全文获取类型
收费全文 | 58700篇 |
免费 | 2194篇 |
国内免费 | 62篇 |
专业分类
电工技术 | 354篇 |
综合类 | 40篇 |
化学工业 | 10701篇 |
金属工艺 | 932篇 |
机械仪表 | 967篇 |
建筑科学 | 1496篇 |
矿业工程 | 99篇 |
能源动力 | 1293篇 |
轻工业 | 8373篇 |
水利工程 | 448篇 |
石油天然气 | 217篇 |
武器工业 | 10篇 |
无线电 | 1894篇 |
一般工业技术 | 7556篇 |
冶金工业 | 19780篇 |
原子能技术 | 277篇 |
自动化技术 | 6519篇 |
出版年
2024年 | 125篇 |
2023年 | 396篇 |
2022年 | 837篇 |
2021年 | 1305篇 |
2020年 | 940篇 |
2019年 | 1116篇 |
2018年 | 1633篇 |
2017年 | 1633篇 |
2016年 | 1732篇 |
2015年 | 1362篇 |
2014年 | 1735篇 |
2013年 | 3450篇 |
2012年 | 2710篇 |
2011年 | 2915篇 |
2010年 | 2277篇 |
2009年 | 2188篇 |
2008年 | 2016篇 |
2007年 | 1790篇 |
2006年 | 1382篇 |
2005年 | 1224篇 |
2004年 | 1127篇 |
2003年 | 1011篇 |
2002年 | 934篇 |
2001年 | 673篇 |
2000年 | 667篇 |
1999年 | 994篇 |
1998年 | 6230篇 |
1997年 | 3950篇 |
1996年 | 2546篇 |
1995年 | 1467篇 |
1994年 | 1182篇 |
1993年 | 1356篇 |
1992年 | 346篇 |
1991年 | 412篇 |
1990年 | 309篇 |
1989年 | 345篇 |
1988年 | 347篇 |
1987年 | 296篇 |
1986年 | 249篇 |
1985年 | 273篇 |
1984年 | 172篇 |
1983年 | 144篇 |
1982年 | 209篇 |
1981年 | 227篇 |
1980年 | 256篇 |
1979年 | 98篇 |
1978年 | 119篇 |
1977年 | 534篇 |
1976年 | 1191篇 |
1973年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Bravo-Montes J. A. Martín-Toledano A. Sánchez-Macián A. Ruano O. Garcia-Herrero F. 《The Journal of supercomputing》2022,78(6):8056-8080
The Journal of Supercomputing - CMOS technology is facing physical limitations in scaling the manufacturing process. Therefore, to deepen the development of better designs in a smaller area, it is... 相似文献
152.
R.?KovácsEmail authorView authors OrcID profile P.?Ván 《International Journal of Thermophysics》2016,37(9):95
Heat conduction at low temperatures shows several effects that cannot be described by the Fourier law. In this paper, the performance of various theories is compared in case of wave-like and ballistic propagation of heat pulses in NaF. 相似文献
153.
Amino acid changes S180A (S-->A at site 180), H197Y, Y277F, T285A, and A308S are known to shift the maximum wavelength of absorption (lambda max) of red and green visual pigments toward blue, essentially in an additive fashion. To test the generality of this "five-sites" rule, we have determined the partial amino acid sequences of red and green pigments from five mammalian orders (Artiodactyla, Carnivora, Lagomorpha, Perissodactyla, and Rodentia). The result suggests that cat (Felis catus), dog (Canis familiaris), and goat (Capra hircus) pigments all with AHYTA at the five critical sites have lambda max values of approximately 530 nm, whereas rat (Rattus norvegicus) pigment with AYYTS has a lambda max value of approximately 510 nm, which is accurately predicted by the five-sites rule. However, the observed lambda max values of the orthologous pigments of European rabbit (Oryctolagus cuniculus), white-tailed deer (Odocoileus virginianus), gray squirrel (Sciurus carolinensis), and guinea pig (Cavia procellus) are consistently more than 10 nm higher than the predicted values, suggesting the existence of additional molecular mechanisms for red and green color vision. The inferred amino acid sequences of ancestral organisms suggest that the extant mammalian red and green pigments appear to have evolved from a single ancestral green-red hybrid pigment by directed amino acid substitutions. 相似文献
154.
Cordero-Dávila A Luna-Aguilar E Vázquez-Montiel S Zárate-Vázquez S Percino-Zacarias ME 《Applied optics》1998,37(4):672-675
We use a square grid in the Ronchi test. This grid allows processing of both the X and the Y directions when calculating optical path difference. We use trapezoidal integration to analyze the new patterns, since it does not have the smoothing drawback at the edges of the wave front. 相似文献
155.
Dr. Z. Zemánek 《Acta Mechanica》1996,115(1-4):151-159
Summary The use of holographic interferometry for the measurement of large deformations is described. From the nature of holographic interferometry it is evident that large deformations exceed the wave length of the light source used by at least ten times of this size. To obtain holographically identifiable values of large deformations, a method of successive partial lighting is used. It shows how it is possible to keep all the advantages of the holographic method and use it even under conditions which apparently exceed its possibilities of application. 相似文献
156.
The universal bio-optical algorithm of the Coastal Zone Color Scanner (CZCS) for case I waters implicitly contains an average covariance of the absorption by phytoplankton and colored dissolved organic matter (CDOM) and detritus. We made that covariance explicit by combining the CZCS algorithm with an expression for reflectance. The spectral variation of absorption by CDOM plus detritus for case I waters may be estimated by the expression a(gd(λ)) = 2a(ph)(443)*chl{exp[-0.013(λ - 443)]. 相似文献
157.
158.
S. Rodríguez C. Lafuente J. A. Carrión F. M. Royo J. S. Urieta 《International Journal of Thermophysics》1996,17(6):1281-1288
Excess Volumes,V
E, and excess viscosities,
E, at 293.15 and 313.15 K are reported for binary mixtures of some cyclic ethers (tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran and 2,5-dimethyltetrahydrofuran) + bromocyclohexane. These properties were obtained from density and viscosity measurements.
E and
E show negatives values for all the mixtures. 相似文献
159.
JA Ortu?o-Cortés L Quintana-Tomás A García-García 《Canadian Metallurgical Quarterly》1996,19(2):47-51
1.5% Capsaicin (Cap) or Vehicle was respectively used to treat the right or left sciatic nerve in 20 Sprague-Dawley rats. On the seventh day, the 20 rats were at random divided into electroacupuncture (EA) group and non-EA group, the spinal cord corresponding to the afferent segments of sciatic nerve was taken out for observing the changes of acetylcholinesterase (AChE) activity and [3H]-quinuelidinylbenzylate (QNB) binding sites in the spinal dorsal horn (SDH). The results were as follows: (1) EA "Huantiao" could enhance AChE activity in the SDH and decrease [3H]-QNB binding sites; (2) Cap treating sciatice nerve could weaken AChE activity in the SDH and merease [3H]-QNB binding sites; (3) Cap treatment could inhibit or partially inhibit the actions of EA as above. The results indicated that ACh participated in the primary afferent of acupuncture information and might exist in Cap-sensitive neurons. 相似文献
160.
E Maganto Pavón 《Canadian Metallurgical Quarterly》1996,20(6):522-533
In spite of the names and works of practically all the early 19th Century Spanish specialists in urinary tract being widely known, there are still in my opinion several names and writings, either forgotten or misplaced in newspaper libraries, archives and general libraries, awaiting to be discovered. The second half of the 19th Century was a prolific age in every aspect of Spanish life, most particularly literature. In Medicine, apart from the well known professional writings, the number of scientific journals and publications, whether in the form of brochures or divulgative articles, that came to light was countless. Computer management of collections currently under implementation in many registers, will allow their location and the finding of new texts. One of these long forgotten pioneers, is Doctor Alejandro Settier (1858-1915), a Valencian practitioner who describes himself as a "disciple of the Paris hospitals and specialist in genitourinary tract disorders", who practised in Madrid between 1883 and 1890. Surprisingly, and in spite of him being the most prolific author in urological issues during the last century (my investigations show he is the author of 2 books, 3 brochures and 40 articles in journals), neither his name nor his work, as far as we know, are mentioned by none of the historians consulted, which is nothing but highly surprising if we also take into consideration that Alejandro Settier was the founder of the first Spanish monographic journal for urinary disorders: "Gaceta de enfermedades de los órganos génito-urinarios" (Gazette of genitourinary organs disorders), Madrid 1887, which in spite of its short existence, can be considered as the first scientific periodical publication in our specialty. 相似文献