首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2494篇
  免费   133篇
  国内免费   16篇
耳鼻咽喉   33篇
儿科学   97篇
妇产科学   64篇
基础医学   197篇
口腔科学   102篇
临床医学   234篇
内科学   482篇
皮肤病学   43篇
神经病学   200篇
特种医学   111篇
外国民族医学   1篇
外科学   510篇
综合类   78篇
预防医学   142篇
眼科学   60篇
药学   159篇
中国医学   16篇
肿瘤学   114篇
  2023年   22篇
  2022年   31篇
  2021年   71篇
  2020年   54篇
  2019年   62篇
  2018年   65篇
  2017年   46篇
  2016年   70篇
  2015年   61篇
  2014年   81篇
  2013年   129篇
  2012年   145篇
  2011年   163篇
  2010年   99篇
  2009年   82篇
  2008年   139篇
  2007年   151篇
  2006年   161篇
  2005年   161篇
  2004年   140篇
  2003年   112篇
  2002年   111篇
  2001年   70篇
  2000年   70篇
  1999年   65篇
  1998年   16篇
  1997年   26篇
  1996年   28篇
  1995年   13篇
  1994年   11篇
  1993年   8篇
  1992年   11篇
  1991年   14篇
  1990年   17篇
  1989年   9篇
  1988年   9篇
  1987年   8篇
  1986年   12篇
  1985年   13篇
  1984年   9篇
  1983年   6篇
  1980年   4篇
  1978年   7篇
  1975年   4篇
  1974年   3篇
  1972年   5篇
  1971年   6篇
  1970年   4篇
  1969年   9篇
  1967年   4篇
排序方式: 共有2643条查询结果,搜索用时 31 毫秒
1.
Abdominal Radiology - Metastatic involvement of the ovaries is not rare. The most common tumor types metastasizing to the ovaries, from non-gynecological organs, are breast, colorectal, gastric,...  相似文献   
2.
3.
我院自1984~1989年采用硅橡胶涤纶丝网颅骨成型片修补颅骨缺损116例,随访6月~4年,疗效满意。对颅骨修补的适应症作了讨论。减少手术创伤、预防术后感染,是保证手术成功的关键。  相似文献   
4.
Insulin deficiency is known to be associated with a state of increased muscle protein breakdown; this process is mediated by the ubiquitin-proteasome pathway. Convincing in vitro data are further supported by extensive studies in humans with insulin deprivation and are further substantiated by reversal of muscle protein breakdown with insulin treatment. In patients with end-stage renal disease (ESRD) and diabetes mellitus (DM), muscle protein breakdown is enhanced in both acute and chronic conditions. Recent data also point to the potential protein catabolic effects of insulin resistance combined with insulin deficiency. Because ESRD is associated with a state of insulin resistance, uremic muscle wasting may also be mediated by this pathway.  相似文献   
5.
OBJECTIVE: Radial arteries are increasingly used as conduits for coronary artery bypass grafts, but perioperative graft vasospasm remains a concern. In vitro testing has demonstrated the efficacy of phenoxybenzamine and verapamil/nitroglycerin as topical antispasmodic agents, but their duration of action in vivo is unknown. Using an in vivo mouse model, we measured their duration of action in functioning vascular grafts, and compared this to their in vitro duration of action in ungrafted vascular segments. METHODS: Two millimetre mouse aortic segments (C57/BL6) were incubated with phenoxybenzamine, verapamil/nitroglycerin, or buffer (controls) for 15 min in organ chambers. Isometric tension responses to phenylephrine and prostaglandin F2alpha were measured at 0, 2, 6 and 12 h post-incubation. In parallel, 36 murine infrarenal aortic interposition grafts (2 mm) were performed. Twelve grafts were pre-treated (15 min) with phenoxybenzamine, 12 with verapamil/nitroglycerin and 12 remained untreated (controls). Isometric tension responses to the same agonists were measured in grafts harvested 2, 6, 13 and 23 h after surgery. RESULTS: Phenoxybenzamine prevented alpha-adrenergic vasoconstriction for up to 16 h in vivo (grafts), and 12h in vitro (ungrafted segments). Verapamil/nitroglycerin was effective for at least 2 h in vitro, but did not prevent vasoconstriction after 2 h in vivo. CONCLUSIONS: The mouse model appears to be a useful technique for assessing the pharmacological properties of antispasmodic agents in vivo. Phenoxybenzamine has an extended action in arterial grafts in vivo. Verapamil/nitroglycerin is short-lived in vivo but lasts longer in vitro. Measurements of antispasmodic duration of action in vitro should be interpreted with caution.  相似文献   
6.
OBJECTIVE: To determine physical activity patterns in chronic hemodialysis patients with a specific emphasis on the difference between dialysis and nondialysis days. Design A cross-sectional single-center study. SETTING: Vanderbilt University Outpatient Dialysis Unit. PATIENTS: Twenty current chronic hemodialysis patients: 10 male, 10 female; 15 black, 5 white; mean age, 50.1 +/- 9.9 years; height, 164.5 +/- 10.9 cm; weight, 82.5 +/- 15.4 kg; length on dialysis, 57.3 +/- 45.3 months. METHODS: Minute-by-minute physical activity was assessed over a 7-day period using a triaxial accelerometer, which consists of raw numbers or counts calculated by the 3 axes of the accelerometer (PA counts). PA counts were extrapolated on a daily and hourly basis. Physical functioning tests included: sit-to-stand, 6-minute walk, and 1-repetition maximal leg press exercise. Laboratory values for serum concentrations of albumin, prealbumin, C-reactive protein, and cholesterol were also collected. MAIN OUTCOME MEASURE: PA counts. RESULTS: Total PA counts were significantly lower on dialysis days when compared with nondialysis days (128,279 +/- 74,009 versus 168,744 +/- 95,168, respectively, P = .025). The average PA counts during the 4-hour dialysis time period were significantly lower on dialysis days when compared with nondialysis days (3,086 +/- 3,749 versus 11,070 +/- 7,695, respectively, P = .001). At postdialysis hours 1 and 2, PA counts on dialysis days were significantly higher than on nondialysis days (11,410 +/- 5,340 versus 9,082 +/- 6,646, P = .008, and 14,048 +/- 9,728 versus 8,662 +/- 6,433, P = .016, respectively). By postdialysis hour 4, PA counts on dialysis days had significantly decreased when compared with nondialysis days (6,068 +/- 6,268 versus 10,512 +/- 7,420 PA counts, P = .01, respectively). From postdialysis hours 5 to 20, there was no significant difference in PA counts between dialysis and nondialysis days. CONCLUSION: This study shows that physical activity is lower on dialysis days when compared with nondialysis days, and this decrease is caused by the lack of activity during the 4-hour hemodialysis procedure. New behavior modification strategies involving physical activity, both during hemodialysis and on nondialysis days, must be examined in this patient population.  相似文献   
7.
C1-Cx revisited: intramolecular synergism in a cellulase.   总被引:4,自引:0,他引:4       下载免费PDF全文
Endoglucanase A (CenA) from the bacterium Cellulomonas fimi is composed of a catalytic domain and a nonhydrolytic cellulose-binding domain that can function independently. The individual domains interact synergistically in the disruption and hydrolysis of cellulose fibers. This intramolecular synergism is distinct from the well-known intermolecular synergism between individual cellulases. The catalytic domain corresponds to the hydrolytic Cx system and the cellulose-binding domain corresponds to the nonhydrolytic C1 system postulated by Reese et al. [Reese, E. T., Sui, R. G. H. & Levinson, H. S. (1950) J. Bacteriol. 59, 485-497] to be required for the hydrolysis of cellulose.  相似文献   
8.
The results of percutaneous radiofrequency rhizotomy of lumbar spinal facets in 46 patients followed at least three months (mean 15 months) are reported and compared with those reported previously. Satisfactory pain relief three months after the procedure was achieved in 36.4 percent of patients without operations and in 41.7 percent of patients with operations other than fusion.No patient had previously undergone fusion.Treatment of low-back pain by using radio-frequency thermocoagulation of spinal facets is a simple, safe, and well-tolerated procedure. It can be used to relief of pain in spite of decreasing rates of success within the follow-up period.  相似文献   
9.
Chlamydial infections and male infertility   总被引:3,自引:0,他引:3  
Chlamydial infections may be difficult to diagnose due to the silent symptoms and difficulty in culturing. An infectious process may impair fertility by adversely affecting sperm functions, resulting in testicular damage or causing obstruction of the genital tract. In our study, we tried to find Chlamydial antigen by using EIA (Enzyme Immune Assay) and to compare the Ag(+) and Ag(−) groups according to semen parameters. Except for semen volume, we found significant differences in density, morphology, motility and viability (intervolume p>0.05, interdensity p<0.01, intermorphology p<0.001, intermotility p<0.001 and interviability p<0.001).  相似文献   
10.
Partial thickness burns (PTB) usually heal within 3 weeks. Prevention of infection and desiccation of the wounds are crucial for optimal healing. Early tangential excision of the burn eschar and allografting prevent deepening of the burns, and are therefore advocated for treatment with the best functional and aesthetic results. For superficial partial thickness burns (SPTB) conservative use of topical antimicrobial agents with frequent dressing changes are implemented. We compared the conservarive treatment for PTBs and SPTBs to grafting cryopreserved cadaveric allografts with no prior excision.

Twelve patients with flame PTB areas were allografted after mechanical debridement without excision of the burn wounds. The allografts were cadaveric skin cryopreserved by programmed freezing and stored at −180°C for 30–48 months. Matching burns for depth and area were treated with silver sulfadiazine (SSD) one to two times daily until healing or debridement and grafting were required.

It was found that 80 per cent of the cryopreserved allografts adhered well and 76 per cent of the treated areas healed within 21 days, whereas only 40 per cent of the SSD-treated burns healed within 21 days.

Partial thickness burns can be treated successfully with viable human allografts (cryopreserved cadaveric skin) with no prior surgical excision. The burn wounds heal well within 3 weeks. For deep partial thickness burns (DPTB) treatment with allografts has no advantage if they have not been previously excised.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号