全文获取类型
收费全文 | 18646篇 |
免费 | 1461篇 |
国内免费 | 893篇 |
专业分类
耳鼻咽喉 | 62篇 |
儿科学 | 760篇 |
妇产科学 | 213篇 |
基础医学 | 1812篇 |
口腔科学 | 67篇 |
临床医学 | 1560篇 |
内科学 | 3399篇 |
皮肤病学 | 72篇 |
神经病学 | 892篇 |
特种医学 | 669篇 |
外国民族医学 | 3篇 |
外科学 | 2453篇 |
综合类 | 2977篇 |
现状与发展 | 3篇 |
预防医学 | 1145篇 |
眼科学 | 212篇 |
药学 | 2165篇 |
7篇 | |
中国医学 | 1266篇 |
肿瘤学 | 1263篇 |
出版年
2024年 | 41篇 |
2023年 | 340篇 |
2022年 | 540篇 |
2021年 | 816篇 |
2020年 | 613篇 |
2019年 | 627篇 |
2018年 | 592篇 |
2017年 | 637篇 |
2016年 | 679篇 |
2015年 | 703篇 |
2014年 | 1191篇 |
2013年 | 1345篇 |
2012年 | 1111篇 |
2011年 | 1170篇 |
2010年 | 925篇 |
2009年 | 909篇 |
2008年 | 841篇 |
2007年 | 882篇 |
2006年 | 804篇 |
2005年 | 668篇 |
2004年 | 583篇 |
2003年 | 562篇 |
2002年 | 430篇 |
2001年 | 397篇 |
2000年 | 337篇 |
1999年 | 286篇 |
1998年 | 258篇 |
1997年 | 245篇 |
1996年 | 223篇 |
1995年 | 234篇 |
1994年 | 232篇 |
1993年 | 200篇 |
1992年 | 161篇 |
1991年 | 143篇 |
1990年 | 135篇 |
1989年 | 136篇 |
1988年 | 118篇 |
1987年 | 90篇 |
1986年 | 79篇 |
1985年 | 109篇 |
1984年 | 84篇 |
1983年 | 79篇 |
1982年 | 80篇 |
1981年 | 73篇 |
1980年 | 70篇 |
1979年 | 55篇 |
1978年 | 32篇 |
1977年 | 33篇 |
1976年 | 28篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Xiumei Jiang Xiaowei Zhang Patrick Gray Jiwen Zheng Timothy R. Croley Peter P. Fu 《journal of environmental science and health part c-environmental carcinogenesis & ecotoxicology reviews》2019,37(2):116-131
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability. 相似文献
2.
目的:研究Toll样受体4(TLR4) mRNA及其下游炎性因子肿瘤坏死因子-α(TNF-α)与肝衰竭肠源性内毒素血症(IETM)大鼠肝细胞凋亡的关系,并探索温阳解毒化瘀颗粒对内毒素介导的肝细胞凋亡的调控机制。方法:SPF级雄性SD大鼠85只,随机分为正常组,模型组,TLR4单克隆抗体组和温阳解毒化瘀颗粒组(8.925 g·kg^-1)。采用D-半乳糖胺(D-Gal)腹腔注射建立肝衰竭IETM模型,TLR4单克隆抗体组和温阳解毒化瘀颗粒组在造模前5 d给予温阳解毒化瘀颗粒溶液灌胃,正常组、模型组以等容积蒸馏水代替,直至处死。各组分别在24,48,72 h随机处死大鼠并采集标本。检测24,48,72 h各组时间点血清丙氨酸氨基转移酶(ALT),天门冬氨酸氨基转移酶(AST)水平,苏木素-伊红(HE)染色观察肝组织病理变化,实时荧光定量聚合酶链式反应(Real-time PCR)检测肝组织TLR4 mRNA表达,酶联免疫吸附测定法(ELISA)检测肝组织TNF-α表达,流式细胞仪检测肝细胞凋亡率。结果:与正常组比较,模型组ALT,AST升高,肝组织病理损伤程度明显加重,TLR4mRNA,TNF-α表达均增高(P<0.05,P<0.01),肝细胞凋亡率明显上升(P<0.05,P<0.01);与模型组比较,温阳解毒化瘀颗粒组ALT,AST显著降低(P<0.01),肝组织病理损伤程度明显减轻(P<0.05),TLR4 mRNA,TNF-α表达显著下降(P<0.01),肝细胞凋亡率亦显著降低(P<0.01)。结论:TLR4 mRNA,TNF-α在肝衰竭时与肝细胞凋亡呈正相关,温阳解毒化瘀颗粒能够改善肝衰竭IETM大鼠肝功能,减轻肝细胞损伤,减少肝细胞凋亡,其机制可能与其下调肝脏TLR4 mRNA表达,抑制TNF-α释放,降低肝细胞凋亡率有关。 相似文献
3.
4.
5.
Aaron Pitzele Mohammad Rahimi Eric Armbrecht 《The journal of maternal-fetal & neonatal medicine》2015,28(15):1770-1773
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion. 相似文献
6.
7.
8.
《European journal of medical genetics》2020,63(4):103825
BackgroundThe collagen type IV alpha 1 chain (COL4A1) is an essential component of the basement membrane in small vessels. Pathogenic variants in COL4A1 cause perinatal cerebral hemorrhages in an autosomal-dominant fashion. However, little is known about the long-term outcomes of patients with mildly affecting COL4A1 mutations.Case reportWe report a 17-year-old boy, who presented with recurrent intracranial hemorrhages in the periventricular white matter. He had been followed-up as a child with cerebral palsy bearing intracranial calcifications, developmental delay and epilepsy. Screening tests in infancy provided negative results for intrauterine infections. Severe motor and cognitive deficits persisted after admission. Carbazochrome was introduced on day 19 of admission, which appeared to prevent extension and reactivation of cerebral hemorrhages for over 6 months after discharge.ResultsTargeted sequencing of NOTCH3 and TREX1 excluded causal mutations in these genes. The whole-exome sequencing revealed that he carried a de novo mutation in COL4A1 (p.Gly696Ser). An overview of the literature for 345 cases with COL4A1 mutations supported evidence that p.Gly696Ser is associated with the unique phenotype of late-onset hemorrhage among patients with COL4A1-associated cerebral angiopathy.ConclusionsThis case first demonstrates that infants with COL4A1-associated leukoencephalopathy and calcifications have a risk for developing the rupture of small vessels in the cerebral white matter after 10 years of age. 相似文献
9.
目的观察胆道结石合并糖尿病患者腹腔镜胆囊切除术(LC)后肠屏障功能的变化。方法将择期行LC的126例患者分为糖尿病组41例和非糖尿病组85例。术前及术后第1、3天,采用高效液相色谱法检测尿乳果糖与甘露醇比值(L/M),并采用酶联免疫吸附法(ELISA)检测尿脂肪酸结合蛋白(IFABP)及血清D-乳酸水平。结果2组患者均成功完成手术,无中转开放手术者。糖尿病组术后肛门排气时间长于非糖尿病组,差异有统计学意义(P<0.05)。糖尿病组术后第1、3天尿L/M、血清D-乳酸、尿IFABP均高于术前及非糖尿病组,差异均有统计学意义(P<0.05)。结论合并糖尿病的胆道结石患者行LC后会加重肠屏障功能障碍程度,术前控制好血糖水平或可降低肠道功能损伤的严重程度。 相似文献
10.