全文获取类型
收费全文 | 1264篇 |
免费 | 104篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 47篇 |
妇产科学 | 34篇 |
基础医学 | 127篇 |
口腔科学 | 13篇 |
临床医学 | 133篇 |
内科学 | 227篇 |
皮肤病学 | 25篇 |
神经病学 | 107篇 |
特种医学 | 115篇 |
外科学 | 174篇 |
综合类 | 77篇 |
预防医学 | 85篇 |
眼科学 | 28篇 |
药学 | 63篇 |
肿瘤学 | 145篇 |
出版年
2022年 | 8篇 |
2021年 | 30篇 |
2020年 | 18篇 |
2019年 | 26篇 |
2018年 | 35篇 |
2017年 | 21篇 |
2016年 | 25篇 |
2015年 | 32篇 |
2014年 | 39篇 |
2013年 | 40篇 |
2012年 | 66篇 |
2011年 | 57篇 |
2010年 | 54篇 |
2009年 | 38篇 |
2008年 | 51篇 |
2007年 | 90篇 |
2006年 | 69篇 |
2005年 | 57篇 |
2004年 | 45篇 |
2003年 | 33篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 29篇 |
1999年 | 26篇 |
1998年 | 33篇 |
1997年 | 37篇 |
1996年 | 35篇 |
1995年 | 24篇 |
1994年 | 16篇 |
1993年 | 26篇 |
1992年 | 22篇 |
1991年 | 26篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 10篇 |
1985年 | 26篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1975年 | 6篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1897年 | 3篇 |
1888年 | 3篇 |
排序方式: 共有1402条查询结果,搜索用时 15 毫秒
1.
2.
3.
Chronic vitamin E treatment prevents defective endothelium-dependent relaxation in diabetic rat aorta 总被引:2,自引:2,他引:0
Summary We examined the effect in rats of 2 months of streptozotocin-induced diabetes mellitus on relaxation and contraction of aortas in vitro. A further diabetic group was treated from time of diabetes induction with a 1% dietary supplement of vitamin E. Diabetes caused a 26.5% deficit (p<0.001) in maximum endothelium-dependent relaxation to acetylcholine in phenylephrine-precontracted aortas. This was 64.3% attenuated (p<0.01) by vitamin E treatment; maximum relaxation was not significantly altered compared to non-diabetic rats. Vitamin E treatment of non-diabetic rats did not significantly affect acetylcholine-induced relaxation. Diabetes or treatment did not significantly alter acetylcholine sensitivity. Endothelium-independent relaxation response to glyceryl trinitrate was not affected by diabetes or vitamin E treatment, indicating that vascular smooth muscle responses to nitric oxide remained unaltered. There was a 35.4% reduction in the maximum contractile response to phenylephrine with diabetes (p<0.05) which was unaffected by vitamin E treatment. The data suggest that the chronic deficit in nitric oxide-mediated endothelium-dependent relaxation in diabetes depends largely upon excess activity of reactive oxygen species. Treatment with vitamin E to increase free radical scavenging specifically protected vascular endothelium although it had no effect on deficits in vascular smooth muscle contractile responses.Abbreviations NO
Nitric oxide
- ARI
aldose reductase inhibitor
- ACH
acetylcholine
- GTN
glyceryl trinitrate
- GSH
reduced form of glutathione
- EC50
effective concentration for 50% of the maximal response 相似文献
4.
A non-destructive technique to determine the time since last purification of weapons grade plutonium based on the 241Pu decay series has been developed and demonstrated to provide results that are consistent with our historical and process knowledge. This method is based on the use of the Bateman equations and the decay chain 241Pu-->237U & 241Am-->237Np-->233Pa. Secular equilibrium is assumed between the (2.1 x 10(6) year) 237Np and the (27 day) 233Pa. The proposed method is dependent upon the efficiency of the plutonium separation process but makes no assumption about the relative abundance of 241Pu in 239Pu. Even though the technique was developed for weapons grade plutonium, it is expected to apply to almost any material that contains plutonium. 相似文献
5.
6.
H S Watson E O Singh M R Hermans K S Coffield G T Keegan 《The Journal of urology》1992,147(3):689-691
We report a case of eosinophilic cystitis that was responsive to prednisone but that recurred when the drug was withdrawn. The cause of eosinophilic cystitis remains an enigma but it probably represents a form of allergy. Investigation of etiology and therapeutic options are discussed. 相似文献
7.
While technologic problems in critical care have become highly refined with precise solutions, ethical problems and solutions have remained fairly primitive. A useful distinction between technology and techniques is made with individual technologies being the parts that make up the therapeutic techniques as a whole. The phenomena of “technical convergence” is discussed wherein we may control each part of the system, but the system itself may be out of control. This is explained in terms of the logical fallacy of composition, noting that a whole may not necessarily have the same characteristics of its parts. Resolution of some of the ethical problems in critical care is suggested through a reexamination of the physician-patient relationship. It is noted that the relationship needs to be personal-technologic rather than sociotechnologic in nature, with the former focusing solely on the best interest of the individual patient and the latter focusing more on the broader concerns of society in the allocation of limited resources. The detrimental effects for the physician as well as the patient of the shift toward the sociotechnologic relationship is explored, especially the dehumanization of the physician. A call for a reaffirmation of the traditional professional model of medicine emphasizing the best interest of patients as opposed to the more popular business model emphasizing materialism and efficiency is given. 相似文献
8.
Relative carriage rates of nuclear dehydrogenating clostridia in two populations of different colorectal cancer risk
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Carriage of nuclear dehydrogenating clostridia has been associated with colon cancer and implicated in its aetiology. This study has compared the carriage of these organisms in a British population at high risk for the development of colon cancer with a low risk Nigerian population. Clostridia were found in all of the stools from both populations. Nuclear dehydrogenating clostridia were only found in the stools of the British subjects (32%). These results support the suggestion that the carriage rate of nuclear dehydrogenating clostridia in a population is related to the risk of colon cancer. 相似文献
9.
Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system 总被引:8,自引:0,他引:8
Hwu YM; Lee RK; Chen CP; Su JT; Chen YW; Lin SP 《Human reproduction (Oxford, England)》1998,13(7):1916-1921
Recently, in-vitro maturation (IVM) of immature human oocytes recovered
from non-stimulated follicles has been applied in the treatment of
infertility. However, in previous reports, very few embryos cultured in
conventional medium have reached the expanded blastocyst stage following
in-vitro maturation and fertilization (IVM/IVF). The objective of this
study was to investigate whether the developmental competence of human
embryos following IVM/IVF could be enhanced by the use of a human ampullary
cell co-culture system. Immature human oocytes were aspirated from small
follicles at Caesarean section and then cultured in medium containing human
menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes
were randomly cultured either in conventional culture medium alone or in
the co-culture system. Of 48 embryos cultured in conventional medium alone,
all arrested at the 2-16- cell stage on day 3 after insemination. Of 46
embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at
the 2-16-cell stage. Six embryos (13%) developed to the morula stage.
Fourteen embryos (30.4%) developed to expanded blastocysts and two
blastocysts were hatching on day 7 after insemination. We conclude that
co-culture significantly enhances the development of blastocysts in embryos
resulting from IVM/IVF.
相似文献
10.
Long-term preservation of cortically dependent visual function in RCS rats by transplantation. 总被引:8,自引:0,他引:8
P J Coffey S Girman S M Wang L Hetherington D J Keegan P Adamson J Greenwood R D Lund 《Nature neuroscience》2002,5(1):53-56
Cell transplantation is one way of limiting the progress of retinal degeneration in animal models of blinding diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Here we transplanted a human retinal pigment epithelial (RPE) cell line into the subretinal space of one such model, the Royal College of Surgeons (RCS) rat, and showed, using head tracking to moving stripes and pattern discrimination in conjunction with single-unit cortical physiology, that cortically mediated vision can be preserved with this treatment. 相似文献