全文获取类型
收费全文 | 1525篇 |
免费 | 24篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 14篇 |
妇产科学 | 21篇 |
基础医学 | 353篇 |
口腔科学 | 77篇 |
临床医学 | 91篇 |
内科学 | 121篇 |
皮肤病学 | 104篇 |
神经病学 | 207篇 |
特种医学 | 41篇 |
外科学 | 93篇 |
综合类 | 196篇 |
预防医学 | 51篇 |
眼科学 | 105篇 |
药学 | 72篇 |
中国医学 | 12篇 |
肿瘤学 | 13篇 |
出版年
2022年 | 27篇 |
2021年 | 27篇 |
2020年 | 20篇 |
2019年 | 30篇 |
2018年 | 27篇 |
2017年 | 24篇 |
2016年 | 26篇 |
2015年 | 42篇 |
2014年 | 47篇 |
2013年 | 151篇 |
2012年 | 67篇 |
2011年 | 74篇 |
2010年 | 70篇 |
2009年 | 64篇 |
2008年 | 64篇 |
2007年 | 49篇 |
2006年 | 47篇 |
2005年 | 71篇 |
2004年 | 42篇 |
2003年 | 54篇 |
2002年 | 47篇 |
2001年 | 56篇 |
2000年 | 50篇 |
1999年 | 45篇 |
1998年 | 21篇 |
1997年 | 8篇 |
1996年 | 16篇 |
1995年 | 22篇 |
1994年 | 29篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1982年 | 5篇 |
1980年 | 6篇 |
1978年 | 7篇 |
1975年 | 6篇 |
1974年 | 15篇 |
1973年 | 31篇 |
1972年 | 31篇 |
1971年 | 34篇 |
1970年 | 17篇 |
1969年 | 25篇 |
1968年 | 7篇 |
排序方式: 共有1624条查询结果,搜索用时 31 毫秒
51.
J. Allan Tucker 《Ultrastructural pathology》2013,37(6):383-389
For decades, transmission electron microscopy has played a valuable diagnostic role in surgical pathology. The continuing importance of electron microscopy, however, can be debated, given the major advances that have occurred in immunohistochemistry and other techniques. Electron microscopy retains excellent educational potential and broad research applicability, and it continues to be a necessity for the evaluation of a small subset of surgical pathology cases, such as renal biopsies and cilia specimens. The real controversy, then, centers on the contribution of electron microscopy in the evaluation of neoplasms. The opinion of many experts indicates that electron microscopy is still vital in the diagnostic assessment of some neoplasms, and that both electron microscopy and immunohistochemistry are more powerful when viewed as complementary rather than competitive techniques. For electron microscopy to be used to its potential, however, electron microscopists must function effectively as consultants. When optimally applied, electron microscopy remains an essential diagnostic tool. 相似文献
52.
John Hicks Andrew De Jong James Barrish Shen-Hua Zhu Edwina Popex 《Ultrastructural pathology》2013,37(1):79-83
Kniest dysplasia is an autosomal-dominant chondrodysplastic condition characterized by disproportionate dwarfism, short trunk, small pelvis, kyphoscoliosis, short limbs, prominent joints, premature osteoarthritis, and craniofacial manifestations. The craniofacial abnormalities include tracheomalacia, midface hypoplasia, cleft palate, early onset myopia, retinal detachment, prominent eyes, and sensorineural hearing loss. Radiologic features include dumbbell-shaped femora, platyspondylia with anterior wedging of vertebral bodies, coronal clefts of thoracolumbar vertebral bodies, low broad ilia, and short tubular bones with broad metaphyses and deformed large epiphyses. This form of chondrodysplasia is associated with mutations in type II collagen splicing sequences. Mutations have been identified in the COL2A1 (type II collagen) gene between exons 12 and 24. Type II collagen is the predominant structural protein in cartilage, and mutations in this collagen account for the Kniest dysplasia phenotype. Histopathologic and ultrastructural features of epiphyseal plate cartilage have been described, but tracheal cartilage in an affected neonate has not been examined. The authors report the histopathologic and ultrastructural findings of anterior tracheal cartilage from a 35-day-old female with suspected chondrodysplasia who had tracheomalacia with airway obstruction. The tracheal cartilage was moderately cellular, but lacked cystic and myxoid changes in its matrix. The chondrocytes had abundant cytoplasmic PAS-positive inclusions. Some of these inclusions were diastase-resistant and were also highlighted on Alcian blue staining. Ultrastructural examination revealed chondrocytes with greatly dilated rough endoplasmic reticulum containing granular proteinaceous material. There were also frequent aggregates of typical glycogen. The defect in the COL2A1 gene is secondary to mutations, especially at splice junctions, and this markedly disrupts triple helix formation. The mutated type II procollagen results in intracellular retention within the chondrocytes, as abundant granular proteinaceous material within the dilated RER. A relationship is known to exist between the proportion of mutated to normal type II collagen in the matrix and the severity of the phenotype. With low levels of normal type II collagen, the phenotypic manifestations become more severe, such as in achondrogenesis type II. Both the quantity and quality of type II collagen modulates the phenotypic expression of type II collagenopathies. 相似文献
53.
Since 1980 when Sibley and coworkers first described a nodal neoplasm of unknown histogenesis with striking surface microvilli for which they introduced the term "anemone cell," a series of reports have appeared in the literature illustrating tumors with similar ultrastructural features. While most reported cases showed differentiation along a particular line, rare cases remained histogenetically unclear. In this report a case is described of epithelioid gastric gastrointestinal stromal tumor metastatic to the liver, showing conspicuous long microvillus-type cell processes partially or circumferentially coating the cell surfaces, thus qualifying as yet another tumor type with anemone cell features. 相似文献
54.
The value of electron microscopy is demonstrated by ultrastructural identification of primary tumor site from bone metastases in 2 patients. 相似文献
55.
Electron microscopy plays a fundamental role in the evaluation of renal diseases in general. IgA nephropathy represents a heterogeneous disease clinically and morphologically. There are a number of conditions that need to be considered in the differential diagnosis of IgA nephropathy. The renal pathologist must wisely integrate the light microscopic, immunofluorescence, and ultrastructural data when evaluating cases in which IgA nephropathy is a consideration. Electron microscopy can be crucial in providing information either to support a diagnosis of IgA nephropathy or to aid in the diagnosis of one of its mimics. 相似文献
56.
Takuji Masunaga 《Connective tissue research》2013,54(2):55-66
The epidermal basement membrane is a specialized structure localized between the epidermis and the dermis. Recent studies have elucidated the biological roles of the basement membrane and its pathophysiological involvement in bullous diseases. To understand the functions of the basement membrane, it is essential to have clear and precise information regarding the ultrastructural molecular organization of the epidermal basement membrane. Immunoelectron microscopy is a powerful technique and the only method available for the clarification of the ultrastructural localization or orientation of molecules. This review summarizes the latest information regarding the molecular organization of the epidermal basement membrane as determined by immunoelectron microscopy as well as the blistering diseases that occur in the epidermal basement membrane zone. 相似文献
57.
ObjectiveThough the operating microscope (OM) has been the standard optical system in neurosurgery, a new technology called three-dimensional (3D) exoscope has emerged as an alternative. Herein, two types of 3D exoscopes for brain tumor surgery are presented. In addition, the advantages and limitations compared with the OM are discussed. MethodsIn the present study, 3D exoscope VOMS-100 or VITOM 3D was used in 11 patients with brain tumor who underwent surgical resection; the Kinevo 900 OM was used only in emergency. After completion of all surgeries, the participants were surveyed with a questionnaire regarding video image quality on the display monitor, handling of equipment, ergonomics, educational usefulness, 3D glasses, and expectation as a substitute for the OM. ResultsAmong 11 patients, nine patients underwent neurosurgical resection with only 3D exoscope; however, two patients required additional aid with the OM due to difficulty in hemostasis. Regarding video image quality, VITOM 3D was mostly equivalent to the OM, but VOMS-100 was not. However, both 3D exoscopes showed advantages in accessibility of instruments in the surgical field and occupied less space in the operating theater. Differences in ergonomics and educational usefulness between the exoscopes were not reported. Respondents did not experience discomfort in wearing 3D glasses and thought the exoscopes could be currently, and in the future, used as a substitute for the OM. ConclusionAlthough many neurosurgeons are not familiar with 3D exoscopes, they have advantages compared with the OM and similar image quality. Exoscopes could be a substitute for OM in the future if some limitations are overcome. 相似文献
58.
目的探讨显微镜辅助下颈前路椎间盘切除植骨融合术(anterior cervical discectomy with fusion,ACDF)治疗多节段脊髓型颈椎病的疗效。方法回顾性分析2011年1月~2012年8月本院行颈前路手术治疗的60例脊髓型颈椎病患者的临床资料,根据手术方式分为常规ACDF组(A组,30例)和显微镜辅助ACDF组(B组,30例)。比较2组的手术时间、术中出血量、住院天数及并发症,以日本骨科学会(Japanese Orthopaedic Association,JOA)评分(17分法)及其改善率评价术后神经功能改善情况。结果 A组手术时间为(132.5±8.9)min,B组为(137.0±9.1)min,差异无统计学意义(P0.05)。A组术中出血量为(113.6±8.0)m L,B组为(93.7±5.3)m L,差异有统计学意义(P0.01)。A组住院(7.37±1.73)d,B组(6.63±1.13)d,差异无统计学意义(P0.05)。A组术前JOA评分为6.60±1.21,术后12个月为13.83±0.91,改善率为(69.72±7.66)%;B组术前JOA评分为6.87±1.46,术后12个月为14.23±1.17,改善率为(72.51±11.26)%。A组和B组改善率差异有统计学意义(P0.05)。结论显微镜辅助ACDF和常规ACDF是治疗多节段脊髓型颈椎病有效的方法,但显微镜辅助ACDF可减少术中出血量,是治疗多节段脊髓型颈椎病优先选择的手术方案。 相似文献
59.
60.
目的 比较不同酸蚀时间处理后牙釉质表面的三维形貌并分析粗糙度的改变,探讨酸蚀对牙釉质微观形貌的影响.方法 将15颗新鲜前磨牙包埋、切割、打磨后得到光滑牙釉质切片,按单纯随机法分为5组,用37%磷酸凝胶分别酸蚀0(对照组)、5、10、20和30s,原子力显微镜观察釉质表面形貌,分析轮廓改变,计算图像的算术平均粗糙度(Ra)、均方根粗糙度(Rq)、十点高度平均差(Rz)值及表面积、容积并对5组的结果数据进行单因素方差分析,用Turkey's法进行组间两两比较,以P<0.05为差异有统计学意义.结果 镜下形貌观察显示,0~20 s内釉质的釉柱结构逐渐明显,釉质表面由较光滑逐渐变为典型鱼鳞状;20 s后表面形态变化不明显.表面轮廓观察显示,随着酸蚀时间由0s增加至30 s,釉柱间隙首先被溶解,酸蚀深度逐渐增加到2.8μm,30 s后釉柱顶部宽度减小至1.8μm,且高度略降低.从0s到30 s,Ra值由(19.69±3.42) nm增加到(359.51±75.79)nm,Rq值由(22.02±5.57) nm增加到(431.02±83.09) nm,Rz值由(0.24±0.08) μm增加到(2.38±0.26) μm;组间比较显示,Ra和Rq值的20s组与30 s组和Rz值的10、20和30 s组差异无统计学意义(P>0.05),其余各组间差异均有统计学意义(P<0.05).同时釉质表面积由(406.77±3.88) μm2 (0 s)增大到(546.69±84.02) μm2 (30 s),容积由(65.73±14.46) μm3 (0 s)增大到(474.63±52.50)μm3(30 s).结论 随着酸蚀时间的增加,釉质表面酸蚀深度不断增大,表面粗糙度增加,表面积及容积增大,酸蚀会造成釉质微观形貌的明显改变. 相似文献