全文获取类型
收费全文 | 4009篇 |
免费 | 80篇 |
专业分类
电工技术 | 21篇 |
化学工业 | 156篇 |
金属工艺 | 6篇 |
机械仪表 | 40篇 |
建筑科学 | 76篇 |
矿业工程 | 6篇 |
能源动力 | 27篇 |
轻工业 | 196篇 |
水利工程 | 8篇 |
石油天然气 | 6篇 |
无线电 | 84篇 |
一般工业技术 | 118篇 |
冶金工业 | 3243篇 |
原子能技术 | 13篇 |
自动化技术 | 89篇 |
出版年
2021年 | 19篇 |
2020年 | 8篇 |
2018年 | 15篇 |
2017年 | 25篇 |
2016年 | 16篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 59篇 |
2012年 | 21篇 |
2011年 | 43篇 |
2010年 | 38篇 |
2009年 | 23篇 |
2008年 | 49篇 |
2007年 | 42篇 |
2006年 | 25篇 |
2005年 | 39篇 |
2004年 | 31篇 |
2003年 | 40篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 27篇 |
1999年 | 110篇 |
1998年 | 1020篇 |
1997年 | 553篇 |
1996年 | 393篇 |
1995年 | 230篇 |
1994年 | 168篇 |
1993年 | 190篇 |
1992年 | 34篇 |
1991年 | 51篇 |
1990年 | 45篇 |
1989年 | 47篇 |
1988年 | 49篇 |
1987年 | 57篇 |
1986年 | 46篇 |
1985年 | 34篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 35篇 |
1981年 | 24篇 |
1980年 | 31篇 |
1979年 | 12篇 |
1978年 | 14篇 |
1977年 | 78篇 |
1976年 | 165篇 |
1975年 | 17篇 |
1974年 | 8篇 |
1973年 | 6篇 |
1971年 | 7篇 |
1969年 | 6篇 |
排序方式: 共有4089条查询结果,搜索用时 328 毫秒
1.
FJ Overdyk PM Gramling-Babb JR Handy NI Faller MJ Miller 《Canadian Metallurgical Quarterly》1997,84(1):213-215
Robertsonian translocations, although relatively common as a constitutional genetic aberration, are rarely encountered in leukaemia. We report a case of acute myeloid leukaemia which showed an acquired Robertsonian translocation in the form of der(14;21) by cytogenetic analysis of leukaemic cells. This was confirmed by the PHA-stimulated culture of peripheral blood lymphocytes. A review of the literature identifies only eight reported cases of acquired Robertsonian translocations in leukaemia. In the majority of cases the Robertsonian translocation occurs as a secondary change in a complex abnormal clone, whereas in two out of nine patients reported, including ours, it is found as a sole karyotypic abnormality. 相似文献
2.
Twenty-six patients with an intracardiac myxoma underwent surgical resection at our institution from 1977 through 1992. Left atrial myxoma was diagnosed in 22 patients, left ventricular in 1, right atrial in 2, and right ventricular in 1. Six patients were asymptomatic; preoperative symptoms included dyspnea, arrhythmias, embolic episodes, and syncope. The diagnosis was established with transthoracic echocardiography in all cases but one. Surgery was performed in all cases with the aid of cardiopulmonary bypass with moderate hypothermia and cold crystalloid cardioplegia. One patient with a left ventricular myxoma died in a comatose state during the immediate postoperative period. Long-term clinical and echocardiographic evaluation was performed in 19 patients; results were excellent (all the patients were in New York Heart Association functional class I or II), and no recurrences were documented. The clinical characteristics, diagnostic methods, and surgical approach are presented and discussed. 相似文献
3.
4.
D Averill D Blockus B Brabson J Brom C Jung H Ogren DR Rust M Derrick P Kooijman JS Loos B Musgrave LE Price J Repond K Sugano B Cork C Akerlof J Chapman D Errede MT Ken DI Meyer H Neal D Nitz R Thun R Tschirhart S Abachi P Baringer BG Bylsma R DeBonte D Koltick EH Low RL McIlwain DH Miller CR Ng EI Shibata 《Canadian Metallurgical Quarterly》1989,39(1):123-137
5.
6.
R. M. Chapman 《Bulletin of Engineering Geology and the Environment》1985,31(1):39-50
Hartebeestfontein Gold Mining Company Limited, which produces 100 kg of gold per working day, has a mining lease area situated mainly over dolomite. A major river nearby governs the regional drainage. The formation of sinkholes and dolines, caused by fluctuations in the water table and the flow of water underground, often accelerated as the result of unavoidable or inadvertent surface activities, is common in such terranes. To maintain production, meticlous ground investigations under new installations plus periodic re-examination and stabilisation under existing ones, particularly key installations, is necessary. The local ground water behaviour pattern is controlled by three impervious major dykes and two major fissure zones, the latter draining surface water into the mine workings. Monthly water table measurements over 25 years show a steady rise to a limit over the area of one fissure zone and a drastic lowering over the other. The value of gravity techniques and thermal infra-red line scanning for cavity detection in the Hartebeestfontein context, is discussed. The procedures followed, for stabilising ground and foundations, are illustrated by means of case histories. The extension of the techniques, learnt from the stabilisation experience, to limiting water seepage into shafts sunk through dolomite, is also discussed. 相似文献
7.
In the testing of mine monitoring systems, a software package was developed for the mine monitoring test facility designed at West Virginia University. The software establishes delay times of sensor input to annunciation for single alarms and multiple simultaneous alarms. The alarm measurement techniques for the test fixture are described, as is the software developed to analyze and graph monitoring system response data. Also included is the analysis capability of the facility, the criteria for evaluating mine monitoring systems, and typical test data from a sample system. 相似文献
8.
9.
JM Bach H Otto GT Nepom G Jung H Cohen J Timsit C Boitard PM van Endert 《Canadian Metallurgical Quarterly》1997,10(4):375-386
Tissue composition and the distribution of body mass are described for four genera of East African Bovidae (Madoqua, Gazella, Damaliscus, Hippotragus) with supporting data from four others (Neotragus, Oryx, Tragelaphus, Connochaetes). These species are high in muscle mass, an adaptation convergent with other high-speed terrestrial cursors, bounders, and saltators. The segments below the elbow/cubitus and knee/stifle/genu joints in small bovids are both lighter in percent of total body mass (8.6% TBM) and less heavily muscled (10-15% of total limb musculature) than those segments in macaques (13.6% TBM, 20-25% of the limb musculature). Bovid species differ from one another in the regional distribution of muscle mass. Madoqua kirkii (4-5 kg) concentrates muscle in the lumbar extensors and hindlimbs; large species such as Damaliscus doreas (50-60 kg) and Hippotragus niger (160-220 kg) distribute it more evenly between the lumbar and cervical regions and between the hindlimbs and forelimbs. Gazella dorcas (10-20 kg) is quantitatively intermediate in those characteristics. The redistribution of muscle mass with increasing size correlates with the loss of axial bending of the vertebral column: in small, hindlimb dominant, 'dorsomobile' species such as Madoqua sagittal mobility increases stride length through 'extended' suspension; in large 'dorsostable' species such as Damaliscus and Hippotragus the vertebral column resists bending, consequently abbreviating or omitting this non-contact phase of the gait cycle. Locomotor adaptation as it is reflected in size, shape, and musculoskeletal structure is the key to habitat choice, dietary specialization, social structure, and male agonistic behavior and, therefore, central to the fabric of behavioral ecology. 相似文献
10.
V Kumar PM Carabateas JA Dority WG Earley JP Mallamo C Subramanyam LD Aimone B Ault DL DeHaven Hudkins MS Miller 《Canadian Metallurgical Quarterly》1995,38(10):1826-1830
Replacement of the pyridinium ring of 6,11-ethanobenzo[b]quinolizinium cations with thiazolium (4a and 4b) and N-methylimidazolium (4c and 4d) resulted in equipotent compounds in the [3H]TCP binding assay. The corresponding N-methyl-1,2,4-triazolium analogs were less potent in this assay. The thiazolium derivative 4b, with a Ki = 2.9 nM, is being evaluated as a possible neuroprotective N-methyl-D-aspartic acid (NMDA) antagonist. 相似文献