全文获取类型
收费全文 | 1116篇 |
免费 | 6篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 115篇 |
金属工艺 | 35篇 |
机械仪表 | 21篇 |
建筑科学 | 20篇 |
矿业工程 | 9篇 |
能源动力 | 20篇 |
轻工业 | 47篇 |
水利工程 | 27篇 |
石油天然气 | 3篇 |
无线电 | 76篇 |
一般工业技术 | 118篇 |
冶金工业 | 519篇 |
原子能技术 | 17篇 |
自动化技术 | 81篇 |
出版年
2021年 | 19篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2016年 | 8篇 |
2014年 | 10篇 |
2013年 | 34篇 |
2012年 | 21篇 |
2011年 | 24篇 |
2010年 | 30篇 |
2009年 | 21篇 |
2008年 | 25篇 |
2007年 | 29篇 |
2006年 | 19篇 |
2005年 | 31篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 25篇 |
2001年 | 22篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 101篇 |
1997年 | 68篇 |
1996年 | 46篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 32篇 |
1992年 | 23篇 |
1991年 | 12篇 |
1990年 | 31篇 |
1989年 | 29篇 |
1988年 | 19篇 |
1987年 | 22篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 15篇 |
1976年 | 38篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1972年 | 11篇 |
1971年 | 5篇 |
1970年 | 5篇 |
排序方式: 共有1122条查询结果,搜索用时 15 毫秒
101.
Selective ET(A) receptor antagonism reduces neointimal hyperplasia in a porcine coronary stent model
CJ McKenna SE Burke TJ Opgenorth RJ Padley LJ Camrud AR Camrud J Johnson PJ Carlson A Lerman DR Holmes RS Schwartz 《Canadian Metallurgical Quarterly》1998,97(25):2551-2556
BACKGROUND: As endothelin binds to ET(A) receptors, it stimulates vascular smooth muscle cell proliferation and may thus be pivotally involved in the pathogenesis of restenosis. This study assessed the ability of a potent and selective ET(A) antagonist to reduce neointimal hyperplasia in a porcine coronary artery stented injury model. METHODS AND RESULTS: Fifty-five pigs were randomized to receive placebo or the oral ET(A)-selective antagonist ABT147627 twice daily for 28 days in one of three doses: 0.75 mg/kg (low), 3.75 mg/kg (mid), and 10.0 mg/kg (high). Each underwent oversized stent deployment in two randomly assigned major epicardial coronary arteries. Three animals (5.5%) died as a consequence of stent thrombosis within 24 hours of the procedure. The remaining 52 animals (13 pigs per group) survived without complication until predetermined euthanasia at 28 days. In the placebo group, mean injury score was 1.73+/-0.80, with a mean neointimal response of 0.45+/-0.24 mm. By comparison, the low-dose group had a similar mean injury score of 1.79+/-0.75 with reduced neointimal response, 0.36+/-0.22 mm (P<0.01). Mean injury score in the mid-dose animals was significantly greater than in the placebo group (1.94+/-0.92; P<0.05). The neointimal hyperplasia associated with this injury was less than with placebo, although the difference did not reach statistical significance (0.40+/-0.25 mm; P=0.05). In the high-dose pigs, mean injury score was also significantly greater than in the placebo arm (1.93+/-0.73; P<0.05). Despite this, neointimal response was also significantly less (0.37+/-0.37 mm; P<0.01). CONCLUSIONS: Oral, selective ET(A) receptor antagonism significantly reduced neointimal hyperplasia forming over porcine coronary stented injuries in the first 28 days. This strategy may have clinical potential for the limitation and treatment of coronary restenosis after percutaneous revascularization. 相似文献
102.
Manitoba's Rural and Northern Community-Based Training Program for Psychology Interns and Residents.
McIlwraith Robert D.; Dyck Karen G.; Holms Valerie L.; Carlson Torie E.; Prober Nancy G. 《Canadian Metallurgical Quarterly》2005,36(2):164
This article describes a unique internship training experience developed by the Department of Clinical Health Psychology of the Faculty of Medicine of the University of Manitoba. Interns live in and provide services to remote northern communities for half of the internship year and receive supervision from a psychologist in the community, supplemented by telehealth. The department also offers a full-year, postdoctoral rural residency. Ten interns and 4 residents have been trained so far. The community-based generalist training model and responses to the challenges, for both supervisors and trainees, of working in small underserved communities are described. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
The status of a-Si solar cell technology is reviewed. This review includes a discussion of the types of solar cell structure that are being used in commercial products. An overview of the development efforts under way involving new materials, such as alloys and microcrystalline films, and their impact on device performance is given. The status of stability in a-Si solar cells and projections for costs for large-scale manufacturing facilities are reviewed. The development of markets for a-Si photovoltaics is also discussed 相似文献
104.
105.
A substantial amount of calcium is transferred from the mother to the fetus and infant during pregnancy and lactation. Involvement of the skeleton in meeting this demand should be reflected in changes in bone mass and turnover. The purpose of the study was to determine the effects of pregnancy, lactation, and recovery on the skeleton in 43 young (prepeak bone mass) female monkeys. Whole body (WBBMC) and lumbar vertebrae 2-4 bone mineral content were determined by dual x-ray absorptiometry at baseline and 1, 4, and 10 months postpartum. Alkaline phosphatase, bone Gla protein, and urinary crosslinks were measured at baseline, during the third trimester, and 1, 4, and 10 months postpartum. Compared to nonpregnant, nonlactating monkeys, pregnant monkeys had similar rates of bone mass gain (nonpregnant, nonlactating WBBMC, 25+/-9 mg/day; pregnant WBBMC, 20+/-14 mg/day). Compared to pregnant monkeys, lactating females had increased bone turnover, as indicated by elevated bone biomarker levels (lactating alkaline phosphatase, 259+/-20 IU/L) and decreased bone mass (lactating WBBMC, -99+/-21 mg/day). Densitometry showed that bone mass gain in the lactating monkeys did not compensate for lactational loss by 10 months postpartum (WBBMC, 6.95+/-9 mg/day). This lack of recovery may have been due to the fact that serum estrogen concentrations were just beginning to return to baseline at 10 months postpartum. In conclusion, the cynomolgus monkey skeleton responds similarly to that of women during pregnancy and lactation. Recovery from lactational bone loss is not complete by 10 months postpartum. 相似文献
106.
Schmidt Kristen L.; Stark Kevin D.; Carlson Caryn L.; Anthony Bruno J. 《Canadian Metallurgical Quarterly》1998,66(4):673
Mood disorders and attention deficit–hyperactivity disorder (ADHD) co-occur in 20–30% of children and adolescents diagnosed in both epidemiological and clinical studies, but little information is available regarding cognitive factors that may be relevant to the expression of co-occurring mood disorders and ADHD. This study examined whether ADHD with and without a comorbid mood disorder could be differentiated on the basis of cognitive factors associated with prominent theories of depression. Children meeting diagnostic criteria for ADHD (n?=?14) or ADHD and a comorbid mood disorder (n?=?27) were assessed on a variety of cognitive indices. Children in the comorbid group reported more negative views of themselves and a more depressogenic attributional style. Cognitive disturbances associated with A. T. Beck's (1967) cognitive model and attributional style theories of depression differentiate ADHD children with significant mood pathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
108.
The aim of this study was to determine immunogenetic markers of susceptibility in Crohn's disease (CD), taking the different features of the clinical course of the disease into account. HLA class I, HLA class II and TAP transporter gene polymorphisms were studied using DNA typing methods. Gene and antigen frequencies were analysed and compared in a group of 102 CD patients and 200 unrelated healthy controls from the same area. Analysis of the whole CD patient population revealed no definite association with either HLA or TAP gene alleles, with the exception of an association with DRB1*1302 (Pc < 0.05). However, when clinical subgroups of patients were considered, specific associations with some genetic markers were found. The most definitive results involved a genetic association in the group of patients who did not respond to glucocorticoid therapy. This group was characterized by a high frequency of HLA-DRB1*04 (P < 0.05). Conversely, a positive association with the TAP2-A allele was found in cortico-responder patients (Pc < 0.03). Furthermore, analysis of the distribution of HLA class II alleles in relation to the presence of extra-intestinal manifestations revealed an association with the DQB1*0501 or *0503 suballele of DQ5 (P < 0.05). Finally, patients with lesions in the small bowel were more frequently HLA DRB1*07 (P < 0.05). The present study supports the concept of clinical heterogeneity in Crohn's disease associated with a background of genetic heterogeneity. 相似文献
109.
110.
An ion chromatographic (IC) method was developed for determining phosphine (PH3) in whole grains (barley, corn, oats, rice, rye, and wheat) and soybeans. The method converts phosphine to phosphate (i.e., orthophosphate) and isolates the phosphate by IC with eluent-suppressed conductivity detection. Recoveries of unbound phosphine by the method were similar to those obtained by an established colorimetric method for 7 different products fortified at 3 levels. Mean recoveries were low (i.e., 30-60%) and varied with product type and level of fortification. Recoveries of PH3 from previously fumigated products fortified with aluminum phosphide ranged from 19.0% for barley fortified at 0.734 ppm to 88.3% for corn fortified at 1.691 ppm. Precision data from 3 products based on replicate analyses (n = 4 or 5) gave relative standard deviations of 1.78-4.66% for mean laboratory-fumigated PH3 levels of 0.679-1.309 ppm. Estimated limits of detection (LOD) and quantitation (LOQ) for PH3 were 0.010 microgram/g (10 ppb) and 0.0275 microgram/g (27.5 ppb) at signal-to-noise ratios (S/N) of 4:1 and 10:1, respectively. These values were also determined for a nonchemically suppressed IC system with LOD of 0.02 microgram/g (20 ppb) and LOQ of 0.055 microgram/g (55 ppb) at S/N of 4:1 and 10:1, respectively. Phosphate response was linear over the concentration range equivalent to 0.30-10.0 micrograms P/mL, with a mean correlation coefficient of 0.9988 based on replicate standard curves. The relationship of product composition to recovery from various products was also examined. 相似文献