全文获取类型
收费全文 | 4013篇 |
免费 | 402篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 136篇 |
妇产科学 | 78篇 |
基础医学 | 673篇 |
口腔科学 | 28篇 |
临床医学 | 504篇 |
内科学 | 714篇 |
皮肤病学 | 43篇 |
神经病学 | 518篇 |
特种医学 | 74篇 |
外科学 | 352篇 |
综合类 | 44篇 |
一般理论 | 10篇 |
预防医学 | 456篇 |
眼科学 | 97篇 |
药学 | 333篇 |
中国医学 | 1篇 |
肿瘤学 | 333篇 |
出版年
2023年 | 22篇 |
2022年 | 51篇 |
2021年 | 99篇 |
2020年 | 49篇 |
2019年 | 78篇 |
2018年 | 91篇 |
2017年 | 83篇 |
2016年 | 85篇 |
2015年 | 95篇 |
2014年 | 123篇 |
2013年 | 153篇 |
2012年 | 283篇 |
2011年 | 275篇 |
2010年 | 130篇 |
2009年 | 123篇 |
2008年 | 248篇 |
2007年 | 248篇 |
2006年 | 231篇 |
2005年 | 229篇 |
2004年 | 223篇 |
2003年 | 199篇 |
2002年 | 157篇 |
2001年 | 88篇 |
2000年 | 88篇 |
1999年 | 86篇 |
1998年 | 43篇 |
1997年 | 34篇 |
1996年 | 38篇 |
1995年 | 31篇 |
1994年 | 43篇 |
1993年 | 24篇 |
1992年 | 57篇 |
1991年 | 43篇 |
1990年 | 47篇 |
1989年 | 41篇 |
1988年 | 46篇 |
1987年 | 40篇 |
1986年 | 32篇 |
1985年 | 30篇 |
1984年 | 29篇 |
1983年 | 25篇 |
1981年 | 18篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 21篇 |
1975年 | 20篇 |
1974年 | 20篇 |
1968年 | 16篇 |
1967年 | 15篇 |
排序方式: 共有4425条查询结果,搜索用时 15 毫秒
1.
2.
3.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications. 相似文献
4.
Andrew E. Springer Kayan Lewis Steven H. Kelder Maria E. Fernandez Cristina S. Barroso Deanna M. Hoelscher 《Journal of immigrant and minority health / Center for Minority Public Health》2010,12(5):769-780
Research on physical activity (PA) by level of acculturation in Hispanic children is limited and findings have been mixed.
We examined PA participation by primary language used with parents in a representative sample of 4th, 8th, and 11th grade
Texas public school students. Mixed-effects regression models were conducted using cross-sectional data from the 2004–2005
School Physical Activity and Nutrition Study (n = 22,049). Self-reported PA was compared among three language-ethnic groups: Spanish-Hispanic (SH) (referent); English-Hispanic
(EH); and English-Other (EO). EH and/or EO girls were generally between 1.25 and 2.58 [OR] times more likely to participate in PA across grade levels,
with the largest differences found for school sports in 8th grade girls. EH and EO 8th grade boys were 1.71 (CI: 1.40, 2.10)
and 2.06 (CI: 1.68, 2.51) times, respectively, more likely to participate in school sports. Findings indicate important disparities
in Spanish-speaking Hispanic children’s PA participation. 相似文献
5.
6.
7.
The proliferative T-lymphocyte response to streptokinase 总被引:1,自引:0,他引:1
Purified streptokinase was found to initiate a proliferative T-lymphocyte response. The response was characterized by dose-response and kinetics investigations. Streptokinase did not initiate any response when tested on T lymphocytes from newborns, thus indicating that the proliferative T-lymphocyte response to streptokinase in vitro is an antigen stimulated activation of T lymphocytes from individuals previously sensitized in vivo. Of healthy individuals, 40% (16 out of 40 tested) showed a significant proliferative response to streptokinase. Methylprednisolone, cyclosporin A, theophyllamine and verapamil all inhibited the streptokinase-stimulated proliferative T-lymphocyte responses in a dose-dependent manner. 相似文献
8.
Gene delivery systems are designed to control the location of administered therapeutic genes within a patient's body. Successful in vivo gene transfer may require (i) the condensation of plasmid and its protection from nuclease degradation, (ii) cellular interaction and internalization of condensed plasmid, (iii) escape of plasmid from endosomes (if endocytosis is involved), and (iv) plasmid entry into cell nuclei. Expression plasmids encoding a therapeutic protein can be, for instance, complexed with cationic liposomes or micelles in order to achieve effective in vivo gene transfer. A thorough knowledge of pharmaceutics and drug delivery, bio-engineering, as well as cell and molecular biology is required to design optimal systems for gene therapy. This mini-review provides a critical discussion on cationic lipid-based gene delivery systems and their possible uses as pharmaceuticals. 相似文献
9.
10.
The transport of L- and D-lactate into rat pancreatic islets and HIT-T15 insulinoma cells was studied by measuring uptake of 14C-labelled substrate at room temperature and by following changes in intracellular pH (pHi) in islets and HIT-T15 cells loaded with 2',7'-bis(carboxyethyl)-5'(6')-carboxyfluorescein (BCECF). Uptake of L-lactate into HIT-T15 cells was rapid, reaching equilibrium after 5 min with an apparent Km value of 4.8 mM. Transport was markedly inhibited by alpha-cyano-4-hydroxycinnamate, alpha-fluorocinnamate, quercetin and p-chloromercuribenzenesulphonate (pCMBS), and was enhanced in citrate medium. Uptake of D-lactate was less rapid, apparent equilibrium not being reached within 10 min. In contrast to HIT-T15 cells, rat pancreatic islets showed greatly reduced rates of transport of L- and D-lactate together with a correspondingly lower degree of inhibition by alpha-cyano-4-hydroxycinnamate. The addition of L- or D-lactate to HIT-T15 cells, but not dispersed islet cells, resulted in a marked and rapid intracellular acidification followed by a gradual recovery. In both HIT-T15 cells and isolated islets, the rates of transport of both L- and D-lactate in the presence of alpha-cyano-4-hydroxycinnamate were significantly greater in a depolarising K+ medium compared to the normal Na+ medium. These observations suggest that native rat islet cells have considerably reduced activity of the lactate-/H+ transport system compared to HIT-T15 insulinoma cells. There is evidence in both cell types of an additional electrogenic pathway for lactate which might play a role in coupling lactate efflux to beta-cell depolarisation. 相似文献