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   36219篇
  免费   1450篇
  国内免费   60篇
电工技术   369篇
综合类   29篇
化学工业   7140篇
金属工艺   724篇
机械仪表   738篇
建筑科学   1964篇
矿业工程   114篇
能源动力   1056篇
轻工业   2910篇
水利工程   431篇
石油天然气   117篇
武器工业   5篇
无线电   2483篇
一般工业技术   6146篇
冶金工业   6651篇
原子能技术   269篇
自动化技术   6583篇
  2023年   202篇
  2022年   348篇
  2021年   680篇
  2020年   461篇
  2019年   620篇
  2018年   780篇
  2017年   694篇
  2016年   832篇
  2015年   755篇
  2014年   1042篇
  2013年   2374篇
  2012年   1684篇
  2011年   2097篇
  2010年   1656篇
  2009年   1549篇
  2008年   1804篇
  2007年   1778篇
  2006年   1595篇
  2005年   1443篇
  2004年   1176篇
  2003年   1124篇
  2002年   1052篇
  2001年   706篇
  2000年   550篇
  1999年   599篇
  1998年   598篇
  1997年   587篇
  1996年   556篇
  1995年   575篇
  1994年   529篇
  1993年   514篇
  1992年   502篇
  1991年   288篇
  1990年   421篇
  1989年   393篇
  1988年   324篇
  1987年   357篇
  1986年   316篇
  1985年   421篇
  1984年   421篇
  1983年   318篇
  1982年   298篇
  1981年   282篇
  1980年   269篇
  1979年   270篇
  1978年   250篇
  1977年   226篇
  1976年   210篇
  1975年   195篇
  1974年   173篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
The effects of celebrity self-disclosure of HIV seropositivity on perceptions of HIV and AIDS were investigated. AIDS-related interest and knowledge measures were collected from 468 men before and after basketball star Earvin "Magic" Johnson's self-disclosure of HIV seropositivity. Increased interest in AIDS paralleled media coverage of the announcement, with the most substantial effects occurring within 2 wks. Perceived impact of the disclosure was greatest among African-American men and men who had not previously known someone with HIV/AIDS. Celebrity self-disclosure appears to affect perceptions through mechanisms similar to those involved in personally knowing someone infected with HIV. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
162.
Investigated relationships between the performance levels of incumbents on job skills and the importance attributed to those job skills. Supervisors and job incumbents rated both the performance of skill dimensions and the importance of those skills for respective incumbents' positions. Results indicate that the ratings of performance and importance on matched skill areas correlated positively, although relationships were somewhat stronger for incumbent data as compared with data provided by supervisors. Supervisors and incumbents agreed moderately on which skill areas were important for various positions, but the interrater agreement was much lower for performance ratings of the skill areas. For some skill areas, incumbent-rated importance and supervisor-rated performance, as well as incumbent-rated performance and supervisor-rated importance, were significantly correlated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
163.
The observation that natural curves and surfaces are often fractal suggests that people may be sensitive to their statistical properties. The perceptual protocols that underlie discrimination between fractals and between other types of random contour and fractals are examined. Discrimination algorithms that have precisely the same sensitivities as human observers are constructed. These algorithms do not recognize the integrated scale hierarchy intrinsic to fractal form and operate by imposing a metatheory of structure that is based on a signal–noise distinction. The success of the algorithms implies that (1) self-affinity in random fractals is not perceptually recovered and (2) people have a natural disposition to view contour in terms of signal and noise. The authors propose that this disposition be understood as a principle of perceptual organization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
164.
When dopants are indiffused from a heavily implanted polycrystalline silicon film deposited on a silicon substrate, high thermal budget annealing can cause the interfacial “native” oxide at the polycrystalline silicon-single crystal silicon interface to break up into oxide clusters, causing epitaxial realignment of the polycrystalline silicon layer with respect to the silicon substrate. Anomalous transient enhanced diffusion occurs during epitaxial realignment and this has adverse effects on the leakage characteristics of the shallow junctions formed in the silicon substrate using this technique. The degradation in the leakage current is mainly due to increased generation-recombination in the depletion region because of defect injection from the interface.  相似文献   
165.
166.
The photosensitizing properties of p-nitroacetophenone (PNAP), a well-known radiosensitizer, have been studied in near UV region. The mechanism of PNAP photosensitization has been investigated by testing the efficiency of singlet oxygen production using photooxidation of 2,2,6,6-tetramethylpiperidine (TEMP) and photodegradation of guanosine. In both the cases, the enhancement effect of deuterated solvents has been observed. Results of these experiments suggest the significant role of type II mechanisms in PNAP photosensitization.  相似文献   
167.
Comments that L. B. Silverstein's (see record 1992-05293-001) article on child care and maternal employment contributes unfounded and damaging misbeliefs regarding fathers. The dad-as-cad myth suggests intentional malevolence or at least blatant failure by fathers to care for others, and suggests that their failure to share equally in child care and household management is the primary cause of marital conflict. W. B. Johnson and D. Hayes propose a research agenda for fathering that originates in a coherent model of male development in the context of ever-changing environmental demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
168.
169.
Discusses issues and interventions for working with adolescents who live in stepfamilies. A developmental perspective, using psychoeducation and brief strategic intervention approaches, is proposed for working with stepfamilies. Six major issues for adolescents in stepfamilies are discussed: developmental issues, sexuality issues, parent–child relationships, parenting in stepfamilies, nonresidential parent–child issues, and changes in visitation and custody. Case illustrations and suggested interventions are presented for each of these areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
170.
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