全文获取类型
收费全文 | 298794篇 |
免费 | 27271篇 |
国内免费 | 17662篇 |
专业分类
耳鼻咽喉 | 2750篇 |
儿科学 | 3678篇 |
妇产科学 | 5101篇 |
基础医学 | 33761篇 |
口腔科学 | 5748篇 |
临床医学 | 38369篇 |
内科学 | 44517篇 |
皮肤病学 | 3612篇 |
神经病学 | 15226篇 |
特种医学 | 10317篇 |
外国民族医学 | 128篇 |
外科学 | 30515篇 |
综合类 | 47477篇 |
现状与发展 | 54篇 |
一般理论 | 40篇 |
预防医学 | 20969篇 |
眼科学 | 7867篇 |
药学 | 31911篇 |
297篇 | |
中国医学 | 17039篇 |
肿瘤学 | 24351篇 |
出版年
2024年 | 1026篇 |
2023年 | 4445篇 |
2022年 | 11240篇 |
2021年 | 14440篇 |
2020年 | 10850篇 |
2019年 | 9485篇 |
2018年 | 10038篇 |
2017年 | 9290篇 |
2016年 | 8591篇 |
2015年 | 13294篇 |
2014年 | 16534篇 |
2013年 | 16008篇 |
2012年 | 23289篇 |
2011年 | 25137篇 |
2010年 | 16616篇 |
2009年 | 13198篇 |
2008年 | 17157篇 |
2007年 | 16649篇 |
2006年 | 15871篇 |
2005年 | 14972篇 |
2004年 | 10144篇 |
2003年 | 9214篇 |
2002年 | 7642篇 |
2001年 | 6487篇 |
2000年 | 6454篇 |
1999年 | 6324篇 |
1998年 | 3507篇 |
1997年 | 3457篇 |
1996年 | 2696篇 |
1995年 | 2621篇 |
1994年 | 2330篇 |
1993年 | 1374篇 |
1992年 | 2118篇 |
1991年 | 1869篇 |
1990年 | 1532篇 |
1989年 | 1383篇 |
1988年 | 1267篇 |
1987年 | 1048篇 |
1986年 | 804篇 |
1985年 | 667篇 |
1984年 | 370篇 |
1983年 | 326篇 |
1982年 | 186篇 |
1981年 | 213篇 |
1980年 | 144篇 |
1979年 | 243篇 |
1978年 | 161篇 |
1977年 | 132篇 |
1974年 | 138篇 |
1972年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Effects of intermittent diethylstilbestrol diphosphate administration on the R3327 rat prostatic carcinoma 总被引:1,自引:0,他引:1
P Russo G Liguori W D Heston R Huryk C R Yang W R Fair W F Whitmore H W Herr 《Cancer research》1987,47(22):5967-5970
Clinical trials have utilized intermittent diethylstilbestrol diphosphate (DES) therapy in advanced symptomatic prostatic carcinoma to diminish the morbidity of standard endocrine therapy. To determine the effect of intermittent DES administration on the Dunning R3327 rat prostatic adenocarcinoma 60 days following tumor implant, 6 groups were randomly assigned: control (N = 8), castrate (N = 10), high dose DES (N = 8, 1.6 micrograms/ml DES continuously in drinking water), low dose DES (N = 10, 0.4 microgram/ml continuously in drinking water), intermittent high dose DES (N = 10, 1.6 micrograms/ml DES in drinking water for 1 week, then off for 3 weeks), and intermittent low dose DES (N = 10, 0.4 microgram/ml DES for 1 week, then off for 3 weeks). Results indicate that low or high dose DES, and intermittent low or intermittent high dose DES during the week of administration were able to reduce serum testosterone to castrate levels (0.1 ng/ml). After withdrawal of intermittent DES, serum testosterone returned toward control levels (1.0 ng/ml). Initial mean tumor burden between control and treatment groups was not significantly different. All DES exposed rats had a tumor volume at death (range, 15.6-18.3 cm3) smaller than control (mean, 25.4 cm3) or castrate (mean, 40.8 cm3) rats. Despite this significant survival advantage from the time of randomization was achieved only in castrate (median survival, 331 days) or high dose DES (median survival, 359 days) groups compared to control (median survival, 225 days). Similarly, significant prolongation in tumor doubling time was achieved only by rats receiving castration or high dose DES. Intermittent DES administration controls tumor volume but does not provide a survival advantage. In this respect, intermittent DES is inferior to castration. 相似文献
103.
Mice deficient for the fifth component of murine complement (C5), unlike normal mice, do not possess the secreted form of C5 in their body fluids and can be readily immunized to serum-derived normal C5. Although macrophages from C5-deficient mice do not secrete C5, they synthesize the precursor form (pro-C5). Therefore contact of T cells with autologous pro-C5 presented by macrophages is theoretically possible. We show that macrophages from C5-deficient mice can indeed stimulate a class II restricted C5-specific T cell clone without addition of exogenous C5. Immunization of C5-deficient mice with autologous pro-C5 induces vigorous C5-specific T cell proliferation and pro-C5 is recognized by C5-specific T cells in vitro, demonstrating that this protein fails to induce tolerance under physiological conditions. Thus, intracellular pro-C5 is processed and presented by C5-deficient macrophages and can activate T cell clones in vitro, yet is neither immunogenic nor tolerogenic for T cells in vivo. 相似文献
104.
本文报告一种新的改良式远端脾肾静脉分流术,即脾静脉与左肾静脉侧侧吻合、脾静脉远端结扎,再将胃冠状静脉结扎。作者经治7例,初步观察疗效较好,术后无死亡,无复发出血,无肝性脑病发生。本文对这种手术的步骤和优点进行了讨论和分析。 相似文献
105.
106.
107.
目的:研究成釉细胞瘤(AB)和牙源性角化囊肿(OKC)中c-mycmRNA的表达,探讨c-myc在AB和OKC中的发生、发展及其生物学意义。方法:使用原位杂交法检测54例AB、16例OKC和7例口腔正常黏膜(NOM)组织中c-mycmRNA的表达,并将AB按原发、复发、恶变分组,结果使用χ2检验进行统计分析。结果:AB、OKC及NOM组织中c-mycmRNA的阳性表达率分别为81.5%(44/54)、75.0%(12/16)和14.3%(1/7),3组比较有显著性差异(χ2=15.488,P<0.05)。原发组AB中c-mycmRNA的阳性表达率为71.0%,复发组为94.7%,恶变组为100.0%,伴随原发、复发、恶变,差异有显著性(χ2=16.912,P﹤0.05)。结论:c-myc表达在AB的发生、发展中有重要作用;c-mycmRNA的表达与AB的临床生物学行为有关,伴随其生物学行为变化,c-mycmRNA表达增强;提示c-myc有可能成为评价预后的有效指标。 相似文献
108.
BACKGROUND AND PURPOSE: There are limited data on the pattern of cancer distribution among adolescents in Taiwan. This study evaluated the characteristics of these rare cancers in a medical center. METHODS: Analyses of the characteristics of malignant neoplasms for patients aged 14 to 17 years at diagnosis were performed for all cases recorded in the tumor registry of Chang Gung Memorial Hospital (CGMH) at Linkou for the period 1995 to 2001. All eligible tumors were categorized in 1 of 12 diagnostic groups according to the scheme of the International Classification of Childhood Cancer (ICCC). Relative frequencies, age, and gender variations and the characteristics of tumor types were analyzed. RESULTS: Cancer was diagnosed in 320 adolescents during the study period. The male/female ratio was 1.17. Leukemia was the leading diagnostic group. The frequency of carcinomas increased with age and was highest among 17-year-olds. In this age group, non-rhabdomyosarcoma soft tissue sarcoma/primitive neuroectodermal tumor (non-RMS STS/PNET), thyroid carcinoma (CA) and ovarian germ cell tumor (GCT) were the 3 most common solid tumors; the embryonal malignancies were rare. Tumors with the greatest male predominance were intracranial GCT (91%), nasopharyngeal CA (87.5%), osteosarcoma (84.6%), and colorectal CA (75%). Tumors with the greatest female predominance were thyroid CA (78.3%), gonadal GCT (75%), and non-RMS/PNET (56.5%). Hepatocellular CA comprised 9.4% of all carcinomas. CONCLUSIONS: The relative frequency and the distribution of histology subtypes among adolescents were between those of childhood and adult cancers. There were marked variations in tumor occurrence between genders and among different ages. 相似文献
109.
110.
J C Shih T L Ko M C Lin M K Shyu C N Lee F J Hsieh 《Ultrasound in obstetrics & gynecology》2004,24(2):202-206
The relationship of large and vascularized chorioangiomas to adverse pregnancy outcome is well recognized. We present a patient with a large placental tumor and signs of impending fetal cardiac failure. The angioarchitecture of the tumor depicted by three-dimensional (3D) power Doppler ultrasound enabled us to accurately diagnose a placental chorioangioma. During the follow-up period, quantitative flow data obtained using 3D power Doppler indicated altered hemodynamics in the tumor and concomitant improvement in the condition of the fetus, enabling us to manage the mother conservatively. Spontaneous delivery occurred at 38 weeks without any complications. This report demonstrates the potential value of 3D power Doppler in prenatal diagnosis and monitoring of pregnancies complicated by large, vascularized chorioangioma. 相似文献