首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2904篇
  免费   27篇
  国内免费   3篇
电工技术   12篇
综合类   1篇
化学工业   76篇
金属工艺   6篇
机械仪表   20篇
建筑科学   21篇
矿业工程   6篇
能源动力   7篇
轻工业   46篇
水利工程   2篇
石油天然气   1篇
无线电   102篇
一般工业技术   86篇
冶金工业   2479篇
自动化技术   69篇
  2021年   4篇
  2020年   10篇
  2019年   3篇
  2018年   11篇
  2017年   9篇
  2016年   14篇
  2015年   10篇
  2014年   17篇
  2013年   21篇
  2012年   14篇
  2011年   26篇
  2010年   15篇
  2009年   12篇
  2008年   15篇
  2007年   15篇
  2006年   14篇
  2005年   10篇
  2004年   16篇
  2003年   9篇
  2002年   8篇
  2001年   15篇
  2000年   13篇
  1999年   100篇
  1998年   779篇
  1997年   490篇
  1996年   297篇
  1995年   172篇
  1994年   126篇
  1993年   174篇
  1992年   24篇
  1991年   23篇
  1990年   34篇
  1989年   24篇
  1988年   21篇
  1987年   23篇
  1986年   25篇
  1985年   27篇
  1984年   3篇
  1983年   8篇
  1982年   20篇
  1981年   18篇
  1980年   24篇
  1979年   11篇
  1978年   9篇
  1977年   67篇
  1976年   124篇
  1975年   4篇
  1968年   3篇
  1966年   3篇
  1955年   4篇
排序方式: 共有2934条查询结果,搜索用时 15 毫秒
51.
AIM: The study of the hypolipidemic efficiency, safety and tolerance of ciprofibrate (lipanor) in therapy of atherogenic hyperlipoproteinemia. MATERIALS AND METHODS: The trial included 14 hypertensive postmenopausal females, 14 patients with diabetes mellitus type II, 14 males with coronary heart disease and primary hyperlipoproteinemia (total cholesterol > 6.5 mmol/l, triglycerides < 4.5 mmol/l under low-cholesterol diet). Lipanor was given for 12 weeks in a daily single dose 100 mg in the morning. Lipids and other biochemical indices were measured in a fasting state after 1 and 3 months of lipanor treatment. RESULTS: After 1 month of lipanor treatment there was a 22-30%, 24-49% decrease in the level of low-density lipoprotein cholesterol, triglycerides, respectively. High-density lipoprotein cholesterol increased by 16%. The hypolipidemic effect of lipanor persisted for 3 months during which triglycerides continued to fall (up to 38.5%). Lipanor was well tolerated, only one patient with diabetes mellitus had hyperactivity of creatine phosphokinase manifesting with clinical symptoms (the drug was discontinued). 3 patients developed mild side effects. Alkaline phosphatase activity inhibited in all the groups by 25-41%. CONCLUSION: Lipanor is a highly effective, safe hypolipidemic drug with good tolerance. It can be recommended for correction of atherogenic hyperlipoproteinemia in patients at high risk of atherosclerosis progression.  相似文献   
52.
A 74-year-old patient sought treatment for visual obscuration and clinically had signs of Graves orbitopathy. Past medical history was unremarkable except for the use of antihypertensive medication. During the hospital admission, a fluorescent treponemal antibody absorption test was reactive, indicating infection with syphilis at some time in the past. Visual deterioration despite oral corticosteroid therapy prompted orbital decompression. At the time of surgery, she sustained a globe rupture. Presumably, syphilitic scleritis was responsible, in part, for scleral thinning and weakening, predisposing her to this complication. To the authors' knowledge, globe rupture has not been previously reported during orbital decompression.  相似文献   
53.
54.
In addition to triggering the activation of B- or T-cell antigen receptors, the binding of a ligand to its receptor at the cell surface can sometimes determine the physiological outcome of interactions between antigen-presenting cells, T and B lymphocytes. The protein SLAM (also known as CDw150), which is present on the surface of B and T cells, forms such a receptor-ligand pair as it is a self-ligand. We now show that a T-cell-specific, SLAM-associated protein (SAP), which contains an SH2 domain and a short tall, acts as an inhibitor by blocking recruitment of the SH2-domain-containing signal-transduction molecule SHP-2 to a docking site in the SLAM cytoplasmic region. The gene encoding SAP maps to the same area of the X chromosome as the locus for X-linked lymphoproliferative disease (XLP) and we found mutations in the SAP gene in three XLP patients. Absence of the inhibitor SAP in XLP patients affects T/B-cell interactions induced by SLAM, leading to an inability to control B-cell proliferation caused by Epstein-Barr virus infections.  相似文献   
55.
The Galileo spacecraft has been orbiting Jupiter since 7 December 1995, and encounters one of the four galilean satellites-Io, Europa, Ganymede and Callisto-on each orbit. Initial results from the spacecraft's magnetometer have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede and possibly Io. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. We interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Electromagnetic induction requires eddy currents to flow within the moons, and our calculations show that the most probable explanation is that there are layers of significant electrical conductivity just beneath the surfaces of both moons. We argue that these conducting layers may best be explained by the presence of salty liquid-water oceans, for which there is already indirect geological evidence in the case of Europa.  相似文献   
56.
Differential hemispheric contributions to the perceptual phenomenon known as the McGurk effect were examined in normal subjects, 1 callosotomy patient, and 4 patients with intractable epilepsy. Twenty-five right-handed subjects were more likely to demonstrate an influence of a mouthed word on identification of a dubbed acoustic word when the speaker's face was lateralized to the LVF as compared with the RVF. In contrast, display of printed response alternatives in the RVF elicited a greater percentage of McGurk responses than display in the LVF. Visual field differences were absent in a group of 15 left-handed subjects. These results suggest that in right-handers, the two hemispheres may make distinct contributions to the McGurk effect. The callosotomy patient demonstrated reliable McGurk effects, but at a lower rate than the normal subjects and the epileptic control subjects. These data support the view that both the right and left hemisphere can make significant contributions to the McGurk effect.  相似文献   
57.
The human plasma high density lipoproteins (HDL) are a heterogeneous ensemble of five proteins associated with both neutral and polar lipids. The sequences of all five proteins are known. ApoA-I and apoA-II are the major protein components; apoC-I, apoC-II and apoC-III are the minor protein components. All these apoproteins spontaneously recombine with phospholipids to give stable lipid-protein complexes and freely exchange between the two major HDL subclasses, HDL2 and HDL3. In addition, ApoC-I, apoC-II, and apoC-III exchange between HDL and very low density lipoproteins. Furthermore, certain HDL apoproteins are activators for plasma enzymes that are important in lipid metabolism. ApoA-I and apoC-I activate lecithin/cholesterol acyltransferase; apoC-II is an activator of lipoprotein lipase. The regions of apoC-I and apoC-II that are involved in the activation of these enzymes have been localized with synthetic peptides. Studies of synthetic and native fragments of apoA-II, apoC-I, apoC-II, and apoC-III as well as model lipid-binding peptides have identified specific regions with structural features common to lipid-binding proteins. These special properties, which include helical potential, sequences with a critical amphipathic length, and high hydrophobicity of the nonpolar side of the amphipathic helix, are the determinants of HDL structure and metabolism.  相似文献   
58.
We studied 30 children, aged 4 to 12 years, undergoing elective circumcision, premedicated with midazolam 0.5 mg.kg-1 and atropine 0.02 mg.kg-1 by mouth. A modified postbox test and the coding component of the Wechsler intelligence scale (WISC-R) was used to assess the preoperative effect of premedication on psychomotor function. Mood and sedation were also scored and related to serum midazolam concentrations. The children showed a significant decline in psychomotor performance 30 and 60 minutes after premedication when compared with their best unmedicated performance recorded the previous evening. This decline in psychomotor performance was only weakly associated with serum midazolam concentrations (r = 0.1). The postbox toy ratio is a suitable measurement of psychomotor performance in children because of its simplicity and ease of use in the clinical environment, although it may suffer the "test-retest" limitations of similar types of assessment. The sedative and anxiolytic effects of midazolam provide a quiet environment for a smooth induction of anaesthesia.  相似文献   
59.
60.
The progressive loss of renal function in children with chronic renal failure (CRF) has a negative influence on their nutritional status and statural growth. Supportive therapies with 1-25 dihydroxy-vitamin D3, recombinant erythropoietin and growth hormone have significantly improved the biochemical and clinical features but the success of these therapies is largely related to an appropriate diet, with adequate protein/caloric intakes. Children more than adults have minimal protein requirements to avoid malnutrition and growth impairment FAO/WHO and RDA recommendations save as guidelines for a correct diet in children with CRF. Following these allowances leads to a "normoproteic" diet, with a protein intake which is often half the unrestricted one in Western European countries, but which is still likely to be not enough to protect against renal deterioration. Indeed the European Study Group for Nutritional Treatment of CRF in children failed to show a significant effect of diet on the mean decline of glomerular filtration rate over two years.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号