全文获取类型
收费全文 | 24664篇 |
免费 | 2543篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 225篇 |
儿科学 | 696篇 |
妇产科学 | 614篇 |
基础医学 | 3402篇 |
口腔科学 | 611篇 |
临床医学 | 2913篇 |
内科学 | 5098篇 |
皮肤病学 | 357篇 |
神经病学 | 2381篇 |
特种医学 | 771篇 |
外科学 | 3226篇 |
综合类 | 593篇 |
一般理论 | 15篇 |
预防医学 | 2551篇 |
眼科学 | 455篇 |
药学 | 2117篇 |
1篇 | |
中国医学 | 29篇 |
肿瘤学 | 1175篇 |
出版年
2021年 | 360篇 |
2020年 | 202篇 |
2019年 | 352篇 |
2018年 | 407篇 |
2017年 | 328篇 |
2016年 | 313篇 |
2015年 | 370篇 |
2014年 | 518篇 |
2013年 | 769篇 |
2012年 | 1120篇 |
2011年 | 1159篇 |
2010年 | 666篇 |
2009年 | 555篇 |
2008年 | 1001篇 |
2007年 | 1169篇 |
2006年 | 1093篇 |
2005年 | 1127篇 |
2004年 | 1004篇 |
2003年 | 1067篇 |
2002年 | 957篇 |
2001年 | 692篇 |
2000年 | 699篇 |
1999年 | 599篇 |
1998年 | 281篇 |
1997年 | 227篇 |
1996年 | 210篇 |
1995年 | 257篇 |
1994年 | 226篇 |
1992年 | 524篇 |
1991年 | 483篇 |
1990年 | 470篇 |
1989年 | 463篇 |
1988年 | 418篇 |
1987年 | 426篇 |
1986年 | 375篇 |
1985年 | 450篇 |
1984年 | 381篇 |
1983年 | 299篇 |
1982年 | 285篇 |
1981年 | 234篇 |
1980年 | 242篇 |
1979年 | 350篇 |
1978年 | 295篇 |
1977年 | 210篇 |
1976年 | 243篇 |
1975年 | 215篇 |
1974年 | 277篇 |
1973年 | 286篇 |
1972年 | 236篇 |
1971年 | 216篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
121.
P Froom J Benbassat M Gross J Ribak B S Lewis 《Aviation, space, and environmental medicine》1988,59(3):278-281
The epidemiology of sudden death, the etiology of inflight sudden incapacitation, and the influence of pilot age and experience on air accident rates are reviewed in order to determine the aeromedical emphasis needed to minimize accidents. Sudden deaths in men over age 35 are nearly all due to coronary artery disease, whereas in those under 35 years they are mostly due to hypertrophic cardiomyopathy. The incidence of fatal accidents from human error is, however, far greater than that from physical illness. Since inexperienced pilots have a 2-3 times increased incidence of mishaps due to pilot error, the estimated risk of disease related in-flight sudden incapacitation should be balanced by consideration of pilot experience. Therefore, it may be preferable to grant waivers to experienced pilots with an increased incidence of disease-related inflight sudden incapacitation than to replace them with novices. We conclude that overly strict medical criteria may paradoxically increase accident rates. 相似文献
122.
123.
124.
Bruce E. Lewis Colin Sumida Ming H. Hwang Henry S. Loeb 《Catheterization and cardiovascular interventions》1992,26(4):295-299
Four selected cases of emergent IABP insertion in PV patients are presented. After angiographic documentation of critical iliac stenosis, conservative peripheral angioplasty was performed prior to IABP insertion. No patient experienced a peripheral ischemic event associated with IABP use. © 1992 Wiley-Liss, Inc. 相似文献
125.
126.
In the absence of clinically positive regional nodes, any value of prophylactic dissection in malignant melanomas depends on accurate preoperative determination of the pathway of lymphatic drainage. We report on the use of noninvasive radionuclide lymphoscintigraphy in the determination of regional patterns of lymph node drainage in patients with melanomas. Ten patients were studied; treatment was altered by test results in 2. Eleven node groups were excised in 7 patients. There have been no metastatic melanomas found in any nodal basins not detected by lymphoscintigraphy 23 to 42 months after operation. 相似文献
127.
Uttam C. Garg Lakshmi Devi Herman Turndorf Lewis R. Goldfrank Mylarrao Bansinath 《Brain research》1992,592(1-2):208-212
In the brain, nitric oxide (NO) has been identified as a messenger molecule and a mediator of excitatory amino acid-induced neurotoxicity. In this study, the effects of NO on serum-induced mitogenesis and cell proliferation of the cerebellar glial cells were assessed. NO-generating agent, S-nitroso-N-acetylpenicillamine (SNAP) increased intracellular cyclic guanosine monophosphate (cGMP) levels. Furthermore, 2 chemically dissimilar NO-generating agents, SNAP and sodium nitroprusside (SNP) inhibited serum-induced thymidine incorporation and cell proliferation. The antimitogenic effect of NO was mimicked by 8-bromo-cGMP and blocked by hemoglobin, a known inhibitor of NO. The effect of NO was not cytotoxic, since the cells were not stained with Trypan blue and did not show increased release of lactate dehydrogenase in the culture supernatants. However, NO-treated cells showed decreased conversion of tetrazolium to blue formazan suggesting that NO inhibited mitochondrial activity in the glial cells. These results demonstrate that NO inhibits serum-induced mitogenesis and cell proliferation of cultured rat cerebellar glial cells. 相似文献
128.
J Campbell N Wathen M Lewis H Fingerova T Chard 《British journal of obstetrics and gynaecology》1992,99(12):974-976
OBJECTIVE: The aim was to measure erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid from 7-12 weeks' gestation. SUBJECTS: Twenty healthy women with ultrasonographically normal first trimester pregnancies prior to surgical termination. METHODS: Paired samples of amniotic fluid and extraembryonic coelomic fluid were collected by transvaginal ultrasound guided needling. Erythropoietin was measured in both pregnancy fluids using a radioimmunoassay. RESULTS: There was a highly significant difference between erythropoietin levels in extraembryonic coelomic fluid (median level 15.45 mU/ml; range 6.8-32.1 mU/ml) and those in amniotic fluid (median 5.0 mU/ml; range < 5.0-5.8 mU/ml) (P < 0.0001; Mann-Whitney U-test). The levels of erythropoietin in maternal serum (median 15.4 mU/ml; range 5.6-29.4 mU/ml) were similar to those in the extra-embryonic coelom (P = 0.81; Mann-Whitney U-test). No relation was demonstrated between erythropoietin levels in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSION: High levels of erythropoietin in coelomic fluid suggests that the hormone is involved in the process of human extraembryonic erythropoiesis. The exact regulatory role remains unknown. 相似文献
129.
Non-obstructive colonic dilatation was diagnosed in six of 13,641 patients admitted to a Level I trauma centre over a 70-month period (incidence, less than 0.05 per cent). Four were older than 60 years, and five required long-term support on a ventilator. Successful treatment depends on expeditious decompression of the dilated colon. Fibreoptic colonoscopy is the recommended method. 相似文献
130.
R.P. Butt J.P. Huggins D. Greiling B. Hopkins S. Gaboardi D. Winslow M. Ronald S. Lewis S. Ward E. Levett J. Owen F. Burslem M. Collis S. Bailey P.V. Fish G. Whitlock S. Billotte K. James A. Mcelroy J. Blagg 《International journal of experimental pathology》2004,85(1):A20-A21
Introduction Fibrosis is a component of many tissue pathologies leading to loss of normal tissue function, primarily due to excessive collagen deposition. Collagen is deposited following cleavage of the C- and N- terminal peptides from the pro-collagen molecule. The cleavage of the globular C-peptide by PCP reduces solubility of the fibrillar collagen molecule, resulting in deposition of insoluble collagen. Increased insoluble collagen deposition is a feature of all organ fibroses, with inhibition of this process, a key potential anti-fibrotic mechanism. The aim of this work was to discover potent and selective PCP inhibitors as experimental, topically applied, anti-fibrotic drugs for clinical evaluation.
Materials and methods PCP was cloned from human osteosarcoma cells and enzymatic activity demonstrated using a PCP-specific peptide cleavage assay. Activities were confirmed by measuring cleavage of [3 H]C-peptide from type-I pro-collagen. A cell-based fibroplasias model was employed to demonstrate compound efficacy using collagen deposition, liberated C-peptide and histological endpoints. The activities of PCP inhibitors in fibroblast and epithelial in vitro cell proliferation and migration assays, and selectivity vs. a panel of MMPs were also determined.
Discussion In summary, we have identified and characterized potent and selective inhibitors of PCP for progression to clinical studies for investigation as a treatment paradigm for fibrotic disease.
Materials and methods PCP was cloned from human osteosarcoma cells and enzymatic activity demonstrated using a PCP-specific peptide cleavage assay. Activities were confirmed by measuring cleavage of [
Discussion In summary, we have identified and characterized potent and selective inhibitors of PCP for progression to clinical studies for investigation as a treatment paradigm for fibrotic disease.
Results 相似文献