全文获取类型
收费全文 | 170465篇 |
免费 | 13506篇 |
国内免费 | 8998篇 |
专业分类
耳鼻咽喉 | 1374篇 |
儿科学 | 2682篇 |
妇产科学 | 3500篇 |
基础医学 | 19707篇 |
口腔科学 | 2829篇 |
临床医学 | 20175篇 |
内科学 | 31203篇 |
皮肤病学 | 2126篇 |
神经病学 | 10925篇 |
特种医学 | 5953篇 |
外国民族医学 | 72篇 |
外科学 | 19085篇 |
综合类 | 20856篇 |
现状与发展 | 25篇 |
一般理论 | 6篇 |
预防医学 | 10103篇 |
眼科学 | 4198篇 |
药学 | 16541篇 |
123篇 | |
中国医学 | 6977篇 |
肿瘤学 | 14509篇 |
出版年
2024年 | 415篇 |
2023年 | 2199篇 |
2022年 | 5638篇 |
2021年 | 7393篇 |
2020年 | 5191篇 |
2019年 | 5124篇 |
2018年 | 5280篇 |
2017年 | 4651篇 |
2016年 | 4467篇 |
2015年 | 6485篇 |
2014年 | 8210篇 |
2013年 | 8185篇 |
2012年 | 11636篇 |
2011年 | 12505篇 |
2010年 | 7615篇 |
2009年 | 6271篇 |
2008年 | 8859篇 |
2007年 | 8892篇 |
2006年 | 8738篇 |
2005年 | 8544篇 |
2004年 | 6383篇 |
2003年 | 5874篇 |
2002年 | 5057篇 |
2001年 | 4628篇 |
2000年 | 4637篇 |
1999年 | 4676篇 |
1998年 | 2680篇 |
1997年 | 2495篇 |
1996年 | 1913篇 |
1995年 | 1725篇 |
1994年 | 1512篇 |
1993年 | 1026篇 |
1992年 | 1892篇 |
1991年 | 1638篇 |
1990年 | 1466篇 |
1989年 | 1370篇 |
1988年 | 1168篇 |
1987年 | 1086篇 |
1986年 | 908篇 |
1985年 | 778篇 |
1984年 | 508篇 |
1983年 | 388篇 |
1982年 | 234篇 |
1981年 | 210篇 |
1980年 | 165篇 |
1979年 | 331篇 |
1978年 | 187篇 |
1977年 | 150篇 |
1974年 | 187篇 |
1973年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The authors compared the inhaled methacholine and exercise responses in 22 stable unmedicated asthmatic patients. The exercise and methacholine challenges were performed at one to three week intervals. Bronchial responsiveness to methacholine was measured in relation to the concentration of methacholine (PC20M). The response to exercise was expressed as the percentage of fall in FEV1, from the pre-exercise FEV1 The findings showed that 21 of 22 subjects demonstrated a fall in FEV1, of more than 20% after methacholine challenge, while only 9/22 subjects experienced a similar decrease in FEV1. All 9 of these positive response exercise cases completed three consecutive exercise challenges prior to the methacholine challenge. Of these cases, five were refractory to the repeated exercise challenge, and the PD20M at the nonexercise stage was significantly lower than the postexercise state. In fact, the methacholine challenge sensitivity actually decreased (PD20 increased) after repeated exercise. The authors concluded that methacholine seems to be a more sensitive bronchial provocation test than exercise. Second, only 55.6% of the exercise test-positive subjects were refractory to the second exercise challenge. Therefore, other factors besides the release of mediators should be considered in exercise induced asthma. Third, methacholine sensitivity actually decreased (PD20 increases) after repeat exercise challenge. 相似文献
82.
本文采用去垢剂透析法成功制备出携载SOD的脂质体(L-SOD),其直径为102nm,对SOD的包裹率为21%,90%以上酶活性存在于脂质体内部。将L-SOD注射到大鼠静脉血中,其半衰期超过4h,明显长于天然SOD(8min)。表明L-SOD优于天然SOD,具有临床应用前景。 相似文献
83.
白细胞介素—2新的功能位点及其中枢镇痛作用 总被引:2,自引:0,他引:2
白细胞介素-2(IL-2)不仅是重要的免疫调节因子,而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标,发现侧脑室注射IL—2能显著提高动物痛阈,并能被纳洛酮所阻断,表示IL-2的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性IL-2实查体仍具有中枢镇痛作用,表明IL—2分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断IL—2的中枢镇痛作用,而不能影响IL—2增殖CTLL-2细胞的作用,提示IL-2发挥镇痛和免疫调节作用可能通过不同的受体途径。IL-2分子中第45位Tyr残基突变为Val后,虽仍保留了免疫活性,但丧失了镇痛功能,表示45位Tyr残基是IL—2发挥中枢镇痛功能的关键残基之一。我们推测IL—2的镇痛功能位点可能在IL—2分子中第45位Tyr残基附近区域。 相似文献
84.
B B Toner E Koyama P E Garfinkel K N Jeejeebhoy I Di Gasbarro 《International journal of psychiatry in medicine》1992,22(1):99-103
The Marlowe-Crowne Social Desirability Scale, a 33-item self-report questionnaire, was administered to an age-matched sample of twenty-five irritable bowel syndrome (IBS) patients, twenty-four psychiatric patients meeting a diagnosis of major depression, and nineteen controls. As predicted, planned comparisons analysis showed a significant group effect: IBS group scores were significantly higher than both depressed and control group scores (p less than .05). Implications of this social desirability response set for the psychological assessment and treatment of IBS are discussed. 相似文献
85.
86.
87.
本文报告口服Sumatriptan 100mg对偏头痛急性发作119例次的治疗结果。治疗后4h内显效91例次(76.5%),好转16例次(13.4%),无效12例次(10.1%),总有效率为89.9%。对偏头痛伴随症状恶心、呕吐和畏光、畏声的缓解率分别为94.2%、96%和94.3%。 相似文献
88.
F Di Costanzo R Bartolucci F Calabresi M Sofra M Marzola V Belsanti C Boni M Bacchi 《Annals of oncology》1992,3(5):371-376
One hundred eighty-one patients with measurable recurrent or metastatic colorectal cancer, who had not received prior chemotherapy, were randomized in a prospective controlled trial to receive 5-fluorouracil (5FU), 13.5 mg/kg, for five days (arm A) or high-dose folinic acid [Cyanamid-Lederle, Italy] (FA), 200 mg/m2, for five days and 5FU, 400 mg/m2 for five days (arm B). The treatments were repeated every four weeks. One hundred fifty-five patients were evaluable for response. The two arms were balanced for all potential prognostic factors studied. The response rate (CR+PR) was 18% in the 5FU arm and 16% in the 5FU plus FA arm. Median duration of response was 56 weeks for 5FU alone and 42 weeks for the combination (p = 0.48). Median time to failure (TTF) was 20 weeks for arm A and 21 for arm B (p = 0.62). Median survival was 62 weeks on the 5FU arm and 53 weeks on the FA plus 5FU arm (p = 0.14). Dose intensity (DI) delivered was the same in both arms. Diarrhea and mucositis were the most frequent adverse reactions in arm B; 20% of the patients in arm A and 38% of those in arm B experienced diarrhea (p = 0.008). Mucositis occurred in 34% of patients in arm A and 42% in arm B (p = 0.04). In general nausea and vomiting were moderate. Hematological toxicity was more severe in patients treated with 5FU alone: 31% in arm A and 14% in arm B developed leukopenia (p = 0.015). In the combination arm one patient died due to gastrointestinal and hematological toxicity after the seventh cycle. This study indicates that, in advanced colorectal cancer, the combination of high-dose FA and 5FU is not superior to 5FU alone when utilized at standard high-dose intensity. 相似文献
89.
The alpha subunit of the nicotinic acetylcholine receptor (AChR) seems crucial in the pathogenesis of the autoimmune paralysis myasthenia gravis (MG) because it contains both the epitopes that dominate the antibody response against the AChR and those recognized by CD4+ AChR-specific T helper (Th) cells. To define the repertoire of anti-AChR Th cells, we investigated the response of unselected blood CD4+ cells or total lymphocytes, or both, from 22 MG patients to 20-residue overlapping synthetic peptides, screening the complete sequence of human-muscle AChR alpha subunit. Several epitopes were identified. Only the most severely affected patients recognized alpha subunit epitopes, and they were mainly young women. Detection of in vitro AChR-specific CD4+ response was facilitated by removal of the CD8+ cells because in two patients a clear response to several alpha subunit peptide sequences could be detected when CD(8+)-depleted cells were used, while their total peripheral blood mononuclear cell population did not respond to any alpha subunit peptide. Although each patient had a unique pattern of peptide recognition, four immunodominant regions recognized by long-term AChR-specific CD4+ T-cell lines, or flanking peptide sequences, were recognized most frequently (residues 48-67, 101-137, 293-337, and 308-437). 相似文献
90.
C Caruso G Di Lorenzo M A Modica G Candore M R Portelli G Crescimanno A Ingrassia G B Sangiorgi A Salerno 《Mechanisms of ageing and development》1991,59(1-2):27-35
The evidence from several studies indicates that as individuals age, they may display immune dysfunctions, mostly T cell dysfunctions. Recently, a soluble form of the receptor for interleukin-2 (IL-2) (sIL-2R) has been demonstrated in human sera and in vitro stimulated culture supernatants from human T lymphocytes. In the present paper, we report in vitro sIL-2R production from peripheral blood mononuclear cells in elderly subjects. The results show that no difference exists for unstimulated cultures, whereas after mitogen stimulation the elderly subjects showed the lowest values compared with young ones. These findings suggest that sIL-2R may provide a new tool for the study of T lymphocyte dysfunctions in old age. 相似文献