全文获取类型
收费全文 | 23641篇 |
免费 | 2108篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 226篇 |
儿科学 | 619篇 |
妇产科学 | 583篇 |
基础医学 | 2783篇 |
口腔科学 | 404篇 |
临床医学 | 2373篇 |
内科学 | 4867篇 |
皮肤病学 | 394篇 |
神经病学 | 2195篇 |
特种医学 | 799篇 |
外国民族医学 | 3篇 |
外科学 | 3633篇 |
综合类 | 512篇 |
一般理论 | 43篇 |
预防医学 | 2605篇 |
眼科学 | 313篇 |
药学 | 1596篇 |
中国医学 | 30篇 |
肿瘤学 | 1796篇 |
出版年
2022年 | 149篇 |
2021年 | 362篇 |
2020年 | 212篇 |
2019年 | 408篇 |
2018年 | 514篇 |
2017年 | 352篇 |
2016年 | 320篇 |
2015年 | 420篇 |
2014年 | 586篇 |
2013年 | 861篇 |
2012年 | 1191篇 |
2011年 | 1241篇 |
2010年 | 753篇 |
2009年 | 681篇 |
2008年 | 1143篇 |
2007年 | 1237篇 |
2006年 | 1230篇 |
2005年 | 1198篇 |
2004年 | 1086篇 |
2003年 | 1023篇 |
2002年 | 933篇 |
2001年 | 615篇 |
2000年 | 653篇 |
1999年 | 588篇 |
1998年 | 297篇 |
1997年 | 224篇 |
1996年 | 232篇 |
1995年 | 243篇 |
1994年 | 182篇 |
1993年 | 175篇 |
1992年 | 433篇 |
1991年 | 418篇 |
1990年 | 371篇 |
1989年 | 379篇 |
1988年 | 345篇 |
1987年 | 327篇 |
1986年 | 298篇 |
1985年 | 321篇 |
1984年 | 266篇 |
1983年 | 227篇 |
1982年 | 176篇 |
1981年 | 158篇 |
1979年 | 250篇 |
1978年 | 178篇 |
1977年 | 152篇 |
1974年 | 164篇 |
1973年 | 194篇 |
1972年 | 190篇 |
1971年 | 161篇 |
1969年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
A comparative analysis of radiological and surgical placement of central venous catheters 总被引:3,自引:1,他引:2
Kieran D. McBride Ross Fisher Neil Warnock David A. Winfield Malcolm W. Reed Peter A. Gaines 《Cardiovascular and interventional radiology》1997,20(1):17-22
Purpose To compare the differences in practice and outcome of all radiologically and surgically placed central venous catheters retrospectively
over a 2-year period simultaneously, at a single institution.
Methods A total of 253 Hickman catheters were inserted in 209 patients; 120 were placed radiologically in 102 patients and 133 were
placed surgically in 107 patients. The indication was chemotherapy in 76% of radiological and in 47% of surgical cases; the
remainder were for total parenteral nutrition and venous access.
Results There were 6 (4.5%) primary surgical failures and a further 17 (13%) surgical cases requiring multiple placement attempts.
Pneumothorax occurred once (0.8%) surgically and four times (3.3%) radiologically. There were no radiological primary misplacements
but there were five (3.7%) surgical ones. Catheter or central vein thrombosis occurred in four (3.3%) radiological and five
(3.7%) surgical cases. The rate of infection per 1000 catheter-days was 1.9 in radiologically placed catheters and 4.0 in
surgically placed ones (p<0.001). Average catheter life-span was similar for the two placement methods (100±23 days).
Conclusion Radiological placement is consistently more reliable than surgical placement. There are fewer placement complications and
fewer catheter infections overall. 相似文献
62.
63.
64.
Laura K Brennan Elizabeth A Baker Debra Haire-Joshu Ross C Brownson 《Health education & behavior》2003,30(6):740-755
Although the relationship of psychosocial factors to physical activity has been explored, there is increased interest in how perceptions of the community environment influence behavior. However, few methodological studies have incorporated perceptions of the social and community environment (protective social factors) or addressed key measurement issues. Computer-assisted telephone interviews were administered to a national sample of 1,818 U.S. adults. Unadjusted and multivariate-adjusted odds ratios were calculated to compare active and inactive participants by Protective Social Factors (PSF) scores and selected sociodemographics. Confirmatory factor analysis and reliability analysis suggested strong PSF scale psychometric properties (alpha = .92). After adjustment for potential confounders, a 10-point rise in the PSF score resulted in a 12% increased likelihood of meeting Centers for Disease Control and Prevention/American College of Sports Medicine recommendations. Additional analyses indicated that greater perceived PSFs were associated with meeting these recommendations among Whites but not among African Americans. 相似文献
65.
The authors compared 57 patients with multiple personality disorder (MPD) who had been hypnotized both before and after diagnosis to 38 patients who had not been hypnotized during assessment or treatment. The two groups did not differ on the diagnostic criteria for MPD or in number of personalities. Hypnosis therefore does not have a gross distorting effect on the features of the disorder. Hypnosis may, however, affect the recall of sexual and physical abuse and the manifestation of certain types of alter personality. These include child personalities, personalities of different age, sex, or race, and protectors. The authors hypothesize that the hypnotized group may require hypnosis for access of more traumatic memories held by child personalities. 相似文献
66.
67.
Zvi Bar-Shavit Ronald L. Horst Jean C. Chappel F. Patrick Ross Richard W. Gray Steven L. Teitelbaum M.D. 《Calcified tissue international》1986,39(5):328-333
Summary 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is a potent inducer of monocytic differentiation of the human promyelocytic leukemia cell line, HL-60. We have noted that
25-hydroxyvitamin D3 (25(OH)D3) in high doses is also capable of promoting monocytic differentiation of this cell line. To test the possibility that the
latter activity is due to conversion of 25OHD3 to 1,25(OH)2D3 by HL-60, we exposed HL-60 cells to 25OHD3 and analyzed the products by HPLC and radioreceptor assay. When chromatographed in the traditional solvent system (isopropanol-hexane),
a new peak appears which migrates with authentic 1,25(OH)2D3. However, in a solvent system containing dichloromethane, 90% of the peak migrates with another metabolite, 19-Nor-10-Keto-25OHD3 (19-Nor-25OHD3). Production of this metabolite is enhanced by living cells and is synthesized by both virgin HL-60 and those which have
undergone differentiation. We next determined if authentic 19-Nor-25OHD3 also promotes differentiation of this cell. As assessed by appearance of the monocyte-specific surface antigen (63D3) and
macrophage-specific esterase activity, we find that this metabolite does, in fact, induce monocytic differentiation of HL-60
with a potency of approximately 1/200 that of 1,25(OH)2D3 and similar to that of 25OHD3. In agreement with the effect upon cell maturation, 19-Nor-25OHD3 displaces3H-1,25(OH)2D3 from its HL-60 receptor with an efficiency comparable to 25OHD3. Hence, HL-60 cells convert 25OHD3 to 19-Nor-25OHD3, and 19-Nor-25OHD3 induces monocytic differentiation of HL-60 with comparable efficiency to its precursor, 25OHD3. 相似文献
68.
R T Ross 《The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques》1991,18(3):312-320
The clinical functions of the posterior columns of the spinal cord and the signs of disease of these structures have been debated for years. Todd in 1847 and Schiff in 1858 knew the functions of the posterior columns and 10 years later Brown-Séquard knew as well. Reynolds, Romberg, and Duchenne, each described a posterior column syndrome based on a disease in which the primary lesion was not in the posterior columns. In the last 150 years almost every white matter structure of the cord has been credited with serving the sensations that we now know are a function of the posterior columns. Vibration, joint position and movement as well as discriminatory touch each seem to be served by separate fibres of the posterior columns and medial lemniscus. There is evidence of this in cat and man. These sensations may be lost individually, totally, or in certain stereotyped combinations. Vibration or joint sense is commonly lost alone. When a discriminatory touch sensation is lost with one other sense, it is almost inevitably joint position sense. Absent discriminatory touch and vibration sense with normal joint position sense appears to be unknown. This functional separation continues into the thalamus. At the highest level there is no evidence that vibration sense has any conscious somatosensory cortical affiliation, while joint position and discriminatory touch senses definitely do. 相似文献
69.
70.