全文获取类型
收费全文 | 3433448篇 |
免费 | 250932篇 |
国内免费 | 9215篇 |
专业分类
耳鼻咽喉 | 46438篇 |
儿科学 | 113222篇 |
妇产科学 | 95782篇 |
基础医学 | 481973篇 |
口腔科学 | 94797篇 |
临床医学 | 314762篇 |
内科学 | 673998篇 |
皮肤病学 | 81422篇 |
神经病学 | 282578篇 |
特种医学 | 130820篇 |
外国民族医学 | 1111篇 |
外科学 | 512590篇 |
综合类 | 74076篇 |
现状与发展 | 7篇 |
一般理论 | 1336篇 |
预防医学 | 267659篇 |
眼科学 | 77723篇 |
药学 | 248367篇 |
8篇 | |
中国医学 | 7251篇 |
肿瘤学 | 187675篇 |
出版年
2019年 | 27484篇 |
2018年 | 38540篇 |
2017年 | 29583篇 |
2016年 | 34004篇 |
2015年 | 38291篇 |
2014年 | 53335篇 |
2013年 | 80064篇 |
2012年 | 106850篇 |
2011年 | 113301篇 |
2010年 | 67895篇 |
2009年 | 64785篇 |
2008年 | 105300篇 |
2007年 | 111706篇 |
2006年 | 113552篇 |
2005年 | 109266篇 |
2004年 | 104780篇 |
2003年 | 101052篇 |
2002年 | 97635篇 |
2001年 | 165428篇 |
2000年 | 169490篇 |
1999年 | 142508篇 |
1998年 | 41225篇 |
1997年 | 36703篇 |
1996年 | 36729篇 |
1995年 | 35517篇 |
1994年 | 32430篇 |
1993年 | 30347篇 |
1992年 | 110030篇 |
1991年 | 105629篇 |
1990年 | 102351篇 |
1989年 | 98599篇 |
1988年 | 90436篇 |
1987年 | 88610篇 |
1986年 | 82992篇 |
1985年 | 79420篇 |
1984年 | 59547篇 |
1983年 | 50469篇 |
1982年 | 30179篇 |
1981年 | 26902篇 |
1979年 | 52636篇 |
1978年 | 37259篇 |
1977年 | 31395篇 |
1976年 | 29245篇 |
1975年 | 30834篇 |
1974年 | 36723篇 |
1973年 | 35101篇 |
1972年 | 32992篇 |
1971年 | 30511篇 |
1970年 | 28357篇 |
1969年 | 27002篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
M Yoshino Y Sakaguchi N Kuriya Y Ohtani F Yamashita T Hashimoto K Oyanagi K Tada K Narisawa T Kitagawa 《Neuropediatrics》1991,22(4):198-202
A nationwide survey of transient hyperammonemia in newborns was carried out in Japan. A total of 18 patients, consisting of 12 male and 6 female infants, were reported from 11 facilities. These neonates exhibited hyperammonemia with plasma ammonia levels in the range from 124 to 6256 micrograms/dl. Four newborn infants of the 18 died in the neonatal period, and an additional one died in the early infancy. Among the 13 infants who were alive at the time of this survey, 6 had neurological sequelae, including mental retardation, spastic quadriplegia and epilepsy. The multivariate analysis revealed that the Apgar score at 1 minute, peak plasma ammonia concentration, birth weight and sex were significant factors affecting the prognosis of life. 相似文献
952.
B Lu J M Lee R Elliott C F Dreyfus J E Adler I B Black 《Brain research. Molecular brain research》1991,11(3-4):359-362
Nerve growth factor (NGF) gene expression in central nervous system (CNS) glia appears to be associated with active glial growth. To study the underlying molecular mechanisms, we examined the effects of a number of growth-related factors on NGF mRNA expression in glial cultures. Our results suggest that glial membrane interaction, as a consequence of growth, actively inhibits NGF gene expression in CNS glia. 相似文献
953.
R Shirane H Shimizu M Kameyama P R Weinstein 《Journal of cerebral blood flow and metabolism》1991,11(6):949-956
A new model of temporary complete cerebral ischemia was developed and tested in 64 rats. With use of microsurgical techniques, both pterygopalatine and external carotid arteries were occluded and the basilar artery was coagulated to reduce potential collateral CBF during ischemia. After this preliminary five-vessel occlusion, temporary global ischemia was induced by occluding the common carotid arteries (CCAs) with microclips. To validate the method, CBF was measured autoradiographically in 24 anatomical regions at death after 5 min of ischemia or after 15 min of ischemia followed by 5 min of reperfusion. Mean arterial blood pressure and arterial blood gases remained stable under controlled endotracheal ventilation and anesthesia (halothane, 70% N2O, and 30% O2) throughout the CBF experiments, except for a 10-15% increase in mean arterial blood pressure for 1-5 min after bilateral CCA occlusion. After the initial five-vessel occlusion, the EEG did not change, and local CBF levels were comparable to those in anesthetized non-surgical controls. When the CCAs were occluded, the EEG flattened rapidly; after 5 min of ischemia, autoradiography showed no detectable blood flow in the forebrain and cerebellum. The local CBF levels measured after 15 min of temporary global ischemia and 5 min of reperfusion demonstrated relatively homogeneous postischemic hyperperfusion; only two of eight rats had several 1- to 3-mm areas of no-reflow. Survival studies showed increasing motor impairment after 10, 15, 30, and 60 min of temporary CCA occlusion. Ischemic neuronal damage was observed histologically in the hippocampus and basal ganglia 24 h after 10 min of temporary ischemia.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
954.
3α-Hydroxy-5α-pregnan-20-one (HPO) is a progesterone metabolite which exhibits narcotic properties at high concentrations by interactions with the receptor for gamma-aminobutyric acid (GABA). The present investigation characterized low-dose effects of HPO on GABAA receptor binding, by determining the allosteric properties of HPO on the in vitro binding of 3H-muscimol to membrane fractions from the cerebella of ovariectomized rats. A newly developed method for tissue preparation was used to wash out endogenous ligands interfering with the assay. HPO reduced the affinity of 3H-muscimol to GABAA receptor sites by 52% and enhanced the number of accessible binding sites from 5.5±0.5 to 7.5±1.3 pmol/mg protein at subnanomolar (0.1 nM) HPO concentrations. The modulatory effects of HPO on GABAA receptor binding provide evidence that this pregnane steroid might be a physiologically relevant modulator of GABAergic neurotransmission. 相似文献
955.
D Mezzano G E del Pino M Montesinos M E García E Aranda A Foradori 《Thrombosis and haemostasis》1991,66(2):254-258
Thrombocytopenia was induced in mongrel dogs by two mechanisms: immunologically, by intravenous injection of heterologous antiplatelet antibody, and non-immunologically, by circulating the blood through glass beads in anesthetized animals. The platelet content of 5-HT was monitored before and during the recovery of the blood platelet counts. This period is associated with the normalization of the mean platelet survival time and with a progressive increase in the mean age of the circulating platelet population. A continuous increment in platelet 5-HT closely followed the increase in platelet counts in both models of thrombocytopenia, and a strong correlation was found between the platelet age and 5-HT content. These findings support the concept that platelets accumulate 5-HT during their physiological aging process, contradicting the notion that a negative balance in 5-HT content results at the end of their physiological lifespan in circulation. These results are not in conflict with the concept that circulating platelets release and re-uptake 5-HT. 相似文献
956.
C W Scott D P Blowers P T Barth M M Lo A I Salama C B Caputo 《Journal of neuroscience research》1991,30(1):154-162
Three isoforms of human tau protein were compared for their abilities to induce microtubule assembly. The three isoforms, tau 3 (tau containing three microtubule-binding domains), tau 4 (tau containing four microtubule-binding domains) and tau 4L (tau containing four microtubule binding domains plus a 58-amino-acid insert near the N-terminus) were expressed in E. coli and purified using ammonium sulfate precipitation, ion exchange, and size exclusion chromatography. All three isoforms induced microtubule assembly at micromolar concentrations and showed similar critical concentrations for assembly of 0.4-0.45 microM. However, tau 4 induced microtubule formation at a rate five- to tenfold faster than either tau 3 or tau 4L. The rate of microtubule elongation seen with tau 4 was twofold greater than with tau 3 or tau 4L, suggesting that the faster rate of microtubule assembly seen with tau 4 was due, at least in part, to faster elongation. Tau 4 induced a greater number of microtubules to form at steady state than did tau 3 or tau 4L. The microtubules generated with each tau isoform had similar steady-state length distributions and were equally susceptible to cold-induced disassembly. These results indicate that the additional microtubule-binding domain in tau 4 enhances microtubule assembly, while the 58-amino-acid insert negates the stimulatory effect of the fourth microtubule-binding domain. 相似文献
957.
958.
M B Taylor 《Postgraduate medicine》1991,89(8):40-2, 45-7
The spectrum of acne vulgaris is wide, ranging from minor comedones to devastating nodules and cysts. Appropriate therapy requires an understanding of the various types of lesions, their pathophysiology, and the rationale for treatment. Good patient rapport and communication are important, and close follow-up is necessary until the treatment regimen has stabilized. Timely referral to a dermatologist is essential when therapy is not effective. With effort, the treatment of acne can be quite rewarding for both patient and physician. 相似文献
959.
N M Whear J D Langdon D W Macpherson 《International journal of oral and maxillofacial surgery》1991,20(6):357-359
A new surgical technique for the treatment of recurrent temporomandibular joint subluxation or dislocation is described. Following a horizontal osteotomy and down-fracture of the articular eminence an inter-positional bovine cartilage xenograft is inserted in order to augment the vertical height of the eminence. The procedure combines simplicity with minimal post-operative morbidity. The increase in eminence height is both predictable and stable. 相似文献
960.
M C Plewa 《Emergency Medicine Clinics of North America》1991,9(4):827-852
Plain abdominal radiographs are rarely diagnostic when the patient presents with acute abdominal pain. Emergency physicians, therefore, should be aware of the appropriate indications and limitations of abdominal films in this setting and should be skilled in their interpretation to exclude the rare cases of pneumoperitoneum, pneumobilia, hepatic-portovenous gas, small and large bowel obstruction, toxic megacolon, volvulus and intramural gas. 相似文献