全文获取类型
收费全文 | 10292篇 |
免费 | 626篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 123篇 |
儿科学 | 238篇 |
妇产科学 | 250篇 |
基础医学 | 1476篇 |
口腔科学 | 153篇 |
临床医学 | 943篇 |
内科学 | 2449篇 |
皮肤病学 | 216篇 |
神经病学 | 941篇 |
特种医学 | 231篇 |
外科学 | 1288篇 |
综合类 | 151篇 |
一般理论 | 12篇 |
预防医学 | 703篇 |
眼科学 | 238篇 |
药学 | 889篇 |
中国医学 | 27篇 |
肿瘤学 | 624篇 |
出版年
2023年 | 56篇 |
2022年 | 116篇 |
2021年 | 230篇 |
2020年 | 106篇 |
2019年 | 152篇 |
2018年 | 200篇 |
2017年 | 154篇 |
2016年 | 191篇 |
2015年 | 225篇 |
2014年 | 291篇 |
2013年 | 409篇 |
2012年 | 579篇 |
2011年 | 597篇 |
2010年 | 291篇 |
2009年 | 333篇 |
2008年 | 559篇 |
2007年 | 600篇 |
2006年 | 553篇 |
2005年 | 559篇 |
2004年 | 561篇 |
2003年 | 494篇 |
2002年 | 510篇 |
2001年 | 234篇 |
2000年 | 202篇 |
1999年 | 169篇 |
1998年 | 97篇 |
1997年 | 79篇 |
1996年 | 75篇 |
1995年 | 65篇 |
1994年 | 76篇 |
1993年 | 77篇 |
1992年 | 150篇 |
1991年 | 151篇 |
1990年 | 118篇 |
1989年 | 138篇 |
1988年 | 124篇 |
1987年 | 118篇 |
1986年 | 118篇 |
1985年 | 78篇 |
1984年 | 86篇 |
1983年 | 72篇 |
1982年 | 75篇 |
1981年 | 56篇 |
1980年 | 54篇 |
1979年 | 50篇 |
1978年 | 48篇 |
1977年 | 45篇 |
1976年 | 43篇 |
1975年 | 63篇 |
1971年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 172 毫秒
61.
Pramod K Pal Joanne Leung Katya Hedrich Ali Samii Abraham Lieberman Paul A Nausieda Donald B Calne Xandra O Breakefield Christine Klein A Jon Stoessl 《Movement disorders》2002,17(4):789-794
There are few reports of positron emission tomography (PET) in juvenile parkinsonism (JP). We report on the results of (18)F-6-fluoro-L-dopa (FD) PET in a 14-year-old patient with JP of 5 years duration associated with atypical features. This is the youngest subject to be investigated to date. There was a severe asymmetric reduction in striatal FD uptake, with a rostrocaudal gradient in the putamen similar to that seen in adult-onset idiopathic parkinsonism. Extensive DNA analysis in this patient did not show mutations in the parkin gene. 相似文献
62.
F A Abraham A Spierer M Blumenthal 《Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift für Augenheilkunde》1987,194(1):40-43
An accidental deep intraorbital penetration of a radio antenna tip damaged the optic nerve and caused immediate amaurosis in a 19-year-old female with normal funduscopic, electroretinographic and computerized tomographic orbital findings. A small visual-evoked potential (VEP) recorded within 2 h of injury and in the following days revealed persistent electrical nerve conduction despite loss of vision and afferent pupillary reaction. The VEP constituted the only anticipating sign for the visual recovery which occurred after 3 days. Further increase of the VEP amplitudes preceded the visual improvement, resulting, finally, in 6/24 visual acuity with only lower nasal quadrant scotoma and slight optic disk pallor. 相似文献
63.
A significant increase of cutaneous laser Doppler flowmetry was found before blood flow decreases with increasing pressure during a 5 mmHg min−1 increase of pressure strain on the finger. Pre-treatment with a local anaesthetic or chronically applied capsaicin, resulted in the disappearance of the vasodilatory response. These results suggest an original vasodilatory axon reflex response to non-noxious pressure strain which is initiated by capsaicin-sensitive nerve terminals in the human skin. 相似文献
64.
N-methyl-D-aspartate (NMDA) receptor/channel antagonists have previously been shown to impair spatial working memory and hippocampal long-term potentiation. The present experiment investigated the effects of a variety of doses of NMDA antagonists on a working memory task in rats involving an auditory delayed conditional discrimination. Signal detection analysis and an exponential memory decay model were used to extract independent measures of stimulus discriminability and rate of forgetting. A competitive NMDA antagonist, (CPP, 0.33, 1.0, 10.0 mg/kg, IP) produced a reduction in discriminability which was linearly related to log dose, but which was only clear at the 10 mg/kg dose. Rate of forgetting was not increased by any dose. Similar results were obtained with a non-competitive antagonist (MK-801, 0.1, 0.33 mg/kg, IP). These data suggest that doses of NMDA receptor channel antagonists sufficient to disrupt hippocampal long-term potentiation and radial arm maze performance will also disrupt delayed conditional discrimination. The effect on delayed conditional discrimination is due to a disruption of stimulus discriminability and not to an increased rate of forgetting. The extent to which these effects relate to the reported changes in hippocampal long-term potentiation and radial arm maze performance remains to be determined. 相似文献
65.
Effects of chemical mediators of anaphylaxis on ciliary function 总被引:2,自引:0,他引:2
Adam Wanner M.D. David Maurer Ph.D. William M. Abraham Ph.D. Zsolt Szepfalusi Marek Sielczak M.D. 《The Journal of allergy and clinical immunology》1983,72(6):663-667
We assessed the effects of selected chemical mediators of anaphylaxis on CBF in vitro. Ciliated epithelial cells were obtained from the trachea of conscious sheep with a cytology brush and suspended in a perfusion chamber containing KH. Ciliary activity was viewed microscopically and recorded on videotape for subsequent slow-motion analysis of CBF. Prostaglandin E1 (10(-8) M to 10(-6) M), prostaglandin E2 (10(-10) M to 10(-6) M), and leukotriene-C4 (10(-8) M) increased CBF between 7% and 33%. Histamine caused ciliostimulation only at the relatively high concentrations above 10(-5) M (7% increase in CBF), whereas prostaglandin F2 alpha (10(-10) M and 10(-6) M) was without effect. In no preparation was ciliary discoordination observed. These findings indicate that several chemical mediators of anaphylaxis stimulate CBF and that the previously described impairment of mucociliary transport in stable allergic asthma or antigen-induced bronchoconstriction is probably not caused by a primary alteration of ciliary function. 相似文献
66.
Immunoglobulin E and eosinophil-dependent protective immunity to larval Onchocerca volvulus in mice immunized with irradiated larvae
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Abraham D Leon O Schnyder-Candrian S Wang CC Galioto AM Kerepesi LA Lee JJ Lustigman S 《Infection and immunity》2004,72(2):810-817
Mice immunized with irradiated Onchocerca volvulus third-stage larvae developed protective immunity. Eosinophil levels were elevated in the parasite microenvironment at the time of larval killing, and measurements of total serum antibody levels revealed an increase in the immunoglobulin E (IgE) level in immunized mice. The goal of the present study was to identify the role of granulocytes and antibodies in the protective immune response to the larval stages of O. volvulus in mice immunized with irradiated larvae. Immunity did not develop in mice if granulocytes, including both neutrophils and eosinophils, were eliminated, nor did it develop if only eosinophils were eliminated. Moreover, larvae were killed in na?ve interleukin-5 transgenic mice, and the killing coincided with an increase in the number of eosinophils and the eosinophil peroxidase (EPO) level in the animals. To determine if EPO was required for protective immunity, mice that were genetically deficient in EPO were immunized, and there were no differences in the rates of parasite recovery in EPO-deficient mice and wild-type mice. Two mouse strains were used to study B-cell function; micro MT mice lacked all mature B cells, and Xid mice had deficiencies in the B-1 cell population. Immunity did not develop in the micro MT mice but did develop in the Xid mice. Finally, protective immunity was abolished in mice treated to eliminate IgE from the blood. We therefore concluded that IgE and eosinophils are required for adaptive protective immunity to larval O. volvulus in mice. 相似文献
67.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) affects the thyroid morphologically and/or functionally in adult animals. Recently, the National Toxicology Program conducted a 2-year gavage study of TCDD in female Harlan Sprague-Dawley rats. The only treatment-related alterations found in thyroid follicles were decreased luminal size and increased height of the follicular epithelial cells, without prominent protrusion into the lumen. The present study elucidated the nature of these follicular lesions. Thyroid glands of 10 rats each from the control, high (100 ng/kg/day)-dose, and stop-study (100 ng/kg/day, 30 weeks; vehicle to study termination) groups in the 2-year study were evaluated microscopically. Twenty randomly selected follicles were measured morphometrically in each animal. TCDD treatment significantly decreased the mean ratio of luminal/epithelial areas and increased the mean sectional epithelial height of the high-dose group compared to controls. Thyroid sections were immunostained with antibody against minichromosome maintenance (MCM) proteins, a novel cell-cycle biomarker. The MCM labeling index of the high-dose group was significantly higher than that of the control; however, the TUNEL labeling index was also higher in the high-dose group than the control. All data from the stop group were comparable to those from controls. These results indicate that the follicular cell response was hypertrophic and reversible. This information should contribute to diagnosis of nonneoplastic thyroid follicular lesions in rats. 相似文献
68.
The time for reproduction in mammals largely depends on the availability of water and food in their habitat. Therefore, in regions where rains are limited to definite seasons of the year, mammals presumably will restrict their breeding correspondingly. But while mammals living in predictable ecosystems would benefit by timing their season to an ultimate predictable cue, such as photoperiod, in unpredictable ecosystems (e.g., deserts) they will need to use a more proximate signal. We suggest a mechanism by which water shortage (low water content in plants) could act as a proximate cue for ending the reproductive season. The golden spiny mouse (Acomys russatus), a diurnal rodent living in extreme deserts, may face an increased dietary salt content as the summer progresses and the vegetation becomes dry. Under laboratory conditions, increased diet salinity lead to reproductive hiatus in females, notable in imperforated vagina, and a significant decrease in the ovaries, uteri, and body masses. In females treated with vasopressin (VP), a hormone expressed during water stress, the uteri and body masses have decreased significantly, and the ovaries exhibited an increased number of atretic follicles. VP has also led to a significant decrease in relative medullary thickness (RMT) of the kidney. It is thus suggested that VP could act as a modulator linking the reproductive system with water economy in desert rodents, possibly through its act on the energetic pathways. 相似文献
69.
The NTP has a long history of using Fischer rats and has compiled a large database of incidences of lesions seen in control animals. Such a database is lacking for Harlan Sprague-Dawley (SD) rats. The intention of this paper is to report spontaneous lesions observed in female vehicle control Harlan SD rats, and to compare the incidence in 2 strains of rats (Fischer and Harlan SD) used in NTP studies. Female Harlan SD rats served as the test animals for a special series of 2-year studies. Male rats were not used in these studies. Complete histopathology was performed on all animals, and the pathology results underwent comprehensive NTP pathology peer review. The most commonly observed neoplasms in these female control Harlan SD rats were mammary gland fibroadenoma (71%), tumors of the pars distalis of the pituitary (41%) and thyroid gland C-cell tumors (30%). Female Fischer rats had incidences of 44% for mammary gland fibroadenomas, 34% for tumors of the pars distalis, and 16% for thyroid gland C-cell tumors. Fischer rats had a 15% incidence of clitoral gland tumors, while the Harlan SD rats had an incidence of < 1%. In contrast to Fischer F344 rats, the Harlan SD rats had a high incidence of squamous metaplasia of the uterus (44.2%). Squamous metaplasia is not a lesion commonly observed in NTP control Fischer rats. The Harlan SD rats had a very low incidence of mononuclear cell leukemia (0.5%), compared with an incidence of 24% in female Fischer rats. 相似文献
70.