全文获取类型
收费全文 | 104564篇 |
免费 | 12304篇 |
国内免费 | 4861篇 |
专业分类
耳鼻咽喉 | 1206篇 |
儿科学 | 2258篇 |
妇产科学 | 1249篇 |
基础医学 | 7587篇 |
口腔科学 | 2442篇 |
临床医学 | 13731篇 |
内科学 | 12235篇 |
皮肤病学 | 1397篇 |
神经病学 | 3473篇 |
特种医学 | 4279篇 |
外科学 | 10165篇 |
综合类 | 22054篇 |
现状与发展 | 13篇 |
一般理论 | 21篇 |
预防医学 | 13672篇 |
眼科学 | 1410篇 |
药学 | 10382篇 |
119篇 | |
中国医学 | 8528篇 |
肿瘤学 | 5508篇 |
出版年
2024年 | 493篇 |
2023年 | 1475篇 |
2022年 | 2868篇 |
2021年 | 3798篇 |
2020年 | 3382篇 |
2019年 | 1952篇 |
2018年 | 2477篇 |
2017年 | 2975篇 |
2016年 | 2491篇 |
2015年 | 4055篇 |
2014年 | 5113篇 |
2013年 | 6680篇 |
2012年 | 8364篇 |
2011年 | 8722篇 |
2010年 | 7743篇 |
2009年 | 7033篇 |
2008年 | 7091篇 |
2007年 | 6865篇 |
2006年 | 6139篇 |
2005年 | 4972篇 |
2004年 | 3618篇 |
2003年 | 3069篇 |
2002年 | 2528篇 |
2001年 | 2431篇 |
2000年 | 1816篇 |
1999年 | 1201篇 |
1998年 | 625篇 |
1997年 | 642篇 |
1996年 | 624篇 |
1995年 | 522篇 |
1994年 | 446篇 |
1993年 | 397篇 |
1992年 | 625篇 |
1991年 | 575篇 |
1990年 | 537篇 |
1989年 | 529篇 |
1988年 | 501篇 |
1987年 | 476篇 |
1986年 | 476篇 |
1985年 | 469篇 |
1984年 | 360篇 |
1983年 | 333篇 |
1982年 | 246篇 |
1981年 | 255篇 |
1979年 | 291篇 |
1978年 | 242篇 |
1977年 | 229篇 |
1974年 | 208篇 |
1973年 | 224篇 |
1972年 | 194篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Jonas T. Johnson MD Editor John K. Niparko MD Editor-in-Chief Paul A. Levine MD Editor David W. Kennedy MD Editor Pete Weber MD Editor-in-Chief Randal S. Weber MD Editor Michael S. Benninger MD Past Editor in Chief Richard M. Rosenfeld MD MPH Editor in Chief Robert J. Ruben MD Editor in Chief Richard J.H. Smith MD Editor in Chief Robert Thayer Sataloff MD DMA Editor in Chief Neil Weir MA FRCS Editor Emeritus 《Otolaryngology--head and neck surgery》2006,135(6):829-830
92.
Sylvie Naar-King Kathryn Wright Jeffrey T Parsons Maureen Frey Thomas Templin Phebe Lam Debra Murphy 《AIDS education and prevention》2006,18(1):1-11
This study piloted a brief individual motivational intervention targeting multiple health risk behaviors in HIV-positive youth aged 16-25. Interviews about sexual behavior and substance use and viral load testing were obtained from 51 HIV-positive youth at baseline and post intervention. Youth were randomized to receive a four-session motivational enhancement intervention (N = 25) or to a wait-list control (N = 26). Of the eligible youth approached, 88% agreed to participate, and 80% percent of participants completed at least three of four sessions. The treatment group showed significantly greater reductions in unprotected sex acts and in viral load compared with controls. Although change scores for substance use were not significantly different between the two groups, paired t tests demonstrated that reductions in alcohol use and marijuana use were significant for the treatment group at the trend level. There were no significant differences in substance use from baseline to posttest for the control group. Findings demonstrate the potential of a brief motivational enhancement intervention to improve health risk behaviors in HIV-positive youth. Larger randomized clinical trials are warranted. Resources required for retention should not be underestimated. 相似文献
93.
94.
95.
Kiyoshi Hashizume Kazuo Ichikawa Satoru Suzuki Teiji Takeda Keishi Yamauchi Mutsuhiro Kobayashi Xiao-Yun MA 《Journal of bone and mineral metabolism》1992,10(2):39-49
Calorie restriction is important in managing patients with maturity onset diabetes mellitus (NIDDM). The effect of such restriction
on calcium metabolism is not known. The objective of this study was to determine whether patients on calorie restricted diets
would show any modification of parathyroid hormone (PTH) and calcitonin (CTN).
The serum levels of PTH and CTN were measured by radioimmunoassays in 269 patients with NIDDM. The patients were divided into
two groups depending on the intake of calorie, and PTH and CTN were monitored for 2 years. Plasma levels of vitamin D were
measured by competitive protein binding assays before and after each program.
The level of PTH (520.8±266.0 pg/ml) (mean±S.D.) was significantly (P<0.01) higher in 109 diabetic patients whose calorie intake was restricted for 2 years (diet (D) group) as compared with that
(256.6±103.8 pg/ml) of 160 diabetic patients whose calorie intake was not restricted (non-diet (ND) group). The daily oral
calcium intake of the two groups did not differ significantly. We found no significant difference in the serum PTH level in
the ND groupVS. normal control subjects (248.8±98.4, N=78). The serum calcium concentration and the amount of calcium excreted in urine
were slightly but significantly (P<0.01) lower in the D than in the ND group. The rate of tubular reabsorption of phosphate (% TRP) was significantly lower
in the D group than that in the ND group (P<0.01). The serum CTN level was significantly (P<0.01) lower in the D group (33.9±11.3 pg/ml) than in the ND group (64.9±21.2 pg/ml) 2 years after each treatment. The plasma
1,25-(OH)2-vitamin D level was significantly (P<0.01) lower in the D group (22.2±6.6 pg/ml) than in the ND group (50.6±4.2 pg/ml). When
the restriction of calorie intake in the D group was canceled, their PTH levels decreased, which was accompanied by increase
in the 1,25-(OH)2-vitamin D levels, whereas their CTN levels were unchanged.
These observations suggested that a restricted calorie intake is a risk factor for secondary hyperparathyroidism as well as
for a low serum level of CTN in patients with NIDDM. 相似文献
96.
R V Jayakumar A K Al-Aska N Subesinghe S G Wright 《Postgraduate medical journal》1988,64(748):118-120
We have reviewed the clinical presentation of 100 consecutive culture positive cases of brucellosis which came under our care during the last two years. Of these, six had atypical presentations and but for the routine practice of sending blood for brucella culture, the diagnosis would have been missed. The unusual presentations included a 19 year old boy presenting as an acute abdomen ending in laparotomy, a 52 year old man presenting with a psoas abscess, a 29 year old woman presenting with a transient perinephric mass, a 75 year old man with an acute flare up of his osteoarthritis, a 65 year old diabetic man presenting in an insulin-resistant diabetic state and a 35 year old man presenting with a cauda equina syndrome. 相似文献
97.
S W Wright R R Harris J S Kerr A M Green D J Pinto E M Bruin R J Collins R L Dorow L R Mantegna S R Sherk 《Journal of medicinal chemistry》1992,35(22):4061-4068
Vinylogous hydroxamic acids (3-(N-hydroxy-N-alkylamino)-2-propen-1-ones, VHA) were prepared as antiinflammatory agents. The synthesis, chemical properties, and in vitro biological activities of these relatively unexplored compounds are described. The VHAs were prepared by condensation of the appropriate N-substituted hydroxylamine with any of the three reagents: a 1,3-dicarbonyl compound (method A); a vinylogous amide (method B); or an alkynone (method C). The VHAs exist as one or more tautomers in solution with the relative proportions of each being dependent upon the structure of the VHA, solvent, and pH. VHAs undergo some of the typical reactions of hydroxamic acids as well as those of vinylogous amides. VHAs are active as inhibitors of 5-lipoxygenase and of IL-1 biosynthesis in vitro, which do not inhibit other enzymes of the arachidonic acid cascade. They have been shown by ESR studies to bring about inhibition of soybean type 1 15-lipoxygenase by reduction of the active site iron. 相似文献
98.
Twenty-two adult patients with uncontrolled epilepsy and severe learning difficulties were included in an open study of vigabatrin. Patients were all in residential care and had experienced at least 12 seizures during the previous 12 months despite all attempts to optimize antiepileptic drug (AED) treatment. Following a 4 month baseline period, vigabatrin 500 mg twice daily was added to the current AED treatment and the dose increased according to response, up to a maximum of 4 g/day. Ten patients achieved a reduction in seizure frequency of more than 50% during this 4 month dose titration phase. Two patients had no seizures during the baseline period. For the 30 patients with seizures during the baseline period the median improvement in seizure frequency with the addition of vigabatrin was 49% (P = 0.014). The response rate was higher for patients with partial seizures than for those with generalized seizures. Ten patients continued with vigabatrin while the dose of one of their other AEDs was gradually reduced and successfully withdrawn in three patients. Adverse events were reported in 20 patients during the 64 week study period. The most frequently reported events were sedation (8 patients), aggression (4 patients), agitation (3 patients) and ataxia (3 patients). No patients were withdrawn from the study as a consequence of adverse events. Vigabatrin was therefore an effective add-on therapy in 45% of these difficult-to-treat patients and allowed reduction of other AED treatment in a small number. 相似文献
99.
Self-expanding endovascular graft: an experimental study in dogs 总被引:2,自引:0,他引:2
T Yoshioka K C Wright S Wallace D D Lawrence C Gianturco 《AJR. American journal of roentgenology》1988,151(4):673-676
An arterial endovascular graft was constructed by wrapping an expandable nylon mesh around a framework of Gianturco self-expanding metallic stents. The devices were passed through a 12-French Teflon catheter and positioned in the normal abdominal aorta of five dogs, two of which also had a device placed in an external iliac artery. At follow-up (1-6 months), all grafts remained patent, even though slight luminal narrowing due to neointimal encasement was noted. Histologically, all grafts were covered by neointimal proliferation at the time of removal. The graft material expanded with the stents, resulting in a tight fit between the graft and the vessel wall. Side branches narrowed but remained open because of the size of the nylon mesh. No migration of the grafts equipped with a barbed lead stent was noted. Expandable nylon mesh can be used as an endovascular graft material when wrapped around a framework of self-expanding stents. The resulting device can be easily delivered via transcatheter techniques, and once placed in a vessel, the nylon acts as a support for neointimal encasement, which forms a new vascular lumen. 相似文献
100.
After observing an association between vitamin A deficiency and otitis media among children in Micronesia, we sought to develop an animal model for vitamin A-deficiency-induced otitis media. Thirty juvenile guinea pigs were screened for absence for otitis and then divided into two groups. The experimental group was placed on a vitamin A-free diet, whereas control animals were fed a standard formula. The animals were followed by means of otologic examination and serum retinol determinations. When experimental animals demonstrated vitamin A deficiency, they were killed along with one control and temporal bones were harvested and prepared for histologic examination. None of the 15 controls demonstrated middle ear abnormalities. In the experimental group, 77% of temporal bones showed middle ear pathology consisting of either of subepithelial edema (27%) or frank otitis media (50%). These results indicate that the guinea pig is a suitable species for study of otitis media in association with vitamin A deficiency. We postulate that eustachian tube dysfunction is the primary mechanism for inducing middle ear inflammation in this animal model. 相似文献