全文获取类型
收费全文 | 864篇 |
免费 | 0篇 |
专业分类
化学工业 | 10篇 |
能源动力 | 1篇 |
轻工业 | 2篇 |
无线电 | 2篇 |
一般工业技术 | 3篇 |
冶金工业 | 837篇 |
自动化技术 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 29篇 |
1998年 | 223篇 |
1997年 | 143篇 |
1996年 | 107篇 |
1995年 | 64篇 |
1994年 | 43篇 |
1993年 | 54篇 |
1992年 | 6篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 17篇 |
1983年 | 1篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 13篇 |
1976年 | 47篇 |
排序方式: 共有864条查询结果,搜索用时 31 毫秒
71.
R Simo C Hartley T Malik GE Wilson PH Taylor BK Mandal 《Canadian Metallurgical Quarterly》1998,112(1):77-80
BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being "perpendicular to the skin in every plane" (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. METHODS: Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6-C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. RESULTS: The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 +/- 6.1 degrees (range, 50-78 degrees). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6-C7 level. CONCLUSIONS: These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block. 相似文献
72.
73.
Miguel Angel Cárdenas David García‐López José Francisco Fernández Isabel Gobernado‐Mitre Juan Carlos Merino José María Pastor Juan de Dios Martínez Javier Barbeta Daniel Calveras 《大分子材料与工程》2007,292(9):1035-1046
EVA copolymer/organoclay nanocomposites were prepared using melt‐compounding. Organoclays were obtained using wet and semi‐wet modification methods. These methods enable us to obtain organoclays with adequate modifier incorporation, but organoclays with a homogeneous and narrow agglomeration size distribution were obtained only with the wet method. TS and EB were higher for nanocomposites obtained with organoclays prepared using the wet method. Analysis of Limiting Oxygen Index, UL94 test and Cone Calorimeter test showed that the retardant properties of nanocomposites were also influenced by the kind of modifiers and the modification method.
74.
75.
Research stemming from disengagement and activity theory has recently focused on individual differences in establishing and maintaining interpersonal relationships. A specific intervening variable which has been hypothesized to be related to social activity level is interpersonal cognitive problem solving skills (ICPS). The present study identified two groups of elderly veterans on the basis of their ICPS skills. Those who generated a high number of solutions to interpersonal problems reported significantly more time spent in social and isolated goal-directed tasks than the group generating fewer solutions when age, educational level, and length of institutionalization had been covaried. The results suggest the potential usefulness of the ICPS approach as a means of identifying socially active individuals and as an intervention or training technique for less able institutionalized residents. 相似文献
76.
77.
78.
1. Intracerebroventricular (i.c.v.) injection of choline (25-150 micrograms) increased blood pressure in rats made acutely hypotensive by haemorrhage. Intraperitoneal administration of choline (60 mg kg-1) also increased blood pressure, but to a lesser extent. Following i.c.v. injection of 25 micrograms or 50 micrograms of choline, heart rate did not change, while 100 micrograms or 150 micrograms i.c.v. choline produced a slight and short lasting bradycardia. Choline (150 micrograms) failed to alter the circulating residual volume of blood in haemorrhaged rats. 2. The pressor response to i.c.v. choline (50 micrograms) in haemorrhaged rats was abolished by pretreatment with mecamylamine (50 micrograms, i.c.v.) but not atropine (10 micrograms, i.c.v.). The pressor response to choline was blocked by pretreatment with hemicholinium-3 (20 micrograms, i.c.v.). 3. The pressor response to i.c.v. choline (150 micrograms) was associated with a several fold increase in plasma levels of vasopressin and adrenaline but not of noradrenaline and plasma renin. 4. The pressor response to i.c.v. choline (150 micrograms) was not altered by bilateral adrenalectomy, but was attenuated by systemic administration of either phentolamine (10 mg kg-1) or the vasopressin antagonist [beta-mercapto-beta,beta-cyclopenta-methylenepropionyl1, O-Me-Tyr2,Arg8]-vasopressin (10 micrograms kg-1). 5. It is concluded that the precursor of acetylcholine, choline, can increase and restore blood pressure in acutely haemorrhaged rats by increasing central cholinergic neurotransmission. Nicotinic receptor activation and an increase in plasma vasopressin and adrenaline level appear to be involved in this effect of choline. 相似文献
79.
DL Prout C Zafiratos TN Taddeucci J Ullmann RC Byrd TA Carey P Lisowski JB McClelland LJ Rybarcyk W Sailor W Amian M Braunstein D Lind DJ Mercer D Cooper S DeLucia B Luther DG Marchlenski E Sugarbaker J Rapaport BK Park E Gülmez CA Whitten CD Goodman W Huang D Ciskowski WP Alford 《Canadian Metallurgical Quarterly》1995,52(1):228-242
80.