全文获取类型
收费全文 | 175869篇 |
免费 | 794篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 1137篇 |
儿科学 | 6622篇 |
妇产科学 | 2996篇 |
基础医学 | 16548篇 |
口腔科学 | 1544篇 |
临床医学 | 12401篇 |
内科学 | 30871篇 |
皮肤病学 | 675篇 |
神经病学 | 16433篇 |
特种医学 | 8986篇 |
外科学 | 28880篇 |
综合类 | 2316篇 |
预防医学 | 18048篇 |
眼科学 | 2743篇 |
药学 | 9435篇 |
中国医学 | 624篇 |
肿瘤学 | 16408篇 |
出版年
2023年 | 56篇 |
2022年 | 89篇 |
2021年 | 122篇 |
2020年 | 66篇 |
2019年 | 76篇 |
2018年 | 21973篇 |
2017年 | 17396篇 |
2016年 | 19564篇 |
2015年 | 925篇 |
2014年 | 816篇 |
2013年 | 782篇 |
2012年 | 6962篇 |
2011年 | 21007篇 |
2010年 | 18791篇 |
2009年 | 11499篇 |
2008年 | 19477篇 |
2007年 | 21657篇 |
2006年 | 506篇 |
2005年 | 2111篇 |
2004年 | 3325篇 |
2003年 | 4305篇 |
2002年 | 2437篇 |
2001年 | 271篇 |
2000年 | 414篇 |
1999年 | 161篇 |
1998年 | 198篇 |
1997年 | 199篇 |
1996年 | 85篇 |
1995年 | 97篇 |
1994年 | 94篇 |
1993年 | 57篇 |
1992年 | 41篇 |
1991年 | 89篇 |
1990年 | 125篇 |
1989年 | 86篇 |
1988年 | 62篇 |
1987年 | 51篇 |
1986年 | 36篇 |
1985年 | 43篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1980年 | 43篇 |
1974年 | 23篇 |
1969年 | 26篇 |
1938年 | 60篇 |
1937年 | 25篇 |
1935年 | 22篇 |
1934年 | 30篇 |
1932年 | 56篇 |
1930年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Martha Motono Chojniak Rubens Chojniak Ines Nobuko Nishimoto Norma Allemann Clélia Maria Erwenne 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2011,249(12):1859-1865
Background
The treatment of small choroidal melanoma is controversial. Thermal laser-induced treatment is utilized by some centers but there is still sparse literature about the subject, mainly with short-term follow-up time. The efficacy of transpupillary thermotherapy (TTT) for the treatment of small choroidal melanomas was evaluated. 相似文献952.
953.
Kerstin Steindl-Kuscher Michael E. Boulton Paulina Haas Astrid Dossenbach-Glaninger Hans Feichtinger Susanne Binder 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2011,249(8):1195-1200
Background
To analyze whether epidermal growth factor (EGF) exerts regulatory effects on proliferation and differentiation in ARPE19 cells after different incubation periods (24 vs. 48 h) for obtaining ideal conditions for feasible rejuvenation and autologous transplantation of retinal pigment epithelial cells (RPE cells). 相似文献954.
955.
Our purpose was to compare the effects of percutaneous radiofrequency ablation (RFA) combined with percutaneous ethanol injection (PEI) on the extent of ablation in in vivo rabbit liver tissue as compared with either therapy alone. Twenty-two New Zealand white rabbits were included in this study and allocated into three groups: group A: conventional RFA (n = 6); group B: PEI (n = 6); group C: combined RFA and PEI (n = 10). For combined RFA and PEI, under ultrasound guidance, 1 mL of absolute ethanol was injected into the target area of the liver parenchyma through a 21-gauge Chiba needle before performing RFA. RFA was performed using a 17- gauge internally cooled electrode with 1-cm active tip, and RF energy (30 W) was applied for 3 minutes, with or without ethanol injection. After RFA or PEI, contrast-enhanced computed tomography and CT-pathologic correlation were performed. The short- axis and long-axis diameters of thermal lesions of each group were compared. All procedures were technically successful and a total of 38 lesions were produced. The mean short-axis and long-axis diameter of the coagulation necrosis in rabbits of group C (combination of RFA and PEI), were significantly larger than those of other groups: group A: 10.3 ± 2 mm and 11.4 ± 2 mm; group B: 3.1 ± 1 mm and 4.3 ± 2 mm; group C: 12.8 ± 3 mm and 17.8 ± 6 mm (p < 0.05). On contrast-enhanced CT scan, the lesions of rabbits of the group C appeared to be more frequently irregular compared to those of group A (20% in group A vs. 67% in group C). There were three complications including two localized hematomas and one cardiopulmonary failure. Combined RFA and PEI could increase the dimension of coagulation necrosis without increasing complications and therefore, may be successfully used for treating larger lesions. 相似文献
956.
Purpose
The aim of this study was to compare acoustic radiation force impulse (ARFI) results between livers with and without fat deposition. 相似文献957.
958.
959.
Historical record and source apportionment of polycyclic aromatic hydrocarbons in the Lianhuan Lake sediments 总被引:1,自引:0,他引:1
Polycyclic aromatic hydrocarbons (PAHs) in a sediment core from the north Lianhuan Lake were collected to investigate its
historical changes in the last one hundred years and its possible influence on ecological system in the lake. GC–MS was used
to determine the concentrations of PAHs, and sediment chronological age was examined by 137Cs dating approach. The concentrations of 16 different kinds of PAHs in the sediment samples ranged from 297 to 1,327 ng g−1, and the low molecular weight (LMW) were predominant. The intensification of industrial and anthropogenic activities in the
Daqing oil field may play the key role in the increase of PAHs concentrations in the late 1950s. To the early 1980s, the PAHs
concentrations significantly decreased due to the grain size coarsening in the sediment samples, which was confirmed by the
precipitation information. The 5–6 rings PAHs concentrations increased in the early 1980s may be attributed to the consumption
of petroleum, coal and wood. The results showed that both the PAHs historical record and current concentrations may cause
some influence on the Lianhuan Lake ecological system. The toxicology research on this ecological system should be done in
the further investigations for determining the PAHs damage on human and ecological system health. 相似文献
960.
Anthropogenic sources of nitrogen that pollute bodies of water can have toxic and sub-lethal effects on amphibians. It has
been hypothesized that such exposure may promote local adaptation, that is, selection for higher tolerance in individuals
in populations exposed to pollutants. We tested this hypothesis with respect to the Natterjack toad (Bufo calamita Laurenti, 1768), by comparing the nitrate dose response of tadpoles from eight populations (doses: 0, 50, 100, 500 and 1000 mg/l
nitrate) from relatively unpolluted and intensively farmed environments. We evaluated the effect of nitrate exposure by observing
the behavior (movements) of tadpoles exposed to different concentrations of nitrates. Exposure to high nitrate levels did
not cause tadpole mortality in the populations used in our experiments; however, we did observe changes in activity for all
populations, with these changes being either dose-related responses (decreased activity after exposure to 500 or 1000 mg/l),
or more complex responses (increased activity when exposed to 50 or 100 mg/l nitrate, followed by decreased activity at higher
concentrations). Natterjack toad tadpoles exhibited variable behavioural responses among the tested populations. Although
these populations were selected on the basis of their potential agrochemical contamination, the observed variation in population
tolerance was not related to the parameters used to estimate this contamination in these breeding sites. Possible explanations
for this apparent lack of local adaptation in B. calamita tadpoles include inadequate estimates of the toads’ actual nitrate exposure in the field, and the biological characteristics
of B. calamita, which may limit the effects of exposure or favor phenotypic plasticity. 相似文献