全文获取类型
收费全文 | 86489篇 |
免费 | 7806篇 |
国内免费 | 5648篇 |
专业分类
耳鼻咽喉 | 890篇 |
儿科学 | 919篇 |
妇产科学 | 1268篇 |
基础医学 | 10908篇 |
口腔科学 | 1452篇 |
临床医学 | 11725篇 |
内科学 | 12731篇 |
皮肤病学 | 1062篇 |
神经病学 | 4624篇 |
特种医学 | 3218篇 |
外国民族医学 | 56篇 |
外科学 | 8897篇 |
综合类 | 11834篇 |
现状与发展 | 23篇 |
一般理论 | 22篇 |
预防医学 | 5434篇 |
眼科学 | 3055篇 |
药学 | 9123篇 |
87篇 | |
中国医学 | 4557篇 |
肿瘤学 | 8058篇 |
出版年
2024年 | 290篇 |
2023年 | 1324篇 |
2022年 | 3441篇 |
2021年 | 4413篇 |
2020年 | 3260篇 |
2019年 | 3068篇 |
2018年 | 3230篇 |
2017年 | 2711篇 |
2016年 | 2765篇 |
2015年 | 4002篇 |
2014年 | 5025篇 |
2013年 | 4439篇 |
2012年 | 6492篇 |
2011年 | 6924篇 |
2010年 | 4327篇 |
2009年 | 3268篇 |
2008年 | 4528篇 |
2007年 | 4385篇 |
2006年 | 4499篇 |
2005年 | 4286篇 |
2004年 | 2902篇 |
2003年 | 2667篇 |
2002年 | 2214篇 |
2001年 | 1857篇 |
2000年 | 1857篇 |
1999年 | 2151篇 |
1998年 | 1346篇 |
1997年 | 1318篇 |
1996年 | 988篇 |
1995年 | 938篇 |
1994年 | 794篇 |
1993年 | 492篇 |
1992年 | 603篇 |
1991年 | 511篇 |
1990年 | 480篇 |
1989年 | 418篇 |
1988年 | 376篇 |
1987年 | 300篇 |
1986年 | 249篇 |
1985年 | 210篇 |
1984年 | 130篇 |
1983年 | 86篇 |
1982年 | 42篇 |
1981年 | 51篇 |
1980年 | 29篇 |
1979年 | 63篇 |
1978年 | 22篇 |
1974年 | 27篇 |
1973年 | 18篇 |
1968年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
A K Seedat M J Sun J D Grimbeek E Cumber 《The Journal of the Dental Association of South Africa》1989,44(10):407-408
A patient presented at the Department of Orthodontics, Medunsa Dental Hospital, complaining of "crooked teeth". On clinical examination it was evident that several teeth were unerupted. The absence of a normal eruption pattern of certain teeth as well as delayed eruption of others, resulted in a malocclusion. 相似文献
92.
Tumor-induced osteomalacia and rickets 总被引:4,自引:0,他引:4
M A Nuovo H D Dorfman C C Sun S A Chalew 《The American journal of surgical pathology》1989,13(7):588-599
Tumor-induced osteomalacia is a clinicopathological entity in which vitamin D-resistant osteomalacia or rickets occurs in association with a tumor. A total of 72 cases (three current, 69 from review of literature) has been reported to date. Men and women are equally affected. The majority are adults over 30 years old who exhibit progressive lower leg and back pain. Forty bone and 31 soft-tissue tumors were responsible for this syndrome; two-thirds occurred in the extremities. Chemical findings are typical: low serum phosphorus, normal serum calcium, and elevated alkaline phosphatase. Serum levels of 1,25-dihydroxyvitamin D were low or undetectable. Histologically, more than a third were classified as vascular tumors, and half of these cases were hemangiopericytomas that were distributed equally between bone and soft tissues. Other common diagnoses included nonossifying fibromas, "mesenchymal" and giant-cell tumor variants. Features common to all tumors were prominent vascularity, and giant and primitive stromal cells. Only 10 were histologically malignant. Ultrastructural studies have not shown any secretory granules suggestive of a hormone-secreting tumor. It is clear, however, that the tumor is responsible for the osteomalacia because the complete removal generally results in a dramatic reversal of all symptoms and signs. 相似文献
93.
94.
Mochizuki S Abe Y Chinzei T Isoyama T Ono T Saito I Guba P Karita T Sun YP Kouno A Suzuki T Baba K Mabuchi K Imachi K 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2000,46(4):500-504
An undulation pump is a special rotary blood pump in which rotation of a brushless DC motor is transformed to an undulating motion by a disc in the pump housing attached by means of a special link mechanism. In the blood pump, a closed line between the disc and housing moves from the inlet to the outlet by this undulating disc motion, which sucks and pushes the blood from the inlet to the outlet. Because the same phenomena occurs at both sides of the disc, a continuous flow is obtained when the motor rotational speed is constant. The pump flow pattern can be easily changed from continuous flow to pulsatile flow by controlling the motor drive current pattern. A seal membrane made of segmented polyurethane protects the blood from invading the link mechanism as well as the motor. UPTAH is fabricated with two undulation pumps and two brushless DC motors. Its size is 75 mm in diameter and 80 mm long, and it has one of the great advantage of no compliance chamber required in the system. UPTAHs were implanted under cardiopulmonary bypass (CPB) into the chest cavities of 16 goats, each weighing between 41 and 72 kg. No anticoagulant and antiplatelet agent was used after the surgery. The left atrial pressure was automatically controlled to prevent its elevation and sucking of the atrial wall into the atrial cuff. The following results were obtained: (1) UPTAHs fit well into all the goats; (2) the longest survival was 19.8 days, the cause of death was bleeding from the aortic anastomosis; (3) No thrombus was observed in the blood pump despite no anticoagulant use. Hemolysis depended upon the length of CPB during surgery. When CPB time was within 2 hours, hemolysis level returned to baseline within a few days of the surgery. UPTAH is a promising implantable TAH, because of its small size and easy controllability. 相似文献
95.
In addition to their well-characterized role in allergic inflammation, recent data confirm that mast cells play a more extensive role in a variety of viral infections. The contribution of mast cells to Newcastle disease pathogenesis has not been investigated. We evaluated mast cell activity after Newcastle disease virus (NDV) infection in specific pathogen free chickens using cytochemical and immunocytochemical analyses. The results were as follows. Severe tissue damage was observed in the proventriculus, duodenum, jejunum and caecal tonsil, and NDV antigens were detected and presented extensively in these tissues. Second, in the NDV-infected group, the mast cell population was increased markedly in the proventriculus, duodenum, jejunum and caecal tonsil at 24, 48, 72 and 96 h after infection (P<0.01). However, very few mast cells were observed in those same tissues in the control. More intriguingly, the greatest number of mast cells was found in the proventriculus, which also showed the greatest level of NDV antigens. Third, the content of tryptase was significantly higher (P<0.01) in the NDV-infected group compared with the control from 24 to 96 h post infection). Furthermore, as an important protease released by mast cells, tryptase had a positive correlation with mast cell distribution. These data indicated that mast cells were involved in the response to NDV. Our results also suggested that the broad range of mast cell mediators might have a role in the pathology of Newcastle disease. 相似文献
96.
Sun JS Lin FH Tsuang YH Chen LT Hong RC Chang WH Liu HC 《Journal of biomedical materials research》2000,52(3):509-516
Cytokines produced by macrophages in the periprosthetic membranes surrounding joint replacements have been implicated as causal agents in osteolysis and prosthetic loosening. The present study characterizes the response of human peripheral blood monocytes to titanium particles. Monocytes were obtained from donated blood and were cultured in the presence of different-sized titanium particles. Exposure to titanium-aluminum-vanadium particles significantly changed the release of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-1 (IL-1), whereas there was no significant effect on the release of prostaglandin E(2) (PGE(2)). When monocytes were cultured with particles, the titanium alloy particles induced significantly more release of TNF-alpha and less IL-1 secretion. Ciprofloxacin inhibited production of TNF-alpha, IL-6, IL-1, and PGE(2) in human monocytes exposed to titanium particles. In contrast to ciprofloxacin, indomethacin was not a potent inhibitor of TNF-alpha production but potentiated IL-6 production in titanium-stimulated monocytes. Indomethacin had no effect on the production of IL-1 and was a potent inhibitor of PGE(2) production in titanium-stimulated monocytes. Pentoxifylline had an inhibitor effect on TNF-alpha production in titanium-stimulated monocytes. Pentoxifylline potentiated IL-6 and IL-1 production in monocytes exposed to titanium particles and had a biphasic effect on the PGE(2) production. The results of this study support our hypothesis that human monocytes release bone resorption mediators after in vitro exposure to TiAlV alloy particles. The results also demonstrate the differences of bone-resorbing mediators in response to different wear particle size. The pharmacologic agents (ciprofloxacin, pentoxifylline, and indomethacin) that can modulate the release of bone resorbing mediators such as PGE(2), TNF-alpha, IL-1, and IL-6 release from human monocytes. The results help to elucidate the differences in cellular response to wear particles but may not be directly transposed to the human situation. 相似文献
97.
为探讨细胞外间质主要成分透明质酸(HA)与层粘连蛋白(LN)在缺血性股骨头坏死(INFH)中的生理病理过程及临床价值,采用放射免疫分析法对45例不同病因的INFH患者进行了血清HA与LN的定量分析,并与30例正常人对照。结果显示,INFH患者血清HA含量极显著地高于对照组(t=3-29;P<0-01)。尤以激素性INFN增高最为显著(t=3-62;P<0-01)。INFH患者LN含量亦明显高于对照组(t=2-84;P<0-01)。同时,HA与LN含量增高与病程发展密切相关。故定量检测HA与LN可作为INFH早期诊断及判断预后的良好指标 相似文献
98.
Endoscopic sclerotherapy as compared with endoscopic ligation for bleeding esophageal varices. 总被引:30,自引:0,他引:30
G V Stiegmann J S Goff P A Michaletz-Onody J Korula D Lieberman Z A Saeed R M Reveille J H Sun S R Lowenstein 《The New England journal of medicine》1992,326(23):1527-1532
BACKGROUND. Endoscopic sclerotherapy is an accepted treatment for bleeding esophageal varices, but it is associated with substantial local and systemic complications. Endoscopic ligation, a new form of endoscopic treatment for bleeding varices, may be safer. We compared the effectiveness and safety of the two techniques. METHODS. In this randomized trial we compared endoscopic sclerotherapy and endoscopic ligation in 129 patients with cirrhosis who had proved bleeding from esophageal varices. Sixty-five patients were treated with sclerotherapy, and 64 with ligation. Initial treatment for acute bleeding was followed by elective retreatment to eradicate varices. The patients were followed for a mean of 10 months, during which we determined the incidence of complications and recurrences of bleeding, the number of treatments needed to eradicate varices, and survival. RESULTS. Active bleeding at the first treatment was controlled by sclerotherapy in 10 of 13 patients (77 percent) and by ligation in 12 of 14 patients (86 percent). Slightly more sclerotherapy-treated patients had recurrent hemorrhage during the study (48 percent vs. 36 percent for the ligation-treated patients, P = 0.072). The eradication of varices required a lower mean (+/- SD) number of treatments with ligation (4 +/- 2 vs. 5 +/- 2, P = 0.056) than with sclerotherapy. The mortality rate was significantly higher in the sclerotherapy group (45 percent vs. 28 percent, P = 0.041), as was the rate of complications (22 percent vs. 2 percent, P less than 0.001). The complications of sclerotherapy were predominantly esophageal strictures, pneumonias, and other infections. CONCLUSIONS. Patients with cirrhosis who have bleeding esophageal varices have fewer treatment-related complications and better survival rates when they are treated by esophageal ligation than when they are treated by sclerotherapy. 相似文献
99.
100.
Nwanegbo E Vardas E Gao W Whittle H Sun H Rowe D Robbins PD Gambotto A 《Clinical and diagnostic laboratory immunology》2004,11(2):351-357
One of the major limitations of the use of adenoviruses as gene therapy vectors is the existence of preformed immunity in various populations. Recent studies have linked failure of adenoviral gene therapy trials to the presence of antiadenoviral neutralizing antibodies (NAb). Understanding the distribution and specificity of such antibodies will assist in the design of successful recombinant adenoviral gene therapies and vaccines. To assess the prevalence of NAb to adenovirus serotypes 5 and 35 (Ad5 and Ad35), we analyzed serum samples from adult immunocompetent individuals living in The Gambia, South Africa, and the United States by using a neutralization assay. Serum samples were incubated with A549 lung carcinoma cells and adenoviruses encoding enhanced green or yellow fluorescent proteins; results were analyzed by fluorescence microscopy and flow cytometry. Using this technique, we found a high prevalence of NAb against Ad5 in Gambian, South African, and U.S. subjects at both low and high titers. Conversely, all subjects displayed a low prevalence of NAb to Ad35; when present, anti-Ad35 NAb were seen at low titers. Because of the ability of adenoviruses to elicit systemic and mucosal immune responses, Ad35 with its low NAb prevalence appears to be an attractive candidate vector for gene therapy applications. 相似文献