全文获取类型
收费全文 | 886398篇 |
免费 | 72157篇 |
国内免费 | 1914篇 |
专业分类
耳鼻咽喉 | 13004篇 |
儿科学 | 25240篇 |
妇产科学 | 25516篇 |
基础医学 | 127831篇 |
口腔科学 | 25796篇 |
临床医学 | 77563篇 |
内科学 | 170416篇 |
皮肤病学 | 17624篇 |
神经病学 | 72129篇 |
特种医学 | 35908篇 |
外国民族医学 | 174篇 |
外科学 | 139634篇 |
综合类 | 24844篇 |
现状与发展 | 2篇 |
一般理论 | 289篇 |
预防医学 | 68677篇 |
眼科学 | 20994篇 |
药学 | 66216篇 |
1篇 | |
中国医学 | 1648篇 |
肿瘤学 | 46963篇 |
出版年
2018年 | 7729篇 |
2015年 | 8111篇 |
2014年 | 11673篇 |
2013年 | 17643篇 |
2012年 | 24013篇 |
2011年 | 25253篇 |
2010年 | 14745篇 |
2009年 | 13953篇 |
2008年 | 23946篇 |
2007年 | 26156篇 |
2006年 | 26037篇 |
2005年 | 25775篇 |
2004年 | 25196篇 |
2003年 | 24258篇 |
2002年 | 23351篇 |
2001年 | 36193篇 |
2000年 | 36772篇 |
1999年 | 31249篇 |
1998年 | 9580篇 |
1997年 | 8862篇 |
1996年 | 8752篇 |
1995年 | 8266篇 |
1994年 | 7959篇 |
1992年 | 26948篇 |
1991年 | 26367篇 |
1990年 | 25858篇 |
1989年 | 24906篇 |
1988年 | 23422篇 |
1987年 | 23077篇 |
1986年 | 21953篇 |
1985年 | 21294篇 |
1984年 | 16578篇 |
1983年 | 14182篇 |
1982年 | 9059篇 |
1981年 | 8418篇 |
1980年 | 7844篇 |
1979年 | 16865篇 |
1978年 | 12235篇 |
1977年 | 10308篇 |
1976年 | 9431篇 |
1975年 | 10246篇 |
1974年 | 12734篇 |
1973年 | 12221篇 |
1972年 | 11621篇 |
1971年 | 10767篇 |
1970年 | 10275篇 |
1969年 | 9953篇 |
1968年 | 8948篇 |
1967年 | 8285篇 |
1966年 | 7709篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
W. Janzarik 《Der Chirurg》2004,75(11):1053-1055
Zusammenfassung Die genauere Bestimmung von Leitfunktionen soll das früher zum strukturdynamischen Ansatz Gesagte ergänzen, korrigieren und zum Abschluss bringen. Auf vormenschlichen Entwicklungsstufen geht es um die autopraktischen Antriebe der Lebensbewegung und ihre instinktive Hemmung und Aktivierung. Auf der menschlichen Ebene hat sich die Richtung der Antriebe differenziert. Ihre Autopraxis als das bewegende Prinzip ist geblieben. Hemmung und Aktivierung sind in die Entwicklung einer Innenwelt und ihres strukturellen Hintergrundes einbezogen worden und haben sich aus der instinktiven Abhängigkeit gelöst. An der Funktion der Aktivierung hat sich wenig geändert. Hemmung hat sich in die komplexe Funktion der Desaktualisierung ausgeweitet; sie greift als steuerndes Prinzip in das autopraktische Geschehen ein. Abschließend werden mit einem Exkurs in die Willensthematik die Funktionen von Autopraxis, Desaktualisierung und Aktivierung in ihrem Zusammenwirken erläutert.
相似文献
相似文献
993.
994.
Ch. Offergeld J. Kromeier A. Aschendorff W. Maier Th. Klenzner Th. Beleites Th. Zahnert J. Schipper R. Laszig 《European archives of oto-rhino-laryngology》2007,264(4):345-351
Imaging is an essential diagnostic tool in reconstructive middle ear surgery, especially in pre-operative planning. Due to ongoing improvement of imaging quality and development of new imaging techniques like e.g. rotational tomography (RT) post-operative follow-up and immediate evaluation of surgical results may become more important. The aim of this experimental study was to evaluate RT as a new tool for postoperative determination of middle ear anatomy and implant position in temporal bones. RT was performed in ten temporal bone specimen after insertion of different middle ear prostheses concerning material, shape and length (PORP; TORP; Stapes piston). An implantable hearing device (Symphonix Soundbridge®) was also implanted and visualized. For comparison some specimen additionally underwent conventional computed tomography (CT), including the newest technology. Characterization of anatomical structures of the temporal bone using RT was of comparable quality to conventional CT-scans in all investigated specimen while requiring approximately 30% of the CT’s irradiation exposure. Unlike CT the RT showed almost no problems due to metallic artefacts of the implanted prostheses. Furthermore RT enabled a 3-dimensional view of the temporal bone and angle determination of inserted prostheses towards the tympanic membrane and/or the malleus handle. Detailed imaging of the prostheses allowed determination of shape, material and localization within the specimen’s reconstructed middle ear. The new imaging technique of RT allows precise presentation of anatomical structures and middle ear implants in temporal bones. Following these experimental results it will be our future work to evaluate this method in clinical practise. 相似文献
995.
996.
Prof. Dr. W.A. Scherbaum 《Der Diabetologe》2007,3(4):259-260
997.
W. N. Charman 《Ophthalmic & physiological optics》2006,26(1):5-12
In the Cardiff acuity test, simple pictures on an otherwise neutral grey card are defined by borders consisting of a relatively broad white band flanked by black bands each half the width of the white band. Higher levels of acuity correspond to the ability to detect figures defined by narrower borders, the figure size remaining constant. It is sometimes implied that the acuity limit corresponding to each card can be equated with different levels of grating resolution, the total width of the border corresponding to the overall grating period. It is shown that although the spatial frequency spectra of the Cardiff figures, like those of other vanishing optotypes, lack very low-frequency components, they have a complex two-dimensional form. The figures have wide spatial bandwidth and no well-defined discrete frequency components. As a result, the relationship between measured Cardiff and grating acuity will vary somewhat, depending upon the particular optical, neural or other deficits of the individual being tested. 相似文献
998.
As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 ± 0.3 vs. 2.2 ± 0.3 cps) and human semen (5.0 ± 0.3 vs. 4.3 ± 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 ± 0.7 vs. 96.8 ± 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 ± 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen. 相似文献
999.
W. B. Quay 《Journal of neural transmission (Vienna, Austria : 1996)》1981,52(1-2):107-115
Summary Quantitative aspects of the microanatomy of the pineal gland and other neuroendocrine and circumventricular structures were studied in a small, reproductively suppressed, female Naked Mole-rat from central Kenya, Africa. The atrophic pineal is the smallest in absolute size (0.002135 mm3) of any so far described in a species of rodent, and in size relative to body weight is second only to that of another tropical species. The subcommissural organ and posterior collicular recess are also relatively small and less well differentiated than those in most other examined rodent species. In contrast, the subfornical organ, OVLT and median eminence are large and well vascularized. It is concluded that the pineal in this species follows the previously described trend among rodents of relatively smaller size in species whose centers of distribution are in lower latitudes. Although the pineal is atrophic, the Naked Mole-rat still exhibits 24-hour and seasonally timed patterns of behavior and seasonal reproduction. However, in this species these events are probably cued by moisture, temperature and social factors rather than by photic information. 相似文献
1000.
David C Todd Beth E Davis Audrey J Smycniuk Donald W Cockcroft 《Annals of allergy, asthma & immunology》2005,94(1):45-47
BACKGROUND: We have observed that dosimeter-run nebulizers have a much smaller output when manually activated than when breath activated; however, this has not been adequately investigated. OBJECTIVE: To evaluate the effect of different calibration methods on nebulizer output. METHODS: Six healthy subjects performed all calibrations. The nebulizers were operated by 2 different dosimeters and were calibrated to produce 9 microL per actuation by breath activation followed by exhalation to the room. The nebulizers were then operated at these identical settings, and the output determined in 3 ways: (1) breath activation followed by exhalation to the room, (2) breath activation with exhalation into the nebulizer, and (3) manual activation (with no subject using the nebulizer). These 3 methods were termed regular, rebreathe, and manual, respectively. RESULTS: There was a large and statistically significant difference in nebulizer output among the 3 methods. The measured rebreathe outputs (5.6 and 5.7 microL per actuation) were approximately two thirds and the manual outputs (3.2 and 3.9 microL per actuation) were approximately one third of the regular calibration outputs (8.6 and 8.9 microL per actuation); the 2 values are for the 2 dosimeters. The results were highly statistically significant (P < .001). CONCLUSIONS: The method by which a nebulizer-dosimeter system is calibrated results in different nebulizer outputs. This has a high likelihood of influencing the concentration of methacholine causing a 20% decrease in volume in the first second of forced expiration. 相似文献