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   1152篇
  免费   114篇
电工技术   4篇
综合类   3篇
化学工业   416篇
金属工艺   11篇
机械仪表   15篇
建筑科学   38篇
矿业工程   3篇
能源动力   17篇
轻工业   246篇
水利工程   9篇
石油天然气   8篇
无线电   42篇
一般工业技术   163篇
冶金工业   208篇
原子能技术   3篇
自动化技术   80篇
  2024年   5篇
  2023年   13篇
  2022年   23篇
  2021年   59篇
  2020年   41篇
  2019年   41篇
  2018年   48篇
  2017年   43篇
  2016年   51篇
  2015年   27篇
  2014年   62篇
  2013年   70篇
  2012年   95篇
  2011年   112篇
  2010年   58篇
  2009年   68篇
  2008年   69篇
  2007年   67篇
  2006年   67篇
  2005年   55篇
  2004年   49篇
  2003年   28篇
  2002年   28篇
  2001年   13篇
  2000年   11篇
  1999年   5篇
  1998年   10篇
  1997年   10篇
  1996年   4篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   1篇
  1990年   3篇
  1989年   3篇
  1988年   4篇
  1985年   1篇
  1978年   4篇
  1977年   1篇
排序方式: 共有1266条查询结果,搜索用时 203 毫秒
91.
Integrated development plans (IDPs) are municipal strategic plans designed to bring about developmental local government. They have been criticised for providing insufficient space for democratic participation. This paper explores the extent to which a marginalised group—women—has been incorporated into the IDP process, in response to three questions. First, how have IDP participatory processes incorporated women’s voice, and are the new participatory spaces realising their transformative potential? Secondly, how have women’s interests and a gender perspective been mainstreamed in the IDP, and has it promoted transformation? And finally, at the interface between officials and women themselves, how are IDP projects implemented and does agency promote or impede the goals of gender equality? A study of three KwaZulu-Natal municipalities reveals some achievements, but unequal gender relations have not been transformed. These case studies demonstrate some of the complexities and difficulties in the practice of democratic governance.  相似文献   
92.
Epoxidized soybean oil (ESO) composites were cured with methyl tetrahydrophthalic anhydride (MTHPA) and 2,4,6-tris(dimethylaminomethyl)phenol (DEH 35) as a catalyst, sisal fibers were added at 10% and 30% of percent per weight. Composites curing was monitored using Fourier transform infrared spectroscopy, whereas the thermal stability and the degradation kinetics were investigated using thermogravimetry (TG). ESO/MTHPA/DEH35/S10 and ESO/MTHPA/DEH35/S30 composites displayed curing temperatures approximately 100°C lower related to ESO/MTHPA/DEH35, as well as higher degree of conversion. Sisal addition improved the thermal stability, shifting the weight loss shifting the weight loss onset to higher temperature (from 82 to 120°C). Thermal degradation energy was determined using Friedman, Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models. Sisal significantly increased , especially in the intermediate phase (α = 0.2 and 0.8). The degradation kinetics was investigated by TG, and the degradation mechanisms modeled using Kamal-Sourour, Sestack-Berggren, and 1st order (F1), showed excellent fit, with R2 > 0.99. Acquired results demonstrate that sisal fiber addition benefited the curing process and increased the thermal stability of ESO composites.  相似文献   
93.
BACKGROUND: Pears are exported in large quantities from South Africa, resulting in large revenues. Minimisation of quality losses once the fruit has reached the export destination is as important as following strict export and distribution protocols. Kafirin can form edible films. In this study an edible coating made from 20 g kg?1 kafirin coating solution was applied as a postharvest treatment to retard quality deterioration of ‘Packham's Triumph’ pears during storage at the typical ripening temperature (20 °C). Changes in physicochemical and sensory quality were monitored over a period of 24 days. RESULTS: The kafirin coating was unable to retard the onset of ripening but decreased the respiration rate and retarded the progression of senescence. However, moisture loss was exacerbated in the kafirin‐coated fruit during ripening at 20 °C, especially towards the end of the shelf‐life. CONCLUSION: The kafirin coating extended the eat‐ripe quality of the pears by 1–2 weeks. However, the appearance of the fruit was unacceptable after 14 days of storage in terms of wrinkled skin. Further work is needed to improve the water barrier properties of the kafirin coating by incorporating a wax or triglyceride into the coating formulation or more simply by applying a kafirin coating to waxed fruit. Copyright © 2011 Society of Chemical Industry  相似文献   
94.
95.
96.
Electrospray aerosol generators (EAGs) disperse conducting solutions into air, promptly neutralize the particles to remove the excess charge, and evaporate the residual solvent with a dry air flow. For solutions containing multiple solutes, the particles may become enhanced in the more surface-active solutes. The extent of the enhancement was estimated for nanoparticles electrosprayed from a solution containing NaCl and surfactant sodium dodecyl sulfate (SDS) mixed in a 9:1 weight ratio. A tandem particle mobility analyzer was used to quantify the hygroscopic growth factor (GF). The relative fractions of NaCl and SDS in the particles were estimated from the measured GFs assuming that NaCl and SDS take up water independently of each other. The nanoparticles were considerably enhanced in SDS relative to the starting solution, with the NaCl:SDS weight ratio increasing with the distance from the EAG electrified capillary tip to the neutralizer, and reaching ~1:1 at the longest distances probed. The enhancement in SDS likely occurred during particle fission events as particles traveled from the capillary to the neutralizer. This study has practical ramifications for aerosol nanotechnology and aerosol-assisted drug delivery, which rely on EAG as an instrument of choice for nanoparticle generation.

Copyright 2012 American Association for Aerosol Research  相似文献   
97.
As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer.  相似文献   
98.
Today's rapid rate of technology change introduces both opportunities and challenges for psychologists. A Technology and Practice Questionnaire was sent to 1000 psychologists in independent practice, half of whom were contacted by e-mail and the other half by U.S. mail. A total of 237 of the 433 deliverable surveys sent by U.S. mail were returned (54.7% response rate), but only 49 of the 458 deliverable surveys sent by e-mail (12.9% response rate). Respondents were asked to rate the frequency of 51 behaviors in their practice and to indicate whether the behavior is ethical. The results suggest a relatively low rate of technology use among independent practitioners and a high degree of ethical uncertainty regarding the use of various technologies in practice. Implications for training and practice are considered. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
99.
Double-walled carbon nanotubes (DWCNTs) were selectively functionalised by treatment with concentrated nitric and sulphuric acid, resulting in carboxylated outer and pristine inner tube constituents. The functionalised DWCNTs were then incorporated into two types of pre-existing carbon nanotube (CNT) electrode platforms, and the performance of each was compared to single-walled carbon nanotubes (SWCNTs). To make the CNT electrode platforms DWCNTs were covalently bound to fluorinated tin oxide glass (FTO) or electrografted aminophenyl tether layers on silicon. The performance of single- compared to double-walled CNTs on FTO or silicon supported electrodes was then determined through electrochemical methods, using the redox probes, ferrocene and ruthenium hexaamine, respectively. The DWCNTs showed an improved heterogeneous rate constant. This improvement was attributed to the protection of the electronic properties of the inner wall of the DWCNT during the chemical modification and suggests that DWCNTs may offer a useful alternative to SWCNTs in future electronic devices.  相似文献   
100.
Purpose/Objective: To examine relations between episodes of diabetic ketoacidosis (DKA) and parental warmth, parental negativity, and lack of responsibility for diabetes-related tasks in a sample of youths with Type 1 diabetes (T1D). Research Method/Design: 100 youths with T1D and their caregivers, recruited from an inpatient diabetes unit and an outpatient diabetes clinic, participated. Participants completed disease-specific measures of family functioning (e.g., parental warmth, parent and child perceptions of negativity, family responsibility for diabetes regimen), and medical information (e.g., glycosylated hemoglobin and incidences of DKA) was obtained from medical records. Results: Results showed that higher child perceptions of parental warmth and caring related to the regimen were associated with decreased odds of experiencing a DKA episode. Child reports of higher parental negativity about the regimen were associated with increased odds of experiencing a DKA episode. Reports of who in the family was responsible for the diabetes regimen were not related to episodes of DKA. Conclusions/Implications: Findings suggested that family factors play a significant role in the occurrence or absence of DKA in children's long-term management of diabetes. Future intervention efforts should focus on warmth, caring, and negativity when children and their parents are problem solving and communicating about the diabetes regimen. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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