全文获取类型
收费全文 | 1894篇 |
免费 | 11篇 |
专业分类
电工技术 | 7篇 |
综合类 | 2篇 |
化学工业 | 124篇 |
金属工艺 | 4篇 |
机械仪表 | 5篇 |
建筑科学 | 23篇 |
能源动力 | 2篇 |
轻工业 | 33篇 |
水利工程 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 35篇 |
冶金工业 | 1626篇 |
原子能技术 | 5篇 |
自动化技术 | 13篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2017年 | 3篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 22篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 12篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 12篇 |
1999年 | 54篇 |
1998年 | 472篇 |
1997年 | 259篇 |
1996年 | 189篇 |
1995年 | 121篇 |
1994年 | 84篇 |
1993年 | 94篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 29篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 8篇 |
1978年 | 17篇 |
1977年 | 53篇 |
1976年 | 97篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1926年 | 2篇 |
1890年 | 4篇 |
1882年 | 2篇 |
排序方式: 共有1905条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
KH Naifeh PH Heller F Perry NC Gordon JD Levine 《Canadian Metallurgical Quarterly》1983,16(3):277-283
We used certain physiologic maneuvers to perturb the autonomic nervous system (ANS) in an attempt to detect a link between the ANS and pain. In the unperturbed state, we found no difference in the electrodermal response among normal controls, preoperative patients (increased stress without pain) and postoperative patients (increased stress and pain). The electrodermal response elicited by autonomic maneuvers was significantly attenuated in postoperative patients but not in preoperative patients or in normal control subjects. 相似文献
95.
The theory of urethral resistance and the derivation or mural tension have been discussed. A method for the continuous calculation and presentation of these parameters has been described. Urethral resistance and mural tensions are altered by the presence of bladder outflow obstruction and have been shown to return to normality after the obstruction is removed. 相似文献
96.
Infrared reflectance spectra of oxide films on hot rolled 3004 and 5182 aluminum alloy surfaces indicate the presence of two types of magnesium-doped aluminum oxide. Heating the samples to 350°C or more causes shifting and broadening of the 900 cm?1 aluminum-oxygen absorption band for 3004 metal, and the appearance of a magnesium-oxygen absorption band at 670 cm?1 in the reflectance spectra of both 3004 and 5182 metal.Reflectance spectra of the surfaces on cold rolled 3004 and 5182 metal show no absorption bands on unheated samples. However, results from time-temperature studies indicate that further oxidation of these samples is more rapid than in hot rolled samples. The oxides formed on cold and hot rolled 5182 metal are similar, while cold rolled 3004 metal initially forms an oxide which differs from that on hot rolled 3004 metal, exhibiting a broader absorption band at approximately 850 cm?1. 相似文献
97.
PH Weil 《Canadian Metallurgical Quarterly》1982,94(7):176-177
We reviewed 395 patients with isolated hemo- or hemopneumothorax from stab or bullet wounds. Of these, 45 were in shock on admission. All patients were initially treated by closed thoracostomy and infusions or transfusions. Of the 45 patients in shock, 24 responded to this treatment and remained stable. The other 21, after an initial response, showed a renewed drop in blood pressure and rise in pulse rate and had to be explored. All were found to be bleeding from either a systemic artery or a major lung laceration extending into the hilus. All other patients were continued on tube drainage, supplemented, if necessary, by needle aspiration and instillation of fibrinolytic enzymes until the lung was fully expanded, thus avoiding empyemas and the need for decortications. We found the clinical course after initial tube thoracostomy to be a reliable indicator for thoracotomy or for continued non-operative management, thus avoiding unnecessary thoracotomies. 相似文献
98.
99.
M Paulli E Berti E Boveri S Kindl E Bonoldi C Gambini R Rosso G Borroni V Straccapansa U Magrini JE DeCoteau PH Krammer P M?ller ME Kadin 《Canadian Metallurgical Quarterly》1998,29(11):1223-1230
The spectrum of CD30+ cutaneous lymphoproliferative disorders is characterized by the histology of a high-grade lymphoma but frequent clinical regression of skin lesions in lymphomatoid papulosis (LyP) and occasional regression in CD30+ large cell lymphomas (LCLs). A recent study shows that apoptosis may be a significant mechanism of regression of LyP (Arch Dermatol 133:828-833, 1997). Therefore, we studied expression of proteins that induce apoptosis, including CD27, CD40, CD95, and nerve growth factor receptor (NGF-R), as well as anti-apoptotic protein bcl-2 in skin lesions from 25 patients within the spectrum of CD30+ cutaneous lymphoma. Our results show consistent expression of CD95 (APO-1/Fas), but rare or absent expression of CD27, CD40, and NGF-R on tumor cells from both regressing LyP lesions and nonregressing CD30+ lymphomas. Bcl-2 was expressed at low levels in LyP and at high levels in pleomorphic CD30+ lymphomas. These results indicate that, in addition to CD30, CD95 expression is preferentially expressed at high levels in all cutaneous CD30+ lymphomas and suggest that CD95 may play a role in the regression of CD30+ skin lesions. Expression of bcl-2 appears to protect tumor cells from apoptosis in CD30+ lymphoproliferative disorders. 相似文献
100.
S Corvaisier PH Maire MY Bouvier d'Yvoire X Barbaut N Bleyzac RW Jelliffe 《Canadian Metallurgical Quarterly》1998,42(7):1731-1737
Various suggestions have been made for empirical pharmacodynamic indices of antibiotic effectiveness, such as areas under the drug concentration-time curve in serum (AUC), AUC > MIC, AUC/MIC, area under the inhibitory curve (AUIC), AUC above MIC, and time above MIC (T > MIC). In addition, bacterial growth and killing models, such as the Zhi model, have been developed. The goal of the present study was to compare the empirical behavior of the Zhi model of bacterial growth and killing with the other empirical pharmacodynamic indices described above by using simulated clinical data analyzed with the USC*PACK PC clinical programs for adaptive control of drug therapy, with one model describing a concentration-dependent antibiotic (tobramycin) and another describing a concentration-independent antibiotic (ticarcillin). The computed relative number of CFU was plotted against each pharmacodynamic index, with each axis parameterized over time. We assumed that a good pharmacodynamic index should present a clear and continuous relationship between the time course of its values and the time course of the bacterial killing as seen with the Zhi model. Preliminary work showed that some pharmacodynamic indices were very similar. A good sensitivity to the change in the values of the MIC was shown for AUC/MIC and also for T > MIC. In addition, the time courses of some other pharmacodynamic indices were very similar. Since AUC/MIC is easily calculated and shows more sensitivity, it appeared to be the best of the indices mentioned above for the concentration-dependent drug, because it incorporated and used the MIC the best. T > MIC appeared to be the best index for a concentration-independent drug. We also propose a new composite index, weighted AUC (WAUC), which appears to be useful for both concentration-dependent and concentration-independent drugs. 相似文献