全文获取类型
收费全文 | 1701篇 |
免费 | 10篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 64篇 |
金属工艺 | 2篇 |
机械仪表 | 7篇 |
建筑科学 | 14篇 |
矿业工程 | 3篇 |
能源动力 | 9篇 |
轻工业 | 49篇 |
水利工程 | 7篇 |
无线电 | 46篇 |
一般工业技术 | 52篇 |
冶金工业 | 1393篇 |
原子能技术 | 3篇 |
自动化技术 | 54篇 |
出版年
2022年 | 4篇 |
2021年 | 6篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 38篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 45篇 |
1998年 | 375篇 |
1997年 | 211篇 |
1996年 | 151篇 |
1995年 | 90篇 |
1994年 | 88篇 |
1993年 | 84篇 |
1992年 | 29篇 |
1991年 | 37篇 |
1990年 | 25篇 |
1989年 | 30篇 |
1988年 | 26篇 |
1987年 | 27篇 |
1986年 | 21篇 |
1985年 | 29篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 34篇 |
1976年 | 95篇 |
1975年 | 10篇 |
1971年 | 5篇 |
1967年 | 2篇 |
1958年 | 2篇 |
1906年 | 2篇 |
排序方式: 共有1711条查询结果,搜索用时 0 毫秒
991.
Seventeen children with diaphyseal both-bone forearm fractures, for which closed reduction had failed, were treated with fixation of either the radius or ulna. Sixteen were followed up to their clinical end point. Results in all children were excellent; all had a full return of motion except two who lacked 5 degrees of pronation. This retrospective series is the first reported to date looking exclusively at diaphyseal both-bone forearm fractures in children treated with fixation of a single bone. The rationale of treatment is to stabilize one bone while the other is rotated into reduction. Repeated anesthetics are avoided, and malreduction is prevented without adult-style both-bone plating. We prefer intramedullary fixation as hardware is easier and safer to place and remove. 相似文献
992.
DO Clegg DJ Reda MH Weisman JJ Cush FB Vasey HR Schumacher E Budiman-Mak DJ Balestra WD Blackburn GW Cannon RD Inman FP Alepa E Mejias MR Cohen R Makkena ML Mahowald J Higashida SL Silverman N Parhami J Buxbaum CM Haakenson RH Ward BJ Manaster RJ Anderson WG Henderson 《Canadian Metallurgical Quarterly》1996,39(12):2021-2027
OBJECTIVE: To determine whether sulfasalazine (SSZ) at a dosage of 2,000 mg/day is effective in the treatment of reactive arthritis (ReA) that has been unresponsive to nonsteroidal antiinflammatory drug (NSAID) therapy. METHODS: One hundred thirty-four patients with ReA who had failed to respond to NSAIDs were recruited from 19 clinics, randomized (double-blind) to receive either SSZ or placebo, and followed up for 36 weeks. The definition of treatment response was based on joint pain/tenderness and swelling scores and physician and patient global assessments. RESULTS: Longitudinal analysis revealed improvement in the patients taking SSZ compared with those taking placebo, which appeared at 4 weeks and continued through the trial (P = 0.02). At the end of treatment, response rates were 62.3% for SSZ treatment compared with 47.7% for placebo treatment. The Westergren erythrocyte sedimentation rate declined more with SSZ treatment than with placebo (P < 0.0001). Adverse reactions were fewer than expected and were mainly due to nonspecific gastrointestinal complaints. CONCLUSION: SSZ at a dosage of 2,000 mg/day is well tolerated and effective in patients with chronically active ReA. 相似文献
993.
994.
A procedure for production of monoclonal antibodies to testosterone is described. The method involves immunization of rats with a bovine serum albumin conjugate of testosterone 3-(0-carboxymethyl) oxime followed by polyethylene glycol induced hybridization of the immune lymphocytes with mouse myeloma cells. The resulting hybridomas were cloned and the antibodies produced by each clone were characterized. All the antibodies obtained showed high affinity for testosterone, (Ka = 10(10) 1/mol), but clones differed widely in the degree of cross-reaction of the antibodies with other steroids, such as 5 alpha-dihydrotestosterone (range 2-100%) and androstenedione (less than 0.1-4%). Large quantities of the selected specific antibodies can be obtained by mass growth of the hybridoma line in culture or as tumors in irradiated or nude mice. Monoclonal antibody preparations may improve standardization of immunoassay methods. 相似文献
995.
To investigate the roles of angiotensin II and sodium in essential high-renin, normal-renin and low-renin hypertension, 14 patients received the competitive antagonist of angiotensin II, saralasin, during periods of sodium depletion and repletion. Blood-pressure response to saralasin was determined by the state of sodium balance. Patients from all three renin subgroups exhibited a fall in blood pressure when sufficiently sodium depleted, and an elevation in blood pressure when sodium replete or insufficiently depleted. However, those with low renin required loss of substantially more sodium (sufficient to elicit compensatory stimulation of renin) before depletion could be achieved. In patients with essential hypertension of all three renin subgroups, sodium balance determines the degree of participation of the renin-angiotensin system in sustaining high blood pressure. Even the low-renin type can become renin dependent with sufficient sodium depletion. 相似文献
996.
E Lewis ME Bernardino PA Barnes HR Parvey CS Soo VP Chuang 《Canadian Metallurgical Quarterly》1983,7(2):235-241
Five patients with known primary malignancy demonstrated fatty infiltration of the liver on routine computed tomography (CT) examination. Within the diffuse fatty infiltration were focal areas of relatively increased beam attenuation in four cases. These areas of increased beam attenuation are nonspecific as to etiology. Their differential diagnosis is discussed. Since the true extent of the neoplastic process may be underestimated by conventional CT and celiac angiography, superselective angiography, computed angiotomography, or biopsy is required to accurately assess the etiology and the extent of the disease. 相似文献
997.
The addition of furosemide to the fluid used to perfuse isolated rat kidney increases the kallikrein activity found in the perfusion fluid. The experiments favour the concept that furosemide activates a kallikrein precursor or/and the synthesis and release of kallikrein in the kidneys. 相似文献
998.
W. G. Waters II 《The Annals of Regional Science》1976,10(1):98-103
Studies which estimate the economic and socialimpacts of a public project can be confused with studies whichevaluate the economic and social merit of a project relative to alternatives. This paper contrasts the different purposes and orientation of these two types of studies and outlines their respective roles in the planning and evaluation of public projects.The author wishes to thank Harry F. Campbell, H. Craig Davis and Trevor D. Heaver for helpful comments and conversations. The author, of course, bears full responsibility for the finished project. 相似文献
999.
1000.
1. Unreduced human subcomponent C1q was shown by electrophoresis on polyacrylamide gels run in the presence of sodium dodecyl sulphate to be composed of two types of non-covalently linked subunits of apparent mol.wts. 69 000 and 54 000. The ratio of the two subunits was markedly affected by the ionic strength of the applied sample. At a low ionic strength of applied sample, which gave the optimum value for the 54 000-apparent mol.wt. subunit, a ratio of 1.99:1.00 was obtained for the ratio of the 69 000-apparent mol.wt. subunit to the 5400-apparent-mol.wt. subunit. The amount of the 54 000-apparent-mol.wt. subunit detected in the expected position on the gel was found to be inversely proportional to increases in the ionic strength of the applled sample. 2. Human subcomponent C1q on reduction and alkylation, or oxidation, yields equimolar amounts of three chains designated A, B and C [Reid et al. (1972) Biochem. J. 130, 749-763]. The results obtained by Yonemasu & Stroud [(1972) Immunochemistry 9, 545-554], which showed that the 69 000-apparent-mol.wt. subunit was a disulphide-linked dimer of the A and B chains and that the 54 000-apparent-mol.wt. subunit was a disulphide-linked dimer of the C chain, were confirmed. 3. Gel filtration on Sephadex G-200 in 6.0M-guanidinium chloride showed that both types of unreduced subunit were eluted together as a single symmetrical peak of apparent mol.wt. 49 000-50 000 when globular proteins were used as markers. The molecular weights of the oxidized or reduced A, B and C chains have been shown previously to be very similar all being in the range 23 000-24 000 [Reid et al. (1972) Biochem. J. 130, 749-763; Reid (1974) Biochem. J. 141, 189-203]. 4. It is proposed that subcomponent C1q (mol.wt. 410000) is composed of nine non-covalently linked subunits, i.e. six A-B dimers and three C-C dimers. 5. A structure for subcomponent C1q is proposed and is based on the assumption that the collagen-like regions of 78 residues in each of the A, B and C chains are combined to form a triple-helical structure of the same type as is found in collagens. 相似文献