全文获取类型
收费全文 | 687774篇 |
免费 | 51867篇 |
国内免费 | 24918篇 |
专业分类
耳鼻咽喉 | 8013篇 |
儿科学 | 11478篇 |
妇产科学 | 14652篇 |
基础医学 | 90545篇 |
口腔科学 | 16778篇 |
临床医学 | 73998篇 |
内科学 | 125074篇 |
皮肤病学 | 11318篇 |
神经病学 | 44601篇 |
特种医学 | 25350篇 |
外国民族医学 | 295篇 |
外科学 | 91647篇 |
综合类 | 58391篇 |
现状与发展 | 77篇 |
一般理论 | 82篇 |
预防医学 | 36314篇 |
眼科学 | 18701篇 |
药学 | 62329篇 |
335篇 | |
中国医学 | 19422篇 |
肿瘤学 | 55159篇 |
出版年
2023年 | 5601篇 |
2022年 | 14094篇 |
2021年 | 18764篇 |
2020年 | 13546篇 |
2019年 | 13352篇 |
2018年 | 15483篇 |
2017年 | 13018篇 |
2016年 | 12488篇 |
2015年 | 17950篇 |
2014年 | 22927篇 |
2013年 | 22189篇 |
2012年 | 32054篇 |
2011年 | 35213篇 |
2010年 | 21634篇 |
2009年 | 17716篇 |
2008年 | 25809篇 |
2007年 | 26547篇 |
2006年 | 26662篇 |
2005年 | 25572篇 |
2004年 | 19127篇 |
2003年 | 17944篇 |
2002年 | 16348篇 |
2001年 | 34273篇 |
2000年 | 35743篇 |
1999年 | 31624篇 |
1998年 | 10259篇 |
1997年 | 9504篇 |
1996年 | 8027篇 |
1995年 | 7303篇 |
1994年 | 6232篇 |
1993年 | 4851篇 |
1992年 | 18428篇 |
1991年 | 16760篇 |
1990年 | 15903篇 |
1989年 | 15449篇 |
1988年 | 13799篇 |
1987年 | 13115篇 |
1986年 | 11942篇 |
1985年 | 10993篇 |
1984年 | 7292篇 |
1983年 | 5863篇 |
1982年 | 2896篇 |
1979年 | 5644篇 |
1978年 | 3409篇 |
1977年 | 3038篇 |
1975年 | 2701篇 |
1974年 | 3148篇 |
1973年 | 2933篇 |
1972年 | 2898篇 |
1971年 | 2814篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Xiaoguang Chen Yi Li Lei Wang Mark Katakowski Lijie Zhang Jieli Chen Yongxian Xu Subhash C. Gautam Michael Chopp 《Neuropathology》2002,22(4):275-279
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain. 相似文献
82.
T Uno M Takamatsu Y Inoue Y Kawahata K Iuchi G Tsukamoto 《Journal of medicinal chemistry》1987,30(12):2163-2169
A series of 6-fluoro- and 6,8-difluoro-7-(azole substituted)-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids were prepared. Structure-activity relationship studies indicated that the antibacterial potency was better when the 6,8-substituents were fluorine atoms and the 7-substituent was either 1-imidazolyl, 20, or 4-methyl-1-imidazolyl, 25. From the results of studies on pharmacokinetic profile and toxicity, 20 and 25 were found to possess excellent antibacterial activities and to show high blood levels after oral administration to mice with low toxicity. 相似文献
83.
84.
Y Abiko K Ichihara K Sakai H Sashida T Ishibashi 《Methods and findings in experimental and clinical pharmacology》1986,8(5):271-278
This paper describes a method by which antianginal drugs can be evaluated in the dog heart in situ. Myocardial pH was measured continuously by a micro glass pH electrode inserted in the left ventricular endocardial layers of the dog anesthetized with pentobarbital. Occlusion of the left anterior descending coronary artery (LAD) decreased myocardial pH, and release of the LAD restored the pH. The myocardial acidosis induced by ischemia was metabolic in nature and accompanied by a decrease in the levels of adenosine triphosphate and creatine phosphate and an increase in the levels of lactate in the myocardium. Drugs were injected intravenously 30 min after incomplete (partial) occlusion ot the LAD, lasting until 60 min after drug injection. Propranolol, atenolol, and sotalol markedly attenuated the myocardial pH that had been decreased by LAD occlusion. Nitroglycerin, diltiazem, and nicorandil also attenuated the pH, but these drugs were less active in attenuating myocardial acidosis. Dipyridamole, nifedipine, and beta-2 adrenoceptor antagonists were least active in this regard. It is concluded that myocardial pH can be used as an indicator of myocardial regional ischemia and utilized for evaluation of antianginal drugs. 相似文献
85.
OBJECTIVE: To investigate the characteristics of the early stage treponema pallidum infected tissue in ear, nose, oropharynx and larynx and to raise relevance ratio of syphilis in nose and oropharynx and enhance doctor's self-protection awareness. METHODS: The histopathologic characteristics were studied by using HE staining, Warthin-Starry (W-S) staining was adopted to examine the treponema pallidum(TP) in lesion issue and its exudates smear for 12 cases biopsy tissues of suspicious syphilis. The diagnosis was confirmed by venereal disease research laboratory (VDRL), rapid plasma reagin circle test(RPR), treponema pallidum hemagglutination test(TPHA) and fluorescent treponemal antibody-absorption test (FTA-ABS). Treat with curing syphilis methods which published by nation. RESULTS: In the 12 cases mucous membrane specimen, the squamous epithelium proliferated, neutrophilic granulocyte infiltrated, within inherent membrane generous plasmacyte and lymphocyte infiltrated. W-S staining: plenty of treponema pallidum were found inside mucous membrane epithelium and exudate smear. Serology examination: 11 cases VDRL(++++), 7 cases RPR (+), 11 cases TPHA(+), 1 case FTA-ABS(+). After systemic treatment, 11 cases are clinically recovered. All patients serology become negative. CONCLUSION: W-S staining method can directly demonstrate histopathologic characteristics in early syphilis, in intrinsic membrane numerous plasmacyte infiltration. Combining with specific syphilis serology examination could increase diagnosis rate of syphilis in nose and oropharynx. 相似文献
86.
Intracranial pathology is a common and important complication in extremely low birth weight babies. Lenticulostriate vasculopathy (LSV) is an abnormal finding on cranial ultrasounds of sick babies and has been associated with congenital infection, chromosomal aberration and twin-to-twin transfusion. We describe a previously unreported situation of LSV being detected in both donor and recipient twin. This pair of monochorionic, diamniotic twins was admitted to the Neonatal Intensive Care Unit at 28 weeks of gestation. The mother underwent an emergency caesarean section because ultrasound and Doppler studies showed stage III twin-to-twin transfusion syndrome. The first twin weighed 998 g and second twin weighed 600 g. The first twin had an uneventful stay, whereas the second twin needed prolonged continuous positive airway pressure and indomethacin for patent ductus arteriosus. Both of them developed LSV. The clinical significance of this condition on the neuro-developmental outcome of a neonate has not yet been fully determined. 相似文献
87.
Y. Graif A. Goldberg R. Tamir D. Vigiser S. Melamed 《Clinical and experimental allergy》2006,36(12):1532-1537
BACKGROUND: In allergic conditions, the degree of skin test reactivity does not always correlate with the severity of clinical symptoms. Additional factors may contribute to the reported symptom severity. OBJECTIVES: To investigate the association between the magnitude of the skin prick test (SPT) response and the reported symptom severity in patients with allergic rhinitis and the possible modifying role of psychological factors. METHODS: One hundred four patients with allergic rhinitis and 23 with non-allergic rhinitis, classified according to their SPT response to 19 aeroallergens, were asked to rate the severity of five symptoms and to indicate whether their symptoms intensified on exposure to five common aeroallergens. They also completed a psychological questionnaire. Results Reported symptom severity of allergic rhinitis did not correlate with weal size for any of the aeroallergens tested or with the number of positive responses on SPT. It was not related to patient age, sex, or education. The reported symptoms severity correlated positively (0.29, P < 0.01) with reported symptom intensification on exposure to allergens. Moreover, both outcomes were positively associated with the psychological factors of hypochondriasis (0.20, P < 0.05 and 0.18, P < 0.05, respectively), and somatic awareness (0.24, P < 0.05 and 0.33, P < 0.01, respectively), but not with neuroticism. CONCLUSIONS: The severity of symptoms experienced by patients with allergic rhinitis is apparently not related to the magnitude of SPT response, but rather to psychological factors of hypochondriasis and somatic awareness. Physicians should be aware of the contribution of psychological factors to patient perceptions of the intensity of symptoms and of the intensification of symptoms on their exposure to allergens. 相似文献
88.
89.
90.