全文获取类型
收费全文 | 3868篇 |
免费 | 211篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 127篇 |
妇产科学 | 47篇 |
基础医学 | 445篇 |
口腔科学 | 159篇 |
临床医学 | 324篇 |
内科学 | 1070篇 |
皮肤病学 | 208篇 |
神经病学 | 197篇 |
特种医学 | 321篇 |
外科学 | 308篇 |
综合类 | 74篇 |
预防医学 | 204篇 |
眼科学 | 58篇 |
药学 | 361篇 |
中国医学 | 5篇 |
肿瘤学 | 171篇 |
出版年
2021年 | 44篇 |
2019年 | 43篇 |
2018年 | 78篇 |
2017年 | 39篇 |
2016年 | 36篇 |
2015年 | 41篇 |
2014年 | 64篇 |
2013年 | 59篇 |
2012年 | 103篇 |
2011年 | 115篇 |
2010年 | 94篇 |
2009年 | 97篇 |
2008年 | 120篇 |
2007年 | 131篇 |
2006年 | 110篇 |
2005年 | 120篇 |
2004年 | 150篇 |
2003年 | 129篇 |
2002年 | 141篇 |
2001年 | 134篇 |
2000年 | 121篇 |
1999年 | 133篇 |
1998年 | 83篇 |
1997年 | 92篇 |
1996年 | 76篇 |
1995年 | 73篇 |
1994年 | 67篇 |
1993年 | 70篇 |
1992年 | 80篇 |
1991年 | 105篇 |
1990年 | 80篇 |
1989年 | 89篇 |
1988年 | 103篇 |
1987年 | 100篇 |
1986年 | 87篇 |
1985年 | 71篇 |
1984年 | 55篇 |
1983年 | 61篇 |
1982年 | 58篇 |
1981年 | 36篇 |
1980年 | 39篇 |
1979年 | 45篇 |
1978年 | 39篇 |
1977年 | 46篇 |
1976年 | 46篇 |
1975年 | 48篇 |
1974年 | 42篇 |
1973年 | 40篇 |
1972年 | 34篇 |
1971年 | 21篇 |
排序方式: 共有4086条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
During the years 1959 to 1983 a doubling in the rate of homicide took place in Copenhagen. This increase was exclusively due to an increasing number of male offenders. By comparing with another Danish material, the frequency of female homicide as well as that of homicide combined with suicide was found practically unchanged since 1946, indicating that both of these kinds of homicides seem to have a background different from those of other offences of fatal violence. During the years 1959 to 1983, the criteria of selection of the defendants for a psychiatric examination for the court were fairly consistent. Examinations were performed in practically all cases, where a charge of murder raised by the police was followed by a legal trial for homicide. Less and less of the defendants, however, were hospitalized for the examination, while more were examined in The Clinic of Forensic Psychiatry in Copenhagen. 相似文献
15.
The effects of antihypertensive therapy on left ventricular mass in elderly patients 总被引:4,自引:0,他引:4
S P Schulman J L Weiss L C Becker S O Gottlieb K M Woodruff M L Weisfeldt G Gerstenblith 《The New England journal of medicine》1990,322(19):1350-1356
Left ventricular mass sometimes decreases during treatment of hypertension, but this response is inconsistent and its effects on left ventricular function are unknown. In a six-month randomized trial, we studied the ability of verapamil and atenolol to reduce left ventricular mass in 42 elderly patients with hypertension and the effects of this reduction in mass on cardiac function. The mean blood pressure (+/- SE) decreased in both the group that received verapamil (from 171.4 +/- 3.2/93.0 +/- 2.5 mm Hg to 142.9 +/- 2.8/79.0 +/- 2.0 mm Hg) and the group that received atenolol (from 179.6 +/- 4.6/98.5 +/- 2.4 mm Hg to 148.1 +/- 3.3/83.4 +/- 1.2 mm Hg), but the atenolol-treated patients more frequently required the addition of chlorthalidone to achieve blood-pressure reduction (P less than 0.01). Verapamil resulted in a reduction in the left-ventricular-mass index from 104 +/- 5 g per square meter of body-surface area to 85 +/- 5 g per square meter (P less than 0.01). Atenolol did not produce a reduction in the left-ventricular-mass index (109 +/- 9 g per square meter before treatment vs. 112 +/- 10 g per square meter after treatment). Two weeks after the withdrawal of antihypertensive therapy, blood pressure returned to pretreatment values. Nevertheless, in patients whose left ventricular mass had decreased, two measures of diastolic filling, the peak diastolic filling rate to the peak ejection rate, were significantly higher than before treatment (2.42 +/- 0.2 vs. 3.31 +/- 0.4 [P less than 0.05] and 0.61 +/- 0.03 to 0.85 +/- 0.05 [P less than 0.05], respectively). Diastolic filling was unchanged in the group that had no reduction in left ventricular mass. Cardiac output and the ejection fraction at rest and during mild exercise were unchanged in both groups as compared with baseline values. We conclude that left ventricular mass can be reduced in elderly patients with hypertension and mild ventricular hypertrophy who receive antihypertensive therapy. Reduction occurs more frequently with verapamil than with atenolol therapy, increases diastolic filling, and does not impair systolic function. 相似文献
16.
Almeida G. L.; Hong D. A.; Corcos D.; Gottlieb G. L. 《Journal of neurophysiology》1995,74(4):1374-1381
17.
18.
The erythrocyte sedimentation rate in congestive heart failure 总被引:1,自引:0,他引:1
H L Haber J A Leavy P D Kessler M L Kukin S S Gottlieb M Packer 《The New England journal of medicine》1991,324(6):353-358
BACKGROUND AND METHODS. Physicians have long believed that the erythrocyte sedimentation rate is low in patients with congestive heart failure, but this concept is based on a misinterpretation of the results in a single report published in 1936. To reevaluate this concept in the modern era, we measured the sedimentation rate in 242 patients who were referred for treatment of chronic heart failure. RESULTS. The sedimentation rate was low (less than 5 mm per hour) in only 24 patients (10 percent) but was increased (above 25 mm per hour) in 50 percent. Patients with low or normal sedimentation rates (less than or equal to 25 mm per hour) had more severe hemodynamic abnormalities than patients with elevated rates: lower cardiac index (mean +/- SEM, 1.7 +/- 0.1 vs. 2.0 +/- 0.1 liters per minute per square meter of body-surface area) and higher mean right atrial pressure (mean +/- SEM, 12 +/- 1 vs. 9 +/- 1 mm Hg) (both P less than 0.0001). New York Heart Association functional class IV symptoms were present in 66 percent of the patients with a low or normal sedimentation rate, as compared with 42 percent of those with elevated rates (P less than 0.0001). After one to three months of therapy, patients whose sedimentation rates decreased showed little hemodynamic or clinical response to treatment, whereas both cardiac performance and functional status improved in patients whose rates increased (P less than 0.02 for the comparison between groups). The sedimentation rate was correlated with the plasma fibrinogen level (r = 0.64, P = 0.0025), and changes in the sedimentation rate during treatment were correlated inversely with changes in mean right atrial pressure (r = -0.57, P = 0.0002). During long-term follow-up, patients with low or normal sedimentation rates had a worse one-year survival than patients with elevated rates (41 vs. 66 percent, P = 0.01). CONCLUSIONS. These data indicate that the erythrocyte sedimentation rate is correlated with the severity of illness in patients with chronic heart failure. Because of its lack of discriminatory power, however, the test is of limited value in the clinical management of this disorder. 相似文献
19.
The efficacy of azidothymidine (AZT) in the treatment of patients with AIDS and AIDS-related complex. A double-blind, placebo-controlled trial 总被引:142,自引:0,他引:142
M A Fischl D D Richman M H Grieco M S Gottlieb P A Volberding O L Laskin J M Leedom J E Groopman D Mildvan R T Schooley 《The New England journal of medicine》1987,317(4):185-191
We conducted a double-blind, placebo-controlled trial of the efficacy of oral azidothymidine (AZT) in 282 patients with the acquired immunodeficiency syndrome (AIDS) manifested by Pneumocystis carinii pneumonia alone, or with advanced AIDS-related complex. The subjects were stratified according to numbers of T cells with CD4 surface markers and were randomly assigned to receive either 250 mg of AZT or placebo by mouth every four hours for a total of 24 weeks. One hundred forty-five subjects received AZT, and 137 received placebo. When the study was terminated, 27 subjects had completed 24 weeks of the study, 152 had completed 16 weeks, and the remainder had completed at least 8 weeks. Nineteen placebo recipients and 1 AZT recipient died during the study (P less than 0.001). Opportunistic infections developed in 45 subjects receiving placebo, as compared with 24 receiving AZT. The base-line Karnofsky performance score and weight increased significantly among AZT recipients (P less than 0.001). A statistically significant increase in the number of CD4 cells was noted in subjects receiving AZT (P less than 0.001). After 12 weeks, the number of CD4 cells declined to pretreatment values among AZT recipients with AIDS but not amonG AZT recipients with AIDS-related complex. Skin-test anergy was partially reversed in 29 percent of subjects receiving AZT, as compared with 9 percent of those receiving placebo (P less than 0.001). These data demonstrate that AZT administration can decrease mortality and the frequency of opportunistic infections in a selected group of subjects with AIDS or AIDS-related complex, at least over the 8 to 24 weeks of observation in this study. 相似文献
20.
K. D. Pfann D. S. Hoffman G. L. Gottlieb P. L. Strick D. M. Corcos 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,118(1):35-51
Studies of rapid, single degree-of-freedom movements have shown different changes in electromyographic patterns for movement
tasks that appear very similar (e.g., movements over different ranges of distance). However, it is not clear whether these
differences are a result of joint-specific control schemes or whether they are instead due to the limited range of task parameters
studied relative to the mechanical constraints of each joint (e.g., short compared with long movements relative to the range
of motion of a particular joint). In this study, we measured and compared the kinematic trajectories and electromyograms recorded
during various movement tasks at the wrist, elbow, and ankle. Subjects performed movements over a wide range of distances
“as fast as possible,”“at a comfortable speed,” and against two inertial loads (at the elbow only), and they performed movements
over a fixed distance at three different speeds at the wrist and ankle. For fast movements we show that, in spite of some
joint-specific differences, the basic pattern of electromyographic (EMG) modulation is similar at all three joints; for example,
the agonist EMG burst transitions from a fixed duration to an increasing duration with increasing movement distance at all
three joints. Moreover, the distance at which this transition occurs in one joint relative to the distance at which this transition
occurs in the other two joints is consistent across subjects. The transition occurs at the shortest distance at the ankle
and the longest distance at the wrist. In general we suggest that the data are consistent with a single set of control rules
applied at all three joints, with the biomechanical constraints at each joint accounting for the differences in the EMG and
kinematic patterns observed across joints.
Received: 3 September 1996 / Accepted: 10 June 1997 相似文献