全文获取类型
收费全文 | 3309篇 |
免费 | 184篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 48篇 |
妇产科学 | 34篇 |
基础医学 | 418篇 |
口腔科学 | 57篇 |
临床医学 | 239篇 |
内科学 | 843篇 |
皮肤病学 | 130篇 |
神经病学 | 158篇 |
特种医学 | 183篇 |
外科学 | 498篇 |
综合类 | 14篇 |
预防医学 | 171篇 |
眼科学 | 90篇 |
药学 | 170篇 |
中国医学 | 5篇 |
肿瘤学 | 373篇 |
出版年
2022年 | 39篇 |
2021年 | 63篇 |
2020年 | 33篇 |
2019年 | 50篇 |
2018年 | 68篇 |
2017年 | 49篇 |
2016年 | 64篇 |
2015年 | 49篇 |
2014年 | 91篇 |
2013年 | 97篇 |
2012年 | 140篇 |
2011年 | 134篇 |
2010年 | 75篇 |
2009年 | 69篇 |
2008年 | 132篇 |
2007年 | 143篇 |
2006年 | 128篇 |
2005年 | 131篇 |
2004年 | 118篇 |
2003年 | 147篇 |
2002年 | 148篇 |
2001年 | 111篇 |
2000年 | 132篇 |
1999年 | 94篇 |
1998年 | 40篇 |
1997年 | 43篇 |
1996年 | 27篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 77篇 |
1991年 | 77篇 |
1990年 | 79篇 |
1989年 | 63篇 |
1988年 | 66篇 |
1987年 | 50篇 |
1986年 | 53篇 |
1985年 | 43篇 |
1984年 | 39篇 |
1983年 | 41篇 |
1982年 | 27篇 |
1981年 | 22篇 |
1979年 | 31篇 |
1977年 | 23篇 |
1974年 | 36篇 |
1973年 | 30篇 |
1972年 | 23篇 |
1971年 | 34篇 |
1970年 | 34篇 |
1969年 | 28篇 |
1968年 | 22篇 |
排序方式: 共有3505条查询结果,搜索用时 15 毫秒
1.
Shinji Naganawa Rintaro Ito Hisashi Kawai Toshiaki Taoka Tadao Yoshida Michihiko Sone 《Magnetic resonance in medical sciences》2020,19(4):375
Purpose:It has been reported previously that intravenously administered gadolinium-based contrast agent (GBCA) leaks into the subarachnoid space around the cortical veins at 4 h after injection in all old people over 37 years, but not in younger people up to 37 years of age in 3D-real IR images. The purpose of this study was to investigate whether there was a strict threshold of 37 years of age for the leakage of the GBCA into the subarachnoid space.Methods:The subjects included 190 patients, that were scanned for 3D-real IR images at 4 hours after intravenous injection of GBCA as a diagnostic test for endolymphatic hydrops. The patient’s age ranged from 14 to 81 years. Two experienced neuroradiologists evaluated the images to determine whether the GBCA leakage around the cortical veins was positive or negative. Any discrepancies between the two observers were discussed and a consensus was obtained.A Mann–Whitney U test and receiver operating characteristic (ROC) curve analysis were used to compare the positive and the negative group and to set the age cut-off value for the prediction of GBCA leakage.Results:The GBCA leakage around the cortical veins was negative in 35 patients and positive in 155 patients. The average age was 33 ± 11 years in the negative group, and 55 ± 12 years in the positive group (P < 0.01). In the ROC analysis for the age and leakage of the GBCA, an area under the curve was 0.905 and the cut-off age was 37.317 years (sensitivity of 0.942 and specificity of 0.771).Conclusion:Intravenously administered GBCA leaks into the subarachnoid space around the cortical veins in most patients over 37 years of age. However, it should be noted that it can be found occasionally in patients under 37 years of age. 相似文献
2.
Neurotoxic effects of flunarizine (Fz), a selective calcium channel blocker, on the nigrostriatal dopamine system was investigated. Systemic injections of Fz to mice resulted in a transient loss of tyrosine hydroxylase (TH) immunoreactive nigrostriatal neurons without cell loss. TH immunoreactivity in these neurons was greatly reduced as rapidly as one day after drug administration (regardless of dosage used) and thereafter recovered in both dose- and time-dependent manners. Such a novel neurotoxic action of Fz may constitute a morphological substrate for reversible drug-induced parkinsonian signs described in recent clinical case reports. 相似文献
3.
H Hirai K Yamasaki H Kidena M Kono 《Kaku igaku. The Japanese journal of nuclear medicine》1992,29(12):1447-1454
In vivo sodium concentrations in the normal brain tissue and a tumorous tissue were analyzed using MR Na image. The nuclear magnetic resonance enabled us to divide the signal from sodium in the living tissue into 2 parts based on the differences of T2 value. Those are fast component having the T2 value of less than 5 msec and slow component of 15-40 msec. We investigated the effect of macromolecules on T2 value of sodium image using polyvinyl alcohol (PVA) powder. MR Na image was taken with the parameters of TR/TD, 110 ms/1.9 ms (FID image) and TR/TE, 110 ms/20 ms (SE image). Saline solution showed high intensity on both FID image and SE image. Saline solution added PVA (PVA phantom) also showed high intensity on FID image, whereas the signal intensity of PVA phantom in SE image extinguished. To know the relation between the signal intensity and sodium concentration, sodium concentration--signal intensity curve was obtained using phantoms with various sodium concentrations (0.05-1.0%). This curve showed a direct proportion between sodium concentration and signal intensity on Na image. We measured further the sodium concentrations of the human brain tissue. Sodium phantoms were arranged around the heads and the MR Na images of the normal brains from 3 volunteers and a patient with a brain tumor (meningioma) were taken. The sodium concentrations of occipital lobe, basal ganglia and the tumorous tissue were calculated using the sodium concentration--signal intensity curve obtained from the phantoms arranged around the heads.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
Calcium cycling proteins of the cardiac sarcoplasmic reticulum. 总被引:2,自引:0,他引:2
Michihiko Tada 《Circulation journal》2003,67(9):729-737
5.
The purpose of this study was to determine the effect of pulsatile flow on cerebral perfusion under cardiopulmonary bypass (CPB). Twenty-three patients who underwent cardiac operations were divided into two comparable groups: Group A (N = 11) had standard nonpulsatile flow, while in Group B (N = 12), a pulsatile pump was used. The blood flow of left common carotid artery and radial arterial pressure were continuously monitored during cardiac operation in both groups and cerebral vascular resistance was calculated. In Group B, the perfusion pressure of left common carotid artery was monitored and compared with that of radial artery. Arterial and internal jugular venous blood were sampled and the difference of cerebral A.V O2 contents and cerebral oxygen consumption was calculated. Cerebral vascular resistance in Group B (54.0 +/- 11.2% of the value of before-CPB) significantly decreased compared to that in Group A (72.2 +/- 11%) at the end of CPB (p less than 0.05). Pulse pressure following pulsatile CPB flow was 15.1 +/- 5.8 mmHg monitored in radial artery and it reduced to 8.5 +/- 5 mmHg in left common carotid artery. Although there was no significant difference in cerebral oxygen consumption of both groups during and just after CPB, the difference of cerebral A-V O2 contents of Group B was greater than Group A just after CPB. These data suggest that pulsatile flow may minimize the cerebral microcirculatory shunt during CPB, resulting from the reduction of cerebral vascular resistance. 相似文献
6.
7.
Michihiko Fukui Maho Imoto Nobuaki Shime Tetsuo Hatanaka Hideaki Tojo 《Journal of anesthesia》1997,11(1):27-31
We developed a continuous oxygen consumption (Vo2) measurement system employed the reversed Fick method, in which Vo2 in computed from continuously measured sured arterial and mixed venous oxygen saturation assed by pulse oximetry and mixed
venous oximetry, respectively, and cardiac output by the heat deprivation technique. This system was compared with the conventional
intermittent reversed fick method in 7 patients during surgery and with indirect calorimetry in 4 intensive care unit (ICU)
patients. The Vo2 measured by the continuous reversed Fick method showed a high correlation with those simultaneously measured by the intermittent
Fick method (r=0.97,P<0.01) and by indirect calorimetry (r=0.74,P<0.01). The 95% confidence limits (bias±2 SD) of the continuous reversed Fick method were −0.6±45 ml·min−1 with the intermittent Fick method and −31±56 ml·min−1 with indirect calorimetry. The continuous Fick method is in satisfactory agreement with the conventional methods for the
measured of Vo2 and potentially allows for convenient assessment of Vo2 in critically ill patients.
This study was supported in part by Grants-in-Aid for the Encouragement of Young Scientists 01771185 and 04857171 from the
Ministry of Education, Science and Culture of Japan 相似文献
8.
Differential expression of the beta I- and beta II-PKC subspecies in the postnatal developing rat brain; an immunocytochemical study. 总被引:1,自引:0,他引:1
Differential expression of protein kinase C subspecies, beta I- and beta II-PKC, derived from a single gene by alternative splicing was evidenced in the postnatal developing rat brain. Immunoblot analysis of the PKC subspecies in the whole developing brain showed that beta I-PKC was present at birth and then gradually increased, while beta II-PKC was not present at birth or on postnatal day 3, then increased rapidly from day 7 to the maximum value seen in the adult brain. Under light microscopy, beta I-PKC immunoreactivities seen at birth were the most intense in the brainstem and intense in the diagonal bundle and globus pallidus. beta I-PKC immunoreactivities in these neurons weakened from day 7 and disappeared in the adult brain, while in the cerebral cortex, triangular septal nucleus and pontine nucleus beta I-PKC immunoreactivities were week at birth and then gradually increased. beta II-PKC immunoreactivities were first visible in neurons on day 7 and increased progressively. beta I- and beta II-PKCs were not co-localized in a neuron, as far as examined. The immunoreactivities of beta I-PKC at birth were localized in growth cone-like structures as well as in the dendrites and perikarya. Similarly, alpha-PKC was also present at birth in the growth cone-like structure. Immunoblot analysis revealed that beta I-PKC was present at birth in the growth cone-rich fraction from the hindbrain but not in that from the forebrain, while alpha-PKC was found in the growth cone-rich fraction from both the forebrain and the hindbrain. beta II- and gamma-PKC were not detected in the growth cone-rich fraction from either forebrain or hindbrain. These findings suggest that beta I- and beta II-PKC play a role in different stages of development and in different neurons; both beta-subspecies may be involved in postnatal developing neuronal functions while only beta I-PKC plays functional roles in the growth cone, in the prenatal developmental stage. 相似文献
9.
10.
Risk of gallstones following gastrectomy in Japanese men 总被引:3,自引:0,他引:3
Yoichi Ikeda Koichi Shinchi Suminori Kono Kenji Tsuboi Keizo Sugimachi 《Surgery today》1995,25(6):515-518
The risk of gallstones developing after gastrectomy in middle-aged Japanese men was investigated in a study of 2,738 men aged between 48 and 56 years who underwent both gallbladder ultrasonography (US) and a barium study of the upper digestive tract. It was revealed that 61 men had gallstones, 37 had had their gallbladder removed previously, and 55 had a history of gastrectomy. The prevalence of gallstones was 3.5 times higher in the men who had previously undergone gastrectomy (7.7%) than in those who had not (2.2%) (P=0.03). Moreover, gallstones tended to be more prevalent in those who had undergone Billroth II gastrectomy (12.5%) compared with those who had undergone Billroth I gastrectomy (5.6%); however, the difference was not significant. These results indicate that gastrectomy using either Billroth I or Billroth II reconstruction predisposes to gallstone formation. Nevertheless, it was estimated that prior gastrectomy was responsible for no more than 5% of gallstones in the study population. 相似文献