全文获取类型
收费全文 | 1613篇 |
免费 | 1篇 |
专业分类
综合类 | 52篇 |
化学工业 | 40篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 32篇 |
轻工业 | 10篇 |
水利工程 | 2篇 |
无线电 | 2篇 |
一般工业技术 | 13篇 |
冶金工业 | 1436篇 |
自动化技术 | 25篇 |
出版年
2023年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 18篇 |
2012年 | 16篇 |
2011年 | 11篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 38篇 |
1998年 | 399篇 |
1997年 | 240篇 |
1996年 | 153篇 |
1995年 | 103篇 |
1994年 | 84篇 |
1993年 | 93篇 |
1992年 | 12篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 31篇 |
1988年 | 25篇 |
1987年 | 29篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1978年 | 6篇 |
1977年 | 32篇 |
1976年 | 82篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1614条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
PD Roberts 《Canadian Metallurgical Quarterly》1998,10(7):1831-1846
A general method is presented to classify temporal patterns generated by rhythmic biological networks when synaptic connections and cellular properties are known. The method is discrete in nature and relies on algebraic properties of state transitions and graph theory. Elements of the set of rhythms generated by a network are compared using a metric that quantifies the functional differences among them. The rhythms are then classified according to their location in a metric space. Examples are given, and biological implications are discussed. 相似文献
25.
We report the differences between using either EDTA plasma or serum in a turbidimetric assay for quantitation of C-reactive protein (CRP). A systematic discrepancy was found for these two sample materials. This was most pronounced in the low concentration range (below 20 mg1(-1)) at which lower values were found in serum than in EDTA plasma. Conversely, in the high concentration range, serum showed slightly higher values. Addition of K3-EDTA to the reaction buffer improved the kinetics for sera with low concentrations of CRP, thus increasing the sensitivity of the assay. We found an overall constant discrepancy of approximately 8% lower values in plasma than in serum (equally for low and high levels of CRP) after the addition of K3-EDTA. The most probable explanation for this effect seems to be the differing water content of serum and EDTA plasma. We discuss the role and function of EDTA in the CRP assay and suggest some hypothetical mechanisms. 相似文献
26.
TC Britton PD Thompson BL Day JC Rothwell LJ Findley CD Marsden 《Canadian Metallurgical Quarterly》1993,56(10):1085-1089
The response of postural wrist tremors to supramaximal median nerve stimulation was examined in patients with hereditary essential tremor (n = 10) and Parkinson's disease (n = 9), and in normal subjects mimicking wrist tremor (n = 8). The average frequency of on-going tremor was the same in all three groups. Supramaximal peripheral nerve shocks inhibited and then synchronised the rhythmic electromyographic (EMG) activity of all types of tremor. The duration of inhibition ranged from 90 to 210ms, varying inversely with the frequency of on-going tremor. There was no significant difference in mean duration of inhibition or in the timing of the first peak after stimulation on the average rectified EMG records between the three groups. The degree to which supramaximal peripheral nerve shocks could modulate the timing of rhythmic EMG bursts in the forearm flexor muscles was also quantified by deriving a resetting index. No significant difference in mean resetting index of the three groups was found. These results suggest that such studies cannot be used to differentiate between the common causes of postural wrist tremors. 相似文献
27.
MD Medlock JR Madsen PD Barnes DS Anthony LE Cohen RM Scott 《Canadian Metallurgical Quarterly》1997,27(3):121-128
There are many in vivo animal models for studying airway mucus secretion and hypersecretion, each with advantages and disadvantages. Use of a particular test system will depend upon the aspect of secretion to be modelled. Airway hypersecretory diseases exhibit chronic mucus hypersecretion, of which the clinical impact is predominantly in the distal airways. The majority of documented test preparations study acute secretion, invariably using tracheal preparations, but have been invaluable in elucidating the normal physiology of airway mucus secretion. Chronic models of the hypersecretory state in the distal airways have been developed, but are predominantly histologic in nature (for example quantification of increased goblet cell number). There are few investigations of mucus hypersecretion. Examination of the 'antisecretory' potential of pharmaceutical compounds has been investigated predominantly in chronic histologic models with the drug being given 'prophylactically' rather than 'therapeutically'. Refinement of chronic hypersecretory models should lead to elucidation of the connection between airway irritation, inflammation, MUC gene expression, mucous cell hyperplasia/metaplasia, airway hypersecretion and bronchial hypersecretory disease. 相似文献
28.
29.
JS Plummer KA Berryman C Cai WL Cody J DiMaio AM Doherty JJ Edmunds JX He DR Holland S Levesque DR Kent LS Narasimhan JR Rubin ST Rapundalo MA Siddiqui AJ Susser Y St-Denis PD Winocour 《Canadian Metallurgical Quarterly》1998,8(23):3409-3414
The synthesis and antithrombotic activity of a series of nonpeptide bicyclic thrombin inhibitors is described. We have explored the SAR with modifications to the P1 site. The introduction of arginine mimetics at the P1 site led to potent and selective thrombin inhibitors. 相似文献
30.
RT Loder RN Hensinger PD Alburger DD Aronsson JH Beaty DR Roy RP Stanton R Turker 《Canadian Metallurgical Quarterly》1998,18(5):630-636
We reviewed 32 children with 41 radiation-therapy associated slipped capital femoral epiphyses (RTASCFE). Ten were from the authors' institutions and 22 from the literature. Gender distribution was equal. The age at diagnosis of the malignancy was 4.3 +/- 3.1 years; the amount of radiation was 4,240 +/- 1,445 rads. Children with RTASCFE presented younger (10.4 +/- 3.2 years) than a routine SCFE. The average symptom duration was 5 +/- 6 months. Children with RTASCFE are usually thin (median weight, 10th percentile) in contrast to children with typical SCFE, who are usually obese (<95th percentile). The majority (82%) of the slips were mild, compared to routine SCFEs (approximately 50%); 28% were bilateral. There was a positive linear relationship between the age at presentation of the SCFE and the age at diagnosis of the malignancy; there was a negative linear relationship between the age at presentation of the SCFE and the amount of radiation therapy. 相似文献