全文获取类型
收费全文 | 5938篇 |
免费 | 473篇 |
国内免费 | 169篇 |
专业分类
耳鼻咽喉 | 60篇 |
儿科学 | 46篇 |
妇产科学 | 189篇 |
基础医学 | 1409篇 |
口腔科学 | 567篇 |
临床医学 | 327篇 |
内科学 | 659篇 |
皮肤病学 | 57篇 |
神经病学 | 644篇 |
特种医学 | 175篇 |
外国民族医学 | 1篇 |
外科学 | 703篇 |
综合类 | 758篇 |
现状与发展 | 1篇 |
预防医学 | 148篇 |
眼科学 | 150篇 |
药学 | 279篇 |
4篇 | |
中国医学 | 229篇 |
肿瘤学 | 174篇 |
出版年
2024年 | 14篇 |
2023年 | 85篇 |
2022年 | 116篇 |
2021年 | 285篇 |
2020年 | 209篇 |
2019年 | 183篇 |
2018年 | 194篇 |
2017年 | 191篇 |
2016年 | 179篇 |
2015年 | 206篇 |
2014年 | 348篇 |
2013年 | 380篇 |
2012年 | 246篇 |
2011年 | 264篇 |
2010年 | 263篇 |
2009年 | 244篇 |
2008年 | 247篇 |
2007年 | 286篇 |
2006年 | 244篇 |
2005年 | 216篇 |
2004年 | 191篇 |
2003年 | 202篇 |
2002年 | 154篇 |
2001年 | 170篇 |
2000年 | 111篇 |
1999年 | 113篇 |
1998年 | 120篇 |
1997年 | 113篇 |
1996年 | 95篇 |
1995年 | 90篇 |
1994年 | 82篇 |
1993年 | 74篇 |
1992年 | 73篇 |
1991年 | 50篇 |
1990年 | 67篇 |
1989年 | 61篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 55篇 |
1985年 | 49篇 |
1984年 | 40篇 |
1983年 | 33篇 |
1982年 | 27篇 |
1981年 | 29篇 |
1980年 | 27篇 |
1979年 | 17篇 |
1978年 | 17篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 5篇 |
排序方式: 共有6580条查询结果,搜索用时 46 毫秒
81.
背景:有研究显示中国人膝关节胫骨近端前后径和横径均小于美国高加索人,所以在膝关节形态学方面存在一定差异,因此常发生进口假体系统应用于国人后出现匹配度不高的现象。目的:测量中国人和美国人股骨远端、胫骨近端的几何形态学参数,比较其差异。方法:选择北京清华长庚医院骨科拟行前交叉韧带重建的中国汉族患者50例,以及美国匹兹堡大学运动医学中心拟行前交叉韧带重建的高加索白人后裔患者40例,对90例受试者膝关节进行CT扫描,使用AW Volume Share 5软件进行三维重建,利用Geomagic软件对胫骨近端和股骨远端的各项参数进行测量。结果与结论:①股骨近端测量参数中,中国人的外侧胫骨平台内外径小于美国人(P=0.027),外侧胫骨平台后倾角大于美国人(P<0.05);两组间胫骨平台内外径、内侧胫骨平台外径、内侧胫骨平台前后径、外侧胫骨平台前后径与内侧胫骨平台后倾角比较差异均无显著性意义(P>0.05);②股骨远端测量参数中,中国人的股骨远端横径、外侧髁内外径、内侧髁前后径、外侧髁前后径及髁间窝高度均小于美国人(P<0.05),股骨外翻角大于美国人(P<0.05);两组间内侧髁内外径、髁间窝宽度及滑车沟宽度比较差异无显著性意义(P>0.05);③结果表明,中国人与美国人在膝关节形态学的多个参数存在差异,有必要针对中国人设计更为个体化的膝关节假体。 相似文献
82.
应用扫描电镜观察了22例糖尿病人4400个红细胞形态的异常百分比,并测定红细胞的渗透脆性。结果表明随着糖尿病病程延长、糖化血红蛋白升高,口形、嵴形红细胞的百分比明显升高(2.64±1.27比4.29±1.03,P<0.001),细胞渗透脆性明显上升(0.17±0.04比0.33±0.17,P<0.05)。提示,糖尿病人异常形态红细胞的出现不仅与红细胞的能量代谢障碍外,还可能与红细胞所处的高血糖、高血脂、高血液粘度的环境有关。而影响红细胞的渗透脆性的因素较为复杂,红细胞的圆形隆起在降低其渗透脆性方面起了重要作用。 相似文献
83.
Primary non-Hodgkin's lymphoma of the intestine: a morphological, immunohistochemical and clinical study of 31 Chinese cases 总被引:5,自引:0,他引:5
Thirty-one cases of primary non-Hodgkin's lymphoma of the intestine were investigated. Twenty-one were of B-cell and 10 of T-cell origin. The B-cell lymphomas comprised two cases of low-grade B-cell lymphoma of mucosaassociated lymphoid tissue (MALT), one of centroblastic/centrocytic type, three of high-grade B-cell lymphoma coexisting with a low-grade B-cell lymphoma of MALT, nine of centroblastic, three of immunoblastic and three of Burkitt type. Of the T-cell lymphomas, eight were of pleomorphic medium-to large-sized cell type and two of large cell anaplastic type. All the B-cell lymphomas expressed CD20 (L26) and/or Ki-B5; in six there was monotypic immunoglobulin light chain restriction. Membrane positivity for CD45RO (UCHL1) was observed in the 10 cases of T-cell lymphoma, but the tumour cells did not express monocyte-macrophage markers. Clinically, the patients with T-cell lymphomas were usually young males with constitutional symptoms and their prognosis was significantly worse than those of patients with intestinal B-cell lymphoma. 相似文献
84.
Propene was polymerised at high temperatures (up to 90 °C) using rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO as the catalytic system. The increasing deactivation reaction rate of the catalyst for polymerisations above 60 °C was less for a silica supported catalyst compared with the homogeneous one. The isotacticity of polypropene decreases from 99 to 96%. Also the morphology changes with different temperatures.
85.
Janice S. Lee Carol W. Bassim Harvey Kushner Ann G. Carr Pamela J. Gardner Laura A. Harney Kris Ann P. Schultz Douglas R. Stewart 《American journal of medical genetics. Part A》2019,179(9):1820-1825
Pathogenic germline variation in the microRNA processing gene DICER1 gives rise to an autosomal dominant, tumor‐predisposition disorder. Conditional deletion of Dicer1 in murine dental epithelium shows that it controls tooth patterning, size, number, and shape. The human dental phenotype of people with germline pathogenic variation in DICER1 is unknown. DICER1‐carriers (n = 57) and family controls (n = 55) were evaluated at the NIH Clinical Center dental clinic as part of a comprehensive medical evaluation. Digital panoramic radiographs, bite‐wing radiographs, and oral photographs were collected. A single observer, blind to DICER1 status, reviewed the dental records and determined the presence or absence of 11 dental characteristics as described in the clinic notes, radiographs, or oral photographs. Subjective phenotypes were reviewed on radiographs by two examiners (blind to DICER1 status) for the presence or absence of the dental characteristics to reduce inconsistencies. By simple association, bulbous crown, periodontitis, and taurodontism were all significant (p < .05). Logistic regression with chi‐square maximum likelihood estimates showed that bulbous crown and periodontitis remained significant. Recognition of these phenotypes may aid identification of individuals and families at risk for DICER1‐associated neoplasms. These findings may also guide dental care for individuals with germline DICER1 pathogenic variation. 相似文献
86.
Min G Christensen S Marcussen N Osterby R 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2000,108(10):652-662
The effects of long-term lithium administration on glomerular structure and intervention with angiotensin converting enzyme inhibitor (ACEI) were studied in rats. Male Wistar rats were fed a lithium-containing diet (Li) or control diet (C) for 16 weeks postnatally. Li-treated rats developed renal failure, hypertension and proteinuria. During the subsequent 24 weeks, subgroups were treated with ACEI. The kidneys were fixed by perfusion, and tissue blocks were serially cut for estimation of glomerular volume and glomerular characteristics by light microscopy. Mesangial and mesangial matrix volume fractions, surface density of capillary walls, basement membrane thickness and foot process width (FPW) were measured by electron microscopy. Glomerular volume was decreased in Li-rats, with increased intra-individual variation. In all Li-rats, some glomeruli (mean 27%) were abnormal, with severe changes in only three rats. Ultrastructural parameters obtained by systematic sampling of three glomeruli in each rat showed no differences among groups. Among Li-treated animals there was a significant correlation between FPW and albumin excretion per unit filtration surface, and between filtration surface per glomerulus and inulin clearance. In conclusion, long-term lithium administration to newborn rats caused marked changes in glomerular volume which were not associated with measurable changes in structural parameters. No effect of ACEI-treatment was detectable. 相似文献
87.
R. W. Rhoades W. H. Rohrer R. D. Mooney S. Ruiz 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1989,76(1):229-238
Summary We have employed intracellular injection of horseradish peroxidase (HRP) and 3-dimensional, computer-assisted reconstruction to delineate the organization of the dendrites of horizontal cells in the superficial laminae (the stratum griseum superficiale-SGS, and stratum opticum-SO) of the hamster's superior colliculus. Fifteen well-filled cells were analyzed. The dendrites of these cells were generally parallel to the frontal plane. An average of 74.8±13.0% of the total dendritic arbor of the recovered horizontal cells was located within 30° of this plane. The long axis of horizontal cell dendritic trees deviated an average (mean ± s.d.) of 21.7±13.2° from the frontal plane and the average extent of the dendritic tree in this plane was 637±216 m. This differed significantly from the average dendritic extent in the rostrocaudal axis (358±146 m, p<0.001). In some cases, portions of the dendritic arbors of horizontal cells appeared to be oriented along lines of isoelevation or isoazimuth of the visual field representation in the superficial laminae. For other cells, there was no clear relationship between dendritic orientation and the visual field map. 相似文献
88.
Demir Weusten AY Groothuis PG Dunselman GA de Goeij AF Arends JW Evers JL 《Human reproduction (Oxford, England)》2000,15(7):1462-1468
In a previous study on the pathogenesis of endometriosis, we observed that constituents of menstrual effluent induce morphological alterations in human mesothelial cells. In this study, we investigated whether these alterations were associated with apoptosis or necrosis or were the result of cellular remodelling. After overnight incubation of confluent monolayers of human omental mesothelial cells (HOMEC) with conditioned media prepared from menstrual effluent shed anterogradely, severe alterations in morphology were observed. Typical polygonal mesothelial cell cultures at confluency acquired elongated spindle morphology, resulting in gaps between the cells. In contrast, mesothelial cells from the control groups receiving culture medium only, retained a normal morphology. Immunofluorescence staining revealed that cytokeratin, vimentin and actin filaments were still present, homogeneously distributed in the cell cytoplasm following changes in morphology. To evaluate whether the morphological alterations were associated with apoptosis and/or necrosis, the cells were stained with the M30 CytoDeath antibody or annexin V with propidium iodide and analysed using flow cytometry. The results showed that only a small percentage (1-7%) of the affected HOMEC were undergoing apoptosis or necrosis. We conclude that the profoundly altered morphology of HOMEC is a result of cellular remodelling and that the role of apoptosis and necrosis is negligible. Soluble paracrine factors released by cells isolated from menstrual effluent shed anterogradely may induce a reorganization of the cytoskeleton. As a result, the underlying basement membrane will be exposed and the mesothelium may no longer prevent implantation of endometrium shed retrogradely into the peritoneum, thus facilitating the development of endometriosis. 相似文献
89.
Inoculation of fertile Pekin duck eggs with diluted serum containing DHBV into eggs incubated for 24 h and into the extra-embryonic cavities of 14-day-old embryos resulted in a high proportion of viraemic ducklings irrespective of the route of inoculation. Long-term observation of som of the ducks established that the viraemia induced experimentally is long-lasting and has persisted for periods up to 16 mth post-hatch. Separation of DHBV from the plasma of carrier ducks by rate zonal centrifugation was examined by DNA polymerase (DNAP) activity. Particles in the fraction with peak DNAP activity had a buoyant density of 1.16 g X cm-3 in sucrose and an estimated sedimentation coefficient, S20.w of 77. DHBV particles, the morphology of which could be resolved under the electron microscope, consisted of a coat (about 10 nm in thickness) surrounding a core with a diameter measuring 40 nm but not 27 nm as previously reported. Spike-like projections were found on the surface of the core as described previously by W.S. Mason, G. Seal and J. Summers, 1980, J. Virol. 36, 829-836. 相似文献
90.
The measurement of CA 125 and placental protein 14 in uterine flushings in women with recurrent miscarriage; relation to endometrial morphology 总被引:2,自引:2,他引:2
Dalton C.F.; Laird S.M.; Serle E.; Saravelos H.; Warren M.A.; Li T.C.; Bolton A.E. 《Human reproduction (Oxford, England)》1995,10(10):2680-2684
The concentrations of CA 125 and placental protein 14 (PP14)were measured in uterine flushings obtained throughout the lutealphase of the cycle from eight normal fertile women. The concentrationsof both proteins increased in a similar pattern throughout theluteal phase of the cycle, with the most dramatic increase occurring6 days after their luteinizing hormone surge (day LH +6). However,a greater variation in CA 125 concentrations was seen comparedto that seen for PP14. The concentrations were compared to thoseobtained on day LH + 7 of the cycle from a group (n equals;35) of women with recurrent miscarriage. The ranges in concentrationof PP14 and CA 125 in the flushings of fertile and recurrentmiscarriage patients were very similar. However, a greater proportionof women with recurrent miscarriage (55%) had low concentrations(<5 ng/ml) of PP14 than in the control group (12.5%) andthe concentrations of PP14 in the uterine flushings were significantlyless (P < 0.05) in women with recurrent miscarriage comparedto the normal fertile group. There was no significant differencein the concentrationof CA 125 in the uterine flushings betweenthe two groups. Histological observation of the endometrialbiopsy samples from recurrent miscarriage patients gave menstrualcycle datings that ranged from day LH +2.5 to LH +6.5 with retardedendometrium (;day LH +5) in 12 of 35 (34%) patients. Of these12 patients, 10 (83%) had low PP14 concentrations and six (50%)had low CA 125 concentrations in their uterine flushings. Inthe recurrent miscarriage patients with histologically normal(sequals; day LH +5) endometrial development, 10 out of 23 (43%)also had low PP14 concentrations and 8 out of 23 (35%) had lowCA 125 in their uterine flushings. The results suggest thatPP14 is better than CA 125 as a marker for endometrial functionin this group of women. In some cases (52%) the low concentrationsof PP14 in the uterine flushings couldbe explained by retardedendometrial development but for the others the reduction inPP14 concentration in the uterine flushing was not associatedwith retardation of endometrial development. 相似文献