全文获取类型
收费全文 | 179372篇 |
免费 | 1308篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 1150篇 |
儿科学 | 6712篇 |
妇产科学 | 3046篇 |
基础医学 | 17186篇 |
口腔科学 | 1606篇 |
临床医学 | 12836篇 |
内科学 | 31516篇 |
皮肤病学 | 747篇 |
神经病学 | 17115篇 |
特种医学 | 9102篇 |
外科学 | 29131篇 |
综合类 | 2341篇 |
一般理论 | 6篇 |
预防医学 | 18401篇 |
眼科学 | 2795篇 |
药学 | 9717篇 |
1篇 | |
中国医学 | 629篇 |
肿瘤学 | 16659篇 |
出版年
2023年 | 50篇 |
2022年 | 86篇 |
2021年 | 175篇 |
2020年 | 124篇 |
2019年 | 181篇 |
2018年 | 22050篇 |
2017年 | 17477篇 |
2016年 | 19647篇 |
2015年 | 1079篇 |
2014年 | 1001篇 |
2013年 | 982篇 |
2012年 | 7322篇 |
2011年 | 21334篇 |
2010年 | 18988篇 |
2009年 | 11693篇 |
2008年 | 19772篇 |
2007年 | 21979篇 |
2006年 | 782篇 |
2005年 | 2364篇 |
2004年 | 3539篇 |
2003年 | 4493篇 |
2002年 | 2591篇 |
2001年 | 302篇 |
2000年 | 443篇 |
1999年 | 197篇 |
1998年 | 228篇 |
1997年 | 220篇 |
1996年 | 103篇 |
1995年 | 115篇 |
1994年 | 106篇 |
1993年 | 63篇 |
1992年 | 54篇 |
1991年 | 99篇 |
1990年 | 137篇 |
1989年 | 85篇 |
1988年 | 61篇 |
1987年 | 49篇 |
1986年 | 34篇 |
1985年 | 48篇 |
1984年 | 25篇 |
1983年 | 29篇 |
1982年 | 28篇 |
1980年 | 43篇 |
1974年 | 25篇 |
1969年 | 24篇 |
1938年 | 60篇 |
1937年 | 25篇 |
1934年 | 30篇 |
1932年 | 57篇 |
1930年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
61.
Dan Greitz 《Child's nervous system》2007,23(5):487-489
Objective This study aims to question the generally accepted cerebrospinal fluid (CSF) bulk flow theory suggesting that the CSF is exclusively
absorbed by the arachnoid villi and that the cause of hydrocephalus is a CSF absorption deficit. In addition, this study aims
to briefly describe the new hydrodynamic concept of hydrocephalus and the rationale for endoscopic third ventriculostomy (ETV)
in communicating hydrocephalus.
Critique The bulk flow theory has proven incapable of explaining the pivotal mechanisms behind communicating hydrocephalus. Thus, the
theory is unable to explain why the ventricles enlarge, why the CSF pressure remains normal and why some patients improve
after ETV.
Hydrodynamic concept of hydrocephalus Communicating hydrocephalus is caused by decreased intracranial compliance increasing the systolic pressure transmission into
the brain parenchyma. The increased systolic pressure in the brain distends the brain towards the skull and simultaneously
compresses the periventricular region of the brain against the ventricles. The final result is the predominant enlargement
of the ventricles and narrowing of the subarachnoid space. The ETV reduces the increased systolic pressure in the brain simply
by venting ventricular CSF through the stoma. The patent aqueduct in communicating hydrocephalus is too narrow to vent the
CSF sufficiently. 相似文献
62.
Christian Waydhas Dieter Nast-Kolb Steffen Ruchholtz 《European journal of trauma and emergency surgery》2007,33(2):170-175
Abstract
Objective: To define the diagnostic accuracy of clinical examination in patients with impaired consciousness or endotracheal intubation
to detect pelvic ring fractures and to identify those with severe bleeding.
Methods: Included in this prospective data collection with retrolective data analysis were a consecutive series of blunt trauma victims
with either a Glasgow Coma Scale ≤ 13 or tracheal intubation. Clinical examination comprised testing for stability of the
iliac wings.
Results: From 784 subjects (injury severity score 23.3 ± 17.4) 93 patients (11.9%) were found to have a pelvic ring fracture. Clinical
instability of the pelvic ring was found in 42 patients. There was only one false positive. Fifty-two fractures could not
be identified by clinical examination, including nine fractures (17%) that required surgical fracture stabilization (sensitivity
of clinical examination 44.1%). Seventeen fractures (18.3%) were associated with a blood loss larger than 20% of circulating
blood volume. Sixteen of those were identified by clinical instability of the pelvic ring (sensitivity 94.1%, specificity
97.0%, positive predictive value 38.1%, negative predictive value 99.9%).
Conclusions: Clinical examination for stability of the pelvis in this selected group of patients missed a significant number of pelvic
ring fractures including fractures that require surgical stabilization. The finding of a clinically unstable identifies most
of the patients with the pelvic ring fracture being a major source of bleeding. A stable pelvis makes pelvic ring fracture
as being the source of bleeding quite unlikely. 相似文献
63.
Dr. med. Dr. med. dent. Christof Holberg Katja Schwenzer Ingrid Rudzki-Janson 《Journal of orofacial orthopedics》2005,66(2):110-121
Abstract
Background and Aim:
The prediction of soft tissue esthetics is important for achieving an optimal esthetic outcome in orthodontic treatment planning. Applicable procedures have so far been restricted to two-dimensional profile predictions that have not proven to be very reliable. The goal of this investigation was therefore to develop a novel finite element-based procedure that allows a three-dimensional, easily visualized, quantitative analysis and prediction of soft tissue behavior for the clinician. The procedure to be developed should be easy to handle and not entail any additional radiation exposure for the patient.
Material and Methods:
Using a three-dimensional scanner, the facial surfaces of 20 probands were digitalized and individual FEM models were generated.
Results:
After reduction of data redundancy via several conversion steps, a patient-specific simulation model was prepared consisting of 20,000 to 40,000 individual elements to which specific physical properties could be assigned. The average time required for generating a virtual model was 50 minutes. Problems occurring during model generation were rare (mainly shadowing phenomena and movement artifacts).
Conclusion:
The procedure outlined herein makes the reliable generation of patient-specific simulation models possible for facial soft tissue prediction in orthodontics. 相似文献
64.
Background
Reports on childhood cancer survivors estimated cumulative probability of developing secondary neoplasms vary from 3,3% to 25% at 25 years from diagnosis, and the risk of developing another cancer to several times greater than in the general population. 相似文献65.
Dr. med. Dr. med. dent. Christof Holberg Anne-Kathrin Heine Philipp Geis Katja Schwenzer Ingrid Rudzki-Janson 《Journal of orofacial orthopedics》2005,66(2):122-134
BACKGROUND AND AIM: The goal of this study was to analyze the validity and prediction accuracy of a newly-developed procedure for three-dimensional soft tissue prediction based on Finite Element Method, and to compare the results with prediction produced using an existing two-dimensional prediction program (Dentofacial Planner Plus). PATIENTS AND METHODS: In twelve patients who underwent combined surgical-orthodontic treatment, profile prediction was generated using both procedures preoperatively and then compared at predefined measurement points with the patient's actual postoperative soft tissue status. RESULTS: The deviations observed depended on the facial region, whereby the prediction errors for both procedures were much greater in the lower facial third than in the midfacial third. Calculating in all the measurement points, the mean horizontal prediction error was 0.32 mm for the Finite Element Method and 0.75 mm for the Dentofacial Planner Plus. Overall, we were able to demonstrate the new procedure's superior validity and quality of visualization. In addition to profile prediction, the procedure allows a differentiated three-dimensional assessment of esthetically important regions such as the cheeks, nasolabial folds and the nasal wings. Additional X-radiation is not necessary in this risk-free and stress-free procedure. CONCLUSION: Three-dimensional soft tissue prediction employing finite element modeling is a useful aid for implementing esthetically-optimized treatment planning. 相似文献
66.
67.
Birgitta Malmberg Göran Kecklund Björn Karlson Roger Persson Per Flisberg Palle Ørbaek 《BMC health services research》2010,10(1):239
Background
It is well known that physicians' night-call duty may cause impaired performance and adverse effects on subjective health, but there is limited knowledge about effects on sleep duration and recovery time. In recent years occupational stress and impaired well-being among anaesthesiologists have been frequently reported for in the scientific literature. Given their main focus on handling patients with life-threatening conditions, when on call, one might expect sleep and recovery to be negatively affected by work, especially in this specialist group. The aim of the present study was to examine whether a 16-hour night-call schedule allowed for sufficient recovery in anaesthesiologists compared with other physician specialists handling less life-threatening conditions, when on call. 相似文献68.
David Berrigan Linda W Pickle Jennifer Dill 《International journal of health geographics》2010,9(1):20
Background
Past studies of associations between measures of the built environment, particularly street connectivity, and active transportation (AT) or leisure walking/bicycling have largely failed to account for spatial autocorrelation of connectivity variables and have seldom examined both the propensity for AT and its duration in a coherent fashion. Such efforts could improve our understanding of the spatial and behavioral aspects of AT. We analyzed spatially identified data from Los Angeles and San Diego Counties collected as part of the 2001 California Health Interview Survey. 相似文献69.
Sebastiana Z. Kalula G. H. Swingler A. A. Sayer M. Badri M. Ferreira 《The journal of nutrition, health & aging》2010,14(4):319-323
Objective
To test the effects of the use of a collapsible, portable chair (chair B), as opposed to a ‘standard’ chair (chair A), on the outcome of the timed “Up and Go” (TUG) test. 相似文献70.