全文获取类型
收费全文 | 6121篇 |
免费 | 669篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 90篇 |
儿科学 | 169篇 |
妇产科学 | 170篇 |
基础医学 | 829篇 |
口腔科学 | 216篇 |
临床医学 | 761篇 |
内科学 | 978篇 |
皮肤病学 | 140篇 |
神经病学 | 447篇 |
特种医学 | 253篇 |
外科学 | 833篇 |
综合类 | 236篇 |
一般理论 | 4篇 |
预防医学 | 622篇 |
眼科学 | 77篇 |
药学 | 573篇 |
中国医学 | 33篇 |
肿瘤学 | 415篇 |
出版年
2021年 | 94篇 |
2020年 | 52篇 |
2019年 | 110篇 |
2018年 | 125篇 |
2017年 | 83篇 |
2016年 | 110篇 |
2015年 | 111篇 |
2014年 | 144篇 |
2013年 | 225篇 |
2012年 | 252篇 |
2011年 | 328篇 |
2010年 | 192篇 |
2009年 | 153篇 |
2008年 | 247篇 |
2007年 | 288篇 |
2006年 | 241篇 |
2005年 | 229篇 |
2004年 | 231篇 |
2003年 | 215篇 |
2002年 | 196篇 |
2001年 | 194篇 |
2000年 | 185篇 |
1999年 | 157篇 |
1998年 | 78篇 |
1997年 | 58篇 |
1996年 | 72篇 |
1995年 | 61篇 |
1994年 | 55篇 |
1993年 | 61篇 |
1992年 | 120篇 |
1991年 | 133篇 |
1990年 | 136篇 |
1989年 | 133篇 |
1988年 | 133篇 |
1987年 | 136篇 |
1986年 | 123篇 |
1985年 | 116篇 |
1984年 | 95篇 |
1983年 | 86篇 |
1982年 | 68篇 |
1979年 | 75篇 |
1978年 | 57篇 |
1976年 | 39篇 |
1975年 | 46篇 |
1974年 | 66篇 |
1973年 | 70篇 |
1972年 | 52篇 |
1971年 | 52篇 |
1970年 | 43篇 |
1969年 | 50篇 |
排序方式: 共有6846条查询结果,搜索用时 93 毫秒
31.
M R Duncan T J Wilson J Van De Water B Berman R Boyd G Wick M E Gershwin 《Journal of autoimmunity》1992,5(5):603-615
University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma. 相似文献
32.
Epidemiologic evidence for early onset of mental disorders and higher risk of drug abuse in young adults 总被引:8,自引:0,他引:8
K A Christie J D Burke D A Regier D S Rae J H Boyd B Z Locke 《The American journal of psychiatry》1988,145(8):971-975
Data from the National Institute of Mental Health (NIMH) Epidemiologic Catchment Area Program, an epidemiologic survey of five communities, showed that four major disorders commonly begin in late adolescence or young adulthood. The median age at onset for anxiety disorders is 15 years; for major depressive episode, 24 years; for drug abuse or dependence, 19 years; and for alcohol abuse or dependence, 21 years. Findings also suggest that for respondents 18-30 years old, having a major depressive episode or anxiety disorder doubles the risk for later drug abuse or dependence. 相似文献
33.
Emergency room resuscitative thoracotomy: when is it indicated? 总被引:3,自引:0,他引:3
This study was designed to examine the results of emergency room resuscitative thoracotomy (ERRT) and to formulate cost-effective indications for this procedure. A retrospective study was performed of 28 patients who had ERRT at St. Elizabeth Hospital Medical Center, Youngstown, Ohio, during the 4 years from July 1985 through June 1989. The prognostic factors analyzed included mechanism and site of injury, signs of life (SOL), vital signs (VS), age, gender, and prehospital care. The overall survival rate of ERRT was 7% (2 of 28 patients). The survival rate was 18% (2 of 11 patients) with penetrating trauma, and 0% (none of 17 patients) with blunt trauma. The best survival rate was 66% in the subgroup of patients with penetrating trauma and SOL present at the scene and in the emergency room (ER), (two of three patients). Our observations were combined with those of 23 studies from the literature involving 2294 trauma patients who had ERRT. Using meta-analysis, the survival rate was 11% overall. Improved survival was noted for patients with penetrating trauma compared with patients with blunt trauma (14% vs. 2%, p < 0.01). There were no survivors in the group of patients with no SOL at the scene, and there were no neurologically intact survivors among blunt trauma patients with no SOL upon arrival at the ER. An algorithm based on mechanism of injury and presence or absence of SOL at the scene and in the ER is proposed. This algorithm would decrease the number of ERRTs performed by 41% without decreasing the number of neurologically intact survivors.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
34.
Shoulder dysfunction is unusual in osteoarthritis and usually responds to conservative treatment. The primary indication for surgery is pain unresponsive to medical management. The procedure of choice for degenerative changes in the glenohumeral joint is hemiarthroplasty or total shoulder replacement depending on the condition of the glenoid. Shoulder fusion is rarely necessary for osteoarthritis and is recommended for chronic infection, flail shoulder, and failed total shoulder replacement not amenable to revision. Joint resection is reserved for infected joints with massive bone loss. The results of shoulder arthroplasty are good to excellent in 86 to 94 per cent of all patients. The results of shoulder arthrodesis are less predictable, but are usually satisfactory in approximately 75 per cent of patients with 10-year follow-up. The treatment of AC and SC joint arthritis is conservative with rest, local heat, and medication. Pain unresponsive to this regimen is an indication for resection of the joint. Good results with this procedure directly correlate with pain relief on injection of the joint with local anesthetic. 相似文献
35.
S A Boyd A K Fung W R Baker R A Mantei Y L Armiger H H Stein J Cohen D A Egan J L Barlow V Klinghofer 《Journal of medicinal chemistry》1992,35(10):1735-1746
We describe the development of a series of soluble, potent, and bioavailable nonpeptide renin inhibitors. These inhibitors derived from a series of novel nonpeptide renin inhibitors which were recently identified in our laboratories, by alteration of the nature of the C-terminus (P2') of the molecules. Introduction of basic substituents into modified hydroxyethylene dipeptide isosteres gave inhibitors with improved solubility as well as improved potency against human plasma renin. In addition, these modifications produced inhibitors which displayed markedly improved intraduodenal bioavailability in both the ferret and cynomolgus monkey. We also present data which demonstrate excellent efficacy in the monkey for A-74273 (65), with an intraduodenal bioavailability of 16 +/- 4% in the monkey, compared to 1.7 +/- 0.5% for the dipeptide renin inhibitor enalkiren (A-64662, 75). A-74273 is an example of a nonpeptide inhibitor which possesses a good balance of the desirable properties of potency, solubility, and lipophilicity and which is well absorbed into the intestine. 相似文献
36.
37.
Patients undergoing radical prostatectomy following failed definitive radiation therapy for adenocarcinoma of the prostate run a substantial risk of refractory bladder neck contractures and urinary incontinence developing. A combined reconstructive technique utilizing a urethral pull-through procedure and implantation of an artificial urinary sphincter to treat these complications is described. When a patient can truly be cured by radical prostatectomy, this relatively straightforward reconstruction can salvage what otherwise would be considered a surgical failure. 相似文献
38.
39.
Kristin K Zorn Tomas Bonome Lisa Gangi Gadisetti V R Chandramouli Christopher S Awtrey Ginger J Gardner J Carl Barrett Jeff Boyd Michael J Birrer 《Clinical cancer research》2005,11(18):6422-6430
PURPOSE: The presence of similar histologic subtypes of epithelial ovarian and endometrial cancers has long been noted, although the relevance of this finding to pathogenesis and clinical management is unclear. Despite similar clinical characteristics, histologic subtypes of cancers of the ovary and endometrium are treated according to organ of origin. This study compares the gene expression profiles of analogous histologic subtypes of cancers of the ovary and endometrium using the same genomic platform to determine the similarities and differences between these tumors. EXPERIMENTAL DESIGN: Gene expression profiles of 75 cancers (endometrioid, serous, and clear cell) of the ovary and endometrium, five renal clear cell cancers, and seven normal epithelial brushings were determined using a 11,000-element cDNA array. All images were analyzed using BRB ArrayTools. Validation was done using real-time PCR on select genes and immunohistochemical staining. RESULTS: Comparison across endometrial and ovarian cancers and serous and endometrioid tumors showed expression patterns reflecting their organ of origin. Clear cell tumors, however, showed remarkably similar expression patterns regardless of their origin, even when compared with renal clear cell samples. A set of 43 genes was common to comparisons of each of the three histologic subtypes of ovarian cancer with normal ovarian surface epithelium. CONCLUSIONS: The comparison of the gene expression profiles of endometrioid and serous subtypes of ovarian and endometrial cancer are largely unique to the combination of a particular subtype in a specific organ. In contrast, clear cell cancers show a remarkable similarity in gene expression profiles across organs (including kidney) and could not be statistically distinguished. 相似文献
40.
Jennifer C. Chen Katrina L. Schmid Brian Brown Marion H. Edwards Bibianna SY Yu John KF Lew 《Clinical & experimental optometry》2003,86(5):323-330
Purpose: Caucasian children with myopia have elevated response accommodative vergence to accommodation (AC/A) ratios. The purpose of this study was twofold: to determine if response AC/A ratios vary with refractive error and with myopic progression rate in Hong Kong Chinese children, and to determine the effect of beta‐adrenergic antagonism with topical timolol application on AC/A ratios. Methods: Thirty children aged eight to 12 years participated in the study. All refractive errors were corrected with spectacle lenses. Accommodative responses were measured using a Shin‐Nippon autorefractor and concurrent changes in vergence were assessed using a vertical prism and a Howell‐Dwyer card at three metres and 0.33 metre. Accommodative demand was altered using plus or minus two dioptre lenses and lens‐ and distance‐induced response AC/A ratios were calculated. Measurements were repeated 30 minutes after the instillation of topical timolol maleate (0.5 per cent). Results: AC/A ratios appeared higher in progressing myopic children but the difference was not statistically significant. Timolol application reduced accommodative convergence (AC) in the stable myopes (reduction = ‐3 ± 1.14A) but not in the emmetropes (0.69 ± 0.9P) or progressing myopes (0.16 ± 0.43A) and this difference between refractive groups was statistically s ignificant (F2,27= 3.766; P= 0.036). However, timolol did not produce a significant change in the accommodative response to positive or negative lenses or response AC/A ratios. Conclusions: We did not find that AC/A ratios in myopic Chinese children were elevated and therefore, it is unlikely that elevated AC/A ratios are responsible for the high levels of myopia that occur in Hong Kong. The finding that timolol reduced AC in the stable myopes suggests that the autonomic control of accommodative convergence in these children may be different from that in emmetropic children and those with progressing myopia. 相似文献