全文获取类型
收费全文 | 33065篇 |
免费 | 1677篇 |
国内免费 | 202篇 |
专业分类
耳鼻咽喉 | 390篇 |
儿科学 | 569篇 |
妇产科学 | 329篇 |
基础医学 | 4221篇 |
口腔科学 | 902篇 |
临床医学 | 2372篇 |
内科学 | 8318篇 |
皮肤病学 | 568篇 |
神经病学 | 2487篇 |
特种医学 | 1306篇 |
外科学 | 5275篇 |
综合类 | 193篇 |
预防医学 | 1191篇 |
眼科学 | 474篇 |
药学 | 2817篇 |
中国医学 | 72篇 |
肿瘤学 | 3460篇 |
出版年
2022年 | 272篇 |
2021年 | 605篇 |
2020年 | 281篇 |
2019年 | 426篇 |
2018年 | 552篇 |
2017年 | 443篇 |
2016年 | 538篇 |
2015年 | 565篇 |
2014年 | 769篇 |
2013年 | 954篇 |
2012年 | 1406篇 |
2011年 | 1493篇 |
2010年 | 880篇 |
2009年 | 767篇 |
2008年 | 1324篇 |
2007年 | 1367篇 |
2006年 | 1428篇 |
2005年 | 1521篇 |
2004年 | 1428篇 |
2003年 | 1410篇 |
2002年 | 1442篇 |
2001年 | 1235篇 |
2000年 | 1373篇 |
1999年 | 1200篇 |
1998年 | 428篇 |
1997年 | 326篇 |
1996年 | 331篇 |
1995年 | 275篇 |
1994年 | 263篇 |
1993年 | 258篇 |
1992年 | 807篇 |
1991年 | 721篇 |
1990年 | 734篇 |
1989年 | 778篇 |
1988年 | 710篇 |
1987年 | 637篇 |
1986年 | 608篇 |
1985年 | 573篇 |
1984年 | 450篇 |
1983年 | 335篇 |
1982年 | 193篇 |
1981年 | 152篇 |
1980年 | 161篇 |
1979年 | 284篇 |
1978年 | 225篇 |
1977年 | 173篇 |
1974年 | 165篇 |
1973年 | 152篇 |
1971年 | 154篇 |
1969年 | 171篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
71.
Kazuo Yamakawa Masashi Takanashi Masao Watanabe Noriyuki Nakamura Tomonori Kobayashi Masato Hasegawa Yoshikuni Mizuno Shigeki Tanaka Hideo Mori 《Neuropathology》2006,26(6):586-591
We report on a male patient with Pick disease who had shown severe white matter atrophy and dilatation of the lateral ventricle in the frontal lobe from an early stage. Upon admission to our hospital 2 years after disease onset, the patient showed apathy, and MRI revealed severe atrophy of the cortex and white matter of the frontal lobe. He died at age 74, 11 years after disease onset. Autopsy revealed severe atrophy of the frontal and temporal lobes, severe loss of white matter in the frontal lobe, dilatation of the lateral ventricles, and cortical thinning. Histopathological examination showed severe loss of myelinated fibers in the frontal white matter and severe neuronal loss with gliosis in the frontal and temporal cortices. Many Pick bodies were seen. Our patient had a rare case of Pick disease predominantly affecting the frontal lobe with severe involvement of the white matter from an early stage. This case suggests that myelinated fibers in the white matter as well as cerebral neurons are primarily affected in Pick disease. 相似文献
72.
Senichiro Kikuchi Kazuhiko Iwata Yasunori Onishi Fumio Kubota Koichi Nisijima Hideaki Tamai Yuiko Koizumi Eiju Watanabe Satoshi Kato 《Psychiatry Research: Neuroimaging》2007,156(3):199-208
We conducted a noninvasive near-infrared spectroscopy (NIRS) study using the game of rock, paper, scissors (RPS) as a simple neurocognitive task for the prefrontal cortex (PFC) in 15 healthy volunteers. We employed an opposite “to lose” RPS task coupled with a normal “to win” RPS task, since the former requires inhibition of behavior, one of the most important functions of the prefrontal cortex. During the NIRS examination, subjects had to present one of the three RPS hands in response to hands displayed randomly on a computer screen every 1.5 s, and were required to show hands that lose to the computer, or that beat the computer. We measured the relative concentrations of oxyhemoglobin (oxy-Hb) using the prefrontal probes of the NIRS system during the tasks. The increases in oxy-Hb during the “to win” RPS task were small, but were quite large and laterally dominant during the “to lose” RPS task. The difference between the two tasks might have been due to the participants’ cognitive conflict with losing on the RPS. We conclude that losing is better than winning on the RPS as a sensitive indicator in the NIRS examination of PFC. 相似文献
73.
Masato Miwa Mayumi Matsunaga Noriyuki Nakajima Shintaro Yamaguchi Kensuke Watanabe 《Otolaryngology--head and neck surgery》2007,136(1):62-66
OBJECTIVE: The effect of tonicity changes in nebulizer solutions and irrigations on nasal mucosa is not well known. The present study aims to determine the basic mechanism of hypertonic solution on airway epithelial barrier. STUDY DESIGN AND SETTING: We investigated the electrical potential difference (PD) that is influenced by both active transport and the transepithelial electrical resistance of the epithelial mucosa in the human nose in vivo. The short circuit current (SCC) revealed net ion transport across the epithelium in the guinea pig trachea in vitro. Finally, the size dependency of macromolecules across the tracheal mucosa was determined in vitro using FITC-labeled dextrans of different sizes. RESULTS: PD was significantly decreased after topical application of hypertonic solution both in human and in guinea pig nose. SCC was significantly decreased after application of hypertonic solution. The transport of these dextrans from the basolateral to the apical side was not increased significantly after apical application of hypertonic saline. CONCLUSIONS: Hypertonic saline enhances the electrical permeability of the airway epithelial mucosa but not transport of macromolecule in the short term. 相似文献
74.
We recorded neurons sensitive to depth movement from the inferior parietal lobule (area 7a) of alert behaving monkeys, and studied their response to changing sizes of retinal images and to changing binocular disparity. The size of the stimulus was changed by changing both the height and width of a slit in the same way, and the disparity change was produced by varying distances between a pair of polarized stimuli on a screen. Of 227 purely visual neurons recorded from 11 hemispheres of 7 monkeys, 32 neurons responded to the change of either the size or disparity, or both. Some of the neurons sensitive to size change could be activated by changing length on only one axis, but the optimal stimulus for most of them was a uniform change of size in all directions. The neurons sensitive to disparity change responded weakly to monocular stimuli, but showed clear selectivity in the direction of change of disparity when binocular stimuli were applied. We also found a group of depth movement sensitive neurons that responded maximally to the simultaneous change of size and disparity. This type of neurons may signal real depth movement by integrating the signals of size change and disparity change. 相似文献
75.
Y. Tani T. Ishihara T. Kanai T. Ohno J. Andersson A. Lilja G. Antoni K. -J. Fasth P. Bjurling G. Westerberg P. Hartvig H. Onoe Y. Watanabe B. Langström 《Journal of neural transmission (Vienna, Austria : 1996)》1995,102(3):189-208
Summary The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[11C]methyl-benztropine) and dopaminergic receptor ligands selective for D1 D2, and D3 subtypes ([11C]SCH23390, N-[11C]methyl-spiperone, and (+)[11C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H2
15O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [18F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[11C]methyl-benztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [11C]SCH23390 (dopamine D1 receptor) binding. However, the k3 value for N-[11C]methyl-spiperone (dopamine D2 receptor) binding, which represents the association rate × Bmax value, was significantly decreased in the striatum. The uptake ratio of (+)[11C]UH232 (dopamine D3 receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D2 and D3 receptors selectively without markedly affecting dopamine D1 receptor binding. Furthermore, the changes in cholinergic and dopamine D2 and D3 receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.Abbreviations
R-THBP
6R-L-erythro-5,6,7,8-tetrahydrobiopterin
-
PET
positron emission tomography
-
rCBF
regional cerebral blood flow
-
rCMRglc
regional cerebral metabolic rate of glucose 相似文献
76.
Hiroaki Yuasa Koji Kawanishi Jun Watanabe 《The Journal of pharmacy and pharmacology》1995,47(7):576-580
The effects of ageing on the oral (gastrointestinal) absorption of d -xylose were investigated by analysing the gastrointestinal disposition after oral administration to young (9 weeks) and old (53 weeks) rats. A linear model assuming first-order gastric emptying followed by first-order intestinal absorption was fitted to remaining fraction vs time profiles for the stomach and small intestine to estimate the gastric emptying rate constant (kg) and the intestinal absorption rate constant (ka). In young and old rats, kg values were 0·087 ± 0·008 and 0·070 ± 0·007 min?1, respectively, and ka values were 0·020 ± 0·002 and 0·018 ± 0·002 min?1 suggesting an insignificant effect on ageing on the rate of oral absorption. The average intestinal lumen volume (Vav) was unchanged with ageing, and so was the apparent intestinal membrane permeability clearance (CLapp) as the product of ka and Vav. However, the small intestinal transit time (Tsi) was suggested to be twice that in older rats (171 min) than in young rats (78 min) by the analysis of gastrointestinal disposition of inulin, a non-absorbable marker. It was also shown that our preceding finding of an increase in the fraction absorbed of D-xylose with ageing can be solely ascribable to the delay in intestinal transit. Thus, among various determinants of oral absorption, only Tsi was found to be altered with ageing. The CLa,app and ka of passively absorbed drugs such as D-xylose may be generally unchanged, and the fraction absorbed may increase with ageing by the delay in intestinal transit. 相似文献
77.
Kazuhiko Kyoshima Susumu Oikawa Miki Kanaji Hideo Zenisaka Takeomi Takizawa Tetsuya Goto Hisayoshi Takasawa Atsushi Watanabe Kazuo Tokushige Keiichi Sakai 《Journal of clinical neuroscience》2003,10(5):571-578
Some chordomas have a very poor prognosis because of their aggressive growth nature, but the efficacy of repeat operations for these cases has not been well documented. This report concerns 3 patients with aggressive chordoma of the clivus, who underwent operations 6 to 12 times over a period of 8 to 17 years because of symptomatic regrowth. Overall mean interval between repeat operations was 18 months with a range from 5 to 57 months and survival times were 9 to19 years after the first surgery. Main symptoms before each operation were diplopia and visual disturbance. Repeat palliative operations by intentional extradural debulking of the tumour to decompress offending neural structures, as well as maximal removal of the tumour, using appropriate skull base approaches, can mitigate progressive symptoms, and may result in better quality and some prolongation of life, although our patients gradually deteriorated neurologically throughout the clinical course. 相似文献
78.
MRI of ossification of ligamentum flavum. 总被引:11,自引:0,他引:11
H Sugimura Y Kakitsubata Y Suzuki S Kakitsubata S Tamura O Uwada T Kodama T Yano K Watanabe 《Journal of computer assisted tomography》1992,16(1):73-76
Magnetic resonance imaging of 28 patients with radiological and/or histopathologically proved ossification of the ligamentum flavum (OLF) was reviewed. The locations of OLF were cervical (n = 4), thoracic (n = 22), and lumbar (n = 2). On T1- and T2-weighted images, OLF demonstrated low signal intensity. Areas of high or intermediate signal intensity within the OLF on T1-weighted images were observed in three cases and were interpreted to be due to fat infiltration. In six cases, high intensity areas in the spinal cord caused by compressing OLF were demonstrated on T2-weighted images. Gadolinium-diethylenetriamine pentaacetic acid, which was used in four cases, showed cord enhancement at the level of compression by OLF in three cases. 相似文献
79.
M Yamagishi H Koba A Honma A Nakagawa K Yokokawa K Kurokawa T Saito Y Mori H Watanabe S Katoh 《Nihon Kyōbu Shikkan Gakkai zasshi》1991,29(11):1407-1413
We analyzed the CT images (in vivo) of 5 lobes (right middle lobe, 1; left lower lobe, 1; right lower lobe, 3) with panacinar emphysema (PAE) obtained at autopsy or thoracotomy for solitary lung tumor. The lobes were inflation-fixed by the method of Heitzman and sliced axially for a CT-pathologic correlative study. One lobe with mild PAE had normal appearance on CT; however, the other four lobes with PAE demonstrated low-attenuation areas (LAAs) of various shapes and sizes on CT. LAAs were locally distributed on CT slices in one lobe, dominant in the inner zones in two lobes, and diffuse in one lobe. Relatively normal to diminished vasculature was observed within the LAAs of four lobes. These CT findings differed significantly from those of centriacinar emphysema (CAE) as reported in other studies. We conclude that CT is useful in the clinical diagnosis of PAE and its differentiation from CAE. 相似文献
80.
Summary A case of hemodialysis-associated amyloidosis in a patient who had been on hemodialysis for 10 years is described. Bone lesions were found in the humeral heads, carpal bones, and femoral heads and necks. Specimens obtained from the pathologically fractured left femoral neck revealed amyloid deposits histologically. Immunoperoxidase staining for beta-2 microglobulin was positive in the amyloid at the light-microscopic level. We reconfirmed that bone lesions associated with long-term hemodialysis are manifestations of amyloidosis of beta-2 microglobulin origin. Hemodialysis-associated amyloidosis should be considered in the treatment of long-term hemodialysis patients. 相似文献