全文获取类型
收费全文 | 590032篇 |
免费 | 8609篇 |
国内免费 | 2755篇 |
专业分类
电工技术 | 12181篇 |
综合类 | 2831篇 |
化学工业 | 93342篇 |
金属工艺 | 24797篇 |
机械仪表 | 19947篇 |
建筑科学 | 14699篇 |
矿业工程 | 4969篇 |
能源动力 | 15354篇 |
轻工业 | 47227篇 |
水利工程 | 7431篇 |
石油天然气 | 15886篇 |
武器工业 | 248篇 |
无线电 | 63080篇 |
一般工业技术 | 118700篇 |
冶金工业 | 96463篇 |
原子能技术 | 15102篇 |
自动化技术 | 49139篇 |
出版年
2022年 | 4340篇 |
2021年 | 6352篇 |
2020年 | 4677篇 |
2019年 | 5824篇 |
2018年 | 9836篇 |
2017年 | 10061篇 |
2016年 | 10403篇 |
2015年 | 6890篇 |
2014年 | 11348篇 |
2013年 | 27335篇 |
2012年 | 17237篇 |
2011年 | 22561篇 |
2010年 | 18495篇 |
2009年 | 20170篇 |
2008年 | 20396篇 |
2007年 | 20045篇 |
2006年 | 17415篇 |
2005年 | 15652篇 |
2004年 | 15109篇 |
2003年 | 15250篇 |
2002年 | 15345篇 |
2001年 | 14642篇 |
2000年 | 13142篇 |
1999年 | 12473篇 |
1998年 | 27844篇 |
1997年 | 20183篇 |
1996年 | 15780篇 |
1995年 | 12112篇 |
1994年 | 10927篇 |
1993年 | 10661篇 |
1992年 | 8388篇 |
1991年 | 8133篇 |
1990年 | 8021篇 |
1989年 | 7783篇 |
1988年 | 7498篇 |
1987年 | 6757篇 |
1986年 | 6539篇 |
1985年 | 7399篇 |
1984年 | 6706篇 |
1983年 | 6441篇 |
1982年 | 5783篇 |
1981年 | 5898篇 |
1980年 | 5637篇 |
1979年 | 5737篇 |
1978年 | 5663篇 |
1977年 | 6178篇 |
1976年 | 7685篇 |
1975年 | 5108篇 |
1974年 | 4903篇 |
1973年 | 4980篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
MA Steller KJ Gurski M Murakami RW Daniel KV Shah E Celis A Sette EL Trimble RC Park FM Marincola 《Canadian Metallurgical Quarterly》1998,4(9):2103-2109
Human papillomavirus (HPV) infection has been causally associated with cervical cancer. We tested the effectiveness of an HLA-A*0201-restricted, HPV-16 E7 lipopeptide vaccine in eliciting cellular immune responses in vivo in women with refractory cervical cancer. In a nonrandomized Phase I clinical trial, 12 women expressing the HLA-A2 allele with refractory cervical or vaginal cancer were vaccinated with four E786-93 lipopeptide inoculations at 3-week intervals. HLA-A2 subtyping was also performed, and HPV typing was assessed on tumor specimens. Induction of epitope-specific CD8+ T-lymphocyte (CTL) responses was analyzed using peripheral blood leukapheresis specimens obtained before and after vaccination. CTL specificity was measured by IFN-gamma release assay using HLA-A*0201 matched target cells. Clinical responses were assessed by physical examination and radiographic images. All HLA-A*0201 patients were able to mount a cellular immune response to a control peptide. E786-93-specific CTLs were elicited in 4 of 10 evaluable HLA-A*0201 subjects before vaccination, 5 of 7 evaluable HLA-A*0201 patients after two vaccinations, and 2 of 3 evaluable HLA-A*0201 cultures after all four inoculations. Two of three evaluable patients' CTLs converted from unreactive to reactive after administration of all four inoculations. There were no clinical responses or treatment toxicities. The ability to generate specific cellular immune responses is retained in patients with advanced cervical cancer. Vaccination with a lipidated HPV peptide epitope appears capable of safely augmenting CTL reactivity. Although enhancements of cellular immune responses are needed to achieve therapeutic utility in advanced cervical cancer, this approach might prove useful in treating preinvasive disease. 相似文献
152.
153.
154.
E Arvat R Giordano J Ramunni G Arnaldi A Colao R Deghenghi G Lombardi F Mantero F Camanni E Ghigo 《Canadian Metallurgical Quarterly》1998,83(12):4207-4211
We previously reported that in Cushing's disease (CD) the ACTH- and cortisol (F)-releasing activity of Hexarelin (HEX), a GH secretagogue, is exaggerated with respect to that in normal subjects and is higher than that of human CRH (hCRH), but it is absent in Cushing's syndrome. Our aim was to extend the study about the effects of HEX (2.0 microg/kg, iv) on ACTH and F secretion in 21 patients with CD (3 men and 18 women, 16-68 yr old). Based on magnetic resonance imaging, 15 CD patients had pituitary microadenoma, and 6 had macroadenoma. The results in CD patients were compared with those in 27 normal age-matched controls (NS; 10 men and 17 women, 24-69 yr old). Basal ACTH and F levels in CD were similar in patients with microadenom (mean+/-SEM, 78.3+/-7.2 pg/mL and 237.1+/-23.6 microg/L, respectively) and macroadenoma (57.4+/-9.0 pg/mL and 196.9+/-20.1 microg/L, respectively) and were higher (P < 0.001) than those in NS (17.7+/-2.0 pg/mL and 115.3+/-6.7 microg/L, respectively). In microadenoma CD patients, HEX induced marked ACTH and F increases (delta peak, mean+/-SEM: 261.2+/-77.6 pg/mL and 226.1+/-87.2 microg/L, respectively), which were higher (P < 0.04) than those induced by hCRH (45.6+/-16.9 pg/mL and 84.6+/-25.7 microg/L, respectively). Moreover, in microadenoma CD patients, the ACTH and F responses to HEX were higher (P < 0.001) than those in NS (18.5+/-4.0 pg/mL and 36.1+/-6.8 microg/L, respectively). In macroadenoma CD patients, HEX induced a slight, but significant increase (P < 0.02) in ACTH and F levels (33.9+/-18.0 pg/mL and 89.6+/-34.3 microg/L, respectively), which was not significantly different from that elicited by hCRH (20.0+/-7.0 pg/mL and 54.8+/-21.3 microg/L, respectively). In macroadenoma CD patients, the ACTH and F responses to HEX and hCRH were, in turn, similar to those in NS. In conclusion, our findings demonstrate that the ACTH and F hyperresponsiveness to HEX is present in Cushing's disease with micro-, but not macro- ACTH-secreting pituitary adenoma. This finding agrees with other evidence pointing toward differences in the hormonal behavior between micro- and ACTH-secreting pituitary macroadenomas. 相似文献
155.
156.
A systematic and straightforward procedure is developed for the synthesis and analysis of transformer-isolated power converters. The procedure can be used to determine the ranges of duty-ratio over which the transformer-isolated power converters of a given class can be operated without transformer saturation. The procedure can also be used to study the dependence of the power converter switch stresses on duty-ratios. This information is useful in the selection of the transformer-isolated power converter most suitable for a given application and in the design of this power converter with minimum switch stresses, high power density, and low cost 相似文献
157.
158.
159.
160.
OBJECTIVES: To assess that neuromuscular relaxation onset of the adductor pollicis (AP) is related to neuromuscular stimulation rate. To assess that train-of-four (TOF) at 0.05 Hz is a more accurate indicator of optimal tracheal intubation time and conditions, than TOF at 0.08 Hz. STUDY DESIGN: Prospective, comparative, randomized double-blind study. PATIENTS: Forty adults, physical class ASA 1 or 2, undergoing general anaesthesia with tracheal intubation were allocated to two groups (n = 20) according to the sequence of stimulation of the AP: either TOF at 0.05 Hz (test group) or TOF at 0.08 Hz (control group). METHODS: Induction of anaesthesia was achieved with thiopentone, fentanyl and vecuronium (0.1 mg.kg-1). Neuromuscular monitoring was obtained with force displacement transducers attached to each AP. Tracheal intubation was performed once AP muscular response obtained with TOF at 0.05 Hz for test group and TOF at 0.08 Hz for control group was abolished. Results are expressed as mean +/- SEM. Fisher exact test was used for intubation conditions comparison. Curarization time between groups was compared with unpaired Student's t test (P < 0.05 accepted). RESULTS: TOF with 0.05 Hz stimulation significantly increased curarization time: 217 +/- 7 versus 162 +/- 6 s (P < 0.001). Intubation conditions were excellent in 95% and good in 5% of patients in the study group, compared to 15 and 40% in the control group, respectively (P < 0.01) in 45% of the control group patients coughing at intubation occurred. CONCLUSION: Low stimulation rate (TOF at 0.05 Hz) of AP is a reliable technique to determine the appropriate intubation time for patients paralyzed with vecuronium. 相似文献