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   26769篇
  免费   691篇
  国内免费   33篇
电工技术   329篇
综合类   14篇
化学工业   5922篇
金属工艺   516篇
机械仪表   464篇
建筑科学   1159篇
矿业工程   332篇
能源动力   650篇
轻工业   1726篇
水利工程   226篇
石油天然气   245篇
无线电   1712篇
一般工业技术   4077篇
冶金工业   6147篇
原子能技术   265篇
自动化技术   3709篇
  2022年   246篇
  2021年   412篇
  2020年   266篇
  2019年   346篇
  2018年   422篇
  2017年   369篇
  2016年   485篇
  2015年   391篇
  2014年   614篇
  2013年   1651篇
  2012年   937篇
  2011年   1201篇
  2010年   922篇
  2009年   971篇
  2008年   1148篇
  2007年   1063篇
  2006年   973篇
  2005年   881篇
  2004年   743篇
  2003年   711篇
  2002年   705篇
  2001年   485篇
  2000年   390篇
  1999年   446篇
  1998年   440篇
  1997年   427篇
  1996年   474篇
  1995年   443篇
  1994年   451篇
  1993年   436篇
  1992年   431篇
  1991年   271篇
  1990年   410篇
  1989年   387篇
  1988年   336篇
  1987年   404篇
  1986年   348篇
  1985年   441篇
  1984年   463篇
  1983年   398篇
  1982年   375篇
  1981年   297篇
  1980年   298篇
  1979年   357篇
  1978年   299篇
  1977年   238篇
  1976年   217篇
  1975年   245篇
  1974年   217篇
  1973年   224篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi.  相似文献   
92.
Patterns of smoking cessation using 6- and 12-mo follow-up data are reported for 1,261 primary care patients randomized to 3 physician-delivered smoking interventions: advice only (AO), counseling (CI), and counseling plus availability of nicotine-containing gum (CI?+?NCG). One-week point-prevalence cessation rates at 12 mo did not differ among the interventions: AO (15.2%), CI (12.9%) and CI?+?NCG (16.7%). However, maintained cessation rates (abstinent at both 6 and 12 mo) increased with intervention intensity: AO (6.0%), CI (7.8%), and CI?+?NCG (10.0%): Test of trend χ–2?=?5.06, p?=?.02. CI?+?NCG was significantly higher than AO (p?=?.02). The findings support the following conclusions: Brief physician delivered intervention with availability of nicotine-containing gum can have a beneficial long-term effect on smoking cessation, and cohort data as well as point-prevalence rates are important when assessing the long-term impact of lifestyle interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
93.
Evaluated the validity of self-efficacy expectations as predictors of mortality for 119 patients with chronic obstructive pulmonary disease. Ss completed 4 physiological measures that represent common clinical indicators of disease severity: forced expiratory volume in 1 s(FEV1.0), arterial blood gas measurement of resting partial pressure of oxygen (PaO?), single-breath diffusing capacity (DLCO), and maximum oxygen uptake (V02max) during exercise. In addition, self-reported self-efficacy expectation for walking on a treadmill was measured. Self-efficacy was a significant univariate predictor of 5-yr survival. However, when controlling for FEV1.0 in multivariate survival analysis, self-efficacy had only a marginal effect. Simple self-report scales may provide significant information about health status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
Many researchers have found evidence that, when only marginal distributions are examined, extraversion is related primarily to positive affect, whereas neuroticism is related primarily to negative affect. Recent findings have suggested that extraversion and neuroticism interact in predicting mood so that marginal relations could be misleading. The present study used extraversion (and its components, sociability and impulsivity) along with neuroticism in regression equations including interactive and curvilinear components to predict measures of positive and negative affect among 384 undergraduates. Results confirm earlier findings that extraversion and neuroticism interact in predicting both positive and negative affect. The interaction pattern was similar to previous findings: Both positive and negative affect were strongly related to extraversion only among neurotic Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
95.
Reports an error in "Does reward increase or decrease creativity" by Robert Eisenberger and Michael Selbst (Journal of Personality and Social Psychology, 1994[Jun], Vol 66[6], 1116-1127). In the aforementioned article, Figures 1 and 2 were interchanged. The figures appear with their correct captions in the erratum. (The following abstract of the original article appeared in record 1994-40652-001.) Two studies involving 504 school children investigated why behaviorists and cognitively oriented investigators have come to opposite conclusions about reward's effects on creativity. A monetary reward for a high degree of divergent thought in 1 task (word construction) increased children's subsequent originality in a different task (picture drawing). The same reward, made contingent on a low degree of divergent thought, reduced this generalized originality. These effects were eliminated by using a large reward and were restored by keeping the large reward out of the children's sight. The results suggest that reward training increases generalized creativity when (1) a high degree of divergent thought is required and (2) the reward is presented in not too salient a fashion. The findings are consistent with a 2-factor interpretation of rewarded creativity effects that incorporates learned industriousness and selective attention. [A correction concerning this article appears in Journal of Personality & Social Psychology, 1994(Jul), Vol 67(1), 125. Figures 1 and 2 were interchanged.] (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
96.
Comments on K. Humphreys's (see record 1994-34917-001) article discussing the limitations of integrating psychotherapy and 12-step programs. Humphreys's arguments based on the approaches' purported differences in helping values are not logically demonstrated or empirically determined. Therapists should be trained to deal with spiritual issues and perspectives in a respectful and knowledgeable way. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
97.
The question of "What makes things seem similar?" is important both for the pivotal role of similarity in theories of cognition and for an intrinsic interest in how people make comparisons. Similarity frequently involves more than listing the features of the things to be compared and comparing the lists for overlap. Often, the parts of one thing must be aligned or placed in correspondence with the parts of the other. The quantitative model with the best overall fit to human data assumes an interactive activation process whereby correspondences between the parts of compared things mutually and concurrently influence each other. An essential aspect of this model is that matching and mismatching features influence similarity more if they belong to parts that are placed in correspondence. In turn, parts are placed in correspondence if they have many features in common and if they are consistent with other developing correspondences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
99.
100.
In this article, the author attempts to show that Lacan's early writings are relevant to the author's own psychoanalytic perspective by virtue of Lacan's view of the psychoanalytic method and process as phenomenological, hermeneutic, and dialogic. (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