酯接枝共聚物具有很好的降解性能。 相似文献
994.
995.
J. C. Masini Oswaldo E. S. Godinho Luiz M. Aleixo 《Fresenius' Journal of Analytical Chemistry》1998,360(1):104-111
A linearization method based on modified Gran functions, and a general nonlinear regression program were used to study potentiometric
titration curves of denatured ovalbumin and lysozyme in 6 mol L–1 guanidine hydrochloride medium with the aim of determining the ionizable species. With both numerical techniques it was possible
to determine the sum of the carboxylic groups, the imidazol, the α-amine, and the sum of ɛ-amine, phenolic and sulfhydryl
groups, if the protein is completely denatured, and assumes a randomly coiled conformation. A total of 87.8 ± 2.5 and 20.7
± 0.6 groups per mol were determined in the ovalbumin and lysozyme, respectively. These values are very close to the 88 and
21 groups expected by aminoacid composition of both proteins, indicating that all ionizable groups were exposed to the solvent.
For ovalbumin the distribution of groups was very similar to that expected by the aminoacid composition, but for lysozyme
some anomalies were observed, suggesting the existence of interactions between ionizable groups, altering the dissociation
constants.
Received: 9 December 1996 / Revised: 27 February 1997 / Accepted: 4 March 1997 相似文献
996.
J. Nasielski S. Heilporn R. Nasielski-Hinkens
B. Tinant
J. P. Declercq 《Tetrahedron》1989,45(24):7795-7804When quinoxaline-N-oxide 1 is reacted with KCN and benzoyl chloride in water (the Reissert reaction) or methanol, the products are 2-,5- and 6- chloroquinoxaline (the latter being the major product: 42±6 %) and small amounts of 2-cyanoquinoxaline. Using three equivalents of trimethylsilyl cyanide instead of KCN, and dichloromethane as the solvent, leads to a 72 % yield of 2-cyanoquinoxaline. The reaction of trimethylsilyl cyanide and benzoyl chloride with 2,3-diphenylquinoxaline-N-oxide 2 leads to an unexpected ring-opening product 13; its structure is based on spectroscopic data and on an X-ray crystallographic analysis. 相似文献
997.
R. M. Masagutov S. I. Spivak Z. Sh. Akhmadishin G. N. Kirichenko N. G. Grigorieva G. A. Tolstikov 《Reaction Kinetics and Catalysis Letters》1985,28(2):411-417
Kinetics of p-cumylphenol alkylation by isobutylene in the presence of 0.1–2 wt.% p-toluenesulfonic acid has been studied and a reaction scheme is suggested. The rate constants have been determined.
- 0,1–2 % . -. .相似文献
998.
三齿单核三(3,5-二甲基-1-吡唑)硼氢钼配合物Tp*Mo(O)Cl2 (1)(Tp*=三(3,5-二甲基-1-吡唑)硼氢HB(C3H(Me2)N2)3)与含硫族元素碳硼烷的锂盐[(THF)2LiE2C2B10H10(THF)]< 相似文献
999.
Summary A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV detection (270 nm) for the determination of nitrite as its pentafluorobenzyl derivative with and without ion-pair extraction is described. Ion-pair extraction of nitrite from aqueous solutions was performed by using a 1 mol/l solution of the liquid ion exchanger methyltrioctylammonium chloride in toluene. The residue of the ion-pair extraction or an aliquot of an aqueous nitrite solution or of a biological fluid (100 l) were treated with 400 l of acetone and 10 l of pentafluorobenzyl bromide. Nitrite was converted into its pentafluorobenzyl derivative by heating at 50°C for 90 min. After evaporation of acetone the aqueous phases were diluted with 100 to 400 l of methanol, and up to 100 l were injected into the RP-HPLC system. The method allows accurate analysis of nitrite in the presence of nitrate directly in aqueous solutions and biological fluids in concentrations down to 2.0 mg/l. The method is also applicable to the determination of nitrate following its reduction to nitrite by cadmium. 相似文献
1000.
A. Aitmambetov S. N. Shinkaruk S. P. Bondarenko V. P. Khilya 《Chemistry of Natural Compounds》1995,30(4):453-456
6-Halogeno-1,3-benzodioxane analogs of chalcones have been synthesized by various methods. Flavanone and flavone analogs of silandrin and hydnocarpin have been obtained from them. The structures of the new flavonoids have been shown by their PMR spectra.KIEN Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Taras Shevchenko Kiev University, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 494–498, July–August, 1994. 相似文献