全文获取类型
收费全文 | 166733篇 |
免费 | 16355篇 |
国内免费 | 9900篇 |
专业分类
耳鼻咽喉 | 1282篇 |
儿科学 | 2227篇 |
妇产科学 | 1658篇 |
基础医学 | 22779篇 |
口腔科学 | 2850篇 |
临床医学 | 19928篇 |
内科学 | 22156篇 |
皮肤病学 | 1759篇 |
神经病学 | 7553篇 |
特种医学 | 5777篇 |
外国民族医学 | 65篇 |
外科学 | 15567篇 |
综合类 | 30293篇 |
现状与发展 | 33篇 |
一般理论 | 12篇 |
预防医学 | 13030篇 |
眼科学 | 3688篇 |
药学 | 19199篇 |
161篇 | |
中国医学 | 10461篇 |
肿瘤学 | 12510篇 |
出版年
2024年 | 723篇 |
2023年 | 2594篇 |
2022年 | 6537篇 |
2021年 | 8264篇 |
2020年 | 6206篇 |
2019年 | 5242篇 |
2018年 | 5479篇 |
2017年 | 5215篇 |
2016年 | 4863篇 |
2015年 | 7264篇 |
2014年 | 9086篇 |
2013年 | 9107篇 |
2012年 | 12900篇 |
2011年 | 13541篇 |
2010年 | 9970篇 |
2009年 | 8249篇 |
2008年 | 9560篇 |
2007年 | 9520篇 |
2006年 | 8605篇 |
2005年 | 7516篇 |
2004年 | 5766篇 |
2003年 | 5478篇 |
2002年 | 4617篇 |
2001年 | 3861篇 |
2000年 | 3249篇 |
1999年 | 2721篇 |
1998年 | 1682篇 |
1997年 | 1803篇 |
1996年 | 1268篇 |
1995年 | 1203篇 |
1994年 | 1094篇 |
1993年 | 767篇 |
1992年 | 972篇 |
1991年 | 888篇 |
1990年 | 791篇 |
1989年 | 731篇 |
1988年 | 651篇 |
1987年 | 566篇 |
1986年 | 535篇 |
1985年 | 425篇 |
1984年 | 371篇 |
1983年 | 302篇 |
1982年 | 268篇 |
1981年 | 229篇 |
1980年 | 196篇 |
1979年 | 198篇 |
1978年 | 192篇 |
1977年 | 211篇 |
1976年 | 191篇 |
1974年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
981.
982.
BACKGROUND: Impaired implantation in assisted reproduction cycles with high serum estradiol (E(2)) concentrations may be related to suboptimal endometrial perfusion. Endometrial and subendometrial blood flow were compared between excessive responders (serum E(2) on the day of HCG >20 000 pmol/l) and moderate responders (E(2) < or =20 000 pmol/l). METHODS: Three-dimensional (3D) ultrasound examination with power Doppler was performed 2, 4 and 7 days after HCG in 32 patients who did not have embryo transfer in order to measure endometrial thickness, pulsatility index (PI)/resistance index (RI) of uterine vessels, and endometrial volume, vascularization index (VI)/flow index (FI)/vascularization flow index (VFI) of endometrial and subendometrial regions. RESULTS: Excessive responders tended to have lower endometrial and subendometrial VI/VFI on HCG +2 and more absent endometrial/subendometrial blood flow. They had significantly higher endometrial FI and subendometrial VFI than moderate responders on HCG +7. Only in the excessive responder group, uterine PI/RI declined significantly from HCG +2 to HCG +7 and endometrial VI/VFI increased significantly from HCG +4 to HCG +7. CONCLUSION: Changes in uterine Doppler flow indices, and endometrial and subendometrial 3D power Doppler flow indices during the early luteal phase were significantly different between moderate and excessive responders. 相似文献
983.
目的 :研究突变型p2 7基因 (p2 7mt)对肝癌细胞生长的影响。方法 :采用重组腺病毒载体Ad p2 7mt将p2 7mt全长cDNA转入到肝癌细胞系SMMC 772 1中。3H TdR掺入法及软琼脂集落形成实验检测p2 7mt对肝癌细胞增殖的作用。结果 :转染p2 7mt基因的SMMC 772 1细胞在蛋白质水平有高水平的基因表达。其3H TdR掺入量及集落形成率明显低于对照组 (P <0 .0 5)。结论 :p2 7mt基因能抑制肝癌细胞增殖。p2 7mt可作为目的基因用于基因治疗。 相似文献
984.
目的为下丘脑室旁核参与惊厥应答提供形态学资料。方法:以听源性忭厥易大鼠为动物模型,用免疫组织化学ABC法显示下丘脑室旁核神经元即早基因c-fos的表达。 相似文献
985.
紫香驱蚴灵是预防日本血吸虫尾蚴感染的新型皮肤外用药。经毒性试验研究证实,大鼠口服LD50为2636(2207—3148)mg/kg,皮肤给药的LD50>5325mg/kg。家兔皮肤敷药部位未见红斑和水肿,豚鼠皮肤过敏试验,未见过敏反应,表明紫香驱蚴灵属低毒类、无刺激性、弱致敏性物质,局部皮肤外用是较安全的 相似文献
986.
P. V. Sergeev S. A. Chukaev Yu. A. Korovkina 《Bulletin of experimental biology and medicine》1997,124(2):786-788
Effects of estradiol and testosterone and of the antiandrogens cyproterone acetate, niftolide, and antiestrogen tamoxifen
on the activities of human erythrocyte glutathione peroxidase and glutathione reductase were studiedin vitro. In contrast to hormone preperations, antihormones in high concentrations (10−4−5×10−4 M) modified the enzyme activities. Cyproterone acetate and tamoxifen increased the activity of glutathione reductase, while
tamoxifen stimulated glutathione reductase and inhibited glutathione peroxidase. Niftolide inhibited both enzymes.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 8, pp. 185–187, August, 1997 相似文献
987.
Antibody against fusarochromanone (TDP‐1) was obtained from rabbits after immunization with TDP‐1 conjugated to bovine serum albumin (BSA). An indirect enzyme‐linked immunosorbent assay (ELISA) using TDP‐1‐ovalbumin conjugate as the antigen coated on to the microtiter plate was used for monitoring the antibody liter. For toxin detection, a direct competitive ELISA in which TDP‐1 was conjugated to horseradish peroxidase (HRP) was used. Competitive direct ELISA revealed that the antibody had about 5.6 and 4.5 times greater binding efficiency for monoacetyl fusarochromanone (TDP‐2) and diacetylated TDP‐1 than TDP‐1. The concentration causing 50% inhibition of binding of TDP‐1‐HRP to the antibody by TDP‐1, TDP‐2 and diacetyl‐TDP‐1 were 2.8, 0.5 and 0.62 ng/ml, respectively. For the analysis of fusarochromanones in wheat and barley, the toxins were first extracted from the commodities with 100% methanol. A small aliquot of the extract was dried, acetylated, diluted in buffer and then analyzed directly by ELISA. The overall recovery for fusarochromanone in the wheat and barley samples spiked with TDP‐1 in the concentration range of 20 to 500 ppb were found to be 97% and 103.4% with cv of 15% and 11.2% for barley and wheat, respectively. 相似文献
988.
Ruthenium red has been shown to have a positive inotropic effect on isolated perfused hearts. The cellular mechanism of this action is not clear. Ruthenium red is able to block the Ca2+ release channel in isolated sarcoplasmic reticulum (SR) vesicle and reconstituted channel preparations. However, the effect of ruthenium red on SR Ca2+ release has not been studied in skinned cardiac muscle preparations. In the present study we investigated the actions of ruthenium red on both the characteristics of force generation by the contractile apparatus and Ca2+ release from the SR in chemically skinned rat papillary muscle. Ruthenium red (2 and 10 M) significantly increased the Ca2+ sensitivity of the contractile apparatus (decreasing Ca2+ required for the half-maximal response from 1.56±0.04 M to 1.46±0.05 M) but had no effect on the maximal Ca2+-activated force in triton X-100 treated fibers. This result may suggest one explanation for the positive inotropic effect of ruthenium red on the heart. On the other hand, ruthenium red had no significant effect on either caffeine-induced Ca2+ release or Ca2+-induced Ca2+ release from the SR in saponin-skinned muscle fibers. Lack of a blocking effect on SR Ca2+ release by ruthenium red in skinned fibers suggests that the SR Ca2+ channels in intact preparations have characteristics that are different from those of either vesicular or reconstituted channel preparations. 相似文献
989.
990.
B. S. Gusman Yu. V. Vul'fovich G. Ya. Kagan 《Bulletin of experimental biology and medicine》1975,80(3):1120-1123
A histological and histochemical study was made of the internal organs of albino mice at various times (from 24 h to 27 weeks) after a single intraperitoneal injection of L-forms of -hemolytic group A streptococci. A progressive pathological process (myocarditis, hepatitis, glomerulonephritis) against a marked allergic bacground and leading to systemic lesions of the tissues was discovered.Institute of Human Morphology, Academy of Medical Sciences of the USSR. N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byullten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 9, pp. 111–115, September, 1975. 相似文献