全文获取类型
收费全文 | 1353篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 136篇 |
金属工艺 | 10篇 |
机械仪表 | 12篇 |
建筑科学 | 9篇 |
矿业工程 | 1篇 |
能源动力 | 8篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
无线电 | 49篇 |
一般工业技术 | 136篇 |
冶金工业 | 916篇 |
原子能技术 | 4篇 |
自动化技术 | 50篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 23篇 |
2012年 | 12篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 26篇 |
2007年 | 25篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 13篇 |
2000年 | 6篇 |
1999年 | 27篇 |
1998年 | 268篇 |
1997年 | 143篇 |
1996年 | 113篇 |
1995年 | 57篇 |
1994年 | 62篇 |
1993年 | 62篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 28篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 21篇 |
1976年 | 69篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1366条查询结果,搜索用时 14 毫秒
21.
Vinodkumar M Rajagopalan S Bhagwat IP Singh S Parmar BS Mishra OP Upadhyay SS Bhalia NB Deshpande SR 《Food and nutrition bulletin》2007,28(1):100-108
BACKGROUND: Iron and iodine deficiencies affect more than 30% of the world's population. Typical Indian diets contain adequate amounts of iron, but the bioavailability is poor. This serious limiting factor is caused by low intake of meat products rich in heme iron and intake of phytates in staple foods in the Indian diet, which inhibits iron absorption. OBJECTIVE: To test the stability of double-fortified salt (DFS) during storage and to assess its efficacy in improving the iron and iodine status of the communities. METHODS: The stability of both iodized salt and DFS during storage for a 2-year period was determined. The bioefficacy of DFS was assessed in communities covering three states of the country for a period of 1 year. This was a multicenter, single-blind trial covering seven clusters. The experimental group used DFS and the control group used iodized salt. The salts were used in all meals prepared for family members, but determination of hemoglobin by the cyanmethemoglobin method was performed in only two or three members per family, and not in children under 10 years of age (n = 393 and 436 in the experimental and control groups, respectively). The family size was usually four or five, with a male: female ratio of 1:1, consisting of two parents with two or three children. Hemoglobin was measured at baseline, 6 months (midpoint), and 12 months (endpoint). Urinary iodine was measured in only one cluster at baseline and endpoint. All the participants were dewormed at baseline, 6 months, and 12 months. RESULTS: The iron and iodine in the DFS were stable during storage for 2 years. Over a period of 1 year, there was an increase of 1.98 g/dL of hemoglobin in the experimental group and 0.77 g/dL of hemoglobin in the control group; the latter increase may have been due to deworming. The median urinary iodine changed from 200 microg/dL at baseline to 205 microg/dL at the end of the study in the experimental group and from 225 microg/dL to 220 microg/dL in the control group. There was a statistically significant (p < .05) improvement in the median urinary iodine status of subjects who were iodine deficient (urinary iodine < 100 microg/L) in both the experimental and the control groups, a result showing that DFS was as efficient as iodized salt in increasing urinary iodine from a deficient to sufficient status. There was a statistically significant increase (p < .05) in hemoglobin in all seven clusters in the experimental group compared with the control. CONCLUSIONS: The iron and iodine in the DFS are stable in storage for 2 years. The DFS has proved beneficial in the delivery of bioavailable iron and iodine. 相似文献
22.
Sadanand V. Deshpande Jeffrey L. Dupuie Erdogan Gulari 《Advanced functional materials》1996,6(3):135-146
We have applied the novel method of hot filament-activated chemical vapour deposition (HFCVD) for low-temperature deposition of a variety of nitride thin films. In this paper the results from our recent work on aluminium, silicon and titanium nitride have been reviewed. In the HFCVD method a hot tungsten filament (1500–1850°C) was utilised to decompose ammonia in order to deposit nitride films at low substrate temperatures and high rates. The substrate temperatures ranged from 245 to 600°C. The film properties were characterised by a number of analytical and optical methods. The effect of various deposition conditions on film properties was studied. All the films obtained were of high chemical purity and had very low or no detectable tungsten contamination from the filament metal. 相似文献
23.
Pravin Deshpande Aniket Kolekar 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(6):1236-1241
Protection of Metals and Physical Chemistry of Surfaces - Epoxy, Fusion bonded epoxy and conducting polyaniline based paints were applied on low carbon steel sample. Conducting polyaniline and... 相似文献
24.
25.
Kiran B. Deshpande 《Chemical engineering science》2003,58(16):3829-3835
As the holdup of dispersed phase in an agitated liquid-liquid dispersion is increased at fixed agitation, a point is reached (called inversion holdup) when the dispersion inverts—the dispersed phase becomes continuous and vice versa. In this work, we present experimental data which suggest that the inversion holdup for sufficiently intense turbulence is independent of all the operational parameters associated with a stirred tank, e.g., stirrer speed, vessel volume, impeller size, and impeller type; it depends only on the properties of the liquid-liquid system. The inversion holdup was verified to remain unchanged even for inversion in turbulent flow field in the annular space between two coaxial cylinders. A hypothesis involving drops in near contact with each other at high holdups is used to explain the experimental data. The new finding may also provide a qualitative basis for selecting a liquid-liquid system with desired extent of mixing in the dispersed phase for carrying out transport and reactions in multiphase systems. 相似文献
26.
Development of alternate materials to Nafion, based on ionically conducting polymers and their blends is important for the wider applications of proton exchange membrane fuel cells. In this work, blends of sulfonated poly(ether ether ketone) (SPEEK) with poly(ether sulfone) (PES) are investigated. SPEEK with various ion exchange capacity (IEC) was prepared and blended with PES, which is nonionic and hydrophobic in nature. A comparative study of the water uptake, proton conductivity, and thermo‐mechanical characteristics of SPEEK and the blend membranes as a function of the IEC is presented. Addition of PES decreases the water uptake and conductivity of SPEEK. Chemical and thermal stability and mechanical properties of the membrane improve with the addition of PES. The effect of water content on the thermo‐mechanical properties of membranes was also studied. The morphology of blend membranes was studied using SEM to understand the microstructure and miscibility of the components. On the basis of the results, a plausible microstructure of the blends is presented, and is shown to be useful in understanding the variation of different properties with blending. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
27.
R.M. Deshpande A.A. Kelkar A. Sharma C. Julcour-Lebigue H. Delmas 《Chemical engineering science》2011,(8):1631
Biphasic hydroformylation of 1-octene was performed using rhodium sulfoxantphos catalyst dissolved in [BuPy][BF4] ionic liquid. Preliminary experiments proved this system to retain the catalytic complex within the ionic liquid phase and to maintain a high selectivity towards the linear aldehyde (n:iso ratio of 30) over several cycles. Process parameter investigation showed a first order dependence of the initial rate with respect to the catalyst and 1-octene concentrations, but a more complex behavior with respect to hydrogen (fractional order) and carbon monoxide partial pressures (inhibition at high pressures). Different mathematical models were selected based on the trends observed and evaluated for data fitting. Also, rate models were derived from a proposed mechanism, using Christiansen matrix approach. To calculate concentrations of substrates in the catalytic phase as required by this kinetic modeling, solubility measurements were preformed for the gases (pressure drop technique), as well as for 1-octene and n-nonanal (thermogravimetry analysis). 相似文献
28.
We have synthesized a novel enzymatically degradable prodrug system based on poly(ethylene glycol) (PEG) and tyrosine units by employing a synthetic methodology which eliminated the use of conventional blocking and deblocking methodology used for chemical linkage of drug molecule to the pendant ? NH2 group of amino acid. A diester of PEG (6 kDa) and tyrosine hydrochloride was synthesized by dicyclohexyl carbodiimide (DCC)‐mediated condensation. In the second stage, oligomers were prepared by condensing phenolic ? OH groups of tyrosine in the diester with sebacic acid, using DCC. Finally, the hydrochloride salt of tyrosine in the oligomer was treated with triethylamine to activate ? NH2 groups, which were reacted with benzoyl chloride to obtain a model prodrug system. The products synthesized were characterized by IR, 1H‐NMR, and GPC. The spectral data were in accordance with the proposed structures of products. Chymotrypsin‐catalyzed degradation of the oligomers was characterized by both MW measurements and Ninhydrin assay for free tyrosine. Degradation studies indicated that the rate of main‐chain degradation (ester hydrolysis) is higher than that of the side chain (amide hydrolysis). This new, simple methodology should be useful for conjugating a variety of bioactive molecules to enzymatically degradable PEG–amino acid based polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2108–2118, 2002 相似文献
29.
Pravin P. Deshpande Shashikant T. Vagge Sunil P. Jagtap Rajendra S. Khairnar Mahendra A. More 《Journal of Applied Electrochemistry》2002,32(8):5-6
Preface
5th International Symposium on Electrochemical Impedance Spectroscopy Marilleva (Trento), Italy, June 2001 相似文献30.
Rajani Jacob R. Geethu T. Shripathi V. Ganesan U. P. Deshpande Shilpa Tripathi B. Pradeep Rachel Reena Philip 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(2):424-431
The threefold absorption in the fundamental absorption region of the ternary chalcopyrite AgGa7Se12, an ordered defect compound of AgGaSe2, is analyzed to elucidate the three closely spaced band gaps in its valence band due to the lifting of degeneracy of the Γ15 level. Hopfield’s quasi cubic model is employed to extract the crystal-field and spin–orbit splitting parameters and the linear hybridisation of orbitals model for evaluating the percentage contribution of Ag d-orbital and Ga and Se p-orbitals to the p–d hybridization of orbitals. The observed optical properties are correlated with the structural parameters like deformation parameter, anion displacement and anion–cation bond lengths that are deduced from X-ray diffraction data. The compound films for the studies are prepared by a modified form of Gunther’s three temperature technique and the compositional analysis was done by energy dispersive analysis of X-rays. X-ray photoelectron spectroscopy confirms the compound formation while atomic force microscopic technique was used for surface morphological analysis. The electrical resistivity of these n-type semi-conducting films is assessed to be ~5 Ωm and the films are found to be photosensitive. 相似文献