全文获取类型
收费全文 | 3198篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 61篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
轻工业 | 14篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 2篇 |
一般工业技术 | 17篇 |
冶金工业 | 3100篇 |
原子能技术 | 1篇 |
自动化技术 | 2篇 |
出版年
2020年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 120篇 |
1998年 | 1012篇 |
1997年 | 597篇 |
1996年 | 375篇 |
1995年 | 179篇 |
1994年 | 187篇 |
1993年 | 183篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 28篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 22篇 |
1979年 | 1篇 |
1978年 | 7篇 |
1977年 | 86篇 |
1976年 | 160篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有3204条查询结果,搜索用时 15 毫秒
221.
BACKGROUND: Laparoscopic cholecystectomy (LC) has become firmly established as a procedure of choice for gallstone disease. The procedure usually necessitates general anaesthesia and endotracheal intubation to prevent aspiration and respiratory embarrassment secondary to the induction of pneumoperitoneum. There is a paucity of data in the literature on the procedure being performed under regional (epidural) anaesthesia, especially in patients with coexisting pulmonary disease and pregnancy, who are deemed high risk for general anaesthesia. We report our preliminary experience with LC using epidural anaesthesia in patients with chronic obstructive pulmonary disease (COPD). METHODS: We performed LC in six patients (one man and five women), with a median age of 56 years (range, 38-74), under epidural anaesthesia over an 8-month period. All patients were ASA grade III/IV and the mean FEB1/FVC was 0.52 (range, 0.4-0.68), due to chronic asthma (two cases) and COPD (four cases). They were admitted a day prior to surgery for pulmonary function tests, nebulisers, and chest physiotherapy. An epidural catheter was introduced at T10/11 intervertebral space, and a bolus of 0.5% Bupivacaine was administered. Depending on the patient's pain threshold and the segmental level of analgesia achieved, incremental doses of 2 ml of 0.5% Bupivacaine along with boluses of intravenous 100 mcg Alfentanil was given to each patient. The patients were breathing spontaneously. No nasogastric tube was inserted, and a low-pressure (10 mmHg) pneumoperitoneum was created. LC was performed according to the standard technique. RESULTS: All the patients tolerated the procedure well and made an uneventful postoperative recovery. Median operating time was 50 min; average length of hospital stay was 2.5 days (range, 2-4). The epidural catheter was removed the morning after the operation. Only one patient required postoperative opioid analgesia. Two patients complained of persistent shoulder tip pain during surgery and required intraoperative analgesia (Alfentanil). There was no change in the patient's cardiorespiratory status, including PO2 and pCO2, and no complications occurred either intra- or postoperatively. CONCLUSIONS: LC can be performed safely under epidural anaesthesia in patients with severe COPD. Intraoperative shoulder tip or abdominal pain does not seem to be a major deterrent and can be effectively controlled with small doses of opioid analgesia. 相似文献
222.
223.
224.
RM Zaslavskaia SI Logvinenko AG Logvinenko MM Te?blium 《Canadian Metallurgical Quarterly》1997,(2):23-27
The circadian pattern of hemocoagulation was studied in patients with decompensated rheumatic heart disease (DRHD) concurrent with stages I-II circulatory failure (CF) during complex treatment or medical treatment with disaggregants. Biorhythmological studies demonstrated that in patients with DRHD and CF chronotherapy with curantyl had some advantages over the traditional therapy during complex drug therapy. In these patients, the chronopatterns of circadian rhythms of hemocoagulative parameters tended to normalize under the influence of curantyl chronotherapy, by diminishing the signs of external desynchronization. Advantages of chronotherapy over the traditional treatment found in patients with DRHD and stages I-II CF, as manifested by its clinical effect in shorter periods (on days 4-5) when small daily and course doses of the drug were used. Based on the biorhythmological studies of hemostatic parameters, a method of curantyl chronotherapy was developed for patients with DRHD and stages I-II CF, which may optimize the therapeutical process in patients with this abnormality. 相似文献
225.
F Balada D Sanchis J Virgili MM Grasa C Monserrat JA Fernández-López X Remesar M Alemany 《Canadian Metallurgical Quarterly》1997,105(5):487-495
In previous studies we observed that inhibition of cyclic 3',5'-nucleotide phosphodiesterase (PDE) isozymes, namely isozyme PDE3, suppresses proliferation of rat renal glomerular mesangial cells in vitro and in vivo. To determine whether activation of the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway coupled to specific PDE isozymes modulates accelerated proliferation of renal epithelial cells, we investigated the effect of selective PDE isozyme inhibition on renal epithelial cell proliferation induced in rats by injection of folic acid (FA). In extracts from suspensions of renal cortical tubules, cAMP was metabolized predominantly by isozyme PDE4; activity of PDE3 was about three times lower. The increase in proliferative activity of renal cortical tissue from FA-injected rats, evaluated by immunostaining with Mib-1 antibody, was limited to tubular epithelial cells. Administration of the PDE3 inhibitors cilostazol or cilostamide together with the PDE4 inhibitor rolipram blocked mitogenic synthesis of DNA, as determined by (3H)-thymidine incorporation into renal cortical DNA, in FA-treated rats. FA injection caused an increase of more than 10-fold in proliferating cell nuclear antigen (PCNA) in renal cortical tissue; administration of the potent PDE3 inhibitor lixazinone or, to a lesser degree, cilostazol suppressed these high PCNA levels, whereas rolipram alone had no effect. The results indicate that FA-stimulated in vivo proliferation of renal tubular epithelial cells is down-regulated by activation of a cAMP-PKA signaling pathway linked to PDE3 isozymes. These observations are consistent with the notion that negative crosstalk between cAMP signaling and mitogen-stimulated signaling pathways regulates mitogenesis of renal cells of different terminal differentiation, including tubular epithelial cells. 相似文献
226.
227.
228.
229.
Renal elimination of the bromosulfophthalein-glutathione conjugate (BSP-GSH) after its i.v. administration in the rat in vivo is negligible. In our study we wanted to establish whether the high albumin-binding of BSP-GSH constitutes the major restrictive factor toward the urinary excretion of the compound. The renal disposition of BSP-GSH was studied in the isolated rat kidney during perfusions with or without albumin in the perfusate. The urinary clearance of BSP-GSH in the absence of albumin was very low (< 60 microliters/min) as compared to the inulin clearance (approximately 300 microliters/min). This indicates that albumin-binding is not the major reason for the low urinary clearance of BSP-GSH. Addition of albumin to the perfusate further decreased the urinary excretion by 60%. BSP-GSH is metabolized by the kidney into two major metabolites: the cysteinylglycine conjugate and the di-glutathione conjugate. Both metabolites appear in perfusate, which suggests that BSP-GSH undergoes tubular (re-)uptake. The di-glutathione conjugate is further metabolized to the di-cysteinylglycine conjugate. The di-glutathione conjugate and the di-cysteinylglycine conjugate are the major urinary components and the urinary elimination of BSP-GSH may depend on their formation. Inhibition of gamma-glutamyl transpeptidase activity with acivicin largely prevented the degradation to the cysteinylglycine and dicysteinylglycine conjugates of BSP. The total rate of urinary excretion, however, was only slightly lowered by acivicin. Apparently, cleavage of the gamma-glutamyl moiety is not relevant for the total urinary elimination of BSP-GSH. 相似文献
230.