全文获取类型
收费全文 | 104646篇 |
免费 | 8727篇 |
国内免费 | 6121篇 |
专业分类
耳鼻咽喉 | 1112篇 |
儿科学 | 1543篇 |
妇产科学 | 2305篇 |
基础医学 | 12403篇 |
口腔科学 | 1949篇 |
临床医学 | 14015篇 |
内科学 | 16579篇 |
皮肤病学 | 894篇 |
神经病学 | 5671篇 |
特种医学 | 3531篇 |
外国民族医学 | 42篇 |
外科学 | 11237篇 |
综合类 | 14801篇 |
现状与发展 | 23篇 |
一般理论 | 20篇 |
预防医学 | 6116篇 |
眼科学 | 2866篇 |
药学 | 10702篇 |
57篇 | |
中国医学 | 4825篇 |
肿瘤学 | 8803篇 |
出版年
2024年 | 281篇 |
2023年 | 1503篇 |
2022年 | 3803篇 |
2021年 | 4969篇 |
2020年 | 3514篇 |
2019年 | 3228篇 |
2018年 | 3544篇 |
2017年 | 2924篇 |
2016年 | 2844篇 |
2015年 | 4409篇 |
2014年 | 5619篇 |
2013年 | 5012篇 |
2012年 | 7523篇 |
2011年 | 8264篇 |
2010年 | 4976篇 |
2009年 | 3816篇 |
2008年 | 5268篇 |
2007年 | 5524篇 |
2006年 | 5405篇 |
2005年 | 5699篇 |
2004年 | 3831篇 |
2003年 | 3398篇 |
2002年 | 3005篇 |
2001年 | 2440篇 |
2000年 | 2650篇 |
1999年 | 2703篇 |
1998年 | 1579篇 |
1997年 | 1482篇 |
1996年 | 1308篇 |
1995年 | 1161篇 |
1994年 | 982篇 |
1993年 | 635篇 |
1992年 | 998篇 |
1991年 | 807篇 |
1990年 | 684篇 |
1989年 | 600篇 |
1988年 | 593篇 |
1987年 | 531篇 |
1986年 | 420篇 |
1985年 | 330篇 |
1984年 | 208篇 |
1983年 | 159篇 |
1982年 | 85篇 |
1981年 | 98篇 |
1980年 | 83篇 |
1979年 | 115篇 |
1978年 | 54篇 |
1977年 | 56篇 |
1975年 | 44篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Rong-Sen Yang Huei-Shien Chiang Chih-Hsin Tang Chia-Shin Yeh Tur-Fu Huang 《Toxicon》2005,46(4):387-393
Osteosarcoma is a very malignant bone tumor which has a high metastatic potential and usually lead to poor prognosis. The adhesion of tumor cells to the endothelium or extracellular matrix (ECM) is an essential step in the metastatic cascade. We investigated the effect of thrombin on the adhesion activity of the osteosarcoma cell line, ROS 17/2.8. Incubation with the low concentrations of thrombin (0.01-5 U/ml, 5 min to 24 h) elevated the adhesion activity of ROS 17/2.8 to both human umbilical vein endothelial cells (HUVEC) and extracellular matrix, with the peak effect at the concentration of 0.5 U/ml for 30 min at 37 degrees C. The ROS 17/2.8 cells responded to thrombin by a peak effect of increased adhesion to HUVEC (5.5 folds vs. control) and fibronectin (4.8 folds) after thrombin pretreatment (0.5 U/ml, 30 min, 37 degrees C). Pretreatment with monoclonal antibodies against beta3 integrins, including anti-alphavbeta3, 10E5 and 7E3, effectively antagonized the thrombin-enhanced cell adhesion activity, whereas anti-alpha3beta1 and anti-alpha5beta1 did not antagonize the enhanced cell adhesion. Rhodostomin, an Arg-Gly-Asp (RGD)-containing snake venom peptide, and synthetic peptide RGDS also blocked the thrombin-enhanced ROS 17/2.8 cell adhesion. This study demonstrated that thrombin enhanced the cell adhesion of ROS 17/2.8 cells to HUVEC or ECM through an upregulation of beta3 integrins, and rhodostomin was a strong inhibitor on thrombin-enhanced cell adhesion, either to HUVEC or fibronectin substratum. 相似文献
992.
993.
Shi-Long Zhong Shufeng Zhou Min Huang 《European journal of drug metabolism and pharmacokinetics》2005,30(3):181-185
OBJECTIVE: This study was to compare the frequencies of genetic polymorphisms of GSTM1, GSTT1, and GSTP1 in Uygur Chinese with those in Han Chinese. METHODS: GSTM1 and GSTT1 polymorphisms were analyzed by a PCR-Multiplex procedure, whereas GSTP1 polymorphism was analyzed by PCR-RFLP. RESULTS: The frequency of GSTM1 null genotype in Han Chinese (56.1%) was similar to that in Uygur Chinese (53.2%) (P = 0.592), whilst the frequency of GSTT1 null genotype in Han Chinese (50.0%) was significantly (P < 0.05) higher than that of Uygur Chinese (26.6%). GSTP1 had a genotype distribution of 60.7% I/I, 35.2% I/V and 4.1% V/V in Han Chinese, and 51.3% I/I, 40.2% I/V and 8.4% V/V in Uygur Chinese. CONCLUSION: There is marked ethnic difference in the mutant frequencies of GSTT1 and GSTP1, but not GSTM1, between Uygur and Han Chinese. 相似文献
994.
Association of serotonin 5-HT2A receptor binding and the T102C polymorphism in depressed and healthy Caucasian subjects. 总被引:4,自引:0,他引:4
Vadim D Khait Yung-yu Huang Gil Zalsman Maria A Oquendo David A Brent Jill M Harkavy-Friedman J John Mann 《Neuropsychopharmacology》2005,30(1):166-172
Serotonin 5-HT2A receptor (5-HT2A) binding is reported to be altered in individuals with suicidal behavior, mood disorders, and aggressive-impulsive traits. Genetic association with major depression, suicidal behavior, and aggressive-impulsive traits has not been established. This study examines the possible association of the 5-HT2A gene C102T polymorphism with the receptor binding kinetics, and clinical overt phenotypes. The study population included 63 healthy volunteers and 152 subjects with mood disorders, 56 of whom had a history of suicide attempts. All were Caucasian. Platelet 5-HT2A binding kinetics (Bmax and KD) were assayed and adjusted for seasonal variation. All subjects were genotyped for the T102C polymorphism. Clinical phenotype was determined by structured clinical interview. The TT genotype was associated with higher Bmax in all subjects (F=3.53, df=2,211; p=0.03), controlling for diagnosis. Bonferroni-adjusted post hoc testing showed higher binding in the TT compared with TC genotype in the control group (F=7.56, df=2,60, p=0.001), but not in the mood-disordered subjects. No difference was found in genotype and allele distribution between the mood-disordered subjects, with and without suicide attempt history, and controls. Bmax was not related to a diagnosis of mood disorders. The TT genotype appears associated with higher platelet 5-HT2A Bmax in the healthy population, but this genotypic effect appears absent in mood disorders and unrelated to psychopathology. 相似文献
995.
Zhu Li Mei Huang Junji Ichikawa Jin Dai Herbert Y Meltzer 《Neuropsychopharmacology》2005,30(11):1986-1995
The active moiety of clozapine, the prototypical antipsychotic drug, consists of clozapine and its major metabolite, N-desmethylclozapine (NDMC). Previous studies have suggested that NDMC may be more important than the patent compound itself for the improvement in cognition in patients with schizophrenia treated with clozapine. While the pharmacology of clozapine and NDMC are similar in most respects, NDMC has been shown to be an M1 muscarinic receptor partial agonist whereas clozapine is an M1 antagonist in vitro and in vivo. We hypothesized that NDMC may improve cognition by increasing dopamine (DA) and acetylcholine (ACh) release in medial prefrontal cortex (mPFC) via direct stimulation of M1 receptors, whereas both NDMC and clozapine itself would do so by other mechanisms as well, and that clozapine would inhibit the M1 agonist effect of NDMC. In the present study, using microdialysis in awake, freely moving rats, we found that NDMC at doses of 10 and 20, but not 5 mg/kg, significantly increased DA and ACh release in the mPFC and HIP, but not in the nucleus accumbens (NAC). The M1-preferring antagonist, telenzepine (3 mg/kg), completely blocked NDMC (10 mg/kg)-induced increases in cortical DA and ACh release. Clozapine (1.25 mg/kg), which by itself had no effect on DA or ACh release in the cortex, blocked NDMC (10 mg/kg)-induced ACh, but not DA, release in the mPFC. The 5-HT1A receptor antagonist, WAY100635 (0.2 mg/kg) blocked NDMC (20 mg/kg)-induced cortical DA but not ACh release. These findings suggest that: (1) NDMC is an M1 agonist while clozapine is an M1 antagonist in vivo; (2) M1 agonism of NDMC can contribute to the release of cortical ACh and DA release; (3) NDMC, because of its M1 agonism, may more effectively treat the cognitive impairments observed in schizophrenia than clozapine itself; and (4) M1 receptor agonism may be a valuable target for the development of drugs that can improve cognitive deficit in schizophrenia, and perhaps other neuropsychiatric disorders as well. 相似文献
996.
Dynamic contrast-enhanced subtraction and delayed MRI of gastric tumors: radiologic-pathologic correlation 总被引:12,自引:0,他引:12
PURPOSE: Our goal was to determine whether dynamic MR subtraction images could be used to detect and stage gastric tumors. METHOD: Dynamic MR subtraction images were prospectively performed in 20 patients without gastric lesions and in 39 patients with gastric tumors. The flat- or depressed-type early gastric cancers were excluded. The MR findings were assessed for layered pattern of the normal gastric wall, detectability of tumors, enhanced pattern of tumor, and depth of the tumor invasion. Surgical specimens were obtained from 30 of the patients with tumors, and histopathologic sections were made in the dynamic MR scanning direction. RESULTS: The three-layered structure of the normal gastric wall was apparent in more of the dynamic MR subtraction images (60%) than of the nonsubtraction images (30%) in the control group. All 39 gastric tumors were detected by MRI. The intact inner layers overlying stromal tumors and outer layers interrupted by advanced gastric cancers were clear on the subtracted images. MRI accurately T-staged 88% of the gastric cancers. CONCLUSION: Dynamic MR subtraction images can be used to identify gastric tumors and to stage gastric cancers. 相似文献
997.
复方魔芋葡甘聚糖对大鼠高脂血症的影响 总被引:3,自引:0,他引:3
目的:研究复方魔芋葡甘聚糖对大鼠高脂血症的影响.方法:建立高脂血症大鼠模型,将魔芋葡甘聚糖复配黄酮化合物,并喂饲大鼠,分别检测复方魔芋葡甘聚糖以及魔芋葡甘聚糖对大鼠血脂水平和肝脏组织形态的影响.结果:复方魔芋葡甘聚糖能显著降低大鼠血清总胆固醇的低密度脂蛋白-胆固醇(LDL-C)和载脂蛋白B(ApoB)浓度,显著增加高密度脂蛋白-胆固醇(HDL-C)和载脂蛋白A1(ApoAl)浓度,显著改善TG代谢,调节脂质代谢紊乱,降低血糖水平.肝组织形态学观察显示,复方魔芋葡甘聚糖对实验大鼠肝脏组织有保护作用.结论:复方魔芋葡甘聚糖能改善对实验大鼠高脂血症脂质代谢紊乱的调节作用. 相似文献
998.
为比较两种不同内固定方式在治疗髌骨粉碎性骨折中的临床疗效,将60例病人采用随机分组方法分成两组,分别采用镍钛记忆合金聚髌器(Niti-Patellar Concentrator NT-PC)(A组)和改良张力带钢丝内固定(B组)治疗,并对手术时间、术后骨折复位情况、骨折愈合时间、术后功能锻炼开始时间、膝关节屈曲达到90°的时间、手术后膝关节功能完全恢复时间及术后的并发症等结果进行比较.结果显示A组在手术时间、术后膝关节功能锻炼开始时间、膝关节屈曲达到90°和完全恢复的时间及骨折愈合的时间均早于B组,术后骨折复位比B组好(P<0.05),手术后无并发症.表明治疗髌骨粉碎性骨折NT-PC比改良张力带钢丝内固定有更广泛的适应症与更理想的效果. 相似文献
999.
1000.