全文获取类型
收费全文 | 178060篇 |
免费 | 7144篇 |
国内免费 | 334篇 |
专业分类
耳鼻咽喉 | 3175篇 |
儿科学 | 6537篇 |
妇产科学 | 4549篇 |
基础医学 | 25244篇 |
口腔科学 | 5011篇 |
临床医学 | 13376篇 |
内科学 | 32381篇 |
皮肤病学 | 4873篇 |
神经病学 | 16303篇 |
特种医学 | 9157篇 |
外国民族医学 | 25篇 |
外科学 | 29427篇 |
综合类 | 1111篇 |
一般理论 | 42篇 |
预防医学 | 8442篇 |
眼科学 | 4779篇 |
药学 | 12375篇 |
中国医学 | 363篇 |
肿瘤学 | 8368篇 |
出版年
2023年 | 792篇 |
2021年 | 1358篇 |
2020年 | 1199篇 |
2019年 | 1417篇 |
2018年 | 3069篇 |
2017年 | 2502篇 |
2016年 | 3472篇 |
2015年 | 3814篇 |
2014年 | 4051篇 |
2013年 | 5659篇 |
2012年 | 8823篇 |
2011年 | 8200篇 |
2010年 | 4816篇 |
2009年 | 3870篇 |
2008年 | 8102篇 |
2007年 | 8925篇 |
2006年 | 8953篇 |
2005年 | 9324篇 |
2004年 | 8879篇 |
2003年 | 8733篇 |
2002年 | 8652篇 |
2001年 | 6391篇 |
2000年 | 6492篇 |
1999年 | 5612篇 |
1998年 | 1622篇 |
1997年 | 1331篇 |
1996年 | 1019篇 |
1995年 | 827篇 |
1994年 | 783篇 |
1992年 | 2481篇 |
1991年 | 2403篇 |
1990年 | 2382篇 |
1989年 | 2198篇 |
1988年 | 1938篇 |
1987年 | 1933篇 |
1986年 | 1783篇 |
1985年 | 1736篇 |
1984年 | 1339篇 |
1983年 | 1094篇 |
1979年 | 1455篇 |
1978年 | 1045篇 |
1977年 | 881篇 |
1975年 | 1105篇 |
1974年 | 1145篇 |
1973年 | 1044篇 |
1972年 | 1052篇 |
1971年 | 1020篇 |
1970年 | 917篇 |
1969年 | 859篇 |
1968年 | 826篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Dural arteriovenous malformations at the base of the anterior cranial fossa: report of nine cases 总被引:1,自引:0,他引:1
Nine men with dural arteriovenous malformations (DAVM) at the base of the anterior cranial fossa are described. Four patients had intracerebral haemorrhage and four had seizures, associated with haemorrhage in two. In three cases the fistula was an incidental finding. In five cases the diagnosis could be made before angiography, on the basis of CT findings. Angiographically, venous drainage was always seen into ascending cortical veins. Five cases demonstrated drainage via the olfactory vein into the basal vein of Rosenthal; in four this way was the principal route of drainage. Five patients underwent surgery, the therapy of choice. One fistula closed spontaneously after angiography. Two patients refused treatment and one was not treated because of his poor general condition. Because arterial supply was usually bilateral, from small branches of the ophthalmic artery, embolisation seemed to be more dangerous. Compared to dural fistulae in other locations the DAVM of the anterior cranial fossa have a higher risk of complications and should be treated even if asymptomatic at the time of diagnosis. 相似文献
102.
The results of a controlled randomized and prospective clinical study including 113 patients from March 1987 until August 1988 showed that prophylactic drainage in elective resection for cancer of the colon was not necessary. 60 patients received a drain, 53 patients were not drained. The drain turned out to be ineffective even concerning its expected function of draining intraabdominal fluid: its diagnostic and therapeutic value failed in clinical practice. The rate of surgical complications--i.e. anastomotic leakage, impaired wound healing and relaparotomy--was significantly higher in the drained group. In elective colon resection the use of a drain as a routine procedure cannot be recommended. 相似文献
103.
104.
Neuromuscular junctions (NJs) of fin muscles of teleostean fishes, Lebistes reticulatus, were ultrastructurally analyzed during 60 min of chronic exercise and a subsequent period of 90 min of induced recovery. NJs from 30-min-exercised fishes showed an almost complete depletion of synaptic vesicles (SVs), corresponding to 83% of SV consumption; 76% of axon terminals were branched at the end of this period. During the recovery period, it was possible to observe the reversibility of the changes induced by the exercise and the transitory events that lead to the reacquirement of the normal NJ morphology. After 15 min of rest, SV population increased to a value of 54.6 SVs/micron2 and the percentage of branched axons was 66.5%. At 60 min of recovery the number of SVs reached a value of 84.6 SVs/micron2. The SV population was fully reestablished at 80 min of rest, while the percentage of branched axons was found within normal ranges after 90 min of recovery. These results demonstrate that chronic exercise induced physiological depletion of NJ SVs and other axon terminal morphological changes, as well as that postexercise rest induces the reestablishment of the normal NJ morphology. 相似文献
105.
D. Lothschütz M. Jennewein S. Pahl H.F. Lausberg A. Eichler W. Mutschler R.G. Hanselmann M. Oberringer 《Inflammation research》2002,51(8):416-422
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi. 相似文献
106.
107.
The experimental infection of immunocompetent and immunodeficient athymic mice with an avirulent encephalitogenic Toxoplasma strain (DX strain) was employed to study the ensuing encephalitic process by use of histological and immunocytochemical methods. In the acute phase of the infection Toxoplasma cysts and tachyzoites were accompanied by an infiltrate composed of macrophages, CD4+ and CD8+ T cells. In the chronic stage a granulomatous encephalitis developed. In contrast to immunocompetent NMRI mice, athymic nude NMRI mice died 3 weeks post-infection because of a generalized toxoplasmosis with predominant involvement of the brain. A salient feature of murine Toxoplasma encephalitis was up-regulation of class I and II major histocompatibility complex (MHC) gene products. Class I antigen was widely expressed on microglial cells and astrocytes. Class II antigen was only expressed on microglial cells despite a considerable astrogliosis. Our results indicate a differential expression of MHC-determined antigens on brain cells in acute and chronic murine Toxoplasma encephalitis. 相似文献
108.
109.
Synthesis of Estradiol Haptens Two estradiol haptens, 4-(3β,17β-dihydroxyestran-7α-yl)butanoic acid ( 9 ) and 7α-(4-aminobutyl)-3β,17β-estradiols ( 13 ), were prepared from 19-nortestosterone by partial synthesis. The binding activity for the cytosol estrogen receptor was determined by competition against [3H]-estradiol; at a concentration of 2×10?7mol/l, compound 9 displaces 50% of [3H]-estradiol. Attached to AH-Sepharose 4B compound 9 allows the cytosol estrogen receptor from calf uterus to be concentrated 1800-fold by affinity chromatography. 相似文献
110.
M Havel H Teufelsbauer P Kn?bl R Dalmatiner P Jaksch W Zw?lfer M Müller T Vukovich 《The Journal of thoracic and cardiovascular surgery》1991,101(6):968-972
To study the hemostyptic effect of aprotinin (Trasylol) in patients undergoing extracorporeal circulation for coronary artery bypass operations, we randomized 12 of 24 patients to receive aprotinin in high dosage (about 800 mg) during extracorporeal circulation. From the resulting two groups each, one patient was excluded from the study because of postoperative myocardial infarction (control group) and surgical hemorrhage (aprotinin group) leading to a second operation. Although heparin was used for anticoagulation in all 22 patients, all had a marked increase in plasma levels of thrombin-antithrombin III complexes during extracorporeal circulation, indicating an intravasal activation of coagulation. By monitoring the plasma levels of fibrin degradation products in patients without aprotinin therapy, we recorded a concomitant hyperfibrinolysis significantly less pronounced in patients receiving aprotinin (p less than 0.005). The mean total postoperative blood loss was lower in patients receiving aprotinin (620 ml) than in control patients (1000 ml; p less than 0.03). The results confirm previous reports of a hemostyptic effect of aprotinin in cardiac operations. This effect is probably due to a prevention of hyperfibrinolysis. 相似文献