全文获取类型
收费全文 | 1127篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 14篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
能源动力 | 4篇 |
轻工业 | 1篇 |
无线电 | 21篇 |
一般工业技术 | 1篇 |
冶金工业 | 1080篇 |
自动化技术 | 2篇 |
出版年
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 9篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2004年 | 1篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 27篇 |
1998年 | 332篇 |
1997年 | 151篇 |
1996年 | 126篇 |
1995年 | 68篇 |
1994年 | 60篇 |
1993年 | 72篇 |
1992年 | 9篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1978年 | 3篇 |
1977年 | 29篇 |
1976年 | 77篇 |
1975年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有1128条查询结果,搜索用时 15 毫秒
991.
992.
CS Chang HC Lien HZ Yeh SK Poon SS Yang GH Chen 《Canadian Metallurgical Quarterly》1998,33(11):1164-1169
BACKGROUND: Transcatheter arterial chemoembolization (TACE) of the hepatic artery is frequently used in the treatment of inoperable hepatocellular carcinoma (HCC). TACE causes not only effective tumor tissue necrosis in patients with hepatoma but also adverse effects on extrahepatic abdominal organs. There are no published reports on the effect of TACE on the gastric myoelectric activity. In this study, using cutaneous electrogastrography (EGG), we evaluated the effect of TACE on gastric myoelectric activity in patients with HCC. METHODS: A total of 27 patients (24 men and 3 women, aged 22 to 78 years) with hepatoma, admitted for TACE, were included in this study. Furthermore, 28 patients (24 men and 4 women, aged 26 to 75 years), admitted for diagnostic angiography of the liver, served as the control group. Cutaneous EGG was performed before and after TACE or angiography. RESULTS: In the TACE group there were significant changes in dominant frequency (DF) and percentages of DF in the defined normal range, bradygastric range, and tachygastric range on post-meal EGG. On fasting EGG, only the dominant frequency and percentages of DF in the bradygastric range changed significantly. However, there was no correlation between the occurrence of nausea/vomiting and the degree of change in the EGG variables, during both fasting and postprandial states. In the control group there were no significant differences in EGG variables before and after angiography. CONCLUSIONS: TACE can affect gastric myoelectric activity in HCC patients. Nevertheless, the relationship between changes in myoelectric activity and the occurrence of gastrointestinal symptoms needs further investigation. 相似文献
993.
A case of viral transmission to the father of a newly vaccinated infant shows how the virtual disappearance of a once terrifying illness can obscure its recognition and how perplexing public health issues may arise when an invaluable vaccine is anything less than perfect. 相似文献
994.
Recent advances in cutaneous mast cell biology are briefly reviewed with special reference to our own studies on cultured human mast cells. Of note are the heterogeneity of mastocytosis, the important participation of mast cells in allergic inflammation by releasing cytokines and the inhibitory effect of histamine release from mast cells by phototherapy. It is also stressed that mast cells play a major role in tissue remodelling. These novel findings suggest that mast cells can no longer be regarded simply as cells that initiate immediate allergic reactions, but that they are responsible for various chronic inflammatory or immunological events through cytokine-dependent leucocyte recruitment. The regulation of mast cell activation should be a critical issue and, thus, a promising therapeutic approach in clinical dermatology. 相似文献
995.
S Glathe J Kervinen M Nimtz GH Li GJ Tobin TD Copeland DA Ashford A Wlodawer J Costa 《Canadian Metallurgical Quarterly》1998,273(47):31230-31236
The primary translation product of barley aspartic proteinase, phytepsin (EC 3.4.23.40), consists of a signal sequence, a propart, and mature enzyme forms. Here, we describe post-translational processing and activation of phytepsin during its transport to the vacuole in roots, as detected by using metabolic labeling and immunoprecipitation. After removal of the signal sequence, the glycosylated precursor of 53 kDa (P53) was produced and further processed to polypeptides of 31 and 15 kDa (P31 + P15) and, subsequently, to polypeptides of 26 and 9 kDa (P26 + P9), 45 min and 24 h after synthesis, respectively. The processing occurred in a late-Golgi compartment or post-Golgi compartment, because brefeldin A inhibited the processing, and P53 acquired partial endoglycosidase H resistance 30 min after synthesis, whereas P15 was completely resistant. The N-glycosylation inhibitor tunicamycin had no effect on transport, but the absence of glycans on P53 accelerated the proteolytic processing. Phytepsin was also expressed in baculovirus-infected insect cells. The recombinant prophytepsin underwent autoproteolytic activation in vitro and showed enzymatic properties similar to the enzyme purified from grains. However, a comparison of the in vitro/in vivo processing sites revealed slight differences, indicating that additional proteases are needed for the completion of the maturation in vivo. 相似文献
996.
WC Brown V Shkap D Zhu TC McGuire W Tuo TF McElwain GH Palmer 《Canadian Metallurgical Quarterly》1998,66(11):5406-5413
Protective immunity against the ehrlichial pathogen Anaplasma marginale has been hypothesized to require induction of immunoglobulin G2 (IgG2) antibody against outer membrane protein epitopes and coordinated activation of macrophages for phagocytosis and killing. In the present study, cell-mediated immune responses, including induction of IgG isotype switching, were characterized in calves immunized with purified outer membranes of the Florida strain of A. marginale. Importantly, these calves were subsequently shown to be protected upon experimental challenge with the Florida strain, and calves which developed the highest IgG2 titers were completely protected against infection. Peripheral blood mononuclear cells (PBMC) obtained after immunization proliferated strongly in response to both whole A. marginale homogenates and purified outer membranes, and this responsiveness persisted until the time of challenge. Responding cells were shown to be CD4(+) T cells, and CD4(+) T-cell lines cultured for 2 to 4 weeks also proliferated specifically in response to A. marginale and produced high titers of gamma interferon. The helper T-cell response included recognition of conserved epitopes, as PBMC proliferation was stimulated by the homologous Florida strain, four genetically distinct A. marginale strains, and Anaplasma ovis. The outer membrane proteins stimulating the PBMC responses in protected calves included major surface proteins (MSPs) MSP-1, MSP-2, and MSP-3, which were previously shown to induce partial protection against infection. These studies demonstrate, for the first time, potent helper T-cell responses in cattle protectively immunized with outer membranes against A. marginale challenge and identify three MSPs that are recognized by immune T cells. These experiments provide the basis for subsequent identification of the helper T-cell epitopes on MSP-1, MSP-2, and MSP-3 that are needed to evoke anamnestic antibody and effector T-cell responses elicited by protein or nucleic acid immunization. 相似文献
997.
Interviewer versus self-administered questionnaires in developing a disease-specific, health-related quality of life instrument for asthma 总被引:1,自引:0,他引:1
DJ Cook GH Guyatt E Juniper L Griffith W McIlroy A Willan R Jaeschke R Epstein 《Canadian Metallurgical Quarterly》1993,46(6):529-534
We wished to determine the extent to which respondents provided the same answers to a health-related quality of life (HRQL) questionnaire in self- and interviewer-administered forms. One hundred and fifty patients with asthma who were symptomatic or required treatment at least once a week, and had airway hyperresponsiveness to methacholine aerosol (PC20 < 8.0 mg/ml) participated. Patients completed a 152-item HRQL questionnaire in both interviewer and self-administered forms, separated by a 2-week interval, the order determined by random allocation. The percentage of items endorsed by the self-administered approach was significantly higher than that of the interviewer-administered approach overall (46.9 vs 35.8%) (p < 0.0001). The difference was consistent across all six domains; the absolute difference in the proportion of items endorsed varied from 8.9 to 12.3%. The intraclass correlations for the proportion of subjects endorsing an item was 0.84. Self- and interviewer-administered questionnaires yield very similar results in discriminating between subjects, but the self-administered version shows systematically greater HRQL impairment. 相似文献
998.
M Dubiel S Gudmundsson J Pirhonen GH Breborowicz K Marsal 《Canadian Metallurgical Quarterly》1997,10(4):272-276
OBJECTIVE: To evaluate the feasibility of implementing a physician based surveillance system of occupational respiratory diseases (PROPULSE) in Québec with regard to physician participation rate, characteristics of reported cases, and comparison with official statistics from the Workers' Compensation Board (WCB). METHODS: All chest physicians and allergists in Québec were asked to report suspected new cases of occupational respiratory diseases, on a monthly basis, between October 1992 and September 1993. For each case, personal information was collected and the physician's opinion on whether the condition was related to work was categorised as highly likely, likely, and unlikely. RESULTS: Of the 161 physicians initially approached, 68% participated. Physicians rated 48% of suspected cases as highly likely, 29% as likely, and 20% as unlikely. The most often reported diagnosis was asthma (63%), followed by diseases related to asbestos (16%). Silicosis was less frequent (5%) but it was reported for six workers under 40 of whom five were involved in sandblasting activities. The high proportion of cases of asthma probably reflects the increasing importance of this disease but may also reflect the different patterns of reporting among physicians with different expertise. The distribution of cases by diagnostic category is quite different between the PROPULSE system and that of the WCB (annual mean number of compensated cases during a four year period). Asthma and allergic alveolitis are more frequent in PROPULSE, reactive airways dysfunction syndrome are about the same in both systems, and other diseases are more frequent among compensated cases. The most frequent sensitising agents reported for asthma were the same in both systems (isocyanates, flour, and wood dust). 15% of the PROPULSE cases were not covered by the WCB, and therefore would not be found in the board's official statistics. CONCLUSIONS: A physician based reporting procedure can be implemented as part of a surveillance system to supplement data from other sources and thus provide a better understanding of the occurrence of occupational respiratory diseases. 相似文献
999.
PA Shlossman JS Manley AC Sciscione GH Colmorgen 《Canadian Metallurgical Quarterly》1997,14(8):449-456
Sophisticated neonatal transport has improved the safety of transporting preterm infants, but may not substitute for the benefits of in utero transport. To describe gestational age trends and assess differences in complications between maternal (in utero) and neonatal transports, we analyzed maternal and neonatal transports, over 3 years, to the only tertiary center in the region. Those who delivered between 24 and 34 weeks' gestation were included in the analysis. Gestational age trends for each complication are described, showing, in general, decreasing morbidity with gestational age in both groups. These trends were usually parallel, but not equal. A significantly greater mean neonatal intensive care unit (p = 0.003) and total length of stay (p = 0.006) as well as longer ventilator time (p = 0.01) and oxygen therapy exposure (p = 0.018) were noted in those transported neonatally. The incidence of respiratory distress syndrome (p < 0.001), bronchopulmonary dysplasia (p = 0.027), intraventricular hemorrhage (p = 0.041), intraventricular hemorrhage grades III and IV (p = 0.008), patent ductus arteriosus (p = 0.032), and mortality (p = 0.001) were all significantly greater among the neonatal transports. The differences were not significant for retinopathy of prematurity, hyperbilirubinemia, necrotizing enterocolitis, periventricular leukomalacia, and culture proven sepsis. Specialized neonatal transport and advanced neonatology techniques have not removed the significant advantage of decreased morbidity, mortality, and length of hospital intervention resulting from maternal (in utero) transport. 相似文献
1000.
G Ligtenberg PJ Blankestijn PL Oey GH Wieneke AC van Huffelen HA Koomans 《Canadian Metallurgical Quarterly》1997,95(9):2271-2276
BACKGROUND: Sudden hypotension in progressive hypovolemia or during hemodialysis is attributed to sudden inhibition of sympathetic activity. Critical ventricular underfilling seems responsible for this paradox, but it is unknown why the transition from sympathoactivation accompanying hypovolemia to sympathoinhibition is so abrupt. We studied whether brief fluctuation of sympathetic activity induced by cold pressor test (CPT) evokes sympathoinhibition if applied during low cardiac output. METHODS AND RESULTS: Fourteen healthy subjects underwent CPT, lower-body negative pressure (LBNP; -45 mm Hg for 60 minutes), or the combination thereof. CPT alone caused vasoconstriction and increased muscle sympathetic nerve activity, followed by uneventful relaxation. When applied during reduced cardiac output, tachycardia, and vasoconstriction induced by prior LBNP for 6 minutes, CPT again caused vasoconstriction, now followed by acute hypotension in 10 subjects, and was associated with vasorelaxation, relative bradycardia, and fall in muscle sympathetic nerve activity. Eight subjects also experienced acute LBNP-induced hypotension in the absence of CPT, but not until 17 +/- 6 minutes of LBNP. We also performed CPT before and in the final phase of hemodialysis in 8 patients. Before dialysis, the patients tolerated CPT uneventfully, but during hemodialysis, CPT provoked acute hypotension in 5 cases, showing similar withdrawal of vasoconstriction. CONCLUSIONS: This is the first study showing that brief cold stress, tolerated well in normal circulatory conditions, can provoke sudden sympathoinhibition and hypotension when applied during decreased cardiac output induced by LBNP or hemodialysis. We suggest that during conditions of a decreased cardiac output, subtle sympathetic relaxation such as follows cold stress triggers self-enhancing relaxation that cannot be controlled. 相似文献