全文获取类型
收费全文 | 827篇 |
免费 | 41篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 176篇 |
金属工艺 | 11篇 |
机械仪表 | 24篇 |
建筑科学 | 12篇 |
矿业工程 | 1篇 |
能源动力 | 43篇 |
轻工业 | 101篇 |
水利工程 | 8篇 |
石油天然气 | 1篇 |
无线电 | 94篇 |
一般工业技术 | 161篇 |
冶金工业 | 81篇 |
原子能技术 | 9篇 |
自动化技术 | 141篇 |
出版年
2023年 | 10篇 |
2022年 | 19篇 |
2021年 | 46篇 |
2020年 | 35篇 |
2019年 | 29篇 |
2018年 | 31篇 |
2017年 | 38篇 |
2016年 | 34篇 |
2015年 | 23篇 |
2014年 | 30篇 |
2013年 | 52篇 |
2012年 | 34篇 |
2011年 | 34篇 |
2010年 | 31篇 |
2009年 | 33篇 |
2008年 | 44篇 |
2007年 | 34篇 |
2006年 | 24篇 |
2005年 | 21篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 17篇 |
1999年 | 9篇 |
1998年 | 14篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 16篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 12篇 |
1974年 | 4篇 |
1972年 | 3篇 |
排序方式: 共有876条查询结果,搜索用时 15 毫秒
101.
RB Singh GS Wander A Rastogi PK Shukla A Mittal JP Sharma SK Mehrotra R Kapoor RK Chopra 《Canadian Metallurgical Quarterly》1998,12(4):347-353
Adherence with inhaled beta-agonists and corticosteroids in 24 asthmatic children was tracked over 3 months utilizing the metered-dose inhaler chronolog (MDIC). Patients seldom took all of their medications as prescribed, and failed to take any inhaled corticosteroid doses on a median of 41.8% of days or inhaled beta-agonists on 28.1% of days despite prescribed daily use. Medication nonadherence was correlated with lower levels of asthma knowledge (Asthma Knowledge Questionnaire) and family dysfunction (Family Assessment Device), but not child behavior disorder (Child Behavior Checklist). Patients tended to dramatically over-report medication use. Improved identification of the markers of nonadherence can directly facilitate more efficient targeting of behavioral interventions, resulting in improved adherence, better illness control, and less requirement of urgent medication intervention. 相似文献
102.
Jitendra B Misra Narakkat P Sukumaran Sirish C Verma 《Journal of the science of food and agriculture》1991,54(3):339-345
Cresolase and catecholase activities were determined in tubers of four potato (Solanum tuberosum L) varieties (Kufri Chamatkar, Kufri Chandramukhi, Kufri Sindhuri and C-2703) fertilised with three levels (0, 120, 240 kg K2O ha?1) of either muriate or sulphate of potash. The enzyme activities were also determined separately in the peel and flesh tissues of the tubers of Kufri Chamatkar and C-2703. Differences were observed in the activities between varieties, with highest specific activities in the tubers of Kufri Chamatkar. Peels of both the varieties showed higher cresolase and catecholase activities than the flesh tissue. Application of potassic fertilisers caused a reduction in both the activities in the tuber, peel and flesh tissue. Greater reduction in activities was caused by application of muriate of potash than with the sulphate form. 相似文献
103.
A two-stage dual-gate f.e.t. amplifier with small signal gain of 20 ± 0.75 dB, covering an octave bandwidth (4?8 GHz) and having a dynamic gain control range in excess of 60 dB is reported. The gain frequency response, input and output v.s.w.r. are described as a function of second-gate voltage. The performance of the dual-gate f.e.t. amplifier as a fast r.f. switch is also presented. 相似文献
104.
VJ Schoenbach SE Landis DJ Weber M Mittal GG Koch PH Levine 《Canadian Metallurgical Quarterly》1993,3(3):281-288
Seventy male Fischer 344 (F-344) rats were treated with s.c. injection of (-)deprenyl (0.5 mg/kg, n = 35) or physiological saline (n = 35) 3 times a week from the age of 18 months until the time of their natural death. The fifty percent survival time was 28 months in control animals and 30 months in the deprenyl treated group. The mean survival time after the start of treatment (18 months) and after 24 months were 378.3 +/- 97.4 days (mean +/- SD) and 196.3 +/- 97.4 days, respectively, in deprenyl treated rats and 328.7 +/- 108.8 days and 146.7 +/- 108.7 days in control rats. The increases in average life expectancies caused by deprenyl treatment (15% from 18 months and 34% from 24 months) were both statistically significant (P < 0.05, two-tailed t-test). The average body weights were comparable for both groups but the variation of body weight was greater in control groups, thus excluding the possibility that the life prolonging effect of deprenyl results from reduced dietary intake. The results confirm those of two previous studies (1,2) which reported a significant life prolonging effect of deprenyl in aged rats and lend added support to the results of a study on male F-344 rats where the effect was only marginally significant (16% increase after 24 months, P = 0.048 by one-tailed t test) (2). 相似文献
105.
Aim of this paper is to assess the validity of bone scanning for radiation therapy treatment planning in the skeletal system. Radiation therapy treatment planning in the skeletal system is based on plain film radiographs and bone scanning. Between January 1, 1993 and June 30, 1994, 228 patients were irradiated due to malignancies in the skeletal system. Included were bone metastases, lymphomas, sarcomas and bone invasion of neuroblastoma. The morphological display of the plain film radiographs and the bone scintigraphies were compared and modifications of the target volume due to the scan findings quantified. In 17 of 228 patients (7.5%) the target volume was modified by at least 2 cm due to tumor invasion depicted by radionuclide scanning only. Bone scintigraphy enables a sensitive display of bony invasion in skeletal malignancies. Because of a scan induced alteration of the target volume in 7.5% of the cases, bone scanning cannot be abandoned in RT treatment planning. 相似文献
106.
The present analysis gives the effects of the thermoelectric currents on the quasi-one-dimensional flow of a real gas in a diverging channel. Numerical solutions are obtained for generator and accelerator modes with subsonic and supersonic flows. the variation of current and power density are presented for the special cases of (i) a linearly diverging channel and (ii) a constant velocity channel. It is observed that the rate of change of the transverse current and the power is slower owing to the influence of thermoelectric currents. 相似文献
107.
108.
JD Fulmer MS Sposovska ER von Gal RG Crystal KK Mittal 《Canadian Metallurgical Quarterly》1978,118(1):141-147
Divergent observations suggest that genetic factors contribute to the susceptibility to or clinical course of idiopathic pulmonary fibrosis. To determine whether there is an association between the major histocompatibility (HLA) system and idiopathic pulmonary fibrosis, the distribution of 35 antigens of HLA loci A and B was determined among 33 white patients with idiopathic pulmonary fibrosis and 329 healthy white control subjects. Although certain antigens tended to be more prevalent among patients with idiopathic pulmonary fibrosis compared with control subjects, there were no significant differences in the phenotype frequencies of the HLA-A and HLA-B antigens between these 2 groups. Thus, although subtle associations may exist between the HLA loci and idiopathic pulmonary fibrosis, these results indicate that antigens of the HLA-A and HLA-B loci are not linked with major risk factors in this disease. 相似文献
109.
This paper presents a methodology for dynamic modeling and simulation of a fixture-workpiece system. A simulation approach is required since standards typically do not exist for dynamic situations like machining operations. In addition, an accurate model is developed for the contact interface at each locating and clamping region on the workpiece's surface. An end milling operation is simulated to analyze the effects of various factors on workpiece accuracy and demonstrate the advantage of the simulation approach. The clamping forces required to keep the workpiece in contact with its locators are obtained, and the influences of locator placement, clamp placement, clamping forces, and clamping sequence on linear and angular errors are reported. Elastic effects of the locator-workpiece and clamp-workpiece contacts, yielding nonlinear dynamic equations of motion, are included in the model. Since system dynamics are considered, results are obtained as a function of time. The study compares well with previous experimental work by other investigators, and the method shows promise as a fixture design tool. 相似文献
110.