首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   25756篇
  免费   2052篇
  国内免费   716篇
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
  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.
Fujii M  Akimura T  Ozaki S  Kato S  Ito H  Neshige R 《Epilepsia》1999,40(3):377-381
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.
Lamotrigine associated with insomnia   总被引:2,自引:0,他引:2  
Sadler M 《Epilepsia》1999,40(3):322-325
  相似文献   
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.
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.
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.
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号