全文获取类型
收费全文 | 6715篇 |
免费 | 15篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 69篇 |
金属工艺 | 5篇 |
机械仪表 | 10篇 |
建筑科学 | 4篇 |
能源动力 | 8篇 |
轻工业 | 35篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 33篇 |
一般工业技术 | 43篇 |
冶金工业 | 6477篇 |
自动化技术 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 5篇 |
2015年 | 10篇 |
2014年 | 14篇 |
2013年 | 17篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 158篇 |
1998年 | 1927篇 |
1997年 | 1140篇 |
1996年 | 757篇 |
1995年 | 391篇 |
1994年 | 347篇 |
1993年 | 386篇 |
1992年 | 50篇 |
1991年 | 102篇 |
1990年 | 104篇 |
1989年 | 89篇 |
1988年 | 101篇 |
1987年 | 87篇 |
1986年 | 77篇 |
1985年 | 59篇 |
1983年 | 12篇 |
1982年 | 32篇 |
1981年 | 47篇 |
1980年 | 58篇 |
1978年 | 26篇 |
1977年 | 181篇 |
1976年 | 350篇 |
1975年 | 10篇 |
1955年 | 4篇 |
1954年 | 3篇 |
排序方式: 共有6730条查询结果,搜索用时 12 毫秒
71.
E Legius H Cuppens H Dierick K Van Zandt R Dom JP Fryns G Evers-Kiebooms M Decruyenaere K Demyttenaere P Marynen 《Canadian Metallurgical Quarterly》1994,2(1):44-50
Pantoprazole is a specific inhibitor of the H+/K(+)-ATPase of the gastric parietal cell. The dose-dependency of a range of pantoprazole pharmacokinetic characteristics was studied. Twelve healthy male subjects were given 10, 20, 40 and 80 mg pantoprazole intravenously according to a randomized, single blind, 4-period change-over scheme. The area under the concentration vs time curve (AUC) and the maximum serum concentration (Cmax) showed a linear increase in line with the dose. Apparent volume of distribution (Vd area), clearance (Cl) and terminal half-life (t1/2) were independent of the dose. The dose-independent elimination of pantoprazole was attributed to the lack of interaction of the drug with cytochrome P450. In clinical practice, a good predictable response, as well as a low potential for interaction with other drugs might be expected. 相似文献
72.
OBJECTIVE: To determine the relative influences of induction of withdrawal bleedings secretory transformation, and reduction of mitosis in glands on prevention of endometrial hyperplasia during long-term hormonal replacement therapy. DESIGN: Observational expanded clinical case report. SETTING: Reproductive Endocrine Department of Hospital Necker, Paris, France, and Pathology Department of Women's Hospital, Los Angeles County and University of Southern California Medical Center, Los Angeles, California. PATIENTS: Postmenopausal women seeking treatment for symptomatic menopause. INTERVENTIONS: Endometrial biopsy and/or ambulatory hysteroscopy. MAIN OUTCOME MEASURE: Endometrial histology including progestational maturation patterns and glandular epithelial mitosis rates. Macroscopic endometrial appearance. RESULTS: The use of larger doses of E2 and P induced more marked secretory changes and more frequent withdrawal bleeding than the lower doses. There was no evidence of endometrial hyperplasia after 5 years of E2/P replacement therapy independently of bleeding pattern or progestational maturation. Consistent reduction of mitosis rates in glandular epithelium was found after 9 or more days of P administration in each cycle. CONCLUSIONS: Control of endometrial growth is mainly related to control of mitosis in glands by a relatively low doses of P. Induction of withdrawal bleeding and endometrial secretory transformation, which require larger doses of Progesterone, do not provide additional benefit for prevention of hyperplasia. Induction of amenorrhea with a relatively low dose of P may be offered to women seeking hormone replacement therapy with similar levels of safety. 相似文献
73.
JP O'Bryan Z Songyang L Cantley CJ Der T Pawson 《Canadian Metallurgical Quarterly》1996,93(7):2729-2734
The Shc adaptor protein, hereafter referred to as ShcA, possesses two distinct phosphotyrosine-recognition modules, a C-terminal Src homology 2 (SH2) domain and an N-terminal phosphotyrosine-binding (PTB) domain, and is itself phosphorylated on tyrosine in response to many extracellular signals. Phosphorylation of human ShcA at Tyr-317 within its central (CH1) region induces binding to the Grb2 SH2 domain and is thereby implicated in activation of the Ras pathway. Two shc-related genes (shcB and shcC) have been identified in the mouse. shcB is closely related to human SCK, while shcC has not yet been found in other organisms. The ShcC protein is predicted to have a C-terminal SH2 domain, a CH1 region with a putative Grb2-binding site, and an N-terminal PTB domain. The ShcC and ShcB SH2 domains bind phosphotyrosine-containing peptides and receptors with a specificity related to, but distinct from, that of the ShcA SH2 domain. The ShcC PTB domain specifically associates in vitro with the autophosphorylated receptors for nerve growth factor and epidermal growth factor. These results indicate that ShcC has functional SH2 and PTB; domains. In contrast to shcA, which is widely expressed, shcC RNA and proteins are predominantly expressed in the adult brain. These results suggest that ShcC may mediate signaling from tyrosine kinases in the nervous system, such as receptors for neurotrophins. 相似文献
74.
Impact of apolipoprotein E polymorphism on lipoproteins and risk of myocardial infarction. The ECTIM Study 总被引:2,自引:0,他引:2
G Luc JM Bard D Arveiler A Evans JP Cambou A Bingham P Amouyel P Schaffer JB Ruidavets F Cambien 《Canadian Metallurgical Quarterly》1994,14(9):1412-1419
Human apolipoprotein (apo) E, a polymorphic protein with three common alleles, epsilon 2, epsilon 3, and epsilon 4, plays an important role in lipoprotein metabolism. This article describes the association of this polymorphism with lipids, apolipoproteins, and lipoproteins with a particular regard to lipoprotein particles, as defined by their apolipoprotein content, as well as the risk of myocardial infarction in a multicenter population-based case-control study (ECTIM study). In the ECTIM study, 574 male patients aged 25 to 64 were examined 3 to 9 months after myocardial infarction in four regions participating in the World Health Organization MONICA project: Belfast (Northern Ireland) and Lille, Strasbourg, and Toulouse (France). Control subjects (n = 722) were randomly selected from the regional populations. The distribution of apoE phenotypes was significantly different across the four control samples (P = .04), with a higher frequency of the epsilon 4 allele in Belfast (14.3%) than in Toulouse (8.2%). The association of apoE polymorphism with biological measurements was studied in the control groups (n = 640) after men with coronary heart disease or those taking hypolipidemic drugs were omitted, with the apoE3/3 phenotype as a reference after adjustment for concomitant factors. Individuals carrying the epsilon 2 allele had lower levels of plasma cholesterol, low-density lipoprotein cholesterol (LDL-C), and apoB and higher levels of triglycerides, very-low-density lipoprotein cholesterol (VLDL-C), apoC-III, apoE, lipoprotein (Lp) C-III:B, and Lp E:B. However, the effect of the epsilon 2 allele on triglyceride, VLDL-C, apoE, and Lp E:B parameters was heterogeneous across the populations.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
75.
76.
77.
JP Hubble KL Busenbark S Wilkinson RD Penn K Lyons WC Koller 《Canadian Metallurgical Quarterly》1996,46(4):1150-1153
We examined the effects and safety of deep brain stimulation (DBS) as a treatment for essential tremor (ET). Ten ET patients with disabling medication-refractory tremor underwent stereotactic implantation of a DBS lead in the left Vim thalamic nucleus and completed a 6-month follow-up. The Clinical Tremor Rating Scale and disability assessments were performed at baseline, 1-, 3-, and 6-month follow-up. There were significant improvements in dressing, drinking, eating, bathing, and handwriting as reported by the subjects. Tremor severity, writing, pouring, and spiral and line drawing were significantly improved as rated by the examiner. Improvements persisted through the 6-month follow-up period. Although global disability significantly lessened in the group as a whole, one subject with hand-finger tremor accentuated by writing had no change in disability status. In this 6-month open-label study, DBS was effective and safe in reducing tremor and functional disability in ET. 相似文献
78.
JP Binette MB Binette MA Gawinowicz N Kendrick 《Canadian Metallurgical Quarterly》1996,10(2):509-17; discussion 517-8
The discovery of an organic component in kidney stones dates back to 1684. More than 150 years elapsed before the incrustation of this organic component, which is now called the matrix, was proposed as the mechanism of stone formation. The composition of the matrix remained largely unknown until the development of electron microscopy and the advances in biochemistry combined in the 1950's to usher in the modern era of renal stone matrix investigation. Composed mainly of selectively incorporated proteins generally characterized by high glutamic and aspartic acid content and the frequent occurrence of gamma-carboxyglutamic acid, the matrix displays a variable and complex composition and shares a few proteins in many stones. The embryonic stone may first appear in the renal tubules where it can acquire the blood and cell membrane proteins recently found by analysis of stone protein extracts. The combination of supersaturation, an appropriate environment, the availability of calcium binding proteins which may be abnormal, and the incorporation of proteins extracted from leukocytes and cell wall membranes may induce stone formation. 相似文献
79.
Healy (1) and Dempster et al. (8) proposed statistical methods to evaluate the treatment effects in animal reproductive toxicology research. Both methods assume homogeneous variance for the dams and the pups, respectively, in all the treatment groups. In this paper, via mixed effect modeling, we propose a method to estimate the treatment effects allowing heterogeneous variances for the dams and the pups, respectively, in different treatment groups. Covariates will also be included in the model. A procedure to test the fixed effects is also discussed. An example from an animal reproductive toxicological study is used to illustrate the procedures. 相似文献
80.
JP Guignard 《Canadian Metallurgical Quarterly》1993,50(3):187-189