全文获取类型
收费全文 | 1803篇 |
免费 | 7篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 38篇 |
金属工艺 | 5篇 |
机械仪表 | 4篇 |
建筑科学 | 14篇 |
矿业工程 | 3篇 |
能源动力 | 5篇 |
轻工业 | 25篇 |
水利工程 | 4篇 |
无线电 | 12篇 |
一般工业技术 | 38篇 |
冶金工业 | 1616篇 |
自动化技术 | 39篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 17篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 44篇 |
1998年 | 474篇 |
1997年 | 279篇 |
1996年 | 192篇 |
1995年 | 112篇 |
1994年 | 88篇 |
1993年 | 90篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 18篇 |
1989年 | 32篇 |
1988年 | 26篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 18篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 19篇 |
1980年 | 22篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 47篇 |
1976年 | 105篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1955年 | 2篇 |
1923年 | 1篇 |
排序方式: 共有1810条查询结果,搜索用时 15 毫秒
1.
2.
3.
OBJECTIVE: To determine the characteristics and long-term outcome of radiation-induced thyroid cancer in children. DESIGN: Retrospective review of a cohort of 4296 irradiated patients who received childhood radiation treatment to the head and neck area at the same hospital. PATIENTS: Forty-one children who were younger than 20 years when thyroid cancer developed in them and 77 adults in whom thyroid cancer developed. All 118 cases were diagnosed before 1974 and were followed up for a median of 19.4 years. RESULTS: Children presented with clinically palpable lymph nodes more often than adults (30.7% vs 15.1%, P = .05) and had more recurrences (39% vs 16%, P = .05). Despite these frequent recurrences, only one patient (an adult) died of thyroid cancer. Seventy percent of the recurrences occurred during the first 10 years of follow-up, but recurrences continued after 20 years. The adults had previously identified factors that predicted the risk of recurrences, but none could be identified in the children. CONCLUSION: The presentation and relatively good outcome of radiation-induced thyroid cancer in children is similar to that in nonirradiated children. Frequent and late recurrences call for lifelong follow-up. 相似文献
4.
NV Zheleznova SL Mukomolov AB Zhebrun FS Noskov II Malkova EP Shargorodskaia AD Al'tshte?n VA Pliutnikova IN Lavrent'eva NN Ptichnikova 《Canadian Metallurgical Quarterly》1996,(5):49-53
The use of a recombinant poxvirus (RPV) strain, expressing HBsAg in the process of reproduction in different bioreactor systems under stationary and bioreactor conditions of cultivation, made it possible to obtain highly purified HBsAg. The identity and purity of HBsAg was confirmed by the analysis of its amino acid composition, SDS electrophoresis in polyacrylamide gel, electron microscopy and high-performance liquid chromatography. Good prospects of the use of RPV-expressed gene engineering HBsAg as the basis vaccines against hepatitis B was demonstrated in 10 experimental batches of vaccine. All batches of the preparation had pronounced immunogenicity and were safe and nontoxic in animal experiments. The ID50 of experimental batches did not exceed 211 ng/ml, which, according to the data of comparative experiments, was lower than, or equal to, corresponding values of analogous foreign commercial preparations, based on plasma or yeast HBsAg. 相似文献
5.
6.
7.
SW Qian JK Burmester PD Sun A Huang DJ Ohlsen L Suardet KC Flanders D Davies AB Roberts MB Sporn 《Canadian Metallurgical Quarterly》1994,33(40):12298-12304
Transforming growth factor-beta (TGF-beta) is a potent regulator of cell growth and differentiation. On the basis of the crystal structure of TGF-beta 2, we have designed and synthesized two mutant TGF-beta s, TGF-beta 1 (71 Trp) and TGF-beta 1 (delta 69-73). Although both of these molecules inhibited the growth of Mv1Lu mink lung epithelial cells and LS1034 colorectal cancer cells, which are affected equally by TGF-beta 1 and TGF-beta 2, TGF-beta 1 (delta 69-73) was much less potent than TGF-beta 1 or TGF-beta 1 (71 Trp) at inhibiting the growth of LS513 colorectal cancer cells which are growth-inhibited by TGF-beta 1 but not TGF-beta 2. Both TGF-beta 1 (71 Trp) and TGF-beta 1 (delta 69-73) increased levels of mRNAs for fibronectin and plasminogen activator inhibitor with Mv1Lu cells, whereas only TGF-beta 1 (71 Trp) and not TGF-beta 1 (delta 69-73) up-regulated the mRNA level of carcinoembryonic antigen in LS513 cells. The expression level of carcinoembryonic antigen mRNA in LS1034 cells was not altered by either wild-type or mutant TGF-beta s. Receptor labeling experiments demonstrated that TGF-beta 1 (71 Trp) bound with high affinity to the cell-surface receptors of Mv1Lu, LS1034, and LS513 cells while TGF-beta 1 (delta 69-73) bound effectively to the receptors of Mv1Lu and LS1034 cells but much less to the receptors on LS513 cells.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
8.
PR Bennett R Warwick J Vaughan H Chana A Lubenko NM Fisk 《Canadian Metallurgical Quarterly》1994,101(3):246-249
OBJECTIVE: To assess the effectiveness of a newly developed individualised birthweight ratio (IBR), which corrects for physiological birthweight determinants, in identifying infants at risk from the complications of macrosomia. DESIGN: Prospective observational study. SETTING: Obstetric unit, Nottingham City Hospital. SUBJECTS: 2835 women delivered between December 1991 and July 1992 and the infants of 624 of these, selected by virtue of their birthweight for gestation and IBR centile positions. MAIN OUTCOME MEASURES: Skinfold thickness and ponderal index measurements, operative delivery, shoulder dystocia, fetal trauma, impaired glucose tolerance. RESULTS: Using an IBR above the 90th centile as a cut off results in 2.4% of infants being reclassified as normally grown and 3.1% are reclassified as large. The IBR does not result in the identification of any more infants with abnormal ponderal indices or skinfold thicknesses than birthweight for gestation. It does, however, identify more of the infants at risk of operative delivery, shoulder dystocia, fetal trauma and impaired glucose tolerance. CONCLUSION: The IBR significantly improves upon birthweight for gestation in identifying infants who suffer from the complications of relative macrosomia. 相似文献
9.
10.
K Okano S Wu X Huang CJ Pirola H Juppner AB Abou-Samra GV Segre K Iwasaki JA Fagin TL Clemens 《Canadian Metallurgical Quarterly》1994,135(3):1093-1099