全文获取类型
收费全文 | 28421篇 |
免费 | 2537篇 |
国内免费 | 1683篇 |
专业分类
耳鼻咽喉 | 264篇 |
儿科学 | 302篇 |
妇产科学 | 339篇 |
基础医学 | 3504篇 |
口腔科学 | 448篇 |
临床医学 | 3725篇 |
内科学 | 4589篇 |
皮肤病学 | 223篇 |
神经病学 | 1833篇 |
特种医学 | 1100篇 |
外国民族医学 | 24篇 |
外科学 | 3051篇 |
综合类 | 3975篇 |
现状与发展 | 5篇 |
一般理论 | 16篇 |
预防医学 | 1930篇 |
眼科学 | 680篇 |
药学 | 2852篇 |
12篇 | |
中国医学 | 1282篇 |
肿瘤学 | 2487篇 |
出版年
2024年 | 79篇 |
2023年 | 375篇 |
2022年 | 962篇 |
2021年 | 1282篇 |
2020年 | 939篇 |
2019年 | 856篇 |
2018年 | 972篇 |
2017年 | 841篇 |
2016年 | 873篇 |
2015年 | 1288篇 |
2014年 | 1483篇 |
2013年 | 1331篇 |
2012年 | 2165篇 |
2011年 | 2228篇 |
2010年 | 1428篇 |
2009年 | 1157篇 |
2008年 | 1604篇 |
2007年 | 1659篇 |
2006年 | 1659篇 |
2005年 | 1538篇 |
2004年 | 1233篇 |
2003年 | 1251篇 |
2002年 | 1082篇 |
2001年 | 577篇 |
2000年 | 517篇 |
1999年 | 506篇 |
1998年 | 310篇 |
1997年 | 336篇 |
1996年 | 277篇 |
1995年 | 264篇 |
1994年 | 224篇 |
1993年 | 158篇 |
1992年 | 192篇 |
1991年 | 159篇 |
1990年 | 145篇 |
1989年 | 89篇 |
1988年 | 88篇 |
1987年 | 79篇 |
1986年 | 61篇 |
1985年 | 60篇 |
1984年 | 58篇 |
1983年 | 22篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1974年 | 9篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
研究目的探讨苯酞类天然产物的合成方法及其生物活性。研究方法以邻苯二甲酐为底物,首先引入丁烯基,再进行烯丙位氧化,制得目标化合物。结果通过丁基锂反应,得到了具有药物活性的丁烯基苯酞,然后利用SeO2烯丙位氧化,首次合成了Z-3-(2-羟基丁烯基)苯酞。结论此合成方法原料易得,方法简便,为苯酞类化合物的合成研究提供了一个新的途径。 相似文献
42.
某化工厂1987~2000年164例工伤事故调查分析 总被引:2,自引:0,他引:2
目的调查分析某化工厂工伤事故的分布规律及其危险因素,以便采取相应的预防干预措施。方法对1987~2000年该化工厂发生的工伤事故进行回顾性调查分析,建立数据库,并统计分析。结果 ①事故以轻伤为主,约占80.0%。②事故类别主要是灼烫烧伤和机械伤害,分别为工伤事故总数的35.8%、28.5%。③工伤伤害性质以骨折多见,约为总数的56.1%。④受伤工人的年龄分布以30~40岁段为主,约为总数的31.1%。⑤工伤事故原因中注意力不集中和违反操作规程分别为总数的43.0%,38.3%。结论12根据上述流行病学特点,采取相应的措施来减少工伤事故的发生。 相似文献
43.
目的 了解湘西自治州重点人群性病患消长趋势,为性病防治工作提供科学依据。方法 从1995年起,采用统一的表格,每年对湘西州劳教所新入教人员进行一次法定性病监测。结果 三种法定性病平均患病率为14.64%(4.96~26.7%),以1995年最低,1997年最高,8年未发现HIV/AIDS,患病率以20~39岁的性跃期人群为最高,汉族患病率高于其它民族;化程度越高,患病率越低。结论 男性劳教人员作为性病患病的高危人群,是哨点监测理想的目标人群。 相似文献
44.
45.
A promising technique for transplantation of bone marrow-derived endothelial progenitor cells into rat heart. 总被引:2,自引:0,他引:2
Cheng Qian René A Tio Anton J M Roks Kristien M Boddeus Martin C Harmsen Wiek H van Gilst Regien G Schoemaker 《Cardiovascular pathology》2007,16(3):127-135
OBJECTIVE: To investigate the feasibility of intracoronary application of endothelial progenitor cells and the subsequent distribution within the heart. METHODS: Endothelial progenitors cells (EPCs) cultured from rat bone marrow were identified by double-positive staining with Dil-Ac-LDL and BS1-lectin. Twenty-four hours before cell transplantation, EPCs were labeled with 5-bromo-2'-deoxyuridine (BrdU). Cells (5 x 10(5) in 250-microl medium) were injected into healthy rats, either as intracoronary application (n=11) or as intramyocardial injection (n = 6). At 15 min or 3 days posttransplantation, hearts as well as other organs (lung, liver, kidney, and spleen) were collected and processed for subsequent BrdU immunohistochemistry. The number of BrdU-positive cells per tissue area was counted. RESULTS: Compared to intramyocardial injection, intracoronary administration resulted in more than twice as much positive cells in the heart (P < .05), with no local differences within the heart. Whereas after 15 min, EPCs were equally distributed in all examined organs (except for the spleen), cells that were still present after 3 days, approximately 10%, were selectively restricted to the heart. CONCLUSIONS: Our data indicate that the intracoronary application provides a promising technique for EPC transplantation in the rat heart. 相似文献
46.
47.
The dependence of twitch relaxation on sodium ions and on internal Ca2+ stores in voltage clamped frog atrial fibres 总被引:5,自引:0,他引:5
Marie-Jeanne Roulet K. G. Mongo G. Vassort Renée Ventura-Clapier 《Pflügers Archiv : European journal of physiology》1979,379(3):259-268
Frog heart relaxation was analyzed under voltage clamp conditions as the tension decay observed after the membrane potential had been returned to its resting value. The tension decayed exponentially with a time constant of 188±3.8 ms SEM. The relaxation rate decreased with the external Na concentration. It fell to about one tenth in a Na-free solution. Increasing the intracellular Na-content by an application of veratrine also decreased the relaxation rate. Thus relaxation seems dependent on the Na gradient. The relaxation rate decreased within one second upon switching from a high to a low Na-containing solution. The relaxation rate reached a minimum before rising slightly to a new steady state value. This rebound may reflect the partial recovery of the Na gradient since a fast variation in [Na]i follows alteration of [Na]o. Mn and La ions also slowed relaxation. In a Na-free solution, adrenaline accelerated tension decay, an effect not noticeable in frog heart contained in Ringer solution. Other cAMP-promoting agents, such as dibutyryl-cAMP and aminophylline, also increased relaxation rate.It is concluded that in frog myocardium, part of the decrease of the intracellular Ca2+-concentration which occurs during each cardiac cycle could be dependent on a Na–Ca exchange mechanism. The relative importance of this mechanism, versus internal Ca sequestration, in the relaxation of tension may well be greater in contractile tissues whose cells have a large surface/volume ratio. 相似文献
48.
René?G?ddeEmail author Stefanie?Brune Peter?Jagiello Eckhart?Sindern Michael?Haupts Sebastian?Schimrigk Norbert?Müller J?rg?T?Epplen 《Journal of negative results in biomedicine》2005,4(1):7
Apoptosis, the programmed death of cells, plays a distinct role in the etiopathogenesis of Multiple sclerosis (MS), a common
disease of the central nervous system with complex genetic background. Yet, it is not clear whether the impact of apoptosis
is due to altered apoptotic behaviour caused by variations of apoptosis-related genes. Instead, apoptosis in MS may also represent
a secondary response to cellular stress during acute inflammation in the central nervous system. Here, we screened 202 apoptosis-related
genes for association by genotyping 202 microsatellite markers in initially 160 MS patients and 160 controls, both divided
in 4 sets of pooled DNA samples, respectively. When applying Bonferroni correction, no significant differences in allele frequencies
were detected between MS patients and controls. Nevertheless, we chose 7 markers for retyping in individual DNA samples, thereby
eliminating 6 markers from the list of candidates. The remaining candidate, the ERBB3 gene microsatellite, was genotyped in additional 245 MS patients and controls. No association of the ERBB3 marker with the disease was detected in these additional cohorts. In consequence, we did not find further evidence for apoptosis-related
genes as predisposition factors in MS. 相似文献
49.
Detection of circulating Aspergillus fumigatus galactomannan: value and limits of the Platelia test for diagnosing invasive aspergillosis 总被引:8,自引:0,他引:8
Pinel C Fricker-Hidalgo H Lebeau B Garban F Hamidfar R Ambroise-Thomas P Grillot R 《Journal of clinical microbiology》2003,41(5):2184-2186
The effectiveness of galactomannan detection with the Platelia test was evaluated in a prospective study of 3,327 sera from 807 patients. The specificity was 99.6% (748 of 751 cases). For the groups of patients with proven and probable invasive aspergillosis, the sensitivity was 50.0% (17 of 34 cases). The disappointing sensitivity associated with the presence of rare false-positive cases underlines the limits of this test. 相似文献
50.
甲状腺疾病患者血清可溶性白细胞介素2受体测定的临床意义 总被引:2,自引:0,他引:2
某些甲状腺疾病时血清可溶性白细胞介素2受体(sIL-2R)水平及其与游离甲状腺素(FT_4)、游离三碘甲腺原氨酸(FT_3)和促甲状腺素(TSH)水平的相关性比较。结果发现甲状腺机能亢进症(甲亢)未治疗组(A)及甲亢未治疗伴突眼组(D)血清sIL-2R明显升高;甲状腺机能减退症(甲减)经治疗甲状腺功能灭常组(G)sIL-2R明显高于甲减未治疗组(F);10例毒性弥漫性甲状腺肿(Graves病)患者经抗甲状腺药物治疗后sIL-2R明显降低;Graves病及甲减患者血清sIL-2R均与FT_3呈正相关。提示除自身免疫外,甲状腺素水平也是甲状腺疾病患者血清sIL-2R水平的重要调节因素。 相似文献