全文获取类型
收费全文 | 5802篇 |
免费 | 100篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 16篇 |
综合类 | 3篇 |
化学工业 | 325篇 |
金属工艺 | 30篇 |
机械仪表 | 31篇 |
建筑科学 | 51篇 |
矿业工程 | 6篇 |
能源动力 | 24篇 |
轻工业 | 255篇 |
水利工程 | 11篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 128篇 |
一般工业技术 | 282篇 |
冶金工业 | 4403篇 |
原子能技术 | 19篇 |
自动化技术 | 310篇 |
出版年
2024年 | 9篇 |
2023年 | 17篇 |
2022年 | 17篇 |
2021年 | 36篇 |
2020年 | 34篇 |
2019年 | 31篇 |
2018年 | 59篇 |
2017年 | 57篇 |
2016年 | 59篇 |
2015年 | 56篇 |
2014年 | 62篇 |
2013年 | 113篇 |
2012年 | 117篇 |
2011年 | 92篇 |
2010年 | 82篇 |
2009年 | 67篇 |
2008年 | 87篇 |
2007年 | 73篇 |
2006年 | 60篇 |
2005年 | 38篇 |
2004年 | 52篇 |
2003年 | 37篇 |
2002年 | 39篇 |
2001年 | 32篇 |
2000年 | 20篇 |
1999年 | 149篇 |
1998年 | 1484篇 |
1997年 | 841篇 |
1996年 | 545篇 |
1995年 | 293篇 |
1994年 | 201篇 |
1993年 | 265篇 |
1992年 | 27篇 |
1991年 | 53篇 |
1990年 | 48篇 |
1989年 | 49篇 |
1988年 | 54篇 |
1987年 | 36篇 |
1986年 | 39篇 |
1985年 | 36篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1980年 | 36篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 88篇 |
1976年 | 199篇 |
1975年 | 13篇 |
排序方式: 共有5903条查询结果,搜索用时 0 毫秒
1.
ML Martínez-Frías E Bermejo Sánchez E Rodríguez Pinilla A Villa 《Canadian Metallurgical Quarterly》1997,46(6):593-596
INTRODUCTION: Even though there are few epidemiological studies evaluating the birth weights of different groups of malformed babies with chromosomal abnormalities, it is widely known that infants with trisomy 18, and to a lesser degree those with trisomy 13 and other chromosomal alterations, have low birth weights. PATIENTS AND METHODS: In this study we present the analysis of the birth weights and gestational ages of a large sample of babies (23,155 malformed and a similar number of nonmalformed babies), separating the different groups of chromosomal anomalies and comparing the weight in the clinical groups of malformed infants. RESULTS: Most of the groups with chromosomal abnormalities present lower birth weights in comparison to the other groups. CONCLUSIONS: The results of our study support the conclusion that the relationship between chromosomal alterations and low birth weight is sufficiently important that such a low birth weight in children with minor or major anomalies should be considered as one more indication to perform chromosomal analysis. 相似文献
2.
I. Belda X. Llorà E. Giralt 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2006,10(4):295-304
One of the goals of computational chemistry is the automated de novo design of bioactive molecules. Despite significant progress
in computational approaches to ligand design and efficient evaluation of binding energy, novel procedures for ligand design
are required. Evolutionary computation provides a new approach to this design issue. This paper presents an automated methodology
for computer-aided peptide design based on evolutionary algorithms. It provides an automatic tool for peptide de novo design,
based on protein surface patches defined by user. Regarding the restrictive constrains of this problem a special emphasis has been made on the design of the
evolutionary algorithms implemented. 相似文献
3.
4.
5.
O Bernard B Chachuat A Hélias B Le Dantec B Sialve J-P Steyer L Lardon P Neveu S Lambert J Gallop M Dixon P Ratini A Quintabà S Frattesi J M Lema E Roca G Ruiz J Rodriguez A Franco P Vanrolleghem U Zaher D J W De Pauw K De Neve K Lievens D Dochaine O Schoefs H Fibrianto R Farina V Alcaraz Gonzalez V Gonzalez Alvarez P Lemaire J A Martinez F Esandi O Duclaud J F Lavigne 《Water science and technology》2005,52(1-2):457-464
The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem. 相似文献
6.
7.
GM Gazzaniga G Angelini G Pastorino E Santoro M Lucchini ML Dal Prà 《Canadian Metallurgical Quarterly》1993,78(3):271-275
Four hundred forty-six patients with Tourette Syndrome (TS) and/or their parents completed a 52-item self-report survey about vocal and motor tics, and the frequency of associated co-morbid conditions of aggression, obsessions and compulsions, attentional problems, sleep disturbance, mood disturbance, anxiety, and self-mutilative behaviours which have been frequently reported in the literature on TS. Respondents also responded to an open-ended question regarding the most disabling aspects of TS. Results were analyzed within two age groups; under 18 years of age (N = 245) and 18 years of age or older (N = 177). Tics and associated conditions were the most frequently reported disabling aspect by both age groups. Subjects under age 18, however, reported significantly more frequent problems with hyperactivity, temper control, aggressive behaviours and sleepwalking than adults with TS. 相似文献
8.
9.
A Nu?ez C De la Roza ML Rodrigo-Angulo W Bu?o F Reinoso-Suárez 《Canadian Metallurgical Quarterly》1997,754(1-2):1-11
This study analyses the relationship between the use of rotating instruments, the production of a smear layer and the presence of alterations to enamel microstructures. The rotating instruments used were carbide (8-12 blade) and diamond tipped (30-15 m) cutters. Cavities were made in extracted teeth. Subsequently, half the sample was analysed using the rugosimeter before and after the application of ortophosphoric acid at 35% for 15 and the other half suing a Scansion Electronic microscope (SEM). The results obtained showed on the one hand that carbide cutters leave a smoother surfacer than diamond tipped cutters, and on the other that the smear layer is eliminated better by carbide cutters compared to diamond tipped cutters. Moreover, there are no major traumatic-type alterations at the level of the enamel affecting the microstructure after the use of carbide cutters. 相似文献
10.
Ehrlichia spp. from human and equine sources in the northeastern Unites States were detected by PCR, isolated, and propagated in the HL-60 promyelocytic leukemia cell line. Growth of Ehrlichia from both equine and human sources was enhanced by addition of retinoic acid, which causes granulocytic differentiation of the HL-60 cells. DNA sequencing of a portion of the 16S rDNA gene supported the hypothesis that the same pathogen was responsible for both equine and human granulocytic ehrlichiosis. 相似文献