全文获取类型
收费全文 | 3379篇 |
免费 | 144篇 |
专业分类
电工技术 | 29篇 |
综合类 | 3篇 |
化学工业 | 668篇 |
金属工艺 | 63篇 |
机械仪表 | 72篇 |
建筑科学 | 92篇 |
矿业工程 | 13篇 |
能源动力 | 56篇 |
轻工业 | 547篇 |
水利工程 | 32篇 |
石油天然气 | 12篇 |
无线电 | 221篇 |
一般工业技术 | 483篇 |
冶金工业 | 856篇 |
原子能技术 | 36篇 |
自动化技术 | 340篇 |
出版年
2023年 | 21篇 |
2022年 | 55篇 |
2021年 | 100篇 |
2020年 | 51篇 |
2019年 | 75篇 |
2018年 | 54篇 |
2017年 | 61篇 |
2016年 | 85篇 |
2015年 | 67篇 |
2014年 | 92篇 |
2013年 | 141篇 |
2012年 | 122篇 |
2011年 | 166篇 |
2010年 | 116篇 |
2009年 | 109篇 |
2008年 | 124篇 |
2007年 | 119篇 |
2006年 | 79篇 |
2005年 | 75篇 |
2004年 | 62篇 |
2003年 | 65篇 |
2002年 | 60篇 |
2001年 | 53篇 |
2000年 | 51篇 |
1999年 | 72篇 |
1998年 | 198篇 |
1997年 | 130篇 |
1996年 | 116篇 |
1995年 | 85篇 |
1994年 | 70篇 |
1993年 | 72篇 |
1992年 | 41篇 |
1991年 | 26篇 |
1990年 | 30篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 30篇 |
1985年 | 40篇 |
1984年 | 29篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1978年 | 22篇 |
1977年 | 41篇 |
1976年 | 43篇 |
1975年 | 23篇 |
1972年 | 28篇 |
1971年 | 20篇 |
1970年 | 25篇 |
1969年 | 18篇 |
排序方式: 共有3523条查询结果,搜索用时 312 毫秒
31.
Welch G. State A. Ilie A. Kok-Lim Low Lastra A. Cairns B. Towles H. Fuchs H. Ruigang Yang Becker S. Russo D. Funaro J. van Dam A. 《Multimedia, IEEE》2005,12(3):22-35
Immersive electronic books (IEBooks) for surgical training will let surgeons explore previous surgical procedures in 3D. The authors describe the techniques and tools for creating a preliminary IEBook, embodying some of the basic concepts. 相似文献
32.
33.
Effects of a supplemental Aspergillus niger-phytase on digestibility and utilization of dietary phosphorus (P) were studied in three experiments with rainbow trout. P concentration in the diets was 4.8 and 5.8 g/kg DM, respectively. The P contained in the diet originated solely from plants, mainly soy-products. Digestibility of P was studied using the stripping method and hydrochloride insoluble ash as marker. Utilization was studied in growth trials by use of the comparative body analysis. At a water temperature of 15 degrees C, both digestibility and utilization of P were increased from 25 to 57% and from 17 to 49%, respectively when 1000 U/kg phytase were supplemented. Feed consumption and gain of trout were significantly increased. At a water temperature of 10 degrees C, utilization of P was also increased from 6 to 25%. However, feed consumption and gain of trout were very low at this water temperature and not influenced by the supplemental phytase. 相似文献
34.
35.
M.R.X. de Barros G. Nykolak D.J. DiGiovanni A. Bruce W.H. Grodkiewicz P.C. Becker 《Photonics Technology Letters, IEEE》1996,8(6):761-763
We report the gain, noise figure, output saturation power, and conversion efficiency of a highly concentrated Er/sup 3+/-doped alumino silicate fiber amplifier. We obtain a gain per unit length of 1.0 dB/cm, which corresponds to the highest gain per unit length obtained in an Er/sup 3+/-doped fiber amplifier. The pump power threshold ranges from 2 to 5 mW, depending on the fiber length. 相似文献
36.
Elaine F. Becker 《乙烯基与添加剂工艺杂志》1996,2(4):321-325
The introduction of low-price color systems, both quality control and color formulation, has brought affordability and practicality to the medium and small plastics companies. While color systems today are faster, cheaper, more accurate, easier to use than ever before, they are not that much more successful at doing what they were designed to do than they were 25 years ago. The pitfalls of start-up and implementation and the people problems have changed very little and are still a major factor in determining the degree of success. This paper discusses the ramifications of who is chosen to implement the system, what their charter is, and the resources that they are given. Factors to be considered and creating the right environment when implementing a color system are discussed. Some suggestions for planning a successful start-up and installation are given. 相似文献
37.
U. Lembke K. Grosse R. Pascova I. Gutzow O. Becker L. Horn 《Journal of Materials Science》1996,31(16):4333-4346
The kinetics of silver chloride cluster formation in a sodium borate glass heat treated isothermally at different temperatures above the glass transition temperature has been studied with small-angle X-ray scattering (SAXS). It is established that the size distributions of particle number and particle volume have bimodal shapes, i.e. the system of AgCl droplets consists of two populations with significantly different mean radii. The bimodality of the size distribution functions is confirmed by results of transmission electron microscopy (TEM) even if different techniques of sample preparation are used. The resolution limits of the TEM techniques applied amount to 2 nm and are comparable with the smallest particle diameters detectable by the SAXS method. The evolution of the size distributions is discussed in the framework of the theories of nucleation, growth and Ostwald ripening. 相似文献
38.
FJ Martinez I Stanopoulos R Acero FS Becker R Pickering JF Beamis 《Canadian Metallurgical Quarterly》1994,105(1):168-174
The evaluation of dyspnea is problematic when a cause is inapparent after initial diagnostic studies. We examined the results and role of cardiopulmonary exercise testing (CPET) in 50 patients with a mean 23 months of dyspnea and normal FEV1 and FVC. The CPET studies were interpreted by a panel and a consensus reached. Subsequent tests ordered by the primary physician were reviewed, and a final diagnosis was agreed on by the panel. Seven of 50 patients had cardiac limitation, 17 of 50 had pulmonary limitation, 14 of 50 had obesity and/or deconditioning, 1 of 50 had gastroesophageal reflux, and 16 of 50 had either psychogenic dyspnea or no identifiable disease. Five patients had more than one clinical diagnosis accounting for 55 diagnoses in the 50 patients. Those with a normal CPET had a higher VO2max and O2 pulse than those with cardiac disease, deconditioning, or hyperactive airways disease (HAD) (p < 0.05). Electrocardiographic changes identified cardiac disease while studies demonstrating ventilatory limitation identified a pulmonary process. In 24, deconditioning could not be distinguished from cardiac limitation. Of these, 14 responded to exercise training and/or weight loss, whereas 3 had cardiac disease, 7 had HAD, and 4 had psychogenic dyspnea (4 had more than one clinical diagnosis). In the 13 patients with normal CPET results, one had gastroesophageal reflux, two had HAD, four had psychogenic dyspnea, and six had no identifiable disease. We conclude that a diagnosis can be made in most patients with chronic dyspnea; however, further studies including bronchoprovocation are often required. Cardiopulmonary exercise testing is useful in identifying a cardiac or pulmonary process, but it is insensitive in distinguishing cardiac disease from deconditioning. 相似文献
39.
Ws/Ws rats are deficient in both mucosal- and connective tissue-type mast cells. To study the role of mast cells in active anaphylaxis, changes in vascular permeability in the trachea upon intravenous antigen challenge with Evans blue dye were examined in Ws/Ws, heterogenic Ws/+, and normal +/ + rats sensitized with the nematode Nippostrongylus brasiliensis. Antigen challenge resulted in fatal anaphylactic shock in some +/+ and Ws/+ rats, but not in Ws/Ws rats. Marked dye leakage developed within 30 min in the trachea of +/+ and Ws/+ rats, while Ws/Ws rats showed no substantial increases in the levels of vascular permeability. Ex vivo stimulation of sensitized lung fragments from +/+ animals with specific antigen induced significant releases of histamine and leukotriene (LT) C4, while sensitized Ws/Ws rat-lung fragments did not. In Ws/Ws rats, levels of nematode-specific IgE, IgG1 and IgG2a antibodies as well as levels of lung eosinophilia were not significantly different from those in +/+ rats. These results show that mast cell-deficient Ws/Ws rats fail to develop active anaphylaxis, and this is mediated probably by the lack of mast cell-derived mediators required for initiation of the reaction. 相似文献
40.
D Becker Y Razskazovskii MU Callaghan MD Sevilla 《Canadian Metallurgical Quarterly》1996,146(4):361-368
A major problem in the intensive care unit nowadays is the development of multiple organ dysfunction syndrome (MODS), a cumulative sequence of progressive deterioration of organ functions. While the pathogenic pathways of MODS remain to be elucidated, it is assumed that cells of the host defence system, especially the macrophages, are altered in their function. During the development of MODS it is assumed that macrophages are overactivated and that an exaggerated inflammatory response may contribute to its pathogenesis. In order to gain insight into the alterations of the functional status of the macrophage during the development of MODS, a series of macrophage functions was measured in the subsequent phases of zymosan induced generalized inflammation in mice. Male C57BL/6 mice received a single dose of zymosan intraperitoneally and groups of animals were killed after 2, 5, 8, and 12 days. Peritoneal macrophages were collected for in vitro assessment of the ADCC, the production of superoxide (O2-) and nitric oxide (NO), and complement mediated phagocytosis and intracellular killing of Staphylococcus aureus. A single intraperitoneal injection with zymosan resulted in a three-phase illness. During the third phase the animals developed MODS-like symptoms. Peritoneal cells from control animals produced very low to non-detectable amounts of O2- and NO, and the cytotoxic activity was also low. During the development of MODS, from day 7 onwards, the ability to produce O2- and NO2- became strongly elevated, as did the cytotoxic activity. These findings are in parallel with the development of MODS whereas the phagocytic and killing capacity remained essentially unaltered. The changes found could be detrimental for the organism, thus possibly contributing to the onset and development of MODS. 相似文献