全文获取类型
收费全文 | 21601篇 |
免费 | 849篇 |
国内免费 | 318篇 |
专业分类
电工技术 | 474篇 |
综合类 | 546篇 |
化学工业 | 3863篇 |
金属工艺 | 521篇 |
机械仪表 | 737篇 |
建筑科学 | 903篇 |
矿业工程 | 183篇 |
能源动力 | 573篇 |
轻工业 | 2316篇 |
水利工程 | 251篇 |
石油天然气 | 178篇 |
武器工业 | 27篇 |
无线电 | 2407篇 |
一般工业技术 | 2858篇 |
冶金工业 | 3857篇 |
原子能技术 | 169篇 |
自动化技术 | 2905篇 |
出版年
2023年 | 119篇 |
2022年 | 354篇 |
2021年 | 494篇 |
2020年 | 266篇 |
2019年 | 346篇 |
2018年 | 395篇 |
2017年 | 367篇 |
2016年 | 420篇 |
2015年 | 365篇 |
2014年 | 556篇 |
2013年 | 1043篇 |
2012年 | 829篇 |
2011年 | 1017篇 |
2010年 | 779篇 |
2009年 | 852篇 |
2008年 | 838篇 |
2007年 | 845篇 |
2006年 | 739篇 |
2005年 | 637篇 |
2004年 | 705篇 |
2003年 | 917篇 |
2002年 | 1212篇 |
2001年 | 1023篇 |
2000年 | 601篇 |
1999年 | 551篇 |
1998年 | 1387篇 |
1997年 | 913篇 |
1996年 | 654篇 |
1995年 | 446篇 |
1994年 | 332篇 |
1993年 | 366篇 |
1992年 | 197篇 |
1991年 | 157篇 |
1990年 | 153篇 |
1989年 | 138篇 |
1988年 | 136篇 |
1987年 | 114篇 |
1986年 | 115篇 |
1985年 | 156篇 |
1984年 | 89篇 |
1983年 | 91篇 |
1982年 | 85篇 |
1981年 | 103篇 |
1980年 | 99篇 |
1979年 | 61篇 |
1978年 | 54篇 |
1977年 | 107篇 |
1976年 | 203篇 |
1975年 | 52篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The influence of ointment formulation on the stability, the in-vitro release and the in-vivo absorption through the skin of rabbits was investigated. The choice of the selected ointments has no influence on the drug stability with the exception of an acidified emulsion base. A good correlation between in-vitro release and in-vivo absorption was found revealing that metronidazole was quickly released and effectively absorbed from a polyethylene glycol base. 相似文献
62.
M. L. Rojas-Cervantes A. J. Lopez-Peinado J. De D. Lopez-Gonzalez F. CarrascO-Marin 《Journal of Materials Science》1996,31(2):437-444
Some zirconia-supported vanadium oxides have been prepared by sol-gel method and characterized by different techniques. The vanadium content exerts an effect on the area and pore-size of precursors and samples calcined. The presence of vanadium also affects the decomposition of precursors into ZrO2 and to its phase transformation, as well as the formation of fibres, as shown by SEM-EDX. XPS analyses show the presence of two species of vanadium at the surface, V5– and V4+, the percentage of each one depending on the load of vanadium in the catalyst. 相似文献
63.
P Cappelaere B Hecquet F Rolland L Meeus C Domenge I Krakowski C De Gislain J Chauvergne F Dufour-Esquerré P Carde 《Canadian Metallurgical Quarterly》1995,82(9):732-737
Eighty-four patients with locally advanced, non metastatic squamous cell carcinoma of head and neck or esophagus, were included in a multicentric double-blind randomized trial, comparing goralatide (12.5 or 62.5 micrograms/kg/day, d1-d4) to placebo, associated with carboplatin (400 mg/m2, d1) and 5-fluorouracile (1 g/m2/d continuous IV over 96 hours). Haematological toxicity was analysed on 221 cycles of chemotherapy. All but one patient were evaluable because of early death without haematological toxicity. No significant difference was observed for mean nadir of leukocytes, granulocytes, platelets counts and hemoglobin level. Duration of haematological toxicity was no significantly different for the two groups of patients. Anemia and lymphopenia were more frequent in the goralatide treated patients. Clinical and biological tolerability of goralatide was excellent. 相似文献
64.
B Annibale L De Magistris V Corleto G D'Ambra M Marignani C Iannoni G Delle Fave 《Canadian Metallurgical Quarterly》1994,8(1):87-93
We measured basal and pentagastrin-stimulated acid secretion, as well as basal and meal-stimulated plasma gastrin concentration to determine, in 67 patients affected by resistant duodenal ulcer, whether their condition could be related to gastric acid secretion and/or gastrin-related syndromes. We then compared them to 46 duodenal ulcer control patients. The outpatients were investigated consecutively. The resistant duodenal ulcer patients differed from the controls only in their higher complication rates (bleeding or perforation, P < 0.05). We identified five patients in the resistant duodenal ulcer group with Zollinger-Ellison syndrome and 12 with antral G cell hyperfunction, whereas in the control group only one patient was affected by antral G cell hyperfunction. IgG anti-Helicobacter pylori antibodies were positive for the presence of infection in 7 of the hypergastrinaemic patients. When Zollinger-Ellison syndrome or antral G cell hyperfunction were excluded, no differences could be found in gastric acid secretion, or basal and meal-stimulated plasma gastrin levels, between the resistant and control duodenal ulcer patients, except for basal acid hypersecretion (resistant duodenal ulcer 16% vs duodenal ulcer 2% P = 0.0144). In the presence of duodenal ulcer disease resistant to H2-blockers, it is mandatory to measure basal plasma gastrin concentration since it was possible to diagnose the gastrin-related syndromes, Zollinger-Ellison syndrome and antral G cell hyperfunction, in 26% of this group of patients. 相似文献
65.
H Thormar G Georgsson PA Pálsson J Balzarini L Naesens S Torsteinsdóttir E De Clercq 《Canadian Metallurgical Quarterly》1995,92(8):3283-3287
The acyclic nucleoside phosphonate analog 9-(2-phosphonylmethoxyethyl)adenine (PMEA) was recently found to be effective as an inhibitor of visna virus replication and cytopathic effect in sheep choroid plexus cultures. To study whether PMEA also affects visna virus infection in sheep, two groups of four lambs each were inoculated intracerebrally with 10(6.3) TCID50 of visna virus strain KV1772 and treated subcutaneously three times a week with PMEA at 10 and 25 mg/kg, respectively. The treatment was begun on the day of virus inoculation and continued for 6 weeks. A group of four lambs were infected in the same way but were not treated. The lambs were bled weekly or biweekly and the leukocytes were tested for virus. At 7 weeks after infection, the animals were sacrificed, and cerebrospinal fluid (CSF) and samples of tissue from various areas of the brain and from lungs, spleen, and lymph nodes were collected for isolation of virus and for histopathologic examination. The PMEA treatment had a striking effect on visna virus infection, which was similar for both doses of the drug. Thus, the frequency of virus isolations was much lower in PMEA-treated than in untreated lambs. The difference was particularly pronounced in the blood, CSF, and brain tissue. Furthermore, CSF cell counts were much lower and inflammatory lesions in the brain were much less severe in the treated lambs than in the untreated controls. The results indicate that PMEA inhibits the propagation and spread of visna virus in infected lambs and prevents brain lesions, at least during early infection. The drug caused no noticeable side effects during the 6 weeks of treatment. 相似文献
66.
67.
Mei Xuan Xu Wen Guang Liu Yun Lin Guan Zuo Peng Bi Kang De Yao 《Polymer International》1995,38(2):205-209
The phase behavior of a hybrid polymer network (HPN) composed of poly[(propylene glycol maleate)-co-(propylene glycol phthalate)] crosslinked with styrene and polyester–urethane crosslinked with methylene-bis-ortho-chloroaniline was examined. The correlation between phase separation and impact strength of the HPNs is discussed. The composition of HPNs has an effect on their properties. 相似文献
68.
Probabilistic Visual Cryptography Schemes 总被引:1,自引:0,他引:1
69.
70.