全文获取类型
| 收费全文 | 30888篇 |
| 免费 | 2838篇 |
| 国内免费 | 1427篇 |
专业分类
| 耳鼻咽喉 | 247篇 |
| 儿科学 | 341篇 |
| 妇产科学 | 317篇 |
| 基础医学 | 3841篇 |
| 口腔科学 | 496篇 |
| 临床医学 | 4059篇 |
| 内科学 | 4831篇 |
| 皮肤病学 | 266篇 |
| 神经病学 | 1549篇 |
| 特种医学 | 1100篇 |
| 外国民族医学 | 21篇 |
| 外科学 | 3185篇 |
| 综合类 | 4599篇 |
| 现状与发展 | 9篇 |
| 一般理论 | 4篇 |
| 预防医学 | 1825篇 |
| 眼科学 | 743篇 |
| 药学 | 2918篇 |
| 41篇 | |
| 中国医学 | 1590篇 |
| 肿瘤学 | 3171篇 |
出版年
| 2025年 | 38篇 |
| 2024年 | 613篇 |
| 2023年 | 718篇 |
| 2022年 | 1362篇 |
| 2021年 | 1802篇 |
| 2020年 | 1365篇 |
| 2019年 | 1265篇 |
| 2018年 | 1077篇 |
| 2017年 | 933篇 |
| 2016年 | 895篇 |
| 2015年 | 1398篇 |
| 2014年 | 1720篇 |
| 2013年 | 1356篇 |
| 2012年 | 2036篇 |
| 2011年 | 2273篇 |
| 2010年 | 1382篇 |
| 2009年 | 1098篇 |
| 2008年 | 1423篇 |
| 2007年 | 1487篇 |
| 2006年 | 1408篇 |
| 2005年 | 1534篇 |
| 2004年 | 907篇 |
| 2003年 | 806篇 |
| 2002年 | 763篇 |
| 2001年 | 635篇 |
| 2000年 | 634篇 |
| 1999年 | 707篇 |
| 1998年 | 523篇 |
| 1997年 | 477篇 |
| 1996年 | 402篇 |
| 1995年 | 364篇 |
| 1994年 | 289篇 |
| 1993年 | 165篇 |
| 1992年 | 233篇 |
| 1991年 | 178篇 |
| 1990年 | 147篇 |
| 1989年 | 136篇 |
| 1988年 | 153篇 |
| 1987年 | 101篇 |
| 1986年 | 96篇 |
| 1985年 | 71篇 |
| 1984年 | 41篇 |
| 1983年 | 34篇 |
| 1982年 | 28篇 |
| 1981年 | 22篇 |
| 1980年 | 10篇 |
| 1979年 | 18篇 |
| 1978年 | 5篇 |
| 1971年 | 5篇 |
| 1969年 | 5篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
991.
Clinical studies demonstrate that prenatal stress causes cognitive deficits and increases vulnerability to affective disorders in children and adolescents. The underlying mechanisms are not yet fully understood. Here, we reported that prenatal stress (10 unpredictable, 1 s, 0.8 mA foot shocks per day during gestational days 13-19) impaired long-term potentiation (LTP) but facilitated long-term depression (LTD) in hippocampal CA1 region in slices of the prenatal stressed offspring (5 weeks old). Cross-fostering neonate offspring by the prenatal stressed or control mothers did not change the effects of prenatal stress on the hippocampal LTP and LTD. Furthermore, prenatal stress enhanced the effects of acute stress on the hippocampal LTP and LTD and impaired spatial learning and memory in the Morris water maze in the young rat offspring. Therefore, prenatal stress alters synaptic plasticity and enhances the effects of acute stress on synaptic plasticity in the hippocampus, which may be the mechanism for the impaired spatial learning and memory in young rat offspring. 相似文献
992.
Learned association between drugs of abuse and context is essential for the formation of drug conditioned place preference (CPP), which is believed to engage many brain regions including hippocampus and nucleus accumbens (NAc). The underlying mechanisms are not fully understood. Here, we examined whether glucocorticoid receptors (GRs) of hippocampus and NAc influenced the formation of morphine CPP in Sprague Dawley rats. We found that systemic or intrahippocampal infused DMSO vehicle (DMSO 20% in saline) 30 min before daily morphine (10 mg/kg, s.c.) conditioning did not affect the formation of morphine CPP. In contrast, systemic administration (5 mg/kg, s.c.) or intrahippocampal infusion (0, 0.1, 1.0, 10, 20 microg per side) of the GR antagonist RU38486 blocked or impaired the formation of CPP in a dose-dependent manner, respectively. Furthermore, intra-NAc infused RU38486 (10 microg per side) but not DMSO vehicle also prevented the formation of CPP. These results demonstrate that both the GRs of hippocampus and NAc are necessary for the formation of morphine CPP, suggesting a neural network function of the GRs in forming the opiate-associated memory. 相似文献
993.
Q.‐Z. Fei W.‐G. Tang T.‐Y. Rong H.‐D. Tang J.‐R. Liu Z.‐L. Guo Y. Fu Q. Xiao X.‐J. Wang S.‐B. He L. Cao S.‐D. Chen 《European journal of neurology》2011,18(9):1194-1196
Background and purpose: Hereditary spastic paraplegia (HSP) is a clinically and genetically heterogeneous group of neurodegenerative diseases. Mutations in the spastin (SPG4) gene are responsible for approximately 40% of autosomal dominant HSP (AD‐HSP) and 6.5–18% of sporadic cases. Methods: Spastin mutations were screened in 11 AD‐HSP families and 11 sporadic cases by direct sequencing and MLPA assay. Novel mutations were detected in 100 healthy controls by PCR‐RFLP. Results: We identified seven different spastin mutations in five probands and one sporadic patient. Two of seven mutations were novel. The c.458delT was a pathogenic mutation, but the effect of c.1724 G>T remained unknown. Conclusions: This study allowed us to estimate the frequency of the SPG4 mutations in Chinese at 45% (5/11) in families with AD‐HSP and 9% (1/11) in sporadic cases. In addition, our data showed p.T614I was not associated with congenital arachnoid cysts. 相似文献
994.
陈盛强 Kaiyi Cao Lijun Dai Weiwen Sun Xi Chen Yueling Huang Chen xi 易咏红 Xuegang Luo Quan Yang 《中国神经再生研究》2011,6(31):2452-2459
In the present study,Fmr1 knockout mice (KO mice) were used as the model for fragile X syndrome.The results of step-through and step-down tests demonstrated that Fmr1 KO mice had shorter latencies and more error counts,indicating a learning and memory disorder.After treatment with 30,60,90,120,or 200 mg/kg lithium chloride,the learning and memory abilities of the Fmr1 KO mice were significantly ameliorated,in particular,the 200 mg/kg lithium chloride treatment had the most significant effect.Western blot analysis showed that lithium chloride significantly enhanced the expression of phosphorylated glycogen synthase kinase 3 beta,an inactive form of glycogen synthase kinase 3 beta,in the cerebral cortex and hippocampus of the Fmr1 KO mice.These results indicated that lithium chloride improved learning and memory in the Fmr1 KO mice,possibly by inhibiting glycogen synthase kinase 3 beta activity. 相似文献
995.
背景：等速测试系统已广泛应用来评价不同项目运动员关节肌群的力量特征。目的：测试广东省女子曲棍球运动员的膝关节进行等速向心,观察曲棍球项目运动员膝关节屈伸肌群的等速向心测试力量特征。方法：运用CON-TREX等速测试系统对广东省14名现役女子曲棍球运动员的膝关节进行等速向心测试。检测指标为相对峰力矩、关节肌群屈伸肌峰力矩比值、平均功率、总功和疲劳指数。结果与结论：在60 (°/s)慢速测试时,女子曲棍球队员的两侧膝关节肌群相对峰力矩值表现为伸肌大于屈肌(P < 0.01);左膝关节屈伸肌峰力矩比值在3种不同测试速度下的范围为66%~77%,右膝关节屈伸肌峰力矩比值为82%~88%;左膝关节伸肌平均功率值均大于屈肌(P < 0.01);左右膝关节伸肌的总功值均大于屈肌(P < 0.01);膝关节屈伸肌疲劳指数范围在0.24~0.48之间。膝关节伸肌的最大力量大于屈肌,屈伸肌峰力矩比值在240 (°/s)快速测试时略微偏低,而右膝关节屈伸肌峰力矩比值在慢速测试时偏高,说明女子曲棍球队员左膝关节屈肌快速力量偏低,右膝关节伸肌最大力量比较低,伸肌的快速力量大于屈肌,伸肌的工作能力强于屈肌,屈伸肌的力量耐力水平比较低。 相似文献
996.
背景: 临床上肾移植后贫血发生率为30%~40%,是肾移植后心血管疾病和移植肾失功的重要危险因素,并且是患者死亡的独立预测指标。目的：分析肾移植后贫血发生的相关因素。方法：分析2000-01/2009-12解放军沈阳军区总医院肾移植826例患者资料,其中男541例,女285例,年龄17~71岁;尸体供肾805例,亲体活体供肾21例。根据移植后是否发生贫血将患者分成贫血组与非贫血组,记录可能引起移植后贫血的各项参数,分别用t检验和卡方检验进行单因素分析。结果与结论：826例肾移植患者中发生贫血225例,发生率为27.2%。女性和男性患者贫血发生率分别为23%和37%(P < 0.05 );年龄26~65岁,其中伴有高血压应用血管紧张素转化酶抑制剂或血管紧张素Ⅱ受体拮抗剂类降压药物者46例, 伴有慢性糜烂性胃炎或上消化道溃疡者16例,人存活率为85.3%,肾失功率为25.3%;非贫血组601例,占总例数的72.8%,其中男405例,女196例,年龄17~71岁,伴有高血压应用血管紧张素转化酶抑制剂或血管紧张素Ⅱ受体拮抗剂降压药物者35例,伴有慢性糜烂性胃炎或上消化道溃疡者14例,人存活率为92.1%,肾失功率为12.6%,与贫血组对比差异有显著性意义(P < 0.05)。分析表明,性别、年龄、肾功能、消化道疾病史、药物因素等与肾移植后贫血的发生密切相关。 相似文献
997.
Cao JP Yu JK Li C Sun Y Yuan HH Wang HJ Gao DS 《The Journal of comparative neurology》2008,509(2):203-210
Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor for the substantia nigra (SN) dopamine (DA) neurons. The transmembrane signaling of GDNF is mediated by a unique receptor system, including the ligand binding receptor GDNF family receptor alpha (GFRalpha) and the transmembrane signaling receptor Ret or neural cell adhesion molecule-140 (NCAM-140). Here, we found that another transmembrane cell adhesion molecule, integrin, a heterodimer consisting of alpha and beta subunits, also mediates the transmembrane signaling of GDNF. The results showed that the level of phosphorylated Src homology 2 domain containing (Shc), which was associated with the cytoplasmic domain of integrin beta1, increased after GDNF administration. Coimmunoprecipitation analysis demonstrated that integrin beta1 could form a complex with GFRalphal. The simulation of molecular modeling showed that four H-bonds were formed between integrin beta1 and GFRalpha. These data indicate that integrin beta1 is involved in the transmembrane signaling of GDNF and suggest that integrin beta1 may be an alternative signaling receptor for GDNF. 相似文献
998.
Mutations in the gene that encodes espins can cause deafness and vestibular disorders; mice that are homozygous for the autosomal recessive jerker mutation in the espin gene never hear. Extracellular injections of biocytin into the anteroventral cochlear nucleus (AVCN) revealed that although the cochlear nuclei are smaller in je/je mice, the topography in its innervation resembles that in wild-type mice. Auditory nerve fibers innervate narrow, topographically organized, \"isofrequency\" bands in deaf animals over the ages examined, P18-P70. The projection of tuberculoventral cells was topographic in je/je as in wild-type mice. Terminals of auditory nerve fibers in the multipolar cell area included both large and small endings, whereas in the octopus cell area they were exclusively small boutons in je/je as in wild-type mice, but end bulbs near the nerve root of je/je animals were smaller than in hearing animals. In whole-cell recordings from targets of auditory nerve fibers, octopus and T stellate cells, miniature excitatory postsynaptic currents (mEPSCs) had similar shapes as in +/+, indicating that the properties of AMPA receptors were not affected by the mutation. In je/je animals the frequency of spontaneous mEPSCs was elevated, and synaptic depression in responses to trains of shocks delivered at between 100 and 333 Hz was greater than in wild-type mice, indicating that the probability of neurotransmitter release was increased. The frequency of spontaneous mEPSCs and extent of synaptic depression were greater in octopus than in T stellate cells, in both wild-type and in je/je mice. 相似文献
999.
With the development of interventional therapy, it is necessary for evaluating cerebral vessels to instruct treatment and determine prognosis of patients with ischemic stroke; however, correlation of distribution of infarction focus and clinical symptoms with degrees of cerebrovasoular stricture is still unclear.OBJECTIVE: To evaluate the characteristics of cerebral arterial stricture of patients with ischemic stroke with transcranial Doppler (TCD) and color duplex flow imaging (CDFI) and compare the correlation between distribution of cerebral infarction focus and clinical types with magnetic resonance imaging (MRI).DESIGN: Contrast observation.SETTING: Department of Neurology, the First Hospital of Jilin University.PARTICIPANTS: A total of 159 patients with ischemic stroke were selected from the Department of Neurology, the First Hospital of Jilin University from January to December 2005, including 106 males and 53 females aged from 27 to 88 years. Bases on diagnostic criteria of cerebrovascular disease established by Rao et al, clinical manifestations of all patients were evaluated with CT or nuclear magnetic resonance. All patients provided the confirmed consent.METHODS: The accepted patients received TCD and CDFI examination at 1 week after onset of ischemic stroke. Among them, 112 patients received cerebrovascular imaging examination simultaneously. MRI was used to check cerebral infarction focus and cerebrovascular stricture ＞ 50% was regarded as the accepted vessels. In addition, DWI-T2 TCD (Germany) was used to check middle cerebral artery, and degrees of middle cerebral artery were classified into mild, moderate and severe stricture based on blood velocity (140 cm/s,180 cm/s). Stroke was classified based on characteristics of infarction focus and clinical symptoms showed with MRI and correlation with degrees of cerebrovascular stricture was analyzed simultaneously.MAIN OUTCOME MEASURES: Correlation between the characteristics of ischemic stroke and clinical symptoms checked with TCD and CDFI.RESULTS: A total of 159 patients with ischemic stroke were involved in the final analysis; in addition, 112 oases received cerebrovascular imaging examination simultaneously. ① MRI results of 159 patients with cerebral artery occlusive disease (CAOD): There were 131 patients (82.3%) with cerebral infarction, 40 (25.2%)with transient ischemic attack and 4 (2.5%) with subclavian steal syndrome (SSS). ② Infarction types with MRI examination: There were 33 patients (20.8%) with solitary cerebral infarction and 98 (61.6%) with multiple-cerebral infarction. ③ Results of TCD, CDFI, MRI angiography, CT angiography and digital subtraction angiography (DSA): Among 112 patients, 181 lesion sites (61 .8%) were located in cranium and 112 lesion sites were located out of cranium; especially, lesion site was mostly observed in stem of middle cerebral artery (31.2%) and watershed of basilar artery (7.2%) in cranium and the beginning site of internal carotid artery (21 .4%) out of cranium. ④ Correlation of vascular stricture checking with TCD, MRI and clinical diagnosis: On one hand, MRI and clinical diagnosis demonstrated that 68 patients had a watershed infarction; meanwhile,TCD examination indicated that there were 3 patients with mild vascular stricture, 24 with moderate vascular stricture and 36 with severe vascular stricture. On the other hand, among 68 patients with non-watershed infarction, there were 27 patient with mild vascular stricture, 26 with moderate vascular stricture and 15 with severe vascular stricture. There were significant differences (x2 =26.854, P =0.001 ). Clinical diagnosis indicated that 40 patients had transient ischemic attack and TCD examination demonstrated that there were 8 patient with mild vascular stricture, 12 with moderate vascular stricture and 20 with severe vascular stricture. There were significant differences as compared with 68 patients with watershed infarction (x2 =21.258, P =0.001). ⑤Correlation of vascular stricture checking with CDFI, MRI and clinical diagnosis: On one hand, among patients who were determined as watershed infarction with MRI and clinical diagnosis, CDFI examination indicated that there were 32 patients with mild vascular stricture at neck, 25 with moderate vascular stricture and 6 with severe vascular stricture. On the other hand, among patients with non-watershed infarction, there were 48 patient with mild vascular stricture, 18 with moderate vascular stricture and 2 with severe vascular stricture.There were significant differences (x2 =6.018, P =0.019). Among patients with transient ischemic attack checking with clinical diagnosis, there were 23 patient with mild vascular stricture, 9 with moderate vascular stricture and 8 with severe vascular stricture. There were no significant differences as compared with patients with non-watershed infarction (x2 =0.597, P=0.440).CONCLUSION: ① TCD and CDFI are effective marks to determine cerebral arterial stricture and hemodynamical changes. ② Infarction and transient ischemic attack at watershed are generally clinical phenotypes of CAOD patients and infarction at watershed is correlated with degrees of cerebrovascular stricture.③ TCD, MRI and clinical analysis of stroke types are significant for instructing treatment and evaluate prognosis. 相似文献
1000.
Guang Yang Chen Huang Jun Cao Ke-Jian Huang Tao Jiang Zheng-Jun Qiu 《World journal of gastroenterology : WJG》2009,15(30):3757-3766