全文获取类型
收费全文 | 8045篇 |
免费 | 648篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 83篇 |
儿科学 | 315篇 |
妇产科学 | 108篇 |
基础医学 | 1022篇 |
口腔科学 | 101篇 |
临床医学 | 906篇 |
内科学 | 1428篇 |
皮肤病学 | 75篇 |
神经病学 | 682篇 |
特种医学 | 567篇 |
外科学 | 1083篇 |
综合类 | 200篇 |
现状与发展 | 1篇 |
一般理论 | 3篇 |
预防医学 | 819篇 |
眼科学 | 163篇 |
药学 | 665篇 |
中国医学 | 33篇 |
肿瘤学 | 452篇 |
出版年
2023年 | 37篇 |
2022年 | 45篇 |
2021年 | 108篇 |
2020年 | 71篇 |
2019年 | 102篇 |
2018年 | 126篇 |
2017年 | 110篇 |
2016年 | 96篇 |
2015年 | 129篇 |
2014年 | 191篇 |
2013年 | 253篇 |
2012年 | 384篇 |
2011年 | 394篇 |
2010年 | 282篇 |
2009年 | 253篇 |
2008年 | 390篇 |
2007年 | 414篇 |
2006年 | 353篇 |
2005年 | 334篇 |
2004年 | 335篇 |
2003年 | 306篇 |
2002年 | 303篇 |
2001年 | 265篇 |
2000年 | 238篇 |
1999年 | 212篇 |
1998年 | 140篇 |
1997年 | 133篇 |
1996年 | 124篇 |
1995年 | 129篇 |
1994年 | 98篇 |
1993年 | 103篇 |
1992年 | 181篇 |
1991年 | 161篇 |
1990年 | 140篇 |
1989年 | 141篇 |
1988年 | 147篇 |
1987年 | 138篇 |
1986年 | 115篇 |
1985年 | 142篇 |
1984年 | 109篇 |
1983年 | 98篇 |
1982年 | 64篇 |
1981年 | 69篇 |
1980年 | 65篇 |
1979年 | 75篇 |
1978年 | 57篇 |
1977年 | 55篇 |
1976年 | 36篇 |
1975年 | 40篇 |
1974年 | 46篇 |
排序方式: 共有8706条查询结果,搜索用时 0 毫秒
101.
102.
103.
Groopman JE; Hartzband PI; Shulman L; Salahuddin SZ; Sarngadharan MG; McLane MF; Essex M; Gallo R 《Blood》1985,66(3):742-744
The human T-lymphotropic virus type III (HTLV-III) is the primary cause of the acquired immunodeficiency syndrome (AIDS) and related disorders (ARC). Prior studies have reported that nearly all symptomatic patients with AIDS or ARC manifest antibody to HTLV-III. This observation has engendered efforts to screen for HTLV-III, especially prior to blood donation, with assays for antibody to HTLV-III. We report the first two cases, one with AIDS and one with ARC, that are HTLV-III virus positive but antibody negative. Accurate diagnosis of HTLV-III infection in some cases may require direct virus culture or tests for antigen. In addition, lack of HTLV-III antibody may indicate an atypical clinical course of AIDS. 相似文献
104.
Mapping of steroid 21-hydroxylase genes adjacent to complement component C4 genes in HLA, the major histocompatibility complex in man. 总被引:30,自引:12,他引:30 下载免费PDF全文
M C Carroll R D Campbell R R Porter 《Proceedings of the National Academy of Sciences of the United States of America》1985,82(2):521-525
The genes for four components (C) of complement in the human major histocompatibility complex (HLA) have been aligned previously in a series of overlapping cosmid cloned inserts. Those inserts, which contained the two C4 genes C4A and C4B, hybridized with human adrenal mRNA, indicating that they contain a gene expressed in the adrenal. The mRNA fraction of 2.4 kilobases (kb) hybridizes with genomic DNA of 4.5 kb, which is duplicated and lies about 1.5 kb 3' of both the C4A and the C4B complement genes. Sequencing of a 430-base section and comparison with the published cDNA sequence of bovine cytochrome P-450 21-hydroxylase, peptide sequences of porcine 21-hydroxylase, and a cDNA sequence of a rat liver cytochrome P-450 identified the gene as coding for human steroid 21-hydroxylase [steroid,hydrogen-donor:oxygen oxidoreductase (21-hydroxylating), EC 1.14.99.10]. Mapping of the gene was helped by use of a synthetic oligonucleotide based on the bovine cDNA sequence. 相似文献
105.
Although trace minerals are necessary constituents of enzymes, dietary requirements of these nutrients for the elderly are unknown. This study measured selenium balance in six dependent elderly men before and after five weeks daily administration of 200 micrograms organically-bound selenium; dietary selenium intake averaged 62.1 +/- 7 micrograms/day during both study periods. Selenium status was assessed not only chemically but also biologically as red cell and platelet glutathione peroxidase activities. Plasma selenium averaged 8.8 +/- 0.8 micrograms% (normal: 10 +/- 2 micrograms %) when intake derived from dietary sources alone and increased during medicinal supplementation to an average of 12.8 +/- 1.9 micrograms %. The rise in plasma selenium was not associated with an increase in red cell or platelet glutathione peroxidase activity. The effect of selenium supplementation on in vivo platelet aggregability was studied by measuring plasma levels of beta-thromboglobulin and platelet factor 4, two proteins secreted concomitant with aggregation. beta-thromboglobulin diminished 7.5 +/- 11.0 ng/ml and platelet factor 7.6 +/- 11.0 ng/ml during selenium supplementation despite no change in platelet glutathione peroxidase activity. These data support the concept that selenium nutritional status should be assessed not only by blood selenium content but also by selenium-dependent enzyme activity or selenium-dependent biologic effect. 相似文献
106.
Gastroduodenal mucus is present as a water insoluble gel adherent to the mucosal surface and as a viscous mobile solution in the lumen. The protective properties of the mucus against acid (with bicarbonate), pepsin (diffusion barrier) and mechanical damage depend on the quality (structure) and quantity (thickness) of the adherent mucus gel layer. Adherent mucus is a viscoelastic gel which is 95% (v/v) water. It is permeable to ions and smaller molecules (Mr c. 1000), but is impermeable to large proteins (Mr,c. 17,000) including pepsins. However, mucus is solubilized rapidly by pepsin, more slowly (>-1 h) by thiol agents, and is unchanged following exposure to bile, acid and ethanol (<40%). Glycoprotein macromolecules (Mr≥2×106) are the structural components of the mucus gel and have a polymeric, structure of glycoprotein subunits (Mrc. 5×105, for gastric mucus) joined by disulphide bridges between their protein cores. This glycoprotein polymerization, which is essential for gel formation and hence function, is the site of action of proteolytic enzymes and thiol agents. The glycoprotein polymeric structure is deficient in antral mucus from patients with peptic ulcer disease.In vivo, adherent mucus forms a thin but continuous cover of variable thickness (50–450 μm in man, about two-fold less in rat) over the gastroduodenal mucosa. Pepsin in gastric juice will rapidly dissolve this mucus cover and can be active up to luminal pH values of 5. Mucus erosion by pepsin or by abrasion must be balanced by its secretion. Prostaglandins and carbachol stimulate a rapid increase (within minutes) in mucus thickness of up to two-fold. Soluble luminal mucus can be increased by mucus secretagogues, mucosal damaging agents, or peptic degradation of adherent mucus. Increases in luminal mucus can occur independently of increased gel thickness. 相似文献
107.
Endovascular versus open approach to aortic aneurysm repair surgery: rates of postoperative delirium
Konrad Salata BHSc Rita Katznelson MD W. Scott Beattie MD PhD Jo Carroll RN Thomas F. Lindsay MD George Djaiani MD 《Journal canadien d'anesthésie》2012,59(6):556-561
Purpose
Our objective was to compare open and endovascular aortic aneurysm repair with respect to postoperative delirium.Methods
After Institutional Ethics Review Board approval, we conducted a retrospective review of all patients who underwent abdominal and thoraco-abdominal aortic aneurysm repair surgery at Toronto General Hospital during June 2006 to December 2007. Patients were classed into either the OPEN or the endovascular (EVAR) group based on the type of surgery and were assessed for the presence of delirium after surgery. The NEECHAM Confusion Scale and the validated chart review instrument were used for diagnosis of delirium. Patients with dementia and/or abnormal levels of consciousness preoperatively were excluded.Results
There were 256 patients included in the study, 149 (58%) in the OPEN group and 107 (42%) in the EVAR group. Patients in the EVAR group were considerably older, 74 (10) yr vs 68 (9) yr, and they had shorter duration of surgery, 150 [119, 180] min vs 200 [165, 260] min, respectively, P?<?0.0001. Postoperative delirium was present in 43 (29%) patients in the OPEN group and 14 (13%) patients in the EVAR group (95% confidence interval [CI], 22 to 36 vs 95% CI, 7 to 19, respectively; P?=?0.003). Hospital length of stay was 8.3 [6.6, 13.4] days in the OPEN group and 4.5 [3.1, 6.4] days in the EVAR group, P?<?0.0001.Conclusions
Perioperative management of patients undergoing endovascular aortic aneurysm repair was associated with lower rates of delirium after surgery than that of patients undergoing open aortic aneurysm repair. 相似文献108.
Ultrasound scanning of the pelvis with an empty bladder permits a true frontal view of the uterus to be easily obtained. This view is comparable to the en face view seen at hysterography performed with contrast material. Good definition both of the endometrium and the uterine wall makes this the optimal method for the evaluation of an intrauterine contraceptive device. 相似文献
109.
Downs TM Sadetsky N Pasta DJ Grossfeld GD Kane CJ Mehta SS Carroll PR Lubeck DP 《The Journal of urology》2003,170(5):1822-1827
PURPOSE: We measured the impact brachytherapy monotherapy (BMT) has on general and disease specific health related quality of life (HRQOL) compared to patients treated with radical prostatectomy (RP). MATERIALS AND METHODS: We studied 419 men with newly diagnosed prostate cancer who enrolled in CaPSURE (Cancer of the Prostate Strategic Urological Research Endeavor) data base whose primary treatment was brachytherapy monotherapy (92) or radical prostatectomy (327). The validated RAND 36-Item Health Survey and the UCLA Prostate Cancer Index were used to measure HRQOL before treatment and at 6-month intervals during the first 2 years after treatment. RESULTS: Patients treated with BMT or RP did not differ greatly in general HRQOL after treatment. Both treatment groups showed early functional impairment in most general domains with scores returning to or approaching baseline in most domains 18 to 24 months after treatment. Patients treated with BMT had significantly higher urinary function scores at 0 to 6 months after treatment (84.5, SD 18.7) than patients treated with RP (63.3, SD 26.6). Urinary bother scores at 0 to 6 months after treatment were not significantly different between patients treated with BMT (67.7, SD 31.2) and those treated with RP (67.4, SD 29.1). Both treatment groups had decreases in sexual function that did not return to pretreatment levels. CONCLUSIONS: Overall BMT and RP are well tolerated procedures that cause mild changes in general HRQOL. Disease specific HRQOL patterns are different in patients treated with BMT or RP. Baseline and serial HRQOL measurements after treatment can provide valuable information regarding expected quality of life outcome after treatment for localized prostate cancer. 相似文献
110.
Bello L Lucini V Giussani C Carrabba G Pluderi M Scaglione F Tomei G Villani R Black PM Bikfalvi A Carroll RS 《Neurosurgery》2003,52(1):177-85; discussion 185-6
OBJECTIVE: The biological features of malignant gliomas include high cell proliferation, extensive local infiltration of tumor cells into normal brain, and marked neovascularization. alphavbeta3 integrin is highly expressed in malignant gliomas and plays a role in glioma growth. This article investigates the in vitro and in vivo effects of a synthetic alphavbeta3 integrin inhibitor called IS20I on human malignant gliomas. METHODS: The in vitro effects of IS20I were studied by performing adhesion assays, competition studies, semi-in vivo angiogenic assays, and migration and proliferation assays. For the in vivo experiments, IS20I was administered systemically in nude mouse intracranial and subcutaneous malignant glioma models. RESULTS: IS20I reacted selectively to alphavbeta3 integrin in glioma cells and tissues. In vitro, IS20I strongly inhibited angiogenesis and simultaneously exhibited potent antimitotic and antimigratory effects on numerous tumor and endothelial cell lines. In addition, at high concentrations, IS20I induced endothelial and tumor cell apoptosis. In vivo, when IS20I was administered intraperitoneally in subcutaneous and intracranial nude mouse glioma models, it potently reduced malignant glioma growth. Inhibition levels of 76 and 82% were observed at concentrations of 1 and 5 mg/kg, respectively, in the U87 intracranial model. The suppression of tumor growth is associated with a decrease in tumor vascularity, an increase in apoptosis, and a decrease in tumor cell proliferation. CONCLUSION: This work expands the understanding of the effects of anti-alphavbeta3 integrin inhibitors on malignant gliomas. In addition to direct proapoptotic and antiangiogenic effects, IS20I inhibits tumor and endothelial cell proliferation and migration, resulting in a potent inhibition of glioma growth in vivo. 相似文献