全文获取类型
收费全文 | 494篇 |
免费 | 32篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 18篇 |
妇产科学 | 1篇 |
基础医学 | 43篇 |
口腔科学 | 13篇 |
临床医学 | 77篇 |
内科学 | 95篇 |
皮肤病学 | 15篇 |
神经病学 | 9篇 |
特种医学 | 149篇 |
外科学 | 45篇 |
综合类 | 11篇 |
预防医学 | 18篇 |
药学 | 45篇 |
中国医学 | 2篇 |
肿瘤学 | 19篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2016年 | 5篇 |
2015年 | 14篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 39篇 |
2006年 | 6篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 17篇 |
1998年 | 28篇 |
1997年 | 32篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 21篇 |
1988年 | 21篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 14篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 1篇 |
排序方式: 共有572条查询结果,搜索用时 93 毫秒
1.
2.
Responses from the surface of the dorsal column nuclei and the dorsal surface of the spinal cord were recorded using monopolar electrodes after stimulation of the lower limbs (common peroneal nerve at the knee and posterior tibial nerve at the ankle) in patients undergoing neurosurgical operations for spasmodic torticollis. Those responses were smaller in amplitude than responses to stimulation of the upper limbs (median nerve at the wrist), and the waveforms differed. The negative deflection that is prominent in the response to stimulation of the upper limbs is more variable, broader, and relatively smaller in amplitude than the response to upper limb stimulation. Another difference between responses to upper and lower limb stimulation was that multiple peaks were superimposed on the initial response to stimulation of the lower limbs, but were not as consistently seen in the responses to upper limb stimulation. The negative peak in the response from the dorsal column nuclei to lower limb stimulation was of about the same latency as the P27 peak in the far-field response (somatosensory evoked potential) to stimulation of the peroneal nerve. 相似文献
3.
4.
The responses recorded from the exposed intracranial portion of the eighth nerve in man with normal hearing to short bursts of low-frequency tones (500, 1000, and 1500 Hz) consist of two components; these two components can be separated by adding and subtracting, respectively, the responses to tonebursts of opposite polarity. Subtracting the responses to tones of opposite polarity reveals a waveform that resembles the sinusoidal waveform of the stimulus (frequency-following response = FFR), while adding the responses to tones of opposite polarity reveals a slow component, the waveform of which is more variable than the frequency-following component. The initial deflection of the slow component of the response to 1000 Hz and to 1500 Hz is a positive peak followed by a slow, negative deflection, and the response to 1500-Hz tonebursts often shows a clear off-response. The slow component of the response to 500-Hz tones often has an initial negative peak followed by a slow, positive or negative wave. The temporal relationship between the stimulus tone and the frequency-following component changes only slightly when the intensity of the sound is changed, whereas the latency of the slow potential decreases with increasing stimulus intensity. The FFR can be masked by noise, and the results of masking with highpass-filtered noise indicate that the frequency-following response may be generated at a location on the basilar membrane that is tuned to a frequency that is higher than that of the stimulus tone. 相似文献
5.
6.
Perforated colorectal neoplasms: correlation of clinical, contrast enema, and CT examinations 总被引:2,自引:0,他引:2
Hulnick DH; Megibow AJ; Balthazar EJ; Gordon RB; Surapenini R; Bosniak MA 《Radiology》1987,164(3):611-615
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm. 相似文献
7.
8.
Coralline hydroxyapatite bone graft substitutes: preliminary report of radiographic evaluation 总被引:1,自引:0,他引:1
A new bone graft substitute made by conversion of the calcium carbonate exoskeleton of reef-building sea coral into hydroxyapatite has recently become clinically available. The normal radiographic appearance of two forms of this material is described. In the immediate postoperative period, the exoskeletal architecture of these implants is readily appreciated. With graft incorporation over the ensuing months, their intrinsic structure is gradually lost in association with poor marginal definition. Evolving radiographic findings reflect the biocompatible nature of these implants, which provides the potential for ingrowth of native bone with preservation of the coralline scaffold, resulting in enhanced biomechanical properties. 相似文献
9.
Forty-two patients with neoplasms involving the cavernous sinus had operations between 1983 and 1987. The lesions included 25 benign tumors (e.g., meningioma, neurilemoma) and 17 malignant tumors (e.g., chondrosarcoma, adenoid cystic carcinoma). The cavernous sinus was entered by inferior, anterolateral, or medial extradural approaches or by superior or lateral intradural approaches. The intracavernous internal carotid artery was managed by dissecting tumor away from it or by occlusion and excision with or without direct vein graft reconstruction, based on the results of a preoperative balloon occlusion test. Cranial nerves III, IV, V, and VI usually were dissected from tumor, but in 3 cases of tumor invasion, the excised nerve segment was reconstructed by direct suture or with a sural nerve interposition graft. Twenty-one of the benign tumors and 8 of the malignant tumors were excised totally and the remainder subtotally. On follow-up ranging from 3 to 48 months, one subtotally excised meningioma recurred and was treated with re-excision and adjuvant radiation therapy. Two "totally" excised malignant tumors recurred outside the cavernous sinus at the margins of excision. There was no operative mortality or permanent cerebral morbidity. Postoperatively, the ocular and neurological function of most patients was similar to the preoperative status; in some, it was significantly improved. Thirteen additional patients with intracavernous neoplasms also were evaluated during the same period and followed without operation. The early follow-up information regarding these patients is provided. 相似文献
10.
Polyketones with carbonyl groups in the polymer backbone (ethylene-carbon monoxide copolymer) have been converted into a novel polyoxime by means of C-nitrosation of the methylene groups and oximation of the carbonyl groups. The polyoxime is considered to be composed largely of 1,2-bis(hydroxyimino)trimethylene units. From the polyoxime and divalent Fe-, Co-, or Ni-salts, polymeric metal chelate complexes were prepared which are capable of combining reversibly with molecular oxygen and, especially the Fe-complex, also with carbon monoxide. 相似文献