全文获取类型
收费全文 | 3855篇 |
免费 | 2篇 |
专业分类
化学工业 | 11篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 3篇 |
冶金工业 | 3800篇 |
自动化技术 | 10篇 |
出版年
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 5篇 |
2003年 | 13篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 137篇 |
1998年 | 1252篇 |
1997年 | 779篇 |
1996年 | 475篇 |
1995年 | 232篇 |
1994年 | 215篇 |
1993年 | 219篇 |
1992年 | 19篇 |
1991年 | 31篇 |
1990年 | 35篇 |
1989年 | 46篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 23篇 |
1980年 | 28篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 57篇 |
1976年 | 133篇 |
1975年 | 3篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有3857条查询结果,搜索用时 31 毫秒
951.
The introduction of helical computed tomography (CT) has resulted in improved quality of multiplanar reformations and three-dimensional reconstructions in the chest and abdomen and has made CT angiography a clinical reality. These imaging techniques are useful for evaluating the urinary tract, adding a new dimension to its display, resulting in improved diagnosis of renal and perirenal disease. This article reviews the indications and techniques utilized for multiplanar and three-dimensional CT for urology. The advantages and limitations are discussed, and normal and pathologic findings in the urinary tract illustrated. 相似文献
952.
953.
Video-EEG monitoring was done in 26 patients with paroxysmal intractable attacks of uncertain etiology to determine the nature and cause. Two broad categories were identified: Those with prominent motor activity and those with attacks of collapse/limpness. Events were recorded in 16 patients of which 11 showed no abnormality on the simultaneously recorded EEG, thus helping to confirm their diagnosis of pseudoseizures. 相似文献
954.
955.
Polymer liquid-liquid two-phase systems offer a unique opportunity to study the mechanisms of protein stabilization during freezing and freeze-drying. Fourier transform infrared spectroscopy was used to monitor the structural integrity of recombinant hemoglobin frozen and lyophilized in the separated phases of a polyethylene glycol (PEG)-dextran system. Protein in each phase of an equilibrated biphasic PEG-dextran system experiences similar levels of structural protection against freezing stresses despite large differences in polymer concentration. This result further demonstrates previous suggestions that proteins are protected during freezing by the preferential exclusion mechanism. There are, however, distinct differences in the level of structural protection that polymers in equilibrium phases provide to proteins during lyophilization, emphasizing that the mechanisms of protein protection during freezing and drying are fundamentally different. In addition, we provide evidence that phase separation per se occurring during the course of the lyophilization cycle can be detrimental to the structural stability of a protein. 相似文献
956.
PH van der Meide RJ Groenestein MC de Labie J Heeney P Pala M Slaoui 《Canadian Metallurgical Quarterly》1995,24(4):271-281
We investigated whether enumeration of lymphokine-secreting T cells can be used as a quantitative measure to determine the immunogenicity of foreign proteins in rhesus monkeys. In addition, it was assessed whether this approach can supplement and/or substitute for the well-established lymphoproliferation assay. Two candidate vaccine proteins (e.g., HIV-1 gp120 and HSV-2gD) were used as model antigens for immunization. PBMCs from immunized animals were antigenically stimulated and evaluated on their proliferative capacity and lymphokine release at the single cell level. The experiments showed a close quantitative correlation between antigen-triggered proliferative responses and the antigen-induced generation of IL-2 and IFN-gamma producing cells (pc). IL-4pc were found to appear relatively late after the initiation of antigen exposure. The data indicate that ELISPOT assays provide valuable tools for the assessment of the antigenicity of foreign proteins in vivo. 相似文献
957.
958.
F Rypens P Sonigo MC Aubry AL Delezoide F Cessot F Brunelle 《Canadian Metallurgical Quarterly》1996,17(10):1918-1920
Fetal sonography revealed cerebral, facial, and genitourinary abnormalities, prompting MR at 33 weeks' gestational age. Cerebral MR confirmed a thickened corpus callosum and showed open sylvian fissures, abnormal gyri in the frontal lobes, and presumed neuronal heterotopias. An abortion was performed at 34 weeks' gestational age, and pathologic findings corresponded well to the MR manifestations. 相似文献
959.
Constrictive pericarditis is a pathologic condition that may lead to significant morbidity. Definitive management of constrictive pericarditis requires pericardiectomy. A retrospective review of pericardiectomy for constrictive pericarditis at the Ochsner Clinic was undertaken. Twenty-one patients (17 male, four female) underwent pericardiectomy for constrictive pericarditis between January 1969 and June 1994. Ages ranged from 15 to 66 years (mean 41.5 years). Pedal edema, dyspnea, fatigue, and chest pain were the most common symptoms. Fifteen patients had important comorbidities. Preoperative New York Heart Association (NYHA) class was I (2), II (8), III (6), IV (5). Mean preoperative catheterization data, available in 17 patients (81%), demonstrated elevated intracardiac pressures (right atrial 17.4 mm Hg, right ventricular end-diastolic 22.4 mm Hg, pulmonary artery 26.2 mm Hg, pulmonary capillary wedge 20.2 mm Hg, left ventricular end-diastolic 20.1 mm Hg). A total pericardiectomy was performed in nine patients (sternotomy 8, thoracotomy 1). Pericardiectomy limited anteriorly to the phrenic nerves was performed in 11 patients (sternotomy 9, thoracotomy 2). One partial pericardiectomy was performed through a sternotomy. Cardiopulmonary bypass was used in six patients (29%). Mean hospital stay was 12 days (preoperative 4.2, postoperative 7.67). All patients achieved NYHA Class I postoperatively. Sixteen patients were discharged in sinus rhythm. No early mortality (<30 days), or major postoperative complications were observed. Pericardiectomy for pericardial constriction can be performed safely low morbidity and mortality and can favorably impact the natural history of this debilitating condition. 相似文献
960.