全文获取类型
收费全文 | 4373篇 |
免费 | 349篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 55篇 |
儿科学 | 104篇 |
妇产科学 | 97篇 |
基础医学 | 631篇 |
口腔科学 | 46篇 |
临床医学 | 623篇 |
内科学 | 745篇 |
皮肤病学 | 37篇 |
神经病学 | 491篇 |
特种医学 | 148篇 |
外科学 | 462篇 |
综合类 | 107篇 |
一般理论 | 5篇 |
预防医学 | 507篇 |
眼科学 | 67篇 |
药学 | 328篇 |
中国医学 | 6篇 |
肿瘤学 | 272篇 |
出版年
2023年 | 23篇 |
2022年 | 22篇 |
2021年 | 84篇 |
2020年 | 41篇 |
2019年 | 83篇 |
2018年 | 91篇 |
2017年 | 64篇 |
2016年 | 69篇 |
2015年 | 77篇 |
2014年 | 115篇 |
2013年 | 154篇 |
2012年 | 237篇 |
2011年 | 255篇 |
2010年 | 130篇 |
2009年 | 110篇 |
2008年 | 221篇 |
2007年 | 237篇 |
2006年 | 210篇 |
2005年 | 220篇 |
2004年 | 219篇 |
2003年 | 181篇 |
2002年 | 171篇 |
2001年 | 135篇 |
2000年 | 123篇 |
1999年 | 133篇 |
1998年 | 37篇 |
1997年 | 45篇 |
1996年 | 30篇 |
1995年 | 35篇 |
1994年 | 32篇 |
1992年 | 93篇 |
1991年 | 85篇 |
1990年 | 76篇 |
1989年 | 64篇 |
1988年 | 62篇 |
1987年 | 58篇 |
1986年 | 63篇 |
1985年 | 69篇 |
1984年 | 36篇 |
1983年 | 42篇 |
1982年 | 24篇 |
1981年 | 24篇 |
1980年 | 34篇 |
1979年 | 38篇 |
1978年 | 31篇 |
1976年 | 21篇 |
1975年 | 23篇 |
1974年 | 32篇 |
1972年 | 31篇 |
1970年 | 25篇 |
排序方式: 共有4731条查询结果,搜索用时 421 毫秒
71.
72.
Expression of proneural and neurogenic genes in the embryonic mammalian vestibular system 总被引:3,自引:0,他引:3
Shailam R Lanford PJ Dolinsky CM Norton CR Gridley T Kelley MW 《Journal of neurocytology》1999,28(10-11):809-819
73.
van Kammen DP McAllister-Sistilli CG Kelley ME Gurklis JA Yao JK 《Psychiatry research》1999,87(2-3):129-136
Interleukin 6 (IL-6) levels have been shown to be increased in a number of autoimmune disorders and have recently been shown to be elevated in the serum of schizophrenic patients. Given the involvement of the CNS in schizophrenia, levels of interleukin-6 in the CSF are also of interest. Thus, we examined levels of both CSF and serum IL-6 concomitantly to determine if these levels were different from control values. In addition, we examined these measures in patients both on and off antipsychotic drugs to determine if any medication or exacerbation effects may account for the difference from controls. CSF IL-6 was measured by ELISA in 61 drug-free male schizophrenic (DSM-IIIR) patients and 25 well-screened healthy male control subjects. Serum IL-6 was measured in 43 of the 61 patients, and in 16 control subjects. Serum IL-6 was significantly higher in the schizophrenic patients compared to control subjects. CSF IL-6 was also higher in the patients, but the difference was not statistically significant. Paired data showed no medication or exacerbation effects on CSF IL-6, but plasma IL-6 significantly decreased in patients that experienced an exacerbation after medication withdrawal. The results indicate that IL-6 levels may be altered in schizophrenia. The relative decrease in exacerbated patients following haloperidol withdrawal may be indicative of a compensatory response of plasma IL-6 levels to relapse. 相似文献
74.
Both sexes of C57BL/6 (C57) mice consumed substantial quantities of ethanol without food or water deprivation whether access was continuous or limited. Food deprivation increased the amount of ethanol consumed, and the amount consumed depended upon when the animals were tested with reference to their daily food allotment. Ethanol consumption was greater if the mice were tested postprandially, high thirst motivation, rather than preprandially (approximately 10 vs. approximately 4.5 g/kg/30 min). Preference for ethanol over water, however, was greater when mice were under low thirst motivation (i.e., tested preprandially or with water available during the test). Compared to males, female mice consumed more of a high-ethanol concentration solution (10%) when access was continuous or limited to the first hour of the dark (active) phase of the circadian cycle. Also, in contrast to males, female mice exhibited increased ethanol consumption across days of drinking experience. Finally, although ethanol consumption under the food deprivation conditions of this experiment did not differ according to sex, females had higher blood ethanol concentrations than male C57 mice, a finding not previously reported for rodents but common to humans. 相似文献
75.
Asthma has a significant impact on U.S. military expenditures and readiness. Every year approximately 1,000 recruits are discharged for asthma during their first 6 months of service. This study was done to evaluate the practice of allowing some individuals with a history of asthma to enter military service (waiving). A survival analysis was performed to compare length of time until discharge and asthma-related failure for individuals waived for asthma (cases) and individuals not disqualified for asthma (controls). Cases were 587 recruit applicants initially disqualified who received waivers for asthma and accessed in the years 1995 to 1997. Controls were 1,761 matched enlisted recruits starting basic training in those years. No significant differences were found with respect to general attrition. The statistical differences for asthma-related hospitalization or discharge did not translate into practical differences. Waiving for asthma was not a significant occupational liability in terms of asthma-related hospitalization or early military attrition. 相似文献
76.
77.
David AC Leggett Kenneth A Miles Benjamin B Kelley 《Journal of Medical Imaging and Radiation Oncology》1998,42(4):335-340
Five cases of cerebral glioma are presented here that illustrate the benefit of functional CT imaging of blood-brain barrier permeability and cerebral blood volume. Functional CT uses Patlak analysis of a single location dynamic sequence to extract physiological information that is useful clinically in the assessment of cerebral gliomas. Functional CT offers distinct advantages over other functional modalities including clearer delineation of tumour, tumour grading, measurement of tumour activity and monitoring response to therapy. 相似文献
78.
For many years, the Randle glucose fatty acid cycle has been invoked to explain insulin resistance in skeletal muscle of patients with type 2 diabetes or obesity. Increased fat oxidation was hypothesized to reduce glucose metabolism. The results of a number of investigations have shown that artificially increasing fat oxidation by provision of excess lipid does decrease glucose oxidation in the whole body. However, results obtained with rodent or human systems that more directly examined muscle fuel selection have found that skeletal muscle in insulin resistance is accompanied by increased, rather than decreased, muscle glucose oxidation under basal conditions and decreased glucose oxidation under insulin-stimulated circumstances, producing a state of "metabolic inflexibility." Such a situation could contribute to the accumulation of triglyceride within the myocyte, as has been observed in insulin resistance. Recent knowledge of insulin receptor signaling indicates that the accumulation of lipid products in muscle can interfere with insulin signaling and produce insulin resistance. Therefore, although the Randle cycle is a valid physiological principle, it may not explain insulin resistance in skeletal muscle. 相似文献
79.
We report an unusual clinical presentation of Lyme carditis in a previously healthy 20-year-old black woman without any epidemiologic history of Lyme disease, fulminant in nature, involving a heart valve necessitating emergent mitral valve replacement, and requiring further surgical intervention because of the development of pericardial effusion and tamponade. A dilated right ventricle with normal contractility and severe tricuspid regurgitation with increase in the right atrial size diagnosed later remains under close surveillance. 相似文献
80.
Electrocardiographic ST-segment changes during acute, severe isovolemic hemodilution in humans 总被引:7,自引:0,他引:7
Leung JM Weiskopf RB Feiner J Hopf HW Kelley S Viele M Lieberman J Watson J Noorani M Pastor D Yeap H Ho R Toy P 《Anesthesiology》2000,93(4):1004-1010
BACKGROUND: Controversy exists regarding the lowest blood hemoglobin concentration that can be safely tolerated. The authors studied healthy resting humans to test the hypothesis that acute isovolemic reduction of blood hemoglobin concentration to 5 g/dl would produce an imbalance in myocardial oxygen supply and demand, resulting in myocardial ischemia. METHODS: Fifty-five conscious healthy human volunteers were studied. Isovolemic removal of aliquots of blood reduced blood hemoglobin concentration from 12.8 +/- 1.2 to 5.2 +/- 0.5 g/dl (mean +/- SD). Removed blood was replaced simultaneously with intravenous fluids to maintain constant isovolemia. Hemodynamics and arterial oxygen content (Cao2) were measured before and after removal of each aliquot of blood. Electrocardiographic (ECG) changes were monitored continuously using a Holter ECG recorder for detection of myocardial ischemia. RESULTS: During hemodilution, transient, reversible ST-segment depression developed in three subjects as seen on the electrocardiogram during hemodilution. These changes occurred at hemoglobin concentrations of 5-7 g/dl while the subjects were asymptomatic. Two of three subjects with ECG changes had significantly higher heart rates than those without ECG changes at the same hemoglobin concentrations. When evaluating the entire study period, the subjects who had ECG ST-segment changes had significantly higher maximum heart rates than those without ECG changes, despite having similar baseline values. CONCLUSION: With acute reduction of hemoglobin concentration to 5 g/dl, ECG ST-segment changes developed in 3 of 55 healthy conscious adults and were suggestive of, but not conclusive for, myocardial ischemia. The higher heart rates that developed during hemodilution may have contributed to the development of an imbalance between myocardial supply and demand resulting in ECG evidence of myocardial ischemia. However, these ECG changes appear to be benign because they were reversible and not accompanied by symptoms. 相似文献