全文获取类型
收费全文 | 5465篇 |
免费 | 363篇 |
国内免费 | 127篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 204篇 |
妇产科学 | 78篇 |
基础医学 | 782篇 |
口腔科学 | 231篇 |
临床医学 | 533篇 |
内科学 | 1193篇 |
皮肤病学 | 146篇 |
神经病学 | 506篇 |
特种医学 | 432篇 |
外国民族医学 | 1篇 |
外科学 | 477篇 |
综合类 | 64篇 |
一般理论 | 1篇 |
预防医学 | 377篇 |
眼科学 | 51篇 |
药学 | 455篇 |
中国医学 | 2篇 |
肿瘤学 | 365篇 |
出版年
2021年 | 64篇 |
2020年 | 55篇 |
2019年 | 59篇 |
2018年 | 78篇 |
2017年 | 46篇 |
2016年 | 79篇 |
2015年 | 68篇 |
2014年 | 85篇 |
2013年 | 170篇 |
2012年 | 206篇 |
2011年 | 209篇 |
2010年 | 137篇 |
2009年 | 136篇 |
2008年 | 228篇 |
2007年 | 253篇 |
2006年 | 245篇 |
2005年 | 250篇 |
2004年 | 210篇 |
2003年 | 193篇 |
2002年 | 185篇 |
2001年 | 173篇 |
2000年 | 160篇 |
1999年 | 145篇 |
1998年 | 139篇 |
1997年 | 135篇 |
1996年 | 142篇 |
1995年 | 98篇 |
1994年 | 94篇 |
1993年 | 100篇 |
1992年 | 140篇 |
1991年 | 140篇 |
1990年 | 118篇 |
1989年 | 154篇 |
1988年 | 106篇 |
1987年 | 129篇 |
1986年 | 108篇 |
1985年 | 139篇 |
1984年 | 83篇 |
1983年 | 69篇 |
1982年 | 66篇 |
1981年 | 46篇 |
1980年 | 55篇 |
1979年 | 40篇 |
1978年 | 47篇 |
1977年 | 45篇 |
1976年 | 44篇 |
1975年 | 40篇 |
1974年 | 31篇 |
1973年 | 20篇 |
1972年 | 27篇 |
排序方式: 共有5955条查询结果,搜索用时 15 毫秒
1.
2.
3.
M Müller J Grunewald C Olgart H?glund B Dahlén A Eklund H Stridh 《The European respiratory journal》2006,28(3):513-522
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation. 相似文献
4.
Erika E Forbes Douglas E Williamson Neal D Ryan Boris Birmaher David A Axelson Ronald E Dahl 《Neuropsychopharmacology》2006,59(1):24-30
BACKGROUND: Changes in the hypothalamic-pituitary-adrenal (HPA) axis, as evidenced by patterns of cortisol secretion, have been of interest in understanding depression and anxiety disorders across the life span. Previous studies of pediatric depression have pointed to the period around sleep onset as a key time point for observing alterations in cortisol secretion associated with affective disorders. Evidence also indicates that pubertal development may influence the expression of HPA dysregulation. We hypothesized that adolescents with depression and youth with anxiety disorders exhibit elevated peri-sleep-onset cortisol. METHODS: Plasma cortisol was sampled every 20 min around sleep onset from children and adolescents with major depressive disorder (n = 116), anxiety disorders (n = 32), or no history of psychiatric disorder (control; n = 76). Sleep onset was determined by polysomnography. Classification of participants as children or adolescents was based on Tanner staging of pubertal maturation. RESULTS: Children with anxiety disorders had higher peri-sleep-onset cortisol than children with depression or control children. Adolescents with depression had marginally higher peri-sleep-onset cortisol than control adolescents and significantly higher peri-sleep-onset cortisol than children with depression. CONCLUSIONS: Depression and anxiety are associated with altered cortisol secretion around sleep onset, and these changes appear to be influenced by pubertal maturation. 相似文献
5.
6.
7.
Clonidine (10 micrograms X kg-1) reduced by almost 50% the increase in plasma neuropeptide (NPY)-like immunoreactivity (-LI) induced by preganglionic nerve stimulation at 8 Hz. This effect was reversed by yohimbine (1 mg X kg-1) which caused a three-fold increase of the plasma NPY-LI. Prazosin (1 mg X kg-1) had no such effect. Guanethidine (5 mg X kg-1) reduced the stimulation-evoked increase in plasma NPY-LI. It is concluded that the release of NPY-LI evoked by nerve stimulation from sympathetic nerve terminals is controlled by a presynaptic alpha 2-adrenoceptor-mediated mechanism. 相似文献
8.
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
9.
10.