全文获取类型
收费全文 | 2365篇 |
免费 | 186篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 126篇 |
妇产科学 | 26篇 |
基础医学 | 274篇 |
口腔科学 | 40篇 |
临床医学 | 293篇 |
内科学 | 385篇 |
皮肤病学 | 50篇 |
神经病学 | 173篇 |
特种医学 | 409篇 |
外科学 | 264篇 |
综合类 | 41篇 |
一般理论 | 2篇 |
预防医学 | 191篇 |
眼科学 | 34篇 |
药学 | 112篇 |
中国医学 | 1篇 |
肿瘤学 | 127篇 |
出版年
2021年 | 23篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 14篇 |
2016年 | 25篇 |
2015年 | 36篇 |
2014年 | 39篇 |
2013年 | 59篇 |
2012年 | 70篇 |
2011年 | 47篇 |
2010年 | 62篇 |
2009年 | 52篇 |
2008年 | 65篇 |
2007年 | 93篇 |
2006年 | 90篇 |
2005年 | 78篇 |
2004年 | 89篇 |
2003年 | 66篇 |
2002年 | 66篇 |
2001年 | 54篇 |
2000年 | 41篇 |
1999年 | 66篇 |
1998年 | 114篇 |
1997年 | 86篇 |
1996年 | 97篇 |
1995年 | 76篇 |
1994年 | 72篇 |
1993年 | 74篇 |
1992年 | 50篇 |
1991年 | 41篇 |
1990年 | 35篇 |
1989年 | 63篇 |
1988年 | 56篇 |
1987年 | 63篇 |
1986年 | 60篇 |
1985年 | 54篇 |
1984年 | 49篇 |
1983年 | 41篇 |
1982年 | 35篇 |
1981年 | 39篇 |
1980年 | 37篇 |
1979年 | 14篇 |
1978年 | 30篇 |
1977年 | 28篇 |
1976年 | 30篇 |
1975年 | 19篇 |
1974年 | 15篇 |
1973年 | 11篇 |
1970年 | 9篇 |
排序方式: 共有2562条查询结果,搜索用时 15 毫秒
1.
Needle-localized breast biopsy: why do we fail? 总被引:10,自引:0,他引:10
2.
D G Laing 《Physiology & behavior》1986,37(1):163-170
The duration that a single odor needs to be sniffed for identification was determined for 18 humans. A hot wire anemometer and an oscilloscope were used to monitor the duration, volume and inhalation rate of sniffs. In Experiment 1 subjects used 1, 3 or 5 natural sniffs, or an unlimited number of natural sniffs to sample seven dissimilar single odors of moderate perceived intensity, and demonstrated that each odor could be identified with a single sniff. In Experiment 2 subjects demonstrated that each of the odors could be identified with the shortest sniff (0.42 sec) they could physically achieve. In Experiment 3 tests with two of the odorants at several concentrations showed that sniff duration influences identification over a narrow range of concentrations that is just above the recognition threshold. These results together with earlier data that described the optimum conditions for the detection of an odor and the perception of odor intensity, provide information that is necessary for the development of a standard olfactometer and standard methods for human olfactory measurements. 相似文献
3.
4.
Ketai LH; Williamson MR; Telepak RJ; Levy H; Koster FT; Nolte KB; Allen SE 《Radiology》1994,191(3):665
5.
Abnormalities in glucose metabolism are thought to be among the main causes of cataract formation. The authors have made noninvasive biochemical measurements of the lens that provide information concerning glucose metabolism in the lens epithelium. The autofluorescence of reduced pyridine nucleotides (PN) and oxidized flavoproteins (Fp) within the rabbit lens were noninvasively measured as a function of depth using redox fluorometry. The peak of the autofluorescence at 440 nm (excited at 360 nm) and 540 nm (excited at 460 nm) were determined at the lens epithelium. When 8 mM sodium pentobarbital, a known inhibitor of mitochondrial respiration, was applied to the lens, the autofluorescence peak at 440 nm increased and that at 540 nm decreased. The 440 nm autofluorescence is thought to be from reduced pyridine nucleotides, whereas the 540 nm autofluorescence is from the oxidized flavoprotein. Blocking lens respiration with pentobarbital caused an increase in the PN/Fp ratio by a factor of 3 within 3.5 hr after pentobarbital application. 相似文献
6.
7.
8.
荧光原位杂交技术分析人结肠菌群方法研究 总被引:2,自引:0,他引:2
建立荧光原位杂交技术分析人体内结肠菌群的方法。取受试者新鲜粪便 ,选用 5种特异性的 16SrRNA寡核苷酸探针 ,检测粪便样本收集后的保存时间、温度 ,离心条件及样本固定液存放时间对杂交计数结果的影响。结果建立最佳实验条件为 :粪便样本收集后应尽快在 4℃下保存 ,放置时间不要超过 12小时即作处理 ;样本的适宜离心条件为 70 0g 2分钟 ;样本用多聚甲醛固定后在 - 80℃下存放时间不要超过 5个月。该方法具有较好的稳定性 ,可以有效地检出个体之间结肠菌群的差异。 相似文献
9.
R. Minkoff V. R. Rundus S. B. Parker E. L. Hertzberg J. G. Laing E. C. Beyer 《Anatomy and embryology》1994,190(3):231-241
The spatial and temporal expression of three closely related members of the connexin family of gap junction proteins (connexin42, Cx42; connexin43, Cx43; and connexin45, Cx45) was evaluated during bone formation in the mandibular process of the chick embryo. Mandibles of chick embryos from Hamburger and Hamilton stage 25 (approximately 5 days) through 19 days of development were dissected, serially sectioned and processed for immunocytochemical localization, employing site-specific anti-connexin antibodies. Our data revealed that (1) Cx43 was present throughout mandibular bone formation; (2) although it appeared to be associated with all bone cell types, Cx43 was concentrated in mesenchymal cells during the earliest stages in the osteogenic lineage; (3) most importantly, the localization of Cx43 at sites of bone formation appeared to precede the overt expression of the osteogenic phenotype; (4) by contrast, Cx45 was more restricted, spatially and temporally, in its distribution; (5) Cx42 expression was not detected in osteogenic tissue during mandibular bone formation. From all of the data obtained, Cx45 appeared to be associated with stages of bone formation characterized by the elaboration of matrix and the progressive expression of the differentiated osteogenic phenotype. Cx43 appeared to be associated with condensation of mesenchyme and the earliest stages of osteogenesis. Because of these associations, we propose that connexin expression may be necessary for the initiation of bone formation and the full expression of the osteogenic phenotype. 相似文献
10.