全文获取类型
收费全文 | 4475篇 |
免费 | 363篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 118篇 |
儿科学 | 93篇 |
妇产科学 | 155篇 |
基础医学 | 480篇 |
口腔科学 | 71篇 |
临床医学 | 455篇 |
内科学 | 962篇 |
皮肤病学 | 53篇 |
神经病学 | 477篇 |
特种医学 | 96篇 |
外国民族医学 | 1篇 |
外科学 | 659篇 |
综合类 | 32篇 |
一般理论 | 1篇 |
预防医学 | 272篇 |
眼科学 | 202篇 |
药学 | 231篇 |
中国医学 | 7篇 |
肿瘤学 | 487篇 |
出版年
2022年 | 38篇 |
2021年 | 82篇 |
2020年 | 58篇 |
2019年 | 77篇 |
2018年 | 82篇 |
2017年 | 71篇 |
2016年 | 80篇 |
2015年 | 94篇 |
2014年 | 111篇 |
2013年 | 147篇 |
2012年 | 226篇 |
2011年 | 245篇 |
2010年 | 119篇 |
2009年 | 105篇 |
2008年 | 207篇 |
2007年 | 225篇 |
2006年 | 219篇 |
2005年 | 212篇 |
2004年 | 201篇 |
2003年 | 222篇 |
2002年 | 200篇 |
2001年 | 146篇 |
2000年 | 147篇 |
1999年 | 146篇 |
1998年 | 60篇 |
1997年 | 45篇 |
1996年 | 29篇 |
1995年 | 27篇 |
1994年 | 33篇 |
1993年 | 30篇 |
1992年 | 90篇 |
1991年 | 95篇 |
1990年 | 94篇 |
1989年 | 92篇 |
1988年 | 83篇 |
1987年 | 61篇 |
1986年 | 53篇 |
1985年 | 61篇 |
1984年 | 45篇 |
1983年 | 32篇 |
1982年 | 44篇 |
1981年 | 33篇 |
1980年 | 21篇 |
1979年 | 33篇 |
1978年 | 21篇 |
1977年 | 30篇 |
1974年 | 26篇 |
1973年 | 33篇 |
1972年 | 31篇 |
1969年 | 31篇 |
排序方式: 共有4852条查询结果,搜索用时 15 毫秒
11.
12.
Mutated recombinant human heavy-chain ferritins and myelosuppression in vitro and in vivo: a link between ferritin ferroxidase activity and biological function. 总被引:5,自引:0,他引:5 下载免费PDF全文
H E Broxmeyer S Cooper S Levi P Arosio 《Proceedings of the National Academy of Sciences of the United States of America》1991,88(3):770-774
Human heavy-chain (H-) ferritin muteins obtained by oligonucleotide site-directed mutagenesis, together with wild-type recombinant human H- and light-chain (L-) ferritins, were evaluated for in vitro effects on the suppression of human bone marrow myeloid progenitor cells and for in vivo effects on marrow and splenic myelopoiesis in C3H/HeJ mice. The 10 H-ferritin muteins exhibited alterations of various regions of the molecule, including ones exposed on the outer surface, on the inner cavity, and on the hydrophilic and hydrophobic channels and of the four-alpha-helix bundle forming the subunit structure. They were stable and were electrophoretically analogous to wild-type H-ferritin. The muteins showed in vitro and in vivo myelosuppressive activity analogous to wild type, except for mutein 222, which was totally inactive and which lacked ferroxidase activity. Recombinant human L-ferritin, devoid of ferroxidase activity, was also inactive as a suppressor. The results demonstrate that H-ferritin myelosuppressive and ferroxidase activities are linked. One possibility is that ferroxidase activity may interfere with the cellular uptake of transferrin iron that is needed for cell proliferation, an interpretation consistent with the presently described ability of hemin to overcome H-ferritin suppressive effects. 相似文献
13.
14.
Superior vena caval obstruction: a 10-year experience 总被引:3,自引:0,他引:3
One hundred and fifty-nine patients with symptoms of superior vena caval obstruction who presented to two major hospitals over a 10-year period, from 1970 to 1979, were reviewed. Lung cancer was the most common histological diagnosis. The most common symptoms were dyspnoea and a feeling of fullness in the head. The most common physical findings were dilatation of the neck or chest wall veins, or oedema of the face and arms. Superior mediastinal widening was the most common radiological abnormality. No significant morbidity was associated with any diagnostic procedure. Only patients with lymphoma had a significantly longer survival period, both from the diagnosis of the disease, and from the onset of the symptoms of superior vena caval obstruction. There is no evidence that superior vena caval obstruction is an absolute medical emergency. Appropriate diagnostic steps should be undertaken to establish the histological diagnosis. The prognosis for some tumour types may be improved by combined modality therapy (chemotherapy plus radiotherapy). 相似文献
15.
M Feinmesser L Tell H Levi 《Audiology : official organ of the International Society of Audiology》1989,28(5):268-271
A longitudinal study was performed on Jewish children with moderately-severe to profound hearing impairment born in Jerusalem during a period of 15 years (1967-1982), and the data on consanguineous matings among their parents were analyzed. These data were estimated in relation to the records obtained in an earlier survey performed on Jewish deaf children during the years 1955-1964. The rate of consanguinity among the parents of hearing-impaired children was much lower in the present survey than in the earlier one in both the Ashkenazi (Central and Eastern European origin) and the non-Ashkenazi (Asian-African origin) group. It is assumed that there is a better understanding of the genetic risk in consanguineous unions, especially when a disability such as hereditary deafness is involved. 相似文献
16.
Deep vein thrombosis and fibrinolysis. Defective urokinase type plasminogen activator release. 总被引:1,自引:0,他引:1
M Levi A W Lensing H R Büller P Prandoni G Dooijewaard S Cuppini J W ten Cate 《Thrombosis and haemostasis》1991,66(4):426-429
In the present study 57 consecutive patients with a first episode of venographically proven deep vein thrombosis were investigated to evaluate the release of tissue-type plasminogen activator (t-PA) and of urokinase-type plasminogen activator (u-PA) in response to DDAVP stimulation as well as the resting plasminogen activator inhibitor (PAI) concentration, comparing this to the results obtained in 66 similar patients with a clinical suspicion of thrombosis but with a normal venogram. All assays were performed without knowledge of the patient's status. Four patients in the deep vein thrombosis-group (7%) had an absent u-PA antigen response upon DDAVP infusion, while a normal response was observed in all control subjects. Patients and controls showed similar increases in t-PA antigen level upon DDAVP. High resting PAI antigen levels were encountered in 5 patients in the deep vein thrombosis-group (9%) and in 6 subjects in the control group (9%). The results from this controlled study indicate that a defective release of u-PA may occur in patients with deep vein thrombosis and may have pathogenetic significance. Furthermore it is concluded that elevation of PAI levels cannot be considered as a specific risk factor for venous thrombosis. 相似文献
17.
A prospective randomized trial of single-agent versus combination chemotherapy in meningeal carcinomatosis 总被引:3,自引:0,他引:3
Forty-four patients with documented meningeal carcinomatosis (small-cell lung carcinoma [SCLC], 29%; breast carcinoma, 25%) were treated in a prospective randomized trial with intrathecal methotrexate (MTX) 15 mg or MTX plus cytosine arabinoside (Ara-C) 50 mg/m2. Most patients received intrathecal hydrocortisone (HC) each treatment to minimize arachnoiditis. Overall response was 55%. Seven patients achieved complete response. Response to MTX was superior to combined MTX/Ara-C, but not significantly so (61% v 45%; P greater than .10). Response was more frequent if drugs were administered via Ommaya reservoir than by lumbar puncture (65% v 48%; P greater than .10). Concurrent radiotherapy to the CNS was associated with significantly better response (73% v 35%; P less than .05). Small-cell lung carcinoma patients showed the best response (69%). Overall median survival for the whole group was 8 weeks, but responders fared better than nonresponders (median survival, 18 v 7 weeks; P less than .05). Nausea and vomiting were the most common toxicities encountered (45%), but rarely proved limiting. An unusual, previously undocumented reaction to intrathecal HC was noted. MTX is moderately effective in nonleukemic meningeal carcinomatosis, but the addition of Ara-C does not appear to improve results. Pretreatment factors did not predict outcome in this trial. 相似文献
18.
Clival chordoma presenting with acute brain stem hemorrhage. 总被引:1,自引:0,他引:1
A D Levi W Kucharczyk A P Lang H Schutz 《The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques》1991,18(4):515-518
The authors present a case of a 29-year-old man who developed rapidly progressive cranial nerve palsies and a right hemiparesis secondary to a pontine hemorrhage. The rare but correct diagnosis of a clival chordoma which had invaded the brain stem and subsequently hemorrhaged was based on computed tomography and magnetic resonance imaging. The diagnosis was confirmed at surgery when the patient underwent a successful operative decompression of tumor and clot from the pons via a sub-occipital craniotomy. This represents the first case of a clival chordoma to hemorrhage into the brain stem, which was diagnosed preoperatively and the patient survived. 相似文献
19.
R Snyder J Bishop G Brodie W Burns A Coates J Levi D Raghavan M Schwarz M Tattersall D Thomson 《Cancer treatment reports》1987,71(3):273-276
Epirubicin was studied in a phase I setting to find the maximum tolerated dose when given weekly for 3 of 4 weeks. Forty-one evaluable patients were treated in groups at doses increasing from 20 to 45 mg/m2. The highest dose level produced the maximum degree of myelosuppression (lowest neutrophil count, 1.9 X 10(9)/L; range, 0-3.7) recorded on Day 22. This was well-tolerated in this group of mainly pretreated patients. Nonhematologic side effects were minimal. This dose schedule allows a greater dose per unit time to be administered than other recommended schedules for epirubicin. 相似文献
20.
F Levi C La Vecchia F Lucchini E Negri 《Rapport trimestriel de statistiques sanitaires mondiales》1992,45(1):117-164
A study was carried out to analyse trends in cancer mortality sex differentials. This study compared age-standardized sex ratio values for mortality from 18 cancers (or groups of cancers), and total cancer mortality over the period 1950-1989 in 24 European countries, for 4 age groups (all ages, 20-44 years, 45-64 years, and 65 years and over). For lung cancer and other tobacco-related neoplasms, appreciable rises in sex ratio values were observed until the late 1970s, particularly in Southern and Eastern Europe, before levelling off in recent years, particularly among the younger age groups. In the late 1980s, the range of variation in overall age-standardized sex ratios for lung cancer was between 2 and 3 in the United Kingdom and in Nordic countries, and around or over 10 in Southern Europe. In young adults, the decline in sex ratio values observed in Denmark and Sweden (unity), and in other Nordic countries and in the United Kingdom (around or below 2) reflects a levelling of lung cancer in young males and an increase in young females. This clearly indicates that young women are a priority target group for smoking control interventions in Europe. Appreciable cohort effects were also observed for stomach cancer: rises in sex ratio values were greater in, or restricted to, middle- and older age groups, whereas in the young there was some tendency towards a levelling in sex differentials. The overall sex ratio values for stomach cancer were around 2 in most areas of Europe in the late 1980s. For intestinal cancer, sex ratio values showed some tendency to rise, reaching a level of 1.3-1.7 in the late 1980s; steady rises were also registered in sex ratio values for melanoma (skin cancer), reaching 1.5-1.8 in the late 1980s in most countries. These upward trends which were minor or inconsistent at younger ages in several countries became progressively stronger with advancing age. Sex ratio values were below unity for cancers of the gallbladder and the thyroid. Sex ratio values tended to rise also for leukaemia (from 1.2-1.5 to 1.5-1.7), but showed no noticeable trend for lymphomas or myeloma. The overall sex ratio values for total cancer mortality in the 1950s were between 1.2 and 1.4 in most European countries. Thereafter, they rose appreciably in several countries, reaching 1.9 in Czechoslovakia, Italy and Poland, and 2.3 in France.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献