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   2435篇
  免费   2篇
综合类   2篇
化学工业   3篇
机械仪表   1篇
能源动力   1篇
轻工业   1篇
石油天然气   1篇
一般工业技术   4篇
冶金工业   2422篇
自动化技术   2篇
  2022年   1篇
  2019年   1篇
  2018年   2篇
  2016年   1篇
  2009年   1篇
  2007年   1篇
  2005年   1篇
  2004年   1篇
  2003年   3篇
  2000年   1篇
  1999年   70篇
  1998年   742篇
  1997年   415篇
  1996年   298篇
  1995年   149篇
  1994年   128篇
  1993年   143篇
  1992年   13篇
  1991年   23篇
  1990年   25篇
  1989年   21篇
  1988年   24篇
  1987年   21篇
  1986年   16篇
  1985年   13篇
  1984年   1篇
  1983年   7篇
  1982年   14篇
  1981年   14篇
  1980年   23篇
  1979年   3篇
  1978年   9篇
  1977年   61篇
  1976年   176篇
  1975年   4篇
  1973年   2篇
  1965年   1篇
  1964年   3篇
  1963年   1篇
  1960年   1篇
  1955年   3篇
排序方式: 共有2437条查询结果,搜索用时 15 毫秒
91.
In October 1996, dermatologists commemorated the centenary of the Patch test that Jadassohn had developed in 1896 at Breslau. A great amount of scientific information came to light in the following years due to progress in immunology applied to dermatology. To consider the most important recent advances in the field of contact allergic dermatitis, it is necessary to recognise the role of adhesion molecules specific for antigen presenting dendritic cells, also keratinocytes as antigen presenting cells, the importance of CD8 cells, IL10, IL12 and IL1 and their role in modulation of the contact allergy reaction. The chemistry of haptens should lead to a decision as to whether a new molecule is allergic or not, as well as the different possibilities of bonding to form sensitizing complexes. Epidemiology and the present development of epicutaneous tests are at the centre of studies that are mentioned in this general review.  相似文献   
92.
The mechanism of uptake of human immunodeficiency virus-1 (HIV-1) into alveolar macrophages (AM), freshly isolated blood monocytes (MN), and cultured MN (CM) was investigated focusing on the role of CD4 and of surfactant-associated protein A (SP-A). By radioimmunoassay which obviated the problems of auto- and nonspecific fluorescence of more differentiated macrophages, each of the macrophage populations studied expressed CD4. Semiquantitative polymerase chain reaction was performed to assess uptake of HIV-1(JR-FL) into cells. OKT4a (directed against CD4) blocked uptake of HIV-1 into CM, AM, and MN by 67 to 100%. OKT4 (directed against another epitope of CD4) had a smaller and less consistent effect (0-90%), and control antibodies showed minimal effects and only at supersaturating concentrations. SP-A had no effect on uptake of HIV-1 into AM. SP-A also had no consistent effect on production of HIV-1(JR-FL) by AM infected in vitro (p24 antigen ELISA). Thus CD4 is the major receptor for HIV-1 in mononuclear phagocytes, including AM, and SP-A does not modulate entry.  相似文献   
93.
94.
The clinical features of acute chlorine gas inhalation, and its management are reviewed. Current medical views on the chronic effects of an acute overwhelming exposure on lung function (reactive airways dysfunction syndrome), and the more controversial field of lung disease secondary to repeated inhalations of lower concentrations of chlorine gas are discussed.  相似文献   
95.
96.
Five multiparous Holstein cows in midlactation that were fitted with ruminal and duodenal cannulas were used in a 3 x 5 incomplete Latin square. The objective of this study was to examine the effects on nutrient digestion of wheat processing and method of tallow addition to the diets of lactating dairy cows. Diets consisted of 45% forage and 55% concentrate, and each diet contained 20% wheat and 2% tallow (as-fed basis). Treatments were dry-rolled wheat with tallow added to the concentrate, steam-rolled wheat with tallow added to the concentrate, and steam-rolled wheat with tallow added first to the wheat. The dry matter intake; digestion of starch, fiber, and fatty acids; ammonia N concentration; and molar proportions of volatile fatty acids in ruminal fluid were not affected by treatments. The apparent digestibility in the total tract of organic matter and nitrogenous compounds was significantly higher for the steam-rolled treatment with tallow added first to the wheat. Mean ruminal fluid pH was similar across treatments; however, cows fed the diet containing steam-rolled wheat with tallow added first to the wheat had the smallest pH change from 0 to 2 h postfeeding. Milk yield did not differ, regardless of cow diet. Method of tallow addition had marked effects on the apparent digestibility of organic matter and N in the total tract of lactating dairy cows.  相似文献   
97.
Successive magnetic evoked potentials (MEPs) concern varying motor neurons. We investigated whether this MEP-specific source of variability depends on electrode site and size. Amplitude variability (standard deviation) was largest over the center of the hypothenar muscles. Latencies were longer at distal and proximal sites than at the center site. Large electrodes (10 cm2) did not decrease this source of amplitude variability compared with EEG electrodes, in contrast to other sources of variability.  相似文献   
98.
We have measured by indirect ELISA the binding of neutralizing and non-neutralizing anti-lactate dehydrogenase-elevating virus (LDV) polyclonal and monoclonal antibodies to synthetic peptides representing unmodified hydrophilic segments of LDV proteins. Using this method a single neutralization epitope has been shown to be located in the very short (about 30 amino acid long) ectodomain of the primary envelope glycoprotein, VP-3P, encoded by ORF 5. Although the neutralization epitopes of neuropathogenic and non-neuropathogenic LDVs differ slightly in amino acid sequences, the neutralizing antibodies bind strongly to the epitopes of both groups of viruses. However, the neutralization epitopes of neuropathogenic and non-neuropathogenic LDVs are associated with different numbers of polylactosaminoglycan chains (1 and 3, respectively) which may affect the binding of neutralizing antibodies to the virions of these LDVs. The ELISA using synthetic peptides containing the neutralization epitope provides a novel, rapid, sensitive, and inexpensive method for quantitating LDV neutralizing antibodies in infected mice.  相似文献   
99.
An arginine to glutamine missense mutation at position 403 of the beta-cardiac myosin heavy chain causes familial hypertrophic cardiomyopathy. Here we study mice which have this same missense mutation (alphaMHC403/+) using an isolated, isovolumic heart preparation where cardiac performance is measured simultaneously with cardiac energetics using 31P nuclear magnetic resonance spectroscopy. We observed three major alterations in the physiology and bioenergetics of the alphaMHC403/+ mouse hearts. First, while there was no evidence of systolic dysfunction, diastolic function was impaired during inotropic stimulation. Diastolic dysfunction was manifest as both a decreased rate of left ventricular relaxation and an increase in end-diastolic pressure. Second, under baseline conditions alphaMHC403/+ hearts had lower phosphocreatine and increased inorganic phosphate contents resulting in a decrease in the calculated value for the free energy released from ATP hydrolysis. Third, hearts from alphaMHC403/+ hearts that were studied unpaced responded to increased perfusate calcium by decreasing heart rate approximately twice as much as wild types. We conclude that hearts from alphaMHC403/+ mice demonstrate work load-dependent diastolic dysfunction resembling the human form of familial hypertrophic cardiomyopathy. Changes in high-energy phosphate content suggest that an energy-requiring process may contribute to the observed diastolic dysfunction.  相似文献   
100.
The multiple chemical sensitivity syndrome (MCS) is a novel constellation of symptoms in environmental medicine that has been extensively described and commented on in the USA. The main features of this syndrome are: multiple symptoms in different organ systems triggered by a variety of chemical substances, with relapses and exacerbations under certain precipitating circumstances at very low levels which do not cause any reactions in the population at large. There are no lab markers or specific investigative findings. This paper describes the historical development of the term MCS, its diagnostic criteria and pathophysiological aspects using 10 patient histories from our hospital.  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