全文获取类型
收费全文 | 48838篇 |
免费 | 3271篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 524篇 |
儿科学 | 1231篇 |
妇产科学 | 858篇 |
基础医学 | 6395篇 |
口腔科学 | 1249篇 |
临床医学 | 4749篇 |
内科学 | 9949篇 |
皮肤病学 | 725篇 |
神经病学 | 4778篇 |
特种医学 | 2551篇 |
外国民族医学 | 6篇 |
外科学 | 7211篇 |
综合类 | 592篇 |
一般理论 | 40篇 |
预防医学 | 4020篇 |
眼科学 | 1199篇 |
药学 | 2926篇 |
中国医学 | 69篇 |
肿瘤学 | 3225篇 |
出版年
2023年 | 204篇 |
2022年 | 346篇 |
2021年 | 807篇 |
2020年 | 612篇 |
2019年 | 810篇 |
2018年 | 951篇 |
2017年 | 773篇 |
2016年 | 914篇 |
2015年 | 1050篇 |
2014年 | 1468篇 |
2013年 | 2043篇 |
2012年 | 3102篇 |
2011年 | 3285篇 |
2010年 | 1866篇 |
2009年 | 1707篇 |
2008年 | 3054篇 |
2007年 | 3144篇 |
2006年 | 3105篇 |
2005年 | 3036篇 |
2004年 | 2843篇 |
2003年 | 2759篇 |
2002年 | 2655篇 |
2001年 | 613篇 |
2000年 | 567篇 |
1999年 | 634篇 |
1998年 | 602篇 |
1997年 | 469篇 |
1996年 | 421篇 |
1995年 | 402篇 |
1994年 | 322篇 |
1993年 | 292篇 |
1992年 | 370篇 |
1991年 | 338篇 |
1990年 | 308篇 |
1989年 | 325篇 |
1988年 | 292篇 |
1987年 | 308篇 |
1986年 | 279篇 |
1985年 | 300篇 |
1984年 | 305篇 |
1983年 | 292篇 |
1982年 | 318篇 |
1981年 | 297篇 |
1980年 | 263篇 |
1979年 | 225篇 |
1978年 | 233篇 |
1977年 | 195篇 |
1976年 | 168篇 |
1975年 | 177篇 |
1974年 | 183篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The authors present the third installment of the guidelines and recommendations from the Safety Committee of the Society for Magnetic Resonance Imaging (now the Society of Magnetic Resonance) concerning various issues related to the safety and management of patients undergoing magnetic resonance (MR) procedures. This document was developed to provide standardized and consistent information for use by health practitioners involved in screening patients or other individuals for MR procedures. 相似文献
92.
Frank Diesner Dr. med. Dag Moskopp Christoph Schul Hansdetlef Wassmann 《Neurosurgical review》1997,20(4):274-277
A 21-year-old man was injured by a tailboard of a truck. He suffered a severe head injury with bilateral depressed skull fractures necessitating surgical decompression. On admission to the hospital the patient showed bending to pain stimuli (Glasgow Coma Score 5). Anisocoria was noticed from the beginning. Initial intracranial pressure (ICP), measured 3 hours after injury, was 30 mm Hg, and the cerebral perfusion pressure (CPP) was 70 mm Hg. During surgical elevation of the skull fracture on the right side an unexplainable rise of ICP to values of 100 mm Hg occurred, which corresponded to the mean arterial blood pressure (MAP). At the same time both pupils were dilated and fixed indicating a lack of cerebral perfusion. Due to immediate trephination of the opposite side, the ICP was lowered to values below 20 mm Hg, and sufficient cerebral perfusion (above 50 mm Hg) was regained. The patient showed a good recovery and was transferred to a rehabilitation center 5 weeks after injury.This case report emphasizes the importance of early and continuous intracranial pressure monitoring for adequate therapy in neurosurgical emergencies. 相似文献
93.
94.
Sidestream versus mainstream carbon dioxide analyzers 总被引:1,自引:0,他引:1
95.
Ex vivo testing techniques were used to determine the ferromagnetic qualities of, presence of heating in, and artifacts produced by 13 different heart valve prostheses exposed to a 1.5-T (64-MHz) magnetic resonance (MR) system. None of the heart valve prostheses showed a measurable deflection in the 1.5-T static magnetic field. Only minimal artifacts were produced during MR imaging with a fast spoiled GRASS (gradient-recalled acquisition in the steady state) pulse sequence. The largest temperature changes measured during a “worst case” MR imaging sequence (estimated average specific absorption rate, 2.5 W/kg; estimated spatial peak specific absorption rate, 7.6 W/kg) were +0.2°C with the implant imaged “in air” and +0.3°C with the implant imaged in normal saline. Therefore, MR procedures performed with a 1.5-T (64-MHz) MR system may be performed safely in patients with any of the 13 different heart valve prostheses evaluated in this study. 相似文献
96.
97.
Unique variant of partial anomalous pulmonary venous connection with intact atrial septum 总被引:1,自引:0,他引:1
Summary Partial anomalous pulmonary venous connections (PAPVCs) are rare in association with an intact atrial septum. However, the diagnosis should be considered in patients with otherwise unexplained findings of left-to-right shunt and right heart enlargement. An unusual variant is presented, which we considered unsuitable for operative repair, based on findings at catheterization. Developmental, hemodynamic, and surgical considerations are discussed. 相似文献
98.
99.
Yihong Yang Venkata S. Mattay Daniel R. Weinberger Joseph A. Frank Jeff H. Duyn 《Journal of magnetic resonance imaging : JMRI》1997,7(2):371-375
To perform true three-dimensional activation experiments in the human brain, dedicated localized echo-volume imaging (L-EVI) methods were developed. Three-dimensional acquisition allows generation of activation maps with minimal vascular enhancement related to inflow effects. The rapid acquisition of the L-EVI (~100 msec) reduces signal instabilities caused by motion, facilitating the detection of the small intensity changes expected with brain activation. Single-shot L-EVI was performed on normal volunteers at 1.5 T, imaging a three-dimensional predefined volume (240 × 45 × 45 mm3) in the superior portion of the brain with a spatial resolution of 3.75 × 5 × 5 mm3. Increased brain coverage was achieved with a multi-volume imaging (three-shot) version, which simultaneously achieved effective suppression of signals from cerebrospinal fluid. In addition, both asymmetric spin-echo (ASE) and spin-echo (SE) versions of the technique were used to detect blood oxygenation level dependent (BOLD) signal changes in the motor cortex with a finger-tapping paradigm. Images obtained by the L-EVI sequence were qualitatively comparable to standard multislice two-dimensional echo-planar images. Both ASE and SE functional MRI (fMRI) experiments showed consistent activation in the contralateral primary sensorimotor cortex. Furthermore, significant differences in location and magnitude of activation was observed between the two methods, confirming theoretical predictions. 相似文献
100.
Abstract: Lobular carcinoma in situ (LCIS) has gone from a rare form of mammary cancer to a marker of increased risk. Treatment options have undergone a corresponding change from ipsilateral mastectomy with axillary node dissection to observation once it became clear that the majority of patients did not progress to invasive cancer. However, recent events suggest a re-evaluation of LCIS management options. It is clear that even meticulous observation may fail to detect invasive cancer before systemic spread has taken place. This fact plus the identification of breast cancer genes have brought a renewed interest in prophylactic mastectomy. At the same time pathologists feel that it is possible to identify microscopic features of LCIS pointing to an increased likelihood of developing invasive cancer. As a result physicians are being asked to better quantitate risks for individual patients. Most patients with LCIS do not need bilateral mastectomies, but we are coming closer to identifying the minority that would be better served by prophylactic surgery. 相似文献