全文获取类型
收费全文 | 18081篇 |
免费 | 1416篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 338篇 |
儿科学 | 381篇 |
妇产科学 | 256篇 |
基础医学 | 2347篇 |
口腔科学 | 539篇 |
临床医学 | 1722篇 |
内科学 | 3571篇 |
皮肤病学 | 238篇 |
神经病学 | 1882篇 |
特种医学 | 608篇 |
外科学 | 2517篇 |
综合类 | 276篇 |
一般理论 | 16篇 |
预防医学 | 1750篇 |
眼科学 | 408篇 |
药学 | 1206篇 |
1篇 | |
中国医学 | 10篇 |
肿瘤学 | 1469篇 |
出版年
2023年 | 92篇 |
2022年 | 166篇 |
2021年 | 304篇 |
2020年 | 216篇 |
2019年 | 258篇 |
2018年 | 331篇 |
2017年 | 254篇 |
2016年 | 264篇 |
2015年 | 285篇 |
2014年 | 445篇 |
2013年 | 783篇 |
2012年 | 1012篇 |
2011年 | 1070篇 |
2010年 | 636篇 |
2009年 | 611篇 |
2008年 | 1072篇 |
2007年 | 1154篇 |
2006年 | 1167篇 |
2005年 | 1129篇 |
2004年 | 1107篇 |
2003年 | 1140篇 |
2002年 | 1090篇 |
2001年 | 222篇 |
2000年 | 137篇 |
1999年 | 196篇 |
1998年 | 243篇 |
1997年 | 231篇 |
1996年 | 224篇 |
1995年 | 188篇 |
1994年 | 157篇 |
1993年 | 129篇 |
1992年 | 155篇 |
1991年 | 139篇 |
1990年 | 135篇 |
1989年 | 109篇 |
1988年 | 118篇 |
1987年 | 108篇 |
1986年 | 111篇 |
1985年 | 113篇 |
1984年 | 150篇 |
1983年 | 164篇 |
1982年 | 186篇 |
1981年 | 159篇 |
1980年 | 183篇 |
1979年 | 90篇 |
1978年 | 130篇 |
1977年 | 103篇 |
1976年 | 115篇 |
1974年 | 94篇 |
1973年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Routine ultrasound may have a positive effect on obstetric outcome when determination of gestational age and placental localization are combined with evaluation for multiple gestation, congenital anomalies and growth retardation. The potential risk and benefit of obstetric ultrasound must be better understood before this procedure is used as a screening tool in large populations. 相似文献
32.
33.
Vernon P Holt 《Primary dental care》2007,14(4):149-153
The drive for quality assurance in general dental practice has arisen as a response to changing standards and demands. Dentists need to develop skills in change management in this new culture of change. Groups of practitioners often encounter difficulties when managing change, yet it is essential that they lead the process. Such problems are common among groups of professionals. A wide range of topics is presented that may, from one point of view, represent challenging or problem areas (obstacles) for a group practice but may also, from a different point of view, provide a framework of opportunities for improvement, and facilitate the management processes within the practice and the management of change in particular (tools). The range of skills required to assist a professional group is such that individual dentists or advisers may not be able to achieve much on their own. The best way forward may be to interpret the problems as a professional training need and to organise training as a group. These issues will be considered under the following headings: partners and teams; introduction: the need for change management; the challenge for group practices; obstacles and tools; conclusion: the way forward--a case for training. 相似文献
34.
Jack Yu-Shih Lin Shun-Ling Lin Wei-Lin Chen Ying-Shan Chen 《Ophthalmic surgery, lasers & imaging》2005,36(2):158-162
A 29-year-old man who had been treated for acute anterior uveitis in a local medical office and observed for 1 month presented complaining of distorted vision in his left eye for 1 week. On ophthalmic examination, the anterior segment was relatively quiet with few cells. A posterior segment examination revealed cystoid macular edema and multiple splinter retinal hemorrhages. Results of all laboratory and imaging studies were negative, except for a positive HLA-B27 haplotype. Fluorescein angiography revealed massive leakage in the mid and late phase, consistent with chorioretinitis. Periocular corticosteroid injections and oral prednisolone were administered. The patient responded to the treatment well with subsequent resolution of chorioretinitis 2 months later. Although rare, chorioretinitis can occur in the setting of uveitis associated with HLA-B27 and seems to respond well to corticosteroid treatment. 相似文献
35.
Functional MRI in Epilepsy 总被引:2,自引:2,他引:0
36.
A bstract Isolated mitral valve replacement using the CarboMedics prosthetic mitral valve (CarboMedics, Inc., Austin, TX) was studied in 13 centers in the United States, Canada, and Scandinavia between 1987 and 1993 in 428 patients with a mean age of 57 ± 14 years. Actuarial survivals at 1, 2, and 5 years were 88.2% and 75.8%. Freedom from events at 5 years were 94.8% for major thromboembolism, 96.6% for thrombosis, and 96.7% for endocarditis. Linearized morbidity rates (events per 100 patient years) for events at > 30 days postoperatively were .51 thrombosis, 1.1 major thromboembolism, and .37 endocarditis. These results at early to mid-term compare favorably with the first generation bileaflet valve. 相似文献
37.
Jack Yamuy John K. Engelhardt Francisco R. Morales Michael H. Chase 《Brain research》1992,570(1-2):300-306
The objective of this study was to determine whether the aging process influences the changes in the electrophysiological properties of motoneurons that occur as a consequence of axotomy. Accordingly, using intracellular recording and stimulating techniques, the basic electrical properties of control (unaxotomized) and axotomized spinal cord motoneurons of aged cats were determined. Compared with control motoneurons, axotomized motoneurons exhibited increases in input resistance (Rin), membrane time constant (τb) and the equalizing time constant (τc). While the electrotonic length (L) remained unchanged, axotomy induced a decrease in the total cell capacitance (Ccell. The post-axotomy reduction of Ccell indicates that the motoneuron surface area was reduced and the increased membrane time constant indicates that there was an increase in membrane resistivity (Rm). The post-axotomy conservation of L accompanied by an increase in Rm suggests that aged axotomized motoneurons undergo geometrical changes. Furthermore, calculations based on cable theory suggest that the diameter of the equivalent cylinder (d) decreased following axotomy, whereas the equivalent cylinder length (l) remained unaffected. It is concluded that axotomy produces significant alterations in the soma-dendritic portion of aged spinal motoneurons, as indicated by the changes found in their passive electrophysiological properties, and that the pattern of the response that occurs in axotomized motoneurons of adult cats is also present in axotomized motoneurons of aged animals. 相似文献
38.
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
39.
40.
Laparoscopic Cholecystectomy for Acute Cholecystitis: Prospective Trial 总被引:23,自引:0,他引:23
Samuel Eldar Edmond Sabo Ernest Nash Jack Abrahamson Ibrahim Matter 《World journal of surgery》1997,21(5):540-545
p
< 0.00001) and for hydrops (28.5%) and empyema of the gallbladder
(28.5%) (
p
= 0.004). The difference in conversion
between the group with acute necrotizing (gangrenous) cholecystitis and
the two groups with hydrops and empyema of the gallbladder was not
statistically significant (
p
= 0.07). The complication
rates of acute cholecystitis, hydrops, empyema of the gallbladder, and
gangrenous cholecystitis were 9.0%, 9.5%, 14.0%, and 20.0%,
respectively (
p
= NS). Patients with an operative
delay of 96 hours or less from the onset of acute cholecystitis had a
conversion rate of 23%, whereas a delay of more than 96 hours was
associated with a conversion rate of 47% (
p
= 0.022).
The complication rate was 8.5% in the laparoscopic group and 27% in
the converted group (
p
= 0.013). Patients over 65
years of age, with a history of biliary disease, a nonpalpable
gallbladder, WBC count over 13,000/cc, and acute gangrenous
cholecystitis were independently associated with a high LC conversion
rate; male patients, finding large bile stones, serum bilirubin over
0.8 mg/dl, and WBC count over 13,000/cc were independently associated
with a high complication rate following laparoscopic surgery with or
without conversion. Generally, LC can be performed safely for acute
cholecystitis, with acceptably low conversion and complication rates.
Different forms of cholecystitis carry various conversion and
complication rates in selected cases. LC for acute cholecystitis should
be performed within 96 hours of the onset of disease. Predictors of
conversion and complications may be helpful when planning the
laparoscopic approach to acute cholecystitis. 相似文献