全文获取类型
收费全文 | 12698篇 |
免费 | 1173篇 |
国内免费 | 155篇 |
专业分类
耳鼻咽喉 | 557篇 |
儿科学 | 265篇 |
妇产科学 | 95篇 |
基础医学 | 1235篇 |
口腔科学 | 204篇 |
临床医学 | 666篇 |
内科学 | 943篇 |
皮肤病学 | 314篇 |
神经病学 | 728篇 |
特种医学 | 823篇 |
外科学 | 564篇 |
综合类 | 683篇 |
现状与发展 | 1篇 |
预防医学 | 4635篇 |
眼科学 | 186篇 |
药学 | 1685篇 |
2篇 | |
中国医学 | 38篇 |
肿瘤学 | 402篇 |
出版年
2024年 | 21篇 |
2023年 | 182篇 |
2022年 | 388篇 |
2021年 | 485篇 |
2020年 | 473篇 |
2019年 | 455篇 |
2018年 | 435篇 |
2017年 | 559篇 |
2016年 | 514篇 |
2015年 | 476篇 |
2014年 | 716篇 |
2013年 | 1185篇 |
2012年 | 632篇 |
2011年 | 718篇 |
2010年 | 526篇 |
2009年 | 554篇 |
2008年 | 577篇 |
2007年 | 534篇 |
2006年 | 488篇 |
2005年 | 451篇 |
2004年 | 368篇 |
2003年 | 317篇 |
2002年 | 260篇 |
2001年 | 250篇 |
2000年 | 251篇 |
1999年 | 163篇 |
1998年 | 184篇 |
1997年 | 158篇 |
1996年 | 181篇 |
1995年 | 160篇 |
1994年 | 135篇 |
1993年 | 119篇 |
1992年 | 150篇 |
1991年 | 124篇 |
1990年 | 121篇 |
1989年 | 90篇 |
1988年 | 78篇 |
1987年 | 69篇 |
1986年 | 42篇 |
1985年 | 82篇 |
1984年 | 76篇 |
1983年 | 52篇 |
1982年 | 52篇 |
1981年 | 41篇 |
1980年 | 30篇 |
1979年 | 27篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 17篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Bente E. Moen Bjrg E. Hollund Morten Berntsen Ragnar Flo Knut Rasmus Kyvik Trond Riise 《American journal of industrial medicine》1995,27(4):555-564
Occupational exposure to carcinogenic agents on the decks on six Norwegian crude oil tankers was examined in five harbors. The purpose of the study was to evaluate the need for improving the working environment on deck on these tankers. Technical arrangments and the work itself on the deck were observed during loading or unloading. Occupational monitoring was performed by active sampling of benzene, polyaromatic hydrocarbons, and some aldehydes. The crew answered a questionnaire concerning their work, use of protective equipment, and occurrence of acute symptoms. The levels of air-borne carcinogenic agents were low, probably due to closed loading systems on all tankers. However, the seamen reported discomfort during the work that may be related to other chemical agents in the cargo. The seamen were frequently painting with lead chromate paint without using personal protective equipment. This type of chemical exposure should be evaluated. 相似文献
54.
In a group of 43 smelter workers exposed to inorganic arsenic dust for 13-45 years, nerve conduction velocities (NCVs) were significantly lower in two peripheral nerves as compared with matching referents. With multivariate data analysis, a significant negative correlation was found between cumulative absorption of arsenic and NCV in four examined nerves and the sural amplitude. Clinical symptoms of neuropathy and other symptoms related to arsenic exposure were moderate, though the difference between the groups was significant. The mean total absorption of arsenic was calculated to be less than 5 g, and the maximal absorption about 20 g. These data indicate that the adverse effect of arsenic on the peripheral nerves is dependent on long-term exposure rather than on short-term fluctuations in exposure levels. © 1994 Wiley-Liss, Inc. 相似文献
55.
Frank de Vocht Berna van-Wendel-de-Joode Hans Engels Hans Kromhout 《Magnetic resonance in medicine》2003,50(4):670-674
The interactive use of magnetic resonance imaging (MRI) techniques is increasing in operating theaters. A study was performed on 17 male company volunteers to assess the neurobehavioral effects of exposure to magnetic fields from a 1.5 Tesla MRI system. The subjects' neurobehavioral performances on a neurobehavioral test battery were compared in four 1-hr sessions with and without exposure to magnetic fields, and with and without additional movements. Adverse effects were found for hand coordination (-4%, P < 0.05; Pursuit Aiming II) and near visual contrast sensitivity (-16% and -15%, P < 0.10; Vistech 6000). The results from the remaining tests were inconclusive due to a strong learning effect. No additional effect from gradient fields was detected. The results indicate that working near a 1.5 Tesla MRI system may lead to neurobehavioral effects. Further research is recommended, especially in members of operating teams using interactive MRI systems. 相似文献
56.
This retrospective analysis reviews the clinical experience of a major urban referral hospital with diffuse malignant pleural mesothelioma during the 14-year period from 1973 through 1986. Seventy-five cases of definite or equivocal mesothelioma were identified. There were four cases of primary malignant peritoneal mesothelioma, seven cases of benign fibrous mesothelioma, and 64 cases of diffuse malignant pleural mesothelioma. In 43 cases (67%) of diffuse malignant pleural mesothelioma, there was historic evidence of asbestos exposure. In 21 cases (33%), there was no known history of asbestos exposure. An increase in annual incidence of diffuse malignant pleural mesothelioma was observed over the study period, from three cases in 1973 to ten cases in 1986. Despite greater awareness of this disease, the diagnosis remains a difficult one to establish given the nonspecific symptoms, signs and radiographic appearance, variable histologic appearance, and poor diagnostic sensitivity and specificity of thoracentesis and closed pleural biopsy. Thoracotomy, thoracoscopy, and CT-guided needle biopsies gave higher yields and are the diagnostic measures of choice when diffuse malignant pleural mesothelioma is suspected. 相似文献
57.
A new technique for multistep phase-contrast image processing is presented. The N-step method consists of simply forming the linear average of the N — 1 adjacent phase-difference signals. It has similar noise reduction properties as other multistep techniques, but the simplicity of the noise variance of the N-step technique allows intuitive insight into phase-difference phase-contrast processing and noise reduction, which can aid in the design of efficient and improved phase-contrast imaging sequences. As well, the computational simplicity of the N-step phase-difference technique compared with any other known multistep technique is advantageous. Like other multistep techniques, it has far more efficient noise reduction properties than simple two-step, multiple average phase-contrast imaging, even when normalized for total scan time. A three-step phase-difference velocity image has 50% less variance than an image acquired with two steps and two scans averaged but is obtained in 25% less scan time. Given its advantages, it should now be the chosen technique for increasing velocity-to-noise and contrast-to-noise ratios in all phase-difference phase-contrast clinical applications. 相似文献
58.
A. C. Metting van Rijn A. Peper C. A. Grimbergen 《Medical & biological engineering & computing》1991,29(4):433-440
A multichannel instrumentation amplifier, developed to be used in a miniature universal eight-channel amplifier module, is
described. After discussing the specific properties of a bioelectric recording, the difficulties of meeting the demanded specifications
with a design based on operational amplifiers are reviewed. Because it proved impossible to achieve the demanded combination
of low noise and low power consumption using commercially available operational amplifiers, an amplifier equipped with an
input stage with discrete transistors was developed. A new design concept was used to expand the design to a multichannel
version with an equivalent input noise voltage of 0·35 μV RMS in a bandwidth of 0·1–100 Hz and a power consumption of 0·6
mW per channel. The results of this study are applied to miniature, universal, eight-channel amplifier modules, manufactured
with thick-film production techniques. The modules can be coupled to satisfy the demand for a multiple of eight channels.
The low power consumption enables the modules to be used in all kinds of portable and telemetry measurement systems and simplifies
the power supply in stationary measurement systems. 相似文献
59.
Louise Nadon Jack Siemiatycki Ron Dewar Daniel Krewski Michel Grin 《American journal of industrial medicine》1995,28(3):303-324
Polycyclic aromatic hydrocarbons (PAHs) demonstrate carcinogenic activity in animal models. Although some epidemiologic studies have implicated PAHs as risk factors for human cancer, the evidence reported to date has not been consistent. The purpose of this report is to describe the associations between occupational exposure to PAHs in the workplace and each of 14 types of cancer. A population-based, case-control study was carried out in Montreal to investigate associations between a large variety of environmental and occupational exposures on the one hand, and several types of cancer on the other. A detailed job history was obtained from each subject along with information on a number of potential confounders. Each job history was reviewed by a team of experts, who used this information to construct a corresponding history of occupational exposures. Among the PAH exposures considered were benzo(a)pyrene (B(a)P) and five categories of PAHs defined on the basis of the source material, namely, wood, petroleum, coal, other sources, and any source. Altogether, 3,730 cancer patients and 533 population controls were interviewed and their job exposure histories coded. For each of 14 types of cancer analyzed, three control groups were available: other cancer patients, population controls, and the pooled set of cancer and population controls. The associations between 14 cancer types and 6 PAH exposures were analyzed using logistic regression methods. For most types of cancer evaluated, there was no evidence of excess risk due to PAHs at the levels encountered in the occupations in which PAH exposure has been prevalent in the Montreal area. For a few cancer sites–the esophagus, the pancreas, and the prostate gland–there were suggestions of excess risk; these observations are noteworthy hypotheses for further investigation. For lung cancer, there appeared to be an increased risk due to PAHs among nonsmokers and light smokers, but not among heavy smokers. 相似文献
60.
接触汞对男工生殖功能影响的调查研究 总被引:1,自引:0,他引:1
本文选择接触汞男工117名,对照组123名对他们的性功能、男工妻子妊娠的结局、胎儿发育和子代生长状况进行了回顾性调查。接触汞男工的阳萎、早泄和性减退率明显增高,每周的性交次数明显减少,与对照组比较均有显著性差异(P<0.05),男工妻子的早产、自然流产、难产和围产儿死亡率高于对照组。本文调查结果说明无机汞可能引起男性功能障碍。 相似文献