全文获取类型
收费全文 | 1869篇 |
免费 | 113篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 92篇 |
妇产科学 | 18篇 |
基础医学 | 203篇 |
口腔科学 | 40篇 |
临床医学 | 208篇 |
内科学 | 503篇 |
皮肤病学 | 30篇 |
神经病学 | 70篇 |
特种医学 | 253篇 |
外科学 | 142篇 |
综合类 | 64篇 |
预防医学 | 104篇 |
眼科学 | 20篇 |
药学 | 62篇 |
中国医学 | 9篇 |
肿瘤学 | 161篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 22篇 |
2018年 | 30篇 |
2017年 | 17篇 |
2016年 | 19篇 |
2015年 | 38篇 |
2014年 | 61篇 |
2013年 | 77篇 |
2012年 | 76篇 |
2011年 | 66篇 |
2010年 | 68篇 |
2009年 | 94篇 |
2008年 | 90篇 |
2007年 | 109篇 |
2006年 | 65篇 |
2005年 | 63篇 |
2004年 | 53篇 |
2003年 | 51篇 |
2002年 | 37篇 |
2001年 | 27篇 |
2000年 | 41篇 |
1999年 | 36篇 |
1998年 | 85篇 |
1997年 | 55篇 |
1996年 | 71篇 |
1995年 | 47篇 |
1994年 | 53篇 |
1993年 | 47篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 35篇 |
1989年 | 46篇 |
1988年 | 36篇 |
1987年 | 40篇 |
1986年 | 35篇 |
1985年 | 25篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 17篇 |
1981年 | 24篇 |
1980年 | 17篇 |
1979年 | 18篇 |
1978年 | 10篇 |
1977年 | 19篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1973年 | 3篇 |
排序方式: 共有1991条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
Magnetic resonance (MR) imaging has been used in the temporomandibular joint (TMJ) primarily to define the disk position. This report examines altered morphology and signal intensity characteristics of the TMJ disk as they relate to the severity of internal derangement. Two hundred sixteen joints in 133 patients with a history of such derangement. were imaged with MR. Disk position, signal intensity, morphology, and the presence of osteoarthritis were determined for each joint. The normal disk was not anteriorly displaced and had a normal "bow-tie" shape. A grade 1 disk was anteriorly displaced and had a normal shape; a grade 2 disk was anteriorly displaced and had an abnormal shape. Forty (19%) joints were considered normal; none of these exhibited osteoarthritis. One hundred thirty-nine (64%) joints were grade 1; osteoarthritis was found in 17%. Thirty-seven (17%) were grade 2; osteoarthritis was found in 95%. All forty normal joints had high or intermediate signal intensity in the disk. Osteoarthritic joints had a higher percentage of disks with diminished intensity (P less than .0001). Severe or untreated osteoarthritis is known to be a complication of TMJ internal derangements; hence this grading system seems to correlate with the severity of internal derangement. 相似文献
15.
16.
A study of the degree of progesterone support required for the maintenance
of various stages of pregnancy was undertaken in mice. Mated females were
ovariectomized at various stages of pregnancy and progesterone and
oestradiol support provided by s.c. Silastic implants with known release
characteristics. In the earliest stages of pregnancy (days 1-5), very low
concentrations of progesterone (<25% of normal physiological values)
were sufficient to maintain pre-implantation stages and allow implantation.
In the immediate post-implantation period (days 5-9), the development of
implantation sites and decidualization required considerably higher
progesterone support. In mid-pregnancy (days 11-14), progesterone alone
could not maintain pregnancy unless present in very high amounts; however,
the presence of oestradiol during this period lowered the progesterone
requirements to well within the physiological range. This effect of
oestradiol started on day 11 but required the level of oestradiol support
to be kept within strictly defined limits, with high concentrations
inducing abortion. Progesterone alone was able to maintain pregnancy from
day 15. These results indicate that the minimal progesterone support
required for pregnancy in mice varies considerably at different stages of
pregnancy and is at least partly modulated by oestradiol.
相似文献
17.
Petrini P Tanzi MC Visai L Casolini F Speziale P 《Journal of biomaterials science. Polymer edition》2000,11(4):353-365
In order to obtain heparin-binding polyurethanes, tertiary amino-groups have been introduced in the polymer backbone by attributing a key-role to the chain extender, i.e. substituting butanediol, commonly used in polyurethane synthesis, with a tailor-made diamino-diamide-diol. In this work a poly(ether-urethane-aminoamide) (PEU/PIME/al) was obtained with poly(oxytetramethylene) glycol 2000, 1,6-hexamethylene-diisocyanate and the new chain extender, in the molar ratio 1:2:1. The heparin binding capacity of PEU/PIME/al was evaluated with 125I labelled heparin, using for comparison the analogous polymer obtained with a diamide-diol (i.e. the poly(ether-urethane-amide) PEU/PIBLO/al), and two commercially available biomedical polyurethanes (Pellethane 2363 and Corethane). pH and ionic strength dependence of the heparin uptake were investigated by treating all the polyurethanes with solutions of 125I heparin into buffers from pH 4 to 9 or NaCl molarity from 0.0 to 1.0. The stability of the interaction with bound heparin was investigated by sequential washing treatments (PBS, 1 N NaOH, 2% SDS solution), then analysing the residual radioactivity on the materials. Results indicated that the heparin binding of PEU/PIME/al is significantly higher and more stable than that of the other polyurethanes, with a time-dependent kinetic. The interaction with heparin appears to be prevalently ionic, with the contribution of other electrostatic and hydrophobic interactions. Activated partial thromboplastin time (APTT), performed on human plasma with polyurethane-coated, heparinized test tubes, indicated that bound heparin maintains its biological activity after the adsorption. 相似文献
18.
19.
Elastin point mutations cause an obstructive vascular disease, supravalvular aortic stenosis 总被引:7,自引:2,他引:7
Li DY; Toland AE; Boak BB; Atkinson DL; Ensing GJ; Morris CA; Keating MT 《Human molecular genetics》1997,6(7):1021-1028
Supravalvular aortic stenosis (SVAS) is an inherited obstructive vascular
disease that affects the aorta, carotid, coronary and pulmonary arteries.
Previous molecular genetic data have led to the hypothesis that SVAS
results from mutations in the elastin gene, ELN. In these studies, the
disease phenotype was linked to gross DNA rearrangements (35 and 85 kb
deletions and a translocation) in three SVAS families. However, gross
rearrangements of ELN have not been identified in most cases of autosomal
dominant SVAS. To define the spectrum of ELN mutations responsible for this
disorder, we refined the genomic structure of human ELN and used this
information in mutational analyses. ELN point mutations co-segregate with
the disease in four familial cases and are associated with SVAS in three
sporadic cases. Two of the mutations are nonsense, one is a single base
pair deletion and four are splice site mutations. In one sporadic case, the
mutation arose de novo. These data demonstrate that point mutations of ELN
cause autosomal dominant SVAS.
相似文献
20.
Ruggero Ridolfi Massimiliano Petrini Laura Fiammenghi Monica Stefanelli Laura Ridolfi Michela Ballardini Giuseppe Migliori Angela Riccobon 《Journal of translational medicine》2006,4(1):36-11