全文获取类型
收费全文 | 1001篇 |
免费 | 0篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 30篇 |
金属工艺 | 3篇 |
机械仪表 | 13篇 |
矿业工程 | 3篇 |
能源动力 | 2篇 |
轻工业 | 1篇 |
石油天然气 | 2篇 |
无线电 | 66篇 |
一般工业技术 | 76篇 |
冶金工业 | 795篇 |
原子能技术 | 3篇 |
自动化技术 | 6篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 13篇 |
2011年 | 19篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 11篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 31篇 |
1998年 | 237篇 |
1997年 | 123篇 |
1996年 | 93篇 |
1995年 | 51篇 |
1994年 | 42篇 |
1993年 | 54篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 28篇 |
1976年 | 72篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有1001条查询结果,搜索用时 15 毫秒
1.
EB Guglia 《Canadian Metallurgical Quarterly》1996,(10):34-36
The authors elaborated a method measuring air level of orthophosphorous and orthophosphoric acids by means of ion chromatography within the range of 0.1-25 mg/cu m. The samples are extracted through concentration on a filter. The analysis regime includes depression of the background levels. The separating column (4 x 200 mm) is filled with anion exchanger BT IAN, the suppressing column (6 x 150 mm) is filled with cation exchanger Dowex 50 x 8, the elutriating agent is 1.5 mM of sodium carbonate, the detector is conductometric. Minimal amounts of ions that could be detected in the analyzed solution are 7-10 ng (HPO32-), 10-15 ng (HPO 42-). The method is designed to analyze the air of workplace. 相似文献
2.
OBJECTIVE: To describe an immunocompromised patient (without AIDS) with nosocomial infectious diarrhea caused by Pseudomonas aeruginosa. Oral ciprofloxacin therapy proved to be effective. CASE SUMMARY: An 80-year-old woman with type II diabetes mellitus and hypertension developed progressive renal insufficiency, was hospitalized because of uremia, and underwent hemodialysis. When the patient developed hematochezia, Duke's C sigmoid colon cancer was detected and successfully resected. She received broad-spectrum antibiotics in the perioperative period. The patient then developed profuse diarrhea associated with abdominal cramping, a low-grade fever, prostration, and headache. The patient then started to received vancomycin 500 mg po qid empirically. Four days later, the diarrhea continued unabated, the Clostridium difficile titer was negative, and the vancomycin therapy was stopped. However, the stool culture was positive for heavy growth of P. aeruginosa sensitive to ciprofloxacin. The patient then began to receive ciprofloxacin 500 mg po bid. Within 3 days the diarrhea stopped. Oral ciprofloxacin therapy was continued for 10 days and the patient remained free of symptoms with formed stools thereafter. DISCUSSION: Diarrhea following the use of broad-spectrum antibiotics implicates pseudomembranous colitis as the cause. The patient did not respond to oral vancomycin therapy and had a negative stool assay for C. difficile toxin. This patient was believed to have Pseudomonas enteritis, which was confirmed by 2 positive stool cultures. The administration of oral ciprofloxacin therapy stopped her diarrhea with a rapid resolution of symptoms. CONCLUSIONS: P. aeruginosa as a cause of infectious diarrhea is unusual. When it occurs, it usually represents a nosocomial infection in an immunocompromised host. This report illustrates that oral ciprofloxacin therapy is effective for Pseudomonas enteritis, with rapid resolution of symptoms. 相似文献
3.
4.
C Gnardellis A Trichopoulou K Katsouyanni E Polychronopoulos EB Rimm D Trichopoulos 《Canadian Metallurgical Quarterly》1995,6(1):74-77
The involvement of mental health professionals in determinations of dangerousness is both common and controversial. Among the various contexts for these evaluations, the release of potentially violent forensic patients from maximum security facilities evokes justified concern from involved experts and apprehension to outrage from the immediate community. We sought to examine how conclusions are reached on dangerousness at two sequential stages: clinical recommendations and Manifest Dangerousness Hearings decisions. In an archival study of 245 patients, we found that lack of progress in the institution and physical assaultiveness were the strongest correlates with dangerousness. In contrast, experts and review boards appeared to be relatively less influenced by diagnosis, types of treatment, and sociodemographic variables. 相似文献
5.
Fifteen fresh cadaver impacts were conducted in simulation of pedestrian-automobile accidents. The test sled configuration simulated an automobile bumper and hood in "standard" and "nosedive" situations as well as "hard" and "soft" impact surfaces. Instrumentation and film demonstrated large axial compression forces in the struck leg and considerable angular velocity of the torso in all modes. Dissection revealed primary injury at the impact site at low velocities with added remote injury at high velocities. Fracture of the lateral tibial plateau was most common. Lowering the bumper height offered the greatest protection against injury at moderate impact velocities. 相似文献
6.
V. A. Volodin E. I. Gatskevich A. V. Dvurechenskii M. D. Efremov G. D. Ivlev A. I. Nikiforov D. A. Orekhov A. I. Yakimov 《Semiconductors》2003,37(11):1315-1320
The effect of pulsed ruby laser radiation on Ge nanoclusters grown on a (100)-oriented Si substrate is studied. The energy density of radiation corresponds to the melting threshold of the Si surface. Changes in the structure of nanoclusters are analyzed by comparing the experimental Raman spectra to those calculated in terms of Born-von Karman and Vol’kenstein models. It is established that the action of one pulse changes the cluster size and partly relieves the compression. Still greater changes take place in a sample subjected to ten pulses. The Ge nanoclusters transform into clusters of GexSi1?x solid solution, presumably due to the stress-and vacancy-aided diffusion. Laser-induced thermal processes in germanium nanoclusters in silicon are numerically simulated. 相似文献
7.
A. N. Gruzintsev G. A. Emelchenko A. N. Redkin W. T. Volkov E. E. Yakimov G. Visimberga 《Semiconductors》2010,44(9):1235-1240
The effect of the length of ZnO nanorods (500 nm in diameter) on the mode structure of their lasing in the ultraviolet spectral
region is studied by optical luminescence microscopy. It is shown that separate nanorods with a metal mirror at one of the
end faces exhibit only two or three laser modes at small nanoresonator lengths (8–20 μm). The different optical losses of
longitudinal and transverse waveguide modes are established for nanorods lying on a glass substrate. An increase in the optical
Q factor and a decrease in the lasing thresholds can be attributed to optical reflection from the metal mirror at the end
face of the nanorod. 相似文献
8.
A. N. Gruzintsev G. A. Emelchenko V. M. Masalov E. E. Yakimov C. Barthou A. Maitre 《Semiconductors》2009,43(2):197-201
The effect of the photonic band gap in the photonic crystal, the synthesized SiO2 opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and the luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide. 相似文献
9.
A. A. Bloshkin A. I. Yakimov V. A. Timofeev A. R. Tuktamyshev A. I. Nikiforov V. V. Murashov 《Semiconductors》2017,51(3):329-334
Admittance spectroscopy is used to study hole states in Si0.7–y Ge0.3Sn y /Si quantum wells in the tin content range y = 0.04–0.1. It is found that the hole binding energy increases with tin content. The hole size-quantization energies in structures containing a pseudomorphic Si0.7–y Ge0.3Sn y layer in the Si matrix are determined using the 6-band kp method. The valence-band offset at the Si0.7–y Ge0.3Sn y heterointerface is determined by combining the numerical calculation results and experimental data. It is found that the dependence of the experimental values of the valence-band offsets between pseudomorphic Si0.7–y Ge0.3Sn y layers and Si on the tin content is described by the expression ΔE V exp = (0.21 ± 0.01) + (3.35 ± 7.8 × 10–4)y eV. 相似文献
10.
G. A. Emel’chenko A. N. Gruzintsev A. B. Kulakov É. N. Samarov I. A. Karpov A. N. Red’kin E. E. Yakimov C. Barthou 《Semiconductors》2007,41(2):176-179
The spectra of spontaneous and stimulated emission of ZnO nanorods grown by two low-temperature procedures are studied. Stimulated emission at 385 nm is observed at room temperature in CVD ZnO nanocrystals pumped by the nitrogen laser radiation at the wavelength 337 nm. The threshold pumping power density for lasing exitonic recombination is ~600 kW/cm2. 相似文献