全文获取类型
收费全文 | 9397篇 |
免费 | 531篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 123篇 |
儿科学 | 200篇 |
妇产科学 | 154篇 |
基础医学 | 1138篇 |
口腔科学 | 868篇 |
临床医学 | 736篇 |
内科学 | 2103篇 |
皮肤病学 | 205篇 |
神经病学 | 657篇 |
特种医学 | 476篇 |
外科学 | 930篇 |
综合类 | 55篇 |
一般理论 | 4篇 |
预防医学 | 1019篇 |
眼科学 | 164篇 |
药学 | 689篇 |
中国医学 | 98篇 |
肿瘤学 | 361篇 |
出版年
2023年 | 81篇 |
2022年 | 228篇 |
2021年 | 352篇 |
2020年 | 252篇 |
2019年 | 286篇 |
2018年 | 351篇 |
2017年 | 228篇 |
2016年 | 255篇 |
2015年 | 325篇 |
2014年 | 454篇 |
2013年 | 484篇 |
2012年 | 671篇 |
2011年 | 819篇 |
2010年 | 393篇 |
2009年 | 336篇 |
2008年 | 549篇 |
2007年 | 561篇 |
2006年 | 401篇 |
2005年 | 409篇 |
2004年 | 313篇 |
2003年 | 307篇 |
2002年 | 252篇 |
2001年 | 166篇 |
2000年 | 149篇 |
1999年 | 132篇 |
1998年 | 85篇 |
1997年 | 87篇 |
1996年 | 71篇 |
1995年 | 39篇 |
1994年 | 55篇 |
1993年 | 40篇 |
1992年 | 50篇 |
1991年 | 77篇 |
1990年 | 58篇 |
1989年 | 69篇 |
1988年 | 53篇 |
1987年 | 56篇 |
1986年 | 60篇 |
1985年 | 53篇 |
1984年 | 45篇 |
1983年 | 41篇 |
1982年 | 30篇 |
1981年 | 37篇 |
1980年 | 20篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1975年 | 20篇 |
1973年 | 14篇 |
1966年 | 13篇 |
排序方式: 共有9980条查询结果,搜索用时 0 毫秒
991.
Eduardo Lima Garcia Márcio Garcia Menezes Charles de Moraes Stefani Luiz Cláudio Danzmann Marco Antonio Rodrigues Torres 《Arquivos brasileiros de cardiologia》2015,105(3):248-255
Background
Heart failure with preserved ejection fraction is a syndrome characterized by changes in diastolic function; it is more prevalent among the elderly, women, and individuals with systemic hypertension (SH) and diabetes mellitus. However, in its early stages, there are no signs of congestion and it is identified in tests by adverse remodeling, decreased exercise capacity and diastolic dysfunction.Objective
To compare doppler, echocardiographic (Echo), and cardiopulmonary exercise test (CPET) variables - ergospirometry variables - between two population samples: one of individuals in the early stage of this syndrome, and the other of healthy individuals.Methods
Twenty eight outpatients diagnosed with heart failure according to Framingham’s criteria, ejection fraction > 50% and diastolic dysfunction according to the european society of cardiology (ESC), and 24 healthy individuals underwent Echo and CPET.Results
The group of patients showed indexed atrial volume and left ventricular mass as well as E/E’ and ILAV/A´ ratios significantly higher, in addition to a significant reduction in peak oxygen consumption and increased VE/VCO2 slope, even having similar left ventricular sizes in comparison to those of the sample of healthy individuals.Conclusion
There are significant differences between the structural and functional variables analyzed by Echo and CPET when comparing two population samples: one of patients in the early stage of heart failure with ejection fraction greater than or equal to 50% and another of healthy individuals. 相似文献992.
Carolina M Vicente Marcelo A Lima Helena B Nader Leny Toma 《Journal of experimental & clinical cancer research : CR》2015,34(1)
Background
SULF2 is a 6-O-endosulfatase which removes 6-O sulfate residues from N-glucosamine present on heparan sulfate (HS). The sulfation pattern of HS influences signaling events mediated by heparan sulfate proteoglycans (HSPGs) located on cell surface, which are critical for the interactions with growth factors and their receptors. Alterations in SULF2 expression have been identified in the context of several cancer types but its function in cancer is still unclear where the precise molecular mechanism involved has not been fully deciphered. To further investigate SULF2 role in tumorigenesis, we overexpressed such gene in prostate cancer cell lines.Methods
The normal prostate epithelial cell line RWPE-1 and the prostate cancer cells DU-145, and PC3 were transfected with SULF2-expressing plasmid pcDNA3.1/Myc-His(−)-Hsulf-2. Transfected cells were then submitted to viability, migration and colony formation assays.Results
Transfection of DU-145 and PC3 prostate cancer cells with SULF2 resulted in increased viability, which did not occur with normal prostate cells. The effect was reverted by the knockdown of SULF2 using specific siRNAs. Furthermore, forced expression of SULF2 augmented cell migration and colony formation in both prostate cell lines. Detailed structural analysis of HS from cells overexpressing SULF2 showed a reduction of the trisulfated disaccharide UA(2S)-GlcNS(6S). There was an increase in epithelial-mesenchymal transition markers and an increase in WNT signaling pathway.Conclusions
These results indicate that SULF2 have a pro-tumorigenic effect in DU-145 and PC3 cancer cells, suggesting an important role of this enzyme in prostatic cancer metastasis. 相似文献993.
Kaliane Rocha Soledade‐Marques Isaac Suzart Gomes‐Filho Simone Seixas da Cruz Johelle de Santana Passos‐Soares Soraya Castro Trindade Eneida de Moraes Marcílio Cerqueira Julita Maria Freitas Coelho Maurício Lima Barreto Maria da Conceição Nascimento Costa Maria Isabel Pereira Vianna Frank A. Scannapieco Álvaro Augusto Cruz Adelmir Souza‐Machado 《Oral diseases》2018,24(3):442-448
994.
Victor Aquino Wanderley Deborah Queiroz Freitas Francisco Haiter-Neto Matheus Lima Oliveira 《Journal of endodontics》2018,44(7):1168-1172
Introduction
The purpose of this study was to assess the influence of tooth orientation in relation to the projection plane of the x-rays on the detection of vertical root fracture (VRF) with different filling materials using cone-beam computed tomographic (CBCT) imaging.Methods
Thirty single-rooted human teeth were endodontically instrumented, and VRF was induced in half of the sample. The roots were individually placed in the dental socket of a phantom head composed of a dry human skull and mandible, and CBCT images were obtained of each root with the longitudinal axis in 2 orientations: perpendicular and parallel to the projection plane of the x-rays. Also, each root was scanned under 3 filling conditions: without filling material, with gutta-percha, and with a metal post. Radiation doses at specific anatomic regions of the phantom were obtained for the 2 orientations. Five radiologists evaluated all images and rated the fractures on a 5-point scale. The sensitivity, specificity, accuracy, and positive and negative predictive values were calculated. The area under the receiver operating characteristic curve and the dosimetric outcomes for each root orientation and filling material were compared, respectively, with 2-way and 1-way analysis of variance with the post hoc Tukey test (α = 0.05).Results
There was no significant difference (P ≥ .05) in the detection of VRF between root orientations regardless of the filling material. Az values were significantly lower (P < .05) in the presence of gutta-percha and a metal post. The root orientation varied the absorbed dose at some anatomic regions.Conclusions
The orientation of the tooth in relation to the projection plane of the x-rays does not influence the detection of VRF using CBCT imaging irrespective of the intracanal material. 相似文献995.
996.
Ricardo Lima Shintcovsk Roberto Soares da Silva Júnior Larry White Lidia Parsekian Martins Renato Parsekian Martins 《The Angle orthodontist》2018,88(5):611
Objectives:To evaluate if a 0.5-mm vertical bend applied on an incisor bracket produces movements in other planes and if different wires influence these effects.Materials and Methods:An acrylic model of a treated patient with brackets passively bonded was attached to an Orthodontic Force Tester, and a load cell was attached to the left lateral incisor. Thirty 0.019 × 0.025-inch archwires were divided into three groups according to their alloy: SS (stainless steel), B-Ti (beta-titanium), and MF (beta-titanium wire coated with nickel-titanium). Step-bends of 0.5 mm high were placed on the lateral incisor bracket using a universal plier, and the forces and moments in three dimensions were statistically analyzed by analysis of variance and Tukey post hoc test.Results:SS produced a larger force (3.4 N) than the B-Ti (1.41 N) and the MF (0.53 N; P < .001). Lingual forces were produced by the SS (0.82 N) and B-Ti (0.31 N) groups, while in the MF group, the force was insignificant. SS produced a mesial force of 0.24 N, while the B-Ti force was insignificant and MF produced 0.09 N. Groups produced different crown-distal tipping moments (SS = 31.48 N-mm, B-Ti = 11.7 N-mm, and MF = 4.55 N-mm) and different crown-buccal tipping moments. SS produced larger moments (3.63 N-mm) than B-Ti (1.02 N-mm) and MF (0.36 N-mm) wires. A mesial-out rotational moment was observed in all groups (SS = 7.17 N-mm, B-Ti = 3.46 N-mm, and MF = 0.86 N-mm).Conclusions:A 0.5-mm intrusion bend produced lingual and mesial side effects. In addition to the distal and buccal crown-tipping moments, there was a mesial-out moment. Compared with SS, B-Ti and MF wires produced lower forces. These more flexible wires showed side effects with lesser intensity. 相似文献
997.
Efficacy of an unwaxed dental floss impregnated with 2% chlorhexidine on control of supragingival biofilm: A randomized,clinical trial 下载免费PDF全文
998.
999.
1000.
Natalin RA Lima FS Pinheiro T Vicari E Ortiz V Andreoni C Landman J 《International braz j urol : official journal of the Brazilian Society of Urology》2012,38(1):4-16
Despite significant advances in laparoscopic technique and technologies, laparoscopic Urologic surgery remains technically demanding regarding various surgical steps including the challenge of specimen retrieval and extraction, whether to install a drainage system and the best option for wound closure. Laparoscopic specimen entrapment and extraction occurs at what is falsely considered the ″end of the procedure″. During open surgery, after the specimen has been mobilized, the specimen is simply lifted out of the larger incision which has been made to achieve the surgical objectives. In contrast, significant laparoscopic skill is required to entrapand safely extract laparoscopic specimens. Indeed, the Urologist and surgical team which are transitioning from open surgery may disregard this important part of the procedure which may lead to significant morbidity. As such, it is imperative that during laparoscopic procedures, the ″end of the procedure″ be strictly defined as the termination of skin closure and dressing placement. Taking a few minutes to focus on safe specimen entrapment and extraction will substantially reduce major morbidity. The following review focus on the technology and technique of specimen entrapment and extraction, on the matter of whether to install a drainage system of the abdominal cavity and the options for adequate closure of trocar site wounds. This article 's primary objectives are to focus on how to minimize morbidity while maintain the advantages of a minimally invasive surgical approach. 相似文献