全文获取类型
收费全文 | 62966篇 |
免费 | 4344篇 |
国内免费 | 201篇 |
专业分类
耳鼻咽喉 | 562篇 |
儿科学 | 1813篇 |
妇产科学 | 1434篇 |
基础医学 | 7601篇 |
口腔科学 | 1104篇 |
临床医学 | 6908篇 |
内科学 | 13005篇 |
皮肤病学 | 1035篇 |
神经病学 | 5936篇 |
特种医学 | 2163篇 |
外科学 | 10192篇 |
综合类 | 823篇 |
一般理论 | 109篇 |
预防医学 | 4933篇 |
眼科学 | 1572篇 |
药学 | 4325篇 |
中国医学 | 60篇 |
肿瘤学 | 3936篇 |
出版年
2023年 | 391篇 |
2022年 | 680篇 |
2021年 | 1606篇 |
2020年 | 876篇 |
2019年 | 1494篇 |
2018年 | 1685篇 |
2017年 | 1271篇 |
2016年 | 1325篇 |
2015年 | 1588篇 |
2014年 | 2322篇 |
2013年 | 3034篇 |
2012年 | 4799篇 |
2011年 | 5028篇 |
2010年 | 2745篇 |
2009年 | 2514篇 |
2008年 | 4202篇 |
2007年 | 4362篇 |
2006年 | 4170篇 |
2005年 | 4150篇 |
2004年 | 3804篇 |
2003年 | 3473篇 |
2002年 | 3300篇 |
2001年 | 484篇 |
2000年 | 300篇 |
1999年 | 449篇 |
1998年 | 715篇 |
1997年 | 521篇 |
1996年 | 443篇 |
1995年 | 378篇 |
1994年 | 331篇 |
1993年 | 328篇 |
1992年 | 260篇 |
1991年 | 223篇 |
1990年 | 205篇 |
1989年 | 212篇 |
1988年 | 193篇 |
1987年 | 156篇 |
1986年 | 192篇 |
1985年 | 196篇 |
1984年 | 287篇 |
1983年 | 249篇 |
1982年 | 317篇 |
1981年 | 280篇 |
1980年 | 282篇 |
1979年 | 153篇 |
1978年 | 149篇 |
1977年 | 149篇 |
1976年 | 127篇 |
1975年 | 105篇 |
1974年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Alan A Arslan Anne Zeleniuch-Jacquotte Annekatrin Lukanova Yelena Afanasyeva Joseph Katz Mortimer Levitz Giuseppe Del Priore Paolo Toniolo 《Cancer epidemiology, biomarkers & prevention》2006,15(11):2123-2130
Epidemiologic evidence suggests that a full-term pregnancy may affect maternal risk of breast cancer later in life. The objective of this cross-sectional study was to compare circulating levels of maternal hormones affecting breast differentiation (human chorionic gonadotropin and prolactin) and proliferation [alpha-fetoprotein, insulin-like growth factor I (IGF-I), and estradiol] between women at a low to moderate risk (Asians and Hispanics), as compared with women at a high risk for breast cancer (Caucasians and African-Americans). Between May 2002 and December 2004, a total of 586 pregnant women were approached during a routine prenatal visit. Among them, 450 women (206 Caucasian, 126 Asian, 88 Hispanic, and 30 African-American) met the inclusion criteria and signed the informed consent. Only singleton pregnancies were considered. Blood samples were drawn during the second trimester of pregnancy. Laboratory analyses were done using the IMMULITE 2000 immunoassay system. Gestational age standardized mean levels of estradiol, IGF-I, and prolactin were significantly higher in Hispanic women compared with Caucasian women. Mean concentration of IGF-I was significantly higher in African-American women compared with Caucasian and Asian women. No significant differences in pregnancy hormone levels were observed between Caucasian and Asian (predominantly second-generation Chinese) women in this study. Irrespective of ethnicity, women who had their first pregnancy had substantially higher mean levels of alpha-fetoprotein, human chorionic gonadotropin, estradiol, and prolactin compared with women who previously had at least one full-term pregnancy. These data suggest that circulating pregnancy hormone levels may explain some of the ethnic differences in breast cancer risk. 相似文献
103.
Sclerosing stromal cell tumors of the ovary are an uncommon neoplasm that usually does not produce hormonal imbalances. Most patients showing a hormonal effect from this lesion have had menstrual cycle disturbances. Infertility and endometrial hyperplasia have also been described. One other reported case had masculinizing effects. Other authors have documented elevated levels of both estrogenic and androgenic hormones that corrected after surgery. A case of a pregnant 27-year-old Caucasian with hirsutism on her chin and neck and a male suprapubic hair pattern is presented. Elevated androstenedione, dehydroepiandrosterone, and free testosterone levels were present. A 3-cm left ovarian mass was excised and identified as a sclerosing stromal tumor. The histologic features included a pseudolobular pattern with focal areas of sclerosis and a two-cell population of spindled and polygonal cells. Immunohistochemical studies showed a positive vimentin reaction, weakly positive desmin and muscle-specific actin stains, and a negative cytokeratin stain. Following surgery the hormone levels returned to normal and the hirsutism resolved. A normal female infant without evidence of masculinization was delivered from the patient at term. 相似文献
104.
105.
106.
107.
Photocarcinogenesis and inhibition of intercellular adhesion molecule 1 expression in cells of DNA-repair-defective individuals 下载免费PDF全文
108.
109.
Effect of isoelectric point on biodistribution and inflammation imaging with indium-111-labelled IgG
Caroline I. ten Kate Alan J. Fischman Robert H. Rubin A. J. Fucello D. Riexinger Robert A. Wilkinson Lina Du Ban An Khaw H. William Strauss 《European journal of nuclear medicine and molecular imaging》1990,17(6-8):305-309
Electrostatic effects play an important role in protein interactions and may alter the biodistribution of antibodies. To study the effect of molecular charge on the biodistribution and infection imaging properties of human polyclonal immunoglobulin G (IgG), its iso electric point was varied by changing the level of diethylene triamine penta-acetic acid (DTPA) substitution: 0.8, 0.9, 3.7, 5.1 and 5.9 DTPA/IgG. Biodistributions of the different IgG preparations were determined at 10 min, 1, 6, 24, and 48 h post injection in normal rats, and infection imaging properties were determined in rats withEscherichia coli thigh infections. The biodistribution was significantly affected by pl. The immunoglobulin preparations with 0.9 and 3.7 DTPA/IgG showed faster clearance from the circulation and generally lower accumulation in most organs. The images had a target-to-background ratio of approximately 1.3–2.3:1. These results suggest that even though targeting is not affected by the level of DTPA substitutions, preparations with 0.9 and 3.7 DTPA/IgG may be superior imaging agents because of reduced accumulation by background organs. 相似文献
110.
Alan I. Faden 《Basic & clinical pharmacology & toxicology》1996,78(1):12-17
Abstract: Traumatic injuries to the brain or spinal cord cause tissue damage, in part by initiating reactive biochemical changes. Pharmacological approaches aim to modify this delayed injury response by blocking one or more components of the reactive biochemical/metabolic cascade. This minireview summarizes both historical and recent developments in experimental and clinical treatment of CNS trauma. Potential treatments include: corticosteroids; antioxidants or free radical scavengers; drugs that modify arachidonic acid metabolism, platelet-activating factor antagonists; gangliosides; modulators of monoamine actions; opioid receptor antagonists; thyrotropin-releasing hormone and thyrotropin-releasing hormone analogues; glutamate receptor antagonists; calcium channel blockers; agents that modify the inflammatory/ immune response; and trophic factors. Understanding the mechanisms of action for these compounds can permit rational drug development/application, delineation of the therapeutic window, and laying of the ground-work for evaluating potential synergistic effects of combination treatment strategies. 相似文献