全文获取类型
收费全文 | 36575篇 |
免费 | 2371篇 |
国内免费 | 446篇 |
专业分类
耳鼻咽喉 | 718篇 |
儿科学 | 445篇 |
妇产科学 | 632篇 |
基础医学 | 5897篇 |
口腔科学 | 647篇 |
临床医学 | 3051篇 |
内科学 | 6846篇 |
皮肤病学 | 1574篇 |
神经病学 | 2603篇 |
特种医学 | 2662篇 |
外科学 | 5184篇 |
综合类 | 205篇 |
一般理论 | 21篇 |
预防医学 | 1372篇 |
眼科学 | 765篇 |
药学 | 3385篇 |
中国医学 | 520篇 |
肿瘤学 | 2865篇 |
出版年
2023年 | 285篇 |
2022年 | 921篇 |
2021年 | 1411篇 |
2020年 | 676篇 |
2019年 | 1024篇 |
2018年 | 1186篇 |
2017年 | 936篇 |
2016年 | 1421篇 |
2015年 | 1998篇 |
2014年 | 2249篇 |
2013年 | 2482篇 |
2012年 | 3634篇 |
2011年 | 3401篇 |
2010年 | 2169篇 |
2009年 | 1676篇 |
2008年 | 2218篇 |
2007年 | 2071篇 |
2006年 | 1880篇 |
2005年 | 1698篇 |
2004年 | 1319篇 |
2003年 | 1128篇 |
2002年 | 965篇 |
2001年 | 368篇 |
2000年 | 343篇 |
1999年 | 274篇 |
1998年 | 150篇 |
1997年 | 118篇 |
1996年 | 97篇 |
1995年 | 77篇 |
1994年 | 74篇 |
1993年 | 61篇 |
1992年 | 86篇 |
1991年 | 95篇 |
1990年 | 72篇 |
1989年 | 54篇 |
1988年 | 66篇 |
1987年 | 53篇 |
1986年 | 65篇 |
1985年 | 50篇 |
1984年 | 52篇 |
1983年 | 65篇 |
1982年 | 36篇 |
1981年 | 29篇 |
1979年 | 35篇 |
1978年 | 34篇 |
1977年 | 24篇 |
1976年 | 24篇 |
1973年 | 30篇 |
1972年 | 23篇 |
1971年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Holly A Taylor Erin L McDonald Margaret Moon Mark T Hughes & Joseph A Carrese 《Medical education》2009,43(10):952-959
Context Previous research on ethical issues encountered by medical professionals in training and practice have presented the thematic content of the cases they encounter rather than the activities in which clinicians engage and in which they most often encounter ethical issues. We conducted a direct observation study of paediatrics residents and their preceptors seeing patients in an out‐patient general paediatrics clinic. Our objectives were to describe the everyday ethics‐related issues paediatrics residents encounter as they interact with patients. Our ultimate goal is to use this knowledge to enhance current efforts to teach ethics to paediatrics residents. Methods The study team directly observed paediatrics residents discussing patients with their faculty preceptors (19 half‐day sessions, 76 hours) in an out‐patient general paediatrics clinic located in an urban academic medical centre. Each interaction between resident and preceptor about a single patient was considered a case for further analysis. Results A total of 247 cases were recorded. Forty‐one of the cases were coded as having ethics‐related content. A constant comparative method of qualitative data analysis revealed that residents were most likely to encounter ethical issues when engaged in the following activities: (i) maintaining a therapeutic alliance with the caregiver (e.g. the parent); (ii) prioritising patient or family needs; (iii) adjusting to the power embodied by the role of doctors, and (iv) distinguishing suboptimal care from abuse or neglect. In addition, our findings indicate that it is through their efforts to maintain the therapeutic alliance with the caregivers of their patients that residents engage in and integrate three processes: developing their medical knowledge; adhering to professional norms, and balancing the power inherent in the doctor’s role with their responsibility to serve the patient’s interests. Conclusions Medical faculty tasked with teaching ethics to paediatrics residents can utilise the results of this project to better target and enhance their ethics education efforts directed at residents in the out‐patient setting. Future research could further examine and test these findings in other clinical settings (e.g. adult general medicine). 相似文献
102.
103.
Sungil Jang Eun Jung Bak Minyoung Kim Jin Moon Kim Won-Yoon Chung Jeong-Heon Cha Yun-Jung Yoo 《Phytotherapy research : PTR》2010,24(7):964-968
To evaluate the inhibitory activity of wogonin against lipopolysaccharide (LPS)-induced bone resorption, we investigated the effect of wogonin on osteoclastogenesis induced by LPS. Wogonin inhibited LPS-induced osteoclastogenesis in co-cultures of mouse calvaria-derived osteoblasts and bone marrow-derived pre-osteoclasts. Wogonin also suppressed osteoclastogenesis in LPS-injected mouse calvaria. In osteoblasts, the upregulation of receptor activator of nuclear factor-κB (RANKL) expression and the downregulation of osteoprotegerin (OPG) expression by LPS were inhibited by wogonin. Wogonin and NS-398, a COX-2 inhibitor, suppressed LPS-stimulated PGE2 production in osteoblasts. NS-398 inhibited the effect of LPS on RANKL and OPG expression in osteoblasts. These results suggest that wogonin acts as an inhibitor of LPS-induced osteoclastogenesis through downregulation of RANKL and upregulation of OPG expression via blockage of PGE2 production. Based on these results, wogonin has potential for use as a therapeutic agent in bacteria-induced bone resorption. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
104.
Christopher L. Hansen Richard A. Goldstein Olakunle O. Akinboboye Daniel S. Berman Elias H. Botvinick Keith B. Churchwell C. David Cooke James R. Corbett S. James Cullom Seth T. Dahlberg Regina S. Druz Edward P. Ficaro James R. Galt Ravi K. Garg Guido Germano Gary V. Heller Milena J. Henzlova Mark C. Hyun Lynne L. Johnson April Mann Benjamin D. McCallister Robert A. Quaife Terrence D. Ruddy Senthil N. Sundaram Raymond Taillefer R. Parker Ward John J. Mahmarian 《Journal of nuclear cardiology》2007,14(6):e39-e60
105.
Kyoung-Ah Kim Min-Jung Kim Ji-Young Park Ji-Hong Shon Young-Ran Yoon Sang-Seop Lee Kwang-Hyeon Liu Jin-Ho Chun Myung-Ho Hyun Jae-Gook Shin 《Drug metabolism and disposition》2003,31(10):1227-1234
The stereoselective metabolism of lansoprazole enantiomers was evaluated by incubation of human liver microsomes and cDNA-expressed cytochrome p450 (p450) enzymes to understand and predict their stereoselective disposition in humans in vivo. The intrinsic clearances (Clint) of the formation of both hydroxy and sulfone metabolites from S-lansoprazole were 4.9- and 2.4-fold higher than those from the R-form, respectively. The sums of formation Clint of both metabolites were 13.5 and 57.3 microl/min/mg protein for R- and S-lansoprazole, respectively, suggesting that S-lansoprazole would be cleared more rapidly than the R-form. The p450 isoform selective inhibition study in liver microsomes, and the incubation study of cDNA-expressed enzymes, demonstrated that the stereoselective sulfoxidation is mediated by CYP3A4 and that the hydroxylation is mediated by CYP2C9 and CYP3A4 as well as by CYP2C19. Total Clint values of hydroxy and sulfone metabolite formation catalyzed by all these p450 enzymes were consistently higher for S-lansoprazole than for the R-form. The CYP3A4 produced the greatest difference of Clint between S- and R-enantiomers, mainly due to a difference of sulfoxidation metabolism (Clint 76.5 versus 10.8 microl/min/nmol of p450, respectively), whereas CYP2C19-catalyzed hydroxylation resulted in a minor difference of Clint between S- and R-enantiomers (179.6 versus 143.3 microl/min/nmol of p450, respectively). However, the affinity of CYP2C19 on hydroxylation was 5.7-fold higher for S-enantiomer than for the R-form (Km 2.3 versus 13.1 microM), suggesting that the role of CYP2C19 on stereoselective hydroxylation would be more prominent at concentrations around the usual therapeutic level. These findings suggest that both CYP2C19 and CYP3A4 are major enzymes contributing to the stereoselective disposition of lansoprazole, but stereoselective hydroxylation of lansoprazole enantiomers is mainly influenced by CYP2C19, especially at the usual therapeutic doses. 相似文献
106.
Hy De Lee Euy Young Soh Hoon Sang Chi Byong Ro Kim Kyong Sik Lee Kyung Soon Song Hyun Joo Jung 《Surgery today》1990,20(2):180-185
The relationship between primary tumor proliferative activity and clinical and pathologic characteristics was analyzed in
relation to menopausal status in 32 patients with malignant or benign breast disease. The thymidine labeling index (TLI) showed
significantly higher median values in the cancer patients (3.48 per cent) than in the patients with benign diseases (1.02
per cent). TLI was not significantly affected by delayed incubation at room temperature for about 1 hour. In the breast cancer
patients, TLI did not significantly correlate to tumor size, the presence of axillary lymph node metastasis or pathologic
nuclear grading. The only significant difference was limited to the breast cancer patients without axillary lymph node metastasis
in relation to menopausal status; the TLI in the premenopausal patients (5.10 per cent) was significantly higher (p<0.05)
than that in the postmenopausal patients (2.28 per cent). These data thus suggest that among premenopausal patients without
axillary lymph node metastasis, those with a high TLI could be potential candidates for adjuvant chemotherapy. 相似文献
107.
The sperm penetration assay is an expensive, time-consuming test to assess male fertility in vitro. Although some investigators are enthusiastic in its application, others feel that it is not sensitive or specific enough to be used as part of the routine infertility evaluation. Indeed, this bioassay is not a faithful reproduction of in vivo conditions. However, if the SPA is abnormal, it is unlikely that sperm will fertilize a human ovum in vivo. Conversely, a normal SPA does not guarantee successful in vivo fertilization. No bioassay can be absolute in its predictive value, but false-negative results must be kept to a minimum for this bioassay to be of any clinical significance. Each laboratory performing the SPA should optimize the assay for sensitivity, reproducibility, and minimization of false-negative results and then establish normal and abnormal ranges of its own. If the limitations of the SPA are kept in mind, and if we employ it very selectively, it may still be useful. 相似文献
108.
W K Moon M H Han I O Kim M W Sung K H Chang S W Choo M C Han 《AJNR. American journal of neuroradiology》1995,16(4):997
We report a case of congenital fistula from ectopic accessory parotid gland to the cheek demonstrated by CT sialography and CT fistulography. The right parotid gland was abnormally located lateral to masseter muscle. The fistula was arising from an ectopic accessory parotid gland with ectopic duct positioned anterior to masseter muscle. CT sialography and CT fistulography were very helpful in the diagnosis and surgical planning. 相似文献
109.
Shi Yong Ryu Chong-Kyo Lee Chong Ock Lee Hae Soo Kim Ok Pyo Zee 《Archives of pharmacal research》1992,15(3):242-245
Two triterpenes 1 and 2 with antiviral activity againstHerpes simplex virus type 1in vitro were isolated fromPrunella vulgaris. Each compound caused a significant reduction in viral cytopathic effect whenvero cells were exposed to them for 72 hours after viral challenge. They were identified asbetulinic acid(1) and 2α, 3α-dihydroxyurs-12-en-28-oic acid(2) on the basis of their spectroscopic properties. The antiviral activity of them was estimated as EC50=30 μg/ml(1) and 8 μg/ml(2), respectively by plaque reduction assay. 相似文献
110.
Kyung Cheon Kim Kwang Jin Rhee Hyun Dae Shin Young Mo Kim 《Knee surgery, sports traumatology, arthroscopy》2007,15(12):1478-1481
Calcific tendinitis is a common condition with characteristic clinical and radiological findings. Although we do not know
which condition initiated the pathologic cascade, we present a rare case of calcific tendinitis of the long head of the biceps
brachii at its origin, associated with a SLAP lesion. The calcium deposit was removed and the SLAP lesion was repaired with
a suture anchor arthroscopically. 相似文献