全文获取类型
收费全文 | 32381篇 |
免费 | 2700篇 |
国内免费 | 1361篇 |
专业分类
耳鼻咽喉 | 393篇 |
儿科学 | 609篇 |
妇产科学 | 580篇 |
基础医学 | 3941篇 |
口腔科学 | 554篇 |
临床医学 | 3448篇 |
内科学 | 5473篇 |
皮肤病学 | 747篇 |
神经病学 | 2150篇 |
特种医学 | 1079篇 |
外国民族医学 | 13篇 |
外科学 | 4138篇 |
综合类 | 4058篇 |
现状与发展 | 4篇 |
一般理论 | 19篇 |
预防医学 | 1932篇 |
眼科学 | 1151篇 |
药学 | 2588篇 |
19篇 | |
中国医学 | 1086篇 |
肿瘤学 | 2460篇 |
出版年
2024年 | 61篇 |
2023年 | 434篇 |
2022年 | 935篇 |
2021年 | 1390篇 |
2020年 | 1029篇 |
2019年 | 970篇 |
2018年 | 1089篇 |
2017年 | 957篇 |
2016年 | 961篇 |
2015年 | 1257篇 |
2014年 | 1563篇 |
2013年 | 1500篇 |
2012年 | 2307篇 |
2011年 | 2347篇 |
2010年 | 1365篇 |
2009年 | 1140篇 |
2008年 | 1663篇 |
2007年 | 1695篇 |
2006年 | 1652篇 |
2005年 | 1659篇 |
2004年 | 1205篇 |
2003年 | 1033篇 |
2002年 | 922篇 |
2001年 | 784篇 |
2000年 | 800篇 |
1999年 | 776篇 |
1998年 | 459篇 |
1997年 | 379篇 |
1996年 | 298篇 |
1995年 | 302篇 |
1994年 | 244篇 |
1993年 | 183篇 |
1992年 | 308篇 |
1991年 | 299篇 |
1990年 | 282篇 |
1989年 | 265篇 |
1988年 | 231篇 |
1987年 | 211篇 |
1986年 | 203篇 |
1985年 | 157篇 |
1984年 | 107篇 |
1983年 | 75篇 |
1982年 | 56篇 |
1981年 | 56篇 |
1979年 | 76篇 |
1978年 | 52篇 |
1977年 | 53篇 |
1974年 | 65篇 |
1973年 | 60篇 |
1972年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
本文应用磁性磷酸酶-抗碱性磷酸酶桥联酶标技术(APAAP),对27例原发性肾小球疾病患者外周血T淋巴细胞亚群进行观察。结果表明:本组病例表现为CD细胞升高,CD细胞减少,和CD/CD比值增加。提示原发性肾小球疾病可导致细胞免疫功能改变,T淋巴细胞亚群的变化,是肾组织损害的一个间接证据,可作为临床诊断一个有价值的参考指标。 相似文献
22.
本文应用“冷沉淀”法制备纤维组织粘合剂。对纤维组织粘合剂中主要成份和含量进行了测定,并测定了主要理化性质,建立了动物实验模型,观察了实验兔对纤维粘合剂的反应。 相似文献
23.
Eight patients who developed severe ovarian hyperstimulation syndrome (OHSS) were identified among 1302 patients undergoing in-vitro fertilization (IVF) over a 1 year period (prevalence of 0.6%); 63% had ultrasonically diagnosed polycystic ovaries (PCO) and 75% were undergoing their first attempt at IVF. Pretreatment with a superactive luteinizing hormone-releasing hormone (LHRH) analogue significantly increased the prevalence of severe OHSS (1.1% versus 0.2%, P less than 0.05) compared with ovarian stimulation with clomiphene citrate and human menopausal gonadotrophin (HMG). The mean serum oestradiol concentration on the day of human chorionic gonadotrophin (HCG) administration was 8200 +/- 2300 pmol/l. A mean of 19.6 +/- 6.8 follicles had been aspirated and 13.1 +/- 7.7 oocytes recovered at transvaginal ultrasound-directed oocyte recovery. All patients had an embryo transfer and luteal support in the form of HCG. The clinical pregnancy rate was 88%, multiple pregnancy rate 71% and implantation rate 63.5 +/- 41.3%. In a group of seven patients who were hospitalized for moderate OHSS during the same period, peak oestradiol levels were significantly lower than in those with severe OHSS (P less than 0.05). Of the group with moderate OHSS, 57% had PCO, the clinical pregnancy rate was 100% and multiple pregnancy rate 43%. Patients with ultrasound-diagnosed PCO have an increased risk of developing OHSS and the dose of HMG administered to them should be minimized. In patients at risk of developing OHSS, progesterone instead of HCG should be used for luteal support. Transfer of a maximum of two embryos or freezing all embryos for transfer in a subsequent cycle may reduce the likelihood of multiple pregnancy. 相似文献
24.
Omeprazole May Kill Helicobacter pylori 总被引:2,自引:0,他引:2
K. L. Goh M.D. K. K. Tan M.D. P. E. Anderson M.D. 《The American journal of gastroenterology》1991,86(1):124-124
25.
26.
27.
A. TSATSOULIS E. WHITEHEAD J. ST. JOHN S. M. SHALET W. R. ROBERTSON 《Clinical endocrinology》1987,27(6):683-689
Eighteen men (mean age 27, range 18-30 years) treated for Hodgkin's disease with 6-8 courses of MVPP (Mustine, Vinblastine, Procarbazine and Prednisolone) have had Leydig cell function assessed by their steroidogenic responses to stimulation by a single bolus dose of HCG (1000 units intramuscularly). Normal age-matched men (n = 16) acted as controls. Baseline immunoreactive FSH was markedly raised in the patients (mean 18.1 +/- SD 6.9 vs 2.0 +/- 1.5 IU/l, P less than 0.0001) reflecting damage to the germinal epithelium. Immunoreactive LH was also greater in patients (10.3 +/- 3.9 IU/l) than in controls (3.9 +/- 1.9 IU/l, P less than 0.0001). There were no differences between the baseline testosterone, androstenedione, oestradiol, oestrone and sex hormone binding globulin (SHBG) concentrations. The testosterone/SHBG ratios were similar in the two groups and there was no correlation between baseline LH and testosterone concentrations or testosterone/SHBG ratios. Testosterone, androstenedione, oestradiol and oestrone secretion in response to HCG stimulation were similar at 24 h and 96 h in both groups. In order to explain the paradox of elevated immunoreactive LH in the face of normal testicular steroidogenesis in such patients, LH biological activity (B) as well as LH immunoreactivity (I) and FSH and testosterone were estimated in a second similar group of patients (n = 17, mean age 27, range 17-43 years) and in a further age-matched control group (n = 17). Bioactive and immunoreactive LH levels were significantly increased (P less than 0.005 and P less than 0.001, respectively) in the patient group.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
28.
Membrane flow within the myelin sheath in IDPN neuropathy 总被引:1,自引:0,他引:1
A. E. BLAUROCK M. B. GENTER ST CLAIR D. G. GRAHAM 《Neuropathology and applied neurobiology》1991,17(4):309-321
This report describes some aspects of beta,beta'-iminodipropionitrile (IDPN) neuropathy in rats as observed by ultrastructural methods and X-ray diffraction. Light microscopy shows gross swelling of the axons in proximal lumbar spinal roots 8 days after intraperitoneal injection of IDPN. Mean axon cross-sectional area and mean axon perimeter increased to 280% and 160% of their control values, respectively. At the same time, myelin membrane packing was not visibly disturbed. In addition, X-ray diffraction patterns, recorded under physiological conditions, demonstrate that the myelin lipid bilayer thickness and widths of the aqueous spaces between bilayers did not change. Related observations are made on posterior tibial nerve (PNS myelin) and ventral spinal cord (CNS myelin). The various observations together are interpreted in terms of a fluid myelin membrane. It is proposed that the myelin membrane flows during axon swelling even though normal membrane-membrane contacts are maintained within the sheath. Membrane flow and slippage between membranes are explained in terms of a molecular model of the myelin multilayer. 相似文献
29.
E C Tan 《The Journal of dermatologic surgery and oncology》1989,15(3):270-272
The punch technique of repairing pierced earlobe deformities is a practical and simplified alternative to the usual method of repair. The procedure can easily be performed in any dermatology office since the instruments required are very basic. The technique is presented in a series of illustrations, and the results are cosmetically acceptable. 相似文献
30.
Expression of antibody heavy- and light-chain genes by transfection permits the production of monoclonal antibodies with improved biological and antigen-binding properties. The immunoglobulin genes are placed in vectors containing a gene for encoding a protein that provides a biochemically selectable function in eukaryotic cells; these vectors are transfected into myeloma and hybridoma cells. Selection of drug-resistant cells permits the efficient isolation of the rare cells that express the transfected DNA. By placing heavy and light chains on plasmids with different selectable markers, one can deliver heavy- and light-chain genes simultaneously to the same cell. The transfected immunoglobulin genes are efficiently expressed and the proteins produced are a faithful mirror of the genes that were introduced. Using the standard techniques of genetic engineering and gene transfection, we can now produce antibodies of widely varying structures, including chimeric antibodies with segments derived from different species. These antibodies provide useful reagents to study structure-function relationships within the antibody molecule. Ultimately it will be possible to produce a new generation of antibody molecules with improved antigen-binding properties and effector functions. 相似文献