全文获取类型
收费全文 | 201431篇 |
免费 | 18499篇 |
国内免费 | 12123篇 |
专业分类
耳鼻咽喉 | 2177篇 |
儿科学 | 2139篇 |
妇产科学 | 2741篇 |
基础医学 | 24990篇 |
口腔科学 | 3543篇 |
临床医学 | 25271篇 |
内科学 | 30715篇 |
皮肤病学 | 2780篇 |
神经病学 | 10938篇 |
特种医学 | 8013篇 |
外国民族医学 | 97篇 |
外科学 | 21085篇 |
综合类 | 29650篇 |
现状与发展 | 39篇 |
一般理论 | 28篇 |
预防医学 | 12658篇 |
眼科学 | 5311篇 |
药学 | 21314篇 |
191篇 | |
中国医学 | 11205篇 |
肿瘤学 | 17168篇 |
出版年
2024年 | 743篇 |
2023年 | 3120篇 |
2022年 | 8278篇 |
2021年 | 10588篇 |
2020年 | 7736篇 |
2019年 | 6866篇 |
2018年 | 7277篇 |
2017年 | 6577篇 |
2016年 | 6503篇 |
2015年 | 9842篇 |
2014年 | 11815篇 |
2013年 | 11154篇 |
2012年 | 16249篇 |
2011年 | 17256篇 |
2010年 | 11053篇 |
2009年 | 8555篇 |
2008年 | 11311篇 |
2007年 | 10625篇 |
2006年 | 10087篇 |
2005年 | 9674篇 |
2004年 | 6332篇 |
2003年 | 5695篇 |
2002年 | 4755篇 |
2001年 | 3694篇 |
2000年 | 3861篇 |
1999年 | 3913篇 |
1998年 | 2341篇 |
1997年 | 2386篇 |
1996年 | 1819篇 |
1995年 | 1748篇 |
1994年 | 1533篇 |
1993年 | 931篇 |
1992年 | 1297篇 |
1991年 | 1139篇 |
1990年 | 914篇 |
1989年 | 862篇 |
1988年 | 774篇 |
1987年 | 654篇 |
1986年 | 468篇 |
1985年 | 413篇 |
1984年 | 198篇 |
1983年 | 169篇 |
1982年 | 102篇 |
1981年 | 130篇 |
1980年 | 81篇 |
1979年 | 112篇 |
1978年 | 60篇 |
1977年 | 57篇 |
1976年 | 47篇 |
1974年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
OBJECTIVES: To examine the effect of individual patient factors (age, parity, body mass index, menstrual cycle, menopause, hormone replacement therapy, bladder neck position and urethral mobility) on the appearance of Doppler flow in urethral vessels, to investigate the association between the Doppler flow parameters and intrinsic urethral function, storage and voiding, and to explore differences in the urethral vasculature between subjects with and without urodynamic stress incontinence (USI). METHODS: Over a 4-year period we prospectively performed imaging studies in 355 women, including 244 who denied any lower urinary tract symptoms within the previous 3 months (Group A) and 111 who had had lower urinary tract symptoms (Group B). Studies included morphologic assessment and Doppler flow investigation of the lower urinary tract. Vascular flow velocity and vessel density in the urethral vasculature were measured. For women in Group B, multichannel urodynamic studies were also performed. RESULTS: The urethral vasculature has five main branches of vessels. Their appearance was not affected by the menstrual cycle or menopause except for those of the anterior vaginal vessel and anterior branch of the middle urethral vessel. Other than that of the posterior urethral vessel, in which there was a correlation with parity, the resistance index (RI) was not affected by individual patient factors. However, there was a correlation between the vascular index (VI) and individual factors such as age (r = -0.336, P = 0.002), body mass index (r = -0.287, P = 0.028), menopause (r = -0.402, P < 0.001), and hormone replacement therapy (r = 0.392, P = 0.027). Only the VI and RI of the posterior urethral vessel correlated significantly with the urethral pressure profile. In subjects with lower urinary tract symptoms, the appearance of the urethral vasculature on power Doppler imaging and the corresponding RI and VI values were not correlated with objective evidence of USI. CONCLUSION: Patient factors may affect specific Doppler flow parameters of the urethral vasculature, which are related to intrinsic resting urethral closure. There is no difference in the appearance of the urethral vasculature in subjects with or without USI. 相似文献
62.
63.
本实验研究了兔视网膜中的方向选择性神经节细胞 (direction selective retinal ganglion cells,DS cells)树突野的分枝模式。测量了视网膜中方向选择性神经节细胞和作为经典分枝模式神经元代表的α神经节细胞的树突直径。发现 ,方向选择性神经节细胞的树突在分枝后直径达到 0 .5 μm,进一步分枝树突直径仍保持在 0 .5 μm左右 ,这样 ,在方向选择性神经节细胞树突野中大多数树突直径在 0 .5μm左右。而作为经典分枝模式神经元代表的α神经元的树突每次分枝后都逐级变细 ,最终直径达到 0 .5μm左右 ,这样 ,α神经节细胞的树突直径大部分都大于 0 .5μm。我们应用程序“NEU RON”对在两种神经元模型中 ,抑制点落于兴奋点与胞体之间 (proximal)和抑制点不落于兴奋点与胞体之间 (distal)这两种情况进行模拟。我们发现 ,当抑制点不落于兴奋点与胞体之间时 ,在方向选择性神经节细胞的树突分枝模型中 ,抑制效果更强。那么 ,将使得方向选择性神经节细胞对抑制点落于兴奋点和胞体之间的要求变得不是那么迫切。所以 ,方向选择性神经节细胞的这种独特分枝模式 ,也许可以避免或至少减轻其在发育中可能会产生的连线的复杂性。并且 ,我们对得出的结论进行了电路分析 ,对方向选择性神经节细胞这种独特的分枝模式具有的? 相似文献
64.
目的探讨用游离自体腹白线片修补急性十二指肠溃疡穿孔的应用价值。方法从2006年1月至2006年7月对13例用自体腹白线片修补急性十二指肠溃疡穿孔的病人的临床资料和随访情况进行回顾性分析,其中2例穿孔大于2cm2,平均手术时间60分钟,平均失血量20ml,平均住院天数9±1天。结果游离自体腹白线片修补急性十二指肠溃疡穿孔13例均痊愈出院。随访15天至6个月,无手术并发症。结论本方法操作较简单、安全、效果好,其适应症广,是一种可行的新方法。 相似文献
65.
66.
67.
68.
Jiyou Li Yuquan Xie Guizhi Shi Heling Sun Xinhua Ji Maolin Jin Boqin Yang Mingsheng Wang 《中国癌症研究》1992,4(2):10-12
In order to investigate the antagonistic effect of Glycyrrhiza Uralensis Fish (GUF) and Chelidonium maJus L (CML) on gastrccarcinogenesis
induced by MNNG in Wastar rats, we treated the rats with MNNG alone (group 1) and with MNNG plus GUF and CML (group 2 and
3) respectively. The incidence of infiltrating adenocarcinoma of the glandular stomach and duodenum in group 2 was significantly
lower than that in group 1 (26.7% vs. 67.8%). The differentiation and aggressivenees of carcinomas occured in group 2 were
much better and mild than those in group 1. Present study also demonstrated that the inhibitory effect of CML on proliferation
of human stomach carcinoma cell line MGC-803 was very remarkable; in addition, GUF and CML were able to antagonise the mutagenic
activation of MNNG. These results suggest that GUF and CML may be empoyed in prevention of gastric carcinoma. 相似文献
69.
T.-N. Wu Chen-Yang Shen Saou-Hsing Liou Guang-Yang Yang K.-N. Ko Show-Lin Chao Chao-Chun Hsu P.-Y. Chang 《International archives of occupational and environmental health》1997,69(6):386-391
To monitor the lead hazards in industries and to investigate the prevalence of elevated blood lead levels (BLLs) in lead-exposed
workers, a lead surveillance system (PRESS-BLLs) has been established and operated in Taiwan, Republic of China, since July
1993. A cohort of lead-exposed workers who received a periodic annual health examination at 55 accredited hospital laboratories
was constructed. A total of 9807 separate BLL measurements were reported to the system in 1994. The mean BLL was 15.8 μg/dl
in male workers and 11.6 μg/dl in female workers. The mean BLL of lead-exposed workers was significantly (P<0.05, z-test) higher than that of the general Taiwanese population (8.6 μg/dl for males and 6.7 μg/dl for females). In addition,
the BLLs of 983 (10.0%) workers exceeded the regulatory action level (40 μg/dl for males; 30 μg/dl for females). The workplaces
and homes of 57% of the workers with elevated BLLs were thoroughly investigated to determine the sources of lead contamination.
These actions identified the causes of elevated BLLs and set up strategies to reduce workers’ lead exposure. The establishment
of this occupational lead surveillance system represents a method for monitoring of lead hazards from occupational and environmental
settings to prevent lead poisoning. The information acquired from the system can help in the setting up of a priority of prevention
and the development of control measures. It is also useful for further monitoring of changes in the BLLs of the lead-exposed-worker
cohort. The Health Department of Taiwan can use this information to evaluate the effectiveness of current industrial hygiene
practice. Subjects with elevated BLLs have been medically treated and placed on long-term follow-up for sequelae.
Received: 2 September 1996/Accepted: 29 November 1996 相似文献
70.