全文获取类型
收费全文 | 1108篇 |
免费 | 6篇 |
专业分类
化学工业 | 36篇 |
金属工艺 | 16篇 |
机械仪表 | 1篇 |
建筑科学 | 9篇 |
轻工业 | 14篇 |
无线电 | 15篇 |
一般工业技术 | 16篇 |
冶金工业 | 996篇 |
原子能技术 | 5篇 |
自动化技术 | 6篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2013年 | 12篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 27篇 |
1998年 | 302篇 |
1997年 | 181篇 |
1996年 | 112篇 |
1995年 | 53篇 |
1994年 | 62篇 |
1993年 | 61篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 35篇 |
1976年 | 82篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1114条查询结果,搜索用时 0 毫秒
991.
R Chammas MG Jasiulionis AM Ventura LR Travassos RR Brentani 《Canadian Metallurgical Quarterly》1996,29(9):1141-1149
Malignant transformation is accompanied by changes in cell-matrix interactions. Upon transfection with EJ-ras oncogene, transformed fibroblasts acquired a migratory phenotype towards laminin-1. The increase in integrin expression was responsible for the migratory activity of transformed fibroblasts. In addtion alpha 6 beta 1 integrins, both galectin-3 and an unidentified laminin-binding polypeptide had their expression pattern altered upon transformation. Here, we review these two classes of laminin-binding proteins and their possible roles in cell-laminin interactions. 相似文献
992.
This report describes a case of t(15;17) acute promyelcytic leukaemia (APL, FAB subtype M3) with dysgranulopoiesis at diagnosis in a patient who developed myelodysplasia (MDS) and then a second phenotype of t(7;21) acute myeloblastic leukaemia (AML, FAB subtype M1) at the time of relapse. To our knowledge, there is no report of a second phenotype of AML occurring after complete remission (CR) of APL. Furthermore, this is the first report of chromosomal abnormality t(7;21) in a case of AML. Several hypotheses for this unusual course of APL are discussed. 相似文献
993.
994.
LR Landerman GG Fillenbaum CF Pieper GL Maddox DT Gold JM Guralnik 《Canadian Metallurgical Quarterly》1998,53(5):S258-S266
OBJECTIVES: This study examines the relationship between the lack of private supplemental health insurance coverage and the development of disability among adults aged 65 and older. METHODS: Data are from the baseline and six follow-up waves of the Duke Established Populations for Epidemiologic Studies of the Elderly survey (N = 4,000). Discrete-time hazard models were used to estimate the impact of insurance coverage and other risk factors on the incidence of disability among those unimpaired at baseline. RESULTS: Controlling for education, income, and other potential confounders, the odds of developing disability were 35-49% higher among those without private coverage. Insurance coverage also statistically explained part of the increased risk of disability among low-income persons. DISCUSSION: The results indicate that changes in health insurance coverage as well as in individual behaviors may be needed to reduce disability generally and disability among the socioeconomically disadvantaged, in particular. 相似文献
995.
BW Aichbichler HH Wenzl CA Santa Ana JL Porter LR Schiller JS Fordtran 《Canadian Metallurgical Quarterly》1998,43(11):2353-2362
In people with constipation, it is not known if decreased frequency of defecation is associated with abnormalities in the weight or in the consistency of stools or if the weight or the consistency of stools correlates with the severity of various discomforts associated with bowel movements. In neither normal nor constipated subjects has the consistency of stools been carefully correlated with their relative contents of water and solids. Our aim was to gain insight into these questions. Twenty subjects with idiopathic chronic constipation and 20 age- and sex-matched control subjects were recruited by advertisement. Stools were collected for one week. After each bowel movement, the subject's perception of various discomforts associated with the bowel movement were recorded. The stools were then analyzed. The results and conclusions were as follows: (1) Stool weight per bowel movement was similar in the two groups but stool weight per week was markedly reduced in constipated subjects. (2) Reduced stool weight per week in constipated subjects was due to a nearly proportional reduction in stool water and stool solids output. (3) Using data from both groups, there was a curvilinear correlation between percent insoluble stool solids and stool hardness, as measured by a texture analyzer; hardness increased only slightly as percent insoluble solids increased between 7 and 20%, but hardness increased dramatically when percent insoluble solids exceeded 25%. (4) Only 6% of stools from constipated subjects (2 of 34) had abnormally high values for percent stool solids and physical hardness. (5) In subjects with constipation, the severity of various discomforts associated with bowel movements (such as straining) correlated poorly with the weight or the hardness of stool that was produced by the bowel movement. 相似文献
996.
We sought to determine whether an increased frequency of the HLA-DR11 (formerly DR5) phenotype is found in human immunodeficiency virus (HIV)-infected children with parotid gland enlargement. In HIV-infected adults, parotid gland enlargement may be part of the diffuse infiltrative CD8 lymphocytosis syndrome. An increased frequency of expression of HLA-DR11 has been described in association with diffuse infiltrative CD8 lymphocytosis syndrome. We conducted a case-control study with 26 HIV-infected children, 13 of whom had parotid gland enlargement and 13 of whom did not but who were matched for age, race, and sex with those with parotid gland enlargement. Clinical and laboratory parameters (including HLA-DR11 phenotype) were compared between the two groups. HIV-positive children with parotid gland enlargement showed an increased frequency of HLA-DR11, similar to their adult counterparts with diffuse infiltrative CD8 lymphocytosis syndrome. The HLA-DR11 phenotype may be associated with the development of parotid gland enlargement in HIV-infected children and may be a marker for a more benign outcome of HIV infection. 相似文献
997.
R Poggioli AV Vergoni E Rasori D Marrama A Bertolini 《Canadian Metallurgical Quarterly》1992,22(3):149-154
High densities of atriopeptin-immunoreactive fibers and of highly specific and selective atriopeptin receptor sites are present in brain areas involved in animal behavior. The possible influence of these peptides on behavior was thus investigated in adult rats. The intracerebroventricular injection of atriopeptin II modified male sexual behavior (reduction in mount latency) at the dose of 5 micrograms/animal; lower and higher doses were ineffective. Open-field behavior was also modified by i.c.v. atriopeptin II at the doses of 5 and 10 micrograms/rat, which induced an increase in the number of external and internal crossings and of external rearings. Finally, in fasted rats, atriopeptin II, at the dose of 10 micrograms/rat, significantly increased the amount of food intake 30 and 60 min after injection. These findings indicate that atriopeptins may modify different animal behaviors. 相似文献
998.
A comparision of experimental data and theoretical predictions on time resolution limits of fast photomultipliers has been performed. XP 1020 photomultipliers have been used and measurements were done with a fast electronic system built in our laboratory. This system was tested with a Co60 source, the best time resolutions achieved over a period of two hours being 164 psec at f.w.h.m. A hydrogen discharge lamp has been built which produced short light pulses whose shape is determinated by a sampling method. Several light intensities were used to simulate different energy losses in plastic scintillators and time resolution measurements were performed for different threshold settings of the discriminator. The results of these measurements were compared to theoretical data calculated by means of a statistical model of the photomultiplier. Good agreement was found assuming a photoelectronic yield of one photoelectron per 2.5 KeV in Naton 136 plastic scintillator and a single electron response (SER) variance of 500 psec. The necessity of having more accurate data on photomultiplier parameters, mainly concerning the transit time jitter, was pointed out in order to have a better understanding of the photomultiplier's behaviour. 相似文献
999.
C Bazzani L Fiore F Ferrante A Bertolini S Guarini 《Canadian Metallurgical Quarterly》1996,52(4):207-215
In a rat model of volume-controlled hemorrhagic shock (mean arterial pressure = 20-24 mm Hg) causing the death of all saline-treated animals within 30 min, the i.v. bolus injection of ACTH-(1-24) (160 micrograms/kg) produced an almost complete and sustained reversal of the shock condition, with recovery of arterial blood pressure, pulse pressure and respiratory rate, and with 100% survival at the end of the experiment (2 h). The serotonin-depleting agent p-chlorophenylalanine (316 mg/kg i.p., administered 66-70 h before hemorrhage) almost completely prevented the effect of ACTH. The 5-HT1/5-HT2 receptor antagonist, methysergide, prevented the effect of ACTH completely when injected i.v. (5 mg/kg), but only in part when injected into a brain ventricle (i.c.v.) (15 micrograms/rat); the 5-HT2 antagonist, ketanserin, prevented the effect of ACTH completely when injected i.c.v. (1.5 micrograms/rat), but only in part when injected i.v. (0.5 mg/kg); the 5-HT3 antagonist, MDL 72222, largely prevented the effect of ACTH when injected i.c.v. (10 micrograms/rat), but had no influence at all when injected i.v. (3 mg/kg); finally, the 5-HT4 antagonist, GR 125487, had no effect when injected i.v. (5 micrograms/kg) or when injected i.c.v. (30 ng/rat). Overall, these data indicate that both CNS and peripheral serotonin play an important role in the complex mechanism of the ACTH-induced hemorrhagic shock reversal. 相似文献
1000.