全文获取类型
收费全文 | 19209篇 |
免费 | 1675篇 |
国内免费 | 1398篇 |
专业分类
耳鼻咽喉 | 186篇 |
儿科学 | 154篇 |
妇产科学 | 247篇 |
基础医学 | 2280篇 |
口腔科学 | 213篇 |
临床医学 | 2296篇 |
内科学 | 3402篇 |
皮肤病学 | 189篇 |
神经病学 | 928篇 |
特种医学 | 717篇 |
外国民族医学 | 11篇 |
外科学 | 2051篇 |
综合类 | 3158篇 |
一般理论 | 2篇 |
预防医学 | 1084篇 |
眼科学 | 568篇 |
药学 | 2029篇 |
15篇 | |
中国医学 | 961篇 |
肿瘤学 | 1791篇 |
出版年
2024年 | 63篇 |
2023年 | 318篇 |
2022年 | 747篇 |
2021年 | 961篇 |
2020年 | 675篇 |
2019年 | 653篇 |
2018年 | 733篇 |
2017年 | 574篇 |
2016年 | 609篇 |
2015年 | 858篇 |
2014年 | 1048篇 |
2013年 | 869篇 |
2012年 | 1376篇 |
2011年 | 1514篇 |
2010年 | 863篇 |
2009年 | 721篇 |
2008年 | 1042篇 |
2007年 | 1007篇 |
2006年 | 976篇 |
2005年 | 960篇 |
2004年 | 644篇 |
2003年 | 595篇 |
2002年 | 518篇 |
2001年 | 459篇 |
2000年 | 513篇 |
1999年 | 455篇 |
1998年 | 344篇 |
1997年 | 303篇 |
1996年 | 269篇 |
1995年 | 258篇 |
1994年 | 171篇 |
1993年 | 125篇 |
1992年 | 166篇 |
1991年 | 158篇 |
1990年 | 127篇 |
1989年 | 123篇 |
1988年 | 112篇 |
1987年 | 99篇 |
1986年 | 95篇 |
1985年 | 61篇 |
1984年 | 29篇 |
1983年 | 23篇 |
1982年 | 11篇 |
1981年 | 17篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1974年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
One hundred and four male Sprague-Dawley rats were divided into three experiments. The first two experiments were to assess the effect of different MK-801 doses (0.1-0.3 mg/kg) and combinations of MK-801/ haloperidol (0.3/0.1-0.5 mg/kg) on locomotor behaviour. The animals from the third experiment were administered either saline, MK-801 (0.3 mg/kg), haloperidol (0.5 mg/kg) or MK-801/haloperidol (0.3/0.5 mg/kg). Locomotor activity measurements showed that the NMDA antagonist MK-801 induced a dose-dependent hyperactivity, while haloperidol, the D-2 dopamine receptor antagonist, induced hypoactivity. Significantly the highest doses of combined MK-801/haloperidol treatment (0.3/0.5 mg/kg) showed behavioural equivalence to the saline animals in both total locomotion, locomotion patterns and within-session habituation. Thus, the behavioural effects of each drug given alone were cancelled when the drugs were given together. This cancellation effect could not be ascribed to direct drug interference effects on dopamine metabolism since the ex vivo biochemical data revealed that the combined MK-801/haloperidol (0.3/0.5 mg/kg) treatment increased dopamine metabolism to the same extent as haloperidol given alone. None of the drug treatments, however, had any effect on brain serotonin metabolism. Serum measurement indicated that dopamine, homovanillic acid, 3,4-dihydroxyphenyl-acetic acid, 5-hydroxyindole-3-acetic acid, norepinephrine and corticosterone were not differentially affected by the drug treatment. Haloperidol-treated animals, however, had higher serum serotonin concentration than saline-treated animals. Taken together, these results support the hypothesis that the effect of MK-801 on behaviour is independent of biochemical changes in dopaminergic neuro transmission per se. Rather, the present results support the hypothesis of a glutamatergic-dopaminergic balance which when disturbed leads to behavioural changes along an excitatory-inhibitory behavioural gradient. 相似文献
34.
肺癌患者血浆GST-π水平测定及其临床意义 总被引:1,自引:0,他引:1
探讨肺癌患者手术和化疗前后血浆GST-π水平的变化。方法应用RIA方法对32例手术和26例化疗的肺癌患者进行动态检测。结果无论手术还是化疗前后患者血浆GST-π水平均明显高于正常对照组。 相似文献
35.
中国地鼠情绪唤醒水平评定量表的制定 总被引:1,自引:0,他引:1
为建立一套适合于中国地鼠情绪唤醒水平观测的评定方法,并验证其可靠性,在Ader 情绪唤醒评定方法基础上进行修订,对中国地鼠进行试测,建立情绪唤醒水平划界分。结果显示总分以5 分为界,能区分高/ 低情绪唤醒水平的中国地鼠;条目与量表总分呈中高度相关( r = 0 .3268 ~0 .7347) ,量表总分重测信度良好( r = 0 .5874 ~0 .6105) ,评定者评分一致性高,符合率达95-2 % 相似文献
36.
Dai Y Zhang S Yamamoto J Ao M Belin TR Cheung F Hifumi SS 《Community mental health journal》1999,35(6):537-542
There is a high prevalence of suicide amongelderly Chinese, and particularly among elderly Chinesewomen in Mainland China with a prevalence of 19.6 perhundred thousand. Since Chinese individuals may much more highly value education, acognitive-behavioral package originated by RicardoMunoz, Ph.D. was adapted for Chinese American subjects.The material was videotaped in eight sessions,approximately 25 minutes in length, to be shown to communitysubjects who were at least 40 years and over. Inaddition, a videotape of muscular relaxation techniqueswas made. A manual written in Chinese about the content of each class, was given to each subject whenhe/she attended. The experimental group showedsignificant improvement in the scores in the HamiltonDepression Scale, including the Somatic Subscale in the Hamilton Anxiety Scale. There was nosignificant improvement in the control group on any ofthe measures. Thus the study suggests the efficacy ofpsychoeducational classes in reducing symptoms ofdepression in non-patient community elderly. Other studiesare being conducted among Korean Americans and JapaneseAmericans in the United States, and also in the Orientamong Japanese elderly. 相似文献
37.
Expression of neurotrophins in the adult spinal cord in vivo 总被引:6,自引:0,他引:6
Dreyfus CF Dai X Lercher LD Racey BR Friedman WJ Black IB 《Journal of neuroscience research》1999,56(1):1-7
Potential roles of trophins in the normal and injured spinal cord are largely undefined. However, a number of recent studies suggest that adult spinal cord expresses neurotrophin receptors and responds to the neurotrophins, brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3), particularly after injury. The data indicate that trophins may enhance regrowth after damage and may represent a new therapeutic approach to injury. Neurotrophins are reportedly present in the spinal cord, but the cellular localization is unknown. This information is critical to begin delineating mechanisms of actions. To approach this problem, we examined whether spinal cord glia express BDNF and NT3 in vivo and have begun to define cellular distribution. Specific antibodies directed against the neurotrophins were utilized to visualize neurotrophin protein. Initial studies indicated that small cells in the white matter of adult rat spinal cord express BDNF and NT3. Large neurotrophin-positive neurons were also identified in the ventral cord. To identify the neurotrophin-positive cells, co-localization studies were performed utilizing neurotrophin polyclonal antisera together with monoclonal antibodies directed against the astrocyte marker, glial fibrillary acidic protein (GFAP). In the white matter of adult spinal cord, GFAP-positive and GFAP-negative cells expressed BDNF and NT3. Our study suggests that astrocyte and non-astrocyte cells provide trophic support to the adult spinal cord. 相似文献
38.
Gene cloning and sequencing of BmK AS and BmK AS-1, two novel neurotoxins from the scorpion Buthus martensi Karsch. 总被引:1,自引:0,他引:1
Based on the known amino acid sequences of BmK AS and BmK AS-1, the gene specific primers were designed and synthesized for 3' and 5' RACE (Rapid Amplification of cDNA Ends). Their partial cDNA fragments obtained by 3' and 5' RACE were cloned and sequenced, and the full length cDNA sequences of BmK AS and BmK AS-1 were then completed by overlapping their two partial cDNA sequences, respectively. The predicted amino acid sequences both consist of 85 amino acid residues including a putative signal peptide of 19 residues and a mature toxin of 66 residues. They are different in 17 amino acid residues, among them 11 residues in the mature toxin. The predicted amino acid sequences of BmK AS and BmK AS-1 were almost consistent with those determined and revised (personal communication), only different in one and two residues at their COO-terminal parts, respectively. Based on the determined cDNA sequences, and using the total DNAs isolated from the scorpion venom glands as a template, the genomic DNAs of BmK AS and BmK AS-1 were also amplified by PCR and sequenced. It showed that no intron was inserted in their open reading frames, while in the exon of signal peptide sequences of other Na+, K+ and Cl- channel toxins from the same scorpion, an intron is usually found. However, the Northern blot hybridization results indicated that the sizes of their mRNA should be around 800 bp. Their extra sequences around 400 bp which might function as an intron should be located at their 5' untranslated regions. 相似文献
39.
左旋四氢巴马汀对单个豚鼠心室肌细胞钙电流的阻滞作用 总被引:4,自引:0,他引:4
AIM: To study the effect of l-tetrahydropalmatine (l-THP) on L-type calcium channel. METHODS: Patch clamp technique (whole cell recording) was used to record L-Ca2+ current in single cardiac myocyte. RESULTS: 1) l-THP 1, 10, and 100 micromol.L-1 reduced ICa-max from (999 +/- 93) pA to (700 +/- 111) pA, (582 +/- 66) pA, and (420 +/- 112) pA (n = 6, P < 0.01), respectively. 2) l-THP reduced the voltage at half-maximal inactivation (V1/2) of L-Ca2+ channel to more negative potentials by 9 mV (n = 5, P < 0.05). 3) l-THP caused both tonic and use-dependent reduction of Ca2+ current. Tonic block of l-THP on Ca2+ current was 46% +/- 8% (n = 6, P < 0.01). The degree of use dependent blocking was 13.5% +/- 2.4% (n = 6, P < 0.05) at 1 Hz, the degree increased to 44% +/- 5% (n = 6, P < 0.01) at 3 Hz. 4) l-THP delayed half-recovery time of Ca2+ channel recovery from inactivity from (94 +/- 39) ms to (170 +/- 42) ms(n = 6, P < 0.01). CONCLUSION: l-THP has a moderate inhibitory effect on L-Ca2+ current. 相似文献
40.
Facilitating effect of histamine on spatial memory deficits induced by dizocilpine as evaluated by 8-arm radial maze in SD rats 总被引:3,自引:3,他引:3
HUANG Yu-Wen CHEN Zhong~ HU Wei-Wei ZHANG Li-San WU Wei YING Li-Yang WEI Er-Qing Department of Neurobiology Pharmacology School of Medicine Zhejiang University Hangzhou China 《Acta pharmacologica Sinica》2003,(12)
AIM: To investigate whether or not histamine is involved in spatial memory deficits induced by dizocilpine (MK-801) as evaluated by 8-arm radial maze of rats. METHODS: 8-Arm (4-arm baited) radial maze was used to measure spatial memory in rats. RESULTS: Bilaterally intrahippocampal (ih) injection of MK-801 (0.3 μg/site) impaired working memory and reference memory in rats. Both histamine (50, 100 ng/site, ih) and intraperitoneal (ip) injection of histidine (100, 200 mg/kg) markedly improved the spatial memory deficits induced by MK-801. On the other hand, the ameliorating effect of histidine (100 mg/kg, ip) was completely antagonized by α-fluoromethylhistidine (α-FMH, 5 μg/site, ih), a potent and selective histidine decarboxylase (HDC) inhibitor, and H_1-antagonist pyrilamine (1 μg/site, ih), but not by H_2-antagonist cimetidine, even at a high dose (2.5 μg/site, ih). CONCLUSION: The hippocampal histamine plays an important role in the ameliorating effect on MK-801-induced spatial memory deficits, 相似文献