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   14176篇
  免费   736篇
  国内免费   20篇
电工技术   152篇
综合类   10篇
化学工业   3526篇
金属工艺   266篇
机械仪表   252篇
建筑科学   544篇
矿业工程   18篇
能源动力   504篇
轻工业   2232篇
水利工程   110篇
石油天然气   41篇
无线电   815篇
一般工业技术   2231篇
冶金工业   1787篇
原子能技术   87篇
自动化技术   2357篇
  2024年   26篇
  2023年   111篇
  2022年   463篇
  2021年   531篇
  2020年   300篇
  2019年   365篇
  2018年   536篇
  2017年   490篇
  2016年   542篇
  2015年   372篇
  2014年   564篇
  2013年   877篇
  2012年   838篇
  2011年   1003篇
  2010年   711篇
  2009年   695篇
  2008年   643篇
  2007年   597篇
  2006年   479篇
  2005年   430篇
  2004年   332篇
  2003年   322篇
  2002年   283篇
  2001年   218篇
  2000年   210篇
  1999年   189篇
  1998年   703篇
  1997年   410篇
  1996年   306篇
  1995年   186篇
  1994年   150篇
  1993年   158篇
  1992年   65篇
  1991年   73篇
  1990年   59篇
  1989年   54篇
  1988年   50篇
  1987年   45篇
  1986年   46篇
  1985年   46篇
  1984年   34篇
  1983年   40篇
  1982年   39篇
  1981年   50篇
  1980年   36篇
  1979年   17篇
  1978年   23篇
  1977年   43篇
  1976年   67篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
The cellular neural network (CNN) paradigm is a powerful framework for analogue non-linear processing arrays placed on a regular grid. In this paper we extend the current repertoire of CNN cloning template elements (atoms) by introducing additional non-linear and delay-type characteristics. In addition, architectures with non-uniform processors and neighbourhoods (grid sizes) are introduced. With this generalization, several well-known and powerful analogue array-computing structures can be interpreted as special cases of the CNN. Moreover, we show that the CNN with these generalized cloning templates has a general programmable circuit structure (a prototype machine) with analogue macros and algorithms. the relations with the cellular automaton (CA) and the systolic array (SA) are analysed. Finally, some robust stability results and the state space structure of the dynamics are presented.  相似文献   
112.
The authors describe the cases of two women suffering from AL amyloidosis with affection of the heart muscle in particular. In one of the patients there were also massive amyloid deposits in the lungs which is an exceptional finding. The observations confirm the adverse prognosis of amyloidosis, the rapid progression of the disease after the onset of symptoms of cardiac failure. The first cardial manifestation in both patients were palpitations. The first patient, but not the second one, had a myeloma confirmed on necropsy.  相似文献   
113.
BACKGROUND: The efficacy of squamous cell carcinoma antigen (SCC-Ag) in laryngeal cancer to predict those patients who will relapse after primary treatment (surgery or radiotherapy) and its utility to detect relapses early and thereby increase salvage rates and cure were assessed. METHODS: Sixty healthy donors and 168 patients with laryngeal cancer were included in this prospective trial. Squamous cell carcinoma antigen was measured at diagnosis in all patients, 24 hours and 1 week after surgery in 113 patients and every 10 Gy of administered dose and 2 weeks after treatment in 49 patients primarily referred to radiotherapy. The marker was determined every 3-6 months during follow-up. All patients who relapsed had SCC-Ag studies before and after salvage treatment. RESULTS: The selected cut-off value was 1.5 ngr/ml (mean value in control group, 0.65 + 2 standard deviation [0.38]). Seventy-eight percent of patients with cancer had elevated SCC-Ag values at diagnosis. Squamous cell carcinoma antigen was statistically related to TNM categories (T, P < 0.04; N, P < 0.05; Stage, P < 0.01). Seventy-five percent of those patients with previously elevated pretreatment values normalized after treatment. Incomplete surgical resection (P < 0.0001) or persistence of the disease after radiotherapy (P < 0.01) were related to high posttreatment values. Squamous cell carcinoma antigen was elevated in 88% of the patients who relapsed. In 55% of the recurrences, SCC-Ag was elevated 3 months before pathologic confirmation of relapse. Salvage by surgery or radiotherapy was effective in 70% of the patients. Squamous cell carcinoma antigen posttreatment values were the most important factor in predicting disease free survival (DFS) (P < 0.0001) and overall survival (P < 0.03). CONCLUSIONS: Squamous cell carcinoma antigen is an excellent marker of residual disease after primary treatment that can lead to the addition of other therapeutic procedures (surgery and postoperative radiotherapy). The absence of posttreatment SCC-Ag is the best predictor of DFS, its presence detects recurrence in early stages, permitting salvage of an increased proportion of patients primarily referred for palliative treatment.  相似文献   
114.
115.
116.
The conditions of the preparation of formaldehyde/urea (F/U) resins have been supervised with the aim to reduce formaldehyde emission by influencing the ratio of methylene/dimethylene-ether-bridge linkages in the product. The most crucial point of this task is to keep the pH values of the reacting mixtures on the required level. The effect of formic acid, unevitably present in industrial formaldehyde solutions, was neutralized by applying a new buffer system, containing boric acid and ethylene glycol.  相似文献   
117.
118.
In Slovakia, similarly as in the Czech Republic, marked changes in the pharmaceutical services have gradually been taking place since 1990. Principal legal and organizational changes have been connected also with the extent and standard of provided pharmaceutical services. The present paper reports the results of a questionnaire research regarding the evaluation of the standard of pharmaceutical services in the year 1995 where there existed both state-owned and private public pharmacies. The questionnaire research was carried out in 20 pharmacies of the Region of West Slovakia, 407 questionnaires were evaluated. The questionnaires were evaluated from the viewpoint of sociological classification of respondents (economically active persons, old-age pensioners) as well as the sex of pharmacy customers. The results confirmed relatively little significant differences between the satisfaction with pharmaceutical services either according to the sex or the social position of the respondents. A relatively significant proportion of the respondents have expressed critical views about the participation of the patient in covering the costs of drugs and slow execution of order of drugs.  相似文献   
119.
Impedance spectroscopy and gravimetry were employed to characterize alkyd-acrylate and styrene-acrylate water-borne resin film properties during wetting-through (i.e. during water uptake).  相似文献   
120.
In this paper an original variant of the Schwarz domain decomposition method is introduced for heterogeneous media. This method uses new optimized interface conditions specially designed to take into account the heterogeneity between the sub-domains on each sides of the interfaces. Numerical experiments illustrate the dependency of the proposed method with respect to several parameters, and confirm the robustness and efficiency of this method based on such optimized interface conditions. Several mesh partitions taking into account multiple cross points are considered in these experiments.  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