全文获取类型
收费全文 | 83291篇 |
免费 | 8206篇 |
国内免费 | 157篇 |
专业分类
耳鼻咽喉 | 1181篇 |
儿科学 | 2500篇 |
妇产科学 | 1801篇 |
基础医学 | 11885篇 |
口腔科学 | 2004篇 |
临床医学 | 10211篇 |
内科学 | 14678篇 |
皮肤病学 | 1312篇 |
神经病学 | 6790篇 |
特种医学 | 2764篇 |
外国民族医学 | 10篇 |
外科学 | 11467篇 |
综合类 | 1662篇 |
一般理论 | 69篇 |
预防医学 | 9533篇 |
眼科学 | 1852篇 |
药学 | 6889篇 |
1篇 | |
中国医学 | 81篇 |
肿瘤学 | 4964篇 |
出版年
2021年 | 1140篇 |
2020年 | 753篇 |
2019年 | 1140篇 |
2018年 | 1415篇 |
2017年 | 1023篇 |
2016年 | 1104篇 |
2015年 | 1253篇 |
2014年 | 1645篇 |
2013年 | 2596篇 |
2012年 | 3503篇 |
2011年 | 3778篇 |
2010年 | 2007篇 |
2009年 | 1930篇 |
2008年 | 3257篇 |
2007年 | 3573篇 |
2006年 | 3442篇 |
2005年 | 3509篇 |
2004年 | 3270篇 |
2003年 | 3057篇 |
2002年 | 2987篇 |
2001年 | 2740篇 |
2000年 | 2848篇 |
1999年 | 2523篇 |
1998年 | 1068篇 |
1997年 | 874篇 |
1996年 | 861篇 |
1995年 | 776篇 |
1994年 | 804篇 |
1993年 | 733篇 |
1992年 | 2094篇 |
1991年 | 2019篇 |
1990年 | 1893篇 |
1989年 | 1855篇 |
1988年 | 1764篇 |
1987年 | 1773篇 |
1986年 | 1679篇 |
1985年 | 1660篇 |
1984年 | 1385篇 |
1983年 | 1254篇 |
1982年 | 837篇 |
1981年 | 714篇 |
1979年 | 1212篇 |
1978年 | 872篇 |
1977年 | 760篇 |
1976年 | 715篇 |
1975年 | 713篇 |
1974年 | 859篇 |
1973年 | 752篇 |
1972年 | 734篇 |
1971年 | 640篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
61.
62.
A. Ian Smith Catherine A. Wallace Lain J. Clarke John W. Funder 《Journal of neuroendocrinology》1989,1(5):357-362
In the sheep, unlike many other species, a significant proportion (>25%) of immunoreactive β-endorphin in the anterior pituitary is post-translationally modified to opioid-inactive, α-N-acetylated forms. In a study to determine the precise molecular nature of α-N-acetylated β-endorphin immunoreactivity, we noted a striking difference in high-performance liquid chromatography profiles of anterior pituitary extracts between sheep killed on the farm, and age-, sex- and strain-matched slaughterhouse animals. These altered patterns of a-N-acetylated β-endorphin processing were reproduced in farm animals by chronic (≤ 4 days) treatment with the synthetic glucocorticoid dexamethasone; in contrast dexamethasone had no effect on a-N-acetylated β-endorphin processing in hypothalamo-pituitary disconnected sheep. These data suggest that (1) the change in processing is a stress response, mediated by prolonged glucocorticoid exposure, (2) this effect is central, rather than a direct effect on the pituitary, and (3) the relative abundance of various peptide sequences in slaughterhouse-derived material may not reflect their abundance under more physiological conditions. 相似文献
63.
G T Keusch J R Cruz B Torun J J Urrutia H Smith A L Goldstein 《Journal of pediatric gastroenterology and nutrition》1987,6(2):265-270
The percentage of peripheral blood lymphocytes forming rosettes with sheep erythrocytes (E-rosettes) was determined in 33 severely malnourished Guatemalan children, and in two groups of clinically well but mildly growth retarded children from the same environment. Mean E-rosettes in the acutely ill patients was lower than the value observed in the mildly malnourished children, although there was considerable overlap between groups. These data differ from previously published studies of severely malnourished children from other parts of the world in that not all patients had decreased values for E-rosettes, in contrast to the uniform depression reported by others. As all patients were clinically similar, the results suggest that there may be specific nutrient defects associated with protein-energy malnutrition that particularly affect immune function. In addition, in vitro incubation of lymphocytes from the acutely malnourished children with the thymic factor, thymosin fraction 5, increased the percentage of E-rosettes in a dose-dependent fashion. These data suggest that immature, thymosin-responsive T cells are present in circulation. It is possible that in vivo thymosin administration may be beneficial for malnourished individuals. 相似文献
64.
Ethylene glycol monomethyl ether (EGME) inhibits rat embryo ornithine decarboxylase (ODC) activity 总被引:1,自引:0,他引:1
The effects of ethylene glycol monomethyl ether (EGME) on reproductive outcome in the rat, and on ornithine decarboxylase (ODC) activity in the rat embryo were evaluated. Dams (n = 8) were treated by gavage on gestation days 6-12 (sperm = day 0) with 0, 25, 50 or 75 mg/kg EGME in 10 ml/kg distilled water. EGME had a dose-dependent effect on reproductive outcome. Gestation length was prolonged, and the number of litters delivered and neonatal body weight were reduced. Whole embryo ODC was measured on gestation days 9, 11, 13 and 15. ODC attained maximum activity in controls on day 11, increasing by more than an order of magnitude above the activity found on day 9. On day 11, a statistically significant dose-dependent inhibition of ODC activity was observed with the maximum dose of EGME inhibiting ODC activity 60 percent. On days 13 and 15, ODC activity declined markedly from peak values, and the dose-dependent inhibition was no longer evident. The study demonstrates a correlation between the inhibition of embryonic ODC activity by EGME and the effect of EGME on reproductive outcome. 相似文献
65.
66.
A A Somogyi F Bochner J A Keal P E Rolan M Smith 《Antimicrobial agents and chemotherapy》1987,31(4):638-639
Fifteen subjects received a single 400-mg oral dose of enoxacin in the fasting state and after carbohydrate and high-fat meals. The carbohydrate meal delayed the time to peak enoxacin concentration in plasma by an average of 0.92 h. The extent of enoxacin absorption was not altered by food. 相似文献
67.
Donna P. Smith 《Children's Health Care》1986,14(3):187-188
Humor has become a popular topic in health care recently. One of the suggested benefits is to help control pain. Although no scientific research to date has validated this effect, there is some theoretical and empirical support for the use of humor especially with children. Methods to implement the uses of humor in a clinical setting are suggested inappropriate uses of humor are also discussed. The need for scientific research is stressed. 相似文献
68.
Roland T. Smith 《American journal of surgery》1943,60(3):438-442
69.
70.
Joseph A. Smith M.D. 《Urologic oncology》2005,23(6):1291