首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   262篇
  免费   7篇
电工技术   2篇
化学工业   38篇
金属工艺   18篇
机械仪表   2篇
建筑科学   3篇
能源动力   2篇
轻工业   39篇
水利工程   6篇
石油天然气   1篇
无线电   21篇
一般工业技术   50篇
冶金工业   62篇
原子能技术   4篇
自动化技术   21篇
  2023年   2篇
  2022年   7篇
  2021年   5篇
  2020年   9篇
  2019年   4篇
  2018年   5篇
  2017年   7篇
  2016年   6篇
  2015年   2篇
  2014年   9篇
  2013年   18篇
  2012年   20篇
  2011年   13篇
  2010年   17篇
  2009年   9篇
  2008年   9篇
  2007年   8篇
  2006年   8篇
  2005年   8篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   5篇
  2000年   8篇
  1999年   4篇
  1998年   16篇
  1997年   17篇
  1996年   17篇
  1995年   5篇
  1994年   1篇
  1993年   6篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1985年   2篇
  1981年   3篇
  1980年   3篇
  1979年   1篇
  1976年   1篇
排序方式: 共有269条查询结果,搜索用时 15 毫秒
261.
262.
Roxatidine (150 mg, 312 patients) was compared with ranitidine (300 mg, 308 patients) in a randomized, double-blind, parallel-group, 6-week therapeutic study for the treatment of patients with uncomplicated, benign gastric ulcer disease. The study end points (verified by using endoscopy results) were fully healed ulcers at 4 or 6 weeks. The results of roxatidine therapy were comparable to those of ranitidine therapy: healing rates of 52% and 54% at week 4 and 77% and 76% at week 6 were recorded for roxatidine and ranitidine, respectively. The drugs produced comparable reductions in ulcer diameters and decreases in abdominal pain. Adverse events associated with both roxatidine (27%) and ranitidine (28%) were headache, diarrhea, and dizziness; rash was associated in 6 of 8 cases and in only 1 case with roxatidine. In this trial, roxatidine 150 mg once daily was as efficacious and safe as ranitidine 300 mg once daily for treatment of patients with uncomplicated, benign gastric ulcer disease.  相似文献   
263.
264.
A technique for the synthesis of molecularly imprinted polymers (MIPs) in small scale (~55 mg) coupled with direct in situ processing and batch rebinding evaluation is reported. The primary assessment is based on quantification by HPLC or UV absorbance measurement of the amount of template released from the polymer in a given solvent. This method allows a rapid screening of the parameters of importance to reach a desired level of binding affinity capacity and selectivity for a given target molecule. This was demonstrated for the triazine herbicide terbutylazine, where an initial screening was performed for the type of functional monomer used in the MIP preparation. Thus among the six functional monomers tested, methyl methacrylate, 4-vinylpyridine, and N-vinyl-α-pyrrolidone led to rapid and quantitative extraction whereas methacrylic acid and (trifluoromethyl)acrylic acid led to polymers that retained the template the most. After having established useful functional monomers, a secondary screening for selectivity was performed. In this, nonimprinted blank polymers were prepared and a normal batch rebinding evaluation was performed. The polymer showing the highest selectivity was the one prepared using methacrylic acid as functional monomer. This polymer was shown to strongly retain chlorotriazines including atrazine when a normal-scale batch of the polymer was evaluated in chromatography.  相似文献   
265.
The removal of heavy metal ions by the nonliving biomass of aquatic macrophytes was studied. We investigated Cd biosorption by dry Hydrilla verticillata biomass. Data obtained in batch experiments indicate that H. verticillata is an excellent biosorbent for Cd. Cd was rapidly adsorbed and such adsorption reached equilibrium within 20 min. The initial pH of the solution affected Cd sorption efficiency. Results obtained from the other batch experiments conformed well to those obtained using the Langmuir model. The maximum adsorption capacity q(max) for H. verticillata was 15.0 mg/g for Cd. The breakthrough curve from the continuous flow studies shows that H. verticillata in the fixed-bed column is capable of decreasing Cd concentration from 10 to a value below the detection limit of 0.02 mg/l. The presence of Zn ions affected Cd biosorption. It can be concluded that H. verticillata is a good biosorbent for treating wastewater with a low concentration of Cd contaminants.  相似文献   
266.
The aim of this trial was to investigate the effects that dietary tannins have on lamb intramuscular fatty acids. Twenty-seven lambs were divided into three homogeneous groups: control group, receiving commercial concentrate based on maize; tannin group, fed a diet based on carob pulp (45% as fed basis); PEG group, receiving the same diet as the latter with addition of 42 g/kg of polyethylene glycol (PEG, a binding agent that eliminates the effects of condensed tannins). The duration of the trial was 45 d. Intramuscular fatty acids were measured in the longissimus dorsi muscle. The isomer cis-9 trans-11 of linoleic acid (conjugated linoleic acid or CLA) and linolenic acid were higher in the longissimus muscle fat from animals fed the control diet compared to the other groups (P < 0.0005); these fatty acids were higher in the fat from animals fed the carob diet supplemented with PEG compared to those fed the same diet without PEG (P < 0.05). trans-Vaccenic acid (C18:1 trans-11) was found at higher concentration in fat from control and PEG lambs compared to tannin lambs (P < 0.01); the CLA/C18:1 trans-11 ratio was lower in lambs fed control and PEG diets than in tannin-fed animals (P < 0.05).  相似文献   
267.
Given the lack of data that relates consumer acceptance of lamb colour to instrument measures a study was undertaken to establish the acceptability thresholds for fresh and displayed meat. Consumers (n = 541) were asked to score 20 samples of lamb loin (m.longissimus thoracis et lumborum; LL) on an ordinal scale of 1 (very acceptable) to 5 (very unacceptable). A sample was considered acceptable by a consumer if it scored three or less. Ten samples were used for testing consumer response to fresh colour and 10 to test consumer response to colour during display of up to 4 days. The colour of fresh meat was measured using a Minolta chromameter with a closed cone and a Hunter Lab Miniscan was used for measuring meat on display. For fresh meat when the a (redness) and L (lightness) values are equal to or exceed 9.5 and 34, respectively, on average consumers will consider the meat colour acceptable. However a and L values must be much higher (14.5 and 44, respectively) to have 95% confidence that a randomly selected consumer will consider a sample acceptable. For aged meat, when the wavelength ratio (630/580 nm) and the a values are equal to or greater than 3.3 and 14.8, respectively, on average consumers will consider the meat acceptable. These thresholds need to be increased to 6.8 for ratio (630/580 nm) and 21.7 for a to be 95% confident that a randomly selected consumer will consider a sample acceptable.  相似文献   
268.
In this study, a novel methodology for the electrochemical degradation of benzene in natural water using silver nanoparticle-decorated carbon nanotubes has been investigated. The morphology, the structure, and the electrochemical performance of the multi-walled carbon nanotubes-silver (MWCNT-Ag) nanocomposite film were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. Electrocatalytic oxidation of benzene in an aqueous solution was studied to evaluate potential applications of the MWCNT-Ag modified glassy carbon (GC) electrode in environmental science. The benzene removal efficiency in natural water containing 10 mg L−1 benzene yielded 77.9% at an applied potential of +2.0 V for 2 h using the MWCNT-Ag-GC electrode. In comparison, the removal efficiency reached only 8.0% with the bare GC electrode, showing the suitability of the MWCNT-Ag nanocomposite modified GC electrode for electro-oxidation of benzene in natural water.  相似文献   
269.
Metal terpyridine complexes have gained substantial interest in many application fields, such as catalysis and supramolecular chemistry. In recent years, the biological activity of terpyridine and its metal complexes has aroused considerable regard. On this basis, we synthesised new terpyridine derivatives of trehalose and glucose to improve the water solubility of terpyridine ligands and target them in cancer cells through glucose transporters. Glucose derivative and its copper(II) and iron(II) complexes showed antiproliferative activity. Interestingly, trehalose residue reduced the cytotoxicity of terpyridine. Moreover, we tested the ability of parent terpyridine ligands and their copper complexes to inhibit proteasome activity as an antineoplastic mechanism.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号