全文获取类型
收费全文 | 1398篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 86篇 |
金属工艺 | 31篇 |
建筑科学 | 7篇 |
能源动力 | 11篇 |
轻工业 | 18篇 |
水利工程 | 1篇 |
无线电 | 17篇 |
一般工业技术 | 52篇 |
冶金工业 | 1135篇 |
原子能技术 | 3篇 |
自动化技术 | 45篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 22篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 17篇 |
2007年 | 15篇 |
2006年 | 12篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 36篇 |
1998年 | 374篇 |
1997年 | 221篇 |
1996年 | 152篇 |
1995年 | 72篇 |
1994年 | 50篇 |
1993年 | 71篇 |
1992年 | 14篇 |
1991年 | 6篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 13篇 |
1978年 | 1篇 |
1977年 | 30篇 |
1976年 | 70篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1411条查询结果,搜索用时 15 毫秒
1.
Pre-transplant nephrectomy was done in a 25-year-old man for calculous pyelonephritis using a retroperitoneal laparoscopic approach with a newly devised ligature applicator-dissector- kidney retractor. 相似文献
2.
M Hafezparast CG Cole GP Kaur RS Athwal PA Jeggo 《Canadian Metallurgical Quarterly》1994,20(6):541-548
A hamster-human hybrid containing only the q arm of chromosome 2 has been used to construct a panel of hybrids bearing reduced regions of chromosome 2 using the technique of irradiation fusion gene transfer. The human chromosome 2 carried the Ecogpt gene and all hybrids were selected using this marker. The integrated Ecogpt gene was localized to the region 2q33-34, resulting in the selective retention of this region in the hybrids. These data were combined with another previously constructed panel of hybrids containing regions of 2q, which were enriched for the region 2q36-37. The combined hybrid panel is useful for the mapping of new markers to defined regions of chromosome 2 and for the cloning of genes located on 2q by a positional strategy. 相似文献
3.
CG Willett 《Canadian Metallurgical Quarterly》1996,8(4):329-333
For the past 10 to 15 years, radiation therapy and chemotherapy have played an increasingly important role in the treatment of various gastrointestinal malignancies, most prominently in anal and rectal cancer. Critical issues in the care of patients with anal and rectal cancer include not only local control and survival but organ preservation as well. For patients with carcinoma of the anal canal, external-beam irradiation with 5-fluorouracil and chemotherapy with mitomycin C have replaced surgery as primary therapy. Current studies are optimizing this therapy. In contrast, the management of distal rectal cancer is in evolution. Although the abdominoperineal resection has been long regarded as the definitive treatment of distal rectal cancer, it is associated with substantial morbidity (loss of anorectal function with a permanent colostomy and a high incidence of sexual and genitourinary dysfunction). As an alternative, treatment programs utilizing sphincter-preserving procedures with radiation therapy and chemotherapy are under active investigation. In selected patients, these strategies appear promising, and there have been reports of satisfactory local control and survival, as well as preservation of sphincter integrity. 相似文献
4.
CG Enke 《Canadian Metallurgical Quarterly》1997,69(23):4885-4893
In electrospray ionization (ESI), droplets with a surface excess charge are created. The rate of production of surface excess charge is a constant and is equal to the rate of ion production. The ions appearing in the mass spectrum are postulated to be those that formed the surface excess charge at the time of droplet formation (or their collision products). An equilibrium model based on competition among the ions in the solution for the limited number of excess charge sites has been developed. This model accurately predicts the response curves of singly-charged ionic analytes as a function of the concentration of electrolyte and other analytes and provides an explanation for the selective effectiveness of ESI. At low concentrations of total analyte (micromolar and less), the response curves are linear, indifferent to the presence of other low concentration analytes, and suppressed by electrolyte concentrations in excess of the minimum required. At higher analyte concentrations, the response becomes independent of analyte concentration but highly affected by the presence of other analytes. 相似文献
5.
A Serrano Pascual C Merino Hernáez R Ochoa Mejías A Escolano Chamois J Golbano Ablanque I Otero Tejero M Sanz Redondo F Román Ruiz 《Canadian Metallurgical Quarterly》1997,21(6):631-635
BACKGROUND AND AIMS OF THE STUDY: Surgical treatment of functional tricuspid regurgitation associated with advanced valvular disease remains controversial, mainly due to the difficulty in choosing between valve replacement or reconstructive surgery. Failure to correct tricuspid regurgitation during valvular surgery carries a poor prognosis, as reoperation may represent a significant risk to the patient. Thus correct tricuspid valve surgery is vital to achieve improved early and long-term clinical results. METHODS: A total of 142 patients underwent concomitant tricuspid annuloplasty with mitral valve replacement and their clinical outcome was assessed. RESULTS: Overall hospital mortality rate was 11.3%. Seven patients died during follow up. The overall actuarial survival rate for 10 years was 74.1 +/- 14.2%. Postoperatively, 75.8% of the patients had no residual tricuspid insufficiency, while 24.2% had first- or second-degree tricuspid insufficiency and were treated medically. All patients were in NHYA functional class I or II postoperatively. CONCLUSION: Clinically, it is important to assess the severity of functional tricuspid insufficiency before and/or during the operation. Bicuspidalization annuloplasty for functional tricuspid insufficiency has provided good results, with a low incidence of reoperation and significant clinical improvement. The technique could be used in most patients with functional tricuspid regurgitation. 相似文献
6.
7.
The response of P. falciparum to chloroquine and pyrimethamine-sulfadoxine in vivo and chloroquine and amodiaquine in vitro was investigated in parasitaemic school children from six locations. Mean parasite sensitivity to chloroquine at day 7 was 74% (range 61-97) with parasite clearance rates between 2-3 days and complete defervescence in 85% of febrile children. Sensitivity declined in the four sites followed up to day 14 to 45% (range 37-53). Parasites were significantly more sensitive to pyrimethamine/sulfadoxine at 5/6 sites (100% day 7) but 5% of subjects became parasitaemic by day 14. In vitro isolates were significantly less sensitive to chloroquine than to amodiaquine with a mean 99% effective concentration of 348 mumol/L compared to 6.44 mumol/L. Clearly the role of chloroquine as the primary therapy for uncomplicated P. falciparum malaria should be reconsidered especially in the light of increasing disease severity and resurgence. Amodiaquine may be suitable alternative with pyrimethamine/sulfadoxine as second line and for more severe malaria prior to referral. The cost of alternative antimalarials and the dynamic and deteriorating pattern of resistance are powerful arguments for more objective slide diagnosis to minimise drug pressure and a regular drug sensitivity surveillance system. We believe that the latter should concentrate on measuring clinical drug efficacy in symptomatic outpatients rather than in asymptomatic children while the former needs more pragmatic and economical strategies possibly centred on seasonality and risk. 相似文献
8.
Summary The potential of the micro-Fourier Transform Raman tool in examining specific localized regions in polymeric materials with some degree of fluorescence when analyzed by conventional Raman spectroscopy is examined. Analysis of characteristic bands of the vibrational spectra obtained in a small area damaged by a visible and NIR laser beam in commercial Polyethylene Terephthalate (PET) shows a different conformer ratio than that observed in a non irradiated zone. 相似文献
9.
A. Ureña J. M. Gomez De Salazar J. Quiñones S. Merino J. Martin 《Journal of Materials Science》1996,31(3):807-817
Diffusion bonds have been produced between sheets of an Al-Li-Cu-Mg-Zr alloy using aluminium-4% copper vapour deposited metallic interlayers. Microstructural changes occurred both in the parent alloy and in the bond interface after diffusion bonding cycles and post-bonding heat treatments were analysed. Different metallographic techniques (light microscopy, scanning and transmission electron microscopy) have been used. Diffusion bonding trials were carried out using the same alloy (AA8090), both in non-superplastic (T6) and superplastic conditions. Differences in their behaviours in relation to diffusion bonding were observed. 相似文献
10.