全文获取类型
收费全文 | 1618篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 19篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
矿业工程 | 3篇 |
轻工业 | 5篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 20篇 |
一般工业技术 | 11篇 |
冶金工业 | 1526篇 |
自动化技术 | 26篇 |
出版年
2021年 | 1篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2013年 | 19篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 41篇 |
1998年 | 484篇 |
1997年 | 269篇 |
1996年 | 187篇 |
1995年 | 106篇 |
1994年 | 70篇 |
1993年 | 118篇 |
1992年 | 6篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 23篇 |
1978年 | 2篇 |
1977年 | 34篇 |
1976年 | 89篇 |
1975年 | 3篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1621条查询结果,搜索用时 10 毫秒
71.
72.
73.
Although a curable malignancy, testis cancer and its treatment have unique associated morbidities that largely affect reproductive dysfunction. In this focused review, the factors that contribute to infertility in men with testis cancer are outlined. The treatment-specific risks to fertility that accompany cancer management are also discussed. Contemporary methods of overcoming infertility in testis cancer patients are addressed, and several exciting and promising experimental approaches to the preservation or restoration of fertility for men with testis cancer are presented. 相似文献
74.
75.
Midwestern populations of Coquillettidia perturbans (Walker) and Anopheles quadrimaculatus (Say) were tested for their ability to transmit Cache Valley virus (CV), a recognized human and animal pathogen. Field-collected mosquitoes were fed artificial blood meals containing 5.2-6.2 log10 pfu/ml of CV. After 9-23 d at 28 degrees C, 75-93% of blood-fed Cq. perturbans had disseminated infections and 6-62% transmitted the virus to suckling mice. However, when infected with a lower virus titer (3.3 log10 pfu/ml), only 10-36% of the mosquitoes had disseminated infections and 0-10% transmitted the virus to suckling mice. A similar infection rate (21%) was observed in Cq. perturbans fed on viremic (3.2 log10 pfu/ml) hamsters. An. quadrimaculatus were infected (81-100%) by both doses used, with transmission rates ranging from 13-67% after 16-23 d of incubation. Transmission rates for the laboratory strain An. quadrimaculatus SAVANNAH ranged from 20 to 33% after 7-14 d of incubation. Our data show that although An. quadrimaculatus is more susceptible to CV infections than Cq. perturbans, both mosquito species could be involved in the midwestern transmission cycle of the virus. 相似文献
76.
PR Evans 《Canadian Metallurgical Quarterly》1976,2(6040):839-841
About one person in four or five is conscious that scratching an irritation may produce an itch elsewhere. The sensation is well localised, comes and goes quickly, and recurs when scratching is repeated a short while later. Scratch and referred itch are ipsilateral; scratching the site of the referred itch does not cause the original spot to itch. Scatching face, palms, or soles does not produce referred itching. Different people stimulated in the same region do not necessarily feel referred itch in the same place. The mechanism of the phenomenon is unknown, though it may be thalamic. 相似文献
77.
78.
DP Stoker ML Perl G Abrams AR Baden T Barklow BA Barnett AM Boyarski J Boyer PR Burchat F Butler JM Dorfan GJ Feldman G Gidal G Hanson BD Harral K Hayes D Herrup JE Hylen WR Innes JA Jaros JA Kadyk D Karlen SR Klein AJ Lankford BW LeClaire M Levi V Lüth JA Matthews RA Ong K Riles PC Rowson DR Wood 《Canadian Metallurgical Quarterly》1989,39(7):1811-1824
79.
The immunoglobulin M antibody response to the lipoteichoic acid (LTA) of Staphylococcus aureus ATCC 6538P was examined by a procedure in which erythrocytes sensitized with periodate-activated LTA were used for the detection of immunoglobulin M-producing plaque-forming cells LTA-specific plaque-forming cells were first detected 2 days after immunization with heat-killed bacterial cells, and maximal numbers of plaque-forming cells, mostly of the immunoglobulin M class rather than the immunoblogulin G or immunoglobulin A class, were attained by day 4; specificity for LTA was affirmed by plaque inhibition tests. No plaque-forming cells were found in mice given isolated LTA over a 10,000-fold range of immunizing doses. Mice pretreated with a carrier known to activate thymus-derived helper lymphocytes produced a plaque-forming cell response to LTA only when immunized with LTA bound to the same carrier. This suggests that carrier-specific thymus-derived cells are needed to initiate an antibody response to poorly immunogenic LTA. Since an antibody response can be elicited in mice given heat-killed cells, other cell wall and/or cell membrane constituents may play an important role as immunologically active carriers for this antigen. 相似文献
80.
A Reber PR Huber W Ummenhofer CM Gürtler C Zurschmiede J Drewe M Schneider 《Canadian Metallurgical Quarterly》1998,42(9):1050-1056
BACKGROUND: Both melatonin and anaesthetics have been shown to affect sleep and behaviour. The effect of general anaesthesia on circulatory melatonin has not been reported, but anaesthetic-related alterations in hormone profiles are known. We hypothesize that differences in recovery from anaesthesia may be associated with differences in circulatory melatonin levels because of melatonin's sedative effect in humans. METHODS: The influences of general anaesthesia and surgery on circulating melatonin, prolactin, and cortisol concentration were investigated in 32 female patients scheduled for elective gynaecological surgery to study differences in hormone profiles and responses during anaesthesia and the recovery period. Patients were randomly assigned to one of two groups. General anaesthesia was induced with either thiopentone/fentanyl (Group 1: n = 16) or propofol/fentanyl (Group 2: n = 16). Maintenance of anaesthesia was achieved with either isoflurane (0.8-1.0 vol%)/fentanyl (Group 1) or propofol (6 mg.kg-1.h-1)/fentanyl (Group 2) with a N2O/O2 flow ratio of 2:1 in both groups. During anaesthesia, patients' eyes were carefully taped shut to prevent light effects. Blood samples were taken before and after premedication, immediately before induction of anaesthesia, every 15 min during anaesthesia, and hourly in the recovery room for 8 h. The control group consisted of 6 healthy women who were not subjected to surgery, but who were in a similar environment, including light conditions, as the study groups. RESULTS: Isoflurane and propofol anaesthesia as well as darkness elicited elevated plasma melatonin levels that persisted in the recovery period in patients anaesthetized with isoflurane, but gradually decreased during the recovery of patients anaesthetized with propofol. Circulating prolactin and cortisol values were also elevated during anaesthesia and had similar decreases during the recovery period. CONCLUSION: Higher plasma levels of melatonin during the recovery period following isoflurane anaesthesia may, in part, explain increased sedation in these patients compared with patients who received propofol anaesthesia. However, the relationship between recovery from anaesthesia and plasma melatonin levels may not be simple and straightforward. 相似文献