全文获取类型
收费全文 | 56篇 |
免费 | 30篇 |
国内免费 | 3篇 |
专业分类
化学 | 33篇 |
晶体学 | 1篇 |
综合类 | 1篇 |
数学 | 35篇 |
物理学 | 19篇 |
出版年
2021年 | 2篇 |
2019年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2004年 | 2篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有89条查询结果,搜索用时 15 毫秒
81.
82.
The quantum-mechanical D-dimensional inverse square potential is analyzed using field-theoretic renormalization techniques. A solution is presented for both the bound-state and scattering sectors of the theory using cutoff and dimensional regularization. In the renormalized version of the theory, there is a strong-coupling regime where quantum-mechanical breaking of scale symmetry takes place through dimensional transmutation, with the creation of a single bound state and of an energy-dependent s-wave scattering matrix element. 相似文献
83.
Comparative effects of different triazole compounds on growth, photosynthetic pigments and carbohydrate metabolism of Solenostemon rotundifolius 总被引:1,自引:1,他引:0
Kishorekumar A Jaleel CA Manivannan P Sankar B Sridharan R Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2007,60(2):207-212
The effects of two triazole compounds, triadimefon and hexaconazole, on the growth and carbohydrate metabolism were studied in Solenostemon rotundifolius Poir., Morton plants under pot culture. Plants were treated with triadimefon at 15mg l(-1) and hexaconazole at 10mg l(-1) separately by soil drenching on 80, 110 and 140 days after planting (DAP). The plants were harvested randomly and growth parameters were studied on 90, 120 and 150 DAP for determining the effect of both the triazole on growth and chlorophyll pigments. These triazole compounds increased the chlorophyll pigments. However, both the treatments decreased the fresh and dry weights of shoot and leaf area. Both these triazole resulted in a marginal increase in starch content and decreased the sugar contents. The carbohydrate metabolizing enzymes alpha- and beta-amylase activities were reduced and invertase activity increased in S. rotundifolius under triadimefon and hexaconazole treatments. 相似文献
84.
Soil applied cobalt alters the nodulation, leg-haemoglobin content and antioxidant status of Glycine max (L.) Merr 总被引:1,自引:0,他引:1
Jayakumar K Vijayarengan P Changxing Z Gomathinayagam M Jaleel CA 《Colloids and surfaces. B, Biointerfaces》2008,67(2):272-275
The present investigation has been carried out to estimate the effect of cobalt on the nodulation leg-haemoglobin content and antioxidant enzyme activities of soybean plants. The experiments were conducted in earthen pots containing 3 kg of air dried soil. The inner surface of pots was lined with polythene sheet. Soybean plants were raised in soil amended with different concentration of cobalt (0, 50, 100, 150, 200 and 250 mg/kg). The root nodule formation, leg-haemoglobin contents and antioxidant enzyme activities were analysed at 15 days intervals, namely 15, 30, 45, 60 and 75 days after sowing (DAS). There found a significant increase in the total number of root nodules, leg-haemoglobin content and antioxidant enzyme activities at 50 mg/kg cobalt application in the soil in all the sampling days when compared to control. Further increase in the cobalt level (100–250 mg/kg) in the soil decreased root nodules formation as well as leg-haemoglobin content antioxidant enzyme activities of soybean plants in all the sampling days. 相似文献
85.
Water deficit stress effects on reactive oxygen metabolism in Catharanthus roseus; impacts on ajmalicine accumulation 总被引:1,自引:1,他引:0
Jaleel CA Sankar B Murali PV Gomathinayagam M Lakshmanan GM Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2008,62(1):105-111
In the present work, we have analysed the changes in the reactive oxygen metabolism of Catharanthus roseus (L.) G. Don. plants in terms of H(2)O(2) content, lipid peroxidation and the free radical quenching systems (non-enzymatic and enzymatic antioxidants) under drought stress. In addition to this, the root alkaloid ajmalicine was extracted and quantified from both control and drought stressed plants. The H(2)O(2) content was analysed from both stressed and unstressed control plants. Lipid peroxidation was estimated as thiobarbituric acid reactive substances. The non-enzymatic antioxidants viz., ascorbic acid, alpha-tocopherol and reduced glutathione contents, antioxidant enzymes like superoxide dismutase, ascorbate peroxidase, and catalase were extracted and estimated from the samples. The alkaloid ajmalicine was extracted and quantified from shade dried root samples and found significantly increased over control. From the results of this investigation, it can be concluded that the water deficit areas may be well used for the cultivation of medicinal plants like C. roseus and the economically important alkaloid production can be enhanced in the plant level. 相似文献
86.
Manivannan P Jaleel CA Kishorekumar A Sankar B Somasundaram R Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2008,61(2):315-318
A pot culture experiment was conducted to estimate the stress ameliorating ability of paclobutrazol, a triazole fungicide in Vigna unguiculata (L.) Walp. plants. Treatments were given as 80 mM NaCl, 80 mM NaCl + 15 mg l−1 paclobutrazol and 15 mg l−1 paclobutrazol alone. The samples were collected on 60 and 80 days after sowing (DAS). NaCl stress inhibited the root and stem length, total leaf area, fresh weight (FW), dry weight (DW) and activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX). Plants treated with NaCl with paclobutrazol increased these parameters to a larger extent when compared to NaCl stressed plants. The results showed that the paclobutrazol significantly ameliorated the adverse effects of NaCl stress in V. unguiculata plants. 相似文献
87.
Jaleel CA Manivannan P Lakshmanan GM Gomathinayagam M Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2008,61(2):298-303
An experiment was conducted in two varieties, rosea and alba, of Catharanthus roseus plants with two watering treatments viz., 100 and 60% of field capacity, to understand the effects of water deficit on early growth, biomass allocation and photosynthetic pigment responses. We found that there were significant differences in early growth, dry matter accumulation and pigment variations between the two varieties. The root length, shoot length, total leaf area, fresh and dry weights were significantly reduced under water stress treatments. There was a significant reduction in the photosynthetic pigment contents in both the varieties. The rosea variety was more affected due to water deficit when compared to alba variety. 相似文献
88.
Thomas RB Smith PA Jaleel A Vogel P Crawford C Assefa Z Sykora RE 《Inorganic chemistry》2012,51(6):3399-3408
The highly luminescent bimetallic cyanide materials, Gd(terpy)(H(2)O)(NO(3))(2)M(CN)(2) (M = Au, Ag; GdAu and GdAg, respectively) are quick and easy to synthesize under ambient conditions. A characteristic feature exhibited by both solid-state compounds is an intense red emission when excited with UV light. Additionally, GdAu exhibits a broad-band green emission upon excitation in the near UV region. A combination of structural and spectroscopic results for the compounds helps explain the underlying conditions responsible for their unique properties. Single-crystal X-ray diffraction experiments expose their structural features, including the fact that they are isostructural. Crystallographic data for the representative GdAu compound (Mo K(α), λ = 0.71073 ?, T = 290 K): triclinic, space group P ?1, a = 7.5707(3) ?, b = 10.0671(4) ?, c = 15.1260(4) ?, α = 74.923(3)°, β = 78.151(3)°, γ = 88.401(3)°, V = 1089.04(7) ?(3), and Z = 2. Although the compounds crystallize as dimers containing M···M distances smaller than the sum of their van der Waals radii, the Au···Au (3.5054(4) ?) and/or the Ag···Ag (3.6553(5) ?) interactions are relatively weak and are not responsible for the low energy red emission. Rather, the green emission in GdAu presumably originates from the [Au(CN)(2)(-)](2) dimeric excimer, while the [Ag(CN)(2)(-)](2) dimers in GdAg do not display visible emission at either 290 or 77 K. The unusual red emission exhibited by both compounds likely originates from the formation of an excited state exciplex that involves intermolecular π-stacking of 2,2':6',2"-terpyridine ligands. The room-temperature and low-temperature steady-state photoluminescent properties, along with detailed time-dependent, lifetime, and quantum yield spectroscopic data provide evidence regarding the sources of the multiple visible emissions exhibited by these complexes. 相似文献
89.
为了理解化学键的这一结构效应, 本文对具有相同化学键而分子内结构环境不同的系列分子进行了计算研究, 讨论了化学键结构环境对解离能的影响. 相似文献