全文获取类型
收费全文 | 327439篇 |
免费 | 4172篇 |
国内免费 | 737篇 |
专业分类
电工技术 | 6381篇 |
综合类 | 578篇 |
化学工业 | 50520篇 |
金属工艺 | 10770篇 |
机械仪表 | 9134篇 |
建筑科学 | 8710篇 |
矿业工程 | 943篇 |
能源动力 | 9020篇 |
轻工业 | 32222篇 |
水利工程 | 2749篇 |
石油天然气 | 3858篇 |
武器工业 | 8篇 |
无线电 | 40808篇 |
一般工业技术 | 61176篇 |
冶金工业 | 60439篇 |
原子能技术 | 5597篇 |
自动化技术 | 29435篇 |
出版年
2021年 | 2482篇 |
2019年 | 2367篇 |
2018年 | 3860篇 |
2017年 | 3707篇 |
2016年 | 3866篇 |
2015年 | 2775篇 |
2014年 | 4832篇 |
2013年 | 15353篇 |
2012年 | 7996篇 |
2011年 | 10903篇 |
2010年 | 8542篇 |
2009年 | 9789篇 |
2008年 | 10359篇 |
2007年 | 10377篇 |
2006年 | 9171篇 |
2005年 | 8492篇 |
2004年 | 8320篇 |
2003年 | 7989篇 |
2002年 | 7824篇 |
2001年 | 7853篇 |
2000年 | 7516篇 |
1999年 | 7837篇 |
1998年 | 18019篇 |
1997年 | 13168篇 |
1996年 | 10417篇 |
1995年 | 8165篇 |
1994年 | 7456篇 |
1993年 | 7204篇 |
1992年 | 5555篇 |
1991年 | 5256篇 |
1990年 | 5158篇 |
1989年 | 5007篇 |
1988年 | 4907篇 |
1987年 | 4106篇 |
1986年 | 4255篇 |
1985年 | 4956篇 |
1984年 | 4524篇 |
1983年 | 4256篇 |
1982年 | 3794篇 |
1981年 | 3977篇 |
1980年 | 3661篇 |
1979年 | 3629篇 |
1978年 | 3422篇 |
1977年 | 4008篇 |
1976年 | 5013篇 |
1975年 | 2945篇 |
1974年 | 2795篇 |
1973年 | 2827篇 |
1972年 | 2306篇 |
1971年 | 2039篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
R Gollamudi Z Feng EO Dillingham SE Bond G Han S Salgia 《Canadian Metallurgical Quarterly》1993,69(4):361-367
This investigation retrospectively examined changes in marital satisfaction following stroke. The relationship between such changes and other pertinent factors were also examined, including severity of aphasia, knowledge of aphasia, number of months after stroke, and length of the marriage. The subjects were 40 spouses of patients with aphasia grouped according to severity of the aphasia (mild, moderate, severe). Spouses completed two different measures of marital satisfaction--the Marital Satisfaction Scale (MSS) and the Marital Comparison Level Index (MCLI). These measures were completed in both a prestroke (retrospective reporting) and a poststroke format to allow for change to be assessed. In addition, a Knowledge of Aphasia questionnaire was completed by the normal spouses to evaluate their understanding of the disorder of aphasia. There was a significant difference between prestroke and poststroke scores on both the MSS and the MCLI, indicating a lower level of satisfaction following the stroke. The amount of change between prestroke and poststroke MSS and MCLI scores was not related to either number of months poststroke or number of years married. Although there was no relationship between changes in prestroke and poststroke scores on the MCLI and Knowledge of Aphasia scores, there was a significant correlation between changes in these scores on the MSS and Knowledge of Aphasia scores. Hence, the more knowledge spouses had regarding aphasia, the less the negative impact the stroke had on marital satisfaction, as measured by the MSS. Results are discussed in terms of the interdisciplinary treatment needs of aphasic patients and the implications for future investigations. 相似文献
64.
14 medicated hypertensive, 15 nonmedicated mild hypertensive, 39 normotensive, and 13 hypotensive adults participated in a 1–2 hr laboratory experiment that assessed each S's symptoms, moods, and estimates of systolic blood pressure (SBP) relative to actual SBP levels. Several self-reports and autonomic measures were collected during and after each of 22 tasks. Within-S correlations indicated that all Ss could estimate SBP at levels greater than chance. Further, 68% of the Ss evidenced at least 1 significant symptom–SBP correlation. Although medicated hypertensives believed they could estimate their BP more accurately than other groups, they were actually no more accurate than the other Ss. They also evidenced far fewer empirically derived symptom–SBP and emotion–SBP correlations than any other group. Overall, blood pressure (BP) beliefs were largely inaccurate. If these erroneous beliefs can be eliminated, Ss may be able to estimate BP fluctuations more accurately. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
66.
67.
This study contrasted six subscales of the Brief Psychiatric Rating Scale (BPRS) to determine their sensitivity to psychosocial treatment outcome. An expanded version of the BPRS was administered to 216 clients on admission to a day program. The subscale measuring hostility and suspiciousness discriminated at intake clients who were therapeutically discharged from clients who did not complete the program and predicted discharge status after the investigators controlled for the effects of demographic variables. Significant reductions in scores were obtained on five subscales for a subset of clients to whom the BPRS was readministered before discharge. The results support the use of the expanded BPRS as an evaluative tool in psychosocial rehabilitation programs. 相似文献
68.
E Messou SV Sangaré R Josseran C Le Corre J Guélain 《Canadian Metallurgical Quarterly》1997,90(1):44-47
BACKGROUND: Gastric sucrose permeability is a noninvasive marker that reliably increases in association with gastrointestinal injury due to use of nonsteroidal antiinflammatory drugs. Despite the effect of Helicobacter pylori infection on the gastric mucosa, in a previous study we were unable to demonstrate that H. pylori infection was associated with abnormal gastric sucrose permeability. Our goal in this study was to explore further whether H. pylori infection changed gastric permeability; therefore, we evaluated the effect of treatment of H. pylori infection on gastric permeability to sucrose and the relation of sucrose permeability to density of polymorphonuclear leukocytes. MATERIALS AND METHODS: Five hundred milliliters of a solution containing 100 gm of sucrose was ingested by the subject at bedtime. Overnight urine was collected and assayed for sucrose by high-performance liquid chromatography. Sucrose permeability was assessed both before and approximately 4 weeks after anti-H. pylori therapy. RESULTS: Seventeen asymptomatic H. pylori-infected volunteers participated; 8 were cured. Sucrose permeability was in the range commonly found in normal controls both before and after anti-H. pylori therapy (mean excretion, 76.3 mg; range, 13-171 mg). Gastric sucrose permeability correlated with the density of polymorphonulcear cell infiltration of the mucosa. Cure of the H. pylori infection was associated with a small but significant decrease in sucrose permeability (98.8 +/- 18 mg to 51.7 +/- 9.8 mg (p = .01). Sucrose permeability was greater in those with a high density of mucosal polymorphonuclear cells compared to those with lower scores (119.5 +/- 4 vs 71.4 +/- 13 for those with scores > or = 5 compared to scores < or = 4; p = .023). Failed therapy resulted in an increase in the mucosal density of polymorphonuclear infiltration and sucrose permeability (56.4 +/- 13 mg-99.7 +/- 19 mg pretreatment vs posttreatment, respectively; p = .031). CONCLUSION: H. pylori gastritis causes a small but measurable increase in gastric permeability to sucrose that may reflect epithelial transmigration of neutrophils. 相似文献
69.
70.