全文获取类型
收费全文 | 61742篇 |
免费 | 4754篇 |
国内免费 | 533篇 |
专业分类
耳鼻咽喉 | 1009篇 |
儿科学 | 1256篇 |
妇产科学 | 1147篇 |
基础医学 | 9690篇 |
口腔科学 | 964篇 |
临床医学 | 5626篇 |
内科学 | 12798篇 |
皮肤病学 | 1876篇 |
神经病学 | 5356篇 |
特种医学 | 3295篇 |
外科学 | 7330篇 |
综合类 | 642篇 |
现状与发展 | 1篇 |
一般理论 | 26篇 |
预防医学 | 4049篇 |
眼科学 | 1729篇 |
药学 | 5165篇 |
中国医学 | 502篇 |
肿瘤学 | 4568篇 |
出版年
2023年 | 369篇 |
2022年 | 1003篇 |
2021年 | 1688篇 |
2020年 | 877篇 |
2019年 | 1370篇 |
2018年 | 1603篇 |
2017年 | 1235篇 |
2016年 | 1851篇 |
2015年 | 2381篇 |
2014年 | 2738篇 |
2013年 | 3353篇 |
2012年 | 4723篇 |
2011年 | 4622篇 |
2010年 | 2790篇 |
2009年 | 2339篇 |
2008年 | 3358篇 |
2007年 | 3363篇 |
2006年 | 2979篇 |
2005年 | 2877篇 |
2004年 | 2479篇 |
2003年 | 2198篇 |
2002年 | 2013篇 |
2001年 | 1111篇 |
2000年 | 1060篇 |
1999年 | 925篇 |
1998年 | 478篇 |
1997年 | 398篇 |
1996年 | 338篇 |
1995年 | 344篇 |
1994年 | 285篇 |
1993年 | 313篇 |
1992年 | 634篇 |
1991年 | 663篇 |
1990年 | 574篇 |
1989年 | 624篇 |
1988年 | 608篇 |
1987年 | 609篇 |
1986年 | 514篇 |
1985年 | 528篇 |
1984年 | 439篇 |
1983年 | 363篇 |
1982年 | 286篇 |
1981年 | 260篇 |
1980年 | 237篇 |
1979年 | 319篇 |
1978年 | 287篇 |
1977年 | 212篇 |
1974年 | 217篇 |
1973年 | 239篇 |
1972年 | 193篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BACKGROUND. A health risk appraisal (HRA) is a tool for health promotion. Conversational microcomputer-based HRAs may be more cost effective than other HRA formats. The acceptability of conversational HRAs, however, has not been demonstrated for older adults. METHODS. We studied the acceptability of a conversational microcomputer-based HRA in a sample of 247 adults at the Minnesota State Fair and the Senior Options Exposition. All users were offered the appraisal via mouse or keyboard interface. Acceptability was measured in terms of user-reported helpfulness, intent to change, time of use, and willingness to view HRA health recommendations. Data on completion time and willingness to view HRA recommendations were collected for Senior Exposition users only. Regression analyses were used to examine the combined impact of interface (mouse or keyboard), location (State Fair or Senior Exposition), age, and sex on user acceptability. Results. Interface and location had no effect on helpfulness or change ratings. Older users rated the appraisal more helpful (P less than .007). Both older and female users reported more intent to change behavior (P = .016, both). Time to use the appraisal was related to interface, age, and sex. Mouse users (P less than .0001), older users (P less than .0001) and female users (P less than .05) took significantly longer to use the appraisal. Significantly more mouse users declined to see recommendations (P less than .02). CONCLUSIONS. Older users can derive as much or more value from conversational health risk appraisals as younger users; however, a mouse interface may be less effective for this age group. 相似文献
52.
53.
This study has shown that the retinae of Prototherian (egg-laying) mammals possess two neuronal types that are present in non-mammalian retinae, but absent or morphologically different in the retinae of Eutherian (placental) mammals. First, endogenous serotonin-like immunoreactivity has been localized in a population of presumptive amacrine cells in the platypus retina, the first such report in a mammalian retina. Second, the protein kinase C-immunoreactive (PKC-IR) bipolar cells in the echidna retina appear similar to the PKC-IR bipolars in the chicken retina, in that their dendrites give rise to a Landolt's club and their axons are multistratified. By contrast, the PKC-IR rod bipolar cells in the rabbit and in the brushtail possum, a Metatherian (marsupial) mammal, have no Landolt's clubs and their axons form terminal lobes in the innermost stratum of the inner plexiform layer. 相似文献
54.
55.
56.
Jin Woo Kim M.D. Ho Shik Kim M.D. In Kyung Kim M.D. Mee Ran Kim M.D. Eun Young Cho B.S. Heung Kee Kim M.D. Joon Mo Lee M.D. Sung Eun Namkoong M.D. 《Gynecologic oncology》1998,69(3):230-236
Transforming growth factor-β1 (TGF-β1) is known to be a potent growth inhibitor for many cell types, including most epithelial cells. In skin keratinocytes, TGF-β1 has been shown to inhibit growth and to rapidly reduce c-mycexpression. However, the molecular mechanism of TGF-β1 action on cell growth of cervical carcinoma has not yet been elucidated. We thus assessed the effect of TGF-β1 on the growth of cervical carcinoma cell lines. Two cervical squamous carcinoma cell lines, CUMC-3 and CUMC-6, were incubated with varying concentrations of TGF-β1, and growth inhibition was evaluated with tetrazolium-based colorimetric assay. After culture in TGF-β1 for 24 h, inhibition of growth was detected in a dose-dependent manner at concentrations of 0.1–10 ng/ml in both cell lines. This effect of TGF-β1 on cultured carcinoma cells was associated with apoptotic process including oligonucleosomal ladder DNA and apoptotic body formations. Northern blot analysis revealed c-mycmRNA expression was suppressed by 10 ng/ml of TGF-β1 following 3 h of treatment in both cell lines. Western blot analysis showed that the level of p27Kip1protein was increased after TGF-β1 treatment in both cell lines. These results suggest that the mechanisms by which TGF-β1 inhibits the growth of cervical carcinoma are complex and may include effects on down-regulation of c-mycgene, and overexpression of p27Kip1protein. 相似文献
57.
58.
59.
60.