全文获取类型
收费全文 | 227250篇 |
免费 | 57000篇 |
国内免费 | 9679篇 |
专业分类
耳鼻咽喉 | 2881篇 |
儿科学 | 6490篇 |
妇产科学 | 2968篇 |
基础医学 | 33866篇 |
口腔科学 | 7597篇 |
临床医学 | 31894篇 |
内科学 | 45686篇 |
皮肤病学 | 9134篇 |
神经病学 | 20667篇 |
特种医学 | 8264篇 |
外国民族医学 | 92篇 |
外科学 | 30538篇 |
综合类 | 22590篇 |
现状与发展 | 37篇 |
一般理论 | 61篇 |
预防医学 | 14470篇 |
眼科学 | 5957篇 |
药学 | 21582篇 |
130篇 | |
中国医学 | 8958篇 |
肿瘤学 | 20067篇 |
出版年
2024年 | 492篇 |
2023年 | 2274篇 |
2022年 | 5763篇 |
2021年 | 8803篇 |
2020年 | 10342篇 |
2019年 | 15373篇 |
2018年 | 15173篇 |
2017年 | 15701篇 |
2016年 | 16269篇 |
2015年 | 18223篇 |
2014年 | 19801篇 |
2013年 | 19685篇 |
2012年 | 15459篇 |
2011年 | 16199篇 |
2010年 | 16383篇 |
2009年 | 11187篇 |
2008年 | 10306篇 |
2007年 | 9098篇 |
2006年 | 9027篇 |
2005年 | 8349篇 |
2004年 | 6322篇 |
2003年 | 5891篇 |
2002年 | 5271篇 |
2001年 | 4658篇 |
2000年 | 4380篇 |
1999年 | 4056篇 |
1998年 | 2261篇 |
1997年 | 2230篇 |
1996年 | 1734篇 |
1995年 | 1546篇 |
1994年 | 1357篇 |
1993年 | 893篇 |
1992年 | 1297篇 |
1991年 | 1083篇 |
1990年 | 998篇 |
1989年 | 892篇 |
1988年 | 790篇 |
1987年 | 667篇 |
1986年 | 573篇 |
1985年 | 485篇 |
1984年 | 348篇 |
1983年 | 234篇 |
1982年 | 160篇 |
1981年 | 191篇 |
1980年 | 115篇 |
1979年 | 232篇 |
1978年 | 116篇 |
1974年 | 119篇 |
1973年 | 123篇 |
1972年 | 109篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
多层螺旋CT与选择性冠状动脉造影对照研究及其临床应用 总被引:50,自引:2,他引:48
目的 评价冠状动脉多层螺旋CT血管造影(MSCTA)的临床应用价值。方法 25例患者均行冠状动脉MSCTA与选择性冠状动脉造影(SCA),分析右冠状动脉、左冠状动脉主干、前降支和回旋支的通畅性,狭窄发生的部位和严重程度。将MSCTA与SCA结果对照,初步评价MSCTA的临床应用价值。结果 71支MSCTA显示无狭窄的冠状动脉支中,68支与SCA一致;29支显示狭窄的动脉支中,19支与SCA一致。其阴性预测值和阳性预测值分别为95.8%和65.5%;敏感度、特异度和准确度分别为86.4%、87.2%、87,0%。结论 MSCTA作为微创性检查,是评价冠状动脉病变和变异的重要的筛选手段。 相似文献
992.
凝血因子Ⅷ(FⅧ)由vWF和FⅧ:C组成。FⅧ:C的合成部位至今尚未确认。本文检测了16~22周胎龄胎儿肝、脾、肾及肾小球组织中Ⅷ:C活性及vWF:Ag含量后,发现肾中Ⅷ:C活性较高(1.679±1.588 U/ml),尤其是肾小球中高达46.313±40.651U/ml,脾中次之(0.372±0.462 U/ml),肝中最低(0.021±0.029U/ml)。将3种组织细胞培养后,发现仍以肾中Ⅷ:C活性最高。由此提示,肾可能是Ⅷ:C的合成部位。同时检测三器官中vWF:Ag,发现含量极微。这些组织中Ⅷ:C与vWF的关系有待研究。 相似文献
993.
本文对山药及其混伪品的基源、性状、显微和理化鉴别特征进行了比较,阐述了作者的鉴别体会,并编制了显微鉴别特征检索在,可供临床、教学、鉴定等工作参考。 相似文献
994.
用间接免疫荧光法检测了延边地区14岁以下不同年龄组的正常人群血清中抗B19病毒抗体。结果如下:抗体阳性率为12.9%,各年龄组抗体阳性率分布不均,主要在7.5%~22.5%之间,几何平均效价为1:19,各年龄组的几何平均效价在1:16~1:25之间;抗体效价分布在1:10~1:80之间,主要在1:40以下,朝鲜族和汉族的病毒抗体阳性率分别为9.7%和16.0%,几何平均效价分别为1:21和1:18.统计结果表明,各年龄组之间及朝鲜族和汉族之间,抗体阳性率和几何平均效价均无显著性差异(P>0.05). 相似文献
995.
用化学发光法检测粒细胞吞噬功能具有灵敏、准确、快速等优点。用我校同位素实验室LS3801型液体闪烁分析仪,全部使用国产试剂,建立了分离的中性粒细胞化学发光测定法,并对影响因素作了初步观察和探讨。实验表明,此法既可用于中性粒细胞吞噬杀菌功能机理研究,亦可用于临床监测。对糖尿病人粒细胞功能化学发光测定结果,显示了此法应用的潜力。 相似文献
996.
本实验采用随机引物法标记探针DNA.探针DNA加热变性成单链,以单链DNA为模板,六聚脱氧核苷酸为引物,在DNA多聚酶I大片段的作用下进行放射性标记.标记探针的比放射性达10~8cpm/μg DNA以上.放射性底物的掺入率为60%.用该方法标记的人高度重复顺序探针,可以检出微微克水平的阳性分子.与人HeLa S_3细胞DNA转化的小鼠LTK~+细胞DNA打点杂交呈阳性,与未经转化的小鼠LTK~-细胞DNA杂交为阴性,证明小鼠转化细胞中存在HeLa细胞DNA,DNA转化是成功的. 相似文献
997.
H M Lazarus L T Goodnough E Goldwasser G Long J L Arnold K P Strohl 《Bone marrow transplantation》1992,10(1):71-75
To determine the potential impact of recombinant human erythropoietin (EPO) therapy in patients undergoing autologous bone marrow transplantation (BMT) and colony-stimulating factor therapy, we assayed endogenous serum EPO levels and noted blood transfusion requirements in relapsed non-Hodgkin's lymphoma patients treated with high-dose chemo-radiation therapy and autologous BMT. Hematocrit and reticulocyte counts were determined daily, and hematocrit was maintained in the 25-30% range by transfusion according to criteria established by our hospital transfusion committee. EPO levels were measured by radioimmunoassay and were determined at baseline, throughout therapy, and 2 and 3 months after BMT. Serum EPO levels increased more than 25-fold above baseline in most subjects after initiating chemoradiation therapy. No correlation was noted between serum EPO and hematocrit, reticulocyte count or serum creatinine. Total red blood cell units transfused ranged from 4 to 15 (mean 7.7). Mean total donor exposures (red blood cell plus platelet units transfused) were 83.6 units (range 16-175). Serum EPO levels increased early in the course of preparation for autologous BMT and remained elevated for at least 2-3 weeks thereafter although at a lower level. Red blood cell transfusions were required despite very high EPO levels after BMT. Red cell transfusions, moreover, accounted for only 9.2% (69 of 746) of total donor exposures and only 5.8% (42 of 746) of donor exposures during the interval when pharmacologic doses of erythropoietin might be of benefit. In contrast to the potential benefit of colony-stimulating factors such as G-CSF and GM-CSF in BMT, our study suggests limited value for erythropoietin therapy in this setting. 相似文献
998.
Dog pancreatic islets isolated by an enzymatic digestion method were encapsulated in an alginate-poly L-lysine-alginate membrane. These microencapsulated pancreatic islets were cultured in vitro to study their ability of insulin secretion. Portions of these in vitro-cultured microencapsulated pancreatic islets were taken out for a viability dye exclusion study as well as for pathologic studies to correlate them with insulin secretion ability. We found that there was a strong correlation between them. Good insulin-secreting microcapsules showed well-preserved cell membranes and beta-cell granules. An in vitro culture for one to two days in RPMI-1640 made the islets more stable, the cellular surface became smoother and the beta-granules were in better shape. The microencapsulated pancreatic islets were also injected into the peritoneum of streptozotocin-induced diabetic CDF1 mice. Blood glucose levels dropped and stayed low for up to 60 days. But, when non-encapsulated dog pancreatic islets were used, the blood glucose levels remained low for only about 14 days. A small portion of the injected microcapsules were washed out at specific times for pathologic study. Up to 28 days after injection, only a few of the injected microcapsules showed pericapsular cellular infiltrate. However, after 56 days, most of the microcapsules showed dense pericapsular cellular infiltrate. Immunohistochemical analysis of these infiltrates showed that the majority of cells were fibroblasts and macrophages. Most of the cells located in the inner portion of the infiltrate were fibroblasts, while the macrophages were located mainly on the outer portion. Both scanning and transmission electron microscopy showed that the surface of the microcapsule outer wall was much smoother than the inner wall. The size of the microcapsules was approximately 0.6-0.8 mm and the thickness of the wall measured around 10 nm. The smaller the microcapsule is, the less chance there is of rupture with release of the xenographic islets. Once the wall of the transplanted microcapsules was ruptured, the inner surface showed more increased inflammatory cell and fibroblast infiltration than the outer surface. 相似文献
999.
1000.
Five compounds have been isolated from the stems and leaves of Isodon albopilosus. On the basis of spectroscopic and chemical data, they were identified as macrocalyxin C, stearic acid, beta-sitosterol, ursolic acid and beta-sitosterol-beta-D-glucoside, respectively. 相似文献