全文获取类型
收费全文 | 2146篇 |
免费 | 34篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 3篇 |
综合类 | 4篇 |
化学工业 | 58篇 |
金属工艺 | 15篇 |
机械仪表 | 6篇 |
建筑科学 | 5篇 |
矿业工程 | 4篇 |
能源动力 | 5篇 |
轻工业 | 14篇 |
水利工程 | 25篇 |
无线电 | 24篇 |
一般工业技术 | 42篇 |
冶金工业 | 1937篇 |
原子能技术 | 2篇 |
自动化技术 | 40篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 18篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 2篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 22篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 4篇 |
1999年 | 62篇 |
1998年 | 627篇 |
1997年 | 382篇 |
1996年 | 226篇 |
1995年 | 110篇 |
1994年 | 92篇 |
1993年 | 105篇 |
1992年 | 16篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 32篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1978年 | 3篇 |
1977年 | 44篇 |
1976年 | 101篇 |
1975年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1962年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有2184条查询结果,搜索用时 0 毫秒
71.
72.
73.
Sixteen consecutive patients with cutout of a lag screw of a dynamic hip screw fixation in an intertrochanteric fracture were treated with reinsertion of a lag screw, bone cement supplementation in the neck-trochanter, and subtrochanteric valgus osteotomy. Postoperatively, patients were permitted to ambulate with protected weight-bearing. Fourteen patients were followed-up for at least 1 year (median 2 years; range 1-3 years), and all had a solid union. The union period took a median of 5 months, with a range of 3-7 months. Usually, union of an intertrochanteric fracture was faster than that of subtrochanteric osteotomy (P < 0.01). There were no complications of wound infection, loss of reduction, cutout of a lag screw, or osteonecrosis of the femoral head. From clinical and theoretical considerations, we conclude that despite cutout of a lag screw of a dynamic hip screw fixation being difficult to treat, out technique still can provide an excellent outcome. Therefore, we strongly recommend its wide use. 相似文献
74.
D Ili? EA Almeida DD Schlaepfer P Dazin S Aizawa CH Damsky 《Canadian Metallurgical Quarterly》1998,143(2):547-560
In many malignant cells, both the anchorage requirement for survival and the function of the p53 tumor suppressor gene are subverted. These effects are consistent with the hypothesis that survival signals from extracellular matrix (ECM) suppress a p53-regulated cell death pathway. We report that survival signals from fibronectin are transduced by the focal adhesion kinase (FAK). If FAK or the correct ECM is absent, cells enter apoptosis through a p53-dependent pathway activated by protein kinase C lambda/iota and cytosolic phospholipase A2. This pathway is suppressible by dominant-negative p53 and Bcl2 but not CrmA. Upon inactivation of p53, cells survive even if they lack matrix signals or FAK. This is the first report that p53 monitors survival signals from ECM/FAK in anchorage- dependent cells. 相似文献
75.
M Sawada CH Park H Kondo T Morita A Shimada I Yamane T Umemura 《Canadian Metallurgical Quarterly》1998,60(7):853-854
Prevalence of antibody to Neospora caninum (NC) in Japanese dogs were examined. The antibody was positive in 15 of 48 dogs (31.3%) reared in the dairy farms that had case of the abortions due to NC infection or had the cattle seropositive to NC, whereas the prevalence was 7.1% (14 of 198 dogs) among the dogs kept in urban areas. In one dog breeder, all 17 Shetland sheepdogs older than 7 months were seropositive, and one pup was diagnosed as neosporosis 2 months before the first serological examination. The antibody titers of the dogs kept at this breeder were almost unchanged for 1.5 years. Serological evidence of the dogs in the dairy farms and urban areas indicates the transmission of NC between dogs and cattle. Also serological results of the dogs in one breeder may suggest the potential horizontal transmission among dogs. 相似文献
76.
Giant-cell interstitial Pneumonia (GIP) is a very uncommon respiratory disease. The majority of cases of GIP are caused by exposure to cobalt, tungsten and other hard metals. In this report, we describe GIP in a patient who worked in gas station and dealt in propane gas vessels. He presented with clinical features of chronic interstitial lung disease and underwent an open lung biopsy that showed DIP-like reaction with large numbers of intra-alveolar macrophages and numerous large, multinucleated histiocytes which were admixed with the macrophages. Analysis of lung tissue for hard metals was done. Cobalt was the main component of detected hard metals. Corticosteroid therapy was started and he recovered fully. 相似文献
77.
CH Brenner 《Canadian Metallurgical Quarterly》1998,62(6):1558-60; author reply 1560-1
78.
Iron is required for cell proliferation of all living species. Moreover, iron excess may be involved in the development of hepatocellular carcinoma. In this study we analyzed the effects of deferoxamine, an iron chelator, on normal porcine hepatocyte proliferation. We confirmed that hepatocytes isolated from young pigs proliferate in the presence of insulin and fetal calf serum as shown by [3H] methyl-thymidine incorporation, presence of mitotic figures and increase in cell number. This was paralleled by nuclear expression of p34cdc2 and its associated histone H1 kinase activity. In the presence of deferoxamine, [3H] methyl-thymidine incorporation, expression of nuclear proteins (p34cdc2 and PCNA) and H1 kinase activity were drastically reduced. In addition, in contrast with control cultures, cells in S-phase were not detected by flow cytometry. These data suggest that iron chelation by deferoxamine can arrest the progression of porcine hepatocytes in the G1 phase of the cell cycle. 相似文献
79.
80.
Exercise has a noted effect on skin blood flow and temperature. We aimed to characterize the normal skin temperature response to exercise by thermographic imaging. A study was conducted on ten healthy and active subjects (age=25.8+/-0.7 years) who were exposed to graded exercise for determination of maximal oxygen consumption (VO2 max), and subsequently to constant loads corresponding to 50%, 70%, and 90% of VO2 max. The skin temperature response during 20 min of constant load exercise is characterized by an initial descending limb, an ascending limb and a quasi-steady-state period. For 50% VO2 max, the temperature decrease rate was - 0.0075+/-0.001 degrees C/s during a time interval of 390+/-47 s and the temperature increase rate was 0.0055+/-0.0031 degrees C/s during a time interval of 484+/-99 s. The level of load did not influence the temperature decrease and increase rates. In contrast, during graded load exercise, a continuous temperature decrease of -0.0049+/-0.0032 degrees C/s was observed throughout the test. In summary, the thermographic skin response to exercise is characterized by a specific pattern which reflects the dynamic balance between hemodynamic and thermoregulatory processes. 相似文献