全文获取类型
收费全文 | 1179篇 |
免费 | 114篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 112篇 |
妇产科学 | 20篇 |
基础医学 | 125篇 |
口腔科学 | 30篇 |
临床医学 | 138篇 |
内科学 | 302篇 |
皮肤病学 | 24篇 |
神经病学 | 36篇 |
特种医学 | 89篇 |
外科学 | 122篇 |
综合类 | 29篇 |
一般理论 | 1篇 |
预防医学 | 129篇 |
眼科学 | 2篇 |
药学 | 102篇 |
肿瘤学 | 48篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 13篇 |
2019年 | 15篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 27篇 |
2013年 | 46篇 |
2012年 | 63篇 |
2011年 | 51篇 |
2010年 | 37篇 |
2009年 | 34篇 |
2008年 | 48篇 |
2007年 | 54篇 |
2006年 | 47篇 |
2005年 | 40篇 |
2004年 | 39篇 |
2003年 | 42篇 |
2002年 | 30篇 |
2001年 | 34篇 |
2000年 | 51篇 |
1999年 | 44篇 |
1998年 | 40篇 |
1997年 | 33篇 |
1996年 | 31篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 16篇 |
1992年 | 27篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 22篇 |
1988年 | 31篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 24篇 |
1984年 | 19篇 |
1983年 | 19篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1970年 | 6篇 |
1967年 | 4篇 |
排序方式: 共有1312条查询结果,搜索用时 46 毫秒
1.
2.
Adam J. Singer MD Steve A. McClain MD Alexander Romanov DVM Jean Rooney BS Tom Zimmerman DVM 《Academic emergency medicine》2007,14(12):1125-1129
Objectives Cutaneous burns are dynamic injuries with a central zone of necrosis surrounded by a zone of ischemia. Conversion of this ischemic zone to full necrosis over the days following injury is due in part to highly reactive oxygen radicals. Curcumin is a component of the Oriental spice turmeric that has been shown to have antioxidant and antiapoptotic properties. The authors hypothesized that treatment of burns with curcumin would reduce the conversion of the ischemic zone to full necrosis. Methods This was a randomized controlled experiment. Twenty Sprague‐Dawley rats were used. Two burns were created on each animal's dorsum using a brass comb with four rectangular prongs preheated in boiling water and applied for 30 seconds, resulting in four rectangular 10 × 20–mm full‐thickness burns separated by three 5 × 20–mm unburned interspaces (zone of ischemia). Animals were randomized to curcumin or vehicle by oral gavage 30 minutes before injury and at 24, 48, and 72 hours after injury. Wounds were observed at one, two, and three days after injury for visual evidence of necrosis in the unburned interspaces. Full‐thickness biopsy specimens from the interspaces were evaluated with hematoxylin and eosin staining seven days after injury for evidence of necrosis. The percentage of interspaces that progressed to necrosis was compared with chi‐square tests. Results Forty comb burns with 120 unburned interspaces were created, evenly distributed between curcumin and vehicle alone. The percentage of interspaces that progressed to full‐thickness necrosis at one, two, three, and seven days after injury in the curcumin and vehicle groups were 30% versus 63% (p = 0.003), 30% versus 70% (p < 0.001), 63% versus 95% (p = 0.02), and 63% versus 95% (p = 0.02), respectively. Conclusions Pretreatment of rats with oral curcumin followed by once‐daily oral treatment for three days reduced the percentage of unburned skin interspaces that progressed to full necrosis. 相似文献
3.
4.
Trevor McClain Griffitts Chad Patrick Collins Patrick Charles Collins 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2005,100(5):e81-e84
OBJECTIVE: This article examines the success of mini-dental implants (MDI'S) by assessing four subjective measures of patient satisfaction for MDI's in the edentulous maxilla and mandible: comfort, retention, chewing ability and speaking ability. Success rates, surgical techniques, and financial advantages of the MDI's are reviewed. STUDY DESIGN: Thirty consecutive patients received four MDI's between the mental foramen of the mandible from 9/18/2003 to 10/22/2004. Questionnaires were sent to all thirty patients an average of 5 months postoperatively. The patients ranked comfort, retention, chewing ability, and speaking ability from 1 to 10 (1=poor and 10=excellent). RESULTS: A total of 116 MDI's were placed in 13 months and 113 remain stable for a 97.4% implant success rate. Pre-operatively patients rated their retention at 1.7+/-0.42 and post-operatively at 9.6+/-0.37, for a difference of 7.9 (p=3.6-19). Comfort was the next greatest improvement, with a pre-operative rating of 2.2+/-0.63 and a post-operative rating of 9.4+/-0.45, for a difference of 7.2 (p=3.5-15). Chewing ability also improved, with a difference of 7.0 (p=2.9e-16). In the final category of speaking ability, the pre-operative to post-operative difference was 3.2 (p=1.1e-5). CONCLUSION: MDI's are a highly successful implant option for patients with poor tolerance to maxillary and mandibular prosthesis. The implants are relatively affordable and overall patient satisfaction is excellent. 相似文献
5.
Altered gastric emptying in the head-injured patient: relationship to feeding intolerance 总被引:12,自引:0,他引:12
L Ott B Young R Phillips C McClain L Adams R Dempsey P Tibbs U Y Ryo 《Journal of neurosurgery》1991,74(5):738-742
Most patients with moderate to severe head injury initially do not tolerate enteral feedings postinjury. This intolerance is more prolonged than that found in patients suffering other types of trauma. The authors prospectively evaluated 12 patients with moderate to severe head injury (Glasgow Coma Scale score between 4 and 10) throughout their hospitalization for liquid gastric emptying as a possible mechanism for intolerance to enteral feeding. During Week 1, the majority of patients displayed a delay in gastric emptying. Patients also displayed an abnormal biphasic response (gastric emptying faster than normal during the early stage but prolonged later). By Week 2, many patients still had delayed and abnormal biphasic responses to gastric emptying. By Week 3, an improvement was observed with the majority of patients exhibiting rapid gastric emptying, but delays and abnormal biphasic responses were still seen. Patients who initially had rapid or normal gastric emptying tolerated full-strength full-rate feedings significantly earlier compared with those who experienced delayed gastric emptying (8.5 +/- 0.5 days vs. 13.7 +/- 3.2 days, p less than 0.001). All patients tolerated full-strength full-rate feedings by Day 16 postinjury (range 7 to 16 days) except the two patients who displayed delayed gastric emptying for prolonged periods of time (mean 25 days). This is the first study to longitudinally evaluate gastric emptying following head injury. The authors suggest that patients with moderate to severe head injury often experience alterations in gastric emptying which may affect their ability to tolerate enteral feedings. 相似文献
6.
Ben F. Brammell J. Scott McClain James T. Oris David J. Price Wesley J. Birge Adria A. Elskus 《Archives of environmental contamination and toxicology》2010,58(3):772-782
It has become increasingly apparent that resident fish can develop resistance to chemicals in their environment, thus compromising
their usefulness as sentinels of site-specific pollution. By using a stream system whose resident fish appear to have developed
pollutant resistance (Brammell et al., Mar Environ Res 58:251–255, 2005), we tested the hypothesis that the pollutant-inducible biomarker, cytochrome P4501A (CYP1A), as measured in field-caged
juvenile rainbow trout (Oncorhynchus mykiss), would reflect relative pollution differences between reference and polychlorinated biphenyl (PCB)-contaminated sites. Trout
were caged in the Town Branch/Mud River system (Logan County, KY), a stream system undergoing remediation for PCBs. Fish were
held in remediated (Town Branch), unremeditated (Mud River), and reference sites for 2 weeks during spring 2002. At the end
of this period, gill and hepatic CYP1A expression were measured. To evaluate the relative PCB exposure of caged trout and
provide a reference point against which to calibrate CYP1A response, PCB levels were quantified in sediments from each site.
Hepatic CYP1A expression in caged trout clearly detected the presence of PCBs in the Town Branch/Mud River stream system.
Sediment PCB levels and hepatic CYP1A expression in caged trout produced identical pollution rankings for the study sites.
Gill CYP1A expression, although suggestive of site differences, was not statistically different among sites. Unlike resident
fish, which failed to show site differences in hepatic CYP1A expression in this waterway (Brammell et al. 2005), caged fish proved to be a sensitive discriminator of relative PCB contamination in this system. In summary, we determined
that CYP1A expression in caged fish reflected relative in situ pollutant exposure. The exposure paradigm confirmed that 2 weeks
was a sufficient caging period for evaluating CYP1A response in this species at these temperatures (13–19°C). In addition,
these studies demonstrate that tissue-specific CYP1A expression can provide insights into likely routes of exposure. We conclude
that CYP1A expression in caged trout is a reliable and inexpensive first-pass determination of relative environmental pollutant
exposure and bioavailability in aqueous systems. 相似文献
7.
8.
Provocation of pulmonary vascular endothelial injury in rabbits by human recombinant interleukin-1 beta. 总被引:6,自引:2,他引:6 下载免费PDF全文
Interleukin-1 (IL-1) mediates components of the acute-phase response, stimulates granulocyte metabolism, and induces endothelial cell surface changes. We studied the effects of human recombinant IL-1 beta (rIL-1 beta) or rIL-1 alpha on circulating granulocytes, their sequestration within the pulmonary microvasculature, pulmonary edema formation, and changes in pulmonary vascular permeability to 125I-labeled albumin. rIL-1 beta administration induced significant (P less than 0.03) but transient granulocytopenia followed by significant (P less than 0.04) neutrophilia and significant (P less than 0.04) pulmonary leukostasis compared with saline-infused rabbits. Rabbits preinfused with 125I-labeled rabbit serum albumin and administered saline, rIL-1 beta, or rIL-1 alpha were sacrificed, and lung wet/dry weight ratios and bronchoalveolar lavage fluid and plasma 125I activities determined. Both rIL-1 beta and rIL-1 alpha increased lung wet/dry weight ratios (P less than 0.025 and P less than 0.01, respectively) compared with saline controls. rIL-1 beta increased bronchoalveolar lavage fluid/plasma 125I radioactivity ratios (P less than 0.025). Electron microscopic analysis of lung sections obtained from rIL-1 beta-infused animals demonstrated endothelial injury, perivascular edema, and extravasation of an ultrastructural permeability tracer. The observation that human rIL-1 can evoke acute pulmonary vascular endothelial injury and lung edema in rabbits supports the hypothesis that IL-1 may play a role in the pathogenesis of the adult respiratory distress syndrome. 相似文献
9.
Evaluation of three substitutes for Percoll in sperm isolation by density gradient centrifugation 总被引:9,自引:4,他引:9
Silane-coated silica particle solutions (ISolate(TM) and PureSperm)TM)) and
iodixanol (OptiPrep(TM)) were compared to polyvinylpyrrolidone (PVP)-coated
silica particles (Percoll(TM)) in their efficacy to recover spermatozoa by
gradient centrifugation for use in assisted reproductive procedures.
Efficacy was assessed in terms of percentages of sperm recovery, sperm
vitality and motility, normal sperm morphology and normal sperm chromatin
condensation. No significant difference was found in the recovery of
spermatozoa for men with both normal sperm counts and oligozoospermia,
between PVP-coated and silane-coated particle solutions. Iodixanol had
significantly lower sperm recovery compared to the other products. Sperm
vitality, progressive motility, normal morphology and normal chromatin
condensation did not differ significantly between any of the sperm
isolation products.
相似文献
10.
Ribosomal binding sites on poliovirus RNA 总被引:3,自引:0,他引:3
Eucaryotic ribosome binding sites on type 1 poliovirus RNA were obtained by isolation of T1 RNase-resistant RNA fragments from 80 S ribosomes that had been bound under conditions specific for initiation of translation and prevented from translocation with sparsomycin. The fragments were analyzed by two-dimensional polyacrylamide gel electrophoresis. Three ribosome-protected (RP) oligonucleotides and several non-ribosomal-protein-protected (NP) oligonucletides were analyzed. Secondary T1 digestion of the RP fragments revealed that at least three separate species existed. By comparison of these secondary digests to T1 digests of RNaseIII fragments mapped on the polio RNA, and by electron microscopic observation of ribosomes bound to polio RNA, preferred ribosome binding sites were localized to near 115 bases from the 5′ end, just to the 3′ side of midgenome, and 780 bases from the 3′ end. 相似文献