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   756篇
  免费   44篇
  国内免费   1篇
电工技术   9篇
综合类   2篇
化学工业   406篇
金属工艺   6篇
机械仪表   15篇
建筑科学   26篇
能源动力   26篇
轻工业   102篇
水利工程   6篇
石油天然气   2篇
无线电   35篇
一般工业技术   83篇
冶金工业   24篇
自动化技术   59篇
  2023年   15篇
  2022年   85篇
  2021年   98篇
  2020年   15篇
  2019年   19篇
  2018年   24篇
  2017年   24篇
  2016年   39篇
  2015年   39篇
  2014年   33篇
  2013年   52篇
  2012年   43篇
  2011年   54篇
  2010年   35篇
  2009年   41篇
  2008年   33篇
  2007年   31篇
  2006年   20篇
  2005年   21篇
  2004年   16篇
  2003年   13篇
  2002年   11篇
  2001年   9篇
  2000年   4篇
  1999年   6篇
  1997年   3篇
  1996年   1篇
  1994年   5篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
排序方式: 共有801条查询结果,搜索用时 9 毫秒
31.
32.
Dendritic cells (DCs) are immune specialized cells playing a critical role in promoting immune response against antigens, and may represent important targets for therapeutic interventions in cancer. DCs can be stimulated ex vivo with pro-inflammatory molecules and loaded with tumor-specific antigen(s). Protocols describing the specific details of DCs vaccination manufacturing vary widely, but regardless of the employed protocol, the DCs vaccination safety and its ability to induce antitumor responses is clearly established. Many years of studies have focused on the ability of DCs to provide overall survival benefits at least for a selection of cancer patients. Lessons learned from early trials lead to the hypothesis that, to improve the efficacy of DCs-based immunotherapy, this should be combined with other treatments. Thus, the vaccine’s ultimate role may lie in the combinatorial approaches of DCs-based immunotherapy with chemotherapy and radiotherapy, more than in monotherapy. In this review, we address some key questions regarding the integration of DCs vaccination with multimodality therapy approaches for cancer treatment paradigms.  相似文献   
33.
The inhibiting effect of four innoxious thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole (MAT), 2-mercapto-5-acetylamino-1,3,4-thiadiazole (MAcAT), 2-mercapto-5-methyl-1,3,4-thiadiazole (MMeT) and 2-mercapto-5-phenylamino-1,3,4-thiadiazole (MPhAT)) on bronze corrosion in an aerated solution of 0.2 g L−1 Na2SO4 + 0.2 g L−1 NaHCO3 at pH 5 was studied by potentiodynamic voltammetry and electrochemical impedance spectroscopy.The corrosion parameters determined from the polarisation curves indicate that the addition of the investigated thiadiazole derivatives decreases both cathodic and anodic current densities, due to an inhibition of the corrosion process, through the adsorption of thiadiazoles on the bronze surface. The inhibiting effect of the investigated organic compounds appears to be more pronounced on the anodic process than on the cathodic one and, except for the case MPhAT, it is enhanced by the increases of the inhibitors’ concentration.The adsorption of the thiadiazole derivatives on bronze was confirmed by the presence of the nitrogen atoms in the EDX spectra of the bronze exposed to inhibitor-containing solutions.The magnitude of polarisation resistance values and, consequently, the inhibition efficiencies are influenced by the molecular structure of thiadiazole derivatives. The strongest inhibition was noticed in the presence of compounds with phenyl amino- or amino-functionalities in their molecules. The maximum protection efficiencies were obtained by addition of: 5 mM MAT (95.9%), 1 mM MAcAT (95.7%), 5 mM MMeT (92.6%) and 0.1 mM MPhAT (97%). EIS measurements also revealed that the inhibitor effectiveness of the optimal concentrations of thiadiazole is time-dependent.  相似文献   
34.
The bio hydroxyapatite (HAp) was used from a long time in different medical and environmental applications. The HAp layers with a uniform surface were used for various medical applications such as orthopedic and dental metal implants. In this work, we reported on the influence of X‐ray radiation on the structural and morphological properties of composite layers based on HAp and polydimethylsiloxane (PDMS) deposited on titanium substrates. The HAp:PDMS layers were investigated by different complementary methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and glow discharge optical emission spectrometry (GDOES). FTIR spectral analysis showed that the molecular structure of the coatings was not changed after their irradiation even though, the depth profile analysis performed by GDOES indicated a depletion of Ca and P elements from the HAp:PDMS irradiated samples. By SEM, we showed that the morphological features of the coatings were also changed, as the irradiated layers are delaminated. The biological assays confirmed that the antibacterial activity of HAp:PDMS composite layers increased after irradiation. The results obtained in this study highlighted that the biological properties of HAp:PDMS layers could be influenced by irradiation. POLYM. ENG. SCI., 59:2406–2412, 2019. © 2019 Society of Plastics Engineers  相似文献   
35.
Summary: Syndiotactic polystyrene (sPS)/organophilic clay nanocomposites were obtained by in situ coordination‐insertion polymerization of styrene. Two cationic surfactants (alkylammonium and alkylphosphonium) were used for the intercalation of montmorillonite (MMT). For each organically modified clay, three protocols were performed using an MAO‐activated hemi‐metallocene catalyst, in order to compare the influence of experimental conditions on the composite microstructure and on its thermal stability. The microstructures of nanocomposites were investigated by wide angle X‐ray scattering and DSC. Partially exfoliated or intercalated materials were obtained in all cases and a decrease of crystallinity is observed. Thermal properties were also studied by DSC and thermogravimetric analysis. The presence of clay does not have a strong influence on the sPS thermal transitions but the thermal decomposition process of the material was slowed down in the presence of few organoclay percents, particularly in the degradation beginning. The influence of these two organically modified clays on the thermal stability of the material is discussed.

Gel and suspension formed from the combination of cloisite with toluene (left) and styrene (right), respectively.  相似文献   

36.
Because food ingredients are sometimes considered as causative factors in IgE mediated food allergies, DNA-based tests may prove to be very useful to establish whether allergenic species have been used in foodstuffs production. The development of two SYBR®GreenER™ Real-Time PCR assays, targeting Pru 1 and rbcL genes, based on melting curve analysis, to detect allergen species in food has been presented. Applicability of these methods was assessed with several commercial products containing processed almond.  相似文献   
37.
38.
The properties of melanoidins prepared from glucose and glycine (GG) were investigated by a three step purification protocol consisting of dialysis, gel filtration at high ionic strength and ion metal affinity chromatography. The high molecular weight fraction obtained in the GG system is responsible for 80% of the total brown colour and its antioxidative ability was about 1/4 of that of Trolox measured by the inhibition of linoleic acid oxidation. GG melanoidins have good affinity towards Cu (II) (32% bound to the resin) while it is much lower towards Pb (II) (10%) and Fe (II) (5%). Capillary zone electrophoresis analysis suggests that GG melanoidins are positively charged, although no signal was observed analysing melanoidins by matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry (MALDI-TOF/MS).  相似文献   
39.
Carotenoids from tomatoes inhibit heterocyclic amine formation   总被引:1,自引:0,他引:1  
Tomatoes are a rich source of antioxidants and they are commonly used for meat cooking in Mediterranean countries. The effects of tomato antioxidants on the formation of carcinogenic/mutagenic heterocyclic amines were investigated. A liquid model system containing as precursors creatinine, glucose and glycine in molar concentrations comparable to those present in bovine meat (chemical model system) was employed. A freeze-dried bovine meat juice (meat juice model system) was also used for some experiments. In both model systems, an inhibiting effect of tomato carotenoid fraction on the formation of imidazoquinolines (IQx, MeIQx and DiMeIQx) was observed. Using carotenoid extract at a concentration of 1000 ppm, inhibitions of 36% and 11% of IQx and MeIQx formation respectively in the chemical system and of 13% of MeIQx and of 5% of 4,8-DiMeIQx in the meat juice system was observed. The effect of the main tomato flavonoid, quercetin, was investigated using the meat juice system. Quercetin gave an inhibition of MeIQx formation between 9% and 57% with a maximum effect of 67% at 10 ppm.  相似文献   
40.
Producing sprouts directly during space missions may represent an interesting opportunity to offer high-quality fresh ready to eat food to the astronauts. The goal of this work was to compare, in terms of growth and nutritional quality, rocket (Eruca sativa Mill.) seedlings grown in the International Space Station during the ENEIDE mission with those grown in a ground-based experiment (in presence and absence of clinorotation). The rocket seedlings obtained from the space-experiment were thinner and more elongated than those obtained in the ground-based experiment. Cotyledons were often closed in the seedlings grown in the space experiment. Quantitative (germination, fresh and dry weight) and qualitative (glucose, fructose, sucrose and starch) traits of rocket seedling were negatively affected by micrograv-ity, especially those recorded on seedlings grown under real microgravity conditions The total chlorophyll, and carotenoids of seedlings obtained in the space experiment were strongly reduced in comparison to those obtained in the ground-based experiment (presence and absence of clinorotation). The results showed that it is possible to produce rocket seedlings in the ISS; however, further studies are needed to define the optimal environmental conditions for producing rocket seedlings with high nutritional value  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