全文获取类型
收费全文 | 1413篇 |
免费 | 51篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 23篇 |
妇产科学 | 18篇 |
基础医学 | 167篇 |
口腔科学 | 110篇 |
临床医学 | 255篇 |
内科学 | 173篇 |
皮肤病学 | 2篇 |
神经病学 | 198篇 |
特种医学 | 31篇 |
外科学 | 185篇 |
综合类 | 3篇 |
预防医学 | 90篇 |
眼科学 | 6篇 |
药学 | 134篇 |
肿瘤学 | 68篇 |
出版年
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 26篇 |
2016年 | 24篇 |
2015年 | 18篇 |
2014年 | 33篇 |
2013年 | 47篇 |
2012年 | 62篇 |
2011年 | 69篇 |
2010年 | 38篇 |
2009年 | 47篇 |
2008年 | 89篇 |
2007年 | 81篇 |
2006年 | 68篇 |
2005年 | 68篇 |
2004年 | 69篇 |
2003年 | 101篇 |
2002年 | 86篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 26篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 23篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1977年 | 7篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1974年 | 13篇 |
1971年 | 8篇 |
1968年 | 8篇 |
1967年 | 9篇 |
1966年 | 13篇 |
排序方式: 共有1464条查询结果,搜索用时 15 毫秒
11.
O Sjaastad 《Functional neurology》1986,1(4):467-471
Four headache patients, 3 females and 1 male, are described, who all have experienced episodes with complete transitory blindness; in 3 it was bilateral, in the 4th there was asymmetry, the vision nevertheless also being markedly reduced globally in the other eye. Two of the patients got the visual disturbance far ahead of the headache episodes. These may or may not coincide with the visual disturbance. After some time, the visual disturbances in 3 of the patients have changed character, in that a unilateral transitory blindness or homonymous fortification spectra have supervened. In the last one they stopped altogether 5-6 years ago. The relationship of such blindness to migraine ("retinal", "basilar", etc.), TIA and even possible epilepsy is intricate. These four patients may not even suffer from the same condition. 相似文献
12.
Borgen Nicolai Topstad Olweus Dan Kirkebøen Lars Johannessen Breivik Kyrre Solberg Mona Elin Frønes Ivar Cross Donna Raaum Oddbjørn 《Prevention science》2021,22(8):1147-1158
Prevention Science - The effectiveness of bullying prevention programs has led to expectations that these programs could have effects beyond their primary goals. By reducing the number of victims... 相似文献
13.
Summary Uridine 5-triphosphate- (UTP-) and adenosine 5-triphosphate-(ATP) induced vasoconstriction was studied in the rabbit basilar artery. The arteries were incubated and perfused at a constant rate of flow. Vasoconstriction was measured as an increase in perfusion pressure.Serotonin, histamine and noradrenaline caused concentration-dependent vasoconstriction, with potency decreasing in that order. Of the nucleotides tested, UTP, UDP, UMP, CTP, ATP, ADP, adenosine 5-O-(3-thio)triphosphate (ATPS), and ,-imido adenosine 5-triphosphate (AMP-PNP) elicited concentration-dependent vasoconstriction, whereas AMP, 2-methylthio-ATP, , -methylene-ATP and ,-methylene-ATP up to 10–3 mol/l caused no or only a very small increase in perfusion pressure. The order of potency of the pyrimidine nucleotides was: UTP = UDP UMP = CTP; that of the purine nucleotides was: ATPS > AMP-PNP > ATP > ADP > 2-methylthio-ATP = , -methylene-ATP = ,-methylene-ATP. The vasoconstrictor effects of UTP and ATP were not or only to a minor degree influenced by: phentolamine; a mixture of atropine, diphenhydramine and methysergide; indometacin; nordihydroguaiaretic acid; denervation by 6-hydroxydopamine; or mechanical removal of endothelium. Prolonged exposure to ,-methylene-ATP elicited only a very small vasoconstriction and did not change the constrictor effects of UTP or ATP. Prolonged exposure to ATPS elicited marked vasoconstriction; subsequently, responses to ATP were reduced whereas those to UTP were, if anything, slightly enhanced. Reactive blue 2 reduced neither the UTP- nor the ATP-induced vasoconstriction. ATP 10–3 mol/l elicited marked additional vasoconstriction after precontraction with UTP 10–3 mol/l, whereas UTP elicited only a very small additional vasoconstriction when its concentration was doubled from 10–3 to 2 × 10–3 mol/l.It is concluded that, in the rabbit basilar artery, the vasoconstrictor response to UTP is mediated by a pyrimidine nucleotide receptor which is distinct from the P2-purinoceptor, and that the vasoconstrictor response to ATP is mediated by a P2-receptor which is distinct from the known P2-subtypes.Send offprint requests to I. v. Kügelgen at the above address 相似文献
14.
Clemens Allgaier Henning Wellmann Angelika Schobert Gerhart Kurz Ivar von Kügelgen 《Naunyn-Schmiedeberg's archives of pharmacology》1995,352(1):25-30
The ATP-induced increase in tritium outflow from cultured chick sympathetic neurons prelabelled with [3H]-noradrenaline was investigated.Seven days-old dissociated cell cultures of embryonic paravertebral ganglia, loaded with [3H]-noradrenaline (0.05 M), were superfused in the presence of (+)-oxaprotiline and exposed to ATP, ATP-analogues, or 1,1-dimethyl-4-piperazinium (DMPP) for 2 min. ATP (3 LM-3 mM), 2-methylthio-ATP (3–100 M), as well as DMPP (10 and 100 M) induced a significant overflow of tritium. The EC50-value of ATP was 20 M. Both the ATP-induced and the DMPP-induced tritium overflow was Ca2+-dependent and sensitive to tetrodotoxin (0.3 M) and -conotoxin (0.1 M); in addition, it was inhibited by the 2-adrenoceptor agonist 5-bromo-6-(2-imidazoline-2-ylamino)-quinoxaline (UK-14,304; 1 M). The effects of ATP and DMPP were not additive. The ATP-induced as well as the DMPP-induced overflow of tritium was diminished by the P2-purinoceptor antagonists suramin (300 M) and reactive blue 2 (3 M); in all 4 cases, the inhibition amouted to approximately 40%. The tritium overflow induced by ATP or DMPP was almost abolished by the nicotinic receptor antagonist mecamylamine (10 M) and markedly inhibited by hexamethonium (100 M). Neither ATP nor electrical stimulation caused an overflow of tritium from cultures loaded with [3H]-choline.The results suggest that ATP at molar concentrations induces noradrenaline release from cultured chick sympathetic neurons via an action on a subclass of the nicotinic cholinoceptor. 相似文献
15.
Piotr Kruszewski Maria Luisa Fasano AIf O. Brubakk Jie Ming Shen Trond Sand Ottar Sjaastad 《Headache》1991,31(6):399-405
The recently described "Sunct" syndrome is a rare picture of unilateral, shortlasting headache attacks accompanied by autonomic phenomena (conjunctival injection, tearing, etc.) on the symptomatic side. Heart rate and blood pressure were monitored in two elderly "Sunct" patients during and outside headache attacks. An ultrasound Doppler servo method was used for the non-invasive, continuous, beat-to-beat determination of instantaneous arterial blood pressure. In a third patient, systolic and diastolic blood pressure, both outside and during pain paroxysms, were assessed using the standard Korotkoff method. Heart rate was found to be significantly decreased during pain paroxysms. Systolic blood pressure was observed to be significantly increased during attacks, when compared with the inter-attack period, while a less consistent pattern was observed for diastolic blood pressure. Some of the changes in the cardiovascular system seemed to start prior to pain onset. Therefore, it seems unlikely that these changes were caused by pain activation of the sympathetic nervous system or the oculocardiac reflex. 相似文献
16.
Cluster headache syndrome and migrain. Ophthalmological support for a two-entity theory 总被引:1,自引:0,他引:1
Patients suffering from migraine, cluster headache and atypical cluster headache, including patients with chronic paroxysmal hemicrania, were studied with respect to corneal temperature, intraocular pressure and corneal indentation pulse amplitude changes during pain attacks. Significant rises in these three parameters were deomonstrated during attacks of cluster headache and atypical cluster headache, indicating that intraocular vasodilation with increased ocular blood flow occurs during attacks. No definite changes were found in migraine. The results strongly suggest that significant pathophysiological differences exist between migraine and cluster headache. The point is stressed that these disorders probably represent separate pathogenetic entities and should be classified as such, and not be grouped together within an ill-defined group of "vascular headache". 相似文献
17.
Dietary polyamines promote the growth of azoxymethane-induced aberrant crypt foci in rat colon 总被引:1,自引:1,他引:1
We have examined whether dietary polyamines influence the formation and
initial growth of azoxymethane (AOM)-induced aberrant crypt foci (ACF) in
rat colon. Effects of a combination of dietary polyamines at three dose
levels (putrescine: 50, 280, 740 nmol/g; spermidine: 10, 261, 763 nmol/g;
spermine: 1, 31, 91 nmol/g) in the polyamine-poor AIN-76A diet were studied
in animals in two different experimental situations: animals treated with
AOM alone and animals treated with AOM + difluoromethylornithine (DFMO), a
specific inhibitor of endogenous polyamine synthesis. In both experimental
situations, dietary polyamines enhanced the growth of ACF, expressed as the
number of large ACF (foci with three or more aberrant crypts, ACF > or =
3), whereas the formation of ACF, expressed as the number of ACF, was
apparently not altered. In animals treated with AOM alone, maximal growth
enhancing effect on ACF was nearly obtained with the median level of
dietary polyamine. In rats fed a low polyamine diet, basic AIN-76A, DFMO
reduced the growth of AOM-induced ACF by 83%. This inhibitory effect of
DFMO was counteracted by dietary polyamines in a dose- dependent manner,
and it was abolished at the highest level of polyamines. In conclusion, it
was demonstrated that dietary polyamines are able to enhance the growth of
AOM-induced ACF. Further, dietary polyamines reversed the DFMO-caused
inhibition of ACF growth, probably by compensating for the DFMO-reduced
endogenous polyamine synthesis.
相似文献
18.
78 rats weighing 180–200 g were used to assess the bone tissue responses to three periodontal dressings (Coe-pak, Peripac and Ward's Wondrpak). The dressings were implanted subscutaneously on periosteal covered and denuded bone. Sham operated animals served as controls and a comparison btween the responses produced by the three dressngs were made.
In one series the dressings remained in situ for 3, 7, 14, 30 and 90 days. Osteocyte damage of varying extent was recorded for all materials. Remodelling of the bone surface adjacent to the dressing was observed. Bone resorption was never foud in the gournd defect produced to denude the bone tissue, but repair of the defect by bone formation was observed after long observation periods. This repair was retarded in some animals were Ward's Wondrpak had been implanted.
In another seiries Ward's Waondrpak was implanted against bone for three days, then re-operated to remove the dressing and the defect allowed to heal for 30 days. The test group exhibited empty bone lacunae and the repair of the defect was retarded or lacking. 相似文献
In one series the dressings remained in situ for 3, 7, 14, 30 and 90 days. Osteocyte damage of varying extent was recorded for all materials. Remodelling of the bone surface adjacent to the dressing was observed. Bone resorption was never foud in the gournd defect produced to denude the bone tissue, but repair of the defect by bone formation was observed after long observation periods. This repair was retarded in some animals were Ward's Wondrpak had been implanted.
In another seiries Ward's Waondrpak was implanted against bone for three days, then re-operated to remove the dressing and the defect allowed to heal for 30 days. The test group exhibited empty bone lacunae and the repair of the defect was retarded or lacking. 相似文献
19.
20.
Posterior cranial fossa dimensions in the Chiari I malformation: Relation to pathogenesis and clinical presentation 总被引:8,自引:0,他引:8
Summary Skull dimensions were measured on lateral skull radiographs in 33 adult patients with MRI-verified Chiari I malformations and in 40 controls. The posterior cranial fossa was significantly smaller and shallower in patients than in controls. In the patients, there was a positive correlation between posterior fossa size and the degree of the cerebellar ectopia, which might indicate that a posterior cranial fossa which was originally too small had been expanded by the herniation of hindbrain structures at an early stage. Pyramidal signs and cerebellar symptoms and signs, which may be due to compression of neural structures, were associated with a large degree of ectopia and a relatively large posterior cranial fossa. Syringomyelia and headache, which may be due to the valve action of the herniated cerebellar tissue, were not associated with a particularly large posterior fossa or herniation. No special clinical presentation was associated with a very small posterior cranial fossa, which may indicate that a small posterior cranial fossa per se has little or no clinical significance, although it may be the primary developmental anomaly. 相似文献