全文获取类型
收费全文 | 43611篇 |
免费 | 2026篇 |
国内免费 | 219篇 |
专业分类
耳鼻咽喉 | 730篇 |
儿科学 | 714篇 |
妇产科学 | 799篇 |
基础医学 | 5611篇 |
口腔科学 | 1288篇 |
临床医学 | 3088篇 |
内科学 | 10461篇 |
皮肤病学 | 565篇 |
神经病学 | 3631篇 |
特种医学 | 1454篇 |
外科学 | 7530篇 |
综合类 | 189篇 |
一般理论 | 2篇 |
预防医学 | 1550篇 |
眼科学 | 651篇 |
药学 | 3562篇 |
中国医学 | 98篇 |
肿瘤学 | 3933篇 |
出版年
2023年 | 214篇 |
2022年 | 445篇 |
2021年 | 772篇 |
2020年 | 376篇 |
2019年 | 534篇 |
2018年 | 663篇 |
2017年 | 508篇 |
2016年 | 621篇 |
2015年 | 686篇 |
2014年 | 877篇 |
2013年 | 1154篇 |
2012年 | 1878篇 |
2011年 | 1977篇 |
2010年 | 1148篇 |
2009年 | 976篇 |
2008年 | 1878篇 |
2007年 | 2064篇 |
2006年 | 2004篇 |
2005年 | 1965篇 |
2004年 | 1931篇 |
2003年 | 1958篇 |
2002年 | 1932篇 |
2001年 | 1654篇 |
2000年 | 1806篇 |
1999年 | 1517篇 |
1998年 | 522篇 |
1997年 | 427篇 |
1996年 | 399篇 |
1995年 | 335篇 |
1994年 | 297篇 |
1993年 | 270篇 |
1992年 | 1120篇 |
1991年 | 938篇 |
1990年 | 906篇 |
1989年 | 947篇 |
1988年 | 837篇 |
1987年 | 837篇 |
1986年 | 788篇 |
1985年 | 781篇 |
1984年 | 537篇 |
1983年 | 426篇 |
1982年 | 221篇 |
1979年 | 484篇 |
1978年 | 277篇 |
1977年 | 255篇 |
1975年 | 210篇 |
1974年 | 223篇 |
1971年 | 230篇 |
1969年 | 232篇 |
1968年 | 217篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVES: The aims of this study were to characterize the microflora in crevices around titanium orthodontic anchor plates using anaerobic culture and molecular biological techniques for bacterial identification, and to compare the microbial composition between crevices around anchor plates and gingival crevices. MATERIAL AND METHODS: Samples from crevices around titanium anchor plates and healthy gingival crevices of 17 subjects (aged 20-29) were cultured anaerobically, and isolated bacteria were identified by 16S rRNA sequencing. RESULTS: The average logarithm colony-forming units/ml were 6.84, 7.51 and 8.88 in healthy anchor plate crevices, inflamed anchor plate crevices and healthy gingival crevices, respectively, indicating that the bacterial density of anchor plate crevices was lower than that of healthy gingival crevices. Of 184 strains isolated from healthy anchor plate crevices of seven subjects, 108 (59%) were anaerobic bacteria, while 73 (40%) were facultative bacteria. Predominant isolates were Gram-negative rods, such as Campylobacter (12%), Fusobacterium (10%) and Selenomonas (10%), and Gram-positive facultative bacteria, such as Actinomyces (17%) and Streptococcus (8.2%). Of 133 strains isolated from inflamed anchor plate crevices of three subjects, 110 (83%) were anaerobic bacteria, while predominant isolates were Gram-negative rods, such as Prevotella (47%), Fusobacterium (33%) and Campylobacter (16%). On the other hand, of 146 strains isolated from healthy gingival crevices of seven subjects, 98 (67%) were facultative bacteria, while 45 (31%) were anaerobic bacteria. Predominant isolates were Gram-positive facultative bacteria, such as Actinomyces (37%) and Streptococcus (20%). CONCLUSIONS: These results suggest that the environment in crevices around titanium orthodontic anchor plates is anaerobic and supportive of anaerobic growth of bacteria, which may trigger inflammation in the tissue around the plates. 相似文献
992.
Suzuki JB Misch CE Sharawy M Sarnachiaro OJ Sarnachian GO Mota L Arana G Gotta SL Gotta E Bui L 《Implant dentistry》2007,16(2):176-186
PURPOSE: To evaluate a square-thread design implant and compare the bone-implant contact percentage between immediate-loaded and nonloaded implants (controls) in nonhuman primates. MATERIALS: Five nonhuman primates each received 3 implants, with a total of 5 control implants and 10 immediate-loaded implants in posterior regions of the mouth. Ninety days after surgery (and function was appropriate), block sections of the implants were removed and sectioned in 200-mum thick pieces. The block sections were stained with modified Masson for evaluation of the bone-implant contact percentage. RESULTS: One of the immediate-loaded implants failed. The bone-implant contact percentage of control implants ranged from 50.34% to 64.13% and averaged 56.3%. The bone-implant contact percentage of immediate-loaded implants ranged from 43.23% to 75.72%, with an average of 62.4%. Two implants had lower bone-implant contact percentage than the others, and when these are not included in the evaluation, the bone-implant contact percentage average increased to 67.6%. CONCLUSIONS: Immediate-loaded implants in the nonhuman primates often have a higher bone-implant contact percentage at 90 days than unloaded implants. The bone remodeling is different for loaded implant-bone interfaces than for unloaded conditions. However, 1 immediate-loaded implant failed, and 2 implants had lower bone-implant contact percentage than controls. Therefore, although there are benefits of immediate loading, there appear to also be some risks. 相似文献
993.
Yamanashi Y Takada T Suzuki H 《The Journal of pharmacology and experimental therapeutics》2007,320(2):559-564
Previous in vivo studies including those with knockout mice suggested that Niemann-Pick C1-like 1 (NPC1L1) plays an essential role in the intestinal absorption of cholesterol. To characterize the mechanism of cholesterol uptake mediated by NPC1L1, an in vitro system reflecting the function of this transporter needs to be established. In the present study, we constructed NPC1L1 overexpressing CaCo-2 cells as an in vitro model and characterized the transport properties of NPC1L1. Immunohistochemical staining revealed that CaCo-2 cells express NPC1L1 on the apical membrane. It was also demonstrated that the uptakes of both cholesterol and beta-sitosterol are increased by NPC1L1 overexpression. In addition, the uptake of cholesterol was increased in a dose-dependent manner by an increase in the content of taurocholate in micelles, whereas micellar phosphatidylcholine showed a negative correlation with cholesterol uptake. Furthermore, it was confirmed that sterol uptake increased by NPC1L1 overexpression was inhibited by ezetimibe. We could thus establish an in vitro intestinal model to study the mechanism of NPC1L1-dependent sterol uptake and to screen drug candidates whose target is NPC1L1. 相似文献
994.
Kimura Yuta Tsunedomi Ryouichi Yoshimura Kiyoshi Matsukuma Satoshi Shindo Yoshitaro Matsui Hiroto Tokumitsu Yukio Yoshida Shin Iida Michihisa Suzuki Nobuaki Takeda Shigeru Ioka Tatsuya Hazama Shoichi Nagano Hiroaki 《Annals of surgical oncology》2022,29(12):7423-7433
Annals of Surgical Oncology - Poor prognosis in liver cancer is due to its high frequency of intrahepatic metastasis. Cancer stem-like cells (CSLCs), which possess the properties of stemness, tumor... 相似文献
995.
996.
Lasse Jrgensen Cehofski Kentaro Kojima Nobuhiro Terao Koji Kitazawa Sasikala Thineshkumar Jakob Grauslund Henrik Vorum Bent Honor 《Investigative ophthalmology & visual science》2020,61(14)
PurposeLarge-scale protein analysis may bring important insights into molecular changes following branch retinal vein occlusion (BRVO). Using proteomic techniques this study compared aqueous humor samples from patients with BRVO to age-matched controls.MethodsAqueous humor samples from treatment naive patients with BRVO complicated by macular edema (n = 19) and age-matched controls (n = 18) were analyzed with label-free quantification nano liquid chromatography – tandem mass spectrometry (LFQ nLC-MS/MS). The severity of macular edema was measured as central retinal thickness (CRT) with optical coherence tomography. Control samples were obtained prior to cataract surgery. Proteins were filtered by requiring quantification in at least 50% of the samples in each group without imputation of missing values. Significantly changed proteins were identified with a permutation-based calculation with a false discovery rate at 0.05.ResultsIn BRVO, 52 proteins were differentially expressed. Regulated proteins were involved in cell adhesion, coagulation, and acute-phase response. Apolipoprotein C-III, complement C3, complement C5, complement factor H, fibronectin, and fibrinogen chains were increased in BRVO and correlated with CRT. Fibronectin also correlated with best corrected visual acuity (BCVA) and vascular endothelial growth factor (VEGF). Monocyte differentiation antigen CD14 (CD14) and lipopolysaccharide-binding protein (LBP) were upregulated in BRVO. Contactin-1 and alpha-enolase were downregulated in BRVO and correlated negatively with CRT.ConclusionsMultiple proteins, including complement factors, fibrinogen chains, and apolipoprotein C-III, correlated with CRT, indicating a multifactorial response. Fibronectin correlated with BCVA, CRT, and VEGF. Fibronectin may reflect the severity of BRVO. The proinflammatory proteins CD14 and LBP were upregulated in BRVO. 相似文献
997.
998.
The ultrastructure and functions of platelets and megakaryocytes in 8 patients of a family with gray platelet syndrome were investigated. Hemostatic examinations on these patients revealed prolonged bleeding time, decreased platelet retention rates and decreased platelet aggregation rates induced by ADP, collagen, Ristocetin and epinephrine. Marked decreases in ATP and ADP release in response to these agents were also noted. Clinical and coagulation studies on this family suggested that the hereditary nature of the syndrome is autosomal dominant. Platelets and megakaryocytes in the peripheral and bone marrow blood smear from the patients showed peculiar gray color by May-Giemsa stain due to a deficiency of alpha-granules. Electron microscopic examinations revealed slightly enlarged platelets containing a deficient amount of alpha-granules, whereas dense bodies and mitochondria appeared normal. Several morphological abnormalities of patient's platelets, such as aggregates of dense tubular systems, circular arrays of dense tubular systems, an area of cytoplasmic sequestration with an enclosing membrane, clumps of dense material and remnants of Golgi apparatuses were recognized. Megakaryocytes showed normally developed Golgi zones, defective alpha-granule synthesis and liberation of abnormal platelets as shown in the peripheral blood smear. 相似文献
999.
M Ishii H Suzuki S Ohta M Otsuki Y Goto 《The Tohoku journal of experimental medicine》1984,142(3):299-311
SM mouse livers extracted by immersion in 1% Triton X-100, or in 1% Triton X-100 followed by 0.3 M KI were studied electron microscopically using the polyethylene glycol-embedding method. After extraction with 1% Triton X-100, almost all the structural components of hepatocytes remained intact and cytoplasmic filaments could be seen three-dimensionally by using stereopairs of micrographs. It was difficult, however, to discriminate microfilaments, intermediate-sized filaments and microtubules from one anoter in these specimes . By immersion in 1% Triton X-100 followed by 0.3 M KI, hepatocytes were extracted remaining only plasma membranes, vesicles and filaments. These filaments were approximately 10 nm in diameter, that is intermediate in size. They were branched and were connected with plasma membranes, especilly at desmosomes. The combination method of immersion extraction and PEG-embedding seems to be suitable for the electron microscopic observation of the cytoskeleton of cells in situ. 相似文献
1000.