全文获取类型
收费全文 | 230412篇 |
免费 | 16538篇 |
国内免费 | 5632篇 |
专业分类
耳鼻咽喉 | 3016篇 |
儿科学 | 3894篇 |
妇产科学 | 4439篇 |
基础医学 | 32107篇 |
口腔科学 | 4664篇 |
临床医学 | 23176篇 |
内科学 | 40193篇 |
皮肤病学 | 5334篇 |
神经病学 | 15396篇 |
特种医学 | 11031篇 |
外国民族医学 | 21篇 |
外科学 | 28789篇 |
综合类 | 14186篇 |
现状与发展 | 32篇 |
一般理论 | 85篇 |
预防医学 | 14859篇 |
眼科学 | 6459篇 |
药学 | 21247篇 |
67篇 | |
中国医学 | 5369篇 |
肿瘤学 | 18218篇 |
出版年
2023年 | 1898篇 |
2022年 | 4947篇 |
2021年 | 7800篇 |
2020年 | 4730篇 |
2019年 | 5570篇 |
2018年 | 6518篇 |
2017年 | 5257篇 |
2016年 | 6180篇 |
2015年 | 8637篇 |
2014年 | 10772篇 |
2013年 | 12100篇 |
2012年 | 18160篇 |
2011年 | 18246篇 |
2010年 | 11240篇 |
2009年 | 9568篇 |
2008年 | 13603篇 |
2007年 | 13172篇 |
2006年 | 12302篇 |
2005年 | 11487篇 |
2004年 | 9762篇 |
2003年 | 8942篇 |
2002年 | 7661篇 |
2001年 | 6036篇 |
2000年 | 5406篇 |
1999年 | 4490篇 |
1998年 | 2091篇 |
1997年 | 1677篇 |
1996年 | 1554篇 |
1995年 | 1391篇 |
1994年 | 1268篇 |
1993年 | 986篇 |
1992年 | 1945篇 |
1991年 | 1919篇 |
1990年 | 1643篇 |
1989年 | 1505篇 |
1988年 | 1332篇 |
1987年 | 1220篇 |
1986年 | 1154篇 |
1985年 | 977篇 |
1984年 | 699篇 |
1983年 | 603篇 |
1982年 | 440篇 |
1981年 | 408篇 |
1980年 | 369篇 |
1979年 | 537篇 |
1978年 | 415篇 |
1977年 | 391篇 |
1976年 | 347篇 |
1974年 | 366篇 |
1973年 | 338篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
原发性肝癌患者肝切除术前、后免疫细胞表型分析 总被引:1,自引:1,他引:0
目的研究原发性肝癌(PrimaryLiverCarcinoma,PLC)患者肝切除术前、后免疫细胞表型的变化。方法采用直接免疫荧光标记,流量血细胞计数法(FlowCytometry,FCM)检测方法,动态观察120例PLC患者肝切除术前后外周血T淋巴细胞亚群、NK细胞和HLA鄄DR含量变化。结果肝切除术前肝功能Child鄄PughB级、OGTTL型和术前施行肝动脉栓塞化疗患者外周血CD8+T细胞含量明显低于正常人组,CD4+/CD8+比值则较高(P<0郾05)。全部肝癌患者肝切除术前、后CD3+CD4+T细胞和NK细胞(CD3-CD16+CD56+)含量无明显差异。术后第1天、第3天、第7天和第2周外周血淋巴细胞CD3+CD8+含量明显低于肝切除术前和术后第3周(P<0.01);而CD4+/CD8+比值则显著高于肝切除术前和术后第3周(P<0郾01)。结论PLC合并肝硬变肝储备功能不足、术前肝动脉栓塞化疗和肝切除术可导致机体细胞免疫功能低下,PLC患者肝切除术前行肝动脉栓塞化疗的价值有待深入研究。 相似文献
72.
73.
Luis Hernandez-Garcia Gregory R Lee Alberto L Vazquez Chun-Yu Yip Douglas C Noll 《Magnetic resonance in medicine》2005,54(4):955-964
A new approach to modeling the signal observed in arterial spin labeling (ASL) experiments during changing perfusion conditions is presented in this article. The new model uses numerical methods to extend first-order kinetic principles to include the changes in arrival time of the arterial tag that occur during neuronal activation. Estimation of the perfusion function from the ASL signal using this model is also demonstrated. The estimation algorithm uses a roughness penalty as well as prior information. The approach is demonstrated in numerical simulations and human experiments. The approach presented here is particularly suitable for fast ASL acquisition schemes, such as turbo continuous ASL (Turbo-CASL), which allows subtraction pairs to be acquired in less than 3 s but is sensitive to arrival time changes. This modeling approach can also be extended to other acquisition schemes. 相似文献
74.
As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 ± 0.3 vs. 2.2 ± 0.3 cps) and human semen (5.0 ± 0.3 vs. 4.3 ± 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 ± 0.7 vs. 96.8 ± 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 ± 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen. 相似文献
75.
76.
Though distressing and potentially dangerous, sleep apnea may be an under-recognized disease in many countries. The obstructive type, which usually presents with loud snoring and excessive daytime sleepiness, is by far the commonest form. It causes a great deal of medical, social and psychological morbidity as well as an increased mortality. Doctors of different specialties have an important role in detecting and referring suspected patients for early assessment and treatment. Multidisciplinary management in a general hospital and accurate assessment with polysomnography are essential as modern and sometimes effective methods of treatment are becoming available. 相似文献
77.
78.
79.
80.
David K.H. Lee 《Drug development research》1986,9(4):305-311
The effect of acute and subchronic dosing with etodolac on the renal PGE2 and 6-keto-PGF1α concentrations in the normal rat were studied. Etodolac and other nonsteroidal antiinflammatory drugs (NSAIDs) were administered orally, at equieffective antiinflammatory doses, to normal rats either as a single dose or as seven daily doses. Whole kidney prostaglandin (PG) concentrations were measured. In the acute study, etodolac (3 mg/kg) did not significantly lower the PGE2 levels for up to 4 hr postdosing. In contrast, naproxen (3 mg/kg) and piroxicam (0.5 mg/kg) significantly decreased the PGE2 levels to about 20% and 60% of control, respectively. Similar reductions in 6-keto-PGF1α concentrations were observed. In the subchronic study, etodolac (3 mg/kg/day) did not lower either PGF2 or 6-keto-PGF1α concentrations whereas naproxen (3 mg/kg/day), piroxicam (0.5 mg/kg/day), indomethacin (1 mg/kg/day), and aspirin (300 mg/kg/day) significantlydecreased both PGs. In both studies, the effect of etodolac was significantly different from that of the NSAIDs. It is concluded that etodolac possesses only a very weak capacity to lower renal PGs, and therefore is unlikely to cause any renal complications related to PG biosynthesis inhibition. 相似文献