全文获取类型
收费全文 | 49872篇 |
免费 | 3717篇 |
国内免费 | 1554篇 |
专业分类
耳鼻咽喉 | 285篇 |
儿科学 | 917篇 |
妇产科学 | 466篇 |
基础医学 | 7602篇 |
口腔科学 | 642篇 |
临床医学 | 2584篇 |
内科学 | 6566篇 |
皮肤病学 | 1004篇 |
神经病学 | 5227篇 |
特种医学 | 683篇 |
外国民族医学 | 5篇 |
外科学 | 4191篇 |
综合类 | 4802篇 |
现状与发展 | 2篇 |
预防医学 | 2307篇 |
眼科学 | 579篇 |
药学 | 10669篇 |
6篇 | |
中国医学 | 1852篇 |
肿瘤学 | 4754篇 |
出版年
2024年 | 117篇 |
2023年 | 1015篇 |
2022年 | 2081篇 |
2021年 | 2029篇 |
2020年 | 1602篇 |
2019年 | 1998篇 |
2018年 | 1803篇 |
2017年 | 1662篇 |
2016年 | 1352篇 |
2015年 | 1625篇 |
2014年 | 2471篇 |
2013年 | 2971篇 |
2012年 | 2445篇 |
2011年 | 2929篇 |
2010年 | 2501篇 |
2009年 | 2405篇 |
2008年 | 2405篇 |
2007年 | 2212篇 |
2006年 | 2030篇 |
2005年 | 1697篇 |
2004年 | 1602篇 |
2003年 | 1411篇 |
2002年 | 1033篇 |
2001年 | 777篇 |
2000年 | 837篇 |
1999年 | 690篇 |
1998年 | 709篇 |
1997年 | 638篇 |
1996年 | 553篇 |
1995年 | 512篇 |
1994年 | 444篇 |
1993年 | 428篇 |
1992年 | 420篇 |
1991年 | 370篇 |
1990年 | 317篇 |
1989年 | 295篇 |
1988年 | 240篇 |
1987年 | 244篇 |
1986年 | 231篇 |
1985年 | 490篇 |
1984年 | 596篇 |
1983年 | 390篇 |
1982年 | 447篇 |
1981年 | 401篇 |
1980年 | 346篇 |
1979年 | 320篇 |
1978年 | 273篇 |
1977年 | 184篇 |
1976年 | 165篇 |
1975年 | 132篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
高浓度IL-5可以从T细胞杂交瘤培养的上清液中获得。本文介绍分泌IL-5的T细胞杂交瘤的培养及其上清液中分高纯化IL-5的方法,提纯了高浓度的IL-5。 相似文献
173.
In human cortex and hippocampus area, [3H]5-HT (5 nM) labels 5-HT1A, 5-HT1D and 5-HT1E sites. After masking 5-HT1A receptors by 0.1 μM 8-OH-DPAT, the binding displaced by 0.1 μM 5-CT presumably represented 5-HT1D sites and the remaining binding 5-HT1E sites. In frontal cortex, 5-HT1A receptors represented the main binding in layers II and VI and a lower fraction on other layers. 5-HT1D and 5-HT1E sites, were more homogeneously distributed in layers II to VI (21–34% of specific [3H]5-HT binding). 5-HT1E sites were of similar affinities (KD close to 6–8 nM) in the cortical layers II to VI. In CA1 field of hippocampus, (pyramidal layer, stratum radiatum, molecular layer), CA2 and dentate gyrus, 5-HT1A receptors represented the major fraction, 5-HT1D sites a significant fraction and 5-HT1E a minor fraction of the specific [3H]5-HT binding. In CA3–CA4 fields, 5-HT1A receptors were less densely present, 5-HT1D sites were predominant and 5-HT1E sites represented a significant fraction (27%). The highest densities of 5-HT1E sites have been measured in subiculum, where 5-HT1A, 5-HT1D, and 5-HT1E binding sites were equally represented and in entorhinal cortex where 5-HT1E sites represented the major binding in layer III. They were also present in layers II and IV (29 and 24%) and, to a lesser extent, in layers V and VI. 5-HT1A sites were predominant in layer VI, II and V and were less abundant in other layers. 5-HT1D were homogeneously present in layers II, III, IV and were present in low amounts in other layers. No 5-HT1E were detected in choroid plexus, where [3H]5-HT was dramatically reduced by mesulergine (5-HT2C receptors). No significant displacement of [3H]5-HT by mesulergine was measured in other structures. 相似文献
174.
本文应用高效液相色谱与荧光分光光度计联机法检测55例胃液内5-羟色胺的含量,共分为正常、溃疡病、萎缩性胃炎、胃癌等4个组。其结果正常组含量为48.70±49.3ng/ml,溃疡病组含量为76.26±127.06ng/ml,慢性萎缩性胃炎组含量为197.29±128.4ng/ml,胃癌组含量为191.80±124.2ng/ml。4组之间进行对比分析,正常组和溃疡病组之间差异不明显(P>0.05),而萎缩性胃炎和胃癌两组与前两组之间差异均显著(P<0.01),但萎缩性胃炎和胃癌之间未见差异(P>0.05)。这充分证明5-羟色胺(5-HT)在萎缩性胃炎和胃癌的胃液中含量是很高的。对于胃癌和慢性萎缩性胃炎的诊断及与其它慢性胃病的鉴别诊断中可能起到很重要的作用。 相似文献
175.
本文报道2,5-二硝基苯酚在0.5mol/L氢氧化钠介质中及在40℃恒温水浴中加热15min的条件下与维生素C作用生成红色还原产物,其最大吸收波长位于500nm。维生素C浓度介于0.03~0.1mg/ml之间服从比耳定律,其mol吸光系数为3.2×10~3L·mol~(-1)·cm~(-1),Sandell灵敏度为0.055μg/cm~2。红色还原产物的色泽可稳定24h。本法曾用于药物片剂中维生素C含量的测定获得满意结果。 相似文献
176.
Immunosuppression of immunoglobulin synthesis seen in patients with multiple myeloma is in part due to immunosuppressive CD5 positive B cells. In a 13 year longitudinal study of an IgA-deficient blood donor who developed multiple myeloma, the presence of immunosuppressive CD5 positive B cells and T cells preceded the diagnosis of overt multiple myeloma and the appearance of immunosuppressive monocytes. These data argue that certain immune defects may be involved in the development of myeloma and are not simply a consequence of overt malignancy. 相似文献
177.
Triploid origin of the gibel carp as revealed by 5S rDNA localization and chromosome painting 总被引:2,自引:0,他引:2
5S ribosomal DNA (rDNA) was isolated and sequenced from the gibel carp Carassius auratus gibelio with 162 chromosomes and crucian carp Carassius auratus with 100 chromosomes, and fluorescent probes for chromosome localization were prepared to ascertain the ploidy origin and
evolutionary relationship between the two species. Using fluorescence in-situ hybridization (FISH), major 5S rDNA signals were localized to the short arms of three subtelocentric chromosomes in the gibel
carp and to the short arms of two subtelocentrics in the crucian carp. In addition, some minor signals were detected on other
chromosomes of both species. Simultaneously, six chromosomes were microdissected from the gibel carp metaphase spreads using
glass needles, and the isolated chromosomes were amplified in vitro by degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR). Significantly, when the DOP-PCR-generated probes
prepared from each single chromosome were hybridized, three same-sized chromosomes were painted in each gibel carp metaphase,
whereas only two painted chromosomes were observed in each crucian carp metaphase spread. The data indicate that gibel carp
is of triploid origin in comparison with diploid crucian carp. 相似文献
178.
179.
Yasukazu Kuroda Masahiko Mikuni Tetsuo Ogawa Kiyohisa Takahashi 《Psychopharmacology》1992,108(1-2):27-32
The effect of ACTH and/or adrenalectomy on serotonin (5-HT)2 receptor binding sites was evaluated in the neocortex of rat forebrain. One day after the adrenalectomy or sham operation, ACTH (50 µg/day) was injected subcutaneously into adult male SD rats for 10 consecutive days. Saturation analysis showed that subchronic ACTH treatment significantly increased the Bmax values for3H-ketanserin binding without any change in the Kd values. Moreover, this ACTH-induced increase in the Bmax values was prevented by adrenalectomy. The concentrations of 5-HT and 5-hydroxyindole acetic acid (5-HIAA) measured by HPLC-ECD were not altered by these manipulations. Ten-day administration of corticosterone (20 and 50 mg/kg) also increased 5-HT2 receptor density in the neocortex of rat forebrain. 5-HT2 (and 5-HT1C) receptor agonist, (±)DOI-induced wet-dog shakes in ACTH and/or adrenalectomy-treated rats were also examined. Ten-day administration of ACTH enhanced (±)DOI-induced wet-dog shakes and this increase was prevented by adrenalectomy. These results indicate that subchronic adrenocorticotropinadrenal axis activation of rats increases both the number of 5-HT2 receptors in neocortex of forebrain and the wet-dog shake responses induced by (±)DOI. 相似文献
180.
The effects of withdrawal from continuous administration of cocaine on behavioral sensitivity to apomorphine and monoamine receptor density were examined in rats. Subdermal minipumps that delivered either saline or 20 mg/kg/day cocaine hydrochloride were implanted for 2 weeks. Apomorphine-induced stereotypy (0.5 mg/kg, SC) was examined in separate groups of rats either 4 hr or 7, 28, or 60 days after removal of the minipumps. Transient enhanced sensitivity to apomorphine-induced stereotypy occurred during the course of withdrawal. Animals withdrawn from cocaine for 4 hours did not differ from controls in their sensitivity to apomorphine, whereas animals withdrawn from cocaine for 7 days exhibited an increase in apomorphine-induced oral stereotypy relative to controls. However, the enhanced stereotypy response was no longer evident in animals withdrawn for 28–60 days. The animals were sacrificed after behavioral testing, and their brains were assayed for changes in monoamine receptor density in the frontal cortex, caudate-putamen, and nucleus accumbens. The density of 3H-SCH-23390-labeled D1 receptors was altered in all three regions examined in a time-dependent manner that paralleled the changes in behavioral sensitivity to apomorphine. There was a transient decrease in D1 receptor density that was evident by 7 days following withdrawal from continuous cocaine administration and was no longer evident 28 or 60 days posttreatment. There were no changes in 3H-spiroperidol-labeled D2 receptors, 125-pindolol-labeled β-adrenergic receptors, or 3H-ketanserin-labeled 5-HT2 receptors in any of the regions examined at both 4 hr and 7 days after termination of the cocaine infusion. These findings are discussed in terms of their relevance to developing pharmacologic treatments for withdrawal from cocaine. © 1994 Wiley-Liss, Inc. 相似文献