全文获取类型
收费全文 | 191724篇 |
免费 | 8413篇 |
国内免费 | 549篇 |
专业分类
耳鼻咽喉 | 2729篇 |
儿科学 | 5636篇 |
妇产科学 | 4547篇 |
基础医学 | 25819篇 |
口腔科学 | 6592篇 |
临床医学 | 12555篇 |
内科学 | 46713篇 |
皮肤病学 | 5474篇 |
神经病学 | 15686篇 |
特种医学 | 5064篇 |
外国民族医学 | 7篇 |
外科学 | 23385篇 |
综合类 | 1016篇 |
一般理论 | 54篇 |
预防医学 | 19288篇 |
眼科学 | 3914篇 |
药学 | 13110篇 |
中国医学 | 900篇 |
肿瘤学 | 8197篇 |
出版年
2023年 | 1162篇 |
2022年 | 1610篇 |
2021年 | 4462篇 |
2020年 | 2301篇 |
2019年 | 4391篇 |
2018年 | 7845篇 |
2017年 | 4728篇 |
2016年 | 3998篇 |
2015年 | 4340篇 |
2014年 | 5587篇 |
2013年 | 7890篇 |
2012年 | 12836篇 |
2011年 | 13774篇 |
2010年 | 7227篇 |
2009年 | 5620篇 |
2008年 | 11151篇 |
2007年 | 11679篇 |
2006年 | 10907篇 |
2005年 | 10832篇 |
2004年 | 9766篇 |
2003年 | 9189篇 |
2002年 | 8659篇 |
2001年 | 5496篇 |
2000年 | 6274篇 |
1999年 | 4794篇 |
1998年 | 1130篇 |
1997年 | 783篇 |
1996年 | 746篇 |
1995年 | 642篇 |
1994年 | 507篇 |
1993年 | 474篇 |
1992年 | 2083篇 |
1991年 | 1711篇 |
1990年 | 1587篇 |
1989年 | 1321篇 |
1988年 | 1112篇 |
1987年 | 1107篇 |
1986年 | 1053篇 |
1985年 | 914篇 |
1984年 | 672篇 |
1983年 | 534篇 |
1979年 | 554篇 |
1975年 | 453篇 |
1974年 | 499篇 |
1973年 | 534篇 |
1972年 | 477篇 |
1971年 | 485篇 |
1970年 | 445篇 |
1969年 | 433篇 |
1968年 | 430篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
44.
J I?igo A Arce E Rodríguez D García de Viedma E Palenque M J Ruiz Serrano L Cabello F Chaves 《The international journal of tuberculosis and lung disease》2006,10(5):550-553
SETTING: Tuberculosis (TB) cases reported from nine districts of Madrid, where the percentage of immigrant population varied from 1.9% in 1996 to 12.2% in 2003. OBJECTIVE: To describe the trends in TB incidence from 1994 to 2003. DESIGN: Observational study. RESULTS: Between 1994-1995 and 2002-2003, the TB rate decreased from 48.5 (95% CI 45.8-51.1) to 23.3 per 100000 population (95% CI 21.5-25.1) (P < 0.001). The percentage of TB cases co-infected with HIV decreased from 55.9% in 1994 to 14.3% in 2003 (P < 0.001), whereas TB cases in foreigners increased from 2.6% in 1994 to 33.7% in 2003 (P < 0.001). CONCLUSION: Although the TB rates showed a marked decrease in the study period, the increasing impact of immigration contributed to slowing down the trend. 相似文献
45.
Jesús Hermida J Antonio Casal J Carlos Tutor 《Clinical chemistry and laboratory medicine》2003,41(3):302-305
Using 3,3'-diclorophenolsulfoftaleinil N-acetyl-beta-D-glucosaminide as a substrate, the apparent activation energy of beta-N-acetylhexosaminidase (Hex) was determined in samples of plasma and urine, as well as in leukocyte and platelet lysates. Incubation with papain produced an increase in this thermodynamic variable for plasma Hex (precursor forms with high molecular mass) that would be caused by the proteolytic action of papain on the Hex A isoenzyme. However, digestion with papain did not significantly modify the activation energy of Hex in leukocyte and platelet lysates (mature enzymatic forms). In 11 healthy subjects and 28 patients with different renal diseases, no statistically significant differences were found with regard to the values obtained in cellular lysates for variations in the activation energy of urinary Hex, regardless of whether they presented normoalbuminuria, microalbuminuria or macroalbuminuria. These results support the hypothesis that even in patients with proteinuria, no significant amounts of plasma Hex precursor forms are found in urine samples, and the source of the enzyme activity is the kidney itself. 相似文献
46.
47.
48.
Adalberto Parra Jorge Ramírez-Peredo Rocío Hidalgo Amelia Morales-Toquero Gabriela Velásquez-Ramírez Alejandro Ruiz-Argüelles Guillermo J Ruiz-Argüelles 《Biology of blood and marrow transplantation》2006,12(5):566-572
We compared the functional status of the hypothalamic dopaminergic tone in patients given an allogeneic hematopoietic stem cell transplantation (allo-HSCT) with chronic graft-versus-host disease (GVHD) with that observed in patients with allo-HSCT without chronic GVHD and in healthy controls. The effect of acute dopaminergic blockade with intravenous metoclopramide on serum prolactin (PRL) concentrations was evaluated. Twenty volunteers, 20 to 52 years of age, seronegative for both hepatitis C virus and the human immunodeficiency virus, were studied: (1) 10 clinically healthy men (group 1), and (2) 9 patients with leukemia, and 1 patient with refractory aplastic anemia who underwent allo-HSCT, 5 of whom (3 men and 2 women) developed chronic GVHD (group 2), and 5 (3 men and 2 women) who did not develop chronic GVHD (group 3). Serum PRL concentrations were measured both fasting and after intravenous administration of metoclopramide (10-mg bolus). The area under the PRL curve was calculated. Patients in group 2 were older than those in groups 1 and 3 (P<.018), but their body mass index was similar. Fasting serum PRL concentrations were similar among the 3 groups; however, group 2 had higher PRL concentrations throughout the test (P<.001) and a greater area under the PRL curve than groups 1 and 3 (P<.001), without differences between the last 2 groups. The differences remained significant after adjustment for age (P<.01). Our results in a small group of patients with chronic GVHD after allo-HSCT suggest the existence of an increased functional level of their hypothalamic dopamine tone, which would favor a tendency toward a diminished endogenous production, release of pituitary PRL, or both. This could represent an adaptive mechanism aiming to maintain circulating PRL concentrations within a physiological range. 相似文献
49.
Mariela Dutra Gontijo Moura Soraya de Mattos Camargo Grossmann Linaena Méricy da Silva Fonseca Maria Inês Barreiros Senna Ricardo Alves Mesquita 《Journal of oral pathology & medicine》2006,35(6):321-326
BACKGROUND: Oral hairy leukoplakia (OHL) may be an indicator of the progression of Human Immunodeficiency Virus (HIV)-induced immuno-depression, and the evaluation of risk factors leading to OHL is important in the management of these HIV-infected patients. However, there are few studies that analyze risk factors leading to OHL in the Brazilian population. The aim of this case-control study is to present data about prevalence rates and risk factors leading to OHL in a sample of HIV-infected adults in Brazil. METHODS: This case-control study included 111 HIV-infected patients treated at a clinic for sexually transmitted diseases and HIV. In the initial examinations with dentists, variables were collected from all patients. Diagnosis of OHL was performed in accordance with the International Classification System and cytological features. The Fisher and the chi-squared tests were used for statistical analysis. The proportional prevalence and odds ratio were estimated. RESULTS: Outcome presented a positive, statistically significant association among the presence of OHL and viral load of 3000 copies/mul or greater (P = 0.0001; odds ratio (OR) = 5.8), presence of oral candidiasis (P = 0.0000; OR = 11.1), previous use of fluconazole (P = 0.0000; OR = 24.6), and use of systemic acyclovir (P = 0.032; OR = 4.3). Antiretroviral medication presented a negative, statistically significant association with the presence of OHL (P = 0.002; OR = 8.4). CONCLUSIONS: Prevalence of OHL was 28.8%. Viral load, oral candidiasis, previous use of fluconazole, and systemic acyclovir were determined to be risk factors for OHL. Antiretroviral medication proved to be protective against the development of OHL. 相似文献
50.
Effect of leptin on the regulation of placental hormone secretion in cultured human placental cells.
Raquel Coya Pedro Martul Jaime Algorta Ma Angeles Aniel-Quiroga Ma Angeles Busturia Rosa Se?arís 《Gynecological endocrinology》2006,22(11):620-626
Placenta is an important source of leptin during pregnancy that contributes to the high plasma leptin levels in pregnant women. Leptin and its functional receptors are synthesized in trophoblast cells that, in turn, secrete gestational hormones supporting a paracrine or autocrine role for leptin in the endocrine activity of the placenta. In the present study we examined the effect of leptin on in vitro release of gestational hormones (human chorionic gonadotropin (hCG), human placental lactogen (hPL), progesterone, estrogens and testosterone) by human term placental cells in culture. Placentas at term were obtained immediately after delivery from mothers with uncomplicated pregnancies. Progesterone, hCG, hPL, estradiol, estrone, estriol and testosterone levels were measured by different assays in culture media of cells maintained in monolayer culture after incubation for 12, 24, 48 or 72 h with leptin or placebo. Incubation with leptin did not modify hCG, hPL, progesterone, estriol and estrone secretion for any of the doses and times assayed. However, leptin led to a dose-dependent decrease in estradiol release. This effect was observed when treatment with recombinant human leptin spanned from 12 to 72 h. At this time an increase in testosterone levels was observed in leptin-treated cells versus placebo. These results indicate that leptin can be considered a gestational hormone implied in the endocrine function of the placenta, with an important role in control of the production of steroid reproductive hormones in placental cells in vitro. 相似文献