全文获取类型
收费全文 | 1795篇 |
免费 | 168篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 39篇 |
妇产科学 | 28篇 |
基础医学 | 241篇 |
口腔科学 | 33篇 |
临床医学 | 215篇 |
内科学 | 361篇 |
皮肤病学 | 31篇 |
神经病学 | 58篇 |
特种医学 | 179篇 |
外科学 | 232篇 |
综合类 | 92篇 |
一般理论 | 3篇 |
预防医学 | 152篇 |
眼科学 | 23篇 |
药学 | 91篇 |
1篇 | |
中国医学 | 19篇 |
肿瘤学 | 160篇 |
出版年
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 34篇 |
2019年 | 41篇 |
2018年 | 46篇 |
2017年 | 21篇 |
2016年 | 26篇 |
2015年 | 52篇 |
2014年 | 41篇 |
2013年 | 60篇 |
2012年 | 68篇 |
2011年 | 65篇 |
2010年 | 61篇 |
2009年 | 58篇 |
2008年 | 76篇 |
2007年 | 86篇 |
2006年 | 46篇 |
2005年 | 79篇 |
2004年 | 55篇 |
2003年 | 73篇 |
2002年 | 53篇 |
2001年 | 57篇 |
2000年 | 42篇 |
1999年 | 45篇 |
1998年 | 45篇 |
1997年 | 31篇 |
1996年 | 45篇 |
1995年 | 38篇 |
1994年 | 33篇 |
1993年 | 29篇 |
1992年 | 19篇 |
1991年 | 30篇 |
1990年 | 21篇 |
1989年 | 47篇 |
1988年 | 37篇 |
1987年 | 26篇 |
1986年 | 28篇 |
1985年 | 31篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 17篇 |
1973年 | 15篇 |
1972年 | 14篇 |
1970年 | 13篇 |
排序方式: 共有1968条查询结果,搜索用时 15 毫秒
1.
Chemical-shift imaging: a hybrid approach 总被引:1,自引:0,他引:1
The hybrid technique of projection-reconstruction echo-planar (PREP) imaging for obtaining chemical-shift images is demonstrated experimentally using a fluorine sample. The technique which is a variation on echo-planar imaging (EPI) relies on a multipass procedure. It is nevertheless quite efficient and consequently chemical-shift images may be produced in a few minutes. The method produces images in 64 chemical-shift regions, each region mapped spatially by 64 X 64 pixels. The imaging time was just over 4 min. These 64 chemical-shifted images can be straightforwardly added together to form an undistorted image of the complete object. In addition the chemical-shift spectrum can be extracted and the various chemical-shift images can be unambiguously assigned to the spectral peaks. 相似文献
2.
AMPK在妊娠期糖尿病发病机制中的作用 总被引:1,自引:0,他引:1
腺苷酸活化蛋白激酶是一种重要的蛋白激酶,主要作用是协调代谢和能量平衡.腺苷酸活化蛋白激酶被激活后,在增加骨骼肌对葡萄糖摄取、增强胰岛素敏感性、增加脂肪酸氧化以及调节基因转录等方面发挥重要作用.已经证实脂联素有调节糖脂代谢的作用,但其作用机制尚不十分清楚,很可能是通过腺苷酸活化蛋白激酶介导,对脂联素信号转导通路的研究将成为进一步理解脂联素作用的关键所在.而脂联素又是妊娠期糖尿病的预测因子,所以腺苷酸活化蛋白激酶逐渐成为对妊娠期糖尿病研究中的焦点. 相似文献
3.
4.
5.
Trypanosome variant surface glycoproteins are recognized by self-reactive antibodies in uninfected hosts. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The variant surface glycoproteins (VSGs) of African trypanosomes form a dense surface coat on the bloodstream parasites. VSGs are immunodominant antigens that stimulate a rapid antibody response in trypanosome-infected individuals. In the present study, we examined VSG-specific antibodies present not only in sera from infected individuals but also in sera from individuals that had never been exposed to trypanosomes. Native antibodies against different VSGs were detected in sera from uninfected mice, bovines, and humans; the antibodies were revealed to be exclusively directed against variable determinants of the antigens. Further experimentation demonstrated that such native antibodies immunoreact with cellular components of mice and thus are most likely produced by the self-reactive B-cell compartment of the murine immune system. 相似文献
6.
Remotely inserted venous occlusion catheters for the control of venous haemorrhage. 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Annals of the Royal College of Surgeons of England》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S. R. Smith A. O. Mansfield J. P. Bradley 《Annals of the Royal College of Surgeons of England》1988,70(3):161-162
This paper describes the use of venous occlusion catheters inserted via the long saphenous vein or its tribularies for control of major retroperitoneal venous haemorrhage. The technique has been applied successfully in 10 cases of trauma and aortocaval fistula. Exposure and insertion are simple and quick and a measure of control is obtained before exposure of the injury which can then be completely repaired before deflation of the balloon and withdrawal of the catheter. 相似文献
7.
Kazumasa Fujitani Jaffer A. Ajani Christopher H. Crane Barry W. Feig Peter W. Pisters Nora Janjan Garrett L. Walsh Stephen G. Swisher Ara A. Vaporciyan David Rice Angela Welch Jackie Baker Josephine Faust Paul F. Mansfield MD 《Annals of surgical oncology》2007,14(4):1305-1311
Background Significant tumor downstaging has been achieved in patients with localized gastric or gastroesophageal adenocarcinoma by induction
chemotherapy and preoperative chemoradiotherapy (CTX–CTXRT). However, the influence of CTX–CTXRT on operative morbidity and
mortality has not yet been clarified. The aim of the present study was to document the frequency and nature of morbidity and
mortality after surgery combined with CTX–CTXRT, and identify factors predictive of postoperative complications in patients
with localized gastric or gastroesophageal adenocarcinoma.
Methods A prospectively collected database on 71 consecutive patients who underwent CTX–CTXRT at M.D. Anderson Cancer Center between
January 1997 and August 2004 was reviewed. Postoperative morbidity and mortality were investigated, and risk factors for overall
complications were identified by multivariate logistic regression analysis.
Results Overall morbidity and mortality rates were 38.0% (27 patients) and 2.8% (2 patients), respectively. Age greater than 60 years
[relative risk 11.3 (95% confidence interval 2.50–50.6)] and body mass index (BMI) of 26 kg/m2 or above [relative risk 4.08 (95% confidence interval 1.08–15.4)] were significant risk factors for overall complications.
Conclusions CTX–CTXRT can be performed safely with an acceptable operative morbidity and a low operative mortality rate in patients with
gastric or gastroesophageal cancer, with careful consideration of added risk associated with age and obesity. 相似文献
8.
Rajabi-Siahboomi Ali R. Bowtell Richard W. Mansfield Peter Davies Martyn C. Melia Colin D. 《Pharmaceutical research》1996,13(3):376-380
Purpose. The purpose of this study was to characterise the water mobility in the gel layer of hydrating HPMC tablets. Water mobility in the gel layer of different HPMCs was studied.
Methods. NMR imaging, a non-invasive technique, has been used to measure the spatial distribution of self-diffusion coefficient (SDC) and T2 relaxation times across the gel layer.
Results. It has been shown that there is a water mobility gradient across the gel layer of HPMC tablets. Although SDC and T2 relaxation times in the outer parts of the gel layer approached that of free water, in the inner parts they decreased progressively. Water mobility and SDC in the gel layer of different HPMCs appeared to vary with degree of substitution of the polymer and the lowest values were obtained across the gel layer of K4M tablets.
Conclusions. Water mobility varies across the gel layer of hydrating HPMC tablets and it is dependent on the degree of substitution of the polymer. 相似文献
9.
10.
Richard W. Bowtell Andrew Peters Jonathan C. Sharp Peter Mansfield Edward W. Hsu Nanci Aiken Anthony Horsman Stephen J. Blackband 《Magnetic resonance in medicine》1995,33(6):790-794
NMR microimages of single neural cells were acquired at 500 MHz using a conventional spin echo pulse sequence and a line-narrowing sequence that eliminates susceptibility effects. The data show that any contribution to the measured T2 relaxation rate arising from diffusion in local field inhomogeneities using spin echo sequences at high fields and high spatial resolution is relatively small. We conclude that the measured T2 difference between the nucleus and cytoplasm in these cells represents primarily a true T2 relaxation effect arising from the interactions of water with macromolecules in the two compartments and does not result from microsusceptibility differences. These observations have implications regarding water compartmentation in single cells and the interpretation of the MR characteristics of tissues in vivo. 相似文献