全文获取类型
收费全文 | 15080篇 |
免费 | 1361篇 |
国内免费 | 64篇 |
专业分类
耳鼻咽喉 | 202篇 |
儿科学 | 343篇 |
妇产科学 | 225篇 |
基础医学 | 2002篇 |
口腔科学 | 215篇 |
临床医学 | 1547篇 |
内科学 | 3253篇 |
皮肤病学 | 379篇 |
神经病学 | 937篇 |
特种医学 | 604篇 |
外科学 | 2561篇 |
综合类 | 108篇 |
现状与发展 | 1篇 |
一般理论 | 4篇 |
预防医学 | 1257篇 |
眼科学 | 510篇 |
药学 | 1116篇 |
中国医学 | 83篇 |
肿瘤学 | 1158篇 |
出版年
2024年 | 13篇 |
2023年 | 151篇 |
2022年 | 122篇 |
2021年 | 768篇 |
2020年 | 449篇 |
2019年 | 550篇 |
2018年 | 638篇 |
2017年 | 423篇 |
2016年 | 502篇 |
2015年 | 518篇 |
2014年 | 653篇 |
2013年 | 703篇 |
2012年 | 1117篇 |
2011年 | 1086篇 |
2010年 | 645篇 |
2009年 | 516篇 |
2008年 | 897篇 |
2007年 | 880篇 |
2006年 | 748篇 |
2005年 | 698篇 |
2004年 | 616篇 |
2003年 | 539篇 |
2002年 | 493篇 |
2001年 | 493篇 |
2000年 | 451篇 |
1999年 | 369篇 |
1998年 | 120篇 |
1997年 | 100篇 |
1996年 | 87篇 |
1995年 | 75篇 |
1994年 | 66篇 |
1993年 | 58篇 |
1992年 | 148篇 |
1991年 | 103篇 |
1990年 | 118篇 |
1989年 | 107篇 |
1988年 | 92篇 |
1987年 | 79篇 |
1986年 | 65篇 |
1985年 | 54篇 |
1984年 | 47篇 |
1983年 | 32篇 |
1982年 | 19篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 56 毫秒
31.
Mohammad-Reza Movahed Tony Ngoc Nguyen Kent McAllister Jenchen Yang 《Cardiovascular Revascularization Medicine》2006,7(3):189-191
We present a case of intermittent cessation of blood flow through stent struts during systole, with normal flow during diastole in the previously stented ostial vein graft. After reviewing the initial procedure, we discovered that the operator had difficulty in positioning the stent. After stent deployment, the ostial stent was malpositioned and was protruding more than 50% into the aorta. During systole, the contrast in the stent struts, which are situated in the aorta, was being washed off by systolic blood flow, while in the diastole, the flow of contrast was normal. This is the first case report of this observation with a brief review. 相似文献
32.
Resolution of homonymous visual field loss documented with functional magnetic resonance and diffusion tensor imaging. 总被引:5,自引:0,他引:5
Masaki Yoshida Masahiro Ida Thien Huong Nguyen Marie-Therese Iba-Zizen Luc Bellinger Jean Louis Stievenart Takehiko Nagao Shinsuke Kikuchi Takaaki Hara Takuya Shiba Kenji Kitahara Emmanuel Alain Cabanis 《Journal of neuro-ophthalmology》2006,26(1):11-17
A 68-year-old man developed right homonymous hemianopic paracentral scotomas from acute infarction of the left extrastriate area. He was studied over the ensuing 12 months with visual fields, conventional MRI, functional MRI (fMRI), and diffusion tensor imaging (DTI). As the visual field defect became smaller, fMRI demonstrated progressively larger areas of cortical activation. DTI initially showed that the lesioned posterior optic radiations were completely interrupted. This interruption lessened in time and had disappeared by one year after onset. fMRI and DTI are innovative measures to follow functional and structural recovery in the central nervous system. This is the first reported application of these imaging techniques to acute cerebral visual field disorders. 相似文献
33.
Comparison of dynamic and step-and-shoot intensity-modulated radiation therapy planning and delivery. 总被引:1,自引:0,他引:1
Intensity-modulated radiation therapy (IMRT) is commonly delivered using the dynamic or segmental mode of multileaf collimators (DMLC or SMLC). Both methods are designed to deliver intensity-modulated beams as determined by inverse planning software. In this study, we have used the Helios IMRT planning system to generate ideal treatment plans for 10 cases of 2 common treatment sites (prostate and head and neck) and have investigated the actual treatment fluence distributions generated for each of the MLC leaf motion choices. The 2 dose delivery techniques were dosimetrically compared to each other and to the treatment plans. For each technique, point doses were measured in a water phantom using ionization chambers. Also for each technique, 2-dimensional dose distributions at a selected depth in a plastic phantom were obtained, using extended range film. The total delivery time and the number of monitor units (MU) delivered by each method were also compared. Our results indicate that the 2 delivery methods produce comparable results dosimetrically. For the cases reviewed, the delivery time was an average of 15% longer for SMLC deliveries, while the number of MUs (beam-on time) required by SMLC was an average of 15% fewer, than that for the DMLC. In the interest of simplicity, lower beam-on time, and potentially fewer mechanically-related problems, we think that the SMLC delivery technique may be the better choice when Helios is used for planning and Varian linear accelerators are used for delivery. 相似文献
34.
Regnier V; Meddeb M; Lecointre G; Richard F; Duverger A; Nguyen VC; Dutrillaux B; Bernheim A; Danglot G 《Human molecular genetics》1997,6(1):9-16
Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase
activating protein family and is considered to be a tumor suppressor gene.
Its very high rate of de novo mutation in humans led us to study a specific
feature of this gene: the presence of numerous NF1-related sequences.
According to our results, the human genome contains at least 11 NF1-related
sequences, nine of which are scattered near centromeric sequences of seven
different chromosomes. These NF1-related sequences, whose extent is quite
varied according to loci, are unprocessed copies of the NF1 gene, and bear
numerous mutations. A phylogenetic analysis of the six largest sequences
indicates that they are all derived from a common ancestor, which would
have appeared 22-33 million years ago, and was subsequently duplicated
several times during hominoid evolution. The most recent duplication and
interchromosomal transposition occurred in the last million years
suggesting that the process could still be ongoing. Intriguing similarities
between the evolution of alpha- satellite DNA and NF1-related sequences
suggest the involvement of a common genetic mechanism for the generation
and pericentric spreading of these NF1 partial copies.
相似文献
35.
In pinning a slipped capital femoral epiphysis (SCFE), the position of the pin within the center of the femoral head is important for two reasons. The pin may disrupt the lateral epiphyseal artery and cause avascular necrosis (AVN), or pin penetration in certain locations may go unrecognized on radiographs. To place the pin accurately, the surgeon must be aware of where the femoral head lies in relation to the femoral neck and the shaft. Radiographs of models and of patients in various positions support the view that the femoral head in most cases of chronic SCFE rotates around the axis of the femoral neck and does not slip inferiorly. Therefore, the starting point for an in situ fixation device is the anterior femoral neck, the exact location depending on the amount of slipping. 相似文献
36.
Morphine place conditioning is differentially affected by CCKA and CCKB receptor antagonists. 总被引:2,自引:0,他引:2
In the present study we have examined the interaction between the selective cholecystokinin (CCK)A and CCKB receptor antagonists, devazepide and L365-260 on morphine conditioned place preference (CPP). Using an unbiased procedure, morphine (1.5 mg/kg) produced a reliable CPP which was observed irrespective of the conditioning compartment type. Pretreatment with devazepide (0.001-0.01 mg/kg s.c.) produced a dose related attenuation of this response. At higher doses (0.1-1 mg/kg) this antagonism became variable and dependent on the training compartment with blockade only observed when conditioning was to the white/rough textured environment. This profile has also been reported for the serotonin (5-HT)3 receptor antagonist ondansetron. The CCKB antagonist L365-260 (0.000001-0.01 mg/kg) failed to antagonize the morphine CPP, if anything a mild potentiation was observed. To study this further we examined the interaction between L365-260 (0.01 mg/kg) and a subthreshold dose of morphine (0.3 mg/kg). At these doses neither drug elicited CPP, however when co-administered a significant CPP was recorded. Finally, L365-260 at 1 mg/kg induced a mild but significant CPP when administered alone. These results suggest a differential role of CCK receptor subtypes on reward-related behaviour and complement previous studies suggesting bimodal effects of CCK systems on mesolimbic dopamine function. 相似文献
37.
D Nguyen I Abdul-Rasool D Ward J Hsieh D Kobayashi S Hadlock F Singer B Bloor 《Anesthesiology》1992,76(4):573-579
Dexmedetomidine (DMED) is a novel alpha 2 adrenergic agonist that has been shown to have potent analgesic and anesthetic sparing effects. This study was designed to investigate the effects of DMED, both alone and combined with isoflurane, on resting ventilation, the hypercapnic response, and the hypoxic response in dogs. When given alone, 1 microgram/kg decreased resting ventilation by 22% but at larger doses (10, 20, and 100 micrograms/kg) resting ventilation increased, doubling at 100 micrograms/kg. Doses of 10 micrograms/kg and greater caused a maximum depression of 60% in the slope of the hypercapnic response, but no dose had a significant effect on the hypoxic ventilatory response. A dose of 3 micrograms/kg of DMED reduced isoflurane MAC from 1.3% to 0.37%, and the ventilatory effects of this 1 MAC combination were intermediate between the awake values and those of isoflurane-anesthetized (1.3%) dogs. Atipamezole is a specific centrally acting alpha 2 receptor antagonist and when given with DMED in isoflurane-anesthetized dogs prevented the ventilatory depression. However, atipamezole alone also ventilatory stimulating effects, which may indicate tonic alpha 2 adrenergic activity. The ventilatory depression caused by DMED, either alone or combined with isoflurane, at doses that significantly reduce anesthetic requirements are relatively mild. 相似文献
38.
39.
Marenne P Budde Titia E De Lange Gus A Dekker Annabelle Chan Anh-Minh T Nguyen 《The journal of maternal-fetal & neonatal medicine》2007,20(9):687-693
OBJECTIVE: This study was undertaken in order to determine the risk factors for pregnancies complicated by placental abruption in a socio-economically disadvantaged region in metropolitan Adelaide. METHODS: This was a retrospective case-control study including all singleton pregnancies resulting in placental abruption between 2001 and 2005. RESULTS: The overall incidence of placental abruption was 1.0%; the overall perinatal mortality among the births with abruption was 13%. Univariate analyses showed the following significant risk factors for placental abruption: preterm pre-labor rupture of the membranes (PRE-PROM; odds ratio (OR) 4.79, 95% confidence interval (CI) 1.52-15.08), non-compliance with antenatal care (OR 2.93, 95% CI 1.06-8.90), severe intrauterine growth restriction (IUGR), and elevated homocysteine levels (OR 45.55, 95% CI 7.05-458.93). Severe IUGR was significantly more common in the abruption group compared with the control group (p = 0.032). In the multivariate analysis, PRE-PROM remained a significant independent risk factor for placental abruption. Marijuana use, domestic violence, and mental health problems were more common (borderline significance) in the abruption group. Smoking and preeclampsia were not found to be associated with placental abruption in this study. CONCLUSIONS: In this high-risk population, PRE-PROM and elevated homocysteine levels appear to represent the major risk factors for placental abruption. 相似文献
40.
J W Ellingboe W Spinelli M W Winkley T T Nguyen R W Parsons I F Moubarak J M Kitzen D Von Engen J F Bagli 《Journal of medicinal chemistry》1992,35(4):705-716
The synthesis and Class III antiarrhythmic activity of a series of 4-[(methylsulfonyl)amino]benzamides and sulfonamides are described. Selected compounds show a potent Class III activity and are devoid of effects on conduction both in vitro (dog Purkinje fibers) and in vivo (anesthetized dogs). Compounds having a 2-aminobenzimidazole group were found to be the most potent, and one compound having this heterocycle (5, WAY-123,398) was selected for further characterization. Compound 5 was shown to have good oral bioavailability and a favorable hemodynamic profile to produce a 3-fold increase of the ventricular fibrillation threshold and to terminate ventricular fibrillation, restoring sinus rhythm in anesthetized dogs. Voltage-clamp studies in isolated myocytes show that 5 is a potent and specific blocker of the delayed rectifier potassium current (IK) at concentrations that cause significant prolongation of action potential duration. 相似文献