全文获取类型
收费全文 | 74737篇 |
免费 | 6369篇 |
国内免费 | 4005篇 |
专业分类
耳鼻咽喉 | 651篇 |
儿科学 | 1228篇 |
妇产科学 | 1135篇 |
基础医学 | 10136篇 |
口腔科学 | 1619篇 |
临床医学 | 8523篇 |
内科学 | 12896篇 |
皮肤病学 | 1028篇 |
神经病学 | 5386篇 |
特种医学 | 2519篇 |
外国民族医学 | 19篇 |
外科学 | 8929篇 |
综合类 | 9062篇 |
现状与发展 | 5篇 |
一般理论 | 13篇 |
预防医学 | 4525篇 |
眼科学 | 1866篇 |
药学 | 7240篇 |
31篇 | |
中国医学 | 2244篇 |
肿瘤学 | 6056篇 |
出版年
2024年 | 146篇 |
2023年 | 767篇 |
2022年 | 1934篇 |
2021年 | 2604篇 |
2020年 | 1830篇 |
2019年 | 1911篇 |
2018年 | 2221篇 |
2017年 | 1874篇 |
2016年 | 1786篇 |
2015年 | 2506篇 |
2014年 | 3137篇 |
2013年 | 3135篇 |
2012年 | 4540篇 |
2011年 | 4767篇 |
2010年 | 2890篇 |
2009年 | 2388篇 |
2008年 | 3506篇 |
2007年 | 3656篇 |
2006年 | 3409篇 |
2005年 | 3228篇 |
2004年 | 2409篇 |
2003年 | 2289篇 |
2002年 | 1942篇 |
2001年 | 3329篇 |
2000年 | 3255篇 |
1999年 | 2998篇 |
1998年 | 1314篇 |
1997年 | 1156篇 |
1996年 | 839篇 |
1995年 | 753篇 |
1994年 | 650篇 |
1993年 | 516篇 |
1992年 | 1355篇 |
1991年 | 1186篇 |
1990年 | 1048篇 |
1989年 | 1097篇 |
1988年 | 1002篇 |
1987年 | 912篇 |
1986年 | 838篇 |
1985年 | 722篇 |
1984年 | 442篇 |
1983年 | 391篇 |
1982年 | 225篇 |
1981年 | 189篇 |
1980年 | 145篇 |
1979年 | 243篇 |
1978年 | 103篇 |
1974年 | 101篇 |
1973年 | 109篇 |
1971年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Tang Su-en唐素恩 Kang Ying-qu康映蕖Departments of Pathology Obstetrics Gynecology First Hospital. Beijing Medical University Beijing. 《中华医学杂志(英文版)》1986,99(6):464-469
Eight cases of malignant and 12 0f benign Bren-
ner tumor are reported, patient ages ranged 31
69 and 39-53 years. The malignant tumor was
bilateral in 6 0f 8 cases, and the benign in l of 12.
The greatest diameter of the malignant tumors
averaged around 11 cm, and the benign 10. Six of
the malignant Brenner tumor patients died, one was
lost to follow up, and one survived for 10 years.
Pathologic and microscopic findings were pre-
sented in some detail. Based on the analysis of the
association between the histologic features and type
of Mullerian epithelium, we believe that the so called
Brenner tumor is in effect a tumor arising from the
Mullerian epithelium with a tendency to differentiate
into vaginocervical type epithelium. 相似文献
92.
93.
应用低严格度—单引物聚合酶链反应对问号钩体中国参考株的… 总被引:1,自引:0,他引:1
G1、G2引物是对问号钩体具有特异性引物。分别用G1或G2单引物对问号钩体中国参考株进行前4个低严格度循环的PCR扩增,扩增带谱显示赖型、犬型、致热型、秋季型、澳洲型、临海型、乌尔夫型、溶血型为一类,而爪哇型、拜伦型、波摩那型、七日热型、巴叶赞型塔拉索夫型、曼耗Ⅱ型是不与以上赖型等血清型本为一类,双曲钩体atoc型及伊利尼细丝体伊利尼型的扩增带谱与问号钩体截然不同。应用苯酚法提取的高纯度钩体DNA 相似文献
94.
Michael D Seidman Mumtaz J Khan Wen Xue Tang Wayne S Quirk 《Otolaryngology--head and neck surgery》2002,127(3):138-144
OBJECTIVES: Lecithin is a polyunsaturated phosphatidylcholine (PPC), which are high energy functional and structural elements of all biologic membranes. PPC play a rate-limiting role in the activation of numerous membrane-located enzymes, including superoxide dismutase and glutathione, which are important antioxidants protecting cell membranes from damage by reactive oxygen species (ROS). ROS-induced damage to mitochondrial DNA may lead to reduced mitochondrial function in the cochlea and resultant hearing loss. STUDY DESIGN AND SETTING: The effects of lecithin on aging and age-associated hearing loss were studied in rats by measuring hearing sensitivities using auditory brainstem responses (ABR). In addition, mitochondrial function as a measure of aging was assessed by determining mitochondrial membrane potentials using flow cytometry and by amplifying mitochondrial DNA deletions associated with aging. Harlan-Fischer rats aged 18 to 20 months (n = 14) were divided into 2 groups. The experimental group was supplemented orally for 6 months with lecithin, a purified extract of soybean phospholipid (Nutritional Therapeutics, Allendale, NJ). RESULTS: The data obtained were compared with the control group. ABRs were recorded at 2-month intervals and showed significant preservation of hearing sensitivities in the treated subjects. Flow cytometry revealed significantly higher mitochondrial membrane potentials in the treated subjects, suggesting preserved mitochondrial function. Finally, the common aging mitochondrial DNA deletion (mtDNA(4834)) were amplified from brain and cochlear tissue including stria vascularis and auditory nerve. This specific deletion was found significantly less frequent in all tissues in the treated group compared with the controls. CONCLUSION: These experiments support our hypothesis and provide evidence that lecithin may preserve cochlear mitochondrial function and protect hearing loss associated with aging. 相似文献
95.
BACKGROUND: Reduced Th1 and elevated Th2 cytokine responses are considered to be a principal mechanism in the generation of the inflammation leading to the manifestations of atopic disease in the skin of atopic dermatitis and in the airways of asthma. If reduced Th1 and elevated Th2 responses are principal determinants of the manifestation of atopic disease it might be expected that subjects with established disease would exhibit differences in their cytokine profiles as compared with atopic patients without clinical disease. OBJECTIVE: To determine whether asymptomatic atopic children exhibit a cytokine imbalance similar to that seen in patients with established atopic disease or if they behave like non-atopic controls. Cytokine responses in a group of children with elevated IgE but no clinical manifestations of disease, atopic children with established disease and non-atopic controls were compared. METHODS: We examined allergen-induced (house dust mite, HDM, rye grass pollen and RYE) cytokine responses in parallel with polyclonal (staphylococcal enterotoxin B, SEB) cytokine responses in a group of children with elevated serum IgE levels without current or past evidence of atopic disease (median age 6.6 years) and compared these with a non-atopic control group (median age 6.5 years) and a group of children with atopic disease (median age 6.7 years). RESULTS: Symptomatic atopic children had reduced SEB-induced IFN-gamma and increased SEB-induced IL-4 and IL-5 as compared with non-atopic controls. In contrast, SEB-induced IFN-gamma, IL-4 and IL-5 production in asymptomatic atopics was not significantly different from the non-atopic control subjects. Allergen-induced Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production was increased in both symptomatic atopics and asymptomatic atopics when compared with non-atopic controls. CONCLUSION: The defect in polyclonally induced IFN-gamma production was associated with the clinical manifestation of atopic disease but not the atopic stateper se. This suggests that the global reduction in IFN-gamma is the key determinant of the development of overt atopic disease. In contrast, elevated allergen-induced Th2 cytokine responses in children related to the atopic state per se irrespective of the presence of clinical atopic disease. 相似文献
96.
Serologic epidemiology of hepatitis B viral infection and observation on the immunologic effect of hepatitis B vaccine 总被引:1,自引:0,他引:1
Q Y Ge 《中华预防医学杂志》1988,22(2):92-94
97.
Adenophora polysaccharides (AP), is an active principle extracted from the root of Adenophorae Potaninii Korsh originated in Gansu Province and isolated with boiling water(1). AP is isolated and purified from the crude drug by DEAE-cellulose and Sephadex G-200 column, with a white powder and mean molecular weight of 8.3 × 104 , and [α]D20of AP is 68(1). AP is only composed of glucose judging from the analysis of it with patina chromatography (PC) and gas chromatography-mass spectrometer (GC-MS) methods.The methylation analysis showed that AP is composed of (1→6) linked glucose residues. The measure of nuclear magnetic resonance imaging (NMR) 1H NMR and 14C NMR techniques further proved that AP is α(l→6) linked by Dglucose. The structure of AP is as follows: -[→6]α-D-Glu(1-)n→ (2). 相似文献
98.
J. Benatar-Haserfaty J. Q. Tercero-Lpez A. Coronado-Toural A. Muriel-García 《Ambulatory Surgery》2004,11(1-2):15-18
The objectives of this study were to consider the effectiveness of local anaesthesia (LA) for office-based vitreoretinal (VR) surgery, the requirement to supplement the anaesthetic blockade, the demographic pattern of the sample and the acceptance of LA by patients. This prospective observational audit involved 111 patients that had undergone 128 VR procedures. Assessment data included: patient’s information, details of type of anaesthetic, and pain during surgery. A clinical audit was also carried out with telephone survey to establish the postoperative use of analgesics, the frequency of nausea, emesis, and insomnia. Results suggest that VR surgery can be carried out effectively and safely with LA, in an office-based surgery, provided that experienced surgeons exist. We noted a high degree of patient acceptance, a reasonable level of postoperative pain and a low frequency of nausea and vomits. 相似文献
99.
OBJECTIVE: To study the expression of S100 in oral submucose fibrosis(OSF). METHODS: Immunohistochemistry assay was performed on 10 cases of OSF, 10 cases of oral epithelial dysplasia (OED) and 8 cases of normal oral epithelium using monoclonal antibody against S100 protein. RESULTS: S100 did not express in the normal oral muscosal epithelium. The S100 positive nuclear staining was found in 50% of the OSF and OED cases, which was significantly higher than that in the normal oral epithelium (P < 0.05). But the positive staining in the OSF and OED cases had no difference (P > 0.05). CONCLUSION: S100 expression is closely related to the development of OSF and OED. The positive staining expression in the OSF and OED cases is the same. 相似文献
100.
BACKGROUND: Prior treatment with local hyperthermia has been shown to prevent mast cell degranulation and leucocyte histamine release, and to reduce mortality and cellular infiltrates in a model of acute lung injury. Local hyperthermia is effective in reducing the symptoms of the common cold and perennial and seasonal allergic rhinitis, nasal patency also being improved in rhinitis. It is possible that these effects are mediated by common anti-inflammatory mechanisms, and that this treatment may be effective in the treatment of asthma. The effect of prior local hyperthermia on the response to exercise challenge and histamine bronchoprovocation was therefore examined. METHODS: In a randomised, double blind, placebo controlled, crossover study, 10 asthmatic subjects with exercise induced asthma used machines delivering 40 1/minute of fully humidified air at either 42 degrees C (active treatment) or 31 degrees C (placebo treatment) for 30 minutes' tidal breathing. For each pretreatment, at two week intervals they underwent exercise challenges starting one and 24 hours after starting the inhalations. After a further two weeks the protocol was repeated with histamine substituted for the exercise challenges. RESULTS: The mean (SE) maximum percentage fall in forced expiratory volume in one second (FEV1) was significantly lower one hour after treatment with air at 42 degrees C (30.8% (3.1%)) than after treatment with air at 31 degrees C (22.3% (2.9%)). There was no significant effect on exercise challenge at 24 hours, or on histamine challenge at either time point, though there were nonsignificant trends towards protection with exercise at 24 hours and with histamine at one hour. CONCLUSION: In asthmatic subjects the response to exercise challenge is significantly attenuated one hour after treatment with local hyperthermia. This treatment warrants further investigation in the treatment of clinical asthma and other inflammatory disorders. 相似文献