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   1322篇
  免费   27篇
电工技术   12篇
化学工业   134篇
金属工艺   4篇
机械仪表   17篇
建筑科学   7篇
能源动力   9篇
轻工业   44篇
石油天然气   2篇
无线电   57篇
一般工业技术   86篇
冶金工业   925篇
自动化技术   52篇
  2023年   2篇
  2022年   9篇
  2021年   8篇
  2020年   7篇
  2019年   6篇
  2018年   13篇
  2017年   25篇
  2016年   8篇
  2015年   9篇
  2014年   21篇
  2013年   23篇
  2012年   19篇
  2011年   35篇
  2010年   19篇
  2009年   15篇
  2008年   11篇
  2007年   19篇
  2006年   10篇
  2005年   16篇
  2004年   14篇
  2003年   21篇
  2002年   14篇
  2001年   5篇
  2000年   13篇
  1999年   38篇
  1998年   318篇
  1997年   168篇
  1996年   117篇
  1995年   61篇
  1994年   48篇
  1993年   51篇
  1992年   9篇
  1991年   38篇
  1990年   11篇
  1989年   16篇
  1988年   15篇
  1987年   14篇
  1986年   9篇
  1985年   15篇
  1984年   2篇
  1983年   5篇
  1982年   3篇
  1980年   7篇
  1979年   2篇
  1978年   7篇
  1977年   18篇
  1976年   28篇
  1975年   3篇
  1971年   1篇
  1969年   1篇
排序方式: 共有1349条查询结果,搜索用时 660 毫秒
41.
Research dealing with early diagnosis and efficient treatment in colon cancer to improve patient''s survival is still under investigation. Chemotherapeutic agent result in high systemic toxicity due to their non‐specific actions on DNA repair and/or cell replication. Traditional medicine such as Lycopodium clavatum (LC) has been claimed to have therapeutic potentials against cancer. The present study focuses on targeted drug delivery of cationic liposomal nanoformulated LC (CL‐LC) in colon cancer cells (HCT15) and comparing the efficacy with an anti‐colon cancer drug, 7‐ethyl‐10‐hydroxy‐camptothecin (SN38) along with its nanoformulated form (CL‐SN38). The colloidal suspension of LC was made using thin film hydration method. The drugs were characterised using ultraviolet, dynamic light scattering, scanning electron microscopy, energy, dispersive X‐ray spectroscopy. In vitro drug release showed kinetics of 49 and 89% of SN38 and LC, whereas CL‐SN38 and CL‐LC showed 73 and 74% of sustained drug release, respectively. Studies on morphological changes, cell viability, cytotoxicity, apoptosis, cancer‐associated gene expression analysis of Bcl‐2, Bax, p53 by real‐time polymerase chain reaction and western blot analysis of Bad and p53 protein were performed. Nanoformulated LC significantly inhibited growth and increased the apoptosis of colon cancer cells indicating its potential anti‐cancer activity against colon cancer cells.Inspec keywords: cancer, biological organs, cellular biophysics, drug delivery systems, drugs, nanomedicine, genetics, DNA, molecular biophysics, biochemistry, lipid bilayers, toxicology, suspensions, colloids, light scattering, X‐ray chemical analysis, solvation, enzymes, nanostructured materialsOther keywords: energy dispersive X‐ray spectroscopy, in vitro drug release, morphological changes, cell viability, cytotoxicity, apoptosis, cancer‐associated gene expression analysis, Bcl‐2, Bax, real‐time polymerase chain reaction, western blot analysis, Bad protein, p53 protein, scanning electron microscopy, dynamic light scattering, ultraviolet scattering, thin film hydration method, colloidal suspension, nanoformulated form CL‐SN38, 7‐ethyl‐10‐hydroxy‐camptothecin, anticolon cancer drug, colon cancer cells HCT15, cationic liposomal nanoformulated LC, targeted drug delivery, therapeutic potentials, Lycopodium clavatum, traditional medicines, cell replication, DNA repair, nonspecific actions, high systemic toxicity, chemotherapeutic agents, patient survival, colon cancer treatment, colon cancer diagnosis, CL‐LC, potential anticancer activity  相似文献   
42.
Proton transfer reactivity of isolated charge states of the protein hen egg-white lysozyme shows that multiple distinct conformations of this protein are stable in the gas phase. The reactivities of the 9+ and 10+ charge state ions, formed by electrospray ionization of "native" (disulfide-intact) and "denatured" (disulfide-reduced) solutions, are consistent with values calculated for ions in their crystal structure and fully denatured conformations, respectively. Charge states below 8+ of both forms, formed by proton stripping, have similar or indistinguishable reactivities, indicating that the disulfide-reduced ions fold in the gas phase to a more compact conformation.  相似文献   
43.
One of the most important processes in speech processing is gender classification. Generally gender classification is done by considering pitch as feature. In general the pitch value of female is higher than the male. In some cases, pitch value of male is higher and female is low, in that cases this classification will not obtain the exact result. By considering this drawback here proposed a gender classification method which considers three features and uses fuzzy logic and neural network to identify the given speech signal belongs to which gender. For training fuzzy logic and neural network, training dataset is generated by considering the above three features. After completion of training, a speech signal is given as input, fuzzy and neural network gives an output, for that output mean value is taken and this value gives the speech signal belongs to which gender. The result shows the performance of our method in gender classification.  相似文献   
44.
We show that existing theorem proving technology can be used effectively for mechanically verifying a family of arithmetic circuits. A theorem prover implementing: (i) a decision procedure for quantifier-free Presburger arithmetic with uninterpreted function symbols; (ii) conditional rewriting; and (iii) heuristics for carefully selecting induction schemes from terminating recursive function definitions; and (iv) well integrated with backtracking, can automatically verify number-theoretic properties of parameterized and generic adders, multipliers and division circuits. This is illustrated using our theorem prover Rewrite Rule Laboratory (RRL). To our knowledge, this is the first such demonstration of the capabilities of a theorem prover mechanizing induction. The above features of RRL are briefly discussed using illustrations from the verification of adder, multiplier and division circuits. Extensions to the prover likely to make it even more effective for hardware verification are discussed. Furthermore, it is believed that these results are scalable, and the proposed approach is likely to be effective for other arithmetic circuits as well.  相似文献   
45.
Even as more organizations are moving towards implementing Web-based B2B procurement solutions, they are unsure of the real benefits of the Web. In other words, what is the value of B2B e-procurement to an organization and how to measure this value? What factors affect this value? In this paper, we discuss an evaluation framework to determine the value of B2B e-procurement and the effect of process characteristics on the value. We use an empirical study to highlight the different value created by different procurement types. We then develop a more comprehensive economic model to capture the additional effects of demand volume and process complexity. The integration of theoretical and empirical approaches provides a strong foundation to develop and evaluate useful adoption strategies for B2B e-procurement.  相似文献   
46.
47.
A concentrated solar absorber with finned phase change materials was experimentally studied using a Scheffler type parabolic dish concentrator. The absorber's inner surface was fixed with hollow cylindrical containers filled with phase change material (PCM) for heat transfer augmentation. The absorber's selected PCM was acetanilide (Melting point of 116 °C)—the cylindrical capsules protruding into the fluid side to create turbulence and mixing and acting as fins. The absorber surface temperature was observed to be about 130–150 °C during the outdoor tests while passing fluid through the absorber. The fluid flow rate varied from 60 to 100 kg/h during the outdoor experiments. The peak energy and exergy efficiency of parabolic dish collector (PDC) at the fluid flow rate of 80 kg/h with PCM integrated solar absorber was found to be about 67.88% and 6.96%, respectively. The integration of cylindrical PCM containers resulted in more heat transfer augmentation in the solar absorbers. The optimized solar absorber could be suitable for various applications like steam generation, biomass gasification, space heating, and hydrogen generation.  相似文献   
48.
The synthesized polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers were characterized by Fourier transform infrared spectroscopy, UV spectra, X-ray diffraction, scanning electron microscope, thermogravimetric analysis, and conductivity studies. The ion-exchange capacities, effect of eluent concentration, elution time, elution behavior, and pH on ion-exchange capacity were also studied to exploit the ion-exchange capability of the composites. The study revealed that polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate ion exchangers are having excellent ion-exchange capacity values for K+ ion 1.36 and 1.44?meq?g?1, respectively. The organic polymeric part of the composites provides mechanical and chemical stability, whereas the inorganic part supports the ion-exchange behavior and thermal stability. The increase in electrical conductivity is due to the inorganic and organic parts. A mechanism for the formation of the polyaniline-Zr(IV) selenoiodate and polyaniline-Zr(IV) selenomolybdate composite ion exchangers is discussed, which may also be applied for the preparation of other composite ion exchangers. Sorption behavior of metal ions on the composites was studied in different solvent systems. On the basis of distribution coefficient values (Kd), it has been found that the cation-exchange materials are highly selective for Pb(II)-ions. Such modified composite materials can be applied as an electrochemically switchable ion exchanger for water treatment, especially water softening.  相似文献   
49.
The heating value of a fuel affects both the brake thermal efficiency and combustion characteristics of an engine. Its value for fuel blend cannot be calculated based on the blend ratio even though the heating values of blend fuels are known. Therefore, a relationship was formulated from the experimental data to predict the heating values of fuel blends. This study was carried out to compute the theoretical heating values of raw as well as purified pungamia oil with different blend ratio by means of SPSS software (ver. 16). The Durbin–Watson (multiple regressions) tests were carried out in the present study to validate the experimental results. The values of density, flash point, viscosity, and percentage of blends were considered an independent variable, and the heating value was considered a dependent variable for the analysis of heating values of different pungamia oil blends with diesel. The theoretically calculated heating values and relationship between the independent variables were around ± 1%. Also, these values were compared with that of the experimental results of other researchers and the variation was only about 2%. Thus, the validations of developed relation with experimental results show good compliance.  相似文献   
50.
To avoid stockouts and maintain product availability, retailers typically carry excess units and subsequently incur higher cost. In case of style/fashion goods, demand forecasting is extremely difficult due to short selling cycles. The purpose of this study was to minimise the cost of excess stocking without compromising product availability. To achieve these conflicting objectives, our study includes two ordering instances and two returns policies. The time between orders subsequently helps resolve demand uncertainty. Existing studies consider only one type of returns policy, that is, returns on the entire purchase quantity; whereas our study considers two types of returns policies: returns on the first order size and returns on the entire purchase quantity. This study also includes models for the retailer and the supply chain system. Analytical and numerical insights into our study enable the retailer to select his appropriate returns policies to maximise his as well as system’s expected profits. We also show that perfect coordination of partners will help them improve their profits considerably.  相似文献   
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