全文获取类型
收费全文 | 6817篇 |
免费 | 273篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 116篇 |
妇产科学 | 107篇 |
基础医学 | 939篇 |
口腔科学 | 97篇 |
临床医学 | 382篇 |
内科学 | 1723篇 |
皮肤病学 | 74篇 |
神经病学 | 521篇 |
特种医学 | 235篇 |
外科学 | 1349篇 |
综合类 | 26篇 |
一般理论 | 1篇 |
预防医学 | 171篇 |
眼科学 | 215篇 |
药学 | 364篇 |
中国医学 | 8篇 |
肿瘤学 | 766篇 |
出版年
2023年 | 33篇 |
2022年 | 54篇 |
2021年 | 153篇 |
2020年 | 72篇 |
2019年 | 89篇 |
2018年 | 110篇 |
2017年 | 88篇 |
2016年 | 131篇 |
2015年 | 129篇 |
2014年 | 189篇 |
2013年 | 237篇 |
2012年 | 385篇 |
2011年 | 392篇 |
2010年 | 206篇 |
2009年 | 188篇 |
2008年 | 365篇 |
2007年 | 391篇 |
2006年 | 338篇 |
2005年 | 390篇 |
2004年 | 417篇 |
2003年 | 388篇 |
2002年 | 371篇 |
2001年 | 149篇 |
2000年 | 129篇 |
1999年 | 146篇 |
1998年 | 78篇 |
1997年 | 91篇 |
1996年 | 69篇 |
1995年 | 72篇 |
1994年 | 69篇 |
1993年 | 69篇 |
1992年 | 86篇 |
1991年 | 92篇 |
1990年 | 78篇 |
1989年 | 99篇 |
1988年 | 96篇 |
1987年 | 62篇 |
1986年 | 67篇 |
1985年 | 65篇 |
1984年 | 47篇 |
1983年 | 45篇 |
1982年 | 31篇 |
1981年 | 31篇 |
1980年 | 27篇 |
1979年 | 34篇 |
1978年 | 27篇 |
1976年 | 24篇 |
1974年 | 22篇 |
1972年 | 22篇 |
1971年 | 23篇 |
排序方式: 共有7129条查询结果,搜索用时 31 毫秒
91.
Nobushige Yamashita Shiro Hoshida Kinya Otsu Naoyuki Taniguchi Tsunehiko Kuzuya Masatsugu Hori 《British journal of pharmacology》1999,128(2):412-418
1 We utilized a rat model of myocardial infarction to investigate whether cardioprotection by monophosphoryl lipid A (MLA) is provided in the early and late phases, as well as to determine whether this cardioprotection may be related to the activation of manganese superoxide dismutase (Mn-SOD), an intrinsic radical scavenger. 2 Pretreatment with MLA (0.5 or 1.0 mg kg-1, i.v.) 24 h prior to 20-min left coronary artery (LCA) occlusion and 48-h reperfusion significantly decreased the incidence of ventricular fibrillation (VF) during ischaemia, as well as infarct size. Pretreatment with lower concentrations of MLA, however, was ineffective. 3 When we examined the time course of MLA (0.5 mg kg-1)-induced cardioprotection, both infarct size and the incidence of VF were significantly reduced in rats pretreated with MLA 0.5 h and 24 h before occlusion. We observed no differences, however, 2 and 72 h after MLA treatment. 4 The activity of Mn-SOD paralleled the cardioprotective effects of MLA. Mn-SOD activity in the myocardium was significantly enhanced in rats pretreated with MLA (0.5 mg kg-1) 0.5 and 24 h before. Mn-SOD activity was not altered, however, in rats pretreated 2 or 72 h before. Lower MLA concentrations were not effective even 24 h after the treatment. 5 We conclude that MLA treatment induced a biphasic pattern of cardioprotection. The pattern of Mn-SOD activity suggests that this enzyme may play a major role in the acquisition of cardioprotection against ischaemia-reperfusion injury. 相似文献
92.
N Matsumoto T Tsuchida H Nakamura R Sawa Y Takahashi H Naganawa H Iinuma T Sawa T Takeuchi M Shiro 《The Journal of antibiotics》1999,52(3):276-280
The absolute structure of a new antibiotic lactonamycin is described. The NMR studies deduced one of four possible structures for the aglycon attached by a rhodinose through glycosidic bond. The stereochemistry of the sugar obtained by an acid hydrolysis was determined to be L-form by measuring optical rotation. The stereochemistry of the aglycon was determined by X-ray crystallographic analysis. 相似文献
93.
Hideki Horita M.D. Eiichi Hoashi M.D. Yuko Okuyama M.D. Koumei Kumagai M.D. Shiro Endo M.D. 《Psychiatry and clinical neurosciences》1977,31(3):393-402
We observed the attacks of nystagmus in a case of infantile spasms and carried out overnight sleep polygraphy. The following findings were obtained:
- 1 Awake time was prolonged to 56% of TIB, while sleep time was markedly shortened to 44% of TIB. Also REM sleep time was reduced to 20% of SPT and deep slow sleep (stage N3) was absent.
- 2 Attacks of nystagmus were observed only during wakefulness. At first, fast wave bursts appeared in the right occipital area, and were followed by left-upward deviations of eyeballs, and then the attacks of counterclockwise right-downward rotatory nystagmus. Also the fast wave bursts were succeeded by spreading of fast waves to adjacent areas. At the same time, EMG exhibited elevated muscle action potentials of mentalis and biceps fernoris. During the attacks of nystagmus, there was alteration of respiratory movements.
94.
H. Ozaki MD H. Sato M. Hori T. Matsuyama K. Imai H. Yokoyama A. Kitabatake M. Inoue T. Kamadal 《European journal of clinical pharmacology》1992,43(5):455-461
Summary Xamoterol acts as a
1-adrenoceptor agonist at low sympathetic activity and as an antagonist at high activity. Although its long-term efficacy has been proven in patients with mild to moderate heart failure, it remains unclear which effect, agonism or antagonism, accounts for its long-term activity.To clarify the effect of xamoterol on cardiac sympathetic activity in daily life, 24-h R-R interval histograms were obtained during administration of xamoterol 100 mg b. d. for 1 week to 10 patients with mild to moderate heart failure. Eight normal subjects were also studied as controls. To examine the relation between the effect of xamoterol and sympathetic activity, plasma noradrenaline (NA) levels were measured under 5 graded conditions simulating daily living.Xamoterol administration significantly decreased the standard deviation of the R-R interval, both in patients with heart failure and in normal subjects. The mean R-R interval, however, was increased in patients with heart failure, relative to normal subjects.In both groups, the R-R interval histograms had two peaks, i. e. a short daytime peak and a long night-time peak. Xamoterol decreased the median of the night-time peak without changing the daytime peak in normal subjects. In contrast, it increased the median of the daytime peak without producing a significant change in the nighttime peak in patients with heart failure. Levels of plasma NA were significantly higher in patients than in normal subjects under all conditions.Thus, in normal subjects xamoterol predominantly increased the slower heart rate at night with only a minor effect on the higher heart rate in the daytime, whereas it predominantly attenuated the daytime tachycardia induced by sympathetic stimulation in patients with heart failure.It is concluded that xamoterol tends overall to act as a-adrenoceptor antagonist during the day, especially in the daytime in patients with mild to moderate heart failure. Its antagonist rather than its agonist effect may account for the long-term efficacy of xamoterol in patients with mild to moderate heart failure. 相似文献
95.
In order to clarify the interaction of volatile anesthetics and extracellular calcium ion on the myocardial contraction, effects of both isoflurane (1.0%) and halothane (0.5%) on the extracellular calcium ion concentration ([Ca2+]O)-tension curve were studied. Increasing [Ca2+]O enhanced the myocardial contraction response, and the maximal response was obtained at [Ca2+]O of 3.0mM. Halothane depressed the maximal value of the tension development in response to increasing [Ca2+]O, while isoflurane did not (P 0.01). The probit response of the developed tension to the changes in [Ca2+]O indicated that isoflurane increased the median effective concentration (EC50) of [Ca2+]O significantly from 0.484 ± 0.051 (mean ± SEM) to 0.870 ± 0.056mM (P = 0.001), but halothane did not (P = 0.018). Therefore, 1.0% isoflurane was concluded to move the [Ca2+]O-tension curve to the right, while a downwards shift occurred with 0.5% halothane.(Saeki S, Hirakawa M, Shimosato S: Effects of Isoflurane and Halothane on the Calcium Ion-tension Curve in Rat Myocardium. J Anesth 6: 172–175, 1992) 相似文献
96.
Manabe Y Shiro Y Warita H Hayashi T Nakashima H Abe K 《Journal of the neurological sciences》2000,178(2):163-166
This is the first report of a patient with venous insufficiency following compressive arachnoiditis ossificans (AO). Symptoms of fluctuating monoplegia and sensory disturbance appeared monthly, lasting several weeks each time. Spinal magnetic resonance imaging (MRI) showed high T2-weighted signal intensity in the posterior portion of the column from T11 to T12 and an intradural lesion with low T2-weighted signal intensity. Neurological function and MRI improved markedly following an operation on AO. The symptoms seen in the present case were due to posterior venous insufficiency following compressive AO. 相似文献
97.
Komai S Matsuyama T Matsumoto K Kato K Kobayashi M Imamura K Yoshida S Ugawa S Shiosaka S 《The European journal of neuroscience》2000,12(4):1479-1486
We found that neuropsin, an extracellular matrix serine protease, has a regulatory effect on Schaffer-collateral long-term potentiation (LTP) in the mouse hippocampus. Bath application of 1-170 nM recombinant neuropsin modulated early phase LTP in the Schaffer-collateral pathway with a 'bell-shape' dose-response curve. The maximum enhancing activity (134% of control LTP) was found at approximately 2.5 nM. Bath application of a neutralizing antibody against neuropsin in the hippocampal slice resulted in a marked inhibition of the tetanus-induced early phase of LTP. The in vivo continuous intraventricular infusion of an antisense oligonucleotide against neuropsin significantly reduced the amplitude of the tetanus-induced early phase of LTP in vitro. Neuropsin did not directly change the N-methyl D-aspartate (NMDA) current. Thus, neuropsin appears to act as a regulatory molecule in the early phase of LTP via its proteolytic function on extracellular matrix rather than affecting NMDA receptor-mediated calcium increase. 相似文献
98.
Peripheral nerve repair and grafting techniques: a review 总被引:3,自引:0,他引:3
In this review, various conventional nerve repair techniques including direct epineurial repair, grouped fascicular repair, fascicular repair, and nerve grafting are described. The indications for use, as well as the relative advantage and disadvantage, of each technique are discussed. The experimental and clinical evidence from a review of the pertinent literature does not demonstrate a significant difference in outcome of one method over the others. Surgical decisions should be made by a thorough evaluation of all aspects of the nerve injury and surgical methods. All nerve injuries cannot be repaired using only one type of nerve repair method. The surgeon should be familiar with all the techniques described and be prepared to use them under appropriate circumstances. 相似文献
99.
100.
Kazushige Kiguchi Masao Iwamori Yukari Mochizuki Takeshi Kishikawa Katsumi Tsukazaki Masahiko Saga Akira Amemiya Shiro Nozawa 《Cancer science》1998,89(9):923-932
Cells of the human tumor cell line RMG-1, derived from a clear-cell adenocarcinoma of the ovary, were injected intraperitoneally into nude mice, and the cells obtained from the tumor nodules in the mesenterium were found to form a larger number of, and larger-sized, tumor nodules than the original RMG-1 cells. The RMG-1-h cells, transferred into culture from the tumor nodules after a 4th in vivo passage, showed a dissemination potential as high as that of cells disseminating directly from the tissues, and exceedingly higher than that of RMG-1 cells. To assess the molecular bases of the different biological properties of RMG-1 and RMG-1-h cells, we compared the content and expression of various carbohydrate antigens in both cells. The chromosomal profile of RMG-1-h cells revealed their human origin and was identical to that of the original RMG-1 cells. In contrast to the broad histogram for the Lex-bearing cells among RMG-1 cells in flow cytometry, the weakly and moderately positive cells toward anti-Lex antibody were found to be eliminated from the histogram for the RMG-1-h cells, resulting in the enrichment of cells strongly expressing Lex, which may account for the high dissemination potential. In addition, the adhesion of RMG-1 cells to mesothelial cells was found to be significantly inhibited by pretreatment of the cells with anti-Lex antibody, indicating Lex-mediated cell-to-cell interaction between ovarian cancer cells and mesothelial cells. By TLC-immunostaining, two Lex-glycolipids, III3Fucα-nLc4Cer and V3Fucα-nLc6Cer were detected in both RMG-1 and RMG-1-h cells, and their total concentrations were not significantly different from each other. However, the hydrophobic moieties of Lex-glycolipids in RMG-1-h cells were different from those in RMG-1 cells, suggesting that a difference in the structure of the hydrophobic moieties of Lex is partly involved in the enhanced reactivity of RMG-1-h cells toward anti-Lex antibody. Thus, the high dissemination potential of ovarian cancer cells was shown to be mediated by the Lex-determinant and the Lex-bearing cells are enriched by repeated in vivo passage of the cells into nude mice. 相似文献