全文获取类型
收费全文 | 1584篇 |
免费 | 9篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 137篇 |
金属工艺 | 13篇 |
机械仪表 | 20篇 |
建筑科学 | 57篇 |
矿业工程 | 2篇 |
能源动力 | 14篇 |
轻工业 | 102篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 50篇 |
一般工业技术 | 91篇 |
冶金工业 | 1030篇 |
原子能技术 | 13篇 |
自动化技术 | 47篇 |
出版年
2021年 | 11篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 33篇 |
2012年 | 19篇 |
2011年 | 13篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 20篇 |
2007年 | 26篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 11篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 42篇 |
1998年 | 295篇 |
1997年 | 160篇 |
1996年 | 128篇 |
1995年 | 70篇 |
1994年 | 67篇 |
1993年 | 66篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 15篇 |
1983年 | 25篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 40篇 |
1976年 | 77篇 |
1975年 | 19篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1971年 | 6篇 |
1970年 | 5篇 |
排序方式: 共有1601条查询结果,搜索用时 781 毫秒
71.
72.
BG Wallin G Sundl?f BM Eriksson P Dominiak H Grobecker LE Lindblad 《Canadian Metallurgical Quarterly》1981,111(1):69-73
Recordings of multiunit sympathetic activity were made in muscle branches of the peroneal nerve in 22 healthy subjects at rest in recumbent position. Nerve activity was quantitated in terms of burst incidence (number of pulse synchronous sympathetic bursts per 100 heart beats or per min). In a separate session, 4-45 months later, blood was drawn from an antecubital vein for noradrenaline analysis. Both sympathetic activity and plasma concentrations of noradrenaline varied widely between subjects and both parameters increased with age. There was a significant positive correlation between a subject's level of sympathetic activity and his plasma concentration of noradrenaline. It is suggested that overflow of transmitter from sympathetic terminals in muscles contributes significantly to plasma levels of noradrenaline at rest. 相似文献
73.
74.
75.
We report a new application of affinity capture-elution electrospray mass spectrometry (ACESI-MS) to assay the enzymes phosphomannomutase (PMM) and phosphomannose isomerase (PMI), which when deficient cause congenital disorders of glycosylation CDG-type Ia and type Ib, respectively. The novel feature of this mass-spectrometry-based assay is that it allows one to distinguish and quantify enzymatic products that are isomeric with their substrates that are present simultaneously in complex mixtures, such as cultured human cell homogenates. This is achieved by coupled assays in which the PMM and PMI primary products are in vitro subjected to another enzymatic reaction with yeast transketolase that changes the mass of the products to be detected by mass spectrometry. The affinity purification procedure is fully automated, and the mass spectrometric analysis is multiplexed in a fashion that is suitable for high-throughput applications. 相似文献
76.
77.
78.
NK lysin is a 9-kDa polypeptide that was originally isolated from porcine intestinal tissue based on its antibacterial activity. It is produced by cytolytic lymphocytes and is cytolytic against a number of different types of tumor cells. Here we report the binding of NK lysin to lipopolysaccharide (LPS) and its anti-LPS activity. NK lysin binds to matrix-coated LPS from Escherichia coli, Pseudomonas aeruginosa, and different strains of Salmonella enterica. Lipid A and polymyxin B inhibited the binding, demonstrating a preferential interaction of NK lysin with the lipid part of LPS. Chromium-labeled lymphoma cells were lysed by NK lysin, and LPS dose-dependently inhibited the cytolysis at equimolar amounts. In the same manner, NK lysin inhibited certain LPS-stimulated effects on mouse bone marrow cells as well as LPS binding to mouse granulocytes. These results suggest that NK lysin may be a another natural LPS-binding protein from lymphocytes that may participate in the endogenous defense response associated with elevated concentrations of LPS. 相似文献
79.
Stahl's ear is a congenital malformation of the auricle, which is uncommon in non-Oriental societies. A number of different treatment modalities have been suggested, many of which yield unpredictable results. We review current treatment modalities from the English literature and describe a novel, simple surgical method of repair. First, a helical rim incision is made to expose the abnormal third crus and upper pole of the ear. The third crus is excised as a narrow wedge of cartilage and posterior skin, and the defect is closed primarily. The free third crus cartilage is then grafted onto the scaphal cartilage in an anatomically correct position to form a superior crus. The anterior skin flap is redraped and bolstered over this graft. Only a very small scar on the helical rim remains visible anteriorly. 相似文献
80.
A sequencing batch reactor (SBR) treating the effluent of a motorway service station in the south of England situated on a major tourist route was investigated. Wastewater from the kitchens, toilets and washrooms facilities was collected from the areas on each side of the motorway for treatment on-site. The SBR was designed for a population equivalent (p.e.) of 500, assuming an average flow of 100 m3/d, influent biochemical oxygen demand (BOD) of 300 mg/l, and influent suspended solids (SS) of 300 mg/l. Influent monitoring over 8 weeks revealed that the average flow was only 65 m3/d and the average influent BOD and SS were 480 mg/l and 473 mg/l respectively. This corresponded to a high sludge loading rate (F:M) of 0.42 d(-1) which accounted for poor performance. Therefore the cycle times were extended from 6 h to 7 h and effluent BOD improved from 79 to 27 mg/l. 相似文献