全文获取类型
收费全文 | 208424篇 |
免费 | 3071篇 |
国内免费 | 160篇 |
专业分类
耳鼻咽喉 | 1604篇 |
儿科学 | 7404篇 |
妇产科学 | 3602篇 |
基础医学 | 20452篇 |
口腔科学 | 2179篇 |
临床医学 | 15539篇 |
内科学 | 38714篇 |
皮肤病学 | 1061篇 |
神经病学 | 19555篇 |
特种医学 | 10227篇 |
外国民族医学 | 1篇 |
外科学 | 34669篇 |
综合类 | 2521篇 |
一般理论 | 18篇 |
预防医学 | 19987篇 |
眼科学 | 3175篇 |
药学 | 11350篇 |
中国医学 | 668篇 |
肿瘤学 | 18929篇 |
出版年
2023年 | 185篇 |
2022年 | 316篇 |
2021年 | 891篇 |
2020年 | 544篇 |
2019年 | 893篇 |
2018年 | 22866篇 |
2017年 | 18009篇 |
2016年 | 20132篇 |
2015年 | 1786篇 |
2014年 | 2114篇 |
2013年 | 2538篇 |
2012年 | 9516篇 |
2011年 | 23639篇 |
2010年 | 20308篇 |
2009年 | 12952篇 |
2008年 | 21754篇 |
2007年 | 24071篇 |
2006年 | 2891篇 |
2005年 | 4430篇 |
2004年 | 5401篇 |
2003年 | 6232篇 |
2002年 | 4191篇 |
2001年 | 526篇 |
2000年 | 564篇 |
1999年 | 389篇 |
1998年 | 580篇 |
1997年 | 505篇 |
1996年 | 305篇 |
1995年 | 319篇 |
1994年 | 275篇 |
1993年 | 231篇 |
1992年 | 131篇 |
1991年 | 192篇 |
1990年 | 207篇 |
1989年 | 151篇 |
1988年 | 110篇 |
1987年 | 95篇 |
1986年 | 80篇 |
1985年 | 97篇 |
1984年 | 105篇 |
1983年 | 108篇 |
1982年 | 108篇 |
1981年 | 80篇 |
1980年 | 105篇 |
1979年 | 39篇 |
1978年 | 45篇 |
1974年 | 42篇 |
1938年 | 60篇 |
1932年 | 57篇 |
1930年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Elliott Joshua Bodinier Barbara Whitaker Matthew Delpierre Cyrille Vermeulen Roel Tzoulaki Ioanna Elliott Paul Chadeau-Hyam Marc 《European journal of epidemiology》2021,36(3):299-309
European Journal of Epidemiology - Most studies of severe/fatal COVID-19 risk have used routine/hospitalisation data without detailed pre-morbid characterisation. Using the community-based UK... 相似文献
992.
Melody R. Palmer Daniel S. Kim David R. Crosslin Ian B. Stanaway Elisabeth A. Rosenthal David S. Carrell David J. Cronkite Adam Gordon Xiaomeng Du Yatong K. Li Marc S. Williams Chunhua Weng Qiping Feng Rongling Li Sarah A. Pendergrass Hakon Hakonarson David Fasel Sunghwan Sohn Patrick Sleiman Samuel K. Handelman Elizabeth Speliotes Iftikhar J. Kullo Eric B. Larson Gail P. Jarvik 《Genetic epidemiology》2021,45(1):4-15
993.
The RhoA/Rho kinase pathway regulates nuclear localization of serum response factor 总被引:10,自引:0,他引:10
994.
In many organisms completion of the first meiotic cell division depends on the correct assembly and disassembly of the synaptonemal
complex (SC). This is a structure discovered a little over 50 years ago, which is formed by the close association of axes
of homologous sister chromatid pairs. Its structure varies between organisms, although it retains a common tripartite organization
in species as evolutionarily distant as budding yeast and humans. In mammals it is essential for crossover formation and completion
of meiosis. Components of the mammalian SC have been identified only in the last 15 years, and mouse genetic approaches have
started revealing the importance for this structure only in the past 5 years. Here we discuss the progress that has been made
in the field of the mammalian SC and what approaches could be considered for its further study. 相似文献
995.
Luca Antiga Marina Piccinelli Lorenzo Botti Bogdan Ene-Iordache Andrea Remuzzi David A. Steinman 《Medical & biological engineering & computing》2008,46(11):1097-1112
We present a modeling framework designed for patient-specific computational hemodynamics to be performed in the context of
large-scale studies. The framework takes advantage of the integration of image processing, geometric analysis and mesh generation
techniques, with an accent on full automation and high-level interaction. Image segmentation is performed using implicit deformable
models taking advantage of a novel approach for selective initialization of vascular branches, as well as of a strategy for
the segmentation of small vessels. A robust definition of centerlines provides objective geometric criteria for the automation
of surface editing and mesh generation. The framework is available as part of an open-source effort, the Vascular Modeling
Toolkit, a first step towards the sharing of tools and data which will be necessary for computational hemodynamics to play
a role in evidence-based medicine. 相似文献
996.
Embryo transfer (ET) is the last stage of extracorporal fertilization during which the embryo is placed in the uterine cavity with a medium-filled catheter 2–3 days after in vitro fertilization. While fertilization in the laboratory occurs at very high rates (>:90%), the overall success of the procedure (i.e., take home baby) is still very low (<25%) and assumed to be mainly due to implantation failure. A computational model was developed to simulate ET within the uterine cavity by a fluid-filled catheter inserted into a two-dimensional channel with oscillating walls. The results showed that the speed at which the embryos are injected from the catheter dominates the procedure and controls the velocity of their transport within the uterine cavity. ET at excessively high injection speeds may lead to ectopic pregnancies, while uterine peristalsis affects transverse dispersion only during injection at low injection speeds. The presence of the catheter within the uterus does not affect flow patterns downstream of its tip. The potential risks to implantation failure due to mechanical factors involved in the ET processes are discussed. © 2003 Biomedical Engineering Society.
PAC2003: 8719-j, 8710+e 相似文献
997.
Materials are distributed throughout the body of mammals by fractal networks of branching tubes. Based on the scaling laws of the fractal structure, the vascular tree is reduced to an equivalent one-dimensional, tube model. A dispersion–convection partial differential equation with constant coefficients describes the heterogeneous concentration profile of an intravascular tracer in the vascular tree. A simple model for the mammalian circulatory system is built in entirely physiological terms consisting of a ring shaped, one-dimensional tube which corresponds to the arterial, venular, and pulmonary trees, successively. The model incorporates the blood flow heterogeneity of the mammalian circulatory system. Model predictions are fitted to published concentration-time data of indocyanine green injected in humans and dogs. Close agreement was found with parameter values within the expected physiological range. © 2003 Biomedical Engineering Society.
PAC2003: 8710+e, 8719Hh, 8719Uv 相似文献
998.
Robson C. Gutierre Mizue I. Egami Marta M. Antoniazzi Carlos Jared 《Comparative clinical pathology》2008,17(4):221-228
The caecilians (Amphibia, Gymnophiona) constitute one of the least known groups of terrestrial vertebrates because most species
live underground in quite inaccessible environments. Siphonops annulatus is an exclusively fossorial species and is the most extensively distributed caecilian in South America. Little is known of
this order concerning circulating granulocytes, including their morphological and cytochemical structure and ultrastructure.
This paper is part of a project covering the study of granulocytes in representative species of the order Amphibia. Blood
extensions were carried out and submitted to Leishman, Toluidine Blue, Periodic acid Schiff, Sirius Red and hydrogen o-toluidine peroxide methods. Part of the samples was prepared for conventional transmission electron microscopy. Among granular
leukocytes, mature and immature neutrophils and eosinophils were identified, plus basophils. The most frequent granulocyte
encountered in S. annulatus peripheral blood is the neutrophil. This is a cell with a hyper-segmented nucleus and with a very clear cytoplasm when compared
to the eosinophil, which presents large cytoplasmic acidophilic granules. On the other hand, the basophils present basophilic
and metachromatic granules. Glycogen was detected in the cytoplasm of the neutrophils and eosinophils, while basic protein
rich in amino acids was observed in the eosinophil’s granules. Myeloperoxidase activity was detected in the cytoplasm of the
neutrophils and eosinophils. Neutrophils were ultrastructurally detected with three types of small granules: eosinophils with
large and small spherical granules and basophils with large spherical granules with lamellate structures. 相似文献
999.
Activation of AMP-activated protein kinase in the liver: a new strategy for the management of metabolic hepatic disorders 总被引:14,自引:1,他引:14
Benoit Viollet Marc Foretz Bruno Guigas Sandrine Horman Renaud Dentin Luc Bertrand Louis Hue Fabrizio Andreelli 《The Journal of physiology》2006,574(1):41-53
It is now becoming evident that the liver has an important role in the control of whole body metabolism of energy nutrients. In this review, we focus on recent findings showing that AMP-activated protein kinase (AMPK) plays a major role in the control of hepatic metabolism. AMPK integrates nutritional and hormonal signals to promote energy balance by switching on catabolic pathways and switching off ATP-consuming pathways, both by short-term effects on phosphorylation of regulatory proteins and by long-term effects on gene expression. Activation of AMPK in the liver leads to the stimulation of fatty acid oxidation and inhibition of lipogenesis, glucose production and protein synthesis. Medical interest in the AMPK system has recently increased with the demonstration that AMPK could mediate some of the effects of the fat cell-derived adiponectin and the antidiabetic drugs metformin and thiazolidinediones. These findings reinforce the idea that pharmacological activation of AMPK may provide, through signalling and metabolic and gene expression effects, a new strategy for the management of metabolic hepatic disorders linked to type 2 diabetes and obesity. 相似文献
1000.
Cressey TR Jourdain G Lallemant MJ Kunkeaw S Jackson JB Musoke P Capparelli E Mirochnick M 《Journal of acquired immune deficiency syndromes (1999)》2005,38(3):283-288
OBJECTIVE: To determine nevirapine (NVP) plasma levels during the postpartum period after a single intrapartum NVP dose for the prevention of mother-to-child transmission. METHODS: Plasma samples at delivery and during days 8 to 45 postpartum were obtained from HIV-infected Thai women who received an intrapartum NVP dose in the Perinatal HIV Prevention Clinical Trial-2 (PHPT-2) for the prevention of perinatal HIV transmission. These data were combined with NVP concentration data from 2 phase 1 studies of NVP for a population analysis. RESULTS: The median NVP level fell to 68 ng/mL (range: <50-228, n = 43) 8 to 14 days after dosing and to 51 ng/mL (range: <50-166, n = 25) between 15 and 21 days. During the second and third weeks postpartum, NVP levels were below the limit of quantitation in 23% and 44% of samples, respectively. Between 21 and 45 days, no sample had a quantifiable NVP concentration. A simulation derived from the population analysis predicts that NVP concentration falls to less than 10 ng/mL in 5% of women by 11 days, in 50% of women by 17.5 days, and in 95% of women by 28 days. CONCLUSIONS: Significant NVP concentrations remained for up to 20 days in these Thai women. To ensure that coverage is maintained until NVP concentrations fall to nonsuppressive levels, 1 month of additional antiretroviral treatment after delivery should be considered to prevent the emergence of resistant viruses. 相似文献