全文获取类型
收费全文 | 3054篇 |
免费 | 247篇 |
国内免费 | 115篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 109篇 |
妇产科学 | 41篇 |
基础医学 | 402篇 |
口腔科学 | 47篇 |
临床医学 | 357篇 |
内科学 | 758篇 |
皮肤病学 | 65篇 |
神经病学 | 167篇 |
特种医学 | 405篇 |
外国民族医学 | 1篇 |
外科学 | 291篇 |
综合类 | 75篇 |
预防医学 | 248篇 |
眼科学 | 28篇 |
药学 | 245篇 |
中国医学 | 2篇 |
肿瘤学 | 153篇 |
出版年
2023年 | 16篇 |
2021年 | 47篇 |
2020年 | 30篇 |
2019年 | 35篇 |
2018年 | 52篇 |
2017年 | 39篇 |
2016年 | 39篇 |
2015年 | 53篇 |
2014年 | 69篇 |
2013年 | 107篇 |
2012年 | 93篇 |
2011年 | 126篇 |
2010年 | 86篇 |
2009年 | 101篇 |
2008年 | 108篇 |
2007年 | 162篇 |
2006年 | 109篇 |
2005年 | 124篇 |
2004年 | 101篇 |
2003年 | 75篇 |
2002年 | 80篇 |
2001年 | 50篇 |
2000年 | 77篇 |
1999年 | 66篇 |
1998年 | 106篇 |
1997年 | 122篇 |
1996年 | 124篇 |
1995年 | 85篇 |
1994年 | 76篇 |
1993年 | 85篇 |
1992年 | 54篇 |
1991年 | 56篇 |
1990年 | 54篇 |
1989年 | 75篇 |
1988年 | 63篇 |
1987年 | 75篇 |
1986年 | 57篇 |
1985年 | 68篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 31篇 |
1981年 | 31篇 |
1980年 | 42篇 |
1979年 | 21篇 |
1978年 | 23篇 |
1977年 | 27篇 |
1976年 | 43篇 |
1975年 | 25篇 |
1974年 | 17篇 |
1973年 | 16篇 |
排序方式: 共有3416条查询结果,搜索用时 1 毫秒
1.
Nonocclusive mesenteric ischemia (NOMI) is a disorder with an extremely high mortality. Salvage of affected patients requires early recognition and aggressive intervention to prevent intestinal gangrene. Dialysis patients represent a group at particularly high risk for this condition. Clinicians should develop a high index of suspicion for NOMI in dialysis patients to lessen the risk of death. A high interventional posture must be maintained due to the notoriously unreliable signs and symptoms of this disorder. 相似文献
2.
Summary— To investigate if the functional alterations observed in resistance arteries of spontaneously hypertensive rats (SHRs) were also present at the coronary level, in vitro experiments were performed in mesenteric resistance arteries (MRA) and in right (RIC) and left interventricular coronary (LIC) arteries taken from 15–25-week-old SHR and age-matched Wistar Kyoto rats WKYs. Using a passive extension protocol, internal diameters corresponding to 100 mmHg intraluminal pressure (D100) were determined and vessels were set up to a normalized internal diameter (0.9 D100). SHR mesenteric resistance arteries had a significantly smaller diameter compared to WKY arteries, whereas both types of SHR coronary arteries had a greater diameter compared to those of WKY rats. In arteries in the absence of contracting agonist, nitro-L-arginine (NOLA, 100 μM) induced a progressive rise in basal tone, which could be reversed by subsequent addition of L-arginine (100 μM) but not D-arginine (100 μM). When expressed as percent of maximal contractions induced by agonists (noradrenaline, NA [10 μM] in MRA; serotonin, 5-HT [10 μM], in RIC and LIC), these contractions were significantly stronger in WKY compared to SHR coronary and mesenteric resistance arteries. In NA-precontracted MRA and 5HT-precontracted coronary arteries in the presence of indomethacin (10 μM), the magnitude of acetylcholine-induced maximal relaxations (expressed as percent of maximal contractions induced by agonists) was greater in WKY compared to SHR arteries. After a 30-min incubation period, NOLA (100 μM) completely inhibited relaxations induced by acetylcholine (0.01–10 μM) in all types of precontracted arteries. Subsequent additions of sodium nitroprusside, (SNP, 10 μM) induced complete relaxations in all preparations. These results show that a basal release of NO or NO-like compound by endothelial cells is present in isolated mesenteric resistance and coronary arteries of WKY rats and SHRs. The contribution of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) to arterial tone was lower in MRA compared to coronary arteries in both strains and in SHR compared to WKY arteries. In the SHR preparations, the impaired relaxation induced by acetylcholine appeared to be due to a functional alteration of the endothelium in the presence of normal reactivity of the smooth muscle cells. 相似文献
3.
表小檗碱对α受体的作用 总被引:2,自引:0,他引:2
表小檗碱(epiberberine,EB)是从湖北产黄连(Coptis chinensis Franch)中提取的一种生物碱,属苯喹嗪类原小檗碱,对其药理作用的研究资料甚少,未见其对α肾上腺素体作用的报道。资料表明,许多原小檗碱类化合物有α受体阻滞作用,为从该类化合物中选择 相似文献
4.
5.
6.
Comparative testicular toxicity of bis(2-methoxyethyl) ether and 2-methoxyethanol in rats 总被引:2,自引:0,他引:2
Male rats were exposed to 0, 110, 370, or 1100 ppm bis(2-methoxyethyl)ether (diglyme) 6 h/day, 5 days/week for 2 weeks. One group of male rats was exposed to 300 ppm 2-methoxyethanol (2-ME) for 2 weeks as a positive control. Exposed rats were killed after 10 days of exposure and 14, 42, or 84 days post-exposure (PE), respectively. At 110 ppm diglyme, spermatocytes in pachytene and meiotic division at spermatogenic stages XII-XIV were mainly affected. At 370 ppm diglyme, affected germ cells were similar to those seen at 110 ppm diglyme, but round spermatids at spermatogenic stages I-VII were also affected. The testes regained normal spermatogenesis by 84 days PE. At 1100 ppm diglyme or 300 ppm 2-ME, marked testicular atrophy was found affecting all spermatogenic stages. Damaged seminiferous tubules were lined with regenerating pachytene spermatocytes at 14 days PE and with spermatocytes and round spermatids after 42 days PE. Most but not all testes in rats exposed to 300 ppm 2-ME or 1100 ppm diglyme had normal morphology after 84 days PE. Based on the observation of germ cell damage, spermatozoa population in the epidymal tubules, reversibility of spermatogenesis after various PE periods, testicular toxicity induced by 300 ppm 2-ME was more severe than that seen at 370 ppm diglyme but was slightly less remarkable than that of 1100 ppm diglyme. 相似文献
7.
Clare Bradley Rosalind Plowright John Stewart John Valentine Elke Witthaus 《Health and quality of life outcomes》2007,5(1):57
Background
The results of using status measures to identify any changes in treatment satisfaction strongly suggest a need for specific change instruments designed to overcome the ceiling effects frequently observed at baseline. Status measures may leave little room to show improvement in situations where baseline ceiling effects are observed. A change version of the DTSQ (DTSQc) is compared here with the original status (now called DTSQs) version to test the instruments' comparative ability to demonstrate change. 相似文献8.
Pernes JM; Vitoux JF; Brenoit P; Raynaud A; Parola JL; Roth JP; Angel CY; Fiessinger JN; Roncato M; Gaux JC 《Radiology》1986,158(2):481-485
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs. 相似文献
9.
D A Frambach C E Roy J L Valentine S F Boles J J Weiter C L Schepens 《Ophthalmic surgery》1988,19(2):98-100
The prevalence of cardiovascular disease (by EKG criteria) in patients with rhegmatogenous retinal detachments has been reported to be more than four times that found in age-matched controls. Adhesion between the retinal pigment epithelium (RPE) and the photoreceptors is facilitated by RPE transport. Because RPE transport is driven by a Na-K ATPase, it has been suggested that the correlation of EKG abnormalities and retinal detachment may be due to clinical use of digoxin, a Na-K ATPase inhibitor frequently given to patients with cardiovascular disease. The prevalence of EKG abnormalities in 299 consecutive patients with primary retinal detachment is about the same as that reported previously. However, 92% of these patients with EKG abnormalities did not take digoxin. Therefore, clinical use of digoxin cannot account for the reported association of EKG abnormalities and rhegmatogenous retinal detachment. 相似文献
10.
Nemaline myopathy of cats 总被引:2,自引:0,他引:2
An apparently inherited myopathy, characterized by the presence of large numbers of nemaline rods in skeletal muscle fibers, was investigated in five cats. Onset of signs varied from 6 months to 1.5 years of age and consisted of reluctance to move, jerky gait and muscle twitching, hyporeflexia, and muscle wasting, which was most prominent in the proximal muscles of the forelimbs. All of the cats, three males and two females, were from the same dam. In addition to the presence of rods, the myopathy was characterized by marked fiber size variation, with atrophy of type 1 and type 2a muscle fibers. In addition, there was infolding of the sarcolemma and fiber splitting. Ultrastructurally, the rods closely resembled those described in human nemaline myopathy. 相似文献