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61.
62.
本文介绍了近年来我国华东矿区深厚表土层中煤矿立井井壁非采动破裂的特点。分析了井壁破裂的工程地质条件,研究了井壁与土接触面上土─混凝土作用变形和强度参数,并将该接触面视为接触面单元,用弹塑性有限元法,模拟了深厚表土底部含水层失水时土与井壁的相互作用,得到了井壁附加应力随深度和含水层水头降的变化规律,分析了井壁稳定性,揭示了井壁破裂的内在机理。 相似文献
63.
In the present paper reductions of the finite layer mathod once studied in detail by the authors for the elastodynamics of
transverse isotropic bodies are given to several special cases. Two-dimensional problems, axisymmetric problems and static
problems are discussed, respectively, and this finite layer method is also generalized to the problems in which materials
possess viscous properties. Two numerical examples have been presented for the axisymmetric case. From these two examples
it can be concluded that the finite layer method can be used to analyse semi-infinite layered soils and to deal with the problem
of the interaction between soils and structures.
This paper is based on a portion of the author’s dissertation submitted in partial fulfillment of the requirements for the
degree of Ph. D at Shanghai Institute of Appl. Math & Mech., Shanghai. 相似文献
64.
65.
Ari V?is?nen Anne Kiljunen 《International journal of environmental analytical chemistry》2013,93(14):1037-1049
A method for the fast sequential extraction of toxic elements in contaminated soil samples using an ultrasonic water bath, followed by determination with inductively coupled plasma optical emission spectrometry (ICP-OES), was developed and compared with other methods introduced in the literature. The five-step sequential extraction (Tessier scheme) was shortened using ultrasound-assisted sequential extraction (UASE). The optimization of the five-step sequential extraction was based on the analysis of SRM 2710 using Tessiers’s method as a reference. Several extracting solutions with different sonication times and temperatures were tested in the optimization procedure. Concentrations of arsenic, cadmium, copper, lead, and zinc were determined in SRM 2710, SRM 2711, and contaminated soil samples with high accuracy and precision. The certified acid-leachable concentrations of the SRM 2710 were obtained for all elements investigated by using an optimized UASE method. Tessiers’s method yielded total element concentrations that were too high. The determination of zinc in SRM 2711 yielded concentrations that were too low, whereas arsenic determination yielded concentrations that were too high by the UASE method and analysis by ICP-OES. The analysis of the SRMs showed that the UASE method is highly comparable with the other methods used for such purposes. The major advantages of the UASE method are the high treatment rate (40 samples simultaneously with a sonication time of 54 min) and a low sample and reagent usage. 相似文献
66.
Development of a procedure for the multiresidue analysis of pesticides in vineyard soils and its application to real samples 下载免费PDF全文
Eva Pose‐Juan Eliseo Herrero‐Hernández Alba Álvarez‐Martín María J. Sánchez‐Martín M. Sonia Rodríguez‐Cruz 《Journal of separation science》2014,37(16):2215-2224
A procedure for multiresidue analysis was developed for the extraction and determination of 17 pesticides, including herbicides, fungicides, and insecticides, as well as certain degradation products, in vineyard soils from La Rioja region (Spain). Different solvents and mixtures were tested in spiked pesticide‐free soils, and pesticides were comparatively evaluated by gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. Recoveries >70%, with relative standard deviations <9%, were obtained when a mixture of methanol/acetone or a mixture of methanol/CaCl2 0.01 M for the most polar compounds was selected as the extraction solvent. Method validation was accomplished with acceptable linearity (r2 ≥ 0.987) within the concentration range of 0.005–1 μg/mL corresponding to 1.667–333.4 μg/kg and 0.835–167.1 μg/kg for liquid chromatography with mass spectrometry and gas chromatography with mass spectrometry, respectively, and detection limits <0.4 μg/kg for the compounds were studied. The extraction method was applied to 17 real vineyard soil samples, and terbuthylazine and its metabolite desethylterbuthylazine were the most ubiquitous compounds, as they were detected in the 100% of the soils analyzed. The presence of fungicides was also high, and the presence of insecticides was lower than other pesticides. The results confirm the usefulness of the optimized procedure for monitoring residues in vineyard soils. 相似文献
67.
A DUAL-SURFACE DAMAGE MODEL AND EVALUATION FOR NATURAL SOILS WITHIN THE THERMOMECHANICAL FRAMEWORK 总被引:1,自引:0,他引:1
Naturally deposited or residual soils exhibit more complicated behavior than remolded clays. A dual-surface damage model for structured soils is developed based on the thermodynamics framework established in our first paper. The shift stresses and the transformation between the generalized dissipative stress space and actual stress space are established following a systematic procedure. The corresponding constitutive behavior of the proposed model is determined, which reflects the internal structural configuration and damage behavior for geomaterials. Four evolution variables κj^i(i=D, R;j=V, S) and the basic parameters λ, s, v and e0 are introduced to account for the progressive loss of internal structure for natural clays. A series of fully triaxial tests and isotropic compression tests are performed for structured and reconstituted samples of Beijing and Zhengzhou natural clays. The validation of the proposed model is examined by comparing the numerical results with the experimental data. 相似文献
68.
本文研究了用10%N_(7402)-MIBK萃取预富集,以XRFS测定岩石、土壤中Pb、Zn、Cu、Cd、Mo、Bi、Sn等痕量元素的方法,并研究了背景对检出限的影响,选Sm作内标。确定了样品分解,薄样制备方法和测定条件,检出限较直接粉末压片法约降低两个数量级,精密度通常优于4%,本法分析结果与标样推荐值吻合。 相似文献
69.
The elemental and isotopic composition of Ne, Ar, Kr and Xe were measured in the bulk soil samples obtained from Luna 16 and
20 missions. The average cosmic ray exposure ages for the Luna 16 soils is higher than that of Luna 20 soils. The trapped
solar wind composition is deduced by correcting for the cosmogenic component and is found to be in good agreement with the
values published by others. The correlation between the solar wind gases and cosmic ray tracks in lunar samples is quantitatively
studied and some systematic features regarding lunar regolith dynamics are tentatively established. 相似文献
70.
电感耦合等离子体质谱法测定农产品土壤中痕量稀土元素 总被引:1,自引:1,他引:0
建立了电感耦合等离子体质谱法(ICP-MS)测定农产品土壤中15个稀土元素的分析方法.研究了溶样体系用量、标准溶液配制、质谱干扰、内标元素的选择.采用HNO3-HF—H2O2体系电热板溶解样品,稀土元素的溶出率较高.用ICP—MS同时测定土壤中的钇、镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥.以Rh、Re双内标在线校正,有效地降低了信号漂移对分析结果的影响.方法检出限为0.0012—0.0071ng/mL.对实际样品进行连续7次测定,方法精密度为0.2%~4.7%,回收率为97%-114%.经国家标准物质验证,结果与标准值相符.方法弥补了微波消解法的不足,且快速、准确,适合于大批量土壤样品分析. 相似文献