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   774篇
  免费   13篇
电工技术   45篇
综合类   2篇
化学工业   129篇
金属工艺   18篇
机械仪表   15篇
建筑科学   23篇
矿业工程   2篇
能源动力   26篇
轻工业   51篇
水利工程   17篇
无线电   55篇
一般工业技术   159篇
冶金工业   175篇
原子能技术   19篇
自动化技术   51篇
  2024年   1篇
  2023年   2篇
  2022年   10篇
  2021年   14篇
  2020年   8篇
  2019年   8篇
  2018年   10篇
  2017年   6篇
  2016年   15篇
  2015年   7篇
  2014年   19篇
  2013年   27篇
  2012年   27篇
  2011年   42篇
  2010年   30篇
  2009年   36篇
  2008年   31篇
  2007年   50篇
  2006年   40篇
  2005年   22篇
  2004年   32篇
  2003年   32篇
  2002年   25篇
  2001年   19篇
  2000年   12篇
  1999年   17篇
  1998年   84篇
  1997年   35篇
  1996年   33篇
  1995年   17篇
  1994年   12篇
  1993年   18篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1989年   6篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1977年   1篇
  1976年   6篇
  1975年   3篇
  1973年   1篇
排序方式: 共有787条查询结果,搜索用时 15 毫秒
71.
72.
Approximately 80% of hepatocellular carcinoma (HCC) patients in Japan have associated liver cirrhosis, which increases the difficulty of surgical treatment. Liver dysfunction associated with liver cirrhosis is one of the most important predictive prognostic factors for HCC patients. Percutaneous ethanol injection therapy (PEIT) is useful for patients with small HCC or with poor hepatic functional reserve. Transcatheter arterial chemoembolization (TACE) is also useful both for patients with unresectable HCC and patients with multiple intrahepatic recurrence. Liver resection, however, lead to better outcome than other treatments when liver function is maintained after surgery. To determine operative procedures, it is important to evaluate the exact function of remnant liver, based on the preoperative liver function test and the evaluation of tumor character. For advanced HCC patients with vascular invasion, non-surgical treatments such as PEIT or TACE are not indicated, and surgical intervention can be an effective modality to improve their survival. Improvements of surgical technique and perioperative management have decreased fatal complications at a major liver resection and allowed us to carry out liver resection on patients with advanced HCC.  相似文献   
73.
74.
75.
A 200-MHz double-data-rate synchronous-DRAM (DDR-SDRAM) was developed. The chip contains a delay-locked loop (DLL) which performs over a wide range of operating conditions. Post-mold-tuning allows precise replica programming. A 200-MHz intra-chip data bus is suitable for DDR operation  相似文献   
76.
In the present study, the collapse behavior of a plate subjected to axial compression is investigated parametrically using the finite element method. It is shown that the axial collapse of the plate, which has various hardening characteristics, is controlled by two dominant factors: the stress limitation of the material and the limitation of in-plane lateral deformation at the side edges of the plate. Then, a simplified collapse condition, which corresponds to two collapse types, is derived based on the effective width concept and the plastic theory, and the validity of the collapse condition is then verified by the comparison of numerical results obtained under various material and geometric properties. Furthermore, a method for predicting the collapse stress is proposed based on the present collapse condition.  相似文献   
77.
We conducted a multi-site late phase II trial of oral etoposide administered for 21 consecutive days in patients with cervical cancer in cooperation with 32 institutes. Fifty mg/body of oral etoposide was administered daily for 21 consecutive days. Treatment cycles were to be repeated at 4- to 5-week intervals. Eighty patients were enrolled and 70 patients were evaluated. The overall response rate (95% CI), including one complete response patient and 18 partial response patients, was 27.1% (19/70). The most commonly observed toxicity was myelosuppression such as leukopenia, neutropenia, hemoglobin decrease and thrombocytopenia. Other adverse effects were gastrointestinal toxicities such as anorexia, nausea, stomatitis and vomiting, as well as fatigue and alopecia. These adverse effects were well tolerated and controlled with medications. From these results we concluded oral etoposide administered for 21 consecutive days was an effective drug against cervical cancer.  相似文献   
78.
The widespread detection of perfluorinated compounds (PFCs) in the water environment has been a concern for the last several years, while effluents from wastewater treatment facilities are the major sources of these compounds. Even advanced oxidation technologies (AOTs) are not useful for mineralization of the compounds due to their very high stability. Photochemical techniques using particularly vacuum UV (VUV) have been found to be very promising in this regard. But the use of VUV in UV-based AOTs has still not progressed much. Moreover, the impact of water quality on PFCs photomineralization is unknown. This investigation aimed to assess photomineralization potentials of perfluorooctanoic acid (PFOA) in ultrapure water (UPW), tap water (TW), surface water and treated wastewater effluent using a reactor setup enabling maximum utilization of VUV emission of low pressure lamp in laboratory batch experiments. Neya River water (NRW) and the Nakahama Wastewater Treatment Plant Effluent (NWWTPE) represented surface water and treated wastewater effluent respectively. Also, tests were carried out in 50% diluted NRW and NWWTPE. PFOA photomineralization in terms of PFOA removal, defluorination and total organic carbon (TOC) removal are discussed. The usefulness of the method for PFOA mineralization in organic-rich wastewaters, and further research needs are also highlighted.  相似文献   
79.
An integrated ultra micro glutamate sensor has been constructed with a 7 μm diameter platinized carbon-fiber disk (PCD) electrode and a platinum thin-film (PTF) counter electrode fabricated on the glass capillary tube. By platinization, the electrode activity of the carbon fiber is improved. In order to obtain a stable response, a pulse potential is applied for hydrogen peroxide measurement. The PTF counter electrode shows good stability and can be used as a substitute for a silver-silver chloride electrode. Since the integrated PCD electrode shows good characteristics as a hydrogen peroxide sensor, glutamate oxidase is immobilized onto the tip of the PCD electrode to construct the ultra micro glutamate sensor. The sensor shows stable response to glutamate and a response time within 12 s. The calibration range for glutamate measurement is 50–800 μM.  相似文献   
80.
Some properties of boronized layers on steels with direct diode laser   总被引:1,自引:0,他引:1  
Boronized layer on steel is known to be formed by thermal diffusion of boron into the surface of steel improving corrosion-erosion resistant properties. Boronizing is carried out at temperatures ranging from 800 °C to 1050 °C and takes from one to several hours. There is one problem in this process, however, that the structure and properties of the base material are influenced considerably by the high temperature and long time of treatment. In order to avoid the aforementioned drawbacks of pack boronizing and laser-assisted boronizing, a better way is to activate the pack boronizing media and the workpiece with a high density power. The laser boronizing processes do not change the properties of the base material. In this study, the effect of laser characteristics was examined on the laser boronizing of carbon steel. After laser boronizing, the microstructure of the boride layer was analysed with an optical microscope and X-ray diffractometer (XRD). The mechanical properties of borided layer are evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of FeB and Fe2B with thickness ranging 200-300 μm. The laser boronizing process did not change the properties of the base material.  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