全文获取类型
收费全文 | 1207篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
化学工业 | 7篇 |
金属工艺 | 2篇 |
建筑科学 | 5篇 |
轻工业 | 3篇 |
一般工业技术 | 3篇 |
冶金工业 | 1187篇 |
自动化技术 | 4篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 1篇 |
2013年 | 2篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2008年 | 1篇 |
2005年 | 3篇 |
2003年 | 4篇 |
1999年 | 41篇 |
1998年 | 382篇 |
1997年 | 206篇 |
1996年 | 145篇 |
1995年 | 75篇 |
1994年 | 69篇 |
1993年 | 71篇 |
1992年 | 4篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1977年 | 28篇 |
1976年 | 68篇 |
1975年 | 10篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1211条查询结果,搜索用时 15 毫秒
161.
162.
163.
164.
Echocardiography in patients of end stage renal failure (non diabetic) on regular haemodialysis revealed increase in left ventricular mass index in comparison to healthy controls. Anaemia, chronic uraemic state and hypertension were the probable contributory factors. 相似文献
165.
OBJECTIVE: To identify characteristics associated with provision of bystander CPR in witnessed out-of-hospital cardiac arrest cases. METHODS: An observational, prospective, cohort study was performed using cardiac arrest cases as identified by emergency medical services (EMS) agencies in Oakland County. MI, from July 1, 1989, to December 31, 1993. All patients who sustained a witnessed arrest prior to arrival of EMS personnel were reviewed. RESULTS: Of the 927 patients meeting entry criteria, the 229 patients receiving bystander CPR were younger: 60.9 +/- 14.7 vs 67.9 +/- 14.7 years (p < 0.01). Most (76.6%) cardiac arrests occurred in the home. In a multivariate logistic model, only the location of arrest outside the home was a significant predictor of receiving bystander CPR [odds ratio (OR) 3.8; 99% CI 2.5, 5.9]. Arrests outside the home were associated with significantly improved outcome, with 18.2% of out-of-home and 8.2% of in-home victims discharged from the hospital alive (OR 2.5; 99% CI 1.4, 4.4). CONCLUSION: Patients who have had witnessed cardiac arrests outside the home are nearly 4 times more likely to receive bystander CPR, and are twice as likely to survive. This observation emphasizes the need for CPR training of family members in the authors' locale. This phenomenon may also represent a significant confounder in studies of out-of-hospital cardiac arrest and resuscitation. 相似文献
166.
167.
The cutaneous lymphocyte-associated antigen (CLA) has been proposed as a homing receptor for the selective migration of memory T cells into the skin. To investigate the effect of group A streptococci (GAS) on the migration of T cells in psoriasis, CLA expression was assessed by double-staining for CD3 and the HECA-452 epitope on peripheral blood T cells from 13 patients with psoriasis, 10 patients with other inflammatory skin diseases and 12 normal controls before and after 7 days culture with a GAS sonicate, Candida albicans (control antigen) or medium. In addition, CLA+, and CLA-, CD3+ CD45RO+ subsets were isolated from individuals in each group and V beta 2 expression and proliferation to GAS studied. Mean CLA expression by freshly isolated T cells was almost identical in the three groups. After culture with GAS, T cells from the psoriatic patients and control showed a significant increase in mean percentage CLA+ expression compared to medium (P < 0.002, P < 0.05, respectively). This induction was inhibited by the addition of anti-IL-12 antibody. However, in psoriatic patients, but not in controls, the GAS-induced increase was significantly greater than that of C. albicans (P < 0.002) and was accompanied by a decrease in T cells positive for the peripheral lymph node homing receptor, L-selectin (P < 0.05). The percentage of V beta 2+ T cells was markedly higher in the CLA+ than in the CLA- T-cell subset in psoriatic patients (P < 0.01) and controls; both subsets proliferated to GAS, in each group. These findings suggest a differential modulation of specific tissue homing receptors on T cells by GAS in psoriasis. 相似文献
168.
169.
BS Pedersen OH Hel? FB J?rgensen H Kromann-Andersen 《Canadian Metallurgical Quarterly》1998,160(50):7259-7262
Appital is a herbal medicine. The aim was to examine its effect in patients with irritable bowel syndrome (IBS). Other diseases were excluded by physical examination, rectoscopy, blood tests and in patients older than 35 years X-ray of the colon or colonoscopy. The study was designed as a double-blind placebo-controlled trial. The patients were randomized to either Appital or placebo. Following two weeks without medicine, the patient had Appital or placebo for eight weeks. Fifty-nine patients were randomized, 47 completed the study. The results were based on symptom scores registered by the patients. The symptom score was significantly reduced in patients treated with Appital (p = 0.002), but when compared to placebo, the difference was insignificant (p = 0.081). We concluded that Appital has no effect in relieving symptoms of IBS compared to placebo, although due to the possibility of type two error we cannot exclude a small, but hardly clinically relevant effect. 相似文献
170.
Prediction of major depression and dysthymia from CES-D scores among ethnic minority adolescents 总被引:5,自引:0,他引:5
CA Prescott JJ McArdle ES Hishinuma RC Johnson RH Miyamoto NN Andrade JL Edman GK Makini LB Nahulu NY Yuen BS Carlton 《Canadian Metallurgical Quarterly》1998,37(5):495-503
Two tumour cell clones, 6D1 and 4C2 cells, which are defective both in the major histocompatibility gene complex (MHC) class I expression and in the endogenous antigen presentation, are recovered with interferon (IFN)-gamma treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN-gamma treatment. The general morphology of these cells was found to be similar to each other and comparable to that of a tumour cell clone, 4A1 cells, of the same origin, normal in MHC class I expression; they exhibited a fibroblast-like appearance and had many blebs on all the cell surfaces, with desmosome-like junctions between cells. On IFN-gamma treatment, surface fine blebs appeared less, and mitochondria became more densely stained. Expression of MHC class I molecules on the cell surface was much higher in the IFN-gamma treated 6D1 and 4C2 cells than in untreated cells, when estimated by immunoelectron microscopy. The addition of an epitope peptide to these cells did not enhance the class I expression, which differed from other antigen presentation-defective cells such as RMA-S cells, nor change the cell surface morphology. 相似文献