首页 | 官方网站   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   1270篇
  免费   56篇
工业技术   1326篇
  2023年   11篇
  2022年   9篇
  2021年   36篇
  2020年   17篇
  2019年   16篇
  2018年   30篇
  2017年   22篇
  2016年   38篇
  2015年   30篇
  2014年   52篇
  2013年   67篇
  2012年   51篇
  2011年   79篇
  2010年   62篇
  2009年   46篇
  2008年   54篇
  2007年   50篇
  2006年   49篇
  2005年   44篇
  2004年   50篇
  2003年   40篇
  2002年   23篇
  2001年   18篇
  2000年   22篇
  1999年   22篇
  1998年   60篇
  1997年   43篇
  1996年   31篇
  1995年   17篇
  1994年   14篇
  1993年   23篇
  1992年   7篇
  1991年   8篇
  1990年   13篇
  1989年   7篇
  1988年   14篇
  1987年   7篇
  1986年   8篇
  1985年   7篇
  1984年   5篇
  1983年   10篇
  1982年   7篇
  1981年   8篇
  1980年   8篇
  1979年   6篇
  1977年   12篇
  1976年   31篇
  1975年   7篇
  1973年   11篇
  1972年   6篇
排序方式: 共有1326条查询结果,搜索用时 15 毫秒
101.
Bacteria belonging to the Pectobacterium genus are the causative agents of the blackleg and soft-rot diseases that affect potato plants and tubers worldwide. In Pectobacterium, the expression of the virulence genes is controlled by quorum-sensing (QS) and N-acylhomoserine lactones (AHLs). In this work, we screened a chemical library of QS-inhibitors (QSIs) and AHL-analogs to find novel QSIs targeting the virulence of Pectobacterium. Four N,N′-bisalkylated imidazolium salts were identified as QSIs; they were active at the μM range. In potato tuber assays, two of them were able to decrease the severity of the symptoms provoked by P. atrosepticum. This work extends the range of the QSIs acting on the Pectobacterium-induced soft-rot disease.  相似文献   
102.
A silt fence filter was required to retain potentially toxic particles of 0.1 mm-diameter and larger that could become suspended in water decanted from contaminated dredge spoils. An experimental study was performed to select it. The experiments consisted of two parts, Part 1 tests were conducted according to an accepted engineering standard to compare four candidate geotextiles. Part 2 tests simulated expected field conditions, and were conducted to determine whether one geotextile selected from the Part 1 tests was likely to perform well. The geotextile selected for Part 2 tests retained particles of 0.1 mm and larger, and was installed as a silt fence filter in the field. The silt fence filter was removed shortly after dredging began because it clogged, primarily due to unexpected, high amounts of suspended sediment in the supernatant. The design of the support structure for the silt fence did not permit maintenance of the filter, which may have prevented its failure. The failure may also have been prevented if salt or other materials used to promote flocculation of the dredged spoils were readily available and used on the spoils. The selection procedure described may be helpful because the conditions tested for in the laboratory are likely to occur or could be induced.  相似文献   
103.
Fifty-four adults with primary insomnia were randomly assigned to a self-help treatment (cognitive-behavioral bibliotherapy [BT]), BT with weekly phone consultations, or a waiting-list control (WL) group. Treated participants were mailed 6 treatment booklets at the rate of 1 booklet per week; 1/2 of them also received minimal professional guidance through a 15-min weekly phone consultation. The WL group members continued to monitor their sleep during this period. Participants in both treatment conditions improved significantly on the main outcome variables (total wake time and sleep efficiency) at posttreatment, whereas WL participants remained unchanged. The addition of weekly phone calls slightly enhanced improvements at posttreatment. However, both treatment conditions were comparable at follow-up. These results suggest that BT, with or without minimal professional guidance, is an effective approach for treating primary insomnia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
104.
105.
The reasons why ideally flat H–Si(111) surface can be prepared by NH4F etching are investigated from correlation between AFM observations and experimental conditions used for etching. It is shown that pitting may be completely suppressed if a one side polished wafer is immersed in an oxygen free solution. An analytical electrochemical study of the (111) and rough face of the same n-Si wafer is presented to yield insight into observations.  相似文献   
106.
In this study, a method is developed to determine the oil mist characteristics for the minimal quantity lubricant process. The oil mist is characterized by the size, velocity, and volume flow rate of its particles. In each case, a specific measurement process is used: the laser diffraction granulometry method, the particle image velocimetry, and the gravimetric method. These methods are used in the case of static and simple models with different inner channels. Experimental tests have been done with the same inner channel as the existing spindle inner channel. Different output models with different inner canalizations have been tested, using these experimental processes. The main goal is to control the characteristics of output oil mist as a function of the input oil mist device parameters.  相似文献   
107.
108.
The exocellular β-glucosidases of Candida molischiana and Candida wickerhamii are able to hydrolyse geranyl, neryl, citronellyl, linalyl and α-terpinyl-β-D -glucopyranosides. The nature of the aglycone residue greatly affects the rate of hydrolysis. Glucosides with a tertiary alcohol as aglycone residue are more slowly hydrolysed than those with a primary alcohol. The β-glucosidase from C molischiana is also able to hydrolse α-L-arabinofuranosides. This results in the release of monoterpenols from a glycoside extract from grape juice.  相似文献   
109.
Studied the effect of client and therapist level of experiencing, beginning with the initial stage of psychological counseling, on early termination of therapy. Human subjects: 32 male and female Canadian adults (mean age 30–32 yrs) (personality disorders, neuroses, or interpersonal problems) (clients of therapists). 19 normal male and female Canadian adults (mean age 31 yrs) (graduate students) (therapists). Clients were subdivided into 2 groups: those who had terminated therapy (early or late), and those who had not terminated therapy. Ss were interviewed. Levels of experiencing were compared for the 2 groups of clients and for therapists who had counseled these clients. Tests used: The Global Assessment Scale, Psychiatric Symptom Index (F. Ilfeld, 1976), and Experiencing Scale (P. Mathieu-Coughlan and M. Klein, 1984). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
110.
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-23

京公网安备 11010802026262号