全文获取类型
收费全文 | 1491篇 |
免费 | 24篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 115篇 |
金属工艺 | 10篇 |
机械仪表 | 11篇 |
建筑科学 | 11篇 |
能源动力 | 6篇 |
轻工业 | 58篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 52篇 |
一般工业技术 | 83篇 |
冶金工业 | 1093篇 |
原子能技术 | 8篇 |
自动化技术 | 52篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 13篇 |
2013年 | 15篇 |
2012年 | 24篇 |
2011年 | 31篇 |
2010年 | 24篇 |
2009年 | 21篇 |
2008年 | 26篇 |
2007年 | 31篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 34篇 |
1998年 | 326篇 |
1997年 | 195篇 |
1996年 | 121篇 |
1995年 | 65篇 |
1994年 | 73篇 |
1993年 | 78篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1978年 | 8篇 |
1977年 | 38篇 |
1976年 | 85篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1972年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有1515条查询结果,搜索用时 15 毫秒
121.
122.
123.
The following article reviews available data of the interaction of alcohol related liver disease and hepatitis C viral infection as well as special considerations for the treatment of these patients. Alcohol worsens the degree and accelerates the progression of hepatic injury, enhances the risk of developing hepatocellular carcinoma and decreases response to interferon therapy. Patients with hepatitis C should avoid alcohol ingestion. 相似文献
124.
Brian L. Smith William T. Scherer Trisha A. Hauser & B. Brian Park 《Computer-Aided Civil and Infrastructure Engineering》2002,17(6):387-395
Traffic signal systems serve as one of the most powerful control tools available to improve the efficiency of surface transportation travel. A large number of signal systems currently operate using the time–of–day (TOD) approach. In TOD systems, a day is segmented into a number of intervals in which a different timing plan is used. Thus, the challenge in operating a TOD system effectively is to (1) identify appropriate TOD intervals, and (2) develop optimal timing plans for each interval. The existing procedures used by traffic engineers to address these challenges are time consuming and use relatively small sets of data. This research effort developed a new timing plan development methodology that takes advantage of the large sets of archived traffic data (volume and occupancy) that modern systems are equipped to compile. Based upon statistical cluster analysis, this methodology (1) automates the identification of TOD intervals using a high–resolution definition of system state, and (2) provides representative volumes for plan optimization based on the set of archived data. The results of a case study reported in this paper demonstrate that the methodology supports the development of a TOD system that provides benefits when considering performance measures such as delay, when compared to currently used techniques. 相似文献
125.
WJ Rejeski LR Brawley W Ettinger T Morgan C Thompson 《Canadian Metallurgical Quarterly》1997,29(8):977-985
This investigation examined predictors of compliance with exercise therapy in a clinical trial involving older adults with knee osteoarthritis (OA). The study sample was partitioned into tertiles by level of compliance to determine its effect on several clinical outcome measures in the trial (i.e., knee pain, difficulty with activities of daily living, and performance-related disability). The participants (N = 439) first completed all baseline assessments and were then randomly assigned to one of three treatment conditions: health education control, aerobic exercise, or resistance exercise. The two exercise treatments involved a 3-month center-based phase and a 15-month home-based phase. Variables in five categories (i.e., demographic, fitness, health-related quality of life, performance-related disability, and prior exercise behavior) were entered as predictors of attendance and time spent exercising during each session for three different periods of time across the course of the study. Results of these analyses revealed that it was possible to explain more variance for time spent exercising (approximately 40%) during the first 3 months than for attendance (approximately 10%). Furthermore, once participants completed the first 3 months of their training, prior behavior was the strongest predictor of exercise compliance. In most cases, the regression models accounted anywhere from 26 to 46% of the variance in attendance or time spent exercising (7 of the 8 P values < 0.01). In general, demographic, fitness, psychosocial, and disability-related measures did not predict compliance with any consistency across the various phases of the trial. Analysis of the dose-response data suggest that, in the use of aerobic exercise to deter disability in older people with knee OA, consideration should be given to prescribing frequent bouts of activity (at least 3 times each week) of moderate duration (approximately 35 min). 相似文献
126.
127.
LR Alexander AM Spungen MH Liu M Losada WA Bauman 《Canadian Metallurgical Quarterly》1995,76(9):819-822
OBJECTIVE: To determine the overall effect of paraplegia and pressure sores on resting metabolic rate. DESIGN: Unblinded, case-control study using a convenience sample. SETTING: Hospital primary care setting. PATIENTS: Fourteen individuals with paraplegia and pressure sores (PS-Para), 24 with paraplegia in good health (NPS-Para), and 23 non-spinal cord injury (SCI) controls. MAIN OUTCOME MEASURES: The planned outcome measures consisted of resting metabolic rate, percent of predicted resting metabolic rate, resting metabolic rate per kilogram body weight, and resting metabolic rate per meter squared body surface area. Post hoc analyses were used to identify the effect of completeness of lesion, smoking, and pressure sores on percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight. RESULTS: Percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight were significantly higher in the PS-Para group than in the NPS-Para or control groups (115% +/- 4% vs 100% +/- 2% or 107% +/- 2%, p < .05) and (25.9 +/- 1.2 vs 21.4 +/- 0.6 or 22.5 +/- 0.4 kcal/kg, p < .05, respectively). The resting metabolic rate per meter squared body surface area was significantly higher in the PS-Para group than in NPS-Para group (973 +/- 39 vs 874 +/- 20kcal/m2, p < .05). In the PS-Para group, current smokers had significantly higher resting metabolic rate per kilogram body weight than nonsmokers (27.3 +/- 1.7 vs 24.0 +/- 1.4kcal/kg, p < .01). Controlling for the effects of smoking in a multiple regression model, those in the PS-Para group had significantly (p < .001) greater percent of predicted resting metabolic rate and resting metabolic rate per kilogram body weight than those in the NPS-Para group. CONCLUSIONS: These findings indicate that individuals with SCI may have a decreased percent of predicted resting metabolic rate and those with pressure sores may have a hypermetabolic state. This hypermetabolic state is significantly higher than that resulting from smoking. Because ordinary prediction equations for energy expenditure may not be accurate when applied to subjects with paraplegia and pressure sores, quantification of energy needs by indirect calorimetry is recommended. 相似文献
128.
LR Pisharodi 《Canadian Metallurgical Quarterly》1997,41(5):1407-1411
OBJECTIVE: To describe the diagnostic cytologic features of low grade papillary adenocarcinomas of minor salivary gland origin (LPA) along with its pertinent differential diagnostic entities. STUDY DESIGN: The study was based on a histologically confirmed case of LPA that recurred after multiple excisions. Fine needle aspiration (FNA) was performed during the most recent recurrence. RESULTS: Low-power examination showed geographic sheets and papillary groups of epithelial cells. Individual cells were medium sized, with scant cytoplasm, finely clumped chromatin and occasional prominent nucleoli. Pleomorphism was conspicuously absent. Differential diagnosis included cellular mixed tumor, basal cell adenoma, basal cell adenocarcinoma, low grade mucoepidermoid carcinoma and metastatic papillary carcinoma. CONCLUSION: LPA can be accurately diagnosed by FNA biopsy. However, the cytopathologist must entertain and exclude various differential diagnostic entities. 相似文献
129.
With a survey among surgeons and orthopaedic surgeons in German speaking countries the presently applied diagnostic and therapeutic schemes of meniscus lesions were investigated. In 322 questionnaires altogether 43.958 meniscus lesions were reported. In over 90% arthroscopy serves as diagnostic and therapeutic tool. Two thirds of the surgeons suture a longitudinal tear of the outer zone of the meniscus, all the other meniscus lesions were foremost treated by partial resection. The postoperative treatment after meniscus surgery is very inconsistent. Altogether less preserving meniscus operations were performed than it would be possible according to the literature. On one hand new therapy regimens are acknowledged by clinical practice with considerable delay, on the other hand the importance of menisci for the integrity of the knee-joint necessitates a further improvement of reconstructive techniques for preservation of the menisci. 相似文献
130.
SD Detera-Wadleigh JA Badner T Yoshikawa AR Sanders LR Goldin G Turner DY Rollins T Moses JJ Guroff D Kazuba ME Maxwell HJ Edenberg T Foroud D Lahiri JI Nurnberger OC Stine F McMahon DA Meyers D MacKinnon S Simpson M McInnis JR DePaulo J Rice A Goate ES Gershon 《Canadian Metallurgical Quarterly》1997,74(3):254-262