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   387篇
  免费   24篇
  国内免费   1篇
电工技术   5篇
综合类   1篇
化学工业   68篇
金属工艺   9篇
机械仪表   10篇
建筑科学   3篇
能源动力   10篇
轻工业   36篇
水利工程   5篇
石油天然气   2篇
无线电   73篇
一般工业技术   98篇
冶金工业   28篇
原子能技术   2篇
自动化技术   62篇
  2023年   8篇
  2022年   23篇
  2021年   33篇
  2020年   15篇
  2019年   25篇
  2018年   21篇
  2017年   23篇
  2016年   19篇
  2015年   13篇
  2014年   20篇
  2013年   30篇
  2012年   17篇
  2011年   31篇
  2010年   20篇
  2009年   9篇
  2008年   7篇
  2007年   11篇
  2006年   6篇
  2005年   3篇
  2004年   5篇
  2003年   7篇
  2002年   4篇
  2001年   2篇
  2000年   3篇
  1999年   3篇
  1998年   8篇
  1997年   5篇
  1996年   11篇
  1995年   5篇
  1994年   5篇
  1993年   9篇
  1992年   3篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1979年   1篇
  1977年   2篇
排序方式: 共有412条查询结果,搜索用时 31 毫秒
31.
In recent years, the textile industry has been forced to develop new technologies to reduce energy and water consumption. The use of ultrasound in textile wet processing is one solution to this problem. The aim of this work was to investigate the effects of ultrasonic energy on the processing of cotton with a cationic softener. For this purpose, cotton fabric was treated with a fatty acid amide derivative cationic softener in water using ultrasonic energy during treatment. The physical properties of the fabrics treated under different conditions are discussed. The results show that the treatment of fabrics with softeners in an ultrasound bath is more effective compared to conventional methods and that it enhances the physical properties of the cotton.  相似文献   
32.
The phenomenon of nanohillock-like defect formation on the surfaces of CR-39 by ultra-short laser irradiation is investigated using an Atomic Force Microscope (AFM) and Raman Scattering. A polymer CR-39 target was exposed to Ti:sapphire 25-fs laser pulses with a central wavelength at 800 nm. Samples were irradiated for different laser fluences both in air and vacuum. Detailed surface topographical features of the bombarded samples were characterized by atomic force microscopy in contact mode in air at room temperature. AFM reveals that the growth of nanohillocks and their features are strongly dependent on the ambient condition, target position from focus, and irradiation fluence. The appearance of these nanohillocks in the range 1–20 nm in height and 10–90 nm in diameter are regarded as typical features for fast electronic processes (correlated with existence of hot electrons) and are explained on the basis of Coulomb explosion. These nanostructures due to localization of laser energy deposition in small areas provide a possible pathway from dense electronic excitation to atomic motion causing permanent structural modification which are well correlated to structural alterations, like crosslinking and chain scissions, inferred from Raman spectroscopy.  相似文献   
33.
Chronic myeloid leukemia course was evaluated versus sex in 271 patients. Chronic stage involved more pronounced leukocytosis, thrombocytosis and splenomegaly in females, the latter showing higher susceptibility to anemia. As a result, treatment has to deal with a greater mass of tumor. A relatively longer survival time in males (44 and 42 months, respectively) suggest a higher effectiveness of therapy in such patients. When diagnosed, leukocytosis, thrombocytosis, enhanced splenomegaly and anemia should be regarded as factors of unfavorable prognosis.  相似文献   
34.
35.
Biodegradable substrates and encapsulating materials play critical roles in the development of an emerging class of semiconductor technology, generally referred as “transient electronics”, whose key characteristic is an ability to dissolve completely, in a controlled manner, upon immersion in ground water or biofluids. The results presented here introduce the use of thin foils of Mo, Fe, W, or Zn as biodegradable substrates and silicate spin‐on‐glass (SOG) materials as insulating and encapsulating layers, with demonstrations of transient active (diode and transistor) and passive (capacitor and inductor) electronic components. Complete measurements of electrical characteristics demonstrate that the device performance can reach levels comparable to those possible with conventional, nontransient materials. Dissolution kinetics of the foils and cytotoxicity tests of the SOG yield information relevant to use in transient electronics for temporary biomedical implants, resorbable environmental monitors, and reduced waste consumer electronics.  相似文献   
36.
The corrosion inhibition of Al-Alloy (Al2024) in 0.5 M nitric acid solution at 30 °C was achieved using 4-4-dimethyloxazolidine-2-thione (DMT) as a corrosion inhibitor. The electrochemical performance of the DMT was studied by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements, and scanning electron microscopic study (SEM). The results indicated that DMT acts as an inhibitor for Al2024 in 0.5 M nitric acid. Polarization curves indicated that DMT was a mixed-type inhibitor. Inhibition efficiencies were observed to be increased with an increase in DMT concentration and attains approximately to 93.4% at 2 mM of DMT in 0.5 M nitric acid. The adsorption of DMT model on Al2024 surface obeyed in accordance with Langmuir adsorption isotherm model. The value of the free energy of adsorption ΔG ads indicated that the adsorption of DMT molecule was a spontaneous process and was typical of physical and chemical adsorption.  相似文献   
37.
The yield of upper gastrointestinal endoscopy (esophago-gastroduodenoscopy; EGD) in human immunodeficiency virus (HIV)-infected patients based on presenting symptoms has not been well studied. We studied consecutive patients with documented HIV infection undergoing EGD at a large innercity hospital between August 1, 1990 and December 31, 1993; all had presenting symptoms and indications for EGD prospectively recorded at the time of EGD. All endoscopic abnormalities were routinely subjected to biopsy, and extensive histopathological evaluation was performed. EGD was considered helpful when the findings stimulated specific therapeutic intervention other than antifungal or antacid medications. The specific indications for EGD in 156 patients were as follows: esophageal symptoms, 102 patients (65%); abdominal pain, 18 (12%); upper gastrointestinal bleeding, 25 (16%); refractory nausea and vomiting, 11 (7%). Overall, pathologic findings were identified in 116 patients (74%): in refractory esophageal symptoms, 82%; upper gastrointestinal bleeding, 92%; abdominal pain, 39%; nausea and vomiting, 27%. EGD with biopsy identified a specifically treatable opportunistic disorder other than Candida in 80 patients (51%), including idiopathic esophageal ulcer (22%) or viral esophagitis and/or duodenitis (29%). EGD was not helpful in 22.3% of cases, those involving Candida (12.3%) and peptic ulcer disease (PUD)-related causes (10%). The mean CD4 count of patients with opportunistic pathologic findings (24/mm3, n = 79) was significantly lower than that of patients with PUD/gastroesophageal reflux disease (GERD) (167/mm3, n = 9) or negative EGDs (165/mm3, n = 35). Overall, the results of EGD influenced patient management in 78% of cases. We conclude that selective symptom-specific use of EGD, particularly in patients with esophageal symptoms refractory to antifungal therapy or gastrointestinal bleeding, usually identifies specifically treatable abnormalities, whereas EGD is less useful for the evaluation of abdominal pain or nausea and vomiting.  相似文献   
38.
This study reports on a detailed clinical, electrophysiological, muscle computed tomography (CT) and laboratory investigation carried out on five families with definite linkage to chromosome 2p. Some clinical and laboratory features were common to most of the patients, such as the very high serum creatine kinase (CK) levels (mean 43.70 times the normal). The onset was most frequently in the late teens or early twenties with weakness and wasting of the pelvic girdle muscles. All patients had normal motor milestones and had not complained of any symptoms of muscle disease in early childhood. The clinical course was variable both between and within some families, but was most often slowly progressive. Some variability in the pattern of muscle involvement between the different families has also been observed.  相似文献   
39.
The limb-girdle muscular dystrophies are a clinically and genetically heterogeneous group of disorders. We have studied two large inbred families of different ethnic origin and excluded linkage to LGMD2 on chromosome 15q and SCARMD on chromosome 13. Proceeding to a genomic linkage search, we have now identified linkage to markers D2S134 and D2S136 on chromosome 2p (maximum lod score 3.57 at zero recombination). The phenotype in the two families was similar, with onset in the pelvic girdle musculature in the late teens and usually relatively slow progression. This work identifies a second locus for autosomal recessive limb-girdle muscular dystrophy.  相似文献   
40.
Selective epitaxial growth (SEG) of silicon has not had widespread use as a dielectric isolation technology due to the near sidewall defects at the SiO2/Si interface. These defects are located in the first 1-2 μm of the SEG/sidewall SiO2 interface. Diode junctions intersecting the sidewall and 5 μm removed from the sidewall were fabricated in SEG material using thermally grown silicon dioxide (OX) and thermally nitrided thermal silicon dioxide (NOX) as the field insulating mask. Averaged over 16 devices of each type, diodes fabricated with NOX had much better low current I-V characteristics and minimum ideality factors (1.03) than diodes fabricated with OX field oxides (1.23). Junctions intersecting the NOX field insulator had nearly identical characteristics to bulk SEG  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