全文获取类型
收费全文 | 16609篇 |
免费 | 993篇 |
国内免费 | 291篇 |
专业分类
耳鼻咽喉 | 256篇 |
儿科学 | 241篇 |
妇产科学 | 61篇 |
基础医学 | 1368篇 |
口腔科学 | 117篇 |
临床医学 | 1516篇 |
内科学 | 2470篇 |
皮肤病学 | 81篇 |
神经病学 | 3803篇 |
特种医学 | 481篇 |
外科学 | 1776篇 |
综合类 | 1780篇 |
预防医学 | 503篇 |
眼科学 | 1001篇 |
药学 | 1027篇 |
6篇 | |
中国医学 | 875篇 |
肿瘤学 | 531篇 |
出版年
2024年 | 54篇 |
2023年 | 256篇 |
2022年 | 437篇 |
2021年 | 590篇 |
2020年 | 555篇 |
2019年 | 489篇 |
2018年 | 505篇 |
2017年 | 551篇 |
2016年 | 504篇 |
2015年 | 493篇 |
2014年 | 965篇 |
2013年 | 1221篇 |
2012年 | 898篇 |
2011年 | 1003篇 |
2010年 | 709篇 |
2009年 | 783篇 |
2008年 | 742篇 |
2007年 | 750篇 |
2006年 | 669篇 |
2005年 | 571篇 |
2004年 | 547篇 |
2003年 | 462篇 |
2002年 | 379篇 |
2001年 | 359篇 |
2000年 | 276篇 |
1999年 | 247篇 |
1998年 | 232篇 |
1997年 | 280篇 |
1996年 | 249篇 |
1995年 | 192篇 |
1994年 | 184篇 |
1993年 | 187篇 |
1992年 | 192篇 |
1991年 | 126篇 |
1990年 | 127篇 |
1989年 | 116篇 |
1988年 | 91篇 |
1987年 | 99篇 |
1986年 | 112篇 |
1985年 | 109篇 |
1984年 | 104篇 |
1983年 | 36篇 |
1982年 | 71篇 |
1981年 | 65篇 |
1980年 | 52篇 |
1979年 | 46篇 |
1978年 | 35篇 |
1977年 | 31篇 |
1976年 | 24篇 |
1973年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Francisco J. Romero Juan Segura-Aguilar Elena Monsalve Carlos Hermenegildo Eberhard Nies Francisco J. Puertas Joaquí n Rom 《Neurotoxicology and teratology》1990,12(6):603-605
The present work tries to establish the antioxidant capacity of the peripheral nervous tissue of the rat, in terms of the enzymatic activities present in this tissue that either prevent the formation of activated species as the semiquinone radical (DT-diaphorase), protect against activated oxygen species (superoxide dismutase, glutathione peroxidase), conjugate natural toxic products or xenobiotics (glutathione S-transferases, especially the activity conjugating 4-hydroxy-nonenal), or complete the glutathione system metabolism (glutathione disulfide reductase, γ-glutamyl transpeptidase). All the activities studied are lower in this tissue than they are in liver, except for γ-glutamyl transpeptidase. The relevance of the results obtained and its possible relationship with different neuropathies is discussed. It is concluded that the peripheral nervous tissue is by far less protected than the liver against oxidative damage. 相似文献
32.
Emmanuel Ellie Anne Vital Andreas Steck Jean-Michel Boiron Claude Vital Jean Julien 《Journal of neurology》1996,243(1):34-43
We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46–81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG. 相似文献
33.
将大鼠的腓总神经切断后,进行如下4组实验:A.原位3mm间隙动脉套桥接,B.原位断端外膜缝合,C远侧断端旋转180°3mm间隙动脉套桥接,D远侧端旋转180°外膜缝合。术后12周的电生理学,组织学评价显示,B组神经再生效果最佳,A、C两组接近B组,而D组较差。 相似文献
34.
G. Van Goethem J.-J. Martin A. Lfgren I. Dehaene P. Tack M. Van Zandycke D. Ververken C. Ceuterick C. Van Broeckhoven 《European journal of neurology》1997,4(5):476-484
We studied 14 patients from three unrelated Belgian pedigrees with a familial mitochondrial disorder and multiple deletions of mitochondrial DNA (mtDNA). In one family with an oculopharyngeal presentation there is a clear autosomal dominant inheritance. Progressive external ophthalmoplegia (PEO), “ragged red fibres” (RRF) and multiple deletions of mtDNA are common to all three families. Therefore a diagnosis of autosomal dominant progressive ophthalmoplegia with multiple deletions of mtDNA (adPEO) was made in one family at least. Our data confirm the previous observations that adPEO is a systemic disorder rather than a pure myopathy. In our pedigrees frequently associated features include axonal peripheral neuropathy, dysphagia, psychiatric illness, and sudden death. Mild ataxia, pes cavus and mitral valve prolapse with associated mitral insufficiency also occur. In some cases onset is atypical with neuropathy, adolescent onset myopathy or psychiatric illness. In such cases the common features of PEO and muscle weakness always complete the clinical phenotype later during the course of the disease. Biochemical studies on mitochondrial fractions prepared from one patient's muscle, revealed no abnormalities of respiratory chain enzyme activities. 相似文献
35.
36.
37.
Rolf Gronas B. Eng Peter G. Kalman MD Daryl S. Kucey MD Graham A. Wright PhD 《Journal of magnetic resonance imaging : JMRI》1997,7(4):637-643
Flow-independent angiography (FIA), an approach that isolates arterial blood using MR relaxation characteristics rather than flow effects, was evaluated for application in peripheral vascular disease (PVD). First, pilot studies were conducted in which FIA coronal projection images were obtained from controls and symptomatic patients with PVD to assess clinical utility. All control images corresponded to the expected leg arterial anatomy with little interference from deep veins (one of five) and muscle (zero of five). Superficial venous signal was less well suppressed in comparison to deep veins (four of five). Images of symptomatic patients were less consistent with difficulty suppressing muscle and deep venous signal in some cases and edema when present. We then compared T2 values for muscle (T2m, tibialis anterior), arterial blood (femoral and popliteal arteries), and venous blood (femoral, popliteal, and saphenous veins) in controls (n = 8) and symptomatic patients with intermittent claudication (n = 5) or ischemic rest pain (n = 7). Changes in T2 measurements of various tissues accounted for poorer contrast in symptomatic patients. Patients with ischemic rest pain had significantly higher T2m compared with controls (T2m = 39.3 ± 2.1 (1 standard error of the mean [SEM]) versus 30.9 ± .4, P < .01). For all measurements, other than saphenous vein, variances were greater in symptomatic patients. To realize the inherent advantages of FIA for this clinical application, additional work on suppression of signals from muscle, veins, and edema is required. One promising approach involves shifting from projection images to three-dimensional acquisitions for improved tissue suppression. 相似文献
38.
Summary This study describes reduced motor nerve conduction velocity and increased resistance to hypoxia-induced conduction failure in sciatic nerves of rats after four weeks of streptozotocin-induced diabetes (both effects were significant at p <0.05). These changes occurred in the absence of any deficit in the steady-state ouabain-sensitive adenosine triphosphatase (ATPase) activity of sciatic nerve endoneurial homogenates. The addition of 10 nmol/l insulin to endoneurial homogenates from control animals resulted in a 34% increase in ouabain-sensitive ATPase activity and a 19% reduction in ouabain-insensitive ATPase activity (both p <0.01). This stimulation of ouabain-sensitive ATPase activity by insulin did not occur in homogenates from diabetic rats. Treating diabetic rats daily with the aldose reductase inhibitor, imirestat (1 mg/kg) improved nerve conduction velocity (p <0.05) but was without effect upon the resistance to hypoxic conduction blockade or the deficit in insulin-stimulated oubain-sensitive ATPase activity. These data suggest that in streptozotocin-diabetic rats the functional disorders of reduced motor nerve conduction velocity and increased resistance to hypoxic conduction blockade do not share a common aetiology and that impaired nerve conduction is not related to reduced maximal potential oubain-sensitive ATPase activity. 相似文献
39.
目的 :评价平板式全数字心血管造影机在周围血管及非血管介入中的应用价值。方法 :对平板探测器(FPDD)X线成像与影像增强器 电视 (IITV)X线成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标的检测及比较。随机选择上述两机型在周围血管及非血管介入诊疗病例图像资料各 6 0例 ,由三名高年资医师对其图像质量进行综合评价 ,记录评价结果 ,并进行比较。结果 :FPDD成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标均优于IITV成像 ;在人体各部位周围血管及非血管介入诊疗中的图像综合评价结果也优于IITV成像。结论 :平板式全数字化心血管造影机不仅适用于心血管介入 ,同时能满足全身各部位周围血管及非血管介入诊疗的需要。 相似文献
40.
Membrane flow within the myelin sheath in IDPN neuropathy 总被引:1,自引:0,他引:1
A. E. BLAUROCK M. B. GENTER ST CLAIR D. G. GRAHAM 《Neuropathology and applied neurobiology》1991,17(4):309-321
This report describes some aspects of beta,beta'-iminodipropionitrile (IDPN) neuropathy in rats as observed by ultrastructural methods and X-ray diffraction. Light microscopy shows gross swelling of the axons in proximal lumbar spinal roots 8 days after intraperitoneal injection of IDPN. Mean axon cross-sectional area and mean axon perimeter increased to 280% and 160% of their control values, respectively. At the same time, myelin membrane packing was not visibly disturbed. In addition, X-ray diffraction patterns, recorded under physiological conditions, demonstrate that the myelin lipid bilayer thickness and widths of the aqueous spaces between bilayers did not change. Related observations are made on posterior tibial nerve (PNS myelin) and ventral spinal cord (CNS myelin). The various observations together are interpreted in terms of a fluid myelin membrane. It is proposed that the myelin membrane flows during axon swelling even though normal membrane-membrane contacts are maintained within the sheath. Membrane flow and slippage between membranes are explained in terms of a molecular model of the myelin multilayer. 相似文献