全文获取类型
收费全文 | 2635篇 |
免费 | 34篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 32篇 |
综合类 | 5篇 |
化学工业 | 327篇 |
金属工艺 | 20篇 |
机械仪表 | 38篇 |
建筑科学 | 82篇 |
矿业工程 | 13篇 |
能源动力 | 21篇 |
轻工业 | 211篇 |
水利工程 | 16篇 |
石油天然气 | 2篇 |
无线电 | 131篇 |
一般工业技术 | 227篇 |
冶金工业 | 1409篇 |
原子能技术 | 13篇 |
自动化技术 | 124篇 |
出版年
2021年 | 19篇 |
2020年 | 17篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 20篇 |
2014年 | 28篇 |
2013年 | 77篇 |
2012年 | 45篇 |
2011年 | 61篇 |
2010年 | 54篇 |
2009年 | 40篇 |
2008年 | 62篇 |
2007年 | 55篇 |
2006年 | 46篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 44篇 |
2002年 | 26篇 |
2001年 | 35篇 |
2000年 | 23篇 |
1999年 | 72篇 |
1998年 | 409篇 |
1997年 | 251篇 |
1996年 | 184篇 |
1995年 | 93篇 |
1994年 | 101篇 |
1993年 | 103篇 |
1992年 | 31篇 |
1991年 | 36篇 |
1990年 | 35篇 |
1989年 | 43篇 |
1988年 | 33篇 |
1987年 | 38篇 |
1986年 | 35篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 19篇 |
1980年 | 25篇 |
1979年 | 11篇 |
1978年 | 22篇 |
1977年 | 47篇 |
1976年 | 100篇 |
1975年 | 20篇 |
1974年 | 12篇 |
1968年 | 9篇 |
1966年 | 10篇 |
排序方式: 共有2671条查询结果,搜索用时 15 毫秒
11.
12.
T Omland T Aarsland A Aakvaag RT Lie K Dickstein 《Canadian Metallurgical Quarterly》1993,72(3):255-259
Case reports from the United Kingdom (UK) in 1989 have suggested that the introduction of human insulin in 1985 was associated with an increased risk of sudden death in insulin-treated diabetic patients. If human insulin increases the risk of sudden death, the number of these should have increased during the period where human insulin was introduced. We therefore identified all cases of sudden death in Denmark in younger insulin-treated diabetic patients, age at death below 50 years. During this period the consumption of human insulin went from 0.2% to 70% of the total consumption in Denmark. The total number of cases fulfilling the inclusion criteria was 226, and the annual number of sudden deaths did not change during the study period (p = 0.14). The number of deaths due to hypoglycaemia and cases with unexplained cause of death also remained constant (test for trend: p = 0.44). Chronic alcohol abuse or acute alcohol intoxication was found in 50% of the 135 patients dying from hypoglycaemia, ketoacidosis or unknown cause of death (including found dead in bed), while this was the case in only 16% of the remaining 91 cases dying from other natural causes. We conclude that introduction of human insulin in Denmark was not followed by an increase in sudden deaths among younger insulin-treated diabetic patients. 相似文献
13.
R. Hopfengärtner M. Lippert W. Dorsch H. Dietrich G. Kreiselmeyer G. Saemann-Ischenko 《Journal of Superconductivity and Novel Magnetism》1994,7(2):319-322
We report on measurements of the in-plane resistivityρ and Hall coefficientR H (B∥c) of various oxygen-deficient epitaxial films of YBa2Cu3O7?x in the normal state. The superconducting transition temperaturesT c of the samples vary from 14 to 90 K. Both the resistivity and the Hall coefficient exhibit a strong dependence on the oxygen content and the temperature. Asx increases,T c decreases continuously, whileρ andR H gradually increase in magnitude. Furthermore, also the characteristic linear dependences ofραT andR Hα T ?1 of the highly doped compounds changes to a nonlinear behavior for the samples withT c lower than 60 K. The unusual doping and temperature dependence ofR H will be compared to the predictions of our calculations, based on a two-dimensional tight-binding model using the relaxation-time approximation. The model considers also the next-nearest-neighbor hopping, which strongly influences the predicted Hall coefficient. Additionally, the cotangent of the Hall angle cot(Θ H ) is discussed in the framework of the two-dimensional Luttinger liquid theory. 相似文献
14.
15.
Five percent of children in the United States have asthma. Status asthmaticus is one of the most common conditions for which children seek care in a pediatric emergency department. beta 2-Agonists such as albuterol are the mainstay of emergency therapy for such children. We present a case of a 4-year-old boy who experienced supraventricular tachycardia (SVT) following albuterol therapy. This is believed to be the first report of adenosine being successfully used to treat a child with albuterol-induced SVT. We also briefly review the recognition and management of SVT in children and the pharmacokinetics of and indications for adenosine. 相似文献
16.
Two cases of congenital absence of a cervical vertebral pedicle are reported. This condition includes hypoplasia of the ipsilateral posterior arch and may predispose to spinal cord injury. The radiographic and computed tomography (CT) findings are reviewed, and the importance of the ipsilateral oblique radiographic view and of CT in diagnosis is stressed. 相似文献
17.
18.
T. S. Shamirzaev A. I. Toropov A. K. Bakarov K. S. Zhuravlev A. Yu. Kobitski H. P. Wagner D. R. T. Zahn 《Semiconductors》2006,40(5):527-533
The stationary and time-resolved polariton radiation in ultrahigh quality AIGaAs layers have been studied. It has been found
that elastic exciton-exciton collisions lead to the appearance of a low-energy line of polariton radiation. We show that the
rate of exciton-to-polariton transitions caused by elastic exciton-exciton collisions is determined not only by the density
of the excitonic gas, but also by its temperature; this is in accordance with existing theoretical predictions.
The text was submitted by the authors in English. 相似文献
19.
20.
MT Yeh TN Mather RT Coughlin C Gingrich-Baker JW Sumner RF Massung 《Canadian Metallurgical Quarterly》1997,35(4):944-947
A new indirect fluorescent-antibody (IFA) assay with antigen produced in vitro in the human promyelocytic leukemia cell line HL60 was used to identify the first recognized case of human granulocytic ehrlichiosis in Rhode Island. This IFA assay was used to detect granulocytic ehrlichiae in white-footed mice and in a dog inhabiting the area surrounding the patient's residence. Host-seeking Ixodes scapularis ticks found in the same habitat also were infected. I. scapularis ticks collected from other locations were fed on dogs and New Zealand White rabbits to assess the competency of these species as hosts of granulocytotropic Ehrlichia. Tick-induced infections of dogs were confirmed by serologic testing, tissue culture isolation, and PCR amplification, whereas several rabbits seroconverted but were PCR and culture negative. PCR amplification of the 16S rRNA gene and DNA sequencing of the PCR products or culture isolation was used to confirm granulocytic Ehrlichia infections in humans, dogs, white-footed mice, and ticks. 相似文献