全文获取类型
收费全文 | 11062篇 |
免费 | 580篇 |
国内免费 | 490篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 420篇 |
妇产科学 | 131篇 |
基础医学 | 1103篇 |
口腔科学 | 92篇 |
临床医学 | 717篇 |
内科学 | 1893篇 |
皮肤病学 | 111篇 |
神经病学 | 843篇 |
特种医学 | 189篇 |
外科学 | 470篇 |
综合类 | 975篇 |
现状与发展 | 4篇 |
预防医学 | 1908篇 |
眼科学 | 81篇 |
药学 | 2087篇 |
中国医学 | 843篇 |
肿瘤学 | 250篇 |
出版年
2023年 | 141篇 |
2022年 | 259篇 |
2021年 | 497篇 |
2020年 | 356篇 |
2019年 | 313篇 |
2018年 | 279篇 |
2017年 | 308篇 |
2016年 | 342篇 |
2015年 | 332篇 |
2014年 | 557篇 |
2013年 | 902篇 |
2012年 | 436篇 |
2011年 | 551篇 |
2010年 | 412篇 |
2009年 | 382篇 |
2008年 | 424篇 |
2007年 | 393篇 |
2006年 | 356篇 |
2005年 | 366篇 |
2004年 | 323篇 |
2003年 | 284篇 |
2002年 | 260篇 |
2001年 | 224篇 |
2000年 | 226篇 |
1999年 | 195篇 |
1998年 | 196篇 |
1997年 | 178篇 |
1996年 | 161篇 |
1995年 | 145篇 |
1994年 | 157篇 |
1993年 | 149篇 |
1992年 | 133篇 |
1991年 | 122篇 |
1990年 | 139篇 |
1989年 | 148篇 |
1988年 | 130篇 |
1987年 | 114篇 |
1986年 | 98篇 |
1985年 | 132篇 |
1984年 | 136篇 |
1983年 | 96篇 |
1982年 | 126篇 |
1981年 | 92篇 |
1980年 | 94篇 |
1979年 | 81篇 |
1978年 | 74篇 |
1977年 | 62篇 |
1976年 | 61篇 |
1974年 | 35篇 |
1973年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
31.
32.
ARDS时IL-6和IL-8的动态变化和作用 总被引:1,自引:1,他引:0
目的:探讨肠源性内毒素对血浆 IL- 6和 IL- 8水平的影响以及在油酸所致 ARDS过程中的作用。 方法 :静脉注射油酸造成 ARDS,观察门静脉和腔静脉血内毒素及 IL- 6与 IL- 8水平的动态变化。结果:油酸注入 6 0min后门静脉和腔静脉血浆内毒素及 IL- 6和 IL- 8水平开始升高 ,并随着时间的延长而显著升高 ,各时间点与对照组相比均有显著性差异 ,同时门静脉血浆水平高于腔静脉血浆水平 (P <0 .0 5~ 0 .0 1) ;而且油酸注入 90 min和12 0 min后的水平又比 6 0 min时均有增加 (P <0 .0 1) ;内毒素水平的变化与 IL- 6和 IL- 8水平变化呈正相关关系(P <0 .0 1) 。结论 :在油酸所致 ARDS过程中有肠源性内毒素血症的发生 ,肠源性内毒素可诱导 IL- 6和 IL- 8的产生 ,参与油酸致急性肺损伤的发展和由此导致的多器官功能障碍的发生 相似文献
33.
Taurine has been proposed as an inhibitory neurotransmitter or neuromodulator in the vertebrate central nervous system. Within the spinal cord, taurine has been shown to have a direct inhibitory effect on spinal neurons and to have a selective antinociceptive effect on chemically induced nociception. Although sufficient data exists to suggest that taurine plays a neurotransmitter or neuromodulatory role in the spinal cord, it is not known whether this amino acid is present in axon terminals nor if this amino acid has a unique pattern of distribution within spinal tissue. To address these questions a monoclonal antibody against taurine was employed to localize taurine-like immunoreactivity in the dorsal horn of the rat spinal cord by using both light and electron microscopic techniques. Taurine-like immunoreactivity was most dense and most prominent in laminae I and II of the dorsal horn. A moderate amount of immunoreactivity was also present in laminae VIII and IX and X while the remaining laminae were only lightly stained. In laminae I and II taurine-like immunostaining was evident within neuronal cell bodies, dendrites, myelinated and unmyelinated axons, axon terminals, and astrocytes and their processes. Cell counts of these two laminae indicated that approximately 30% of neuronal perikarya at the C2 level, 52% of neuronal perikarya at the T6 level, and 18% of neuronal perikarya at the L2 level of the cord exhibited taurine-like immunoreactivity. With preembedding diaminobenzidine staining, approximately 20% of the axons examined in laminae I and II were found to be immunoreactive for taurine. Using postembedding immunogold staining in combination with quantitative procedures, the highest densities of gold particles were found in axon terminals containing pleomorphic vesicles and forming symmetrical synapses (36.8 particles/micron2), in a subpopulation of myelinated axons (34.2 particles/micron2), in a subpopulation of neuronal dendrites (32.6 particles/micron2), and in capillary endothelial cells (39.8 particles/micron2). Moderate labeling occurred in astrocytes (20.9 particles/micron2) and neuronal perikarya (18.7 particles/micron2). The localization of taurine to presumptive inhibitory axon terminals provides anatomical support for the hypothesis that taurine may serve an inhibitory neurotransmitter role in the superficial dorsal horn of the spinal cord. On the other hand, its localization to astrocytes and endothelial cells within both the dorsal ventral horns implies that it serves other nonneuronal functions as well. 相似文献
34.
根据胜利黄岛原油的性质,在筛选了几十种破乳剂的基础上,选择了酚醛树脂和环氧环烷,环氧乙烷的嵌段共聚物作破乳剂,探讨了破乳剂组成对原油脱水,脱盐以及界面张力的影响,通过静态脱盐,脱水试验,得到了适合黄岛原油的最佳破乳剂组成。 相似文献
35.
目的:观察多囊卵巢综合征(PCOS)患者血清游离脂肪酸(FFAs)水平变化及相关因素分析.方法:PCOS患者(39例)分为肥胖组(11例)和非肥胖组(28例),对照组为年龄匹配的健康妇女(21例).测定血清FFAs、游离睾酮、雄烯二酮、睾酮、性激素结合球蛋白、TC、TG、HDL-c、LDL-c、空腹血糖(FPG)、餐后2h血糖(PPG)、空腹胰岛素及胰岛素敏感性(M值,两步法高胰岛素-正葡萄糖钳夹技术评价).结果:血清FFAs水平在肥胖PCOS组和非肥胖PCOS组之间无明显差别,但均高于对照组(P<0.05).对所有研究对象的血清FFAs进行相关分析表明FFAs分别与游离睾酮(r=0.464,P=0.001),睾酮(r=0.368,P=0.01),雄烯二酮(r=0.418,P=0.003)和PPG(r=0.334,P=0.014)呈正相关,与M值(r=-0.392,P=0.003)呈负相关.进一步做回归分析表明,FFAs与游离睾酮显著相关(β=0.219,P<0.05).结论:与年龄相当的健康妇女比较,PCOS妇女血清FFAs水平显著增高,并且FFAs升高与游离睾酮水平升高有关. 相似文献
36.
I. Sioen † C. Matthys G. De Backer J. Van Camp† & S. De Henauw 《Journal of human nutrition and dietetics》2007,20(6):580-589
BACKGROUND: Regular seafood consumption is recommended in dietary guidelines. The aim of this study was to investigate the importance of seafood as a nutrient source in adolescents' diet and the extent to which seafood consumption can increase the intake of omega-3 polyunsaturated fatty acids and vitamin D. METHODS: Consumption data recorded during seven consecutive days for 341 adolescents selected in Ghent (Belgium) were used to estimate the intake of vitamin D, linoleic (LA), alpha-linolenic (LNA), arachidonic (AA), eicosapentaenoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acid. RESULTS: The adolescents consumed on average 3.21 microg/day vitamin D, 11.7 g/day LA and 1.4 g/day LNA. The mean intakes of AA, EPA, DPA and DHA were 83.2, 55.9, 18.4 and 111.4 mg/day respectively. The major source of vitamin D was fortified margarine. Fats and oils were the main sources for LA and LNA. The intake of AA was mainly contributed by meat, poultry and eggs. Fish and seafood contributed for 84.1%, 59.3% and 64.4% respectively for EPA, DPA and DHA. CONCLUSION: Flemish adolescents would benefit from increased seafood consumption, as this would lead to a higher intake of EPA and DHA as well as of vitamin D. Moreover, replacement of foods rich in saturated fat (SFA) by seafood products can help to reduce SFA intake. 相似文献
37.
探讨了缺铁性贫血蛋白质营养状况的变化。对85名正常组,20名缺铁性贫血儿童血清前白蛋白及血浆中19种游离氨基酸水平玉测定。结果缺铁性贫血组儿童PAB明显下降,血浆氨基酸含量、必需氨基酸、支链氨基酸;必需/总氨基酸、支链/非支链氨基酸均明显低于正常儿童,提示缺铁性贫血儿童常同时伴有蛋白营养不良状况。 相似文献
38.
The effects of gonadal steroids on GABA-, taurine (TAU)- and N-methyl-D, L-aspartate (NMA)-induced gonadotropin-II (GTH-II) release were investigated in male and female goldfish in vivo. In sexually regressed goldfish (both sexes mixed), intraperitoneal implantation for 5 to 10 days with solid Silastic pellets containing testosterone (100 μg/g), oestradiol (100 μg/g) or progesterone (100 μg/g) was previously shown to elevate serum sex steroid levels to values comparable to those in sexually mature animals, and to potentiate gonadotropin-releasing hormone-stimulated GTH-II release. In the present study, testosterone but not oestradiol or progesterone enhanced the stimulatory effects of exogenous GABA (100 μg/g) on GTH-II release in vivo. TAU (1 mg/g) stimulated GTH-II release in sexually regressed mixed sex and sexually recrudescent male goldfish, and both testosterone and oestradiol implantation enhanced GTH-II release induced by TAU. The glutamate agonist NMA (25 to 50 μg/g) was also found to stimulate GTH-II release; however it was relatively less effective in elevating serum GTH-II levels than GABA and TAU, and its effects were not modulated by sex steroid treatments. Pretreatment of goldfish with α-methyl-p-tyrosine to deplete brain and pituitary catecholam-ines did not affect NMA action on GTH-II release. Our results indicate that GABA, TAU and NMA are involved in the neuroendocrine regulation of GTH-II release in goldfish, and support the idea that testosterone participates in the positive feedback regulation of pituitary gonadotropin release in a non-mammalian vertebrate by enhancing GABA- and TAU-stimulated GTH release in vivo. 相似文献
39.
目的 :观测心内直视手术中肌氨肽苷抗心肌缺血 /再灌注损伤的作用 ,评价其心肌保护效果。 方法 :34例体外循环下行瓣膜置换术患者随机分为对照组和治疗组 ,分别于手术前、主动脉阻断前、主动脉开放即刻及主动脉开放后 2、6、12、2 4、4 8、72、96h共 10个时点从中心静脉取血 ,测定心肌肌钙蛋白I(cTnI)、乳酸脱氢酶 (LDH)、磷酸肌酸激酶 (CK)和磷酸肌酸激酶同功酶 (CK MB)水平。 结果 :术前两组的cTnI、LDH、CK、CK MB水平均在正常范围内 ,开放主动脉后 2h开始升高 ,术后 12~ 2 4h达峰值 ,随后缓慢下降。对照组术后各时点cTnI、LDH、CK、CK MB水平明显升高 (P <0 .0 5~ 0 .0 1) ;治疗组cTnI水平较术前无明显升高 (P >0 .0 5 ) ,而LDH、CK、CK MB水平较术前明显升高 (P <0 .0 5 ) ,但升高的程度明显低于对照组 (P <0 .0 5~ 0 .0 1)。 结论 :肌氨肽苷用于冷心停搏液中 ,有良好的心肌保护作用 相似文献
40.
J. A. Dunstan J. Roper L. Mitoulas† P. E. Hartmann† K. Simmer S. L. Prescott 《Clinical and experimental allergy》2004,34(8):1237-1242
BACKGROUND: Breast milk contains many immunomodulatory factors (soluble CD14 (sCD14), IgA and cytokines) with the potential to influence infant immune development. OBJECTIVE: To determine if changes in breast milk omega-3 polyunsaturated fatty acid (n-3 PUFA) composition as a result of maternal dietary fish oil supplementation during pregnancy can modify levels of these immunological parameters in breast milk. METHOD: In a randomized controlled trial, 83 atopic women received either 4 g fish oil capsules (containing 3.7 g n-3 PUFA) (n = 40) or 4 g olive oil capsules (n = 43) from 20 weeks gestation until delivery. Breast milk was collected 3 days post-partum and fatty acids were analysed by gas liquid chromatography and IgA, sCD14 and cytokines (IL-5, IL-6, IL-10, TNF-alpha and IFN-gamma) were quantitated by ELISA or time resolved fluorescence (TRF). RESULTS: Omega-3 docosahexaenoic acid (DHA; 22:6n-3) and eicosapentaenoic acid (EPA; 20:5n-3) levels were significantly higher (P < 0.001) in breast milk from women supplemented with fish oil (n = 33, DHA mean 1.15%, SD 0.47% and EPA mean 0.16%, SD 0.07%) than in samples from the control group (n = 40, DHA mean 0.50%, SD 0.17% and EPA mean 0.05%, SD 0.02%). Breast milk arachidonic acid (AA; 20:4n-6) levels were significantly lower (P = 0.045) in the fish oil group (mean 0.55%, SD 0.12%) compared with the control group (mean 0.61%, SD 0.14%). Breast milk IgA was positively correlated with DHA (P = 0.046) and 22:5n-3 (P = 0.003), but inversely correlated with linoleic acid (LA; 18:2n-6) (P=0.034). Levels of sCD14 were also positively correlated with 22:5n-3 (P=0.009). Cytokines involved in IgA synthesis (IL-10 and IL-6) were also significantly correlated with both IgA and n-3 PUFA levels, although there were no differences in the levels of breast milk IgA, sCD14 or cytokines between study groups. CONCLUSION: Supplementation with fish oil during pregnancy significantly alters early post-partum breast milk fatty acid composition. omega-3 PUFA levels were positively associated with IgA and sCD14 levels, suggesting a relationship between fatty acid status and mucosal immune function. 相似文献