全文获取类型
收费全文 | 2174篇 |
免费 | 26篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 143篇 |
金属工艺 | 22篇 |
机械仪表 | 33篇 |
建筑科学 | 58篇 |
矿业工程 | 7篇 |
能源动力 | 29篇 |
轻工业 | 89篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
无线电 | 122篇 |
一般工业技术 | 165篇 |
冶金工业 | 1365篇 |
原子能技术 | 25篇 |
自动化技术 | 114篇 |
出版年
2021年 | 6篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 22篇 |
2015年 | 7篇 |
2014年 | 15篇 |
2013年 | 49篇 |
2012年 | 28篇 |
2011年 | 38篇 |
2010年 | 30篇 |
2009年 | 26篇 |
2008年 | 38篇 |
2007年 | 25篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 27篇 |
2002年 | 25篇 |
2001年 | 29篇 |
2000年 | 21篇 |
1999年 | 49篇 |
1998年 | 405篇 |
1997年 | 241篇 |
1996年 | 168篇 |
1995年 | 93篇 |
1994年 | 106篇 |
1993年 | 88篇 |
1992年 | 46篇 |
1991年 | 42篇 |
1990年 | 29篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 27篇 |
1986年 | 17篇 |
1985年 | 32篇 |
1984年 | 20篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 27篇 |
1980年 | 22篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 43篇 |
1976年 | 77篇 |
1975年 | 13篇 |
1974年 | 6篇 |
1972年 | 10篇 |
1970年 | 5篇 |
1969年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有2200条查询结果,搜索用时 0 毫秒
1.
Valproate (VPA) has been shown to interact with all the major antiepileptic drugs (AEDs) through two mechanisms of action: displacement from albumin binding sites and inhibition of drug metabolism. More recently, evidence showed that VPA inhibits the elimination of drugs metabolized by glucuronide conjugation. Lorazepam (LZP), which is primarily eliminated by conjugation with glucuronic acid, is administered concurrently with VPA both in treatment of epilepsy and in patients treated with VPA for psychiatric disorders. Therefore, a significant drug interaction is likely. We investigated such interaction both in in vitro isolated perfused rat liver (IPRL) and in normal subjects. LZP [2 mg, intravenous (i.v.) bolus] was administered to 8 normal volunteers before and after chronic dosing with VPA. In 6 of 8 subjects, VPA significantly decreased LZP plasma clearance by an average of 40% (p < 0.05) and increased LZP concentrations by decreasing formation clearance of the LZP glucuronide. In the IPRL studies, VPA also significantly decreased formation of LZP glucuronide (from 0.72 +/- 0.14 to 0.22 +/- 0.15 ml/h/kg, p < 0.05), indicating that IPRL is a useful tool for evaluation of the effect of VPA on drugs eliminated by glucuronide conjugation. 相似文献
2.
3.
BE Volos IuM Vasil'ev LV Masliaeva IA Snegurskaia 《Canadian Metallurgical Quarterly》1994,(3-4):92-95
Studied in the course of one-stage epidemiologic survey of 1191 individuals were the threshold of gustatory sensitivity to table salt and nycterine natriuresis, relation of these indices to dietary habits, some risk factors for cardiovascular disorders and clinical parameters. Differing relations were established between gustatory sensitivity to table salt and natriuresis and age and gender of the examinees, the level of blood pressure, aggravated heredity in respect of arterial hypertension, smoking and alcohol abuse, this enabling one to embark upon a differential approach to dietetic correction of salt consumption. 相似文献
4.
5.
6.
The processing endoribonuclease RNase E (Rne), which is encoded by the rne gene, is involved in the maturation process of messenger RNAs and a ribosomal RNA. A number of deletions were constructed in order to assess functional domains of the rne gene product. The expression of the deletion constructs using a T7 promoter/RNA polymerase overproduction system led to the synthesis of truncated Rne polypeptides. The smallest gene fragment in this collection that was able to complement a temperature sensitive rnets mutation and to restore the processing of 9 S RNA was a 2.3-kilobase pair fragment with a 1.9-kilobase pair N-terminal coding sequence that mediated synthesis of a 70.8-kDa polypeptide. Antibodies raised against a truncated 110-kDa polypeptide cross-reacted with the intact rne gene product and with all of the shorter C-terminal truncated polypeptides, indicating that the N-terminal part of the molecule contained strong antigenic determinants. Furthermore, by analyzing the Rne protein and the truncated polypeptides for their ability to bind substrate RNAs, we were able to demonstrate that the central part of the Rne molecule encodes an RNA binding region. Binding to substrate RNAs correlated with the endonucleolytic activity. RNAs that are not substrates for RNase E did not bind to the protein. The two mutated Rne polypeptides expressed from the cloned gene containing either the rne-3071 or ams1 mutation also had the ability to bind 9 S RNA, while their enzymatic function was completely abolished. The data presented here suggest that the endonucleolytic activity is encoded by the N-terminal part of the Rne protein molecule and that the central part of it possesses RNA binding activity. 相似文献
7.
How does the visual system retain and combine information about an object across time and space? This question was investigated by manipulating the spatiotemporal continuity and form continuity of 2 perceptual objects over time. In Experiment 1 the objects were viewed in central vision within a single eye fixation, in Experiment 2 they were viewed across a saccadic eye movement, and in Experiment 3 they were viewed at different spatial and retinal locations over time. In all 3 experiments some information about the object was found to be linked to its spatiotemporal continuity, and some information was found to be independent of spatiotemporal continuity. Form continuity was found to produce no effect. The results support a theory of dynamic visual identification according to which information is maintained over time by both episodic object representations and long-term memory representations, neither of which necessarily code specific sensory information. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Dynamic visual identification was investigated in 4 experiments. In Exps 1 and 2, 2 perceptual objects (2 frames, each containing a letter or 1 containing a letter and the other a plus sign) were previewed in the periphery. A saccade brought these objects to central vision. During the saccade the display was changed so that 1 frame contained a letter and the other a plus sign, and the S identified the letter by naming it aloud as rapidly as possible. In Exp 3, the retinal events of Exps 1 and 2 were simulated. In Exp 4, both the preview and the target were presented centrally within a single fixation. In all experiments both object specific and nonspecific preview benefits were observed. These results support a theory in which the preview benefits observed during visual identification arise from 2 processes, object file review and type priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
10.
In a Danish population-based non-Hodgkin's lymphoma registry, 2687 newly diagnosed patients were registered from 1983 to 1992. 39 had testicular involvement (TL) (incidence 0.26/10(5)/year). Median age was 71 years. 24 cases had localised and 15 had disseminated disease. Histologically, all cases were diffuse (65% diffuse centroblastic type). Of the 27 tested, 11% were of T- and 89% of B-immunophenotype. In localised cases, where surgery was supplemented by combination chemotherapy (CCT), the relapse rate was 15.4%. The relapse rate for cases with localised disease treated with other regimens (orchiectomy and/or radiotherapy) was 63.6% (P < 0.05). Median relapse-free survival was 28 and 14 months, respectively. Overall 5-year survival for all cases was 17%. Adverse prognostic factors at the univariate level were stage IV, constitutional symptoms, serum lactic dehydrogenase elevation and performance score (WHO 3-4). It is suggested that the treatment of stage IE/IIE TL should include early CCT and CNS prophylaxis. 相似文献