全文获取类型
收费全文 | 54479篇 |
免费 | 5651篇 |
国内免费 | 3751篇 |
专业分类
耳鼻咽喉 | 472篇 |
儿科学 | 837篇 |
妇产科学 | 924篇 |
基础医学 | 5852篇 |
口腔科学 | 907篇 |
临床医学 | 6831篇 |
内科学 | 7996篇 |
皮肤病学 | 560篇 |
神经病学 | 2904篇 |
特种医学 | 1889篇 |
外国民族医学 | 32篇 |
外科学 | 6040篇 |
综合类 | 9452篇 |
现状与发展 | 11篇 |
一般理论 | 3篇 |
预防医学 | 4397篇 |
眼科学 | 1117篇 |
药学 | 5718篇 |
54篇 | |
中国医学 | 3367篇 |
肿瘤学 | 4518篇 |
出版年
2024年 | 252篇 |
2023年 | 1048篇 |
2022年 | 2455篇 |
2021年 | 3213篇 |
2020年 | 2403篇 |
2019年 | 1979篇 |
2018年 | 2054篇 |
2017年 | 2007篇 |
2016年 | 1771篇 |
2015年 | 2722篇 |
2014年 | 3222篇 |
2013年 | 3250篇 |
2012年 | 4467篇 |
2011年 | 4669篇 |
2010年 | 3035篇 |
2009年 | 2390篇 |
2008年 | 2939篇 |
2007年 | 2711篇 |
2006年 | 2565篇 |
2005年 | 2411篇 |
2004年 | 1678篇 |
2003年 | 1487篇 |
2002年 | 1363篇 |
2001年 | 1078篇 |
2000年 | 1016篇 |
1999年 | 1020篇 |
1998年 | 553篇 |
1997年 | 568篇 |
1996年 | 425篇 |
1995年 | 377篇 |
1994年 | 304篇 |
1993年 | 211篇 |
1992年 | 334篇 |
1991年 | 283篇 |
1990年 | 243篇 |
1989年 | 228篇 |
1988年 | 212篇 |
1987年 | 187篇 |
1986年 | 162篇 |
1985年 | 135篇 |
1984年 | 70篇 |
1983年 | 53篇 |
1982年 | 31篇 |
1981年 | 28篇 |
1980年 | 33篇 |
1979年 | 34篇 |
1978年 | 25篇 |
1974年 | 17篇 |
1971年 | 18篇 |
1970年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Sera from 130 first trimester pregnant women were tested for their serum antibody level against a naturally occurring serum antigen purified from non-pregnancy sera. IgG and IgM antibody level was measured using enzyme linked immunosorbant assay. Results indicate that patients with multiple abortion (n=26) have significantly (p=0.0029) lower level of IgG antibody and significantly (p=0.0001) higher level of IgM antibodies; against the serum antigen as compared to the patients with successful pregnancies with no history of miscarriage (n=63). Western blot analysis identified the scrum antigen recognized by the IgM antibody as a 24 kDa molecular mass component. These IgG and IgM antibodies may play an important role in the outcome of pregnancy. 相似文献
92.
93.
94.
It has been assumed that, when properly implanted, a biologically fixed device is less prone to loosening and probably to fatigue failure as well. This case demonstrates that many of the known risk factors of loosening or fatigue fracture of cemented tibial replacement devices must be considered when using devices designed for biologic fixation. Age, weight, axial alignment, and bone substrate have been identified as probable contributing factors to failure in the case reported here. Manufacturing technique and changes in material properties associated with porous coating should also be carefully tested for factors predisposing the components to fatigue failure. 相似文献
95.
Rupture of the tendon of the long head of the biceps brachii. Surgical versus nonsurgical treatment 总被引:2,自引:0,他引:2
E M Mariani R H Cofield L J Askew G P Li E Y Chao 《Clinical orthopaedics and related research》1988,(228):233-239
Twenty-seven shoulders (in 26 patients) that had surgical repair of a rupture of the long head of the biceps tendon between 1962 and 1981 were evaluated at three to 22 years after injury (mean, 13 years). Thirty similar patients had been treated nonsurgically and were evaluated two to 15 years (mean, 4.6 years) after tendon rupture. Biomechanical testing was performed on ten patients in the surgical group and 13 in the nonsurgical group. Residual arm pain was infrequent in both surgically and nonsurgically treated groups. Residual subjective weakness at the elbow was reported in four of the surgical group and in 20 of the nonsurgical group. Surgically treated patients returned to work later than nonsurgical patients; however, 11 in the nonsurgical group were not able to return to full work capacity, versus only two in the surgical group. On biomechanical testing, the nonsurgical group had lost a mean of 21% of supination strength and 8% of elbow flexion strength but had no weakness in grip, pronation, or elbow extension. The surgical group had lost no strength in any of these testing modes. 相似文献
96.
黄连细胞二步法悬浮培养生产黄连生物碱类成分的探索 总被引:6,自引:0,他引:6
为提高用植物细胞培养生产镒生代谢产物的单位产量,作者对黄连细胞采用二步法悬浮培养生产黄连生物碱进行了探索。结果显示:黄连细胞采用一步法悬浮培养6周,细胞干,鲜重产率分别为20.96g/L和174.92g/L,增重约700%,细胞中总生物碱含量为14.79mg/g.cell dw,培养基中生物碱量为12.96mg/L,每升培养液共可收获生物碱323mg。采用先在生长培养基中培养3周,在合成碱量为12 相似文献
97.
探讨荧光原位杂交法(FISH)对母血中胎儿有核红细胞(NRBC)进行无创性产前诊断的可行性。20例孕龄15-20周的孕妇外周血经不连续密度梯度离心、制片、显微镜下识别并共计数NRBC及定位,然后行Y染色体的FISH检测。结果发现10例孕男性胎儿的孕妇外周血细胞涂片中每例均有阳性杂交信号出现;阳性率为60%(24/40)。10例孕女性胎儿的孕妇外周血细胞涂片中1例出现阳性杂交信号;阴性率为95%(38/40),假阳性率仅为5%(2/40)。结果提示FISH法对于用母血中分离到的胎儿细胞进行染色体异常的无创性产前遗传学检查具有重要意义。 相似文献
98.
INAUGURAL ARTICLE by a Recently Elected Academy Member:The cell surface metalloprotease/disintegrin Kuzbanian
is required for axonal extension in Drosophila 下载免费PDF全文
Douglas Fambrough Duojia Pan GeraldM. Rubin CoreyS. Goodman 《Proceedings of the National Academy of Sciences of the United States of America》1996,93(23):13233-13238
It has long been suspected that proteolytic activity associated with advancing growth cones may be required for axon extension. We have isolated mutations in the kuzbanian (kuz) gene, which is expressed in the nervous system and encodes a putative zinc metalloprotease with a disintegrin domain. Drosophila embryos with loss-of-function mutations in kuz have dramatic defects in the development of central nervous system axon pathways, with many axons stalling and failing to extend through the nerve cord. This phenotype is rescued by panneural expression of kuz mRNA in the embryo. These results show that the Kuz metalloprotease is required for axon extension, suggesting a requirement for proteolytic activity at the growth cone surface. 相似文献
99.
目的探讨微创手术在食管平滑肌瘤治疗中的临床应用价值. 方法回顾性分析1996年9月~2002年10月26例食管平滑肌瘤采用微创手术治疗的临床资料. 结果电视胸腔镜食管平滑肌瘤摘除术23例,其中3例(2例胸膜腔紧密粘连,1例肿瘤无法定位)中转开胸(胸腔镜辅助小切口);经颈部食管平滑肌瘤摘除术2例;经食管镜食管平滑肌瘤切除1例.26例手术顺利,术后恢复平稳,无手术死亡及严重并发症,术后病理诊断均为平滑肌瘤.随访2~73个月,平均32.3个月,无复发. 结论电视胸腔镜肌瘤摘除术可作为食管固有肌层平滑肌瘤的首选治疗方法,对于食管粘膜肌层的平滑肌瘤,可考虑经食管镜切除. 相似文献
100.
环氧合酶-2及其选择性抑制剂塞来昔布对结肠癌肝转移瘤VEGF、FGF-2影响的实验研究 总被引:2,自引:0,他引:2
目的 :研究环氧化酶 2及其选择性抑制剂塞来昔布和血管生成因子VEGF、FGF 2间的关系 ,从而探讨环氧化酶 2对结肠癌肝转移瘤血管形成的影响。方法 :以细胞培养法建立稳定的结肠癌细胞株HT 2 9和HCT 116 ,利用脾切除法建立结肠癌肝转移动物模型 ,免疫组化检测结肠癌肝转移瘤VEGF、FGF 2蛋白表达。结果 :结肠癌肝脏转移率 ,HT 2 9组、HCT 116组、塞来昔布组分别为 83 33%、16 6 7%、33 33%。肝脏转移瘤VEGF、FGF 2的表达 ,HT 2 9组与HCT 116组、塞来昔布组比较均表达增强 ,有显著统计学意义 (P <0 0 1~ 0 0 5 ) ;塞来昔布组与HCT 116组比较无显著性差异 (P >0 0 5 )。结论 :环氧合酶 2与结肠癌肝转移瘤血管生成密切相关 ,其高表达促进了结肠癌肝转移瘤新生血管生成。其机制可能是上调促血管生成因子VEGF、FGF 2的表达 相似文献