全文获取类型
收费全文 | 1602篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 4篇 |
化学工业 | 167篇 |
金属工艺 | 16篇 |
机械仪表 | 23篇 |
建筑科学 | 24篇 |
矿业工程 | 3篇 |
能源动力 | 16篇 |
轻工业 | 68篇 |
水利工程 | 9篇 |
石油天然气 | 8篇 |
无线电 | 72篇 |
一般工业技术 | 142篇 |
冶金工业 | 914篇 |
原子能技术 | 24篇 |
自动化技术 | 131篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 49篇 |
2012年 | 17篇 |
2011年 | 47篇 |
2010年 | 46篇 |
2009年 | 34篇 |
2008年 | 25篇 |
2007年 | 35篇 |
2006年 | 22篇 |
2005年 | 22篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 21篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 54篇 |
1998年 | 281篇 |
1997年 | 154篇 |
1996年 | 103篇 |
1995年 | 55篇 |
1994年 | 55篇 |
1993年 | 60篇 |
1992年 | 12篇 |
1991年 | 27篇 |
1990年 | 21篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1977年 | 33篇 |
1976年 | 52篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1973年 | 6篇 |
排序方式: 共有1630条查询结果,搜索用时 31 毫秒
1.
2.
KG Basharin 《Canadian Metallurgical Quarterly》1997,(5):42-44
The study revealed the pathomorphology of pulmonary tuberculosis by using abundant retrospective materials from the prosectorship's archives (1061 autopsies), which referred to individuals who had died from pulmonary tuberculosis in the pretreatment and treatment periods. The comparative analysis of autopsies in the populational context is an important method of this new medical line of pathoanatomical investigations. 相似文献
3.
BACKGROUND: Laparoscopic Nissen fundoplication is an effective procedure for the treatment of gastro-oesophageal reflux disease (GORD), but the underlying motility mechanisms that explain the success of this operation remain unclear. METHODS: Twenty patients with a history of GORD underwent stationary oesophageal manometry and prolonged ambulatory pH monitoring, both before and 3 months after fundoplication. RESULTS: Eighteen patients were completely cured of reflux symptoms and stopped all antireflux medication after operation. After fundoplication there was a significant increase (P < 0.01) in median resting lower oesophageal sphincter (LOS) pressure and length. Median residual LOS pressure during swallow-induced LOS relaxation also increased significantly after operation (P < 0.01). The number of reflux episodes decreased from a median of 48 to 3 after fundoplication (P < 0.01). The time at pH less than 4 decreased from 5.7 to 0 per cent in the supine position (P < 0.01), and from 9.8 to 0.2 per cent while upright (P < 0.001). CONCLUSION: Early subjective results at 3 months following laparoscopic antireflux surgery show improved symptoms. One of the mechanisms underlying the antireflux action of fundoplication is an increase in median residual LOS pressure at the gastro-oesophageal junction. This may be a purely mechanical effect of the fundic wrap extrinsic to the LOS. 相似文献
4.
M Fornerod J van Deursen S van Baal A Reynolds D Davis KG Murti J Fransen G Grosveld 《Canadian Metallurgical Quarterly》1997,16(4):807-816
The oncogenic nucleoporin CAN/Nup214 is essential in vertebrate cells. Its depletion results in defective nuclear protein import, inhibition of messenger RNA export and cell cycle arrest. We recently found that CAN associates with proteins of 88 and 112 kDa, which we have now cloned and characterized. The 88 kDa protein is a novel nuclear pore complex (NPC) component, which we have named Nup88. Depletion of CAN from the NPC results in concomitant loss of Nup88, indicating that the localization of Nup88 to the NPC is dependent on CAN binding. The 112 kDa protein is the human homologue of yeast CRM1, a protein known to be required for maintenance of correct chromosome structure. This human CRM1 (hCRM1) localized to the NPC as well as to the nucleoplasm. Nuclear overexpression of the FG-repeat region of CAN, containing its hCRM1-interaction domain, resulted in depletion of hCRM1 from the NPC. In CAN-/- mouse embryos lacking CAN, hCRM1 remained in the nuclear envelope, suggesting that this protein can also bind to other repeat-containing nucleoporins. Lastly, hCRM1 shares a domain of significant homology with importin-beta, a cytoplasmic transport factor that interacts with nucleoporin repeat regions. We propose that hCRM1 is a soluble nuclear transport factor that interacts with the NPC. 相似文献
5.
Spores of Bacillus subtilis NCTC 8236 were treated with glutaraldehyde, Lugol's iodine, polyvinylpyrrolidone-iodine (PVP-I), sodium hypochlorite or sodium dichloroisocyanurate (NaDCC). After exposure survivors were enumerated on nutrient agar containing potential revival agents (subtilisin, lysozyme, calcium dipicolinate, calcium lactate). Of these, only calcium lactate had any significant enhancing effect and then only with iodine-treated spores. Calcium lactate (9 mmol l-1) in nutrient broth enhanced the rate and extent of germination of iodine-treated spores but not of spores previously subjected to glutaraldehyde, hypochlorite or NaDCC. 相似文献
6.
The pre- and postnatal findings of a fetus with a de novo del(13)(pter-->q21:) and an occipital encephalocoele are described. Maternal serum alpha-fetoprotein (AFP) screening at 19 weeks' gestation demonstrated a high level of 2.5 multiples of the median (MOM) and ultrasonography at 27 weeks' gestation showed severe intrauterine growth retardation, cardiomegaly, an occipital encephalocoele, and a calvarial defect. Genetic amniocentesis revealed a karyotype of 46,XX,del(13)(pter-->q21:). The proband postnatally displayed additional abnormalities such as microphthalmia, hypertelorism, large low-set ears, and micrognathia. We discuss the association of central nervous system (CNS) malformations with 13q deletions and emphasize that pregnancies with neural tube defects warrant cytogenetic analysis, especially when additional fetal abnormalities and neonatal dysmorphism are observed. 相似文献
7.
ED Schneiderman SM Willis CJ Kowalski TR Ten have 《Canadian Metallurgical Quarterly》1993,32(1):35-43
Sixty-five patients initially seropositive for IgM anti-phenolic glycolipid-I (PGL-I) antibodies were tested for antibody levels to PGL-I, lipoarabinomannan (LAM), and the 35-kDa protein of Mycobacterium leprae at regular intervals for up to 30 months following the commencement of multidrug therapy (MDT). There was a steady decline in IgM anti-PGL-I and anti-35-kDa antibody levels to a mean of 17% and 14%, respectively, of the starting level at 24 months. The development of type 1 and type 2 reactions or the presence of drug-resistant organisms in a small number of patients had no significant influence on the changes in antibody level. The rate of decline was similar in different disease categories, but a higher proportion of lepromatous patients remained seropositive at the end of 2 years of treatment than borderline tuberculoid patients. By contrast, the mean IgG anti-LAM antibody levels remained stable or increased. Again the occurrence of type 1 or type 2 reactions had no significant effect on antibody level over 2 years. Falls in the IgM anti-PGL-I antibody levels mirrored the falls in the bacterial index in individual patients and provide an additional parameter for monitoring the response to chemotherapy. 相似文献
8.
9.
10.
H. W. M. Ten Hoopen W. L. J. Hinrichs G. H. M. Engbers J. Feijen 《Journal of materials science. Materials in medicine》1996,7(11):699-704
The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated. Sterilization did not result in a release of heparin or heparin fragments from heparinized Cuprophan. Sterilization of heparinized Cuprophan by means of EtO exposure and gamma irradiation induced a slight, insignificant decrease of the anticoagulant activity. In contrast, steam-sterilized heparinized Cuprophan showed a higher anticoagulant activity than unsterilized heparinized Cuprophan, which was most likely caused by cleavage of some of the covalent bonds between heparin and Cupropha. The effects of sterilization on the permeability of unmodified Cuprophan and heparinized Cuprophan were compared. The permeability of unmodified Cuprophan for vitamin B12 (Vit B12) and sulfobromophthalein (SBP) was reduced by 20–35% after EtO exposure and gamma irradiation and was reduced by 90–95% after steam sterilization. The water permeability of unmodified Cuprophan remained the same after EtO exposure and gamma irradiation but also dramatically reduced after steam sterilization. These reductions were ascribed to the collapse of pores of the membrane. The permeability of heparinized Cuprophan was not affected by EtO exposure and gamma irradiation but dramatically reduced after steam sterilization, although to a lesser extent than in the case of unmodified Cuprophan. Apparently, the presence of immobilized heparin (partially) prevented the collapse of pores during sterilization. Gamma irradiation was recommended as the preferred method of sterilization for heparinized Cuprophan. 相似文献