全文获取类型
收费全文 | 46556篇 |
免费 | 4160篇 |
国内免费 | 1201篇 |
专业分类
耳鼻咽喉 | 372篇 |
儿科学 | 1306篇 |
妇产科学 | 707篇 |
基础医学 | 5822篇 |
口腔科学 | 669篇 |
临床医学 | 5526篇 |
内科学 | 8804篇 |
皮肤病学 | 543篇 |
神经病学 | 3380篇 |
特种医学 | 1649篇 |
外国民族医学 | 6篇 |
外科学 | 6871篇 |
综合类 | 3446篇 |
现状与发展 | 4篇 |
一般理论 | 28篇 |
预防医学 | 3564篇 |
眼科学 | 818篇 |
药学 | 3838篇 |
18篇 | |
中国医学 | 1008篇 |
肿瘤学 | 3538篇 |
出版年
2024年 | 98篇 |
2023年 | 545篇 |
2022年 | 1159篇 |
2021年 | 1994篇 |
2020年 | 1261篇 |
2019年 | 1459篇 |
2018年 | 1691篇 |
2017年 | 1342篇 |
2016年 | 1284篇 |
2015年 | 1670篇 |
2014年 | 2138篇 |
2013年 | 2337篇 |
2012年 | 3543篇 |
2011年 | 3612篇 |
2010年 | 2203篇 |
2009年 | 1803篇 |
2008年 | 2679篇 |
2007年 | 2619篇 |
2006年 | 2496篇 |
2005年 | 2346篇 |
2004年 | 2067篇 |
2003年 | 1920篇 |
2002年 | 1836篇 |
2001年 | 716篇 |
2000年 | 544篇 |
1999年 | 583篇 |
1998年 | 452篇 |
1997年 | 411篇 |
1996年 | 309篇 |
1995年 | 277篇 |
1994年 | 296篇 |
1993年 | 229篇 |
1992年 | 308篇 |
1991年 | 248篇 |
1990年 | 241篇 |
1989年 | 208篇 |
1988年 | 226篇 |
1987年 | 203篇 |
1986年 | 204篇 |
1985年 | 185篇 |
1984年 | 197篇 |
1983年 | 147篇 |
1982年 | 146篇 |
1981年 | 147篇 |
1980年 | 131篇 |
1979年 | 146篇 |
1978年 | 112篇 |
1977年 | 98篇 |
1973年 | 107篇 |
1971年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
乳腺占位病变的高场强MRI诊断价值 总被引:1,自引:1,他引:0
目的 :总结乳腺良恶性占位病变在高场强MRI的影像表现 ,评价高场强MRI对乳腺良恶性病变的诊断价值。方法 :搜集1996~ 2 0 0 4年间经手术病理证实的 4 3例乳腺良恶性占位病变的MRI资料 ,分析其影像表现。结果 :典型乳腺良、恶性病变 ,高场强MR平扫即能准确诊断 ,而部分非典型良、恶性病灶 ,增强扫描形态、信号变化也有一定的重叠。结论 :MRI技术能够充分显示病变形态及与周围组织结构之间的关系 ,是建议活检或预防性手术的最有力的依据。但是 ,MRI平扫、增强技术对乳腺非典型病变 ,仍然有局限性 相似文献
92.
93.
94.
OBJECTIVE: To study the value of serum progesterone in selecting the candidate patients with ectopic pregnancy (EP) for methotrexate (MTX) treatment and in monitoring the effect of the treatment. METHODS: Thirty-seven EP patients who were given single-dose intramuscular injection with 50 mg/m2 MTX were divided into success and failure groups according to the effect of the treatment. The serum progesterone concentrations in these patients were measured and compared between the 2 groups, and the receiver-operator curves (ROC) were used to determine the critical serum progesterone levels for assessing the effect of MTX treatment. The time consumed respectively by serum progesterone and beta-human chorionic gonadotrophin (beta-hCG) decreasing to below normal level was also compared. RESULTS: The serum progesterone concentrations of the success group (7.93+/-2.02 ng/ml) were significantly lower than those of the failure group (14.53+/-1.72 ng/ml, P<0.05). The recommended critical level for assessing the effect of MTX treatment for EP patients was 11 ng/ml according to the ROC, and the time for serum progesterone decreasing to below normal level was significantly less than that for beta-hCG. CONCLUSION: Serum progesterone can be used as an index for selecting candidate EP patients for MTX treatment, and also as a good indicator for assessing the therapeutic effect after treatment. 相似文献
95.
Guochuan Tsai Hsien-Yuan Lane Pinchen Yang Mian-Yoon Chong Nicholas Lange 《Neuropsychopharmacology》2004,55(5):452-456
BACKGROUND: Hypofunction of N-methyl-D-aspartate glutamate receptor had been implicated in the pathophysiology of schizophrenia. Treatment with D-serine or glycine, endogenous full agonists of the glycine site of N-methyl-D-aspartate receptor, or D-cycloserine, a partial agonist, improve the symptoms of schizophrenia. N-methylglycine (sarcosine) is an endogenous antagonist of glycine transporter-1, which potentiates glycine's action on N-methyl-D-aspartate glycine site and can have beneficial effects on schizophrenia. METHODS: Thirty-eight schizophrenic patients were enrolled in a 6-week double-blind, placebo-controlled trial of sarcosine (2 g/d), which was added to their stable antipsychotic regimens. Twenty of them received risperidone. Measures of clinical efficacy and side effects were determined every other week. RESULTS: Patient who received sarcosine treatment revealed significant improvements in their positive, negative, cognitive, and general psychiatric symptoms. Similar therapeutic effects were observed when only risperidone-treated patients were analyzed. Sarcosine was well-tolerated, and no significant side effect was noted. CONCLUSIONS: Sarcosine treatment can benefit schizophrenic patients treated by antipsychotics including risperidone. The significant improvement with the sarcosine further supports the hypothesis of N-methyl-D-aspartate receptor hypofunction in schizophrenia. Glycine transporter-1 is a novel target for the pharmacotherapy to enhance N-methyl-D-aspartate function. 相似文献
96.
Shafi Mussa Tash Prior Nicholas Alp Kathryn Wood Keith M Channon David P Taggart 《European journal of cardio-thoracic surgery》2004,26(5):988-994
OBJECTIVE: Radial arteries are increasingly used as conduits for coronary artery bypass grafts, but perioperative graft vasospasm remains a concern. In vitro testing has demonstrated the efficacy of phenoxybenzamine and verapamil/nitroglycerin as topical antispasmodic agents, but their duration of action in vivo is unknown. Using an in vivo mouse model, we measured their duration of action in functioning vascular grafts, and compared this to their in vitro duration of action in ungrafted vascular segments. METHODS: Two millimetre mouse aortic segments (C57/BL6) were incubated with phenoxybenzamine, verapamil/nitroglycerin, or buffer (controls) for 15 min in organ chambers. Isometric tension responses to phenylephrine and prostaglandin F2alpha were measured at 0, 2, 6 and 12 h post-incubation. In parallel, 36 murine infrarenal aortic interposition grafts (2 mm) were performed. Twelve grafts were pre-treated (15 min) with phenoxybenzamine, 12 with verapamil/nitroglycerin and 12 remained untreated (controls). Isometric tension responses to the same agonists were measured in grafts harvested 2, 6, 13 and 23 h after surgery. RESULTS: Phenoxybenzamine prevented alpha-adrenergic vasoconstriction for up to 16 h in vivo (grafts), and 12h in vitro (ungrafted segments). Verapamil/nitroglycerin was effective for at least 2 h in vitro, but did not prevent vasoconstriction after 2 h in vivo. CONCLUSIONS: The mouse model appears to be a useful technique for assessing the pharmacological properties of antispasmodic agents in vivo. Phenoxybenzamine has an extended action in arterial grafts in vivo. Verapamil/nitroglycerin is short-lived in vivo but lasts longer in vitro. Measurements of antispasmodic duration of action in vitro should be interpreted with caution. 相似文献
97.
98.
Cesar G. Victora Nubia Muoz Nicholas E. Day Lucio B. Barcelos Debora A. Peccin Noris M. Braga 《International journal of cancer. Journal international du cancer》1987,39(6):710-716
There is a cluster of high-incidence areas of oesophageal cancer in south-eastern South America, including Southern Brazil, Uruguay and parts of Argentina. The present case-control study investigated the hypothesis that this may be due to the drinking of maté, a traditional beverage drunk at a very high temperature, and also studied the role of other known risk factors such as alcohol and tobacco. Cases (171) and age- and sex-matched controls (342) were recruited from hospitals in the State of Rio Grande do Sul in Southern Brazil. The crude odds ratio for daily maté drinkers was 1.92 relative to those drinking less frequently than daily (p = 0.006). Other risk factors included the drinking of cachaça (a sugar cane spirit), smoking, rural residence, low fruit consumption and high intake of meats. After adjustment for these variables through conditional logistic regression, the odds ratio associated with daily maté drinking was reduced to 1.47 (90% CI = 0.87 - 2.50). Although the study failed to provide evidence of a strong association between maté and oesophageal cancer, the cluster of high rates could be explained by relative risks of the magnitude observed. This is due to the fact that approximately 70% of adult males and 50% of females are daily drinkers. In addition, this study revealed that alcohol, tobacco smoking and rural residence are the main risk factors for oesophageal cancer in this population and the fruit consumption confers some degree of protection. 相似文献
99.
100.
R Long 《中华耳鼻咽喉科杂志》1989,24(1):34-6, 63
One hundred and seventy patients with nasal polyps were studied. According to the history, skin tests with inhalant allergens, determination of serum nasal secretion and polyp fluid IgE, and X-ray films of nasal sinuses, it was suggested that 93.5% of them might have complicated with allergic diseases, 87.7% with sinusitis. A relationship between local IgE production and the eosinophil infiltration of polyps existed. This study suggests that allergic process acting locally on the mucous membrane of the nose is the etiologic factor and bacterial allergy probably contributes to the development of nasal polyps. In order to prevent the recurrence after polypectomy, antiallergic management combined with antibiotics and drainage of infected sinuses may be necessary in most cases. 相似文献