全文获取类型
收费全文 | 2556篇 |
免费 | 48篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 207篇 |
金属工艺 | 17篇 |
机械仪表 | 17篇 |
建筑科学 | 67篇 |
矿业工程 | 1篇 |
能源动力 | 27篇 |
轻工业 | 118篇 |
水利工程 | 6篇 |
石油天然气 | 7篇 |
无线电 | 113篇 |
一般工业技术 | 268篇 |
冶金工业 | 1626篇 |
原子能技术 | 8篇 |
自动化技术 | 116篇 |
出版年
2021年 | 10篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 20篇 |
2015年 | 22篇 |
2014年 | 21篇 |
2013年 | 79篇 |
2012年 | 24篇 |
2011年 | 34篇 |
2010年 | 24篇 |
2009年 | 24篇 |
2008年 | 54篇 |
2007年 | 35篇 |
2006年 | 35篇 |
2005年 | 30篇 |
2004年 | 34篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 68篇 |
1998年 | 482篇 |
1997年 | 294篇 |
1996年 | 192篇 |
1995年 | 110篇 |
1994年 | 78篇 |
1993年 | 117篇 |
1992年 | 33篇 |
1991年 | 47篇 |
1990年 | 43篇 |
1989年 | 46篇 |
1988年 | 31篇 |
1987年 | 25篇 |
1986年 | 27篇 |
1985年 | 36篇 |
1984年 | 21篇 |
1983年 | 18篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 28篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1977年 | 42篇 |
1976年 | 71篇 |
1975年 | 18篇 |
1974年 | 11篇 |
1973年 | 12篇 |
1966年 | 12篇 |
排序方式: 共有2605条查询结果,搜索用时 31 毫秒
1.
2.
3.
The purpose of this study was to identify the optimal knot construction for interrupted dermal sutures. A synthetic braided absorbable suture, sizes 3-0 and 5-0, was selected for this evaluation. With reproducible mechanical performance tests, we determined that the construction of secure knots without ears required one additional throw as compared with secure knots with 3-mm ears. The direction of applied tension did not alter knot security, with the exception of granny knots, which required an extra throw when tension was applied parallel to the suture loop. Because interrupted dermal knot construction is accomplished without knot ears and with an applied tension parallel to the wound, one additional throw must be added to the knot to ensure knot security. 相似文献
4.
5.
A Abeliovich C Chen Y Goda AJ Silva CF Stevens S Tonegawa 《Canadian Metallurgical Quarterly》1993,75(7):1253-1262
Calcium-phospholipid-dependent protein kinase (PKC) has long been suggested to play an important role in modulating synaptic efficacy. We have created a strain of mice that lacks the gamma subtype of PKC to evaluate the significance of this brain-specific PKC isozyme in synaptic plasticity. Mutant mice are viable, develop normally, and have synaptic transmission that is indistinguishable from wild-type mice. Long-term potentiation (LTP), however, is greatly diminished in mutant animals, while two other forms of synaptic plasticity, long-term depression and paired-pulse facilitation, are normal. Surprisingly, when tetanus to evoke LTP was preceded by a low frequency stimulation, mutant animals displayed apparently normal LTP. We propose that PKC gamma is not part of the molecular machinery that produces LTP but is a key regulatory component. 相似文献
6.
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
7.
J Stevens 《Canadian Metallurgical Quarterly》1998,40(7):469-471
OBJECTIVE: To determine the actual use of 'statin' therapy for primary and secondary prevention and the potential effect of using the Sheffield Table for primary prevention of coronary heart disease upon 'statin' use in a consultant-run Hypertension and Cardiovascular Risk Clinic. DESIGN: Prospective audit of the current use of cholesterol-lowering therapy and the effect of implementing the criteria used in the Sheffield Table and the Scandinavian Simvastatin Study for cholesterol lowering in 'at risk' patients upon statin use in a consultant-led cardiovascular risk clinic. SETTING: The Aberdeen Hypertension Clinic. RESULTS: A total of 1500 patients were reviewed of which 416 (27.7%) had experienced at least one clinical manifestation of atherosclerotic cardiovascular disease (CVD) and 392 (94%) of these had a total cholesterol measured of whom 298 (76%) had a total cholesterol >5.5 mmol/l. Only 11.2% of eligible patients were actually receiving lipid-lowering treatment for secondary prevention. A total of 1084 patients with no prior cardiovascular disease were identified, 97 (8.9%) were excluded because of age. Using the Sheffield Table, 92 (9.4%) of these patients were eligible for statin therapy and only six of the 92 patients were actually receiving treatment. CONCLUSIONS: The results of this study reveal that even in a consultant-led cardiovascular prevention clinic there is a significant discrepancy between optimal evidence-based management and the actual delivery of clinical care. Seventy-two per cent and 9.3% of patients attending the clinic were eligible for statin treatment for secondary and primary prevention, respectively. However, only 11.2% of patients suitable for secondary prevention and 6.5% of patients suitable for primary prevention were actually receiving appropriate lipid-lowering therapy. Considering the proven benefit of this form of medical intervention the results of this study are of real importance to practising clinicians and patients alike. 相似文献
8.
9.
Scientific co-operation in Europe and the citation of multinationally authored papers 总被引:3,自引:1,他引:2
Under the sponsorship of the U.S. National Science Foundation, CHI Research, Inc. developed the bibliometric indicators for the U.S. National Science Board'sScience Indicators Reports starting withScience Indicators 1972. In the work reported here, for the Commission of the European Communities, CHI has extended the Science Indicators techniques and database to a study of publication, coauthorship and citation within 28 scientific fields related to various European Community programs.Perhaps the most important finding of the research was that internationally coauthored papers — papers authored by scientists affiliated with institutions in more than one EC country — were cited two times as highly as papers authored by scientists working at a single institution within a single country. These EC-EC internationally coauthored papers were cited as highly as EC-Non EC and Non-EC papers. This indicates that the internationally linked European science is of as high impact as any other science in the world.A second key finding was that, after compensating for national scientific size, the degree of international coauthorship did not appear to be particularly dependent upon size. However, linguistic and cultural factors were found to be very strong. The patterns of coauthorship amongst the European countries are far from homogeneous, and are quite heavily affected by linguistic, historical, and cultural factors.Finally, it was found that international coauthorship is increasing steadily, both within and outside of the Community, with some evidence that international cooperation is increasing more rapidly in scientific fields that have been targeted by the Commission.This work has been sponsored by the MONITOR programme of the Commission of the European Communities. 相似文献
10.
Stevens M. Williams P.D. Peterson G.L. Kurkowski S.H. 《Computational Intelligence Magazine, IEEE》2008,3(2):65-68
This research supports the hypothesis that the Trust Vector model can be modified to fit the CyberCraft Initiative, and that there are limits to the utility of historical data. This research proposed some modifications and expansions to the Trust Model Vector, and identified areas for future research. 相似文献