全文获取类型
收费全文 | 5976篇 |
免费 | 619篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 231篇 |
儿科学 | 146篇 |
妇产科学 | 144篇 |
基础医学 | 293篇 |
口腔科学 | 181篇 |
临床医学 | 865篇 |
内科学 | 765篇 |
皮肤病学 | 63篇 |
神经病学 | 321篇 |
特种医学 | 167篇 |
外科学 | 2330篇 |
综合类 | 33篇 |
一般理论 | 1篇 |
预防医学 | 148篇 |
眼科学 | 449篇 |
药学 | 161篇 |
中国医学 | 16篇 |
肿瘤学 | 303篇 |
出版年
2023年 | 78篇 |
2022年 | 21篇 |
2021年 | 97篇 |
2020年 | 132篇 |
2019年 | 85篇 |
2018年 | 185篇 |
2017年 | 171篇 |
2016年 | 184篇 |
2015年 | 186篇 |
2014年 | 342篇 |
2013年 | 391篇 |
2012年 | 272篇 |
2011年 | 269篇 |
2010年 | 320篇 |
2009年 | 396篇 |
2008年 | 259篇 |
2007年 | 204篇 |
2006年 | 264篇 |
2005年 | 178篇 |
2004年 | 137篇 |
2003年 | 121篇 |
2002年 | 107篇 |
2001年 | 120篇 |
2000年 | 78篇 |
1999年 | 86篇 |
1998年 | 128篇 |
1997年 | 148篇 |
1996年 | 132篇 |
1995年 | 138篇 |
1994年 | 119篇 |
1993年 | 106篇 |
1992年 | 109篇 |
1991年 | 96篇 |
1990年 | 62篇 |
1989年 | 90篇 |
1988年 | 87篇 |
1987年 | 64篇 |
1986年 | 61篇 |
1985年 | 49篇 |
1984年 | 49篇 |
1983年 | 34篇 |
1982年 | 41篇 |
1981年 | 35篇 |
1980年 | 29篇 |
1979年 | 26篇 |
1978年 | 17篇 |
1962年 | 16篇 |
1956年 | 28篇 |
1955年 | 22篇 |
1954年 | 16篇 |
排序方式: 共有6617条查询结果,搜索用时 62 毫秒
71.
An unusual giant cell tumor of the breast of a 72 year old man is reported. The microscopic and ultrastructural features of the tumor are presented in detail. Unusual and previously unreported myofibroblastic and myoepithelial differentiation of the spindle cell component is described. The possible histogenesis of the tumor is discussed. 相似文献
72.
Riitta Hari Ritva Hänninen Timo Mäkinen Veikko Jousmäki Nina Forss Mika Seppä Oili Salonen 《Neuroscience letters》1998,240(3):998-134
We describe patient E.P. who occasionally perceives a ‘ghost' hand which copies the previous positions of the left hand with a 0.5–1 min time lag, but follows the movement patterns of the right hand. The symptoms started after an operation of a ruptured aneurysm, followed by an infarction of the right frontal lobe; E.P. also has a previously lesioned corpus callosum. Neuromagnetic recordings revealed that activity of the left secondary somatosensory cortex was strongly suppressed during the ghost arm percept, thereby providing an objective correlate for E.P.'s sensations. We conclude that simultaneous mental contents about body scheme may be based on neural information extracted at considerably different times, resulting in fragmentation of bodily awareness. 相似文献
73.
BACKGROUND: Immunotherapy with Hymenoptera venoms is highly effective but causes allergic side-effects frequently, especially when honeybee venom is used. Therefore, our objective was to investigate the effect of pretreatment with the antihistamine fexofenadine on the incidence of allergic side-effects during ultrarush immunotherapy with bee venom. METHODS: In a double-blind, placebo-controlled trial, 57 patients with a history of systemic allergic reactions to honeybee stings and positive diagnostic tests (skin tests, serum specific IgE to honeybee venom) were investigated. Bee venom immunotherapy was started with an ultrarush protocol and patients were randomized to pretreatment with either fexofenadine 180 mg or placebo on days 1, 8, 22, and 50 of the protocol. Local and systemic allergic side-effects were registered. RESULTS: Fifty-four patients completed the study, 28 on fexofenadine and 26 on placebo pretreatment. On day 1, large local reactions were significantly reduced in both extension and duration by fexofenadine pretreatment (P<0.025). Systemic allergic side-effects on the whole were not reduced. However, the symptoms pruritus, urticaria, and angioedema occurred less frequently with fexofenadine (P<0.05). CONCLUSIONS: Pretreatment with fexofenadine during venom immunotherapy reduces local allergic reactions and generalized symptoms of the urticaria and angioedema type. 相似文献
74.
N. Forss R. Hari R. Salmelin A. Ahonen M. Hämäläinen M. Kajola J. Knuutila J. Simola 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1994,99(2):309-315
We recorded somatosensory evoked magnetic fields from ten healthy, right-handed subjects with a 122-channel whole-scalp SQUID magnetometer. The stimuli, exceeding the motor threshold, were delivered alternately to the left and right median nerves at the wrists, with interstimulus intervals of 1, 3, and 5 s. The first responses, peaking around 20 and 35 ms, were explained by activation of the contralateral primary somatosensory cortex (SI) hand area. All subjects showed additional deflections which peaked after 85 ms; the source locations agreed with the sites of the secondary somatosensory cortices (SII) in both hemispheres. The SII responses were typically stronger in the left than the right hemisphere. All subjects had an additional source, not previously reported in human evoked response data, in the contralateral parietal cortex. This source was posterior and medial to the SI hand area, and evidently in the wall of the postcentral sulcus. It was most active at 70–110 ms. 相似文献
75.
Mark J Elder MD FRACS FRACO Paul Hiscott PhD FRCS MRCPath John K.G Dart DM FRCS FRCOphth 《Human pathology》1997,28(12):1348-1354
Cicatricial conjunctivitis may be a sequel to systemic disorders (eg, Stevens-Johnson syndrome, cicatricial pemphigoid) or local disorders such as chemical burns. The cicatrisation is often associated with corneal epithelial changes that cause visual loss. These have been attributed to encroachment of the conjunctival epithelium over the cornea. However, the epithelial anomalies are poorly understood. We investigated the corneal epithelial changes in cicatricial conjunctivitis with an immunohistochemical study of intermediate filaments in normal and pathological specimens. Our results show that the normal corneal epithelium is immunoreactive for cytokeratin 3 (CK 3) but not cytokeratin 19 (CK 19), whereas normal conjunctival epithelium is CK 3 negative and CK 19 positive. Conjunctiva artificially transposed over the cornea (after therapeutic conjunctival flap reconstruction) retained the normal pattern of conjunctival cytokeratin expression (CK 3 negative, CK 19 positive). Conversely, the entire corneal epithelium exhibited the normal cytokeratin pattern (CK 3 positive, CK 19 negative) in 82% of Stevens-Johnson, 80% of cicatricial pemphigoid, and 69% of chemical burns specimens. The findings suggest that conjunctival encroachment is not responsible for the changes at the corneal surface in cicatricial conjunctivitis and that the abnormal corneal epithelium is derived from native corneal cells in these diseases. 相似文献
76.
Danka Peričié Hari Manev Sonja Levanat Branimi Jernej Dunja Vujić Nebojša Djordjević 《Psychopharmacology》1986,90(1):112-118
Acute (50.0 mg/kg) and repeated (0.1–10.0 mg/kg) administration of dihydroergosine (DHESN) to rats over 5 days lowered the concentration of 5-HIAA in the brain. DHESN given acutely increased the brain 5-HT in p-CPA-treated animals and diminished the probenecid-induced increase in brain 5-HIAA. In pargyline-treated rats DHESN enhanced the 5-HT/5-HIAA ratio. DHESN administered to rats repeatedly over 5 days decreased the level of 5-HT in blood platelets, and in vitro at concentrations of 10-4 M and 10-3 M inhibited the uptake of [14C]-5-HT in platelets. DHESN (10.0–100.0 mg/kg) potentiated the 5-HT syndrome produced in rats by pargyline and 5-HTP. This potentiation was blocked with cyproheptadine but not with haloperidol. DHESN (1.0 and 10.0 mg/kg) lowered the locomotor activity of rats and 10.0 mg/kg DHESN also reduced the duration of immobility in rats forced to swim in a restricted space. The results indicate that DHESN, like antidepressants, decreases the turnover of serotonin in the brain and potentiates the 5-HT-mediated behaviour. This might suggest that the drug should be further investigated for its potential antidepressive properties. 相似文献
77.
Gerard T. Williams FRCS Christopher J. Underwood B Sc David Charlesworth FRCS 《Annals of vascular surgery》1986,1(2):208-213
We report the early results of a series of 86 femoropopliteal bypass operations in which a 5 mm diameter thin wall polytetrafluoroethylene (Gore-Tex) prosthesis was used. Sixty-five bypasses were implanted in men and 21 in women. Thirty bypasses were done in conjunction with an aortic bifurcation graft and 18 patients had a bilateral procedure. The indication for operation was severe claudication in 74 cases and critical ischaemia in 12 cases. The angiographic run-off was good (three patent vessels) in 22 limbs and poor (one or two patent vessels) in 64 limbs. The cumulative patency rate for the whole group was 62% after 18 months. Angiographic run-off and the indication for operation were both found to influence cumulative patency rate significantly (p=0.035 and p=0.055, respectively). We also compared the results obtained when run-off was poor with equivalent data from our own previously published series in which a standard 6 mm diameter Gore-Tex prosthesis was used. This shows a difference in patency rate, for example 57% against 37% after 18 months, in favour of the smaller bore thin wall graft. 相似文献
78.
Analysis of the morphological aspects of continuous-wave Doppler examination is a reliable means of detecting carotid stenosis involving 50% or more of the diameter of the arterial lumen. This study was undertaken to evaluate the indexes likely to increase the diagnostic accuracy of this noninvasive investigation method. The indexes studied were the variations of the maximal frequency and the systolic peak frequencies, measured proximal to and at the level of stenosis, and the ratio of the systolic peak frequency measured in the internal carotid artery and in the common carotid artery. After obtaining data on an experimental model, the study was conducted in healthy volunteers (n = 24) and in patients with carotid atherosclerotic disease (n = 23). The experimental study confirmed that stenosis greater than 50% leads to a reduction of blood flow and that there is a mathematical relationship between the frequency measured proximal to and at the level of the stenosis and the degree of stenosis. Clinical data showed that there was a significant decrease in the frequency of the systolic peak in elderly "healthy" subjects as compared with younger subjects. However there was no difference between patients with and without stenosis. The index was 0.8 in young subjects, 1.3 in healthy elderly subjects, and greater than 1.3 in subjects who had a stenosis. There was no statistically significant difference between these two last groups. At the threshold value of 2.3, the sensitivity of the FI index was 22% and the specificity was 94% in the detection of carotid artery stenosis. In the assessment of the tight stenosis, sensitivity was 44%. 相似文献
79.
Matthew S. Austin Blair S. Ashley Nicholas A. Bedard Hari P. Bezwada Charles P. Hannon Yale A. Fillingham Yogesh V. Kolwadkar Harold W. Rees Matthew J. Grosso Erik N. Zeegen 《The Journal of arthroplasty》2021,36(8):2665-2673.e8
BackgroundThe prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.MethodsThe references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.Results282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.ConclusionMost of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration. 相似文献
80.