全文获取类型
收费全文 | 861篇 |
免费 | 14篇 |
专业分类
电工技术 | 57篇 |
化学工业 | 114篇 |
金属工艺 | 20篇 |
机械仪表 | 8篇 |
建筑科学 | 24篇 |
能源动力 | 13篇 |
轻工业 | 45篇 |
石油天然气 | 1篇 |
无线电 | 160篇 |
一般工业技术 | 142篇 |
冶金工业 | 208篇 |
原子能技术 | 36篇 |
自动化技术 | 47篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 25篇 |
2012年 | 20篇 |
2011年 | 24篇 |
2010年 | 26篇 |
2009年 | 22篇 |
2008年 | 18篇 |
2007年 | 35篇 |
2006年 | 23篇 |
2005年 | 27篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 21篇 |
2000年 | 11篇 |
1999年 | 28篇 |
1998年 | 85篇 |
1997年 | 55篇 |
1996年 | 45篇 |
1995年 | 28篇 |
1994年 | 31篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有875条查询结果,搜索用时 15 毫秒
851.
I Takada 《Canadian Metallurgical Quarterly》1976,4(5):471-478
Since Westerburg (1966) reported a case of hypertensive intracerebral hemorrhage who showed extravasation of contrast media on the cerebral angiogram, only 21 cases demonstrated extravasation of contrast media were reported by several authors. The author experienced 14 cases of hypertensive intracerebral hemorrhage whose cerebral angiogram showed extravasation of contrast media. These 14 cases occupied 21.1% of 58 cases whom cerebral angiographies were performed within 24 hours after the stroke. 6 out of 14 cases were cured by evacuation of the hematoma surgically. These 14 cases were dividied into three types by the shape of extravasation of contrast media as followed: Type I showed widespread leakage of contrast media. Type II showed sash-like leakage of contrast media surrounded by diffuse thin shadow and Type III showed small spotlike leakage of contrast media. These three types indicated the arterial bleeding stage, the stage of accerelated arterial wall permeability and the subsquent venous bleeding respectively. The author concluded that these extravasation of contrast media not only demonstrated the bleeding artery but also indicated the process of the hematoma formation in each case. 相似文献
852.
We recently reported that picomolar doses of norethindrone (NET), a synthetic analog of 19-nortestosterone, significantly stimulated human TE85 osteosarcoma cell proliferation, differentiation, and activity in vitro. In the present study, we investigated the possibility that NET interacts with another osteogenic agent, i.e., fluoride, to stimulate human TE85 osteosarcoma cell proliferation, differentiation, and activities. Bone cell proliferation was measured by the stimulation in [3H]thymidine incorporation. Differentiation was monitored by the increase in alkaline phosphatase-specific activity. Osteoblastic activity was assessed by the stimulations in collagen synthesis and in osteocalcin secretion (in the presence of 1 nM 1,25-dihydroxyvitamin D3). When the human TE85 cells were incubated with mitogenic doses of NET and fluoride concurrently, the stimulatory effects of the two agents on these parameters exhibited no significant interaction. The enhancing effect of NET on the osteogenic effect of fluoride was not due to a shift of the fluoride dose response curve. Pretreatment with NET for 24 h followed by a treatment with a mitogenic dose (i.e., 100 microM) of fluoride for an additional 24 h significantly and synergistically potentiated the effects of fluoride on the [3H]thymidine incorporation, alkaline phosphatase-specific activity, collagen synthesis, and osteocalcin secretion, compared with those with the subsequent vehicle (0.05% ethanol) treatments. In contrast, pretreatment with fluoride for 24 h before the addition of NET for 24 h did not produce significant synergistic stimulations in the test parameters. Pretreatment of TE85 cells with the same doses of dihydrotestosterone or progesterone prior to treatment with fluoride under the same conditions did not induce synergistic potentiation of fluoride in [3H]thymidine incorporation, suggesting that the synergistic interaction with fluoride is probably not a common property of anabolic sex steroids. In summary, we found that: (1) the osteogenic effects of fluoride and NET were additive when cells were treated with both agents concurrently; (2) a 24-h pretreatment with picomolar doses of NET potentiated the osteogenic actions of fluoride in human TE85 osteosarcoma cells; and (3) pretreatment with NET produced a subsequent fluoride response that was synergistic. In conclusion, these findings led us to speculate that the osteogenic actions of NET and fluoride act through different mechanisms, and that NET at low doses has a permissive effect on the osteogenic effects of fluoride, and as such NET may be used in concert with fluoride to increase osteoblast proliferation, differentiation, and activity. 相似文献
853.
854.
A 1 GHz dual modulus 128/129 prescaler with only a 5 mA dissipation current is developed. A 5-level series gating source-coupled FET logic is used to attain this small current. The IC is fabricated with 0.5 ?m-gate-length GaAs MESFETs. This prescaler is suitable for a synthesiser in a mobile communication system. 相似文献
855.
856.
An improved process for the mass production of D-psicose from D-fructose was developed. A D-fructose solution (60%, pH 7.0) was passed at 45 degrees C through a column filled with immobilized D-tagatose 3-epimerase (D-TE) which was produced using recombinant Escherichia coli, and 25% of the substrate was converted to D-psicose. After epimerization, the substrate, D-fructose, was removed by treatment with baker's yeast. The supernatant was concentrated to a syrup by evaporation under vacuum and D-psicose was crystallized with ethanol. Approximately 20 kg of pure crystal D-psicose was obtained in 60 d. 相似文献
857.
Menavuvu BT Poonperm W Takeda K Morimoto K Granström TB Takada G Izumori K 《Journal of Bioscience and Bioengineering》2006,102(5):436-441
d-Arabinose isomerase from Klebsiella pneumoniae 40bXX was purified 12-fold with a 62.5% yield indicated by its electrophoretic homogeneity. The purified enzyme showed the highest activities toward d-arabinose and l-fucose as substrates at optimum conditions (50 mM glycine-NaOH, pH 9.0, 40 degrees C). The enzyme had a broad range of substrate specificities toward various d/l-aldoses, i.e., d-arabinose, l-fucose, d/l-xylose, d-mannose, d/l-lyxose, l-glucose, d-altrose and d/l-galactose. The equilibrium ratios between d-arabinose and d-ribulose, l-fucose and l-fuculose, d-altrose and d-psicose, and l-galactose and l-tagatose were 90:10, 90:10, 13:87 and 25:75, respectively. Using a combination of the immobilized d-tagatose 3-epimerase and d-arabinose isomerase, we achieved the production of d-altrose from d-fructose in a batch reactor. We successfully produced approximately 12 g of d-altrose from 200 g of d-fructose in a reaction series with an overall yield of 6%. The product obtained was confirmed to be d-altrose by HPLC and (13)C-NMR. To the best of our knowledge, this is the first report on the production of d-altrose from a cheap sugar, d-fructose, using an enzymatic method. 相似文献
858.
Asian Mussel Watch Program: contamination status of polybrominated diphenyl ethers and organochlorines in coastal waters of Asian countries 总被引:3,自引:0,他引:3
Ramu K Kajiwara N Sudaryanto A Isobe T Takahashi S Subramanian A Ueno D Zheng GJ Lam PK Takada H Zakaria MP Viet PH Prudente M Tana TS Tanabe S 《Environmental science & technology》2007,41(13):4580-4586
Mussel samples were used in this study to measure the levels of polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs) in the coastal waters of Asian countries like Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, the Philippines, and Vietnam. PBDEs were detected in all the samples analyzed, and the concentrations ranged from 0.66 to 440 ng/g lipid wt. Apparently higher concentrations of PBDEs were found in mussels from the coastal waters of Korea, Hong Kong, China, and the Philippines, which suggests that significant sources of these chemicals exist in and around this region. With regard to the composition of PBDE congeners, BDE-47, BDE-99, and BDE-100 were the dominant congeners in most of the samples. Among the OCs analyzed, concentrations of DDTs were the highest followed by PCBs > CHLs > HCHs > HCB. Total concentrations of DDTs, PCBs, CHLs, and HCHs in mussel samples ranged from 21 to 58 000, 3.8 to 2000, 0.93 to 900, and 0.90 to 230 ng/g lipid wt., respectively. High levels of DDTs were found in mussels from Hong Kong, Vietnam, and China; PCBs were found in Japan, Hong Kong, and industrialized/urbanized locations in Korea, Indonesia, the Philippines, and India; CHLs were found in Japan and Hong Kong; HCHs were found in India and China. These countries seem to play a role as probable emission sources of corresponding contaminants in Asia and, in turn, may influence their global distribution. 相似文献
859.
Managaki S Murata A Takada H Tuyen BC Chiem NH 《Environmental science & technology》2007,41(23):8004-8010
We investigated the distributions of 12 antibiotics (viz., sulfonamides, macrolides, and trimethoprim) in the water from the Mekong Delta, Vietnam, and compared them with those in the Tamagawa River, Japan. In Vietnam, only a few antibiotics (viz., sulfamethoxazole, sulfamethazine, trimethoprim, and erythromycin-H2O) were detected in the river and canals from urban and rural sites, at concentrations of 7-360 ng/L. This contrasts with the results from the Japanese urban river, where more antibiotics (sulfamethoxazole, sulfapyridine, trimethoprim, erythromycin-H20, azithromycin, clarithromycin, and roxithromycin) were detected at concentrations ranging from 4to 448 ng/L. The concentrations of sulfonamides in the Mekong Delta were comparable to those in the Tamagawa River, whereas macrolide concentrations were lowerthanthose in the Tamagawa River. The ubiquitous occurrence of sulfamethazine, used as a veterinary medicine, in the waters in Vietnam at relatively high concentrations (15-328 ng/L) was unique. Extremely high concentrations of sulfamethazine [(18.5-19.2) x 10(3) ng/L] were detected in pig farm wastewaters, and relatively high concentrations were observed in canals near chicken and pig farms. All these data suggested the potential utility of sulfamethazine as a molecular marker of livestock-source contamination. The present study demonstrated widespread inputs of veterinary medicines to waters in Vietnam. 相似文献
860.
Yasutami Takada 《Journal of Superconductivity and Novel Magnetism》2009,22(1):89-92
On the basis of the model that was successfully applied to KC8, RbC8, and CsC8 about a quarter century ago, we have implemented a quantitative calculation of the superconducting transition temperature T c to find that the observed values for T c in both CaC6 and YbC6 are also reproduced in the model, indicating that the model is a unified one for superconductivity in the graphite intercalation compounds with T c ranging three orders of magnitudes. 相似文献