全文获取类型
收费全文 | 3350篇 |
免费 | 280篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 112篇 |
妇产科学 | 77篇 |
基础医学 | 534篇 |
口腔科学 | 94篇 |
临床医学 | 391篇 |
内科学 | 706篇 |
皮肤病学 | 41篇 |
神经病学 | 293篇 |
特种医学 | 200篇 |
外科学 | 249篇 |
综合类 | 27篇 |
一般理论 | 1篇 |
预防医学 | 339篇 |
眼科学 | 77篇 |
药学 | 290篇 |
中国医学 | 4篇 |
肿瘤学 | 230篇 |
出版年
2023年 | 33篇 |
2022年 | 80篇 |
2021年 | 134篇 |
2020年 | 65篇 |
2019年 | 101篇 |
2018年 | 105篇 |
2017年 | 75篇 |
2016年 | 82篇 |
2015年 | 96篇 |
2014年 | 107篇 |
2013年 | 154篇 |
2012年 | 208篇 |
2011年 | 210篇 |
2010年 | 112篇 |
2009年 | 92篇 |
2008年 | 162篇 |
2007年 | 214篇 |
2006年 | 161篇 |
2005年 | 156篇 |
2004年 | 135篇 |
2003年 | 123篇 |
2002年 | 125篇 |
2001年 | 51篇 |
2000年 | 31篇 |
1999年 | 58篇 |
1998年 | 54篇 |
1997年 | 59篇 |
1996年 | 47篇 |
1995年 | 45篇 |
1994年 | 40篇 |
1993年 | 36篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 30篇 |
1989年 | 38篇 |
1988年 | 39篇 |
1987年 | 26篇 |
1986年 | 35篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 17篇 |
1982年 | 29篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 14篇 |
1972年 | 14篇 |
排序方式: 共有3686条查询结果,搜索用时 15 毫秒
101.
Monica Pires Ribeiro Sergio Augusto Lopes de Souza Flavia Paiva Proen?a Lobo Lopes Paulo Henrique Rosado-de-Castro Lea Mirian Barbosa da Fonseca Bianca Gutfilen 《Clinics (S?o Paulo, Brazil)》2013,68(3):283-289
OBJECTIVE:
Mammography has been established as the gold standard for the detection of breast cancer, and imaging techniques such as ultrasonography, magnetic resonance imaging, scintigraphy and positron emission tomography may be useful to improve its sensitivity and specificity. The objective of this study with breast scintigraphy was to evaluate the uptake of 99mTc-thymine in mammary lesions.METHODS:
A total of 45 patients were included in this study. Thirty-three patients (73%) were subjected to surgery or percutaneous biopsy, providing histopathological data. The other 12 patients who remained under surveillance received clinical examinations and biannual mammography with a normal follow-up of at least three years, the data from which were used for comparison with the scintimammography results.RESULTS:
The majority of patients (64.4%) had clinically impalpable lesions with a mammogram diagnosis of microcalcifications, impalpable nodules, or focal asymmetry. Of the studied lesions, 87% were smaller or equal to 20 mm in diameter, and 22% had malignant histopathological findings. Scintigraphy with 99mTc-thymine had a sensitivity of 70%, a specificity of 85.7%, positive and negative predictive values of 58.3% and 90.9%, respectively, and an accuracy of 82.2%.CONCLUSIONS:
The results of this study are consistent with those previously reported by other authors. The good specificity and high negative predictive value of this technique and the absence of uptake in the heart indicate that it may be a promising complementary method in clinical practice and that it may contribute to reducing unnecessary benign biopsies. 相似文献102.
Haroon I. Sheikh Katie R. Kryski Heather J. Smith Lea R. Dougherty Daniel N. Klein Sara J. Bufferd Shiva M. Singh Elizabeth P. Hayden 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2013,162(3):245-252
Catechol‐O‐Methyltransferase (COMT) is a critical regulator of catecholamine levels in the brain. A functional polymorphism of the COMT gene, val158met, has been linked to internalizing symptoms (i.e., depression and anxiety) in adolescents and adults. We extended this research by investigating whether the val158met polymorphism was associated with childhood symptoms of depression and anxiety in two independent samples of young children (Ns = 476 and 409). In both samples, preschool‐aged children were genotyped for the COMT val158met polymorphism. Symptoms of psychopathology were assessed via parent interviews and primary caregiver reports. In both samples, children homozygous for the val allele had higher levels of depressive symptoms compared to children with at least one copy of the met allele. Our findings extend previous research in older participants by showing links between the COMT val158met polymorphism and internalizing symptoms in early childhood. © 2013 Wiley Periodicals, Inc. 相似文献
103.
Objectives
Ultrasonic surgery is an increasingly popular technique for cutting bone, but little research has investigated how the ultrasonic tip oscillations may affect the cuts they produce in bone. The aim of this investigation was to evaluate the oscillation and cutting characteristics of an ultrasonic surgical device.Materials and methods
A Piezosurgery 3 (Mectron, Carasco, Italy) ultrasonic cutting system was utilised with an OP3 style tip. The system was operated with the tip in contact with porcine bone samples (loads of 50 to 200 g) mounted at 45° to the vertical insert tip and with a water flow of 57 ml/min. Tip oscillation amplitude was determined using scanning laser vibrometry. Bone surfaces defects were characterised using laser profilometry and scanning electron microscopy.Results
A positive relationship was observed between the magnitude of tip oscillations and the dimensions of defects cut into the bone surface. Overloading the tip led to a reduction in oscillation and hence in the defect produced. A contact load of 150 g provided the greatest depth of cut. Defects produced in the bone came from two clear phases of cutting.Conclusions
The structure of the bone was found to be an important factor in the cut characteristics following piezosurgery.Clinical relevance
Cutting of bone with ultrasonics is influenced by the load applied and the setting used. Care must be used to prevent the tip from sliding over the bone at low loadings. 相似文献104.
105.
DH Mallon M Kostalas FJ MacPherson A Parmar A Drysdale E Chisholm 《Annals of the Royal College of Surgeons of England》2013,95(4):258-262
Introduction
Fine needle aspiration (FNA) is a safe and quick method of diagnosing superficial lumps, which aids preoperative planning. However, FNA of the parotid gland has not gained the widespread acceptance noted in other head and neck lumps. The aim of this study was to determine the ability of FNA of the parotid gland to differentiate benign and malignant disease, and to determine the impact on surgical outcome.Methods
A retrospective analysis of 201 consecutive parotid operations with preoperative FNA in a large district hospital in the UK was performed. The diagnostic characteristics were calculated for benign and malignant disease, and the impact on surgical procedure was determined.Results
In identifying benign disease, FNA has a sensitivity of 85% and a specificity of 76%. In detecting malignant disease, FNA has a sensitivity and specificity of 52% and 92% respectively. A false positive on FNA was associated with a higher incidence of neck dissection.Conclusions
FNA is a useful diagnostic test. However, owing to low sensitivity, it is necessary to interpret it in the context of all other clinical information. 相似文献106.
There have been significant advances made over the years in the areas of critical care, anesthesia, and surgical technique, which have led to improved mortality rates and survival after resection for pancreatic cancer. The standard of care is currently PD or PPPD for pancreatic cancers of the head, uncinate process, or neck and DP for pancreatic cancers of the body or tail. Resections are performed with the goals of negative margins and minimal blood loss, and referral to high-volume centers and surgeons is encouraged. However, 5-year survival rate after curative resection still remains at less than 20%. In an effort to improve survival and extend the limits of resectability, many centers have attempted extended lymphadenectomy and portal venous and even arterial resection and reconstruction. Extended lymphadenectomy has not led to improved survival for these patients. Portal vein resection has increased the number of patients amenable to resection, with equivalent survival rates compared with those of standard resections. Portal vein invasion is thus no longer considered a contraindication to resection at many large centers. Resection and reconstruction of involved arteries have been rarely performed and are currently not considerations for most patients. It is likely that future improvements in survival lie in the realm of adjuvant therapy. As chemotherapeutic and other tumor-directed agents continue to evolve and advance, this will hopefully lead to improved survival for patients undergoing surgical resection for pancreatic cancer. 相似文献
107.
David P. Goldstein MD Gideon Y. Bachar MD Jane Lea MD Mark G. Shrime MD Rajan S. Patel MB Patrick J. Gullane MB Dale H. Brown MB Ralph W. Gilbert MD John Kim MD Jonathan Waldron MD Bayardo Perez–Ordonez MD Aileen M. Davis PhD Lu Cheng MMath Wei Xu PhD Jonathan C. Irish MD 《Head & neck》2013,35(5):632-641
108.
Lea Tenenholz Grinberg Xuehua Wang Chao Wang Peter Dongmin Sohn Panos Theofilas Manu Sidhu John Benjamin Arevalo Helmut Heinsen Eric J. Huang Howard Rosen Bruce L. Miller Li Gan William W. Seeley 《Acta neuropathologica》2013,125(4):581-593
Post-translational modifications play a key role in tau protein aggregation and related neurodegeneration. Because hyperphosphorylation alone does not necessarily cause tau aggregation, other post-translational modifications have been recently explored. Tau acetylation promotes aggregation and inhibits tau’s ability to stabilize microtubules. Recent studies have shown co-localization of acetylated and phosphorylated tau in AD and some 4R tauopathies. We developed a novel monoclonal antibody against acetylated tau at lysine residue 274, which recognizes both 3R and 4R tau, and used immunohistochemistry and immunofluorescence to probe 22 cases, including AD and another eight familial or sporadic tauopathies. Acetylated tau was identified in all tauopathies except argyrophilic grain disease (AGD). AGD is an age-associated, common but atypical 4R tauopathy, not always associated with clinical progression. Pathologically, AGD is characterized by neuropil grains, pre-neurofibrillary tangles, and oligodendroglial coiled bodies, all recognized by phospho-tau antibodies. The lack of acetylated tau in these inclusions suggests that AGD represents a distinctive tauopathy. Our data converge with previous findings to raise the hypothesis that AGD could play a protective role against the spread of AD-related tau pathology. Tau acetylation as a key modification for the propagation tau toxicity deserves further investigation. 相似文献
109.
Shirley A. Hess Sarah Knox Jill M. Schultz Clara E. Hill Lea Sloan Susan Brandt 《Psychotherapy research》2013,23(4):400-411
Abstract In interviews with 14 counseling center predoctoral interns regarding a significant nondisclosure in supervision, eight interns reported good supervisory relationships and six indicated that they experienced problematic supervisory relationships. Nondisclosures for the interns in good supervisory relationships related to personal reactions to clients, whereas nondisclosures for interns in problematic supervisory relationships related to global dissatisfaction with the supervisory relationship. In both groups, interns mentioned concerns about evaluation and negative feelings as typical reasons for nondisclosure. Additional reasons for nondisclosure for interns in problematic supervision were power dynamics, inhibiting demographic or cultural variables, and the supervisor's theoretical orientation. Both groups described negative effects of nondisclosure on themselves and their relationships with clients. Interns in problematic supervision also reported that nondisclosures had negative effects on the supervisory relationship. 相似文献
110.