全文获取类型
收费全文 | 7434篇 |
免费 | 754篇 |
国内免费 | 2篇 |
出版年
2022年 | 49篇 |
2021年 | 127篇 |
2020年 | 71篇 |
2019年 | 76篇 |
2018年 | 89篇 |
2017年 | 71篇 |
2016年 | 155篇 |
2015年 | 299篇 |
2014年 | 303篇 |
2013年 | 436篇 |
2012年 | 557篇 |
2011年 | 519篇 |
2010年 | 299篇 |
2009年 | 249篇 |
2008年 | 430篇 |
2007年 | 461篇 |
2006年 | 397篇 |
2005年 | 351篇 |
2004年 | 348篇 |
2003年 | 326篇 |
2002年 | 328篇 |
2001年 | 120篇 |
2000年 | 90篇 |
1999年 | 100篇 |
1998年 | 102篇 |
1997年 | 67篇 |
1996年 | 63篇 |
1995年 | 52篇 |
1994年 | 75篇 |
1993年 | 67篇 |
1992年 | 68篇 |
1991年 | 58篇 |
1990年 | 79篇 |
1989年 | 55篇 |
1988年 | 52篇 |
1986年 | 40篇 |
1985年 | 61篇 |
1984年 | 53篇 |
1983年 | 54篇 |
1982年 | 60篇 |
1981年 | 51篇 |
1980年 | 41篇 |
1979年 | 46篇 |
1978年 | 42篇 |
1977年 | 42篇 |
1976年 | 39篇 |
1975年 | 43篇 |
1974年 | 41篇 |
1973年 | 37篇 |
1970年 | 39篇 |
排序方式: 共有8190条查询结果,搜索用时 31 毫秒
91.
92.
Ruth Lotmar W. R. Ranscht-Froemsdorff H. Weise 《International journal of biometeorology》1969,13(3-4):231-238
Zusammenfassung In einem gegen die natürliche Langwellenstrahlung abgeschirmten Versuchsraum wurde die Atmung von Mäuselebergewebe in künstlich erzeugten elektromagnetischen Feldern gemessen. Unter der Einwirkung von zyklonale Wetterlagen simulierenden Programmen (30–100 pulses sec–1, > 100 mV m–1, 10–100 kHz) ergab sich im Vergleich zu den Kontroll-QO2-Werten eine signifikante Dämpfung der Gewebeatmung um 42% ± 2,8% (p<0,001). Die Applikation eines H-Feld-Programms blieb ohne Wirkung. Programme mit Simulierung antizyklonaler Wetterlagen(1–3 pulses sec–1, <10 mV m–1, 10 kHz) hatten ebenfalls keinen Einfluss auf die Atmungsgeschwindigkeit der Mäuseleber.
In a room completely shielded against long wave radiation, liver tissue of mice in a Warburg apparatus was exposed to artificial electromagnetic radiation simulating cyclonic and anticyclonic weather. Under the influence of simulated cyclonic weather programs (30–100 pulses sec–1, > 100 mV m–1 10–100 kHz) a significant decrease (42% ± 2,8%) of the respiration rate of the liver tissue was found, compared with the control QO2 (p < 0,001). The application of a cyclonic weather H-field program had no effect. Simulated anticyclonic weather (1–3 pulses sec–1, < 10 mV m–1, 10 kHz) also failed to produce a demonstrable effect on the respiration rate of mouse liver tissue.
Resume Dans un local absolument protégé contre l'irradiation naturelle par ondes longues, des tissus de foie de souris ont été exposés, dans un appareil de Warburg, à des impulsions électromagnétiques artificielles, correspondant à celles de temps cyclonal et anticyclonal. Sous l'influence des programmes artificiels simulant le temps cyclonal(30–100 pulses sec–1, > 100 mV m–1, 10–100 kHz), il a été constaté une inhibitation significative de la respiration tissulaire de 42% ± 2,8% comparée aux valeurs du QO2 de contrôle (p < 0.001). L'application d'un temps cyclonal-"H-field"-programme séparé, est demeuré sans effet. De même. les signaux de temps anticyclonal(1–3 pulses sec–1, < 10 mV m–1, 10 kHz), n'ont eu aucune influence démonstrable sur la vitesse de respiration du fois de souris.相似文献
93.
Deoxyribonucleic Acid Base Compositions of Selected Mycoplasmas and L-Phase Variants 总被引:3,自引:1,他引:2 下载免费PDF全文
Deoxyribonucleic acid base compositions were determined for 25 Mycoplasma strains and 6 L-phase variant strains. Values obtained correlated well with the results of other investigators. 相似文献
94.
Development Genes and Evolution - 相似文献
95.
Studies on dog heartworm in South Texas 总被引:1,自引:0,他引:1
H L Keegan C M Fitzgerald T L McCrary M D Doyle 《Texas reports on biology and medicine》1968,26(3):321-330
96.
Ruth C. Steinkamp Clarence L. Young Dolores Nyhus Arnold E. Greenberg 《The Western journal of medicine》1968,109(2):126-133
The amount of sodium ion in water used for ingestion may be critical in effective use of a low sodium dietary regimen. Waters containing not over 20 mg of sodium per liter are provided for in the sodium restricted diets set forth by the American Heart Association. For diets containing more than 500 mg of sodium a day, waters of greater sodium content may be used if proper dietary adjustments are made.While assessment of the long-term average sodium content of a community water supply is difficult, the determined values for sodium lend to classification within range categories. The larger community water supplies in California are presented within several range categories of sodium content.The more commonly used water softeners add sodium to water. The sodium-restricted patient should be cautioned against their use. Similar consideration should probably be given to water supplies of retirement communities where the potential for disorders requiring sodium restriction is greater than in the general population. 相似文献
97.
THE DEGENERATIVE CHANGES IN PANCREATIC ACINAR CELLS CAUSED BY DL-ETHIONINE 总被引:24,自引:3,他引:21 下载免费PDF全文
Degeneration of pancreatic acinar cells in rats injected with ethionine was studied by electron microscopy. The most conspicuous morphologic lesions occurred in the ergastoplasm. There was a widening of the endoplasmic reticulum, a decrease in number of membrane-associated ribosomes, and a development of fine and coarse vacuoles containing agranular disoriented membranes. Cytoplasmic ribosomes unassociated with membranes were less numerous. Nuclear changes consisted of a coarsening and clumping of the nuclear chromatin, chromatin margination, and increased osmiophilia and vacuolation of the nucleolus. Eight to ten days after the beginning of ethionine injections, changes in zymogen granules, mitochondria, and the Golgi apparatus appeared, but only after extensive damage to the acinar cell. The effects were consistent with ethionine's known interference with protein metabolism but also suggest disturbance in ribonucleic acid metabolism. The ergastoplasmic changes after ethionine were similar in some respects to the early lesions produced in liver parenchymal cells by fasting, to the changes occurring in animals on protein-free diets, or to some of the liver changes produced by azo dye carcinogens. The ribosomal and ergastoplasmic changes represent early morphologic expressions of the biochemical effect of ethionine. 相似文献
98.
D. M. McLean E. Joan Quantz Ruth D. Bach B. Mae Pevzner R. P. B. Larke G. A. McNaughton 《CMAJ》1964,90(25):1390-1393
Virological investigations of 115 children with the aseptic meningitis syndrome during 1963 resulted in the isolation of enteroviruses from cerebrospinal fluid (CSF) and/or feces of 21 of 48 children who had no association with mumps. For the third successive year, Echo 9 was the dominant enterovirus in cases of aseptic meningitis in Toronto children, but no rashes were associated with Echo 9 meningitis during 1963, in contradistinction to previous years. Mumps virus was isolated from CSF of 25 patients by inoculation of rhesus monkey kidney cultures, and rising or elevated mumps antihemagglutinin titres in paired sera from a further 33 cases provided laboratory evidence of infection with mumps virus in 58 of 67 patients with mumps meningoencephalitis. No enlargement of salivary glands was noted in 20 laboratory-proved cases of mumps meningoencephalitis. Enteroviral meningitis occurred principally during summer, but the peak of mumps meningoencephalitis occurred during late winter. 相似文献
99.
We have examined the nature of the circular dichroism band at 330 mμ for a series of copolymers of β-p-nitrobenzyl L -aspartate with β-benzyl L -aspartate. The circular dichroism band arises from an electronic transition in the nitroaromatic group. In order to interpret the effect quantitatively, we employed a simplified statistical treatment and curve fitting for six copolymers. Both approaches gave consistent results, which indicates that the dichroism comes from pairwise interactions between two nitrobenzyl groups. We constructed a molecular model that meets the constraints and requirements of the analyses developed in this paper. In this model, it is proposed that the main chain forms a right-handed α-helix and that nitrobenzyl groups separated by four residues interact with each other. 相似文献
100.
Zusammenfassung Es werden verschiedene Typen von Einschlußkörperchen im Karyoplasma der Epithelzellen des menschlichen Nebenhodenepithels beschrieben. Die verschieden strukturierten Kerninklusionen werden als eine Differenzierungsreihe aufgefaßt. Sie beginnt mit kleinen rundlichen Körperchen aus feinfädigem Material und führt über die Ausbildung von Anhäufungen dichter homogener Kugeln zu großen Vakuolen wechselnden Inhaltes.
Herrn Professor Dr. W. Bargmann zum 60. Geburtstag gewidmet.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
Summary Different types of inclusion bodies are described in the karyoplasm of the epithelial cells of the human epididymis. The structural differences between these inclusions are interpreted as being indicative of consecutive stages in the process of their formation. Thus small, spherical bodies consisting of a fine fibrous material are believed to be the initial stages in the formation of the inclusion bodies whereas the dense, homogenous globules are thought to represent a later stage. Large vacuoles containing different materials are regarded as the final stage in this process of differentiation.
Herrn Professor Dr. W. Bargmann zum 60. Geburtstag gewidmet.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献