全文获取类型
收费全文 | 719篇 |
免费 | 41篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 4篇 |
综合类 | 11篇 |
化学工业 | 8篇 |
金属工艺 | 6篇 |
机械仪表 | 12篇 |
建筑科学 | 9篇 |
矿业工程 | 5篇 |
轻工业 | 11篇 |
水利工程 | 39篇 |
石油天然气 | 1篇 |
无线电 | 69篇 |
一般工业技术 | 14篇 |
冶金工业 | 492篇 |
原子能技术 | 4篇 |
自动化技术 | 80篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 15篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 20篇 |
2005年 | 49篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 27篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 12篇 |
1998年 | 139篇 |
1997年 | 77篇 |
1996年 | 60篇 |
1995年 | 29篇 |
1994年 | 35篇 |
1993年 | 15篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1978年 | 1篇 |
1977年 | 27篇 |
1976年 | 44篇 |
1975年 | 2篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有765条查询结果,搜索用时 178 毫秒
101.
102.
KL Weir EN O''Gorman JA Ross DJ Godden AD McKinnon PW Johnston 《Canadian Metallurgical Quarterly》1994,150(3):784-789
Uterine leiomyomas or fibroids are common among women of reproductive age, but their biology is poorly understood. The PTH-related protein (PTHrP) has been identified in a number of sites throughout the reproductive tract. We, therefore, examined whether fibroids express PTHrP mRNA and compared their level of expression with that in normal myometrium. Total RNA prepared from fibroid tissue and corresponding normal myometrium from seven patients was examined by RNase protection analysis. In all cases, fibroid and myometrial tissue expressed PTHrP, and in six of seven cases, PTHrP expression was higher in fibroids than in normal myometrium. Cultured fibroid cells from four patients also expressed higher levels of PTHrP mRNA than corresponding cultured normal myometrial cells. Tissue extracts from eight patients and conditioned medium from cultured cells from nine patients were examined for PTHrP immunoreactivity using a two-site immunoradiometric assay. In tissue extracts and conditioned medium, the mean PTHrP concentration was significantly higher in fibroids than normal myometrium. Immunohistochemical staining of fibroid and myometrial tissue was positive for PTHrP. Finally, PTHrP-(1-34) induced a dose-dependent increase in cAMP in fibroid and myometrial cells in vitro. These findings suggest that PTHrP may have an autocrine/paracrine function in regulating myometrial physiology and may play a role in regulating fibroid growth or differentiation. 相似文献
103.
104.
SJ Milstein EN Barantsevitch VA Grechanovski DJ Sarubbi 《Canadian Metallurgical Quarterly》1996,13(6):651-665
Soybean hydrolysate is a hydrophilic mixture of amino acids and low molecular peptides which are soluble over the whole pH range. Chemical modification of soybean hydrolysate with aromatic acyl chlorides resulted in a product that yielded pH-dependent microspheres. Investigation into the physiochemical properties of the microsphere forming material indicated that acylation had alerted the hydrophobic/hydrophilic ratio as evidenced by an increased column retention time on reverse phase HPLC. This was further confirmed by analysis of the amino acid composition of the modified material. The data indicated that the hydrophobic/hydrophilic ratio and low molecular were critical factors in the formation of this supramolecular complex. An estimation based on sedimentation rate revealed an average molecular weight of these microspheres as 10(7)-10(8) Daltons. Light scattering experiments indicated that the microspheres have discrete chambers in the interior. Included among the properties of the microspheres that have been determined are the pH range of the phase transition, size distribution and zeta-potential. The physiochemical characteristics of the microspheres prepared from modified soybean protein are similar to the microsphere forming material produced by thermal condensation of amino acids. Formation of microspheres in solution containing either porcine insulin or salmon calcitonin resulted in the encapsulation of nearly 60% of the dissolved proteins. Oral gavage of encapsulated porcine insulin or salmon calcitonin into the stomach of rats resulted in significant titers of either protein in the systematic circulation. 相似文献
105.
106.
Skeletal fixation can be very beneficial to the recovery of wrist and hand function after a displaced fracture because it allows mobilization of soft tissues before the completion of fracture healing. The benefits of skeletal fixation can be greatly diminished, however, if excessive force causes the fixation to fail before fracture healing has occurred, infection occurs around the implant, or the patient develops reflex sympathetic dystrophy. Those complications, as well as others, are often caused by inappropriate or inadequate hand therapy. This article discusses the techniques needed to avoid many such complications while providing the best possible functional result for every patient. 相似文献
107.
108.
109.
EN Vasil''eva 《Canadian Metallurgical Quarterly》1976,96(1):6-11
The influence exerted by the quality of alimentary protein on the composition of the secreted bile, morphology of the liver and gallbladder, as well as on the formation of gallstones was studied in experiments with rats and hamsters. It is shown that with inclusion in an experimental fat-free ration of qualitatively incomplete protein gelatin (instead of caseine) the frequency of the gallstones formation increases by almost 6 times. In animals this is attended by a reduced concentration of a number of major bile components. Upon feeding for 2 weeks on lithogenic ration with gelatin morphological investigations disclose inflammatory changes in the gallbladder wall, and after a lapse of 3 weeks--multiple exulcerations in the mucosa and a dense gross sediment in the gallbladder lumen. 相似文献
110.
EN Pugh 《Canadian Metallurgical Quarterly》1976,257(3):713-747
The ppi1 colour mechanism was isolated by means of Stile's auxiliary field technique: that it is pi1 which is isolated is proven by both test and field action spectra. 2. The fundamental mechanisms of human trichromatic colour vision must satisfy Grassman's law of additivity. The hypothesis that pi1 is one of the three fundamentals is tested by experiments in which pairs (u1, u2) of monochromatic adapting fields are mixed 3. When two fields with wave-lengths in the neighbourhood of its primary mode (mu1, mu2 less than or equal to 500 nm) are combined, pi1 is field-additive, consistent with the hypothesis that this portion of the pi1 action spectrum is that of the short-wave-length-sensitive photoreceptors. 4. When a short-wave-length adaptation field (mu1 less than or equal to 500 nm) is mixed with a longer wave-length field (mu2 greater than or equal 550 nm) i1 is strongly non-additive. This result proves that the long-wave-length portion of the pi1 field spectrum is generated at least in part by a signal originating in the long- or middle-wave-length sensitive cones. 5. Analysis of the additivity failures supports a model of pi1 in which the signal to be detected is generated in the short-wave-length cones, and must pass serially through two gain stages: the gain in the first stage is controlled by the short-wave-length cones alone; the gain in the second stage is controlled by a signal originating in the middle, or long-wave-length cones, or both. 相似文献