全文获取类型
收费全文 | 235647篇 |
免费 | 21138篇 |
国内免费 | 7842篇 |
专业分类
耳鼻咽喉 | 1910篇 |
儿科学 | 3398篇 |
妇产科学 | 2706篇 |
基础医学 | 34161篇 |
口腔科学 | 4832篇 |
临床医学 | 18389篇 |
内科学 | 38563篇 |
皮肤病学 | 3161篇 |
神经病学 | 18036篇 |
特种医学 | 5477篇 |
外国民族医学 | 55篇 |
外科学 | 16481篇 |
综合类 | 30754篇 |
现状与发展 | 24篇 |
一般理论 | 8篇 |
预防医学 | 16250篇 |
眼科学 | 2474篇 |
药学 | 34995篇 |
71篇 | |
中国医学 | 12440篇 |
肿瘤学 | 20442篇 |
出版年
2024年 | 419篇 |
2023年 | 4371篇 |
2022年 | 5810篇 |
2021年 | 11632篇 |
2020年 | 9178篇 |
2019年 | 8084篇 |
2018年 | 7843篇 |
2017年 | 7796篇 |
2016年 | 7810篇 |
2015年 | 8759篇 |
2014年 | 14616篇 |
2013年 | 15974篇 |
2012年 | 13903篇 |
2011年 | 15806篇 |
2010年 | 12865篇 |
2009年 | 13033篇 |
2008年 | 12954篇 |
2007年 | 12070篇 |
2006年 | 10769篇 |
2005年 | 9395篇 |
2004年 | 7831篇 |
2003年 | 7085篇 |
2002年 | 5564篇 |
2001年 | 4687篇 |
2000年 | 3912篇 |
1999年 | 3507篇 |
1998年 | 3128篇 |
1997年 | 2973篇 |
1996年 | 2584篇 |
1995年 | 2355篇 |
1994年 | 2126篇 |
1993年 | 1828篇 |
1992年 | 1584篇 |
1991年 | 1467篇 |
1990年 | 1213篇 |
1989年 | 1041篇 |
1988年 | 985篇 |
1987年 | 826篇 |
1986年 | 728篇 |
1985年 | 1070篇 |
1984年 | 1013篇 |
1983年 | 702篇 |
1982年 | 713篇 |
1981年 | 579篇 |
1980年 | 497篇 |
1979年 | 391篇 |
1978年 | 266篇 |
1977年 | 224篇 |
1976年 | 209篇 |
1975年 | 146篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
中华伍氏百叶散抗大鼠肝癌的实验研究 总被引:1,自引:0,他引:1
目的 :研究中华伍氏百叶散 (WSBYS)的抗癌作用。方法 :通过大鼠体重 ,肝脏病理学为指标 ,观察WSBYS对 2 -乙酰氨基芴 (2 -FAA)诱导的大鼠肝癌的治疗作用。结果 :服用WSBYS治疗的大鼠 ,肝癌病变程度低于阳性对照组 ,体重高于阳性对照组 ,且与剂量大小呈正相关。结论 :WSBYS对 2 -FAA诱导的大鼠肝癌有明显的治疗作用 相似文献
992.
应用链霉亲和素和生物素系统发展成的酶连接免疫吸附测定(ELISA)改良法检测HBeAg,取得较满意效果。标记链霉亲和素-辣根过氧化物酶(SA-HRP)时,两者的重量比以(0.5~0.8):1为佳,浓度以7μg/ml为最理想;SA-HRP的反应时间以30min为适宜。本改良法与生物素亲和素ELISA(BA)法、普通ELISA法检测HBeAg的灵敏度比较,其相对灵敏度高于后二者;用Abbott试剂作为标准,检测HBeAg100人份,其阳性率高于BA法和普通ELISA法。提示链霉亲和素EI,ISA(BSA)法可提高方法的特异性及灵敏度。 相似文献
993.
采用放射免疫法测定实验性胆道炎症兔胆系组织以及几种胆道疾患病人胆系组织中6-keto-PGF1α与TXB2的含量。结果显示:动物模型组与病人组的上述两指标均显著增高;AOSC病人的TXB2增高更明显,而胆道梗阻病人胆管组织无此变化。提示前列腺素类及血栓素对胆道炎症的发生可能有关,TXB2的负性作用尤为重要。 相似文献
994.
Astrocytes respond to the excitatory neurotransmitter glutamate with dynamic spatio-temporal changes in intracellular calcium [Ca2+]i. Although they share a common wave-like appearance, the different [Ca2+]i changes--an initial spike, sustained elevation, oscillatory intracellular waves, and regenerative intercellular waves--are actually separate and distinct phenomena. These separate components of the astrocytic Ca2+ response appear to be generated by two different signal transduction pathways. The metabotropic response evokes an initial spatial Ca2+ spike that can propagate rapidly from cell to cell and appears to involve IP3. The metabotropic response can also produce oscillatory intracellular waves of various amplitudes and frequencies that propagate within cells and are sustained only in the presence of external Ca2+. The ionotropic response, however, evokes a sustained elevation in [Ca2+]i associated with receptor-mediated Na+ and Ca2+ influx, depolarization, and voltage-dependent Ca2+ influx. In addition, the ionotropic response can lead to regenerative intercellular waves that propagate smoothly and nondecrementally from cell to cell, possibly involving Na+/Ca2+ exchange. All these astrocytic [Ca2+]i changes tend to appear wave-like, traveling from region to region as a transient rise in [Ca2+]i. Nevertheless, as our understanding of the cellular events that underlie these [Ca2+]i changes grows, it becomes increasingly clear that glutamate-induced Ca2+ signaling is a composite of separate and distinct phenomena, which may be distinguished not based on appearance alone, but rather on their underlying mechanisms. © 1994 Wiley-Liss, Inc. 相似文献
995.
The glucose clamp technique is currently regarded as the standard test for measuring insulin sensitivity against which other methods are compared but is unsuitable for routine screening of patients outside a hospital base. There is thus a need for a simpler test to measure insulin sensitivity. We have therefore compared the glucose disappearance rate KITT in the first 15 min of the insulin tolerance test (ITT) with the M and M/I values derived from the standard euglycaemic clamp in nine normal subjects and eight subjects with Type 2 (non-insulin dependent) diabetes mellitus and coexisting obesity. All subjects underwent the ITT and euglycaemic clamp in random order. Nine subjects later had a repeat ITT to determine the reproducibility of the test. In the ITT, 0.1 U kg-1 body weight, human Actrapid insulin was given as an IV bolus and simultaneous arterialized and venous blood samples were obtained every minute for 15 min. The first order rate constant for the disappearance of glucose KITT over the period 3-15 min was taken as a measure of insulin sensitivity. The euglycaemic clamp was performed with an insulin infusion of 50 mU kg-1 h-1 for 120 min and a variable rate glucose infusion to maintain blood glucose concentration at 0.5 mmol l-1 below fasting level to minimize the effect of endogenous insulin secretion. The ratio of the mean rate of glucose infused (M, mumol kg-1 min-1) to the plasma insulin over the last 30 min of the clamp was taken as a measure of tissue sensitivity to insulin (M/I) assuming endogenous glucose output was suppressed.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
996.
反义核酸技术是用人工合成的或生物合成的特定互补的DNA或RNA片段阻断从基因到蛋白的信息流 ,以达到抑制或阻断基因表达的生物新技术。利用核酸分子杂交原理将反义寡核苷酸 (antisenseoligonucleotide,ASON)作为外源性基因表达抑制物结合到靶mRNA序列上阻止其翻译成蛋白[1 ] 。具有杂交特异性和选择性调节基因的表达的特点[2 ] ,这一技术不仅已成为常用的实验室研究方法 ,还广泛的应用于研究病毒、肿瘤、寄生虫和遗传性疾病的预防和治疗 ,具有重要的应用前景。对于人类基因的研究 ,人们采用分子克隆、分子杂交、PCR技术等一系列研究… 相似文献
997.
Summary Prognostic factors define the study population, help formulate the study objectives, and influence the treatment strategies. They must be accounted for in the study analysis to obtain valid estimates of the treatment differences and to evaluate results across studies. The causal relationship between a prognostic factor and the study endpoint can only be established through prospective randomized study designs. Potential factors discovered through retrospective analysis must be verified to establish their validity. Using such factors prematurely to select patient population and treatment strategy for a new study will not establish the validity of the potentially important factor.Supported by NCI 5 PO1 CA53996-15 and NCI 5 U10 CA38926-08. 相似文献
998.
7例晚期瘤性胸水的肿瘤浸润淋巴细胞(TIL)经体外诱导培养3~12d,扩增1~9倍.其CD8及IL-2R阳性细胞百分率增加2.43和2.76倍;NK活力增加3.29倍,与培养前后比较有显著差异。TIL/rIL-2(重组人白细胞介素2)胸腔内回输后,4例胸水及胸水中肿瘤细胞消失,癌胚抗原(CEA)回至正常水平,2例胸水减少,1例因多房性胸水停止治疗,CEA水平上升。经1~8个月随访患者心、肝、肾功能正常。 相似文献
999.
本文观察16例大肠癌病人的癌组织培养上清液对人T细胞的增殖,ZL—2产生的影响和病理Dukes分期的关系,发现癌组织的TDSF对T细胞的增殖有显著抑制作用,对ZL—2的产生抑制作用不明显,对T细胞增殖率在DukesA与B期,其值与对照有显著差异(0.01P<0.05).在C期有非常显著差异(P<0.01).说明大肠癌组织确实分泌有能造成宿主免疫功能下降的抑制物质.且免疫作用不是通过ZL—2环节发生. 相似文献
1000.
Pertti Pohjolainen 《Journal of cross-cultural gerontology》1991,6(1):109-117
This study focuses on changes occurring in one area of life-style, social participation during retirement. The population consisted of four cohorts, born in 1905–06, 1909–10, 1917–18, and 1921–22. In the longitudinal study the members of the oldest cohort were interviewed five times at the ages of 66, 70, 74, 78 and 82 years. In the cohort study the subjects were interviewed at the age of 66. Interests decreased after the age of 78 among men and women. Also, formal social participation declined with age among men and women. There were no cohort differences among men, but among women formal social participation was higher in the younger cohorts than in the older ones. In the longitudinal study education correlated positively with the interests index at almost all ages among both men and women. In the cohort study correlations between interests index and education were lower in the younger cohorts than in the older ones.Paper originally presented at the XIVth International Congress of Gerontology, Acapulo, Mexico 18–23 June 1989. 相似文献