首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   387篇
  免费   31篇
电工技术   2篇
化学工业   91篇
金属工艺   6篇
机械仪表   6篇
建筑科学   9篇
能源动力   23篇
轻工业   66篇
水利工程   3篇
无线电   22篇
一般工业技术   57篇
冶金工业   89篇
原子能技术   3篇
自动化技术   41篇
  2023年   4篇
  2022年   1篇
  2021年   29篇
  2020年   16篇
  2019年   6篇
  2018年   16篇
  2017年   16篇
  2016年   18篇
  2015年   17篇
  2014年   10篇
  2013年   22篇
  2012年   20篇
  2011年   31篇
  2010年   16篇
  2009年   13篇
  2008年   12篇
  2007年   11篇
  2006年   12篇
  2005年   7篇
  2004年   5篇
  2003年   7篇
  2002年   3篇
  2001年   3篇
  2000年   4篇
  1999年   7篇
  1998年   21篇
  1997年   14篇
  1996年   16篇
  1995年   6篇
  1994年   7篇
  1993年   8篇
  1991年   2篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1975年   4篇
  1974年   2篇
  1973年   3篇
  1968年   1篇
  1964年   1篇
排序方式: 共有418条查询结果,搜索用时 812 毫秒
1.
Mosquito-borne Zika virus (ZIKV) became a real threat to human health due to the lack of vaccine and effective antiviral treatment. The virus has recently been responsible for a global outbreak leading to millions of infected cases. ZIKV complications were highlighted in adults with Guillain–Barré syndrome and in newborns with increasing numbers of congenital disorders ranging from mild developmental delays to fatal conditions. The ability of ZIKV to establish a long-term infection in diverse organs including the kidneys has been recently documented but the consequences of such a viral infection are still debated. Our study aimed to determine whether the efficiency of ZIKV growth in kidney cells relates to glucose concentration. Human kidney HK-2 cells were infected with different ZIKV strains in presence of normal and high glucose concentrations. Virological assays showed a decrease in viral replication without modifying entry steps (viral binding, internalization, fusion) under high glucose conditions. This decrease replication was associated with a lower virus progeny and increased cell viability when compared to ZIKV-infected HK-2 cells in normal glucose concentration. In conclusion, we showed for the first time that an elevated glucose level influences ZIKV replication level with an effect on kidney cell survival.  相似文献   
2.
We aimed to compare detailed fat distribution and lipid profile between young adults with congenital adrenal hyperplasia due to 21-hydroxylase enzyme deficiency and a control group. We also verified independent associations of treatment duration and daily hydrocortisone dose equivalent (HDE) with lipid profile within patients. This case–control study included 23 patients (7 male and 16 female) matched by an age range of young adults (18–31 years) with 20 control subjects (8 male and 12 female). Dual energy X-ray absorptiometry was used to measure the fat distribution. Male patients demonstrated elevated indices of fat mass for total (7.7 ± 2.1 vs. 4.5 ± 1.3 kg/m2, p = 0.003), trunk (4.0 ± 1.2 vs. 2.2 ± 0.8 kg/m2, p = 0.005), android (0.63 ± 0.24 vs. 0.32 ± 0.15 kg/m2, p = 0.008), gynoid (1.34 ± 0.43 vs. 0.74 ± 0.24 kg/m2, p = 0.005), arm (0.65 ± 0.16 vs. 0.39 ± 0.10 kg/m2, p = 0.009), and leg regions (2.7 ± 0.8 vs. 1.6 ± 0.4 kg/m2, p = 0.005) than the control group, but not in females. However, female patients demonstrated elevated ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (1.90 ± 0.46 vs. 1.39 ± 0.47, p = 0.009) than the control group, but not in males. Total fat mass was inversely correlated with total testosterone (r = −0.64, p = 0.014) and positively correlated with leptin in males (r = 0.75, p = 0.002). An elevated daily HDE (β = 0.43, p = 0.038 and β = 0.47, p = 0.033) and trunk to total fat mass ratio (β = 0.46, p = 0.025, and β = 0.45, p = 0.037) were independently correlated with impaired lipid profile markers. Although there is no altered lipid profile, male patients demonstrated an increased fat distribution. However, female patients presented with an impaired lipid profile marker but demonstrated close values of normal fat distribution. Interestingly, the dose of glucocorticoid therapy can have some role in the lipid mechanisms.  相似文献   
3.
A discontinuous borate/formate buffer system is presented for horizontal polyacrylamide gel electrophoresis of DNA fragments. The resolution potential of the system could be altered by changing the total monomer concentration (5-9%T), the concentration of the crosslinker piperazine diacrylamide (2-5%CPDA), as well as the concentration of formate in the gel (40-120 mM), the leading ion of the buffer system. The separation of DNA fragments would be improved by increasing the migration distance from 22 to 28 cm. This discontinuous polyacrylamide gel electrophoresis system proved highly reproducible.  相似文献   
4.
L. Marini  R. Cioni 《Geothermics》1985,14(1):29-34
Chloride concentrations and pressures (or temperatures) in two points of a geothermal test line have been used to determine the enthalpy of the steam/water mixture discharged from Nisyros I geothermal well (Greece). The results are in agreement with those obtained by the Russell James method. The chloride method described in this paper is fast, requires cheap, portable equipment and is thus particularly suitable for short-term well testing during drilling or immediately after well completion, especially in steam-rich mixtures.  相似文献   
5.
6.
The antifeedant activity of a series of 21 chalcones, flavanes, and flavanones isolated from the generaLonchocarpus andTephrosia (Leguminosae) was assessed by behavioral and electrophysiological bioassays against larvae ofSpodoptera littoralis andS. exempta. The antifeedant activity is related to the molecular structure of the compounds, and possible modes of interaction with the insect taste receptors are discussed.  相似文献   
7.
The prediction of wheel and rail wear is a fundamental issue in the railway field, both in terms of vehicle stability and in terms of economic costs (planning of maintenance interventions). In particular the need of an accurate wear model arises from the interest of Trenitalia S.p.A. and Rete Ferroviara Italiana in designing new wheel and rail profiles and new bogie architectures optimized from the wear viewpoint with the aim of improving the wear and stability behavior of the standard ORE S1002 wheel profile matched with the UIC60 rail profile canted at 1/20 rad (which represents the wheel–rail combination adopted by the Italian railway line). In this work the authors present a wear model specifically developed for the evaluation of the wheel and rail profile evolution, the layout of which is made up of two mutually interactive but separate units: a vehicle model for the dynamical analysis and a model for the wear evaluation. Subsequently the new model has been compared with the wear evaluation procedure implemented in Simpack, a widely tested and validated multibody software for the analysis of the railway vehicle dynamics; the comparison aims both to evaluate the model performance (in terms of accuracy and efficiency) and to further validate the wear model (just tested, as regards the wheel wear prediction, in previous works related to the critical Aosta–Pre Saint Didier line). The comparison has been carried out considering a benchmark train composed by a locomotive (E.464) and a passenger vehicle (Vivalto) provided by Trenitalia while the simulations have been performed on a mean Italian railway line (obtained by means of a statistical analysis of the data relative to the whole Italian railway network provided by Rete Ferroviaria Italiana (RFI)).  相似文献   
8.
Stereoscopic displays are becoming popular in entertainment and industrial applications. We characterize the spatial resolution and noise properties of a stereoscopic display with a half‐mirror and passive polarizing glasses. The upper display images reflected off the mirror have slightly degraded sharpness and reduced high spatial‐frequency noise resulting in modulation transfer functions (MTFs) of 0.59 and 0.50 at the Nyquist frequency with corresponding noise power spectra (NPS) values of 4.79 × 10?6 and 5.17 × 10?6 mm2 at 10 mm?1 in the horizontal and vertical directions. These results are compared to the characteristics of the individual displays with MTF values of 0.64 and 0.53 and NPS values of 6.24 × 10?6 and 5.87 × 10?6 mm2. The polarizing glasses cause minimal reduction in sharpness and high‐frequency noise. The MTFs in the upper images observed with glasses are decreased to 0.54 and 0.47, while the NPS are decreased to 2.86 × 10?6 and 2.01 × 10?6 mm2. When both displays are turned on and using the mirror and glasses, the observed luminance for each eye is increased from the luminance of the individual displays owing to crosstalk. We find that sharpness and noise are not affected by the interaction between the displays at the particular geometry tested in this study.  相似文献   
9.
The complexity of constraints is a major obstacle for constraint-based software verification. Automatic constraint solvers are fundamentally incomplete: input constraints often build on some undecidable theory or some theory the solver does not support. This paper proposes and evaluates several randomized solvers to address this issue. We compared the effectiveness of a symbolic solver (CVC3), a random solver, two heuristic search solvers, and seven hybrid solvers (i.e. mix of random, symbolic, and heuristic solvers). We evaluated the solvers on a benchmark generated with a concolic execution of 9 subjects. The performance of each solver was measured by its precision, which is the fraction of constraints that the solver can find solution out of the total number of constraints that some solver can find solution. As expected, symbolic solving subsumes the other approaches for the 4 subjects that only generate decidable constraints. For the remaining 5 subjects, which contain undecidable constraints, the hybrid solvers achieved the highest precision (fraction of constraints that a solver can find a solution out of the total number of satisfiable constraints). We also observed that the solvers were complementary, which suggests that one should alternate their use in iterations of a concolic execution driver.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号