全文获取类型
收费全文 | 1993篇 |
免费 | 0篇 |
专业分类
化学工业 | 7篇 |
金属工艺 | 2篇 |
轻工业 | 2篇 |
一般工业技术 | 3篇 |
冶金工业 | 1976篇 |
自动化技术 | 3篇 |
出版年
2021年 | 1篇 |
2011年 | 2篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2003年 | 4篇 |
1999年 | 71篇 |
1998年 | 710篇 |
1997年 | 386篇 |
1996年 | 230篇 |
1995年 | 116篇 |
1994年 | 111篇 |
1993年 | 116篇 |
1992年 | 16篇 |
1991年 | 21篇 |
1990年 | 8篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1978年 | 1篇 |
1977年 | 32篇 |
1976年 | 66篇 |
1975年 | 4篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1993条查询结果,搜索用时 31 毫秒
201.
RR Frazier ES Millican SK Watson NJ Oldroyd RL Sparkles KM Taylor S Panchal L Bark CP Kimpton PD Gill 《Canadian Metallurgical Quarterly》1996,17(10):1550-1552
The Applied Biosystems (ABI) Prism 377 DNA sequencer has been evaluated in an attempt to increase the throughput of samples for short tandem repeat (STR) analysis, in both forensic casework and the UK National Criminal Intelligence DNA Database. The gel system assessed consisted of 0.2 mm, 4% acrylamide 6 M urea gels, with a well-to-read distance of 36 cm. Gels were run at a constant voltage of 3 kV and constant temperature of 51 degrees C. The run time of our second generation multiplex (SGM) STR system was achieved in less than 2 h. Rigorous validation has been performed on the instrument hardware and software. Complete resolution of 1 base differences was obtained, up to and beyond 350 bases; sizing precision across gels was more than 2-fold higher than the 373A and the sensitivity was increased by one third. 相似文献
202.
Mde L Chauffaille RM Valério CM Diniz MM Sim?es S Enokihara N Michalany KV Ferreira JA Martinez KM Hassun AN Atallah J Kerbauy 《Canadian Metallurgical Quarterly》1998,116(1):1625-1628
The authors present a rare case of Langerhans cell histiocytosis in a 31 year old female patient with vulvar, peri-anal and oral lesions, diabetes insipidus, pulmonary skin and bone infiltrations. Skin biopsy immunohistochemistry presented positive S100 protein and vimentin, but the diagnosis was done with the demonstration of Birbeck granules with electronic microscopy. The treatment was based on systematical chemotherapy although vulvar lesion has a bad response to chemotherapy. 相似文献
203.
This paper examines the sexual risk behavior of female injecting drug users who participated in a 4 year longitudinal study. Both HIV+ and HIV- women showed increases in monogamy, decreases in the frequency of unprotected vaginal/anal sex, and decreases in a risk index score throughout the study. HIV+ women had fewer occasions of unprotected sex than HIV-. However, a substantial proportion of the sample continued to engage in unprotected sex. Among the HIV+ women, depressed mood was significantly related to abstinence and to fewer occasions of unprotected sex, but CD4, medical symptoms, neurological impairment, and memory test performance were not associated with sexual risk behavior. 相似文献
204.
KM Casteels CA Gysemans M Waer R Bouillon JM Laureys J Depovere C Mathieu 《Canadian Metallurgical Quarterly》1998,47(7):1033-1037
The purpose of the study was to evaluate the association between smoking during pregnancy and preterm birth. The overall rate of preterm delivery was 4.3%. Smokers had a 40% higher risk of preterm birth compared to non-smokers. A dose response relationship was found between smoking and risk of preterm birth. Adjustment for women's height, pre-pregnant weight, age of the mother, marital status, education, occupational status, and alcohol intake did not change the results. Among women with an intake of less than 400 mg of caffeine per day no difference in the risk of preterm birth between smokers and non-smokers was found. However, among women with an intake of more than 400 mg of caffeine per day, the risk of preterm birth was increased almost threefold among smokers compared to non-smokers. Furthermore, among women with a high intake of caffeine a dose response relationship was found between smoking and risk of preterm delivery. 相似文献
205.
MS Wolin CA Davidson PM Kaminski RP Fayngersh KM Mohazzab-H 《Canadian Metallurgical Quarterly》1998,63(7):810-816
Nitric oxide has several signalling mechanisms that can potentially control force generation by vascular smooth muscle. Some of these mechanisms include the stimulation of cGMP production by the soluble heme-containing form of guanylate cyclase (sGC), inhibition of mitochondrial respiration, and the modulation of vasoactive mediator release by the endothelium. Reactive O2 species (ROS) can also regulate force generation by vascular smooth muscle through mechanisms including the stimulation of production of vasoactive prostaglandins, the stimulation of sGC by catalase-mediated metabolism of H2O2 and inhibition of sGC activation by superoxide, the activation of protein kinase C, and the modulation of mediator release from the endothelium. Interactions between NO and ROS signalling mechanisms result in additional processes which modulate vascular force generation. For example, NO-elicited stimulation of sGC can be attenuated by superoxide, and this results in the formation of peroxynitrite (ONOO-). However, high levels of NO result in a ONOO- and thiol dependent formation of a species which regenerates NO in a time-dependent manner. It appears that NO inhibits catalase through an O2 and superoxide dependent process which results in inhibition of relaxation mediated by H2O2-elicited stimulation of sGC. Furthermore, evidence exists suggesting additional signalling mechanisms resulting from interactions between regulatory systems involving NO and ROS which appear to be important in control of vascular force generation in pathophysiological states. 相似文献
206.
KM McRoberts BP Meloni UM Morgan R Marano N Binz SL Eriandsen SA Halse RC Thompson 《Canadian Metallurgical Quarterly》1996,82(5):711-718
Following the first report of avian Giardia infection in Australia, isolates of the parasite recovered from naturally infected straw-necked ibis (Theskiornis spinicollis) were characterized using median body morphology, scanning electron microscopy, multilocus enzyme electrophoresis, random amplified polymorphic DNA (RAPD), and small subunit ribosomal RNA (SSU-rRNA) analyses. Results were compared with Giardia from other birds and mammals, and the extent of genetic diversity between a range of ibis isolates collected in Western Australia was determined. The ibis isolates of Giardia were genetically relatively homogeneous, which is in contrast to the extensive genetic heterogeneity often displayed by mammalian Giardia isolates. Morphologically, Giardia from ibis were similar to Giardia ardeae although they differed genetically and by the fact that the ibis isolates could not be established in in vitro culture. Sequence data of the DNA coding for the SSU-rRNA found a 96% homology between the ibis isolates from Western Australia and G. ardeae, suggesting that they represent distinct strains of the same species. In contrast, the ibis isolates were genetically and morphologically very different than Giardia duodenalis and Giardia muris from mammals. 相似文献
207.
208.
209.
AM Antonov KM Chernov NA Iaitski? NN Grinenko MV Grigor''eva 《Canadian Metallurgical Quarterly》1998,157(5):144-145
Breech presentation occurs in 3-5% of deliveries and can be managed by either a trial of vaginal breech delivery (TOVBD), external cephalic version (ECV) or Caesarean section. A postal questionnaire was completed by 82% of Scottish consultant obstetricians and revealed wide variations in practice. Eighteen percent never offered ECV. Among those who did consensus was lacking on some contraindications. One-quarter sometimes performed ECV before 37 weeks gestations despite the possibility of spontaneous version. Only 70% restricted ECV to one or more designated operators thereby maintaining levels of expertise. Variations were demonstrated in the use of tocolytics, and pre and post procedure investigations. Following failed ECV 28% considered a repeat attempt and 56% a TOVBD. TOVBD was not offered as first line management by one-fifth of respondents. Those who did varied in the pre-procedure investigations performed. Guidelines are required to ensure safe, consistent practice and avoid unnecessary Caesarean sections. 相似文献
210.