全文获取类型
收费全文 | 53278篇 |
免费 | 3453篇 |
国内免费 | 246篇 |
专业分类
耳鼻咽喉 | 670篇 |
儿科学 | 1238篇 |
妇产科学 | 1279篇 |
基础医学 | 7400篇 |
口腔科学 | 1542篇 |
临床医学 | 5843篇 |
内科学 | 11452篇 |
皮肤病学 | 830篇 |
神经病学 | 5319篇 |
特种医学 | 1835篇 |
外科学 | 6708篇 |
综合类 | 385篇 |
一般理论 | 46篇 |
预防医学 | 3839篇 |
眼科学 | 861篇 |
药学 | 3683篇 |
1篇 | |
中国医学 | 64篇 |
肿瘤学 | 3982篇 |
出版年
2023年 | 307篇 |
2022年 | 545篇 |
2021年 | 1185篇 |
2020年 | 770篇 |
2019年 | 1030篇 |
2018年 | 1254篇 |
2017年 | 1110篇 |
2016年 | 1304篇 |
2015年 | 1373篇 |
2014年 | 1818篇 |
2013年 | 2608篇 |
2012年 | 3928篇 |
2011年 | 4113篇 |
2010年 | 2444篇 |
2009年 | 2233篇 |
2008年 | 3416篇 |
2007年 | 3727篇 |
2006年 | 3358篇 |
2005年 | 3397篇 |
2004年 | 3104篇 |
2003年 | 2893篇 |
2002年 | 2663篇 |
2001年 | 516篇 |
2000年 | 450篇 |
1999年 | 553篇 |
1998年 | 591篇 |
1997年 | 501篇 |
1996年 | 424篇 |
1995年 | 373篇 |
1994年 | 322篇 |
1993年 | 341篇 |
1992年 | 285篇 |
1991年 | 296篇 |
1990年 | 254篇 |
1989年 | 282篇 |
1988年 | 262篇 |
1987年 | 219篇 |
1986年 | 224篇 |
1985年 | 248篇 |
1984年 | 216篇 |
1983年 | 195篇 |
1982年 | 202篇 |
1981年 | 173篇 |
1980年 | 149篇 |
1979年 | 125篇 |
1978年 | 142篇 |
1977年 | 143篇 |
1976年 | 107篇 |
1975年 | 113篇 |
1974年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
Andries R. Jonkhoff Peter C. Huijgens Willem O. Schreuder Gerrit J. J. Teule Jan J. Heimans 《Journal of neuro-oncology》1993,17(2):155-158
Summary A patient is described with a testicular Non-Hodgkin's Lymphoma (NHL) presenting with panhypopituitarism caused by a hypophyseal localization. A67Gallium scintigraphy showed avid uptake in the hypophyseal region. Obviously67Gallium could reach the tumor, by the intravenous route, which was the reason to treat the patient with intravenous chemotherapy. A complete remission was induced, which seems to be lasting (+ 25 months). As far as we know this is the first report of panhypopituitarism caused by a hypophyseal NHL in the hypophysis and successfully treated by intravenous chemotherapy. 相似文献
72.
Anionic polymerization of ?-caprolactam was initiated with the potassium salt of ?-caprolactam and accelerated with phenyl isocyanate, toluylene diisocyanate, 4,4′-diphenylmethane diisocyanate, some derivatives of these isocyanates (urethanes, ureas, and allophanates), or combinations of phenyl isocyanate with its derivatives at 150°C. The effect of individual structures on the polymerization kinetics and their contribution to the preparation of block copolymers of ?-caprolactam with hydroxy-terminated prepolymers, in-situ functionalized with diisocyanates, are discussed on the basis of a detailed analysis of time functions of polymer yield and degree of polymerization. 相似文献
73.
Mice homozygous for the lpr mutation have B and T cell defects and develop autoantibodies, suggesting that lpr plays a role in their genesis. The lpr defect has been identified as a mutation in the apoptosis-associated Fas receptor (FasR) gene. To begin to define the role of FasR in B cells, we have surveyed FasR expression on B-lineage cells from early progenitors in the bone marrow through their maturation in the periphery. Contrary to some reports, we found that FasR is expressed on B cells at all stages of their development and is highest on germinal center B cells. FasR is not expressed on lpr/lpr-derived cells. These data are consistent with the idea that lpr/lpr mice have an intrinsic B cell defect that may be manifested in developing as well as peripheral B cells. An unexpected finding is that B-1 (CD5) B cells do not constitutively express FasR: FasR becomes detectable on B-1 B cells only after activation. 相似文献
74.
75.
Krister S. Eriksson Nina Peitsaro Kaj Karlstedt Jan Kaslin Pertti Panula 《The European journal of neuroscience》1998,10(12):3799-3812
The histamine-storing neural system in adult and developing zebrafish (Danio rerio) was studied with immunocytochemical and chromatographical methods. Furthermore, the gene for histidine decarboxylase was partially cloned and its expression mapped with in situ hybridization. The histamine-storing neurons were only seen in the caudal hypothalamus, around the posterior recess of the diencephalic ventricle. Almost all parts of the brain, except the cerebellum, contained at least some histamine-immunoreactive fibres. The ascending projections had the rostral part of the dorsal telencephalon as a major target. Descending projections terminated in the torus semicircularis, central grey and inferior olive. A prominent innervation of the optic tectum, which has not been reported in other fish, was seen. The in situ hybridization gave a strong signal in cells with the same anatomical position as the histamine-immunoreactive neurons. The first histamine-immunoreactive neurons appeared in the ventral hypothalamus at about 85 h post-fertilization, and at 90 h, immunoreactive fibres terminated in the dorsal telencephalon. The embryonic histamine production described in mammals was lacking in this species. Both immunocytochemical and chromatographical studies indicated that histamine is absent in all other parts of the zebrafish body, and no specific hybridization was seen in any other part of the fish than the hypothalamus. The zebrafish could therefore be a very useful model for pharmacological in vivo studies of the histaminergic system of the brain, since the powerful peripheral actions of histamine should be lacking in this species. 相似文献
76.
J. G. Boonstra Johan W. van der Pijl Yves F. C. Smets Herman H. P. J. Lemkes Jan Ringers Leendert A. van Es F. J. van der Woude Jan A. Bruijn 《Transplant international》1997,10(6):451-456
To examine the incidence of interstitial and vascular
rejection in pancreas allografts and its impact on graft survival, we studied 36 percutaneous pancreas biopsies and 10 pancreas
transplantectomy specimens from 32 patients who had undergone simultaneous pancreas-kidney transplantation. Interstitial rejection
(IR) was predominantly found in the biopsies, while vascular rejection (VR) was most prominent in the transplantectomies.
Pancreas graft survival was significantly decreased for pancreas grafts that had suffered from vascular rejection when compared
to those with only interstitial rejection. Potential rejection markers, i. e., serum amylase, glucose, creatinine, and urinary
amylase, did not correlate with histological signs of rejection, although increased levels of serum amylase were, in all but
one case, associated with rejection.We conclude that a percutaneous pancreas biopsy remains the most reliable method to determine
pancreas rejection, and that by distinguishing between IR andVR, a pancreas biopsy may provide important diagnostic as well
as prognostic information.
Received: 6 March 1997 Received after revision: 5 June 1997 Accepted: 30 June 1997 相似文献
77.
This study explored the inflammatory mechanism of toxicity of hemoglobin solutions (Hb-S). Human monocytes and mouse activated peritoneal macrophages were incubated with seven different solutions. The first four consisted of non-cross-linked bovine Hb. Of these, Hb-SI was incompletely purified of stromal phospholipids, Hb-SII was contaminated with environmental bacterial endotoxins, Hb-SIII was pure hemoglobin, and Hb-SIV was pure Hb with the addition of superoxide dismutase (SOD), catalase (CAT), and mannitol (M). The other three solutions were made of pure bovine Hb cross-linked with different agents: Hb-SV, reacted with glutaraldehyde; Hb-SVI reacted with bis-3,5-dibromosalicyl fumarate (DBSF); and Hb-SVII reacted with a ring-opened dialdehyde derivative of 5'(pyro)-phosphate of adenosine (ATP) (o-ATP). The reaction of monocytes and macrophages was studied in terms of (a) O2-derived radicals, as determined by the measurement of H2O2 and lipid peroxides; (b) complement factor C3a desArg; (c) 6-keto-prostaglandin F1 alpha (stable metabolite of prostacyclin); and (d) TxB2 (stable metabolite of thromboxane) released into the culture supernatants. The most significant reactions were obtained with the solutions contaminated with stromal phospholipids or bacterial endotoxins. Pure Hb was less reactive. Further reduction in proinflammatory activity was achieved by the addition of oxygen radical-scavengers (SOD, CAT, and M), or by the cross-linking of Hb with DBSF or o-ATP. 相似文献
78.
Jan E. Zejda Thomas S. Hurst Ernest M. Barber Charles Rhodes James A. Dosman 《American journal of industrial medicine》1993,23(5):743-750
A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, betweengroup comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection. © 1993 Wiley-Liss, Inc. 相似文献
79.
80.
N-acetylaspartate is an axon-specific marker of mature white matter in vivo: a biochemical and immunohistochemical study on the rat optic nerve. 总被引:5,自引:0,他引:5
Carl Bjartmar Jan Battistuta Nobuo Terada Erica Dupree Bruce D Trapp 《Annals of neurology》2002,51(1):51-58
Axonal pathology is a major cause of neurological disability in multiple sclerosis. Axonal transection begins at disease onset but remains clinically silent because of compensatory brain mechanisms. Noninvasive surrogate markers for axonal injury are therefore essential to monitor cumulative disease burden in vivo. The neuronal compound N-acetylaspartate, as measured by magnetic resonance spectroscopy, is currently the best and most specific noninvasive marker of axonal pathology in multiple sclerosis. The possibility has been raised, however, that N-acetylaspartate is expressed also by oligodendroglial lineage cells. In order to investigate N-acetylaspartate specificity for white matter axons, transected rat optic nerves were analyzed by high-performance liquid chromatography and immunohistochemistry. In transected adult nerves, N-acetylaspartate and N-acetyl aspartylglutamate decreased in concordance with axonal degeneration and were undetectable 24 days posttransection. Nonproliferating oligodendrocyte progenitor cells, oligodendrocytes, and myelin were abundant in these axon-free nerves. At 24 days posttransection, N-acetylaspartate was increased (42%; p = 0.02) in nontransected contralateral nerves. After transection at postnatal day 4, total N-acetylaspartate decreased by 80% (P14; p = 0.002) and 94% (P20; p = 0.003). In these developing axon-free nerves, 25 to 33% of oligodendrocyte progenitor cells were proliferating. These data validate magnetic resonance spectroscopy measurements of N-acetylaspartate as an axon-specific monitor of central nervous system white matter in vivo. In addition, the results indicate that neuronal adaptation can increase N-acetylaspartate levels, and that 5 to 20% of the N-acetylaspartate in developing white matter is synthesized by proliferating oligodendrocyte progenitor cells. 相似文献