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   1380篇
  免费   50篇
  国内免费   8篇
电工技术   16篇
综合类   1篇
化学工业   243篇
金属工艺   22篇
机械仪表   20篇
建筑科学   62篇
矿业工程   16篇
能源动力   40篇
轻工业   129篇
水利工程   10篇
石油天然气   4篇
无线电   167篇
一般工业技术   183篇
冶金工业   299篇
原子能技术   9篇
自动化技术   217篇
  2023年   6篇
  2021年   18篇
  2020年   13篇
  2019年   20篇
  2018年   33篇
  2017年   12篇
  2016年   31篇
  2015年   29篇
  2014年   36篇
  2013年   82篇
  2012年   45篇
  2011年   72篇
  2010年   62篇
  2009年   66篇
  2008年   63篇
  2007年   66篇
  2006年   67篇
  2005年   51篇
  2004年   47篇
  2003年   35篇
  2002年   35篇
  2001年   27篇
  2000年   29篇
  1999年   29篇
  1998年   71篇
  1997年   42篇
  1996年   27篇
  1995年   20篇
  1994年   29篇
  1993年   19篇
  1992年   24篇
  1991年   9篇
  1990年   12篇
  1989年   20篇
  1988年   11篇
  1987年   14篇
  1986年   12篇
  1985年   14篇
  1984年   14篇
  1983年   8篇
  1982年   15篇
  1981年   6篇
  1980年   17篇
  1979年   9篇
  1978年   8篇
  1977年   11篇
  1976年   12篇
  1975年   9篇
  1973年   6篇
  1972年   5篇
排序方式: 共有1438条查询结果,搜索用时 344 毫秒
1.
2.
The aim of this study was to compare the sensitivities of commercial monoclonal antibody pools to be used as an initial rapid screen for detection of viral antigens in respiratory secretions. The availability of commercial monoclonal antibodies has dramatically improved the detection of viruses by immunofluorescence techniques in exfoliated cells obtained from respiratory secretions. Several companies have recently introduced monoclonal antibody pools to detect the presence of respiratory viruses in a single preparation. Ninety-four stored slide preparations that had previously been examined by individual monoclonal antibodies were tested using three commercial monoclonal antibody pools produced by Sanofi (UK), Dako (UK), and Quadratech (UK). These monoclonal antibody pools had a sensitivity of 79.6%, 90.9%, and 100%, respectively, when compared with the original results. The overall intensity of immunofluorescence was also examined.  相似文献   
3.
The draft Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) contains Cryptosporidium log-inactivation CT tables (ozone-in-water concentration [residual], “C” times contact time, T). Depending on water temperature, Cryptosporidium CT values that are listed are 15 to 25 times greater than CT values for equivalent Giardia log-inactivation credit. The elevated operating dose required for Cryptosporidium log-inactivation credit has the potential to increase disinfection by-product (DBP) formation (e.g., bromate). Calculating CT value accurately will minimize ozone dose, which will decrease operating cost and lower DBP formation, and at the same time maintain disinfection protection through implementation of scientifically based safety factors. Various methods are available for calculating CT value. The method chosen depends largely on the available information concerning ozone residual characteristics and hydrodynamic features of the ozone contactor, plus local regulatory requirements. Four methods are discussed in this paper. Each method can be used to calculate Giardia, virus, and Cryptosporidium log-inactivation credit.  相似文献   
4.
Nanostructured polymer blends prepared via anionic ring opening polymerizations of cyclic monomers in the presence of a pre-made polymer melt exhibit a number of special properties over traditional polymer blends and homopolymers. Here, we report on a simple and versatile method of in situ polymerization of macrocyclic carbonates in the presence of a maleic anhydride polypropylene (mPP) matrix and a surface-active compatibilizer (i.e. PC grafted onto a mPP backbone generated in situ) to yield a micro- and nanostructured polymer blends consisting of a polycarbonate (PC) minor phase, and a polypropylene (PP) major phase. By varying the processing conditions and concentration of the macrocyclic carbonate it was possible to reduce the size of the PC dispersions to an average minor diameter of 150 nm. NMR and TEM characterizations indicate that the PC dispersions do not influence crystal content in the PP phase. Overall, the results point to a simple strategy and versatile route to new polymeric materials with enhanced benefits.  相似文献   
5.
6.
The present study shows that extracellular adenosine triphosphate (ATP) has the capacity to mediate dose-dependent lysis of the monocytic leukemia cell line THP-1. The lysis, assessed by 51Cr release, was found to be selective for ATP, because adenosine diphosphate (ADP) or other nucleotides were less effective in their ability to lyse the cells. The amount of 51Cr released was particularly enhanced by the stimulation of the cells with 1,000 U/mL of interferon gamma (IFN-gamma) for 3 days, and the sensitivity was time and dose dependent. Analysis of the mechanism of lysis indicated that the fully ionized form, ATP4-, mediated the lysis, because the addition of cation chelators or the absence of the divalent cations, Ca2+ and Mg2+, in the culture medium of a 6-hour 51Cr release assay increased the percent specific lysis. Therefore, the ATP receptors on THP-1 cells were classified as P2Z purinoceptors. Moreover, it is shown here that the Ca2+/calmodulin complex plays a role in the regulation of the lysis by extracellular ATP of THP-1 cells, because antagonists of this complex, such as trifluoperazine or KN-62, were found to inhibit the ATP-mediated cell lysis.  相似文献   
7.
The majority of Ss included in studies of psychopathology are typically receiving psychoactive medication. In view of concerns regarding the confounding effects of psychoactive medication, it appears that researchers should provide information regarding at least the drug status of the Ss studied. A review of the articles on adult psychopathology that appeared in the Journal of Abnormal Psychology during a 5-yr period, however, revealed that nearly 50% of reports on Ss presumably receiving psychoactive medications failed to specify the medication status of those Ss. Few studies (15%) provided adequate information regarding the types and dosages of psychoactive drugs received by the Ss. It is argued that researchers should provide a full report of the psychoactive drugs received by research participants and, when participants are unmedicated, to indicate the reasons for drug-free status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
Presents remarks from the president of the APA's Division 13 (Division of Consulting Psychology). The author discusses the second annual Colorado conference on consulting to corporations and business; the planning for Division activities at the APA convention in Los Angeles; and the affect of health reform on consulting psychology and consulting psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Tension and vascular headache patients, initially treated with biofeedback and/or relaxation training in either a minimal therapist contact protocol (3 visits) or an intensive individual protocol (10 or 16 visits) were followed-up prospectively for 2 years. In the first study, for the first 6 months of follow-up, half of all patients continued to keep headache diaries and were seen monthly and the other half had only minimal contact. The results at 1-year follow-up, based on 4 weeks of daily headache diaries, revealed equally good maintenance from both treatment protocols and from both follow-up conditions. In Study 2, we found that patients remained improved over pretreatment baseline levels at the 2-year follow-up regardless of initial treatment intensity. Approximately three quarters of vascular patients who were initially improved at posttreatment remained improved at 2 years. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
Studied the relationship among age, physical health status, and psychic and somatic symptoms of depression among elderly adults. Human Ss: 318 male and female Canadian older adults (aged 65–102 yrs). Information on sociodemographic factors and health status was obtained using the Older American Research Scale, French version, by R. Lefran?ois et al (1988). A French version by P. Bourque and D. Beaudette (1982) of the Beck Depression Inventory was also used. The results were evaluated according to each S's sex, age, institutionalized residence status, and health status. Statistical tests were used. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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