全文获取类型
收费全文 | 25756篇 |
免费 | 2052篇 |
国内免费 | 716篇 |
专业分类
耳鼻咽喉 | 114篇 |
儿科学 | 647篇 |
妇产科学 | 200篇 |
基础医学 | 1929篇 |
口腔科学 | 459篇 |
临床医学 | 2338篇 |
内科学 | 2469篇 |
皮肤病学 | 327篇 |
神经病学 | 1931篇 |
特种医学 | 708篇 |
外国民族医学 | 5篇 |
外科学 | 1386篇 |
综合类 | 3503篇 |
现状与发展 | 3篇 |
一般理论 | 2篇 |
预防医学 | 3517篇 |
眼科学 | 414篇 |
药学 | 5042篇 |
58篇 | |
中国医学 | 2064篇 |
肿瘤学 | 1408篇 |
出版年
2024年 | 67篇 |
2023年 | 372篇 |
2022年 | 618篇 |
2021年 | 839篇 |
2020年 | 962篇 |
2019年 | 829篇 |
2018年 | 783篇 |
2017年 | 918篇 |
2016年 | 953篇 |
2015年 | 899篇 |
2014年 | 1649篇 |
2013年 | 2133篇 |
2012年 | 1452篇 |
2011年 | 1541篇 |
2010年 | 1200篇 |
2009年 | 1192篇 |
2008年 | 1156篇 |
2007年 | 1182篇 |
2006年 | 1042篇 |
2005年 | 903篇 |
2004年 | 765篇 |
2003年 | 712篇 |
2002年 | 589篇 |
2001年 | 476篇 |
2000年 | 412篇 |
1999年 | 328篇 |
1998年 | 338篇 |
1997年 | 350篇 |
1996年 | 290篇 |
1995年 | 246篇 |
1994年 | 266篇 |
1993年 | 242篇 |
1992年 | 253篇 |
1991年 | 234篇 |
1990年 | 206篇 |
1989年 | 203篇 |
1988年 | 202篇 |
1987年 | 189篇 |
1986年 | 181篇 |
1985年 | 194篇 |
1984年 | 205篇 |
1983年 | 112篇 |
1982年 | 159篇 |
1981年 | 107篇 |
1980年 | 118篇 |
1979年 | 101篇 |
1978年 | 71篇 |
1977年 | 74篇 |
1976年 | 62篇 |
1975年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A method is described for investigating life course influences on health in early old age. The lives of some 300 individuals at present aged 65-75 y have been reconstructed from the archived records of a pre-WWII survey, in which they took part as children, and from lifegrid interviews with the same individuals 60 y later. Despite loss to study at several points those interviewed are shown to be representative of the British population socio-demographically, in comparison with the 1931 and 1991 decennial censuses, and physically, in comparison with the Health Survey for England. Bias is conservative because the most disadvantaged were disproportionately affected by loss to follow-up through death and because non-responders to interview were more disadvantaged as children than the interviewees. Representativeness and conservative bias, it is argued, justify the use of these data for investigating life course influences on health in early old age. 相似文献
82.
RATIONALE AND OBJECTIVES: The authors evaluated the cardiac tolerability of paramagnetic contrast agents for magnetic resonance (MR) angiography in an in vitro model of ischemic rat heart. MATERIALS AND METHODS: The left anterior descending coronary artery was temporarily occluded in a perfused rat heart model to induce cardiac ischemia and reperfusion. A dose of 0.4 mL of gadobenate dimeglumine, of gadopentetate dimeglumine, or of D-mannitol was injected directly into the aorta both during the ischemia and during the reperfusion period. The left ventricular pressure and heart rate were recorded. RESULTS: Myocardial ischemia resulted in decreased cardiac activity, with a reduction in left ventricular pressure and heart rate. A further decrease in cardiac activity was temporarily induced by injection of contrast medium during both the ischemic and early reperfusion phases. Less marked responses were induced by a hyperosmolal solution of mannitol. CONCLUSION: These results suggest that the transient cardiac effects induced by bolus injection of paramagnetic contrast medium may be regarded as the combined effects of the osmotoxicity of the contrast medium solution and the chemotoxicity of the contrast medium molecule. 相似文献
83.
We present an unusual case of a patient who was diagnosed with temporal lobe epilepsy and whose seizures were reduced markedly after excision of an angiographically occult arteriovenous malformation (AVM) located in the left medial parietal lobe. A 38-year-old man had complex partial seizures characterized by motionless staring with oroalimentary and behavioral automatisms since the age of 15 years. Magnetic resonance imaging (MRI) demonstrated a small lesion extending from the left posterior cingulate gyrus to the precuneus. There was no MRI evidence of mesial temporal sclerosis. Intracranial EEG recordings showed ictal onset from the left medial parietal lobe propagating to the medial temporal lobes. Clinical signs appeared when these discharges reached the temporal lobes. After excision of the lesion (which was histologically confirmed as an AVM), together with the marginal cortex, seizures were reduced significantly. Careful diagnostic evaluation of lesions such as the this one may reveal an epileptogenic lesion (zone) far from the region where scalp ictal discharges seem to arise. In our case, we hypothesize that false localization was due to propagation of ictal discharges from the parietal focus through the limbic system. 相似文献
84.
Jilek-Aall L 《Epilepsia》1999,40(3):382-386
Epilepsy when manifested as grand mal seizure provokes strong and ambivalent feelings in those witnessing it. Terms such as morbus sacer, denoting both a sacred and demoniac condition, or folk names indicating divine punishment, have expressed these feelings in European societies from antiquity to the Middle Ages and beyond. An atmosphere of fear, shame and mysticism surrounds epilepsy even in our days in many non-Western and also in Western cultures. In the course of work and studies in Tanzania, where I organized the Mahenge Clinic for Epilepsy in 1960, and in other parts of Africa, I found that epilepsy is conceived of as an "African' affliction, a manifestation of supernatural forces that makes it difficult to reach epilepsy sufferers with modern medical treatment. Epilepsy is traditionally looked on as caused by ancestral spirits or attributed to possession by evil spirits. It is also thought to be due to witchcraft, and "poisoning," and often taken to be contagious. Epilepsy may, under Christian missionary teaching, have come to be considered as due to demoniac possession or divine punishment for sins, in accordance with biblical examples. In many parts of Africa, syncretic amalgamation of indigenous traditions with Judeo-Christian doctrines influenced popular attitudes toward epilepsy. We demonstrated that persistent efforts at health education in the context of organized treatment of epilepsy can result in a change of popular notions about epilepsy and consequently lead to significant improvement in the quality of life of epilepsy sufferers. 相似文献
85.
86.
The brain derived peptidergic drug Cerebrolysin has been found to support the survival of neurons in vitro and in vivo. Positive effects on learning and memory have been demonstrated in various animal models and also in clinical trials. In the present study the effects of early postnatal administration of Cerebrolysin (Cere, 10 mg/ml peptides) or an enriched peptide fraction of Cere (E021, 80.6 mg/ml peptides) were investigated in young, young adult, and old adult rats. Rat pups received the drugs or saline for control on postnatal days 1–7. The animals were tested in the Morris water maze (MWM) either in the 5th week, in the 3rd or the 16th month of life for 6 consecutive days (test days 1–6), eight trials per day. In order to prevent the chance finding of the hidden platform, the rigid underwater platform was replaced by a collapsible island, resting at the bottom of the pool. The platform was raised when the animal stayed in the target area for 2 s. In the young and young adult rats both Cere and E021 treated rats showed shorter escape latencies than saline treated controls on all 6 test days. No significant differences in the swimming speed were evaluated for the young rats, although in 3-month-old drug-tested animals a moderate increase of the swimming speed was investigated. For 16-month-old animals no significant differences in either escape latencies or swimming speed was found. Summarizing, early postnatal application of Cere or E021 improved the spatial learning and memory of young rats and led to long-lasting behavioural effects at least up to 3 months after treatment. 相似文献
87.
R. B. Dickson M. D. Johnson M. Maemura J. Low 《Breast cancer research and treatment》1996,38(1):121-132
Summary Most of the pharmaceuticals in clinical practice today for treatment of breast and other cancers are cytotoxic or cytostatic inhibitors of tumor growth. While this type of drug has found its place, along with surgery and radiotherapy, in treatment of disease, the breast cancer death rate has not decreased. This appears to be the result of rising incidence, resistance to therapy, and metastasis of the disease. Since distant metastasis (usually indicated by lymph node involvement) of breast cancer is related only indirectly to tumor size, it would appear that a concerted effort should be made to discover drugs which directly interfere with this complex process. Metastasis appears to depend upon tumor cell motility, dedifferen-tiation, local invasion, and angiogenesis. Significant progress has been recently made in the creation of new animal models of metastasis and in identifying several new drugs which may be suitable for clinical inhibition of this process. This article reviews current findings on anti-invasion/metastasis drugs with a focus on breast cancer.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb. 相似文献
88.
H. Savolainen R. Tenhunen E. Elovaara A. Tossavainen 《International archives of occupational and environmental health》1980,46(1):87-92
Summary Adult female NMRI mice exposed four times to 100 ppm hydrogen sulfide vapour for 2 h at 4-day intervals showed increasing inhibition of the cerebral cytochrome oxidase activity. Cerebral RNA decreased significantly after the fourth exposure. This change was accompanied by the reduced orotic acid uptake in the RNA fraction. At the same time, 2,3-cyclic nucleotide 3-phosphohydrolase activity used as a marker for glia increased. Acetylcholine esterase activity remained unchanged. The initial exposures also caused an increase in the superoxide dismutase activity and an increase in the glutathione concentration. The latter effects were abolished in the third and fourth exposures. The present data seem to indicate that the biochemical effects of repeated subclinical hydrogen sulfide intoxications are cumulative. 相似文献
89.
Prenatal administration of high doses of tricyclic antidepressants have been reported to produce teratogenic and behavioral effects in rat offspring. In the present work, behavioral abnormalities are described in offspring of rats treated with therapeutic doses of chlorimipramine (CIM) during pregnancy (CIM-P), lactation (CIM-L) and during the whole pregnancy-lactation period (CIM-PL). CIM-P treatment did not produce teratogenic effects, did not affect number or body weight of pups at birth and did not induce neonatal mortality. At 2 months of age, the CIM-P males showed a significant increase in digging and grooming (familiar environment test), a decrease in exploration (novel environment test) and a decrease in active social interactions (social behavior test). Females were more resistant than males to the prenatal CIM treatment. The results suggest increased emotionality in CIM-P pups. Some behavioral abnormalities were also observed in the tests performed at 4 months of age. CIM-L treatment had minor effects on litter behavior. CIM-PL treatment potentiated the effects of the CIM-P treatment. In the CIM-PL males, impairment of exploration of a novel environment still remained in the tests performed at 4 months of age. It is speculated that when prenatal brain development is altered by CIM, further postnatal treatment may impair compensatory processes occurring in early postnatal life. 相似文献
90.
D. Rehn G. Hennings W. Nocker W. Diebschlag 《European journal of clinical pharmacology》1991,40(6):625-627
Summary O-(-hydroxyethyl)-rutosides (HR) is used for the treatment of disorders of the venous and microcirculatory systems. In order to evaluate the time course of its activity, the effect of HR on a provocation model of orthostatic oedema in healthy volunteers was used. After a 2 week placebo run-in period, 16 healthy volunteers were randomized to HR (2 tablets of 500 mg/day) of placebo for a further 3 weeks, in a double-blind parallel design. Oedema was provoked by standing motionless for 1 h, with measurement of leg volume before and afterwards. The procedure was undertaken at entry to the study and then weekly during the entire 5 week period.There were no significant differences in the extent of oedema produced by the orthostatic challenge during the 2 week run-in period or in the subjects who continued on placebo (90 arbitrary units i.e. 48 ml). During the 3 week treatment with HR, however, there was a progressive reduction (–1.1, –5.9, and –7.6 arbitrary units after 1, 2, and 3 weeks, respectively) in the volume of induced oedema, which was significant after 2 and 3 weeks of treatment compared to the placebo group. 相似文献