全文获取类型
收费全文 | 18137篇 |
免费 | 1536篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 150篇 |
儿科学 | 516篇 |
妇产科学 | 513篇 |
基础医学 | 2474篇 |
口腔科学 | 598篇 |
临床医学 | 2095篇 |
内科学 | 3261篇 |
皮肤病学 | 399篇 |
神经病学 | 1694篇 |
特种医学 | 898篇 |
外科学 | 2303篇 |
综合类 | 451篇 |
一般理论 | 17篇 |
预防医学 | 1990篇 |
眼科学 | 228篇 |
药学 | 1182篇 |
1篇 | |
中国医学 | 16篇 |
肿瘤学 | 938篇 |
出版年
2022年 | 142篇 |
2021年 | 257篇 |
2020年 | 193篇 |
2019年 | 295篇 |
2018年 | 353篇 |
2017年 | 258篇 |
2016年 | 251篇 |
2015年 | 284篇 |
2014年 | 403篇 |
2013年 | 613篇 |
2012年 | 831篇 |
2011年 | 830篇 |
2010年 | 506篇 |
2009年 | 465篇 |
2008年 | 711篇 |
2007年 | 753篇 |
2006年 | 686篇 |
2005年 | 703篇 |
2004年 | 694篇 |
2003年 | 672篇 |
2002年 | 645篇 |
2001年 | 616篇 |
2000年 | 667篇 |
1999年 | 566篇 |
1998年 | 266篇 |
1997年 | 232篇 |
1996年 | 272篇 |
1995年 | 214篇 |
1994年 | 174篇 |
1993年 | 176篇 |
1992年 | 442篇 |
1991年 | 412篇 |
1990年 | 412篇 |
1989年 | 386篇 |
1988年 | 332篇 |
1987年 | 343篇 |
1986年 | 302篇 |
1985年 | 311篇 |
1984年 | 289篇 |
1983年 | 235篇 |
1982年 | 137篇 |
1980年 | 134篇 |
1979年 | 203篇 |
1978年 | 150篇 |
1976年 | 131篇 |
1975年 | 147篇 |
1974年 | 143篇 |
1973年 | 145篇 |
1972年 | 148篇 |
1971年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
We report on 4 children who experienced a syncopal episode while being treated with guanfacine without any other evident cause. Syncope appears to be an uncommon side effect of guanfacine and is probably due to drug-induced hypotension or bradycardia. 相似文献
12.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound. 相似文献
13.
R G Rees J J Payne-James C King D B Silk 《JPEN. Journal of parenteral and enteral nutrition》1988,12(5):469-472
Certain groups of patients requiring enteral nutritional support are at increased risk of regurgitation and pulmonary aspiration of feed. Positioning of enteral feeding tubes distal to the pylorus has been advocated as a method of reducing such complications. Various techniques have been suggested to achieve postpyloric siting. Reports have indicated that lengthening the tube or altering the distal end tip configuration, by varying the tip profile or by the addition of a weight, may facilitate spontaneous transpyloric passage of the tube. This prospective controlled clinical study using three new polyurethane tubes demonstrates that the frequency of spontaneous transpyloric passage of the tube is not affected by tip profile or by the addition of a weight. Indeed, with all three tube designs only about one-third had passed spontaneously through the pylorus at 24 hr. Once through the pylorus the unweighted tube stayed in position significantly longer than the weighted tubes (p less than 0.005). We suggest that in those patients requiring post-pyloric feeding, endoscopic or fluoroscopic techniques should be used to position the tubes at the time of insertion, and that an unweighted tube should be used to prolong tube usage. 相似文献
14.
Effects of eight weeks of bicycle ergometer sprint training on human muscle buffer capacity 总被引:7,自引:0,他引:7
This investigation was undertaken to determine whether human skeletal muscle buffer capacity (BCm) is affected by training. Eight untrained males participated in 8 weeks of sprint training on bicycle ergometers. Muscle biopsy samples were taken from the vastus lateralis before and at several times following an incremental bicycle ergometer test (0 min, 5 min, 15 min). These subjects were tested before (PRE) and following (POST) the training period. Seven endurance-trained cyclists (ET) were also tested for the purpose of comparing the BCm of ET to that of PRE and POST. Biopsy samples were quick-frozen in liquid nitrogen and later analyzed for lactate concentration (HLam), homogenate pH (pHm), and creatine phosphate concentration. BCm was calculated from the change in HLam and pHm observed from rest to exhaustion and was expressed as mmol X kg-1 X pH-1 (Slykes). There was no significant difference in resting HLam or resting pHm among the groups. There was a significant difference in HLam at exhaustion between PRE (21.41 +/- 1.65 mmol X kg-1), POST (25.61 +/- 2.38 mmol X kg-1), and ET (11.16 +/- 0.31 mmol X kg-1) but no significant difference in pHm at exhaustion between PRE (6.65 +/- 0.03 pH units) and POST (6.69 +/- 0.06 pH units). pHm at exhaustion for the ET group was significantly higher than the others at 6.91 +/- 0.02 pH units. A significant difference between PRE and POST BCm was found (PRE: 44.68 +/- 3.03 S1; POST: 61.04 +/- 4.11 S1) while ET BCm (47.21 +/- 7.26 S1) was not significantly different from PRE. These data indicate that muscle buffer capacity is increased with highly intense sprint training but provide no evidence to suggest that muscle buffer capacity is affected by endurance training. 相似文献
15.
A general overview of the literature concerning the development of diabetic neuropathic arthropathy is discussed. A case report is presented dealing with spontaneous fractures of the lesser metatarsal in a patient with an amputated hallux and peripheral neuropathy secondary to diabetes mellitus. 相似文献
16.
17.
K J Meador J L Thompson D W Loring A M Murro D W King B B Gallagher G P Lee J R Smith H F Flanigin 《Neurology》1991,41(6):869-872
Although there has been extensive examination of the behavioral and physiologic correlates of hippocampal theta activity in animals, the human literature consists of a single case study. We investigated the differential effects of four behavioral states on human hippocampal theta activity in 16 epilepsy surgery patients. Behavioral conditions included resting eyes closed (RC), resting eyes open (RO), eyes open with auditory word activation (AW), and eyes open with visuospatial activation (VS). Hippocampal theta activity decreased during both RO and VS compared to both RC and AW. There were reciprocal changes in delta activity. Comparisons of RO to VS and of RC to AW were nonsignificant. The results demonstrate state-specific changes in human hippocampal theta and are consistent with the animal literature that relates hippocampal theta to sensorimotor integration and forebrain volitional mechanisms. 相似文献
18.
Leslee J. Shaw Romalisa Miranda-Peats Piotr Slomka John Friedman Sean W. Hayes Daniel S. Berman Gary V. Heller Marcin Dada William E. Boden Paul Casperson Robert A. O’Rourke Ronald Schwartz William S. Weintraub David J. Maron Spencer King Koon Teo Pamela Hartigan 《Journal of nuclear cardiology》2006,13(5):685-698
Background Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after
intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical
outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial.
Methods and Results The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical
therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been
designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia
at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship
between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate
the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization
patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic
intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive
risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization
in reducing patients’ ischemic burdens.
Conclusions The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology.
We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based
management of patients with stable coronary disease.
The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research
and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained
from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data
Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon;
and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional
funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research
from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging. 相似文献
19.
20.
Robert N. Page Lee Dittrich Roy King Fouad Boulos David L. Page 《Journal of cutaneous pathology》2009,36(11):1206-1209
Originally described by Rosen in 1983, syringomatous nipple adenoma (SAN) is a tumor of disputed histogenesis, which can be problematic both diagnostically and therapeutically. 1 It is a benign primary tumor of breast epithelium with histology similar to that of the syringoma. In the current case, we describe a 40-year-old female with this lesion occurring within a supernumerary breast. This case represents, to our knowledge, the first such reported case, and represents a significant finding as its presence could lend some confusion as to whether or not this represents a benign primary process of breast or a potentially infiltrative tumor of the skin. 相似文献