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   49456篇
  免费   3001篇
  国内免费   240篇
耳鼻咽喉   500篇
儿科学   928篇
妇产科学   629篇
基础医学   6479篇
口腔科学   1080篇
临床医学   5190篇
内科学   10945篇
皮肤病学   995篇
神经病学   5687篇
特种医学   2501篇
外科学   8257篇
综合类   295篇
一般理论   13篇
预防医学   2264篇
眼科学   651篇
药学   2948篇
中国医学   69篇
肿瘤学   3266篇
  2023年   431篇
  2022年   692篇
  2021年   1415篇
  2020年   840篇
  2019年   1271篇
  2018年   1438篇
  2017年   1129篇
  2016年   1343篇
  2015年   1557篇
  2014年   1971篇
  2013年   2429篇
  2012年   3915篇
  2011年   3951篇
  2010年   2352篇
  2009年   2117篇
  2008年   3365篇
  2007年   3446篇
  2006年   3180篇
  2005年   3135篇
  2004年   2772篇
  2003年   2657篇
  2002年   2410篇
  2001年   459篇
  2000年   349篇
  1999年   426篇
  1998年   479篇
  1997年   365篇
  1996年   287篇
  1995年   227篇
  1994年   220篇
  1993年   169篇
  1992年   144篇
  1991年   141篇
  1990年   108篇
  1989年   94篇
  1988年   99篇
  1987年   63篇
  1986年   79篇
  1985年   75篇
  1984年   105篇
  1983年   81篇
  1982年   78篇
  1981年   58篇
  1980年   56篇
  1979年   52篇
  1978年   50篇
  1977年   52篇
  1976年   47篇
  1975年   52篇
  1974年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
In 2003 through 2005, the California Statewide Area Health Education Centers (AHEC) Program developed an educational delivery system, through partnerships with six AHECs and state organizations concerned with emergency preparedness, to train for public health emergency preparedness the health professionals who practice primarily in the state's medically underserved areas. Four educational modules--General Emergency Preparedness, Bioterrorism, Chemical and Radiologic Agents, and Emerging Infections--were developed and delivered by a trained, multidisciplinary, community-based faculty. The authors discuss the organization, partnerships, curriculum, faculty, characteristics of trainees, outcomes of the program, effects for AHECs, and the evaluation used to commit the organization and program process to the intended program objectives during the two-year period. Over 9,000 health professionals attended one or more of the 462 educational presentations. Approximately one third of attendees were physicians, and 82% of the learners were from sites that typically care for the underserved. Important to the success of the program (which still continues in a revised form) were the types of partnerships, an orientation of the curriculum to all-hazards disaster preparedness, the delivery of educational sessions at clinical sites, and the increased capacities of community AHECs to facilitate continuing professional education. The challenges were the diminished role of a key partner organization, uncertainties within the funding agency, and the widespread geographic area to address.  相似文献   
62.
63.
BACKGROUND: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys. In contrast to haemoperfusion, synthetic perfusion media can be standardized and can prevent the initiation of blood-mediated reperfusion reactions. Thus, an additional aim was to determine whether blood could be replaced by synthetic cell-free perfusion solutions. METHODS: Canine kidneys (n = 30) were harvested from donors euthanized in veterinary practices for causes unrelated to the present study. The kidneys were isolated and perfused with autologous blood or cell-free synthetic electrolyte buffer (Tyrode solution). During perfusion, we monitored renal perfusate flow (RPF), glomerular filtration rate (GFR), electrolyte and glucose reabsorption, oxygen consumption and urine concentration. RESULTS: Changes in perfusion medium did not affect the RPF. In contrast, GFR, urine concentration and oxygen consumption were significantly higher, whereas fractional excretion of sodium and glucose were significantly lower in blood- than in Tyrode-perfused kidneys. CONCLUSIONS: This system offers a simple model for studying whole-organ functional alterations after acute renal ischaemia. Renal function indicators were below values reported during in vivo physiological conditions. These functions were better conserved when kidneys were perfused with autologous blood than with Tyrode.  相似文献   
64.
Hypothesis: Does occupational exposure to solvents in combination with alcohol intake give rise to acquired color vision defects? Method: A total of 138 individuals exposed to solvents (toluene, xylene, trichloroethylene, tetrachloroethylene) were examined using Lanthony’s D-15 test and compared with 100 nonexposed controls. The extent of color vision loss was quantitatively assessed based on Bowman’s color confusion index (CCI). A cumulative exposure index was calculated from the hours of exposure per day and the years of exposure. In 30 persons who were exposed to trichloroethylene and tetrachloroethylene, urinary trichloroacetic acid was assessed as a parameter of exposure. Alcohol intake was calculated as based on interviews of patients in grams of ethyl alcohol per week. Results: Individuals who consumed more than 250 g alcohol/week and were simultaneously exposed to solvents showed a significantly elevated CCI (P = 0.0044). No significant correlation emerged between trichloroacetid acid excretion in the urine or the cumulative exposure index and the CCI. Conclusion: The combination of alcohol intake and occupational exposure to solvents discloses the risk of acquired subclinical color vision defects.  相似文献   
65.
Summary: Purpose : As shown previously, when temporal lobe complex partial seizures (TLCPS) originate from the language dominant hemisphere, patients cannot read a test phrase correctly within 60 s of the end of the ictal discharge. We wished to assess whether postictal language testing results discordant with this pattern identified patients with non-left (right hemisphere or mixed) language dominance.
Methods : Since 1988, all patients undergoing video/EEG monitoring at our institution have been given a test phrase to read aloud as soon as a seizure is detected. Inclusion criteria for this study were (a) postictal language testing within 60 s of seizure end for at least one TLCPS, (b) >90% seizure reduction after anterior temporal lobectomy with 2-year minimum follow- follow- up, and (c) language localization by either intracarotid amobarbital test (IAT) or direct electrical stimulation of left hemisphere cortex.
Results : Two hundred twenty-four seizures in 64 patients were analyzed. Discordant postictal language patterns were noted in 10 of 11 patients with IAT documented non-left language dominance and in 15 of 53 with left dominance (p = 0.006; sensitivity 90.9%, specificity 71.7%).
Conclusions : Postictal language testing accurately identifies patients with non-left language dominance and may be useful in selecting appropriate patients for IAT.  相似文献   
66.
67.
Plasmids carrying type I or II sulfonamide-resistance (Sur) genes were evaluated for their effect on synergy between trimethoprim (Tmp) and sulfamethoxyzole (Smx) in E. coli. Strain J53 containing each of three plasmids (R1, pSa, and R388) with the type I Sur gene displayed a synergistic response to Tmp/Smx; strain LE392 containing a plasmid (RSF1010) with the type II Sur gene displayed no synergy. The difference in synergy between type I and type II Sur genes might be explained by the difference in amount of resistant enzyme produced.  相似文献   
68.
69.
Details of the cellular and biochemical mechanisms involved in focal destruction of bone at sites of tumor osteolysis are unknown. It has been shown that tumors from sarcoma (2472) cell lines induce focal osteolysis in mice by stimulating formation and activation of osteoclasts. In this report, the influence of 2472 tumors on the skeletons of osteoclast-deficient animals (op/op) was studied. After op/op femora had been inoculated with 2472 cells, tumors developed and focal osteolysis occurred. There were more osteoclasts per histologic section in sham-injected femora (19 ± 5) than in tumor-bearing femora (412 ± 129) (p < 0.05). The size of the osteoclasts also increased from 304 ± 81 μm2 in sham-injected limbs to 407 ± 62 μm2 in tumor-bearing limbs (p < 0.001). Conditioned media from 2472 op/op tumor explants contained macrophage colony-stimulating factor. A deficiency of osteoclasts in op/op mice is the result of the absence of this factor; therefore, these data introduce the possibility that macrophage colony-stimulating factor derived from 2472 tumor may be responsible for directing osteoclast-mediated osteolysis at sites of the tumor.  相似文献   
70.
A comparison study of dynamic visual acuity (DVA) was conducted using samples of nonathletic college students and college baseball players. The experimental population consisted of 17 male baseball players ranging in age from 19-24 years. The control population was made up of 25 male graduate students ranging in age from 23-29 years. Subjects reported the direction of a 20/25 "Landolt C" target exhibiting uniform angular motion produced by a projection system. Angular target velocities between 10 deg/sec and 110 deg/sec with an exposure time of 400 ms were used. The results showed a statistically significant difference between the two groups' DVA. The mean DVA for the baseball players was 82.35 deg/sec and 69.90 deg/sec for the control group.  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