全文获取类型
收费全文 | 56388篇 |
免费 | 5273篇 |
国内免费 | 4114篇 |
专业分类
耳鼻咽喉 | 349篇 |
儿科学 | 484篇 |
妇产科学 | 567篇 |
基础医学 | 6538篇 |
口腔科学 | 1026篇 |
临床医学 | 7812篇 |
内科学 | 8041篇 |
皮肤病学 | 495篇 |
神经病学 | 2826篇 |
特种医学 | 2041篇 |
外国民族医学 | 42篇 |
外科学 | 5330篇 |
综合类 | 10350篇 |
现状与发展 | 19篇 |
一般理论 | 1篇 |
预防医学 | 3735篇 |
眼科学 | 1776篇 |
药学 | 6137篇 |
39篇 | |
中国医学 | 3496篇 |
肿瘤学 | 4671篇 |
出版年
2024年 | 225篇 |
2023年 | 1030篇 |
2022年 | 2526篇 |
2021年 | 3254篇 |
2020年 | 2330篇 |
2019年 | 1887篇 |
2018年 | 2119篇 |
2017年 | 1791篇 |
2016年 | 1749篇 |
2015年 | 2730篇 |
2014年 | 3365篇 |
2013年 | 2770篇 |
2012年 | 4158篇 |
2011年 | 4665篇 |
2010年 | 2692篇 |
2009年 | 2237篇 |
2008年 | 2844篇 |
2007年 | 2855篇 |
2006年 | 2863篇 |
2005年 | 2852篇 |
2004年 | 1882篇 |
2003年 | 1748篇 |
2002年 | 1501篇 |
2001年 | 1200篇 |
2000年 | 1278篇 |
1999年 | 1335篇 |
1998年 | 896篇 |
1997年 | 841篇 |
1996年 | 652篇 |
1995年 | 613篇 |
1994年 | 515篇 |
1993年 | 313篇 |
1992年 | 393篇 |
1991年 | 311篇 |
1990年 | 289篇 |
1989年 | 241篇 |
1988年 | 225篇 |
1987年 | 172篇 |
1986年 | 143篇 |
1985年 | 105篇 |
1984年 | 46篇 |
1983年 | 42篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 15篇 |
1979年 | 15篇 |
1977年 | 2篇 |
1973年 | 2篇 |
1935年 | 4篇 |
1910年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Gonadotropin-releasing hormone (GnRH) neurons are mainly located in the anterior preoptic area (aPOA) and gamma-aminobutyric acid (GABA) is known as a potent regulator of the GnRH neurons. To examine the development of the GABAergic system in the aPOA, immunocytochemistry of glutamic acid decarboxylase 67 (GAD(67)) was performed in immature (postnatal d16, d25 and d30) and mature (postnatal 10 weeks) male rats. All immunocytochemical procedures were simultaneously performed. In the lateral part of the aPOA, the detectable number of GAD(67)-immunoreactive cells was small in the d16 group, but significantly increased in the d25, d30 and mature groups, up to 2.7, 4.8 and 5.7 times the number in the d16 group, respectively. In the diagonal band of Broca (DBB), the number was also small in the d16 group, and significantly increased in the d25, d30 and mature groups upto 1.8, 2.2 and 2.8 times the number in the d16 group, respectively. However, in the cingulate cortex, no significant developmental change was observed. These results suggest that the development of the GABAergic system in the lateral aPOA and the DBB occurs before sexual maturation of male rats. 相似文献
82.
83.
Muda M He C Martini PG Ferraro T Layfield S Taylor D Chevrier C Schweickhardt R Kelton C Ryan PL Bathgate RA 《Molecular human reproduction》2005,11(8):591-600
LGR7 and LGR8 are G protein-coupled receptors that belong to the leucine-rich repeat-containing G-protein coupled receptor (LGR) family, including the thyroid-stimulating hormone (TSH), LH and FSH receptors. LGR7 and LGR8 stimulate cAMP production upon binding of the cognate ligands, relaxin and insulin-like peptide 3 (INSL3), respectively. We cloned several novel splice variants of both LGR7 and LGR8 and analysed the function of four variants. LGR7.1 is a truncated receptor, including only the N-terminal region of the receptor and two leucine rich repeats. In contrast, LGR7.2, LGR7.10 and LGR 8.1 all contain an intact seven transmembrane domain and most of the extracellular region, lacking only one or two exons in the ectodomain. Our analysis demonstrates that although LGR7.10 and LGR8.1 are expressed at the cell surface, LGR7.2 is predominantly retained within cells and LGR7.1 is partially secreted. mRNA expression analysis revealed that several variants are co-expressed in various tissues. None of these variants were able to stimulate cAMP production following relaxin or INSL3 treatment. Unexpectedly, we did not detect any direct specific relaxin or INSL3 binding on any of the splice variants. The large number of receptor splice variants identified suggests an unforeseen complexity in the physiology of this novel hormone-receptor system. 相似文献
84.
根据下頜光弹的等倾线图,描绘出主应力迹线规迹。在下颌侧位X线照片和去除唇侧及颊侧密质骨板的标本上,观察骨密质和松质的配布,以及骨小梁的排列和方向,试行探讨骨小梁方向与主应力迹线的关系。用光弹法求得的主应力迹线有两个系列:S_1系在下颌体近水平方向,在下颌支近垂直方向分布;S_2系力线与S_1系诸力线呈正交。在标本和X线照片上,主应力迹线规迹不同程度地在骨小梁的排列上有所反映。 相似文献
85.
Kinetics of the phenotype and function of murine peritoneal macrophages following acute inflammation 总被引:2,自引:0,他引:2
Wu Q Feng Y Yang Y Jingliu Zhou W He P Zhou R Li X Zou J 《Cellular & molecular immunology》2004,1(1):57-62
This study was undertaken to have a better understand for the process and the underlying mechanisms to limitmacrophage activation and population of activated macrophages.A comprehensive kinetics of cytokineproduction was performed in murine peritoneal macrophages recovered from Balb/c mice at various timeduring the course of an intraperitoneal injection with thioglycollate (TG).The expression of cell surfacemolecules such as MHC-Ⅰ,MHC-Ⅱ,B7-1 and B7-2 of these macrophages were also determined by flowcytometry.The present findings of our research suggested that the population of activated macrophages and theactivation of macrophages (including cytokines production and expression of cell surface functional molecules)were strictly controlled during inflammation process.This is one of the important mechanisms to retain the hosthomeostasis.Cellular & Molecular Immunology.2004;1(1):57-62. 相似文献
86.
Bi-directional modulation of T cell-dependent antibody production by prostaglandin E(2). 总被引:1,自引:0,他引:1
Xiaowen He Cornelia M Weyand J?rg J Goronzy Wanyun Zhong John M Stuart 《International immunology》2002,14(1):69-77
T cell-dependent Ig production involves interaction between T cells and B cells. This study evaluated the effects of prostaglandin (PG) E(2) on Ig production in a system in which B cells were co-cultured with autologous CD4(+) T cell clones non-specifically activated by anti-CD3. The effects of PGE(2) on T cell-dependent Ig production differed substantially, depending on the T cells employed. We selected six T cell clones that were able to enhance Ig production (resistant T cell clones) and six T cell clones that inhibited Ig production in the presence of PGE(2) (sensitive T cell clones) for comparison. The resistant T cells produced high levels (>1000 pg/ml) of IL-2 and/or IL-4, and expressed high CD40L, OX40 and CD45RA, and low CD45RO. In contrast, sensitive T cells secreted low IL-2 (<500 pg/ml) and IL-4 (<200 pg/ml), and expressed low CD40, OX40 and CD45RA, and high CD45RO. Adding supernatant derived from resistant T cell clones restored Ig production inhibited by PGE(2), while removing IL-2, IL-4 or IL-10 using specific antibodies inhibited Ig production. In addition, we demonstrated a direct effect of PGE(2) on B cells to enhance Ig production. Consistently, in the presence of resistant T cells, PGE(2) increased B cell proliferation and differentiation. In conclusion, the effects of PGE(2) on Ig production consist of its indirect effects through T cells and its direct effects on B cells. The outcome of the effects can be up-regulatory or down-regulatory, depending whether resistant or sensitive T cells are involved. 相似文献
87.
88.
The protease genes of Bacillus subtilis. 总被引:2,自引:0,他引:2
89.
90.
目的:为选择性脊髓血管造影和椎管内显微外科提供解剖学资料。方法:采用尸体标本30例,于节段性动脉内逐一注入红色乳胶,在完整脊髓上解剖观察。结果:每例脊髓胸腰段的后髓动脉数目5~13支,平均8.4支。后髓动脉起始情况分3型10亚型,其中后髓动脉与前髓动脉由同一肋间后动脉发出仅34支(13.5%)。胸下部及腰部后髓动脉呈典型“发卡”样折曲。后髓动脉平均外径0.37±0.12mm。约1/3标本在T_(11)~L_3间有1支后髓动脉较粗(>0.5mm),它是脊髓后下部血供的主要来源。结论:多数后髓动脉单独起始,较大的后髓动脉应引起注意。 相似文献