全文获取类型
收费全文 | 3101篇 |
免费 | 213篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 76篇 |
儿科学 | 61篇 |
妇产科学 | 78篇 |
基础医学 | 431篇 |
口腔科学 | 44篇 |
临床医学 | 332篇 |
内科学 | 563篇 |
皮肤病学 | 58篇 |
神经病学 | 268篇 |
特种医学 | 129篇 |
外科学 | 614篇 |
综合类 | 13篇 |
预防医学 | 175篇 |
眼科学 | 67篇 |
药学 | 188篇 |
肿瘤学 | 225篇 |
出版年
2022年 | 32篇 |
2021年 | 59篇 |
2020年 | 31篇 |
2019年 | 41篇 |
2018年 | 72篇 |
2017年 | 43篇 |
2016年 | 68篇 |
2015年 | 85篇 |
2014年 | 103篇 |
2013年 | 127篇 |
2012年 | 171篇 |
2011年 | 201篇 |
2010年 | 126篇 |
2009年 | 114篇 |
2008年 | 144篇 |
2007年 | 134篇 |
2006年 | 168篇 |
2005年 | 147篇 |
2004年 | 111篇 |
2003年 | 128篇 |
2002年 | 103篇 |
2001年 | 68篇 |
2000年 | 104篇 |
1999年 | 90篇 |
1998年 | 44篇 |
1997年 | 18篇 |
1996年 | 28篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 45篇 |
1991年 | 44篇 |
1990年 | 46篇 |
1989年 | 30篇 |
1988年 | 50篇 |
1987年 | 35篇 |
1986年 | 38篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 22篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1975年 | 17篇 |
1974年 | 16篇 |
1973年 | 22篇 |
1972年 | 16篇 |
1970年 | 16篇 |
1968年 | 18篇 |
排序方式: 共有3322条查询结果,搜索用时 15 毫秒
1.
2.
Inhibition of vessel allograft rejection by endothelial removal. Morphologic and ultrastructural changes. 总被引:1,自引:1,他引:0 下载免费PDF全文
M A Galumbeck F P Sanfilippo P O Hagen A V Seaber J R Urbaniak 《Annals of surgery》1987,206(6):757-764
The vascular endothelium plays an important and complex role in vascular allograft rejection. Antigens expressed by the endothelium can act to promote and be the target of rejection reactions, which often lead to thrombosis and ischemic necrosis of the allograft. In this study, segments of femoral artery and femoral vein with or without endothelium were grafted between allogenic or autologous control rats. Immunocompetent Lewis (RT1(1] recipient rats were randomly selected for groups (N = 14 for each) receiving the following: ACI- (RT1a) allografts with intact endothelium, allografts with endothelium removed before operation, autografts with endothelium, and autografts with endothelium removed. Rejection was assessed by graft patency as well as morphologic and ultrastructural changes. At 5 days, the allografts with intact endothelium were totally occluded, whereas allografts without endothelium remained patent, as did autologous control grafts with or without endothelium. Two additional groups (N = 14 each) receiving the de-endothelialized allografts or autografts were examined at 120 days after operation, revealing that grafts in both groups were still patent and had been re-endothelialized. These findings indicate that physical removal of vascular endothelium may depress vessel allograft rejection without immunosuppressive therapy. 相似文献
3.
Dysphagia was studied in 29 patients after implantation of an Angelchik prosthesis for persistent reflux oesophagitis. The incidence of postoperative dysphagia occurred after three months (61%), six months (45%), and one year or more (41%). Severe dysphagia necessitated removal of the prosthesis in five patients (17%). The reoperative findings with regard to a possible explanation of dysphagia are discussed, and comparison is made with reports in literature. Implantation of the Angelchik prosthesis seems only indicated for the treatment of intractable reflux oesophagitis in patients where other operative modalities failed and who are at high risk for operation. The Nissen fundoplication remains the operation of choice. 相似文献
4.
The synthesis of the title compounds starting from 2-Chlormethylbenzdioxan and Tetrahydroisochinolines is presented. Their actions on the platelet aggregation and the inhibition of alpha-adrenoceptors at the isolated rabbit aorta and the vas deferens of the guinea pig were investigated. 相似文献
5.
Abstract Simultaneous bilateral avulsions of the tibial tuberosity are rare injuries. The authors found only five reported cases in
the orthopedic literature. We add a further case of bilateral avulsions of the tibial tuberosity with the longest reported
follow-up. 相似文献
6.
L. J. Stovner J.-A. Zwart K. Hagen G. M. Terwindt J. Pascual 《European journal of neurology》2006,13(4):333-345
The present review of epidemiologic studies on migraine and headache in Europe is part of a larger initiative by the European Brain Council to estimate the costs incurred because of brain disorders. Summarizing the data on 1-year prevalence, the proportion of adults in Europe reporting headache was 51%, migraine 14%, and 'chronic headache' (i.e. > or =15 days/month or 'daily') 4%. Generally, migraine, and to a lesser degree headache, are most prevalent during the most productive years of adulthood, from age 20 to 50 years. Several European studies document the negative influence of headache disorders on the quality of life, and health-economic studies indicate that 15% of adults were absent from work during the last year because of headache. Very few studies have been performed in Eastern Europe, and there are also surprisingly little data on tension-type headache from any country. Although the methodology and the quality of the published studies vary considerably, making direct comparisons between different countries difficult, the present review clearly demonstrates that headache disorders are extremely prevalent and have a vast impact on public health. The data collected should be used as arguments to increase resources to headache research and care for headache patients all over the continent. 相似文献
7.
L B Schwartz Z S Radic M K O'Donohoe R L McCann E M Mikat P O Hagen 《Blood vessels》1991,28(6):511-519
Previous studies have demonstrated that vein storage in normal saline leads to significant mechanical morphological, and biochemical aberrations. However, little information is available regarding the functional damage that occurs. The purpose of this study was to evaluate the effect of saline storage on venous smooth muscle and endothelial function. Segments of ten external jugular veins from male New Zealand White rabbits were placed nondistended in either modified Krebs solution at 37 degrees C (Krebs-stored, KS) or heparinized normal saline at room temperature (saline-stored, SS) for 1 h. Segments 4 mm in length were then simultaneously studied in vitro under isometric tension. There was no difference in maximum tension or sensitivity to either bradykinin or histamine. Acetylcholine-induced relaxation in KS segments was not significantly different from relaxation in a historical cohort of nonstored segments (nonstored 87.4 +/- 1.0% vs. KS 84.5 +/- 2.0%; p = NS). However, there were significant attenuations in SS segment endothelium-dependent relaxation in response to both acetylcholine (KS 84.5 +/- 2.0% vs. SS 76.4 +/- 2.7%, p less than 0.02) and adenosine diphosphate (KS 47.9 +/- 2.9% vs. SS 40.6 +/- 3.7%, p less than 0.002). Relaxant responses to sodium nitroprusside (endothelium-independent) were not significantly different in the two groups (KS 94.6 +/- 1.6% vs. SS 95.7 +/- 2.2%; p = NS). Electron microscopic evaluation of SS segments revealed endothelial cell disruption with cellular edema and loss of intact junctions.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
8.
Summary
Forty-one patients demonstrating clinical symptoms for cerebral infarction were investigated by magnetic resonance imaging
with diffusion-weighted echo-planar imaging (DWI) and T2-weighted imaging (T2WI). In 8 patients only DWI showed the cerebral
lesions clearly. One patient with positive DWI and T2WI suffered from HSV encephalitis. DWI is superior to T2WI in assessment
of small cortical infarcts and cerebral infarction in patients with preexisting vascular lesions. DWI is not specific, so
other causes like cerebral hematoma and encephalitis have to be considered.
相似文献
9.
Depression and anxiety disorders associated with headache frequency. The Nord‐Trøndelag Health Study
J.‐A. Zwart G. Dyb K. Hagen K. J.
degrd A. A. Dahl G. Bovim L. J. Stovner 《European journal of neurology》2003,10(2):147-152
The aim of this large cross‐sectional population‐based study was to examine the association between migraine, non‐migrainous headache and headache frequency with depression, and anxiety disorders. From 1995 to 1997, all 92 566 inhabitants aged 20 years and above in Nord‐Trøndelag County in Norway were invited to participate in the Nord‐Trøndelag Health Study (‘Helseundersøkelsen i Nord‐Trøndelag’ = HUNT‐2). A total of 64 560 participated, whereof 51 383 subjects (80%) completed a headache questionnaire that was included. Of these 51 383 individuals, 47 257 (92%) completed the depression subscale items and 43 478 (85%), the anxiety subscale items of the Hospital Anxiety and Depression Scale (HADS). Associations were assessed in multivariate analyses, estimating prevalence odds ratios (OR) with 95% confidence intervals (CI). Depression and anxiety disorders as measured by HADS, were significantly associated with migraine (OR = 2.7, 95% CI 2.3–3.2; OR = 3.2, 95% CI 2.8–3.6) and non‐migrainous headache (OR = 2.2, 95% CI 2.0–2.5; OR = 2.7, 95% CI 2.4–3.0) when compared with headache‐free individuals. The association was stronger for anxiety disorders than for depression. The ORs for depression and anxiety disorders amongst both migraine and non‐migrainous sufferers increased with increasing headache frequency. Depression and anxiety disorders are associated with both migraine and non‐migrainous headache, and this association seems more dependent on headache frequency than diagnostic category. 相似文献
10.
Mutations in the lambda repressor gene cI (710 bp) were induced by 60Co-gamma radiation in dissolved lambda phage DNA. After in vitro DNA packaging to lambda phage particles (pack phage) and phenotypic expression of the mutants, DNA was sequenced directly. Two-thirds of mutations were located in the amino terminus region of the gene without any signs of hotspots. Changes consisted of (+1) insertions (25%) and base substitutions (75%). Transitions were exclusively G/C to A/T. Transversions were mostly G/C to C/G and few G/C to T/A. We did not find A/T to T/A transversions, A/T to G/C transitions, deletions and gross rearrangements. In most of the base substitutions a pre-existing base pair had been replaced by an A/T pair; this might come from 'non-instructional sites' like abasic sites. Several mechanisms for base substitutions are considered. 相似文献