全文获取类型
收费全文 | 145525篇 |
免费 | 13529篇 |
国内免费 | 10875篇 |
专业分类
耳鼻咽喉 | 1144篇 |
儿科学 | 1582篇 |
妇产科学 | 1992篇 |
基础医学 | 17836篇 |
口腔科学 | 2497篇 |
临床医学 | 20122篇 |
内科学 | 21803篇 |
皮肤病学 | 1376篇 |
神经病学 | 8608篇 |
特种医学 | 5263篇 |
外国民族医学 | 102篇 |
外科学 | 13904篇 |
综合类 | 22785篇 |
现状与发展 | 40篇 |
一般理论 | 16篇 |
预防医学 | 9593篇 |
眼科学 | 4486篇 |
药学 | 15154篇 |
160篇 | |
中国医学 | 8598篇 |
肿瘤学 | 12868篇 |
出版年
2024年 | 468篇 |
2023年 | 2345篇 |
2022年 | 6324篇 |
2021年 | 7889篇 |
2020年 | 5861篇 |
2019年 | 5114篇 |
2018年 | 5414篇 |
2017年 | 4565篇 |
2016年 | 4507篇 |
2015年 | 6693篇 |
2014年 | 8274篇 |
2013年 | 7012篇 |
2012年 | 10593篇 |
2011年 | 12052篇 |
2010年 | 7284篇 |
2009年 | 5668篇 |
2008年 | 7454篇 |
2007年 | 7429篇 |
2006年 | 7589篇 |
2005年 | 7601篇 |
2004年 | 4781篇 |
2003年 | 4649篇 |
2002年 | 3929篇 |
2001年 | 3146篇 |
2000年 | 3320篇 |
1999年 | 3519篇 |
1998年 | 2332篇 |
1997年 | 2206篇 |
1996年 | 1734篇 |
1995年 | 1609篇 |
1994年 | 1315篇 |
1993年 | 851篇 |
1992年 | 1003篇 |
1991年 | 866篇 |
1990年 | 781篇 |
1989年 | 697篇 |
1988年 | 634篇 |
1987年 | 527篇 |
1986年 | 457篇 |
1985年 | 360篇 |
1984年 | 206篇 |
1983年 | 148篇 |
1982年 | 94篇 |
1981年 | 87篇 |
1980年 | 64篇 |
1979年 | 118篇 |
1978年 | 41篇 |
1975年 | 40篇 |
1974年 | 52篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
J Zhao 《中华神经精神科杂志》1991,24(3):138-40, 186-7
18 patients with acute cerebral infarction were randomly subdivided into two groups: PGI2-treated group (11 cases) and low-molecular-weight Dextran-treated group (7 cases). Dosage of PGI2 was 2-5 ng/kg/min intravenous drip. Infusion was started within 72 hours after the onset of symptoms. The data showed that the plasma 6-keto-PGF1 alpha levels were increased, the plasma TXB2 levels, MAR as well as the scores of neurological deficit were decreased in the PGI2-treated group. The clinical improvement in PGI2-treated group is better than that in the dextran-treated group. 相似文献
12.
13.
14.
Lei Wang Moyi Sun Yuegui Jiang Lianjia Yang Delin Lei Chao Lu Yinghua Zhao Pu Zhang Yaowu Yang Jianhu Li 《Journal of oral and maxillofacial surgery》2006,64(4):636-641
PURPOSE: Perineural invasion is a frequent occurrence in salivary adenoid cystic carcinoma (ACC) and may prevent complete surgical resection. Studies have indicated that nerve growth factor (NGF) and its high-affinity receptor tyrosine kinase A (TrkA) may play a role in perineural invasion in several malignancies in which perineural invasion is observed. The present study was conducted to investigate the expression of NGF and TrkA in salivary ACC and to examine the effects of NGF on adhesion, migration and invasion capacities of a salivary ACC cell line (SACC-83) in vitro. PATIENTS AND METHODS: Expression of NGF and TrkA was explored using immunohistochemistry in paraffin-embedded tissues of 32 cases of salivary ACC. The effects of NGF on in vitro adhesion, migration, and invasion capacities of the SACC-83 cell line were examined using an MTT assay and a modified Boyden chamber assay respectively. RESULTS: In ACC specimens, 31 (96.9%) and 32 (100%) tumors showed immunoreactivity for NGF and TrkA respectively. Significant correlations were found between NGF/TrkA expression levels and perineural invasion (P < .05). In cell adhesion assay, the percent adherences of SACC-83 cells co-cultured with 25 ng/ml NGF at 1.5 hours and 5, 25 ng/ml NGF at 6 hours were significantly higher than that co-cultured with 0 ng/ml NGF (P < .05). However, high concentration of NGF (500 ng/ml) resulted in a significant inhibition of invasion (P < .05). CONCLUSION: Overexpression of NGF and TrkA in human salivary ACC tissues may constitute a reason for perineural invasion in salivary ACC. 相似文献
15.
Human bladder cancer cell lines, J82, Yen-87, Shen-87 and Zoa-88, and murine bladder cancer cell lines, MBT-2 and M1660, were used as target cells for dye-sensitized photoinactivation study in using methylene blue. Normal fibroblast cells, FB-1 and FB8490, were used as control group. The cytoplasmic activity of lactic dehydrogenase, soft agar clonogenic assay, and in vivo tumor growth, survival rate and tumor taking rate with or without photoinactivation were monitored and compared between different cell lines. Efficacy of photoinactivation was time-related and more than 90 per cent of cytotoxicity could be obtained within 60 minutes of illumination. The plateau of cytotoxicity curve could be achieved after staining for 30 minutes by methylene blue under the same illumination time. Normal fibroblasts had the same features with cancer cells. Photoinactivation of tumor cells showed significant inhibition of tumor growth and tumor taking rate in experimental animals. Survival rate was also significantly prolonged in the animals with tumor cells receiving photoinactivation. These results suggest that methylene blue-sensitized photoinactivation may be useful as an adjuvant photochemotherapy for superficial bladder cancer. 相似文献
16.
Five commercially available nitropolyclyclic aromatic hydrocarbons (nitro-PAH), namely, 4-nitrobiphenyl, 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene, and 2,7-dinitrofluorene, were exposed under restricted sunlight in the open air. The direct-acting mutagenicities of the samples after an exposure of 45 days were measured in order to compare them with those of the original samples in the Ames Salmonella typhimurium bioassay. It was found that the mutagenicities of some nitro-PAH do not change significantly while the mutagenicities of others increase or decrease after exposure. A preliminary study of nitro-PAH reaction products after exposure using GC, GC/MS, and FT-IR is also reported. 相似文献
17.
L Z Wu L H Zeng Q Y Ma Y J Xie Y Z Chen D Z Wu 《Japanese journal of ophthalmology》1988,32(2):236-245
The hereditary characteristics of enzyme deficiency and dermatoglyphics in congenital color blindness (CCB) were studied. We propose that there is a linkage between the two loci on the X-chromosome determining CCB and glucose-6-phosphate dehydrogenase (G6PD), based on our study of a high incidence of G6PD deficiency in 156 male cases with CCB. The CCB gene is closely linked with that of G6PD deficiency from our pedigree investigations. The rise in the frequency of eight or more whorls, the low value of atd angle and the presenting rate of real palmar patterns of the thenar, hypothenar and I, areas presented the hereditary traits of congenital color blindness. 相似文献
18.
Histamine (HA) concentrations and HA metabolizing enzyme activities were measured in macroscopically unchanged mammary glands and in tumor tissue of C3H mice carrying spontaneous mammary tumor as well as im mammary glands of control subjects matched for age.The great fall in HA level and the enzyme activities in tumor tissue was confirmed. In host mammary glands which showed no current evidence of neoplasm, consistently lower than normal HA concentrations and elevated transglutaminase (TG) activity were found, It is suggested, therefore, that HA level and TG activity may provide an early indication of the development of spontaneous mammary tumor. 相似文献
19.
Viral markers were studied in 79 cases of viral hepatitis with hepatic failure. The results were shown as follows: 8 cases were positive for anti-HAV IgM (10.12%); 76 cases positive for HBsAg or anti-HBc IgM (96.20%) and 41 cases positive for anti-HCV antibodies (51.89%). Among those with anti-HCV positive, 35 cases were co-infected with HBV, 5 cases with HAV and/or HCV, only one was infected with HCV alone 2 cases were HD-Ag positive (2.52%) and one not identified (1.27%). With the reference of clinical findings, patients co-infected with HBV/HCV or anti-HBc IgM positive were more critical and usually entail higher mortality. In cases with HCV co-infections, the positive HBV replication markers seems to be reduced. Hepatic failure without HBV replicative markers had a high rate of hepatic coma as well as poor outcome. 相似文献
20.
目的 :探讨外周血单个核细胞 (PBMC)内上游信号分子及核因子 κB(NF κB)在烧伤后炎症级联反应中的作用。 方法 :体外检测在烧伤血浆作用下的PBMC内游离Ca2 及NF κB活化的变化 ,观察钙通道阻断药对NF κB活化及IL 6、NO表达水平的调控作用。 结果 :不同时相点的烧伤血浆可使体外PBMC内Ca2 明显增加 ,培养的PBMC核内NF κB的积聚明显增加 ,培养上清中NO和IL 6高表达。应用尼莫通 (Nimodipine)和丹曲林 (Dantrium)对NF κB的活化有调节作用 ,对IL 6和NO亦有下调作用。 结论 :烧伤血浆可使PBMC内信号分子浓度明显增高 ,NF κB过度活化 ,并易位进入细胞核内 ,NF κB介导的促炎性细胞因子和NO过度表达。两种钙通道阻断药有调控细胞内信号转导的作用 ,对烧伤后全身炎症反应综合征 (SIRS)可能有防治作用 相似文献