全文获取类型
收费全文 | 243806篇 |
免费 | 11547篇 |
国内免费 | 407篇 |
专业分类
耳鼻咽喉 | 3194篇 |
儿科学 | 7617篇 |
妇产科学 | 5003篇 |
基础医学 | 35055篇 |
口腔科学 | 5637篇 |
临床医学 | 19369篇 |
内科学 | 53331篇 |
皮肤病学 | 6450篇 |
神经病学 | 21740篇 |
特种医学 | 7568篇 |
外国民族医学 | 106篇 |
外科学 | 30476篇 |
综合类 | 1025篇 |
一般理论 | 65篇 |
预防医学 | 21726篇 |
眼科学 | 4920篇 |
药学 | 17107篇 |
中国医学 | 723篇 |
肿瘤学 | 14648篇 |
出版年
2023年 | 1294篇 |
2022年 | 905篇 |
2021年 | 3565篇 |
2020年 | 2126篇 |
2019年 | 3983篇 |
2018年 | 7641篇 |
2017年 | 5044篇 |
2016年 | 5093篇 |
2015年 | 5644篇 |
2014年 | 5926篇 |
2013年 | 9504篇 |
2012年 | 16528篇 |
2011年 | 16447篇 |
2010年 | 8231篇 |
2009年 | 6110篇 |
2008年 | 14116篇 |
2007年 | 15122篇 |
2006年 | 13938篇 |
2005年 | 13795篇 |
2004年 | 12969篇 |
2003年 | 11830篇 |
2002年 | 11265篇 |
2001年 | 6439篇 |
2000年 | 6569篇 |
1999年 | 5819篇 |
1998年 | 976篇 |
1997年 | 805篇 |
1996年 | 779篇 |
1992年 | 3341篇 |
1991年 | 3002篇 |
1990年 | 2876篇 |
1989年 | 2620篇 |
1988年 | 2512篇 |
1987年 | 2326篇 |
1986年 | 2233篇 |
1985年 | 2028篇 |
1984年 | 1497篇 |
1983年 | 1285篇 |
1982年 | 728篇 |
1979年 | 1338篇 |
1978年 | 919篇 |
1977年 | 873篇 |
1975年 | 858篇 |
1974年 | 1053篇 |
1973年 | 1079篇 |
1972年 | 1000篇 |
1971年 | 984篇 |
1970年 | 925篇 |
1969年 | 957篇 |
1968年 | 854篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Postpartum fatigue is a normal condition that most women experience. Breastfeeding is often associated in women's minds as contributing to the feeling of overall perceived fatigue, and many women indicate that they have ceased breastfeeding because of fatigue. However, the relationship between feeding choice and perceived fatigue has never been established. Two hundred and fifty-three women participated in a study examining whether perceived fatigue differed for bottle-feeding and breastfeeding women at 3 different times during the postpartum period (2-4 days, 6 weeks, and 12 weeks postpartum). Results showed no significant differences for these 2 groups, suggesting that perceived fatigue during the postpartum period is not dependent on feeding choice. Additional analyses examining other variables with a potential effect were nonsignificant. Because perceived physical fatigue does not appear to be dependent on feeding choice, women should be prepared for the feeling of perceived fatigue during the postpartum period while at the same time be reassured that feeding choice is not correlated. 相似文献
22.
Jorge Guardado Carlos Cotrim Otília Sim?es Sofia Almeida Mário Ialá Luís Lopes Hélder Pereira Manuel Carrageta 《Revista portuguesa de cardiologia》2006,25(4):409-415
INTRODUCTION: Transesophageal echocardiography (TEE) has become increasingly useful in the study of patients with suspected pulmonary thromboembolism. OBJECTIVE: The aim of this study was to prospectively evaluate the usefulness of TEE in the study of the distal part of the left pulmonary artery (LPA) as well as the influence of this procedure on total echocardiographic exam duration. METHODOLOGY: A prospective study in two groups of consecutive patients referred for TEE with a one- year interval between evaluation of Group A: 33 patients, 17 male, mean age 54 +/- 24 years, and Group B: 42 patients, 20 male, mean age 48 +/- 27 years (p = NS). The procedure was considered long when it took more than 3 min to evaluate the distal part of the LPA. RESULTS: In group A we were able to visualize the distal part of the LPA in 24 patients (73%) without significant prolongation of total exam duration in 16 patients (48% of group A). In one of the patients with suspected pulmonary thromboembolism thrombi were only observed in the distal part of the LPA. In group B we were able to visualize the distal part of the LPA in 36 patients (86%) without significant prolongation of total exam duration in 26 patients (61% of group B). CONCLUSIONS: 1. Visualization of the distal part of the LPA was possible in more patients, and with TEE time prolongation in less patients, in group B. These differences can be accounted for by the training of the operator in this technique. 2. The importance of visualization of this part of the LPA in guiding treatment in the subset of patients with pulmonary thromboembolism confirms the usefulness of this specific procedure. 相似文献
23.
Anne-Catherine Bachoud-Lévi Philippe Hantraye Marc Peschanski 《Movement disorders》2002,17(3):439-444
Intrastriatal transplantation of striatal neuroblasts from human fetuses is a promising approach for treatment of Huntington's disease, on the basis of many experimental animal studies and, most recently, pilot clinical trials. Technically, several issues remain to be resolved (e.g., the precise site of dissection of the fetal tissue; the number and location of the fetal striatal implants; or the use of immunosuppressive therapy), and await larger-scale trials and purposely designed protocols. Further clinical data must also be obtained, and preliminary promising results must be replicated in a patient group large enough to provide conclusive results. It is important to establish (1) the amount of clinical benefit provided to the patient by the grafted cells; (2) the anticipated duration of clinical benefits; and (3) the secondary rate of decline after the benefit of the graft has been overbalanced. Evaluation of these parameters will require very long-term follow-up of the patients involved, over several years after grafting, before the technique can eventually be proposed widely to patients. 相似文献
24.
The degree of metabolic acidosis at birth has been calculated in cord artery and vein samples from 21 term fetuses with cord artery pH less than 7.20. The aim of the study was to compare base deficit values calculated from either Siggaard-Andersen alignment nomogram (BD blood) or the Acid-Base chart (BD extra cellular fluid, BDecf). BDblood was found to be consistently higher in the cord artery as compared with BDecf, 13.2 +/- 3.5 and 9.9 +/- 2.9 mmol/l (Mean +/- SD), respectively. A significant correlation was found between cord artery PCO2 and BDblood whereas BDecf appeared unaffected by PCO2. In cases with cord entanglement BDecf a-v differences were increased to 3.4 +/- 2.3 mmol/l as compared with the small a-v difference noted in acidotic cases without cord entanglement, 1.1 +/- 1.25 mmol/l. It is speculated that with acutely emerging, intermittent asphyxia due to cord compression, a cord artery and vein difference in metabolic acidosis may exist and where the vein captures the basal level and the artery the acute changes. It is concluded that BDecf in both cord artery and vein add valuable information on the mechanisms behind metabolic acidosis. 相似文献
25.
26.
27.
28.
Severe herpetic keratitis. I: Prevalence of visual impairment in a clinic population. 总被引:1,自引:1,他引:0 下载免费PDF全文
We report a prevalence study of the best visual acuity in the affected eye of 100 selected patients with herpetic keratitis seen during a two-year period. Sixty-two patients retained an acuity of 6/9 or better without requiring penetrating keratoplasty (PK). The prevalence of reduced visual acuity severe enough to warrant PK was 33%. Patients requiring PK for whom full clinical records were available suffered a mean of 6.8 episodes of keratitis. In this group of patients the vision of 18 fell from 6/6 to 6/60 over a mean period of 8.5 years. Once visual acuity was permanently reduced to 6/12, 78% of patients proceeded to lose vision to 6/60. Unilateral visual impairment occurs in at least a third of patients with severe herpetic keratitis. Once vision falls permanently to 6/12, the long-term prognosis for vision appears to be poor. 相似文献
29.
30.
J G Classé 《Journal of the American Optometric Association》1986,57(1):66-71
In establishing the liability of optometrists for negligence the courts have applied the same standard of care that is imposed upon other health care professionals, holding that optometrists must employ the minimum degree of skill, care and learning that is ordinarily exhibited by members of the profession who are in good standing. The leading cases establishing this standard have involved glaucoma, retinal detachment, and intraocular tumors. Optometrists have also been held liable under product liability law for injuries caused by ophthalmic lenses, which illustrates the trend toward strict liability. Other cases have involved the doctrine of informed consent. 相似文献