全文获取类型
收费全文 | 2132篇 |
免费 | 145篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 158篇 |
妇产科学 | 22篇 |
基础医学 | 291篇 |
口腔科学 | 47篇 |
临床医学 | 214篇 |
内科学 | 447篇 |
皮肤病学 | 42篇 |
神经病学 | 81篇 |
特种医学 | 478篇 |
外科学 | 157篇 |
综合类 | 40篇 |
一般理论 | 1篇 |
预防医学 | 88篇 |
眼科学 | 15篇 |
药学 | 111篇 |
中国医学 | 3篇 |
肿瘤学 | 100篇 |
出版年
2022年 | 6篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 19篇 |
2018年 | 29篇 |
2017年 | 22篇 |
2016年 | 32篇 |
2015年 | 37篇 |
2014年 | 45篇 |
2013年 | 86篇 |
2012年 | 44篇 |
2011年 | 57篇 |
2010年 | 79篇 |
2009年 | 73篇 |
2008年 | 56篇 |
2007年 | 42篇 |
2006年 | 41篇 |
2005年 | 51篇 |
2004年 | 31篇 |
2003年 | 31篇 |
2002年 | 36篇 |
2001年 | 34篇 |
2000年 | 51篇 |
1999年 | 38篇 |
1998年 | 134篇 |
1997年 | 127篇 |
1996年 | 129篇 |
1995年 | 94篇 |
1994年 | 78篇 |
1993年 | 83篇 |
1992年 | 40篇 |
1991年 | 26篇 |
1990年 | 25篇 |
1989年 | 67篇 |
1988年 | 53篇 |
1987年 | 56篇 |
1986年 | 55篇 |
1985年 | 53篇 |
1984年 | 31篇 |
1983年 | 35篇 |
1982年 | 39篇 |
1981年 | 21篇 |
1980年 | 39篇 |
1979年 | 17篇 |
1978年 | 18篇 |
1977年 | 20篇 |
1976年 | 25篇 |
1975年 | 28篇 |
1971年 | 5篇 |
1968年 | 4篇 |
排序方式: 共有2299条查询结果,搜索用时 15 毫秒
1.
J Chhabra Y-Z Li H Alkhouri A E Blake Q Ge C L Armour J M Hughes 《The European respiratory journal》2007,29(5):861-870
Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma. 相似文献
2.
Epicardial distribution of ST segment and T wave changes produced by stimulation of intrathoracic ganglia or cardiopulmonary nerves in dogs 总被引:1,自引:0,他引:1
Sixty-three ventricular epicardial electrograms were recorded simultaneously in 8 atropinized dogs during stimulation of acutely decentralized intrathoracic autonomic ganglia or cardiopulmonary nerves. Three variables were measured: (1) isochronal maps representing the epicardial activation sequence, (2) maps depicting changes in areas under the QRS complex and T wave (regional inhomogeneity of repolarization), and (3) local and total QT intervals. Neural stimulations did not alter the activation sequence but induced changes in the magnitude and polarity of the ST segments and T waves as well as in QRST areas. Stimulation of the same neural structure in different dogs induced electrical changes with different amplitudes and in different regions of the ventricles, except for the ventral lateral cardiopulmonary nerve which usually affected the dorsal wall of the left ventricle. Greatest changes occurred when the right recurrent, left intermediate medial, left caudal pole, left ventral lateral cardiopulmonary nerves and stellate ganglia were stimulated. Local QT durations either decreased or did not change, whereas total QT duration as measured using a root-mean-square signal did not change, indicating the regional nature of repolarization changes. Taken together, these data indicate that intrathoracic efferent sympathetic neurons can induce regional inhomogeneity of repolarization without prolonging the total QT interval. 相似文献
3.
We studied in anesthetized dogs, the effects of cardiopulmonary bypass with normothermic whole blood, crossclamping of the aortic root, and continuous warm blood cardioplegia on the ability of the efferent sympathetic nervous system to augment the heart and that of the efferent parasympathetic nervous system to depress the heart. In control states, heart rate, atrial force of contraction, and right and left ventricular wall systolic pressures were augmented by stimulation of the intrathoracic efferent sympathetic nervous system and by administration of isoproterenol into the systemic circulation. After 1 hour of normothermic cardiopulmonary bypass that utilized aortic crossclamping and continuous perfusion of the coronary arteries with normothermic blood (20 mEq/L potassium), cardiac-augmenting effects induced by the efferent sympathetic nervous system and by isoproterenol were similar. Depressive responses elicited by the efferent parasympathetic nervous system were also unaffected by these procedures. Continuous warm blood cardioplegia does not result in impairment of the efferent sympathetic nervous system regulating the heart. 相似文献
4.
Twenty-two adult patients with uncontrolled epilepsy and severe learning difficulties were included in an open study of vigabatrin. Patients were all in residential care and had experienced at least 12 seizures during the previous 12 months despite all attempts to optimize antiepileptic drug (AED) treatment. Following a 4 month baseline period, vigabatrin 500 mg twice daily was added to the current AED treatment and the dose increased according to response, up to a maximum of 4 g/day. Ten patients achieved a reduction in seizure frequency of more than 50% during this 4 month dose titration phase. Two patients had no seizures during the baseline period. For the 30 patients with seizures during the baseline period the median improvement in seizure frequency with the addition of vigabatrin was 49% (P = 0.014). The response rate was higher for patients with partial seizures than for those with generalized seizures. Ten patients continued with vigabatrin while the dose of one of their other AEDs was gradually reduced and successfully withdrawn in three patients. Adverse events were reported in 20 patients during the 64 week study period. The most frequently reported events were sedation (8 patients), aggression (4 patients), agitation (3 patients) and ataxia (3 patients). No patients were withdrawn from the study as a consequence of adverse events. Vigabatrin was therefore an effective add-on therapy in 45% of these difficult-to-treat patients and allowed reduction of other AED treatment in a small number. 相似文献
5.
Judith L. Black Peter R. A. Johnson Lorraine Alouan Carol L. Armour 《European journal of pharmacology》1990,180(2-3):311-317
This study investigated the effects of neurokinin A (NKA) on cholinergic neural responses in human bronchus. NKA (0.1 nM) did not alter the contractile response to submaximal electrical field stimulation. However, K+ channel blockade with 4-aminopyridine (4-AP) (0.1 mM) potentiated the response to electrical field stimulation (to 182 ± 25% of control, n = 4, P < 0.05) and subsequent addition of NKA in the presence of 4-AP produced further potentiation (to 123 ± 6% of the response to 4-AP n = 4, P < 0.05). Neither 4-AP (0.01 or 0.1 mM) nor NKA in the presence of 4-AP potentiated the actions of exogenous acetylcholine but in these experiments 4-AP itself produced a marked direct contractile response. Thus NKA in the presence of K+ channel blockade potentiates cholinergic neural response in human bronchus and this occurs at a prejunctional site. 相似文献
6.
S A Chalew R A Lozano K M Armour A A Kowarski 《International journal of obesity (2005)》1992,16(6):459-463
Obesity in childhood is characterized by subnormal integrated concentrations of growth hormone (IC-GH) and elevated integrated concentrations of insulin (IC-I). We tested whether a reduction of IC-I induced by a low calorie diet would lead to a rise of IC-GH into the normal range for age. Six obese children (body mass index (BMI) 39.1 +/- 9.2 kg/m2) underwent integrated concentration (IC) studies by continuous withdrawal before and again 5-8 weeks after being on a low calorie diet. In response to the diet BMI was lower 34.7 +/- 9.4 kg/m2 (P less than 0.003), and IC-I was considerably reduced, 479 +/- 255 pM initially vs. 109 +/- 109 pM on the diet, P less than 0.0008. IC-GH increased modestly from 1.6 +/- 0.6 micrograms/l initially to 2.4 +/- 0.6 micrograms/l, P less than 0.01 on the diet. None of the patients had repeat IC-GH levels which were above the lower limit of normal for lean children of normal stature (3.2 micrograms/l). Single sample insulin-like growth factor 1 (IGF-1) levels were unchanged: 40.9 +/- 23.1 nM initially vs. 49.7 +/- 25.7 nM (314.6 +/- 197.7 vs. 382.5 +/- 217.0 ng/ml, n.s.). Thus reduction of high insulin concentrations during 5-8 weeks of a low calorie diet has only a small effect on IC-GH in obese children. Factors other than circulating insulin levels are likely to play the major role in mediating the reduced levels of GH observed in obesity. 相似文献
7.
We report an adult female with a rare giant choledochal cyst. The patient presented following a normal pregnancy with the classical triad of an abdominal mass associated with jaundice and right upper quadrant abdominal pain. The cyst was excised using an intramural technique and biliary reconstruction achieved with a Roux-en-Y hepaticojejunostomy. Our patient has remained well with no evidence of malignancy over a 12 year review period. The aetiology and current management of this condition are discussed. 相似文献
8.
Na+ dependence of in vitro pancreatic amylase release 总被引:1,自引:0,他引:1
9.
Cellular dysfunction in the diabetic fibroblast: impairment in migration,vascular endothelial growth factor production,and response to hypoxia 总被引:15,自引:0,他引:15 下载免费PDF全文
Lerman OZ Galiano RD Armour M Levine JP Gurtner GC 《The American journal of pathology》2003,163(1):303-312
Although it is known that systemic diseases such as diabetes result in impaired wound healing, the mechanism for this impairment is not understood. Because fibroblasts are essential for wound repair, we compared the in vitro behavior of fibroblasts cultured from diabetic, leptin receptor-deficient (db/db) mice with wild-type fibroblasts from mice of the same genetic background in processes important during tissue repair. Adult diabetic mouse fibroblast migration exhibited a 75% reduction in migration compared to normal fibroblasts (P < 0.001) and was not significantly stimulated by hypoxia (1% O(2)), whereas wild-type fibroblast migration was up-regulated nearly twofold in hypoxic conditions (P < 0.05). Diabetic fibroblasts produced twice the amount of pro-matrix metalloproteinase-9 as normal fibroblasts, as measured by both gelatin zymography and enzyme-linked immunosorbent assay (P < 0.05). Adult diabetic fibroblasts exhibited a sevenfold impairment in vascular endothelial growth factor (VEGF) production (4.5 +/- 1.3 pg/ml versus 34.8 +/- 3.3 pg/ml, P < 0.001) compared to wild-type fibroblasts. Moreover, wild-type fibroblast production of VEGF increased threefold in response to hypoxia, whereas diabetic fibroblast production of VEGF was not up-regulated in hypoxic conditions (P < 0.001). To address the question whether these differences resulted from chronic hyperglycemia or absence of the leptin receptor, fibroblasts were harvested from newborn db/db mice before the onset of diabetes (4 to 5 weeks old). These fibroblasts showed no impairments in VEGF production under basal or hypoxic conditions, confirming that the results from db/db fibroblasts in mature mice resulted from the diabetic state and were not because of alterations in the leptin-leptin receptor axis. Markers of cellular viability including proliferation and senescence were not significantly different between diabetic and wild-type fibroblasts. We conclude that, in vitro, diabetic fibroblasts show selective impairments in discrete cellular processes critical for tissue repair including cellular migration, VEGF production, and the response to hypoxia. The VEGF abnormalities developed concurrently with the onset of hyperglycemia and were not seen in normoglycemic, leptin receptor-deficient db/db mice. These observations support a role for fibroblast dysfunction in the impaired wound healing observed in human diabetics, and also suggest a mechanism for the poor clinical outcomes that occur after ischemic injury in diabetic patients. 相似文献
10.