全文获取类型
收费全文 | 7324篇 |
免费 | 390篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 156篇 |
儿科学 | 163篇 |
妇产科学 | 141篇 |
基础医学 | 964篇 |
口腔科学 | 295篇 |
临床医学 | 551篇 |
内科学 | 2133篇 |
皮肤病学 | 202篇 |
神经病学 | 413篇 |
特种医学 | 168篇 |
外科学 | 961篇 |
综合类 | 37篇 |
预防医学 | 222篇 |
眼科学 | 87篇 |
药学 | 514篇 |
中国医学 | 15篇 |
肿瘤学 | 745篇 |
出版年
2023年 | 65篇 |
2022年 | 132篇 |
2021年 | 199篇 |
2020年 | 100篇 |
2019年 | 126篇 |
2018年 | 167篇 |
2017年 | 132篇 |
2016年 | 140篇 |
2015年 | 145篇 |
2014年 | 174篇 |
2013年 | 249篇 |
2012年 | 455篇 |
2011年 | 425篇 |
2010年 | 252篇 |
2009年 | 217篇 |
2008年 | 399篇 |
2007年 | 363篇 |
2006年 | 355篇 |
2005年 | 382篇 |
2004年 | 342篇 |
2003年 | 326篇 |
2002年 | 378篇 |
2001年 | 182篇 |
2000年 | 187篇 |
1999年 | 189篇 |
1998年 | 90篇 |
1997年 | 87篇 |
1996年 | 72篇 |
1995年 | 63篇 |
1994年 | 48篇 |
1993年 | 48篇 |
1992年 | 113篇 |
1991年 | 88篇 |
1990年 | 92篇 |
1989年 | 109篇 |
1988年 | 99篇 |
1987年 | 107篇 |
1986年 | 94篇 |
1985年 | 73篇 |
1984年 | 59篇 |
1983年 | 51篇 |
1979年 | 50篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1974年 | 30篇 |
1973年 | 19篇 |
1972年 | 20篇 |
1970年 | 19篇 |
1968年 | 19篇 |
1966年 | 24篇 |
排序方式: 共有7767条查询结果,搜索用时 15 毫秒
11.
12.
Kazuo Okura Takafumi Kato Jacques Y Montplaisir Barry J Sessle Gilles J Lavigne 《Clinical neurophysiology》2006,117(2):269-278
OBJECTIVE: The aim of this study was to make a quantitative analysis of the changes in cranial and limb muscle activity from wakefulness to light and deep sleep stages and during rapid eye movement (REM) sleep of normal subjects. METHODS: Polysomnographic recordings were made of the sleep of 9 healthy human subjects, including electromyograms of the suprahyoid, temporalis and masseter cranial muscles and the anterior tibialis limb muscle. Quantitative assessments of EMG activity were carried out with root mean square (RMS) and frequency-spectral analysis (FSA) methods. RESULTS: From wakefulness to sleep, a significant reduction (-25.2 to -71.2%; P < 0.01) was observed in EMG activity (for both RMS and FSA) of the 3 cranial muscles using both methods of analysis. The EMG activity of suprahyoid muscle further decreased from non-REM to REM sleep (-17.8 to -43.0%; P < 0.01). In contrast, the EMG activity of the anterior tibialis muscle was only slightly reduced across sleep stages and did not further reduce during REM sleep. During REM sleep, all the 4 muscles maintained minimal activity. CONCLUSIONS: The maintenance of muscle activity during REM sleep suggests that a minimal level of activity is required to preserve physiological functions (e.g. airway patency, posture) related to homeostasis and bodily protection. SIGNIFICANCE: This study suggests that quantitative sleep EMG analysis is important for understanding the mechanisms of sleep-related movement disorders or when objective assessment of changes in EMG activity are needed for diagnostic purposes or for the assessment of drug efficiency. 相似文献
13.
We examined the absorptive capacity and the nutritional condition of 14 infants with short bowel syndrome, whose residual small intestine was 90 cm or less. Their age ranged from 1 year to 18 years. Examined items were body weight, height, serum albumin, total cholesterol, triglyceride, fat soluble vitamins, trace elements and rapid turn over protein as markers of the nutritional condition. Fecal fat, fecal bile acid, d-xylose absorption test, sugar-, amino acid-evoked potential difference in the small intestine and disaccharidase activity of the mucosa were examined as markers of the absorptive capacity. Our results showed that the body weight was below the normal range in the patients with small intestine of less than 50 cm. Most nutritional markers were within normal range, however, cholesterol and vitamin D were low in the patients with fat malabsorption, especially in patients with less than 50 cm of small intestine. Fecal bile acid was higher than the normal range in all the patients. Potential difference was in normal range or slightly lower than normal in all the patients. We concluded that infants with less than 50 cm of small intestine had malabsorption of sugar, protein and fat. Therefore, prolonged nutrient support, especially fat, is necessary. 相似文献
14.
Maroun Dick M.D. Tulio E. Bertorini M.D. Masanori Igarashi M.D. 《Developmental medicine and child neurology》1992,34(3):262-265
Respiratory failure is an unusual initial manifestation of congenital muscular dystrophy. The authors describe a case of congenital muscular dystrophy in a patient presenting with rhabdomyolysis at birth. Despite an initially poor prognosis, aggressive respiratory therapy during the neonatal period permitted normal subsequent development. The muscular dystrophy predominantly involved the respiratory muscles. 相似文献
15.
16.
Takashi Yamauchi Takafumi Masai Koji Takeda Satoshi Kainuma Yoshiki Sawa Kazuo Abe 《Annals of thoracic and cardiovascular surgery》2007,13(6):410-412
We report a rare case of constrictive pericarditis that stimulated a large mediastinal tumor obstructing the right ventricular inflow tract. A 58-year-old woman was referred to our hospital because of a recent increase of dyspnea and facial edema. Computed tomography revealed severely thickened calcification, including a low-density area, presenting as a mediastinal tumor, compressing the right ventricular inflow tract. A complete resection was performed, and her symptoms dramatically improved. Idiopathic constrictive pericarditis was diagnosed pathologically. 相似文献
17.
Takafumi Nagaoka Yoichi Katayama Toshikazu Kano Kazutaka Kobayashi Hideki Oshima Chikashi Fukaya Takamitsu Yamamoto 《Neuromodulation》2007,10(3):206-215
Objective. Employing [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to assess the correlation between the effect of deep brain stimulation (DBS) on the subthalamic nucleus (STN) and the regional cerebral metabolic rate of glucose (rCMRGlc) in advanced Parkinson's disease patients (N = 8). Materials and Methods. On the basis of patients’ diary records, we performed FDG‐PET during the off‐period of motor activity with on‐ or off‐stimulation by STN‐DBS on separate days and analyzed the correlation between changes in motor symptoms and alterations in the rCMRGlc. Result. When FDG‐PET was performed, the motor score on the unified Parkinson's disease rating scale (UPDRS) was 64% lower with on‐stimulation than with off‐stimulation (p < 0.001, Wilcoxon single‐rank test). STN‐DBS increased the rCMRGlc in the posterior part of the right middle frontal gyrus, which corresponded to the premotor area, and the right anterior lobe of the cerebellum (p < 0.005, paired t‐test). No region exhibited a decrease in rCMRGlc. Among the items of the UPDRS motor score, the changes in resting tremor and rigidity of the left extremities showed a significant correlation with the changes in rCMRGlc observed in the right premotor area (p < 0.02 and p < 0.05, respectively, Spearman's rank correlation). Conclusions. STN‐DBS either activates the premotor area or normalizes the deactivation of the premotor area. These FDG‐PET findings obtained are consistent with the idea that STN‐DBS modifies the activities of neural circuits involved in motor control. 相似文献
18.
Antimetastatic Activity of Polymeric RGDT Peptides Conjugated with Poly(ethylene glycol) 总被引:1,自引:0,他引:1
Ikuo Saiki Junya Yoneda Yu Igarashi Miho Aoki Naoto Kusunose Kei-ichi Ono Ichiro Azuma 《Cancer science》1993,84(5):558-565
Polymeric peptides containing defined repetitive or cyclic structures of RGDT sequence, (RGDT)n (n = 1 to 11) and cyclo(RGDT)n (n=2 to 4), at a dose of 500 μg exhibited an inhibitory effect on experimental lung metastasis upon co-injection with tumor cells and the magnitude of the effect increased in parallel with the increase of degree of repetition of the RGDT sequence. The conjugation of (RGDT)n (n = 1, 5, 11) with poly(ethylene glycol), PEG as a polymeric carrier led to enhanced inhibition of lung metastasis in proportion to the degree of RGDT sequence repetition and in a dose-dependent manner. Multiple i.v. administrations of PEG-(RGDT)11, at 2-day and 3-day intervals before the excision of primary tumors, effectively inhibited spontaneous lung metastasis by s.c. inoculation of tumors, whereas (RGDT)11 exhibited inhibition of lung metastasis only when given at 2-day intervals. This indicates that the conjugation of PEG with (RGDT)n allowed the prolongation of administration interval, implying a sustained inhibitory effect on tumor metastasis. In support of this supposition, a decrease in the arrest of radiolabeled tumor cells in the lungs was observed when PEG-(RGDT)11 was co-injected i.v. with tumor cells, or injected i.v. one day before tumor inoculation. In contrast, (RGDT)11 significantly inhibited the tumor cell arrest in the lungs only upon co-injection with tumor cells. We also noted that (RGDT)n, cyclo(RGDT)n and PEG-(RGDT)11 inhibited tumor cell invasion into Matrigel in a concentration-dependent manner and in proportion to the degree of RGDT sequence repetition, indicating that the peptide-mediated antimetastatic effect is partly associated with the anti-invasive potential. Thus, the conjugation of anti-cell adhesive and antimetastatic RGDT peptide with PEG might provide a therapeutically promising basis for the prevention of cancer metastasis (“anti adhesion therapy”). 相似文献
19.
Songji Zhao Yuji Kuge Takafumi Mochizuki Toshiyuki Takahashi Kunihiro Nakada Masayuki Sato Toshiki Takei Nagara Tamaki 《Journal of nuclear medicine》2005,46(4):675-682
The biologic mechanisms involved in the intratumoral heterogeneous distribution of 18F-FDG have not been fully investigated. To clarify factors inducing heterogeneous 18F-FDG distribution, we determined the intratumoral distribution of 18F-FDG by autoradiography (ARG) and compared it with the regional expression levels of glucose transporters Glut-1 and Glut-3 and hexokinase-II (HK-II) in a rat model of malignant tumor. METHODS: Rats were inoculated with allogenic hepatoma cells (KDH-8) into the left calf muscle (n = 7). Tumor tissues were excised 1 h after the intravenous injection of 18F-FDG and sectioned to obtain 2 adjacent slices for ARG and histochemical studies. The regions of interest (ROIs) were placed on ARG images to cover mainly the central (CT) and peripheral (PT) regions of viable tumor tissues and necrotic/apoptotic (NA) regions. The radioactivity in each ROI was analyzed quantitatively using a computerized imaging analysis system. The expression levels of Glut-1, Glut-3, and HK-II were determined by immunostaining and semiquantitative evaluation. The hypoxia-inducible factor 1 (HIF-1) was also immunostained. RESULTS: ARG images showed that intratumoral 18F-FDG distribution was heterogeneous. The accumulation of 18F-FDG in the CT region was the highest, which was 1.6 and 2.3 times higher than those in the PT and NA regions, respectively (P < 0.001). The expression levels of Glut-1, Glut-3, and HK-II were markedly higher in the CT region (P < 0.001) compared with those in the PT region. The intratumoral distribution of 18F-FDG significantly correlated with the expression levels of Glut-1, Glut-3, and HK-II (r = 0.923, P < 0.001 for Glut-1; r = 0.829, P < 0.001 for Glut-3; and r = 0.764, P < 0.01 for HK-II). The positive staining of HIF-1 was observed in the CT region. CONCLUSION: These results demonstrate that intratumoral 18F-FDG distribution corresponds well to the expression levels of Glut-1, Glut-3, and HK-II. The elevated expression levels of Glut-1, Glut-3, and HK-II, induced by hypoxia (HIF-1), may be contributing factors to the higher 18F-FDG accumulation in the CT region. 相似文献
20.
The three-dimensional relationship between the acetabulum and femoral head was evaluated using three-dimensional computed tomography (CT) reconstruction before and after rotational acetabular osteotomy. This method provides exact anatomic information on acetabular coverage so that precise operative planning is more easily made. Evaluation of six dysplastic hips indicated the possible dangers of anterolateral rotational shift of the acetabulum when there is marked posterior deficiency, such as in the case of a high decree of subluxated femoral head covered by a shallow false acetabulum. In these circumstances, it may be safer and preferable to plan a lateral shift instead of an anterolateral shift. 相似文献