全文获取类型
收费全文 | 19374篇 |
免费 | 1930篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 273篇 |
儿科学 | 532篇 |
妇产科学 | 350篇 |
基础医学 | 2914篇 |
口腔科学 | 382篇 |
临床医学 | 2320篇 |
内科学 | 3607篇 |
皮肤病学 | 363篇 |
神经病学 | 1580篇 |
特种医学 | 663篇 |
外科学 | 2878篇 |
综合类 | 398篇 |
一般理论 | 29篇 |
预防医学 | 2091篇 |
眼科学 | 235篇 |
药学 | 1598篇 |
中国医学 | 35篇 |
肿瘤学 | 1102篇 |
出版年
2023年 | 120篇 |
2022年 | 207篇 |
2021年 | 440篇 |
2020年 | 221篇 |
2019年 | 396篇 |
2018年 | 423篇 |
2017年 | 334篇 |
2016年 | 369篇 |
2015年 | 419篇 |
2014年 | 564篇 |
2013年 | 776篇 |
2012年 | 1094篇 |
2011年 | 1093篇 |
2010年 | 633篇 |
2009年 | 590篇 |
2008年 | 991篇 |
2007年 | 980篇 |
2006年 | 1014篇 |
2005年 | 921篇 |
2004年 | 868篇 |
2003年 | 788篇 |
2002年 | 721篇 |
2001年 | 454篇 |
2000年 | 468篇 |
1999年 | 390篇 |
1998年 | 200篇 |
1997年 | 169篇 |
1996年 | 162篇 |
1995年 | 144篇 |
1994年 | 134篇 |
1993年 | 145篇 |
1992年 | 298篇 |
1991年 | 301篇 |
1990年 | 298篇 |
1989年 | 299篇 |
1988年 | 271篇 |
1987年 | 243篇 |
1986年 | 218篇 |
1985年 | 230篇 |
1984年 | 221篇 |
1983年 | 175篇 |
1982年 | 136篇 |
1981年 | 138篇 |
1980年 | 119篇 |
1979年 | 186篇 |
1978年 | 178篇 |
1977年 | 136篇 |
1976年 | 121篇 |
1974年 | 155篇 |
1973年 | 146篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Despite growing concern with rural elderly populations, little attention has focused on their mental health, ways it may correlate with physical health, or how rural mental health patterns compare to urban. Popular wisdom contends that elderly people in general, and rural elderly persons in particular, are at increased risk for mental illness. This article examines these questions. A review of available literature suggests that elderly people may be at only slightly greater risk of mental illness than the population at large, though there are some indications that rates of depression may be somewhat higher among the elderly population. Much of this same literature implies that objective environmental conditions play a significant role in the incidence of depression. Analysis of data gathered in a statewide random poll (N = 743) indicates that while physical health tends to be poorer among rural populations, when health is held constant there is actually an inverse relationship between age and depression. Therefore, rural elderly persons are no more likely to be depressed than their urban counterparts despite harsher living conditions. Both conceptual and policy implications are discussed. 相似文献
13.
Mice killed shortly after receiving c. 2000 spores of a type E strain of Clostridium botulinum per os were incubated at one of five chosen temperatures together with bottles of cooked meat medium seeded with a similar inoculum. After incubation the rotting carcasses were homogenized. Sterile membrane filtrates of the homogenates (10%, w/v) and pure cultures were then titrated for toxicity. Some of the main findings were confirmed with two further type E strains. Toxicity produced at 37 degrees C was poor in both carcasses and cultures (200-20,000 mouse intraperitoneal LD/g or ml). It was good in both systems at 30 and 23 degrees C, usually reaching 20,000-200,000 LD/g or ml, and in carcasses occasionally more; at 30 degrees C maximal toxicity was reached more quickly in carcasses than in cultures. Prolonged incubation (36-118 days) at 30 or 23 degrees C resulted in complete loss of toxicity in virtually all carcasses but not in cultures. At 16 degrees C the development of toxicity in carcasses was strikingly greater than in cultures. At 9 degrees C neither system produced more than slight toxicity after prolonged incubation. Trypsinization increased the toxicity of cultures but not usually of carcasses. Unfiltered carcass homogenate (10%, w/v) with maximal intraperitoneal toxicity was harmless for mice by mouth in doses of 0.25 ml. These findings differed in important respects from those made earlier with a type C strain. 相似文献
14.
15.
We present a noninvasive, in vivo model for strain application in the tibiae of rats. The hind limb of each animal was placed into a device that applied four point bending to the tibia. Bending was applied in the medial-lateral direction causing compression on the lateral surface of the tibia and tension on the anteromedial surface. The peak strain magnitudes were estimated to be between 1600 and 3500 mu strain. In this pilot work, data were collected from 12 rats. The rats received either one cycle per day, four cycles per day, 12 cycles per day, 36 cycles per day, or 108 cycles per day of bending. The experimental (right) tibiae from all of the rats showed new bone formation after 12 days. The control (left) tibiae showed no new bone formation over this period. A better organized, dense bony reaction occurred in regions of lesser strains than in regions of higher strains, where there was a large accumulation of bone easily identified as woven. The organization and density of the newly formed bone appeared to be inversely related to the peak strains in the region. After 40 days of daily loading, the new bone area appeared to be more compact and better mineralized. However, bone formation was still occurring after 40 days. The results of this study suggest that woven bone formation occurred due to the bending stimulus and not due to pathology. 相似文献
16.
Lithium is a widely prescribed drug used for the treatment of bipolar affective illness. Previous reports on its effects on sperm motility and male fertility are conflicting. The effect of lithium on human sperm motility was examined in vitro using the modified transmembrane migration method. This technique takes account of the dilution of lithium that occurs during the incubation. Lithium inhibits human sperm motility in vitro in concentrations comparable with those reported to be achieved in semen after oral administration. 相似文献
17.
Ann G Schwartz Geoffrey M Prysak Valerie Murphy Fulvio Lonardo Harvey Pass Jan Schwartz Sam Brooks 《Clinical cancer research》2005,11(20):7280-7287
PURPOSE: A role for estrogens in determining lung cancer risk and prognosis is suggested by reported sex differences in susceptibility and survival. Archival lung tissue was evaluated for the presence of nuclear estrogen receptor (ER)-alpha and ER-beta and the relationship between ER status, subject characteristics, and survival. EXPERIMENTAL DESIGN: Paraffin-embedded lung tumor samples were obtained from 214 women and 64 men from two population-based, case-control studies as were 10 normal lung autopsy samples from patients without cancer. Nuclear ER-alpha and ER-beta expression was determined by immunohistochemistry. Logistic regression was used to identify factors associated with ER positivity and Cox proportional hazards models were used to measure survival differences by ER status. RESULTS: Neither tumor (0 of 94) nor normal (0 of 10) lung tissue stained positive for ER-alpha. Nuclear ER-beta positivity was present in 61% of tumor tissue samples (170 of 278; 70.3% in men and 58.3% in women) and 20% of normal tissue samples (2 of 10; P = 0.01). In multivariate analyses, females were 46% less likely to have ER-beta-positive tumors than males (odds ratio, 0.54; 95% confidence interval, 0.27-1.08). This relationship was stronger and statistically significant in adenocarcinomas (odds ratio, 0.40; 95% confidence interval, 0.18-0.89). Women with ER-beta-positive tumors had a nonsignificant 73% (P = 0.1) increase in mortality, whereas men with ER-beta-positive tumors had a significant 55% (P = 0.04) reduction in mortality compared with those with ER-beta-negative tumors. CONCLUSIONS: This study suggests differential expression by sex and influence on survival in men of nuclear ER-beta in lung cancer, particularly in adenocarcinomas. 相似文献
18.
19.
20.
B G Turner J R Saltzman L Hua R Maurer Natan Feldman D L Carr-Locke R Burakoff J J Liu 《Journal canadien de gastroenterologie》2007,21(11):737-741
BACKGROUND: Wireless pH studies can offer prolonged pH monitoring, which may potentially facilitate the diagnosis and management of patients with gastroesophageal reflux disease (GERD). The aim of the present study was to evaluate the detection rate of abnormal esophageal acid exposure using prolonged pH monitoring in patients with suspected or refractory GERD symptoms. METHODS: Patients undergoing prolonged ambulatory pH studies for the evaluation of GERD-related symptoms were assessed. Patients with a known diagnosis of GERD were tested on medical therapy, while patients with suspected GERD were tested off therapy. The wireless pH capsules were placed during upper endoscopy 6 cm above the squamocolumnar junction. RESULTS: One hundred ninety-one patients underwent a total of 198 pH studies. Fifty ambulatory pH studies (25%) were excluded from the analysis: 27 patients (14%) had insufficient data capture (less than 18 h on at least one day of monitoring), 15 patients had premature capsule release (7%), seven were repeat studies (3.5%) and one had intolerable pain requiring capsule removal (0.5%). There were 115 patients undergoing pH studies who were off medication, and 33 patients were on therapy. For the two groups of patients, results were as follows: 32 (28%) and 22 (67%) patients with normal studies on both days; 58 (50%) and five (15%) patients with abnormal studies on both days; 18 (16%) and three (9%) patients with abnormal studies on day 1 only; and seven (6%) and three (9%) patients with abnormal studies on day 2 only, respectively. CONCLUSIONS: Prolonged 48 h pH monitoring can detect more abnormal esophageal acid exposure but is associated with a significant rate of incomplete studies. 相似文献