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   1677篇
  免费   3篇
电工技术   5篇
化学工业   24篇
金属工艺   2篇
机械仪表   5篇
建筑科学   8篇
能源动力   6篇
轻工业   21篇
水利工程   3篇
无线电   23篇
一般工业技术   12篇
冶金工业   1559篇
自动化技术   12篇
  2020年   3篇
  2018年   4篇
  2014年   3篇
  2013年   16篇
  2012年   4篇
  2011年   2篇
  2010年   3篇
  2009年   3篇
  2008年   2篇
  2007年   4篇
  2006年   8篇
  2005年   2篇
  2003年   6篇
  2002年   5篇
  2001年   3篇
  2000年   7篇
  1999年   39篇
  1998年   491篇
  1997年   292篇
  1996年   186篇
  1995年   100篇
  1994年   76篇
  1993年   87篇
  1992年   10篇
  1991年   26篇
  1990年   18篇
  1989年   19篇
  1988年   17篇
  1987年   30篇
  1986年   17篇
  1985年   15篇
  1984年   5篇
  1983年   4篇
  1982年   9篇
  1981年   15篇
  1980年   15篇
  1979年   4篇
  1978年   3篇
  1977年   25篇
  1976年   79篇
  1975年   2篇
  1974年   3篇
  1973年   2篇
  1972年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1965年   2篇
  1955年   1篇
  1932年   1篇
排序方式: 共有1680条查询结果,搜索用时 0 毫秒
41.
AM Steves  SB Dowd  D Durick 《Canadian Metallurgical Quarterly》1997,25(2):86-97; quiz 103, 105
This is the second article of a four-part series on gerontology and its applications to the care of elderly patients in nuclear medicine. This article reviews anatomic and physiologic changes and pathology associated with aging. It also discusses tailoring nuclear medicine procedures according to patients' needs and conditions, as well as adopting changes within the nuclear medicine department to better serve older patients. Upon completion of this article, the reader should be able to: (a) describe normal age-related anatomic and physiologic changes that are observed in older patients; (b) identify common age-related disorders; (c) discuss considerations in tailoring nuclear medicine procedures for older patients; and (d) identify changes in the nuclear medicine facility that would better accommodate older patients.  相似文献   
42.
A stream of unheated crossflow air has been used to make finer melt-blown fibers. Not only are smaller average fiber diameters obtained, but the variation in fiber diameter is smaller. The use of this technique can allow the production of melt-blown nonwovens, which have finer fibers and more uniform webs. Since unheated air is used in the crossflow jet, the fiber enhancement in terms of finer, stronger fibers can be achieved with an energy savings by substituting unheated crossflow air for a portion of the primary air.  相似文献   
43.
44.
The NADYA Group, integrated in the Spanish Society of Parenteral and Enteral Nutrition (SENPE), and made up of professionals dedicated to Artificial Nutrition, and specifically, to Artificial Nutrition in the home, annually undertakes the task of collecting data on diagnosis, type of support, follow up characteristics, complications, and quality of life, of patients included in programs of at home artificial nutrition in Spain. In the Annual Register corresponding to 1994, 17 hospitality groups have participated, providing 369 patients with Home Enteral Nutrition, and 30 with Home Parenteral Nutrition. Home Enteral Nutrition is mainly applied in patients with neoplasias (36%) or neurological alterations (35%). The most commonly used access route in the nasogastric tube, although there is an observed increase in the application of Percutaneous Gastrostomies (21%) in relation to previous data of the Spanish population. There is an observed complications index of 0.07 episodes/patient-year, a mortality of 30% (neoplasias) and 20% (neurological alterations), and low rehabilitation indexes in this group. In Home Parenteral Nutrition, post-radiation enteritis, neoplasias, and mesenteric ischemia, are the main diagnostic groups. The majority of the patients have a tunneled tube (63%), with 37% using an implanted tube. With an index of hospitalizations of 0.83 hospitalizations/ patient-year, catheter septicemia justifies the majority of the re-hospitalizations derived from nutritional treatment (0.56 hospitalizations/patient-year), note the mortality of 37%. There are complete rehabilitations, continuing the previously normal activity in 80% of the cases.  相似文献   
45.
46.
Using high-performance liquid chromatography, gas-chromatography and chromato-mass spectrometry methods a novel endogenous cyclic dipeptide cyclo-prolylglycine was identified in rat brain. Its content according to gas chromatography is 2.8 +/- 0.3 nmol/g wet brain. Synthetic cyclo-prolylglycine has demonstrated antiamnesic activity in the passive avoidance test in rats at a dose of 0.1 mg/kg i.p. Cyclic dipeptide cyclo-prolylglycine seems to be a memory facilitating substance and its presence in rat brain suggests the existence of a new mechanism of memory regulation.  相似文献   
47.
Simultaneous communications combines both spoken and manual modes to produce each word of an utterance. This study investigated the potential influence of alterations in the temporal structure of speech produced by inexperienced signers during simultaneous communication on the perception of final consonant voicing. Inexperienced signers recorded words that differed only in the voicing characteristic of the final consonant under two conditions: (1) speech alone and (2) simultaneous communication. The words were subsequently digitally edited to remove the final consonant and played to 20 listeners who, in a forced-choice paradigm, circled the word they thought they heard. Results indicated that accurate perception of final consonant voicing was not impaired by changes in the temporal structure of speech that accompanied the inexperienced signers' simultaneous communication.  相似文献   
48.
The efficacy of ultrasound compared with ascending venography for the detection of deep venous thrombosis immediately after total knee arthroplasty was assessed after a 2-year interval. One hundred thirty-seven patients were eligible for the study; however, 31 patients received only one of the screening methods and a color Doppler examination was inconclusive in six patients. Therefore, 100 patients had a Doppler examination and a venogram. Overall, the sensitivity of ultrasound was 85%, the specificity 97%, the positive predictive value 85%, the negative predictive value 97%, and the accuracy 95%. The sensitivity in the calf was 83%, in the popliteal vein 86%, and in the femoral vein 100%. Two years ago, the initial assessment of ultrasound for the detection of deep venous thrombosis after surgery in patients who had total joint arthroplasty revealed a 75% sensitivity, 99% specificity, 91% positive predictive value, 97% negative predictive value, and 97% accuracy. The sensitivity in the calf was 83%; the sensitivity in the popliteal vein was 40%; and the sensitivity in the femoral vein was 50%. After 2 years of using this screening test with one technician and one radiologist, an improvement with this noninvasive technique was shown. However, it was found that Doppler imaging is not as sensitive as venography for detecting calf thrombi. Any imaging technique should be validated by each institution to determine the validity of the instrument and the learning curve of the technician administering the examination.  相似文献   
49.
50.
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