全文获取类型
收费全文 | 3180篇 |
免费 | 34篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 41篇 |
综合类 | 28篇 |
化学工业 | 58篇 |
金属工艺 | 12篇 |
机械仪表 | 105篇 |
建筑科学 | 30篇 |
矿业工程 | 6篇 |
能源动力 | 7篇 |
轻工业 | 357篇 |
水利工程 | 2篇 |
无线电 | 15篇 |
一般工业技术 | 111篇 |
冶金工业 | 2334篇 |
原子能技术 | 3篇 |
自动化技术 | 119篇 |
出版年
2022年 | 17篇 |
2020年 | 18篇 |
2019年 | 31篇 |
2018年 | 9篇 |
2016年 | 5篇 |
2014年 | 8篇 |
2013年 | 159篇 |
2012年 | 31篇 |
2011年 | 23篇 |
2010年 | 31篇 |
2009年 | 29篇 |
2008年 | 31篇 |
2007年 | 36篇 |
2006年 | 23篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 24篇 |
2002年 | 16篇 |
2001年 | 6篇 |
2000年 | 14篇 |
1999年 | 84篇 |
1998年 | 760篇 |
1997年 | 439篇 |
1996年 | 291篇 |
1995年 | 157篇 |
1994年 | 126篇 |
1993年 | 152篇 |
1992年 | 27篇 |
1991年 | 32篇 |
1990年 | 43篇 |
1989年 | 40篇 |
1988年 | 39篇 |
1987年 | 54篇 |
1986年 | 38篇 |
1985年 | 38篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 60篇 |
1976年 | 125篇 |
1975年 | 6篇 |
1973年 | 5篇 |
1969年 | 5篇 |
1958年 | 4篇 |
1955年 | 18篇 |
1954年 | 16篇 |
排序方式: 共有3228条查询结果,搜索用时 20 毫秒
11.
The data of nine children with post-traumatic intramural haematoma of the duodenum treated in Aghia Sophia Children's Hospital of Athens from 1967 to 1980 were retrospectively analysed. Diagnosis was preoperative in all but two children, in whom diagnosis was made during laparotomy. All but one were managed by operative intervention which consisted of simple evacuation of the haematoma and closure of the serosal incision in two out of eight children. Six out of eight children operated on were followed up for 15 years, during which they were free of symptoms. Hypotonic duodenography performed in the above patients was negative for deformity or stricture of the duodenum. 相似文献
12.
We report a case of sperm cell seminoma caused by trauma. The data in the literature indicate the frequency is less than 5% of all seminomas. This case was exclusively located in the gonads and was a pure form. Orchidectomy with high ligature of the cord and adjuvant radiotherapy at the dose of 25 Gy centered on the para-aortic and subdiaphragmatic chains is adequate treatment. When inguinoscrotal surgery is performed, this zone must be irradiated with 25 Gy. Prognosis is satisfactory: 5-year survival is 100% with this protocol. 相似文献
13.
Counting Objects 总被引:1,自引:0,他引:1
14.
15.
JA Skinner G Prabhakar DG Genecov K Granke DE McDowell 《Canadian Metallurgical Quarterly》1997,90(10):993-996
BACKGROUND: Spontaneous rupture of abdominal aortic aneurysm into the inferior vena cava is rare. The clinical presentation is highly variable, and the diagnosis can be difficult, often being made only at operation. The aortocaval fistula results in a large left-to-right shunt, which can cause cardiac failure. Once the diagnosis is made, treatment is by surgical closure of the fistula and repair of the aneurysm with a graft. METHODS: This is a retrospective review of a single surgeon's experience with aortocaval fistula complicating abdominal aortic aneurysms. RESULTS: Over a 15-year period, we had five patients with spontaneous aortocaval fistula who were treated operatively. Preoperative diagnosis was made in two, suspected in one, and not made in two, one of whom died (the only perioperative death in the series). CONCLUSIONS: Spontaneous aortocaval fistulas are uncommon, and their preoperative recognition is difficult. Hematuria in association with an abdominal aortic aneurysm should raise the suspicion of an aortocaval fistula. Surgical correction is possible, with survival rates comparable to those associated with rupture of aneurysms into the retroperitoneum. Early operative control of the fistula is important to optimize the preload to the heart. 相似文献
16.
17.
HL Hinds CT Ashley JS Sutcliffe DL Nelson ST Warren DE Housman M Schalling 《Canadian Metallurgical Quarterly》1993,3(1):36-43
Prostaglandin E2 levels in isolated rat islets were increased from 64 +/- 11 pg/30 islets when incubated in medium containing 2 mM glucose to 115 +/- 9 pg/30 islets in medium containing 20 mM glucose. In contrast, glyceraldehyde (10 mM) reduced prostaglandin E2 levels to 29 +/- 6 pg/30 islets. Inhibition of glucose metabolism by mannoheptulose (10 mM) abolished the stimulatory effect of glucose on prostaglandin E2 levels and inhibited glucose-induced insulin release. The cyclooxygenase inhibitor, flurbiprofen (20 microM), did not affect insulin release caused by glucose or glyceraldehyde. In the presence of 1 mg/ml bovine serum albumin, insulin secretion induced by 20 mM glucose (6.9 +/- 1.1% of islet insulin content) was reduced by the lipoxygenase inhibitor BW755 C (20 microM) to 3.1 +/- 0.6%, and by the phospholipase A2 inhibitor, p-bromophenacyl bromide (10 microM), to 2.1 +/- 0.8%. In the absence of bovine serum albumin the inhibitory action of BW755 C and p-bromophenacyl bromide on glucose-induced insulin release was significantly more pronounced. These drugs whether in the presence or absence of bovine serum albumin, did not affect glyceraldehyde-stimulated insulin secretion. Glyceraldehyde (10 mM), potentiated glucose-induced insulin release in the presence of 2-8 mM glucose, but not for 10-20 mM glucose. Although the phospholipase A2 activator, melittin, initiated insulin release in the presence of 2 mM glucose and enhanced 10 mM glyceraldehyde-stimulated insulin secretion it had no effect on 20 mM glucose-induced insulin release. These two stimulatory effects of melittin on insulin release were totally abolished by p-bromophenacyl bromide.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
18.
Although stereotyped behavior in adult rats is partly regulated by dopamine (DA) D2 autoreceptors, previous attempts to demonstrate D2 autoreceptor regulation of stereotypy in developing rats have been unsuccessful. In the present study, two highly selective D2 autoreceptor agonists were used to demonstrate D2 autoreceptor regulation of spontaneous stereotyped behavior in developing rats. Both SND 919 and PD 128483 produced significant dose-dependent decreases in the stereotypy counts of 21-day-old, 35-day-old, and adult rats. There was a 51% decrease in the stereotypy counts of 21-day-old rats injected with SND 919, 0.05 mg/kg, compared to a 36% decrease in the counts of rats pretreated with haloperidol. Similarly, PD 128483 significantly decreased the stereotypy counts of 21-, 35-day-old, and adult rats in a dose-dependent fashion. There was a 58% decrease in the stereotypy counts of 21-day-old rats injected with PD 128483, 0.1 mg/kg, compared to a 17% decrease in counts when the rats were first treated with haloperidol. The effect of haloperidol plus PD 128483 was significantly different from the effect of PD 128483 alone. Injection of SND 919 or PD 128483 had no significant effects on the stereotypy counts of 10-day-old rats. The results suggest that DA D2 autoreceptor-mediated regulation of spontaneous stereotyped behavior is functional at 21, but not 10, days of age. 相似文献
19.
The paper deals with methods facilitating the preparation of oncospheres of the cestode, Hymenolepis diminuta, for experimental studies. Described in detail are procedures for the infection of the definitive hosts with the oncospheres; collection and artificial hatching of oncospheres; purification of hexacanths; preparation of extracts from the hexacanths; and preparation of hexacanths for electronmicroscopic studies. 相似文献
20.
RAFAEL DÍAZ-SOBAC ALMA VAZQUEZ LUNA CÉSAR I. BERISTAIN JAVIER DE LA CRUZ HUGO SERGIO GARCIA 《Journal of Food Processing and Preservation》1996,20(3):191-202
A coating emulsion was prepared using maltodextrins, carboxymethylcellulose, propileneglycol and a mixture of s orbit an fatty acid esters with an HLB of 6. The emulsion was sprayed on fully mature, unripened manila mangoes, which were the stored at 15 and 25C and 80–85% R.H. At 25C it was observed that rate CO2 production increased and lost in control fruits after 12 days of storage. Coated mangoes kept their rate CO2 production and suffered only 8% weight loss after 21 days of storage. After storage, the coating was washed out and fruits were allowed to ripen naturally, which occurred in 3–4 days. The results obtained from this study indicate that application of the hydrophobic coating extended the postharvest storage of mangoes for at least 20 days more than uncoated fruits. 相似文献