全文获取类型
收费全文 | 726篇 |
免费 | 20篇 |
专业分类
化学 | 419篇 |
晶体学 | 3篇 |
力学 | 26篇 |
数学 | 63篇 |
物理学 | 235篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 14篇 |
2017年 | 16篇 |
2016年 | 23篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 42篇 |
2012年 | 33篇 |
2011年 | 40篇 |
2010年 | 29篇 |
2009年 | 21篇 |
2008年 | 31篇 |
2007年 | 36篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1973年 | 4篇 |
1972年 | 8篇 |
1966年 | 4篇 |
排序方式: 共有746条查询结果,搜索用时 0 毫秒
31.
32.
33.
34.
Bhagwan S. Garg Ranjana Dixit Asha L. Singh 《Journal of Thermal Analysis and Calorimetry》1990,36(7-8):2567-2582
Three different types of iron(III) complexes, Fe(A)3, Fe(A)2(A') and Fe(A)(A')2, whereA is either piperidyldithiocarbamate or morpholyl dithiocarbamate andA' is glycine(oxine) acetylacetone have been prepared by reacting Fe(III) salt with sodium salt of piperidinedithiocarbamic acid or morpholine-dithiocarbamic acid and acetylacetone(oxine)-glycine in different ratios. The mixed ligand complexes have been characterised by elemental analysis, magnetic susceptibility measurements, infrared, electronic spectral techniques and by thermal analysis. Electronic spectral studies suggests that all the complexes possess distorted octahedral geometry. The magnetic moment of the high spin iron(III) complexes lies in the range of 5.88–6.00 and for low spin lies in the range of 3.36–4.34 B.M. TG studies show one step decomposition of complexes and formation of Fe2O3 at the end of the step. 相似文献
35.
A substoichiometric isotope dilution method was developed for the determination of microgram amounts of manganese. The method involves the use of carrier-free 54Mn with Mn(II) carrier and its complexation with 2-thenoyltrifluoroacetone (TTA) at pH 8.5, the complex then being extracted into isobutyl methyl ketone. A minimum of 50 ng of manganese can be determined. The method was applied to the determination of manganese in several standard reference materials and biological samples such as tea leaves, spices and condiments. The method is simple and fast and yields results with high accuracy and precision. 相似文献
36.
Extensive experimental studies of the Raman spectra of H2O and D2O ice in the lattice translational and OH (OD) stretching regions are reported for the first time at 88 K and from 0→6 kbar. An unambiguous transformation from ice Ih to ice IX has been observed, although previous studies suggest that a transition to ice II would have occurred. The ice Ih data are analysed in terms of various coefficients. 相似文献
37.
R. Garg V. K. Garg I. Czakó-Nagy S. Nagy E. Kuzmann A. Vértes 《Journal of Radioanalytical and Nuclear Chemistry》1994,186(6):455-462
Mössbauer spectroscopy and X-ray diffractometry have been used to study Sm–Fe mixed oxides (with different SmFe atomic ratios) annealed at 550, 850, 1000 and 1250 °C. The room temperature Mössbauer spectra can be interpreted in terms of one, two or three sextets and in some cases by an additional doublet depending on the composition and the heat treatment. The sextets have been associated with SmFeO3 perovskite, Sm3Fe5O12 garnet and -Fe2O3 hematite. These results are in agreement with those of X-ray diffractometric measurements, which give a clear, evidence of the presence of these phases. 相似文献
38.
D. L. Samudralwar R. B. Lanjewar A. N. Garg 《Journal of Radioanalytical and Nuclear Chemistry》1987,119(3):211-221
A radiochemical solvent extraction method has been developed for the micro determination of Mo/VI/ using99Mo tracer. It involves removal of99mTc by ethyl methyl ketone /EMK/ and extraction of Mo with tri-n-butyl phosphate /TBP/ from 5M HCl. Different parameters affecting the extraction such as pH dependence, nature of solvent and interferences due to other radionuclides have been studied. The method can be used up to 2 g of Mo. 相似文献
39.
A simple, rapid, sensitive, and selective method for the spectrophotometric microdetermination of silver(I) using ammonium(2′,3′-dihydroxy pyridyl-4′-azo)benzene-4-arsonate (DHP-4A), a water soluble pyridinol azo dye is proposed. The red colored 1:1 (metal to ligand) complex formed has molar extinction coefficient (ε) 2.95 × 104 1 mol−1 cm−1 and absorbs maximum at 535 nm, in highly alkaline medium. Beer's law is obeyed up to 3.36 ppm and Sandell's sensitivity (for an absorbance 0.001) is 0.0037 μg of Ag(I)/cm2. The silver(I)-(DHP-4A) complex has also been used in the microdetermination of iodide ions using ligand exchange reaction. The optimum concentration range of iodide ions which can reproducibly be determined is 1.27–37.9 μg/10 ml. 相似文献
40.
Garg BS Sharma RK Kumar V Reddy MJ Mittal S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(12):2789-2794
Novel complexes of Co(II), Ni(II), Cu(II) and Pd(II) with the new ligand [N,N'-bis(2-carboxy-1-oxo-phenelenyl)ethylenediamine] (H2L) have been synthesized and characterized on the basis of elemental analyses, magnetic susceptibility, thermal, infrared, electronic, 1H NMR and EPR spectral studies. Infrared and 1H NMR spectra show that H2L acts as a binegative tetradentate ligand. Coordination occurs through deprotonated carboxylate oxygens and nondeprotonated amido nitrogens in all the complexes. Electronic spectral studies and magnetic moment values suggest N2O2 coordination around each metal centre with strong field square planar chromophores. The probable structures of the complexes have been assigned on the basis of spectral studies. The complex formation between M(II) [M(II) = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] and (L2-) has also been studied potentiometrically in 75% aqueous DMF at 25 degrees C in 0.1 M NaClO4. The stability constants were found to follow the order: Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II). 相似文献